Modelling of FACTS Power System controller using IEC 61850
Johan Malmström
johan.malmstrom@se.abb.com
DVA331 - Computer Science, Basic Level
Report
Advisor: Mats Björkman
Examiner: Mikael Ekström
Advisor at ABB FACTS: Carl Heyman
January 18, 2015
Abstract
The International Standard ”IEC 61850: Communication networks and systems for power utility automation”,
describes different domains with-in power systems. The power system application Flexible Alternating Current Transmission System, FACTS, has not yet been described and can therefore not be modelled correct.
This report presents a suggestion on how to model FACTS Controllers in IEC 61850. Based on use cases
for communication interfaces, defining operation modes and different control and protection functionality and
analysing power system equipment used in FACTS Controllers the report extends existing logical nodes and
introduces new logical nodes and common data classes. From a modelling perspective a use case for a Static
VAR Compensator, SVC, have been used. The work includes a UML model of the suggested additions to the
standard.
The report also contains a comparison with other domains of power systems.
Contents
1
Thesis Description
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Outline of this report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Introduction to IEC 61850
2.1 History of communication in substations . . . . . . . . . . . . . . . . . .
2.2 IEC 61850; the standard for Communication in power system substation
2.3 Data modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3.1 UML model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 Communication and data models in IEC 61850 . . . . . . . . . . . . . . .
2.4.1 Station Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4.2 Bay Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4.3 Process Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 Brief introduction to System Configuration description Language, SCL .
2.5.1 Engineering process . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5.2 The SCL object model . . . . . . . . . . . . . . . . . . . . . . . . .
2.5.3 SCL Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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3
3
3
5
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10
10
Introduction to FACTS controllers
3.1 History and introduction to controlling power transmission
3.2 Shunt technologies of today . . . . . . . . . . . . . . . . . . .
3.2.1 Thyristor based FACTS Controller . . . . . . . . . . .
3.2.2 Converter based FACTS Controller . . . . . . . . . . .
3.3 Modern series technologies . . . . . . . . . . . . . . . . . . .
3.3.1 Fixed SC . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.2 Thyristor Controlled Series Compensator . . . . . . .
3.4 Operating modes of a FACTS Controller . . . . . . . . . . . .
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12
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4
Use case: SVC
4.1 Communication interfaces in a SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Analysis of use case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
16
5
Operating and control modes of FACTS Controllers
5.1 Operating modes of FACTS Controllers . . . . . . . . . . . . . . . . . . . . .
5.1.1 Definition of a state machine for operating modes . . . . . . . . . . .
5.1.2 Control locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1.3 Degraded mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1.4 Relationship between different control modes and open loop control
5.2 Voltage control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3 Reactive Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.1 Slow susceptance or VAr regulator . . . . . . . . . . . . . . . . . . . .
5.3.2 External banks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4 Power Oscillation Damping mode . . . . . . . . . . . . . . . . . . . . . . . .
5.5 Parallel controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6 Protective control modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.1 Protection of FACTS controllers with power electronics . . . . . . . .
5.6.2 Protection of Series compensation . . . . . . . . . . . . . . . . . . . .
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ii
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1
1
2
2
6
7
8
9
Data modelling
6.1 Substation level of a FACTS controller . . . . . . . . .
6.2 Modelling logic and system state . . . . . . . . . . . .
6.2.1 Controlling operation modes of FACTS device
6.2.2 Voltage Control . . . . . . . . . . . . . . . . . .
6.2.3 Reactive Power Control . . . . . . . . . . . . .
6.2.4 Modelling of POD Control . . . . . . . . . . .
6.2.5 Modelling of Parallel Controllers . . . . . . . .
6.2.6 Reinsertion-logic . . . . . . . . . . . . . . . . .
6.3 Modelling of Protection control modes . . . . . . . . .
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28
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34
34
Analysing and modelling of Single Line Diagram objects
7.1 Mapping of traditional SCADA signal list items to IEC 61850, modeling Bottom-up
7.2 Modelling primary equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.2.1 Indication and Control of Breakers and Switches . . . . . . . . . . . . . . . .
7.2.2 Metering and Measured values . . . . . . . . . . . . . . . . . . . . . . . . . .
7.2.3 Power Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3 Branches of shunt connected FACTS Controller . . . . . . . . . . . . . . . . . . . . .
7.3.1 Supervision of Power Electronics . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.2 Reactive Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.3 Thyristor controlled Reactive Component branches: TCR, TSR and TSC . .
7.3.4 Reactive component branch with a Voltage Source Converter: VSC . . . . .
7.3.5 Logical nodes for Reactive Components Branches . . . . . . . . . . . . . . .
7.4 Harmonic Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5 Mechanically switched reactive components . . . . . . . . . . . . . . . . . . . . . .
7.6 Fast protective device and by-pass gap . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.1 Use case for Spark gap or Fast Closing Device . . . . . . . . . . . . . . . . .
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37
37
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43
Modelling of Distributed Energy Resources (DER), Wind and Hydro power plants
8.1 New domains with-in IEC 61850 . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1.1 DER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1.2 Hydro power plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1.3 Wind power plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1.4 Other domains where modelling is needed . . . . . . . . . . . . . . . . .
8.2 Comparison and influences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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47
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48
Conclusions
9.1 Future work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
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A Svenska Kraftnäts Kraftsystemkarta
54
B Single Line Digram Series Capacitor, one segment
56
C Single Line Digram SVC
57
D Introduction to control system for FACTS controllers
59
D.1 Control system for communication, system interaction, protection and control of power electronics 59
E Published parts of IEC 61850
61
F Basic Types defined in IEC 61850-7-2
62
G Proposed instantiation
G.1 Nomenclature and structure set by the IEC 61850 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G.2 Single Line Diagram items used in use case and example implementation . . . . . . . . . . . . .
G.3 Overview of IEDs, Logical Devices and Logical Nodes . . . . . . . . . . . . . . . . . . . . . . . . .
65
65
66
66
H Suggestions for standard updates
70
iii
List of Figures
1.1
2.1
2.2
2.3
2.4
3.1
3.2
3.3
Single line diagram (SLD) of a SVC containing a thyristor controlled reactor, a thyristor switched
capacitor and a double tuned filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data modelling in IEC 61850. Figure is part of IEC standard. . . . . . . . . . . . . . . . . . . . . .
The UML model of the IEC 61850 domain, represents IEC 68150-7. Figure is part of UML-model
of IEC 61850 standard [Kos14]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Communication interfaces of IEC 61850. Figure is part of IEC standard. . . . . . . . . . . . . . . .
The different SCL-files and their usage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
5
6
7
9
13
13
3.4
SLD for the Extremoz SVC deliverd by ABB to Mexico. . . . . . . . . . . . . . . . . . . . . . . . .
A simplified single line diagram of a STATCOM . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Single line diagram of a Series Capacitor, showing Disconnector on the line, and By-pass breaker
in parallel with the capacitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conceptual single line diagram of a Thyristor Controlled Series Compensator. . . . . . . . . . . .
4.1
4.2
4.3
Single line diagram of use case SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Communication interfaces for use case. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use case for Operators interaction and relationship between the SVCs functions. . . . . . . . . .
15
16
17
5.1
5.5
The state machine describe the operating modes of a FACTS Controllers. Steady states are
marked with thicker frames and transient states with thiner frames. . . . . . . . . . . . . . . . . .
State machine describing the relationship between control modes of a FACTS controller. . . . . .
Typical block diagram of the Voltage Control for an SVC. Example from [MV02] . . . . . . . . .
A VI-diagram showing the operating characteristic of a shunt connected FACTS device with slow
susceptance regulator. Figure is inspired by [MV02] . . . . . . . . . . . . . . . . . . . . . . . . . .
Outline of SVC voltage control system with additional reference signal for POD . . . . . . . . . .
6.1
6.2
6.3
6.4
6.5
6.6
Mapping between real world FACTS and virtualization in IEC 61850.
UML representation of new Cxxx nodes. . . . . . . . . . . . . . . . . .
UML representation of new CDC . . . . . . . . . . . . . . . . . . . . .
UML representation of new Axxx nodes. . . . . . . . . . . . . . . . . .
UML representation of new RRIN node. . . . . . . . . . . . . . . . . .
UML representation of new Pxxx nodes. . . . . . . . . . . . . . . . . .
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29
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36
7.1
7.2
7.3
7.4
Example Holly STATCOM, Texas 80 Mvar inductive to 110 Mvar capacitive.
New LN Zxxx to represent SLD objects described in this report. . . . . . . .
Use case for Spark gap or Fast Protective Device . . . . . . . . . . . . . . . .
LN: XFPD to represent Fast Protective Device or Spark Gap . . . . . . . . . .
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37
44
45
46
8.1
8.2
Simplified network of a hydropower plant. Figure is part of IEC/TR 61850-7-510. . . . . . . . . .
Conceptual organisation of DER logical devices and logical nodes. Figure is part of IEC 618507-510. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Model of FACTS Controller and virtualisation in IEC 61850 as described in this report. . . . . . .
48
A.1 The nordic transmission line grid system. The right to the picture belongs to SVK. . . . . . . . .
55
B.1 Single Line Diagram of a one segment Series Capacitor. . . . . . . . . . . . . . . . . . . . . . . . .
56
C.1 Single Line Diagram of a SVC with 2 TCR and 2 TSC branches. . . . . . . . . . . . . . . . . . . . .
C.2 Example Single Line Diagram of a Thyristor Switched Capacitor. . . . . . . . . . . . . . . . . . .
C.3 Example Single Line Diagram of a Thyristor Controlled Reactor . . . . . . . . . . . . . . . . . . .
57
58
58
5.2
5.3
5.4
8.3
iv
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14
14
18
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21
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24
48
49
D.1 Communication structure of a shunt connected FACTS device. . . . . . . . . . . . . . . . . . . . .
60
F.1
Interface diagram of types defined in IEC 61850-7-2. Figure is part of IEC standard. . . . . . . . .
64
G.1 Overview of IEDs of the use case used in this report. . . . . . . . . . . . . . . . . . . . . . . . . . .
G.2 Overview of Logical Devices of one IED in the use case. . . . . . . . . . . . . . . . . . . . . . . . .
G.3 Overview Substation view of FACTS Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
67
68
69
H.1 Overview of additions to IEC 61850 presented in this report. . . . . . . . . . . . . . . . . . . . . .
H.2 Overview of LN additions to IEC 61850 presented in this report. . . . . . . . . . . . . . . . . . . .
H.3 UML representation of new CDCs presented in this report. Same as Figure 6.3 . . . . . . . . . . .
71
71
72
v
List of Tables
2.1
Communications interfaces defined in IEC 61850 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
3.1
Thyristor controlled reactive components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
Operating mode and Operating location process data . . . . . . . . . . . . . .
Voltage Control process data . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reactive Power Control process data . . . . . . . . . . . . . . . . . . . . . . . .
Process data for external banks . . . . . . . . . . . . . . . . . . . . . . . . . . .
Process data for Power Oscillation Damping. . . . . . . . . . . . . . . . . . . .
Process data for Parallel controllers. . . . . . . . . . . . . . . . . . . . . . . . .
Protection related to voltage control. . . . . . . . . . . . . . . . . . . . . . . . .
Protection of thyristor controlled reactive components . . . . . . . . . . . . . .
Overview of typical series capacitor bank protections. Based on IEC 60143-2.
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19
21
23
23
24
25
25
26
27
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
Interpretation of logical node description tables . . . . . . . . . . . . . . . . .
LN: CPEM — Control of Power Electrical Machine . . . . . . . . . . . . . . . .
LN: AVCO — Voltage Control . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LN: ARPC — Reactive Power Control . . . . . . . . . . . . . . . . . . . . . . .
LN: APOD — Power Oscillation Damping Control . . . . . . . . . . . . . . . .
LN: CJCL — Control of parallel FACTS Controllers . . . . . . . . . . . . . . .
LN: PRCC — Current Protection of Thyristor Controlled Reactive Component
LN: PTRV — Voltage protection of Thyristor controlled Reactive Component
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28
29
32
33
35
35
35
35
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
CDC: VST — Valve Status Common Data Class . . . . .
Process data for Reactive Component Branch . . . . . .
Thyristor controlled Reactive Component process data
Voltage Source Converter process data . . . . . . . . . .
Abstract LN - ReactiveComponentBranchLN . . . . . .
LN: ZTCR - Thyristor controlled reactive component .
LN: ZHAF — Harmonic Filter . . . . . . . . . . . . . . .
LN: XFPD — Fast Protective Device . . . . . . . . . . .
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40
40
41
42
42
42
43
45
E.1 A list of published parts of the standard and the current edition w publication year . . . . . . . .
61
F.1
The Basic Types as defined in IEC 61850 Part 7-2, Table 2[WG110a] . . . . . . . . . . . . . . . . .
63
G.1 SLD items modelled in example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
66
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Chapter 1
Thesis Description
The work presented in this report will be used by ABB in the work of defining the extension of the International
Standard IEC 61850 with modelling of FACTS, HVDC and Power conversions1 . Where needed, property of
ABB and IEC has been obscured or removed to protect from disclosure of intellectual property of these entities.
Figure 1.1: Single line diagram (SLD) of a SVC containing a thyristor controlled reactor, a thyristor switched
capacitor and a double tuned filter
1.1
Background
The International Standard IEC 61850 is a standard for the design of electrical substation automation. Substations are the building blocks of the electric grid and they connects the transmission and distribution networks.
Substation automation is done with Intelligent Electronic Devices (IEDs), computer based systems used for
control, protection, monitoring and operation of the substations. A Substation Automation System (SAS) is
the combined system of IEDs. The SAS is also the interface for more advanced functions like power system
management like energy management and planning. The abstract data models defined in IEC 61850 can be
mapped to a number of protocols. Current mappings in the standard are to MMS (Manufacturing Message
Specification), GOOSE, SMV (Sampled Measured Values), and soon to Web Services. These protocols can
run over TCP/IP networks or substation LANs using high speed switched Ethernet to obtain the necessary
response times below four milliseconds for protective relaying.
A flexible alternating current transmission system (FACTS) is a system composed of static equipment used
for the AC transmission of electrical energy. It is meant to enhance controllability and increase power transfer
1 Acronyms
will be explained later and is also listed in a glossary at the end of the report.
1
capability of the network. It is generally a power electronics-based system. FACTS is defined by the IEEE2 as ”a
power electronic based system and other static equipment that provide control of one or more AC transmission
system parameters to enhance controllability and increase power transfer capability”. Remote interaction with
FACTS controllers have traditionally used SCADA-protocols or vendor specific solutions for communications.
When the standard IEC 61850 for substation and inter-substation communication where introduced it
lacked abstract data models for a lot of domains of substations like Wind and Hydro power plants. Among
these domains a standard abstract data model describing FACTS controllers is missing.
1.2
Tasks
• Describe use cases for communication for the different part of a FACTS controller, and suggest solutions
where IEC 61850 can be used. Example of affected parts of IEC 61850 is part 5, 8-1, 9-2 and 90-1.
This is described in Section 4.1 where the different communication interfaces of a FACTS Controller is
showed and mapped on to the communication model of IEC 61850.
• Design and verify a data model. Propose Logical Nodes for describing the FACTS controller process. This
might include extension of existing logical nodes, definition of new logical nodes, common data classes,
etc. The additions shall be implemented in UML and conform to the standard. Example of affected parts
of IEC 61850 is part 6, 7, 8 and 9.
The data modelling begins in Chapter 6.
• Comparison with other solution or data model within IEC 61850. Estimated time for this is 1 week.
The comparison has resulted in influences on the modelling, but specific points are also discussed in
Chapter 8.
• Presenting the result in a report and presentation. The paper should include introduction to Substation
communication, IEC 61850 and FACTS Controllers as well as related work and future work.
1.3
Outline of this report
This report begins with a gentle introduction of the International Standard IEC 61850 and the power system
application FACTS. Chapter 4 establish an example SVC which is used as basis through out the report for
modelling of a specific case where the general case of FACTS would be to abstract.
The Chapters 5, 6 and 7 then contain the discussion and proposals on how to model a FACTS Power
System Controller with IEC 61850. Additionally Chapter 8 compares with other domains of power system
applications. Before the report ends with various appendices a glossary (on page 53) and the bibliography (on
page 52) can be found. The appendices include more background information and further details, proposal of
input to changes and additions to the IEC 61850-standard and a proposed structure of implementation.
2 Institute
of Electrical and Electronics Engineers, an international association for engineering and science.
2
Chapter 2
Introduction to IEC 61850
The international standard IEC 61850 is defined in a set of publications by IEC, International Electrotechnical
Commission. The work with the standard started in 1995, and the first publications of the main parts of the
standard were between 2002 to 2005. A list of current parts is supplied in Appendix E. The work with developing IEC 61850 is done by Working Group 10 (WG10) within Technical Committee 57 (TC57) of IEC1 . The official
name of the standard was changed when Edition 2 started to be developed , to ”Communication networks and
systems for power utility automation” from ”Communication networks and systems in substations” to reflect
the extended scope of the standard.
This chapter gives a brief historical overview of substation communication and introduces the standard
and its parts.
2.1
History of communication in substations
The electric utility power systems have used SCADA, Supervisory Control And Data Acquisition, communications since the early electromechanical single-function protection and control relays where used[KWU+ 06,
Ger12]. The driving forces behind developing remote monitoring and remote control of key parameters where
reliability(the customers of the power utilities demanded reliable electrical power) and that cost of labour
at the manned substations where increasing. The early SCADA communication was very limited, generally
monitoring of bus voltage and few aggregated alarms and control of circuit breakers. The communication was
centralised and vendor specific[Nor08a, KWU+ 06].
The term IED, Intelligent Electronic Device, was introduced with microprocessor-based multifunction units.
These IEDs could singly replace whole groups of the old electromechanical relays. The IEDs could perform
all the functionality needed in a substation, e.g. protection, local and remote monitoring and control. With
this development it arouse a need for efficient communication between IEDs. The first communications between IEDs still used vendor specific and proprietary communications protocols. The result of this was very
cumbersome and expensive protocol converters.
In North America the communication standard Utility Communication Architecture (UCA) [Nor08b] was
used by power utilities. It defined protocols, data models and abstract service definitions2 . European power
utilities used the IEC standard IEC 60870-53 [TC590], which described a communication profile for sending
tele-control messages between two systems, based on a directly connected data line.
2.2
IEC 61850; the standard for Communication in power system substation
The objective with IEC 61850 was to develop one standard for substation communication, the drivers where
to improve device data integration into the information and automation technology and reducing the costs
for the whole life cycle of a substation. One can argue that the device cost for an IEC 61850 IED is higher but
counting the cost for engineering, commissioning, operation, monitoring, diagnostics, asset management, and
maintenance one can see that the total cost is lower[RM, Bla07] .
IEC 61850 started out to bring interoperability, i.e. communication exchange of information, between devices within a substation. By defining a standard communication interface the standard should make it pos1 The
scope of TC57 is Power systems management and associated information exchange.
on physical, data link, and network standard and includes both TCP/IP and OSI communication architecture.
3 IEC 60870 standards define systems used for tele-control, SCADA. IEC 60870-5 provides a communication profile for sending basic
tele-control messages between two systems, which uses permanent directly connected data circuits between the systems.
2 Based
3
sible for a substation to be engineered with devices from different vendors. IEC 61850 describes the use of a
server-client interface, where the the servers (generally IEDs controlling equipment) provides information and
receives commands to the clients (generally station computers or HMI). One difference between IEC 61850 and
earlier SCADA protocols is that it has an object-oriented approach so that a device can describe its attributes
when asked4 .
Included in the standard is description of
Data modelling. The standard describes primary equipment (i.g. high voltage equipment like breakers and
transducers) and the secondary equipment (protection and control IEDs) functionality associated with
the primary equipment. The modelling is done using logical nodes (part 7-4[WG110c]) grouped together
in logical devices. The logical nodes consists of data attributes with types defined in Common Data
Classes (CDC) described in part 7-3[WG110b]. A logical device has as least one logical node (LLN0)
and generally a logical node representing the physical device (LPHD). The logical nodes are associated
in namespaces. The communication interface is described in part 7-2[WG110a] as Abstract Communication Service Interface (ACSI). The communication is mapped on MMS and Ethernet specified in part
8-1[WG111d] as Specified Communication Service mapping (SCSM). Data modelling is further discussed
in Section 2.2 and is the main objective of this report.
Fast event handling. Generic Substation Events (GSE) is a peer-to-peer communication model described in
IEC 61850 for fast event communication. GSE is subdivided in to Generic Object Oriented Substation
Event (GOOSE) and Generic Substation State Events (GSSE). GOOSE data is directly embedded into
Ethernet data packets. The data is grouped in to data set (status, value) and transmitted within a time
period 4 ms on a Ethernet VLAN. The data packets are tagged using IEEE 802.Q priority tags. The
combination of VLAN and priority tags gives the possibility of real-time data over a Ethernet network.
GSSE is an extension of an older event communication standard5 and uses a status list (string of bits)
instead of data sets that GOOSE uses.
Reporting Schemes that describes how data is sent from server to client and conditions for sending the data.
Part 7-2 defines report-control-block as an entity that
”shall control the procedures that are required for reporting values of data objects from one
or more logical node to one client.”
Setting management. The standard defines how an instance of data object class can switch between sets of
values. The model for this is called setting group control blocks (SGCB) and is defined in Part 7-2
[WG110c] of the standard.
Sampled value communication. The sampled value control blocks (SVCB) is also defined in part 7-2 of the
standard. The sampled measured value communication is a method for transmitting measurements from
transducers like CTs, VTs and digital I/O. Several transducers can be connected to a merging units that
transmits the analog values using Multicast service (MSVC) over Ethernet or Unicast service (USCV)
over serial links (point-to-point). The concept of merging units enables sharing of I/O signals with
several IEDs. Sample value communication is described in [WG111c].
Commands. The standard defines two type of commands direct-control and select-before-operate. The latter can
be seen as selecting action and then submitting (or cancelling), this type of control is common in control
systems where actions needs confirmations.
System and project management. Part 4[WG111a] of the standard describes the engineering and processes of
system and project management of a Utility Automation System. For instance Part 4 defines different
classification, categorisation and types of parameters, engineering and system tools requirement and
documentation requirements.
Configuration language for data definition and storage. Part 6 [WG109a] of the standard describes SCL, the
Substation Configuration Language which purpose is to describe the exchange of data between a system
configuration tool and IED configuration tool. The IED tool is usually vendor specific but the system
configuration tool is generic. To provide this interoperability SCL is used to provide functional specification input to SAS engineering, describe IED capability description and the SA system description. SCL
is further introduced in Section 2.5.
4 Excluding
5 The
UCA which also has an object-oriented architecture.
event transfer mechanism in UCA2.0
4
General requirements of equipment used for Utility Automation Systems are defined in Part 3 [WG113b] of
the standard. Part 3 includes requirements for
”mainly regarding construction, design and environmental conditions for utility communication and automation IEDs and systems in power plant and substation environments. These
general requirements are in line with requirements for IEDs used in similar environments, for
example measuring relays and protection equipment.”
Verification of conformance to the standard is described in Part 10 [WG112a] of the standard.
Figure 2.1: Data modelling in IEC 61850. Figure is part of IEC standard.
2.3
Data modelling
Modelling in IEC 61850 is introduced in Part 1 [WG113a] and further explained in Part 5[WG113c] and 71[WG111b] of the standard. Figure 2.1, published in Part 1, shows the different layers discussed when modelling. The breakdown starts from the physical device, often an IED, and breaking it down to Logical Devices. A
logical device represents a group of logical nodes and defines the communication access points of an IED. The
standard does not restrict the way on how to set up a logical device, but it can only be on one physical device.
In Figure 2.1 the logical node LDx have instances of two logical nodes XCBR1(instance of logical node XCBR6 )
and MMXU1(instance of logical node MMXU7 ). Logical devices enables modelling of multi-function IED’s.
A logical device is a rather simple construct with constrains that may complicate the modelling of complex
hierarchies, the standard exemplifies with distance protection and this report will provide another example
where the basic functionality is not sufficient. In the Edition 2 of Part 6 [WG109a] and Part 7 of the standard
introduce the concept of an hierarchy of Logical Devices. This concept makes is possible to manage nested
functions and sub-functions.
A Logical Node represent the lowest level of a virtualised function of physical equipment. The standard define a logical node as[WG113c] ”object where standardised data for communication are grouped in according
to their relationship to application functions” with the note ”The granularity of data or to how many logical
nodes (LN) the data are distributed depends on the granularity of functions. The granularity stops at the smallest function parts which may be implemented as single- stand-alone functions acting also as atomic building
blocks for complex functions. The logical nodes may be seen also as containers containing the data provided
by a dedicated function for exchange (communication). The name of the logical node is than the label attached
to this container telling to what function the data belong. Logical nodes related to primary equipment are not
the primary equipment itself but a data image in the secondary system needed for performing the applications
functions of the power utility automation system.”
A Logical Node is built up with properties called Data Objects. The type of a data object is a Common Data
class. Common data classes are defined in Part 7-3[WG110b], and has been defined for:
1. Status Information
2. Measured information
3. Controllable status information
4. Controllable Analogue set point information
6 XCBR
is ”used for modelling switches with short circuit breaking capability”[WG110c].
”shall be used for calculation of currents, voltages, powers and impedances in a three-phase system”[WG110c].
7 MMXU
5
5. Status settings
6. Analogue settings
The Data Attributes holds the actual data and are derived from the basic types, defined by the standard in
Part 7-2. The basic types is quoted in Table F.1 and the relationship between the defined types in Part 7-2 is
visualised in an UML interface diagram in figure F.1.
2.3.1
UML model
Figure 2.2: The UML model of the IEC 61850 domain, represents IEC 68150-7. Figure is part of UML-model of
IEC 61850 standard [Kos14].
UML was chosen in 2010 to describe IEC 61850 content. The expected benefits of for the standard is to
increase the consistency and facilitate the extension of application domains for IEC 61850. To initiate this work
a specific task force within TC57 WG10 was formed. The work with the UML model is ongoing, and the model
is used to describe the amendment to the standard referred to a as Edition 2.1 of Part 7.
The UML model chosen for this work was the latest available in December 2014[Kos14].
2.4
Communication and data models in IEC 61850
This section describes the different levels in an substation and the communication interfaces between them. In
Section 6.1 the relation between the a substation and FACTS Controllers are discussed.
6
Figure 2.3: Communication interfaces of IEC 61850. Figure is part of IEC standard.
The Figure 2.3 is used in the standard to describe all the different communication interfaces to IEC 61850.
The figure can be interpreted either logical or physical. The meaning of the interfaces enumerated in the figure
are shown in Table 2.1. In the table one can also find where the communication is defined (if relevant). The
following sections will introduce the different logical and physical properties of the layers and the modelling
suggested by the standard.
2.4.1
Station Level
The physical interpretation of Station Level is the for example station Human machine interface (HMI) for the
operator’s workplace and interfaces for remote communications.
The logical interpretation of station level functions are described in Part 5 of the standard as
”There are two classes of station level functions:
Process related station level functions are functions using the data of more than one bay or of the
complete substation and acting on the primary equipment of more than one bay or of the complete
substation. These functions communicate mainly via the logical interface 8.
Interface related station level functions are functions representing the interface of the SAS to the
local station operator (Human machine interface (HMI)), to a remote control centre (Tele-control interface (TCI)) or to the remote engineering place for monitoring and maintenance (Tele-monitoring
interface (TMI)). These functions communicate via the logical interfaces 1 and 6 with the bay and
via the logical interfaces 7 and 10 to the outside world.”
2.4.2
Bay Level
At Bay Level the physical interpretation consists of devices for control, protection or monitoring units per bay.
At bay level function can be local, where data is acquired by sensors, like current transformers (CT) and
voltage transformers (VT), and actions are performed by actuators (switches) in the same bay. If functions uses
sensors and actuators in more than one bay, they are referred to as distributed. The standard describes the
logical interpretation in Part 5 as:
”Bay level functions (see bay definition above) are functions using mainly the data of one bay and
acting mainly on the primary equipment of one bay. These functions communicate via the logical
interface 3 within the bay level and via the logical interfaces 4 and 5 to the process level, i.e. with
any kind of remote I/Os or intelligent sensors and actuators. Interfaces 4 and 5 may be hardwired
also but hardwired interfaces are outside the scope of IEC 61850 series.”
2.4.3
Process Level
Process level physical devices are typically remote I/Os, intelligent sensors and actuators. The process level
functions in a substation needs an interface for binary and analogue I/O, to process orders from the function7
Table 2.1: Communications interfaces defined in IEC 61850
Index
1
2
3
4
5
6
7
8
9
11
12
Communication
Defined in Part
protection-data exchange between bay and station level
protection-data exchange between bay level and remote
protection (e.g. line protection)
data exchange within bay level
analogue data exchange between process and bay level
(samples from current transformers and VT)
control data exchange between process and bay level
control data exchange between bay and station level
data exchange between substation (level) and a remote
engineer’s workplace
direct data exchange between the bays especially for fast
functions like interlocking
data exchange within station level
control-data exchange between the substation and remote
control centre(s)
control-data exchange between substations. This interface
refers mainly to binary data e.g. for interlocking functions
or other inter-substation automatics
9-2
90-2, Not published (December 2014)
90-1
ality, generally implemented in bay-level IEDs. The logical interpretation is described in the standard:
”Process level functions are all functions interfacing to the process. These functions communicate
via the logical interfaces 4 and 5 to the bay level.”
2.5
Brief introduction to System Configuration description Language, SCL
The System Configuration Language (SCL) is defined in Part 6 of the Standard [WG109a]. SCL is the configuration description language used for describe a SAS and its IEDs. The language is based on XML. The purpose
of SCL is described by the standard as
”It is used to describe IED configurations and communication systems according to IEC 61850-5
and IEC 61850-7-x. It allows the formal description of the relations between the utility automation
system and the process (substation, switch yard). At the application level, the switch yard topology
itself and the relation of the switch yard structure to the SAS functions (logical nodes) configured
on the IEDs can be described.”
The languages is described both for a engineering process and for an configuration process.
2.5.1
Engineering process
The engineering process is defined in SCL in how to allow the exchange of information as configuration data
between configuration tools. The exchange between the different tools is based on different file-type. The
types of SCL-files and their role are listed below and also mapped in Figure 2.4.
1. IED Capability Description, ICD-file, is used for describe the capability (Logical Nodes) of an IED.
2. System Specification Description, SSD-file, describes the single line and functional requirements of Logical Nodes.
3. System Configuration Description, SCD-file, is the definition of a specific SAS and includes communication to the LN allocation (on IED-level)
4. Substation Configuration Description, CID-file, is a part of the SCD-file concerning a specific IED. It is
used for IEC 61850-configuration of the IED.
5. Instantiated IED Description, IID-file, provides a subset of the specific IED configuration in relation to
the configured data model
6. System Exchange Description, SED-file, to be used by the System Configuration Tool for configuration
of communication between the systems.
8
Figure 2.4: The different SCL-files and their usage.
9
2.5.2
The SCL object model
The SCL language can be used to describe the primary/power system structure, the communication system,
application level communication, each IED, each instance of logical nodes and relationships between the logical nodes and IEDs on one side and the switch yard parts on the other side. Additionally SCL allows user
specification/extensions of logical nodes by adding data objects.
To accomplish this an SCL-file has three main parts and a number of additional parts. The most common
are:
Header -part serves to identify a SCL configuration file and its version.
Substation -part describes the switch yard equipment, including connection on single line diagram and the
designation of equipment and functions
Product or IED-part includes all IEDs and logical node implementations.
Communication -part includes all communication objects as subnetworks and access points. It also includes
the communication paths between IEDs to define client and servers.
DataTypeTemplates -part determines together with Part 7-3 and Part 7-4 of the standard the possible values
for names of logical nodes prefixes, classes and instances.
The Substation- and IED-part may appear more than once.
2.5.3
SCL Specification
SCL is based on XML and to keep the syntax compact and extensible, SCL uses the type feature of XML. This
enables the inheritance structure for elements. Almost all elements in SCL derives from tBaseElement base
type. The t are part of the naming conventions used:
• schema type names start with the small letter t, as in tSubstation
• attribute group definitions starts with acronym ag, as in agAuthorization
• attribute names start with a lower case letter, as in name
• element names start with a capital letter, as in Substation
The SCL file starts with the header or prolog part, then continues with the parts described above. The
listing below is an simple example of an SCL-file (listed in Part 6[WG109a]:
<?xml version="1.0" encoding="UTF-8"?>
<SCL xmlns="http://www.iec.ch/61850/2003/SCL"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.iec.ch/61850/2003/SCL SCL.xsd"
version="2007" revision=?A?>
<xs:element name="SCL">
<xs:complexType>
<xs:complexContent>
<xs:extension base="tBaseElement">
<xs:sequence>
<xs:element name="Header" type="tHeader">
<xs:unique name="uniqueHitem">
<xs:selector xpath="./scl:History/scl:Hitem"/>
<xs:field xpath="@version"/>
<xs:field xpath="@revision"/>
</xs:unique>
</xs:element>
<xs:element ref="Substation" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="Communication" minOccurs="0"/>
<xs:element ref="IED" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="DataTypeTemplates" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="version" type="tSclVersion" use="required" fixed="2007"/>
<xs:attribute name="revision" type="tSclRevision" use="required" fixed="A"/>
10
</xs:extension>
</xs:complexContent>
</xs:complexType>
</SCL>
11
Chapter 3
Introduction to FACTS controllers
This report is in no way a complete introduction to power system controllers, but to understand the role of
FACTS power controllers a basic introduction is given. The presented theories are not defined here but only
given for background understanding. A source for a deeper introduction to FACTS Controllers is ThyristorBased FACTS Controllers for Electrical Transmission Systems by Mathur and Varma [MV02].
3.1
History and introduction to controlling power transmission
Historically the Alternating Current (AC) power system consists of generators, transmission and distribution
lines and loads. The generators, rotating synchronous machines, generate the power which is transmitted to
the load which consume the power, both real and reactive. The load may be synchronous, non-synchronous
and passive. The transmission line has an overall loop structure, where the distribution lines has a radial
structure providing the power to a defined load. In an AC system the current and voltage alternates in a
sinus wave, generally with a frequency of 50 or 60 Hz. As an example the nordic transmission grid system is
illustrated in Figure A.1.
The current and voltage changes depend on the load on the power system. By reactive (VAR) compensation
the described characteristics of the line can be changed depending on the load of the line. Traditionally shunt
connected reactors can be used to minimise over-voltage under light load conditions and shunt connected
capacitors can maintain voltage levels under heavy load conditions.
When transmission lines are long, series capacitive compensation can be used to shorten the ”electrical
distance”. This is done by reducing the inductive line impedance.
In multi-line systems it happens that the transmission angle of a line changes to a value outside the design
criteria for that line. To adjust the transmission angle of that line a phase angle regulator can be used. Phase
angle regulators are not discussed further in this work.
The emphasis of this report is on shunt technologies.
3.2
Shunt technologies of today
The Static VAR compensator or SVC uses thyristor based valves to control the amount of impedance or capacitance applied to the line. The SVC has no moving part as the synchronous compensators has, that’s why
it’s called Static VAR compensator. The static synchronous compensator or STATCOM uses a voltage source
converter to insert or reduce the reactive AC power of the power system. This gives a system with a much
higher switching capability compared to a SVC as the thyristor is bound to ”zero-crossing” for switching while
the voltage source converter can switch at any given moment.
SVCs and STATCOMs have different control modes as Voltage Control and Reactive Power Control. The
different modes are introduced in Section 3.4 and further described and modelled in Chapter 5
3.2.1
Thyristor based FACTS Controller
The SVC history starts in the 1970s. ABB was one of the pioneers and have been a market leader since then. A
SVC uses a combination of at least one thyristor valved controlled reactor or capacitor combined with harmonic
filters and mechanically switched reactor or capacitor banks to regulate the voltage level of a power system.
These elements of shunt connected units are usually called branches. The mechanically switched banks is used
for to increase the total reactive power support outside the dynamic range. The dynamic range is specified by
the size of the thyristor controlled reactors and capacitors. The rating of a SVC is given by the inductive and
12
Figure 3.2: A simplified single line diagram of a
STATCOM
Figure 3.1: SLD for the Extremoz SVC deliverd by
ABB to Mexico.
capacitive range in Mvar. For an example the rating of a SVC can be 75 Mvar inductive to 150 Mvar capacitive,
continuously variable (-75/+150).
A shunt connected FACTS device can have one or more thyristor controlled reactive components, usually
referred to as branches. There exist three types of Thyristor controlled reactive components listed in Table 3.1.
The shunt connected FACTS device usually also have one or more harmonic filters and control shunt connected
reactor or capacitors branches. Generally the passive, harmonic filters are used to improve voltage stability,
filter harmonics and lowering resonance problems. A single line diagram of an ABB multi-branch SVC with
harmonic filters is shown Figure 3.1.
Table 3.1: Thyristor controlled reactive components
3.2.2
Name
Thyristor Controlled Reactor
Abbreviation
TCR
Thyristor Switched Reactor
TSR
Thyristor Switched Capacitor
TSC
Comment
Reactance connected in series with a bidirectional
thyristor valve. The thyristor valve is phasecontrolled. Equivalent reactance is varied continuously. The current through the reactor is controlled
from full value to zero by adjusting the firing angle
of the gate between 90 and 180.
Same as TCR but thyristor is either in zero- or fullconduction. Equivalent reactance is varied in stepwise manner.
Capacitance connected in series with a bidirectional
thyristor valve. The thyristor control is either in
zero- or full-conduction. Equivalent reactance is
varied in stepwise manner. Switching a capacitor
leads to transient currents so to minimise this a capacitor is always switched when the voltage across
the switch is near zero. Therefor a thyristor switch
is only used to turn on or off a capacitor.
Converter based FACTS Controller
A shunt connected FACTS device can have one or more Voltage-Source Converter (VSC) components or
branches. A VSC can act as both as an inductive or capacitive component.Shunt connoted FACTS devices
that uses VSC-technolgy are generally called a Static synchronous Compensator (STATCOM). A Single Line
Diagram (SLD) example for a VSC can be seen in Figure 3.2.
13
Figure 3.3: Single line diagram of a Series Capacitor, showing Disconnector on the line, and By-pass
breaker in parallel with the capacitor.
3.3
Figure 3.4: Conceptual single line diagram of a
Thyristor Controlled Series Compensator.
Modern series technologies
The figures 3.3 and 3.4 shows simplified single line diagrams of the two common series compensating technologies, Fixed Series Capacitor (FSC) and Thyristor Controlled Series Compensation (TCSC). It exists a few
other technologies but they are very rare and is not covered in detail in this report.
A detailed single line diagram of a Fixed Series Capacitor is shown in the Appedix B.1.
3.3.1
Fixed SC
The application FSC uses a fixed amount of capacitors to reduce the impedance while the TCSC uses capacitors
together with a thyristor controlled reactor component so that the amount of impedance can be dynamically
changed.
Fixed series compensators, pioneered by General Electric in the 1930:ies, are by far the most used series
compensation, used on long power lines to reduce the electrical distance. The amount of capacitance can be
varied by dividing the capacitors to segments of the same or different size of capacitance. The logic behind
switching can be based on for instance the power flow of the line and the switching of this segments is done
by by-pass breakers controlled by a controller. This is a rather slow control where changes can be measured
in seconds. The switching is done by by-pass breakers, which by closing, by-passes the segments of the series
compensator to decrease the capacitance and by opening, of the same by-pass breaker, includes the segment
and by that increases the capacitance.
Capacitors are sensible to over current and over voltage so the capacitors are protected by an advanced
scheme of protection. The protection schemes may include varistors that is dimensioned so that they conduct
on a specific current level, triggered spark gaps that conduct on when the voltage between the gaps two
conductors exceeds the gap’s breakdown voltage or triggered by the control, and a controlled by-pass breaker.
The protection schemes are implemented in a control system where measuring points keeps track of currents,
energy level in the varistor and frequencies of the system, etc.
3.3.2
Thyristor Controlled Series Compensator
With the TCSC it is possible to change the impedance of the line much faster as the thyristor based controlled
component can switch in different impedance every cycle of the current.
The control modes of an TCSC are more advanced than for a FSC, an TCSC can be used not only for
compensating of long transmission lines but also for power flow control and Sub-synchronous Resonance
(SSR) mitigation.
3.4
Operating modes of a FACTS Controller
A FACTS controller can act in different control modes. The over all control is some way of control the voltage
of the power grid, this can be done either using the voltage or the current as reference. As the resulting impact
is on the grid voltage, both methods can be grouped in to ”voltage control”. More advanced features of a
FACTS controller can be reactive power control and power oscillation damping. Voltage control and the more
advanced features are described later in Chapter 5.
14
Chapter 4
Use case: SVC
For the use case I have chosen a SVC of generic size, with two thyristor controlled branches and two external
reactive components. Figure 4.1 shows the SLD of the SVC and the item designations of relevant components.
In this chapter I use SVC instead of FACTS Controller but from a modelling perspective it is equal, this use
case is relevant for other types of FACTS Controllers too.
Equipment that needs to be modelled but is not present in the SLD is the control and protection system of
the SVC. This chapter will go through communication and interaction interfaces and show needed modelling.
The coming chapters will analyse the process items for this use case.
Figure 4.1: Single line diagram of use case SVC.
4.1
Communication interfaces in a SVC
In Section 2.4 the different communication interfaces of IEC 61850 was introduced. The Figures 4.2 and D.1 has
been drawn to show the communication interfaces of the SVC use case. In Figure 4.2 I divided the interfaces
into three different categories:
Vendor specific. I have identified three interfaces of the SVC device: Control Signals, Indication and Sensors. In this part the communication is either part of the intellectual property of the vendor or the time
requirements are to high for IEC 61850 of today[WG113c].
One exception exist, the communication interface of sampled values and control data for substation relay
protection. The communication in this layer is described in IEC 61850-9-2.
15
The counterpart of the FACTS device interfaces is the three logical subparts of the control system: Monitoring, Control and Protection.
IEC 61850 Station Integration. The three logical subsystems of the control system has an interface towards the
substation, external devices in the same or other substations and other FACTS controllers. The communication methods introduced in IEC 61850-8-1 is used here, additionally the interface defined in IEC/TR
61850-90-1: Use of IEC 61850 for the communication between substations [WG110d] apply here.
Substation to Control Center. Includes the interfaces to and from the remote operators and EMS1 of the electrical network. When published, the interfaces defined in IEC/TR 61850-90-2: Using IEC 61850 for communication between substation and control centres might be applied.
The FACTS device and the three logical subsystems described above forms the FACTS Controller and its
control system.
The interface defined in the standard (Figure 2.3 and Table 2.1) is noted on the relations between the parts
in the Figure 4.2. From this mapping the interfaces for 1 – protection-data exchange between bay and station level,
6 – control data exchange between bay and station level, 8 – direct data exchange between the bays especially for fast
functions like interlocking, and 8 – control-data exchange between substations will be more explored in this report.
Figure 4.2: Communication interfaces for use case.
4.2
Analysis of use case
An operator, either from remote or local, interacts with the SVC by giving different commands and the operator
also receives events and indications from the FACTS controller. In Figure 4.3 the different use cases is shown.
At interaction level the user controls what Operating Mode the SVC is currently in. The Operating modes
are further described and defined in Section 5.1.1. Further the Operator configures the control mode of the SVC.
The difference between operating modes and control modes are discussed in Chapter 5, and the different control modes, Voltage Control, Reactive Power Control and POD Control is thoroughly described in Sections 5.2, 5.3
and 5.4. The same sections describes the different process data needed by the different control modes, and
other process data related to equipment is described in Chapter 7. Together with the different control modes
of the SVC, there are also Protection of the SVC. They are described and the process data for protections are
listed in Section 5.6.
1 Energy
Management System
16
Figure 4.3: Use case for Operators interaction and relationship between the SVCs functions.
17
Chapter 5
Operating and control modes of FACTS
Controllers
This chapter describes the different states of a FACTS Controller, three common control modes on how the
FACTS Controller interacts with the power grid and last interaction between parallel FACTS Controllers. While
describing the different control modes, different important parameters are listed to be used later in modelling.
5.1
Operating modes of FACTS Controllers
The operating modes of a FACST Controller is described in this section by showing how the FACTS Controller
operates and defining a state machine showing the different modes and the transitions between them.
5.1.1
Definition of a state machine for operating modes
Figure 5.1: The state machine describe the operating modes of a FACTS Controllers. Steady states are marked
with thicker frames and transient states with thiner frames.
A FACTS Controller has different states or modes of operation. A general view of states can be seen in
Figure 5.1. The figure does describe the state machine of a FACTS Controller, it does not describe the status of
the IED or control system used for controlling the FACTS Controller, nor does it describe the control modes of
the FACTS Controller.
The states can be described as follows:
18
Off | Trip The FACTS Controller is not active and in the current state, and conditions is preventing the device
to be put in to service. The transition to the state ReadyToStart is triggered by conditions based on status
for the equipment.
ReadyToStart The conditions needed to put the FACTS Controller in to operation are fulfilled. This conditions
include that no alarm is active, all target and lock-out relays are reset, grounding switches at FACTS
Controller bus are open, FACTS Controller disconnector switch is closed, grounding switches in each
available branch are open, disconnector switches in each available branch are closed and valve cooling
system is ready for start.
InOperation The FACTS Controller is started and running with given parameters for voltage control and
connected to grid.
The state machine also includes transition states or sequences of actions. They can be described as follows:
StartSequence By order from operator, the FACTS Controller is taking predefined actions to start the FACTS
Controller and connect to the grid. If the sequence finishes successfully the FACTS Controller will be in
state InOperation, on any failure a transition to the TripSequence state will occur. A predefined action in
this transition state is that the operator can issue a Cancel command. If this is done a transition to the
StopSequence-state will occur.
StopSequence By order from operator, the FACTS Controller is taking predefined actions to make a controlled
stop of the FACTS Controller and disconnect from the grid. When the sequence is finished the FACTS
Controller will be in state Off | Trip, and in under normal conditions a transition to the state ReadyToStart
will begin.
TripSequence In case of a non-recoverable fault the FACTS Controller is taking predefined actions to make
an immediate disconnection from the grid and a stop of the FACTS Controller. When the sequence is
finished the FACTS Controller will be in state Off | Trip.
Table 5.1: Operating mode and Operating location process data
Process information
Operation mode
Control Order
Sequence Status
Local control
Station control
Control locked to
local by key
Degraded operation
Type
Unit
Comment
enumeration
0: OffTrip;
1: ReadyToStart;
2: StartSequence;
3: InOperation;
4: StopSequence;
5: TripSequence
enumeration
0: Cancel;
1: ForcedStop;
2: Start;
3: Stop;
enumeration
0: NoSequenceRunnig;
1: SequenceRunning;
2: SequenceAborted;
Binary indication
Controllable Binary indication
Binary indication
-
The current operating state/mode.
-
Command selected by operator.
Binary indication
19
Sequence status :
Control Authority Local
Control Authority Station level
Control is switched to local, by physical key or logic switch
The control is running with reduced
capabilities.
5.1.2
Control locations
The FACTS controller, as any substation equipment, can be operated from different control locations. The
locations are usually identified as local, where the operation is done in front of the equipment, remotely from
a substation control room and finally remotely from a control center. For safety reasons substation equipment
can be locked, by key or logic, to only allow local operation. Indication of location is important process data
for the operators regardless if they work local or remotely. The needed process data is given in Table 5.1
5.1.3
Degraded mode
Some FACTS controllers can be configured in such way that operation can be supported with reduced capacity.
The reduction can be caused by faulty conditions, for instance that dynamic range of the controllable reactance
is reduced due to thyristor failure. This can be marked using a substate called Degraded operation. The fault as
such is registered by the faulty component and is tracked by the control algorithm as such. Table 5.1 includes
the data needed for this.
5.1.4
Relationship between different control modes and open loop control
The control modes described above are all in closed loop control mode, where Voltage control is the main mode
and Reactive Power control and POD is an additional controls. The control can also be set up in open loop, so
that the control of the FACST device is set to a fixed output. This mode is referred to as manual mode.
In the operational state InOperation described in Section 5 an operator can change between different configurations of control. In the Figure 5.2 the relationship between the control is drawn.
Figure 5.2: State machine describing the relationship between control modes of a FACTS controller.
5.2
Voltage control
The voltage control system is a closed loop system with control of the positive-sequence voltage or the measured transmission system voltage (Vmeas ) at the SVC/STATCOM bus. The voltage reference (VRef ) is the
desired voltage level of the power system. The range of voltage reference is set by VRef M in and VRef M ax respectively. The Slope or Droop, ideally the curve describing upper limit of the output of the SVC/STATCOM,
shown as the dashed line in Figure 5.4. In practice the slope is set as percentage of deviation from the Vref .
The Gain setting corresponds to the short circuit power of the network in MVA, the unit is 1/s2 . The voltage
control can also operate on the current, Isvc . Parameters are listed in Table 5.2.
20
Transmission
Voltage
Measuring
Circuit
Slope
Vmeas
- -
+
VRef
Measuring
Circuit
Imeas
∑
VE
+
Thyristor
Susceptance
Control
Voltage
Regulator
ISVC
VSR
Susceptance
Regulator
∑
BSET
+
Mech. Equip.
Control Logic
Figure 5.3: Typical block diagram of the Voltage Control for an SVC. Example from [MV02]
Table 5.2: Voltage Control process data
Process
information
Auto
Type
Unit
Comment
Control
-
VRef ,
VRef M in ,
VRef M ax
Isec , IvscM in ,
IvscM ax
QRef ,
QRef M in ,
QRef M ax
BRef ,
BRef M in ,
BRef M ax
Control (analog value)
Volt
Control for switching between automatic or manual mode of the control
The desired voltage reference, with
min an max-limits
Control (analog value)
Ampere
Control (analog value)
VAr
Control (analog value)
VAr
Slope,
SlopeM in ,
SlopeM ax
Gain,
GainM in ,
GainM ax
Vmeas
Setting
value)
group
(analog
Ratio
Setting
value)
group
(integer
Ratio
The desired susceptance reference,
with min an max-limits. If min = max
the output from the FACTS controller
is fixed. This setting is used to set
the control to a fixed output in manual
mode.
The ratio of the voltage change over
the SVC/STATCOM range and rated
voltage
The regulator gain
Volt
Measured voltage of power system
Analogue Setting
21
The current reference, with min and
max-limits
The desired reactive power reference,
with min an max-limits
5.3
Reactive Power Control
The reactive power control or regulator consists of two separate functions; slow reactive power or susceptance
regulator and external bank controllers.
5.3.1
Slow susceptance or VAr regulator
Sys
te
V
m lo
ad
1
2
3
ΔV
I_C
I_L
Figure 5.4: A VI-diagram showing the operating characteristic of a shunt connected FACTS device with slow
susceptance regulator. Figure is inspired by [MV02]
When the automatic voltage regulator controls the FACTS Controller, a superimposed reactive power control can also be activated. The FACTS Controllers reactive power output returns slowly to a pre-set steady-state
value, so that its var (usually in Mvar) capacity is held in reserve. The VI-diagram in Figure 5.4 shows in point
1 the output from the FACTS controller at a given system load. In point 2 the system load has decreased. The
response output from the FACTS controller is now closer to the edge of its capitative capability. If the state is
stable, the algorithm lowers the voltage reference, and by that increasing the response capability of the FACST
controller. When stabilised, point 3 represent the new steady state.
The slow susceptance or reactive power regulator is slow, compared to the voltage control, and its output
signal (∆VRP C ) is added to the voltage reference signal in such a way that in steady state the SVC/STATCOM
will remain within a susceptance / reactive power window defined by two limits, one at the capacitive range
and one at the inductive range. The needed process information is listed in Table 5.3, for an thyristor controlled
device, one can use the susceptance,B as set point, for a voltage converter device one can use the reactive
power,Q.
5.3.2
External banks
There might be other compensating components, such as reactor- or capacitor banks, in the same or nearby
substations which is used to increase the reactive ability of the FACTS controller. The modelling example
used in this report (see Figure 4.1) controls one Mechanically switched capacitor (MSC) and one Mechanically
switched reactor (MSR), and in the real life example shown in Figure 7.1 the STATCOM1 controls three external capacitor banks. MSR- and MSC-banks are used together with the slow susceptance or reactive power
regulator to achieve a situation where the steady-state reactive-power loading allows the SVC or STACOM to
have effective response to disturbances. The needed process information is listed in Table 5.4
5.4
Power Oscillation Damping mode
The Power Oscillation Damping (POD) control is provided by modulation of the voltage reference in dependence of a measured quantity in the transmission system, P (t). The selected input signal is typically active
1 SVC
Light(R) at Holly substation in Texas, USA, delivered by ABB in 2003
22
Table 5.3: Reactive Power Control process data
Process information
Reactive Power
Control
Type
Unit
Comment
Control
-
RPC Blocked
Control
-
Gain reset and
indication
of
gain reduced.
Control (Binary value)
Ratio
Gain
Setting Group (Float)
1/s2
Gain factor
BSET
Float
Analogue Setting
Percentage
VAr
QSET
Analogue Setting
VAr
∆VRP C
Float
Volt
Switch on or of the Reactive Power
Control, dependent on if the superior voltage control function is in automatic, if not this functions is not available and should be blocked.
Function is blocked by other function,
due to external requirements.
Indication that the gain is reduced by
the predefined setting. The control, Reset control, resets the gain to the predefined value.
The predefined reduction of gain setting
Percentage of full Gain
Susceptance set-point for Reactive
Power Control function, can not be set
if QSET is used.
Reactive power set point for Reactive
Power Control function, can not be set
if BSET is used.
Output from Reactive Power Control
Table 5.4: Process data for external banks
Process
information
Unit start
Unit active
Unit blocked
Type
Unit
Comment
Control
Binary value
Binary value
Boolean
Boolean
-
Control of unit. Switch in or out
Shows if units are active.
Shows if unit is blocked due to
decharging.
Control amount of reactive power.
VAr
Combined reactive power output
Increase/decrease
Control
VAr
Reactive
Analogue Value (signed)
power
23
Transmission
Voltage
Measuring
Circuit
P(t)
From Power System
POD Control
Slope
Vmeas
VP
Measuring
Circuit
Imeas
- -
OD
+
∑
Vref
VE
Thyristor
Susceptance
Control
Voltage
Regulator
+
ISVC
VSR
Susceptance
Regulator
∑
Mech. Equip.
Control Logic
BSET
+
Figure 5.5: Outline of SVC voltage control system with additional reference signal for POD
power flow or frequency deviation. The interface to the Voltage control is an additional Voltage reference,
∆VP OD . See Figure 5.5 for a schematic outline of the functionality. The needed process information is listed in
Table 5.5
Table 5.5: Process data for Power Oscillation Damping.
5.5
Process
information
POD-control
POD function Blocked
∆VP OD
Type
Unit
Comment
Control
Control
Boolean
Boolean
Analogue Value
Volt
P (t) active
power flow
P (t)
frequency
deviation
Analogue Value
P
Analogue Value
Hz
On/Off of POD mode.
Function is blocked by other function,
due to external requirements.
Additional Voltage reference from
POD-control
Input signal to POD control from
transmission system
Input signal to POD control from
transmission system
Parallel controllers
There might also be two or more co-located FACTS Controllers in the substation or nearby in the power grid.
In such cases, some kind of overall joint control is required to prevent the devices to counteract each other. The
needed process information is listed in Table 5.6
5.6
Protective control modes
Besides the described control modes described in this chapter, there is special protective control to protect the
power system equipment and power electronics.
5.6.1
Protection of FACTS controllers with power electronics
The substation protection used together with shunt connected FACTS controllers are common substation (relay) protections. Relay protection has been the main focus for the development of IEC 61850, and is well
24
Table 5.6: Process data for Parallel controllers.
Process
information
Vref
Type
Unit
Comment
Analogue set point
p.u.
Gain
Slope
Analogue set point
Analogue set point
%
Request to
optimise
Optimisation
prohibited
Binary control
-
Binary control
-
The voltage reference, normalised to
per unit
Current gain of the voltage control
Current Slope set point of the voltage
control
Normal operation or Request to start
optimisation
OK or prohibit optimisation
described in many reports among other the Cigré2 publication ”Applications of IEC 61850 Standards to Protection Schemes”[CIG13] so this report will not discuss relay protection of FACTS Shunt devices. The standard
defines the LN PTHF for thyristor protection but it is a logical node related to protection of generators. In
Table 5.7 and Table 5.8 the different protections are needed.
In the report I only cover the protection of thyristor based applications. The protection of converter based
FACTS applications is similar, and is more or less repetition of the thyristor protections, I have decided to leave
them for future work as they too is not covered by the standard in all details.
Table 5.7: Protection related to voltage control.
Protection Name
Primary Current Limitation
Service or information provided
Part of voltage control. The primary current from the SVC is limited by the SVC control system. Limiter in voltage control. Value,
and above value trigger an event. Process data:
IP rimLimit Limit value
tP rimLimit Time before event trigger
Reactive Power Limitation
Part of reactive power control. The capacitive/reactive power
from the SVC is limited by the SVC control system. The setting
level is determined by guaranteed capacitive/reactive power
output. Limiter in reactive power control. Value, and above
value trigger an event. Process data:
QLimit Limit value
tQLimit Time before event trigger
Secondary Voltage Limitation
Part of voltage control. In order to prevent the TSC valve and capacitors from overload at over-voltage conditions, the SVC control will limit the SVC bus phase-to-phase voltage. Value, and
above value trigger an event. Process data:
U2ndLimit Limit value
tU 2ndLimit Time before event trigger
5.6.2
Protection of Series compensation
The protection of Series Capacitors (SC) is well-defined in the International Standard IEC 60143-2 [TC312].
Table 5.9 lists the protection and actions related to each protection. By the same reason why the protection
control functions of VSC is left for future work, the modelling of SC-protections is also left for future work.
2 Cigré, the Council on Large Electric Systems, is an international non-profit Association for promoting collaboration with experts from
all around the world by sharing knowledge and joining forces to improve electric power systems of today and tomorrow.
25
Table 5.8: Protection of thyristor controlled reactive components
Protection Name
TCR current limitation
Service or information provided
In order to protect the reactors and the thyristor valves from overcurrent, the TCR is equipped with a current limiting control loop.
Value, and above value trigger an event. Process data:
IT CRLimit Limit value
tT CRLimit Time delay before operate
TSC Valve over-current protection
The over-current protection will prevent the thyristors from
blocking after a very high surge current, e.g., due to misfiring
of the thyristors. Process data:
IT SCLimit Limit value
tT SCLimit Time delay before operate
TSC Capacitor
Protection
Over-voltage
Usually called COVP, the protection will prevent the TSC from
switching out, reducing thus voltage stresses on the capacitor
bank and valve. Process data:
UT SCLimit Limit value
tT SCLimit Time delay before operate
TSC Valve Over-voltage Protection
Usually called VOVP, prevents the valve from firing at high overvoltages leading to valve over-current. Process data:
UT SCV alveLimit Limit value
tT SCV alveLimit Time delay before operate
Over-voltage Strategy
To protect valve and other components. Process data:
UOV SLimit Over voltage limit
tOV SLimit Time delay before operate
Synchronising Voltage Supervision
The synchronising unit is basically a Phase-Locked-Loop (PLL)
that is used for synchronising the firing pulse generators of the
thyristor valves with the SVC busbar voltage.
Usync Over voltage limit
tU sync Time delay before operate
Under-voltage strategy on the
auxiliary power
Monitors the auxiliary power supply for the cooling system. If
the voltage drops the valves can get overheated. The valve or
converter can run for a limited time, but if the condition continues the protection trips the FACTS controller.
U2:ndLimit Under voltage limit
tU 2:nd Time delay before operate
26
27
Lockout
Reinsertion
X
X
X
X
X
X
Temporary
block
insertion
X
Bypass
Function
Capacitor overload
Varistor overload
Sub-harmonic protection
SSR protection
Line current supervision
Capacitor unbalance
Flashover to platform protection
Varistor failure
Bypass gap failure
Bypass switch failure protection: close failure
Bypass switch failure protection: open failure
Bypass switch pole disagreement protection
Disconnector pole disagreement protection
Protection and control system failure
Flashover to platform
Alarm level
Table 5.9: Overview of typical series capacitor bank protections. Based on IEC 60143-2.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Chapter 6
Data modelling
In this chapter I will compile the information presented in previous chapters, and grouping the information
in to existing logical nodes by extending them with new data objects. Some properties will need new logical
nodes and they too are described in this chapter.
The tables used in this chapter describes the Logical Nodes suggested for mapping FACTS Controllers with
relevant Data Objects. The table columns is explained in the Table 6.1.
Table 6.1: Interpretation of logical node description tables
Column heading
Data object name
CDC
T
M/O/C
Description
Name of the data object
Common data class that defines the structure of the data object.
Either defined in this report or in the standard (Part 7-3)
Transient data objects — the status of data objects with this designation is momentary and must be logged or reported to provide
evidence of their momentary state.
This column defines whether data object is mandatory (M), optional (O) or conditional (C). If the data is defined with a C the
condition is given in a footnote to the table.
Additionally the data objects of a logical node is grouped in to different categories, as described below (as
defined in the standard):
Common logical node information is information independent of the dedicated function.
Status information is data which shows either the status of the process or of the function allocated to the LN
class.
Settings are data which are needed for the function to operate.
Measured values are analogue data measured from the process or calculated in the function.
Controls are data which are changed by the commands.
6.1
Substation level of a FACTS controller
A FACTS controller usually have an HMI for maintenance, commissioning and operations. This computer can
be at Station Level or Bay Level. A FACTS Controller can be a substation or part of a substation. When the
FACTS controller is the only installation at a substation it is usually the
The Figure 6.1 shows with the example of an SVC the different scopes of a FACTS Controller. One needs to
model substation equipment, logic (control and protection) and system state.
28
Figure 6.1: Mapping between real world FACTS and virtualization in IEC 61850.
6.2
Modelling logic and system state
6.2.1
Controlling operation modes of FACTS device
A logical node for modelling a system state or over-all control is missing in IEC 61850-7-4 Edition 2. There
are examples from modelling of hydro power stations [WG112b] 1 which addresses similar functionality. The
LN CPEM, Control of Power Electrical Machine is newly defined in this report. The LN describes the FACTS
system state, and has data objects as shown in Table 6.2 and Figure 6.2.
The CDCs ENCControlOrder and ENCOperationStates are enumerations as described in Figure 6.3.
Table 6.2: LN: CPEM — Control of Power Electrical Machine
DataObject Name
CtrOrd
UnitOpMod
UntDegrOp
AbstractLNCommon::
ControllingLN.LocKey
AbstractLNCommon::
ControllingLN.Loc
AbstractLNCommon::
ControllingLN.LocSta
1 IEC
CDC
ENCControlOrder
ENCOperationStates
SPS
SPS
T
M/O/C
M
M
O
O
SPS
O
SPS
O
Comment
See Section 6.2.1
See Section 6.2.1
Local key (ControllingLN)
Local control behaviour (ControllingLN)
Local control behaviour (ControllingLN)
61850-7-410 Edition 1: Basic communication structure – Hydroelectric power plants – Communication for monitoring and control
29
Figure 6.2: UML representation of new Cxxx nodes.
30
Figure 6.3: UML representation of new CDC
6.2.2
Voltage Control
The logical node AVCO is described in 7-4 as a logical node for a voltage controller, independent of the control
method being used. The existing logical node can be extended with the data objects listed in Table 6.3 to make
it complete for FACTS applications. In the proposal for UML-diagram in Figure 6.4 the extension of LN AVCO
is described as an inheritance by generalisation.
The settings and process data for voltage control (Table 5.2) and the primary current limitation and secondary voltage limitation listed in Table 5.7 provides the needed data.
6.2.3
Reactive Power Control
Modelling of the reactive power control, based on the process data presented in the previous chapters. The
new logical node ARPC is proposed.
6.2.4
Modelling of POD Control
Modelling of the POD, based on the process data presented in the previous chapters. The new logical node
APOD is proposed and defined as Table 6.5 shows. By the inheritance of functionality of AbstractLNsCommon::ControlLN the interface for control is derived. The close relationship between the new LN AVCO, ARPC
and APOD where AVCO controls the other two could suggest that ARPC and APOD should be named CRPC
and CPOD instead. I have decided to keep them as this due to the fact the C-node usually is not logic control,
rather simple action control by operator or triggered by action from protection. The UML-model of the new
A-nodes is shown in Figure 6.4
6.2.5
Modelling of Parallel Controllers
The use case of parallel controllers is described in Section 5.5. The LN HJCL defined in the namespace for
Hydro power plant (Part 7-410[WG112b]) has similar use case.
I suggest that a new LN is described as a C-logical node, CJCL. The data objects corresponds to the process
information listed in Table 5.6. Deriving from the abstract logical node AbstractLNsCommon::ControllingLN
provides the data objects needed for control interface and the process data specifies the functionality of parallel
controllers.
31
Table 6.3: LN: AVCO — Voltage Control
DataObject Name
AbstractLNsCommon::
AutomaticControlLN.Auto
†
CDC
SPC
T
LNGroupA::AVCO.VolSpt APC
O
ASpt
APC
C†
BSpt
APC
C†
QSpt
APC
C†
SlopeSpt
ASG SP
O
GainSpt
ASG SP
O
VolLin
LNGroupA::
AVCO.LimAOv
OpDlATmms
LNGroupA::
AVCO.LimVOv
OpDlUTmms
Op
MV
ASG
O
O
Comment
When stVal=TRUE the control
is operating in automatic mode,
otherwise the control is running
in Manual mode
See Table 5.2 mxVal=VRef ,
minVal=VRef M in ,
maxVal=VRef M ax
See Table 5.2 mxVal=Isec ,
minVal=IvscM in ,
maxVal=IvscM ax
See Table 5.2 mxVal=Bref ,
minVal=BRef M in ,
maxVal=BRef M ax
See Table 5.2 mxVal=QRef ,
minVal=VRef M in ,
maxVal=VRef M ax
See Table 5.2 setMag=Slope,
minVal=SlopeM in ,
maxVal=SlopeM ax
See Table 5.2 setMag=Gain,
minVal=GainM in ,
maxVal=sGainM ax
Measured Line Voltage Vmeas
See Table 5.7: IP rimLimit
ING
ASG
O
O
See Table 5.7: tIP rimLimit
See Table 5.7: U2ndLimit
ING
ACTTransient
O
O
StrLimAOv
ACD
O
StrLimVOv
ACD
O
See Table 5.7: tU 2ndLimit
Trip from function when the
time StrLimAOv has been true
exceeds OpDlATmms or the
time StrLimVOv has been true
exceeds OpDlUTmms. The trip
is self is issued by PRCC.
A fault has been detected (LimAOv is exceeded).
A fault has been detected
(LimVOv is exceeded).
AtMostOne{ASpt, BSpt, QSpt}
32
M/O/C
O
Table 6.4: LN: ARPC — Reactive Power Control
†
DataObject Name
RPCCtr
Common Data Class
SPC
T
M/O/C
M
BSpt
QSpt
APC
APC
C†
C†
DelVolRPC
ASG
O
GainFactSpt
GainCtr
SPS
SPC
O
O
AbstractLNsCommon::
FunctionLN.Blk
LimQOv
SPS
O
ASG
O
OpDlQTmms
StrLimQOv
ING
ACD
O
O
Op
ACTTransient
O
Comment
TRUE or FALSE to activate function. Table 5.3
Susceptance set-point. Table 5.3
Reactive power set point. Table 5.3
Output from Reactive Power
Control
Gain reset and indication of reduced gain. Table 5.3
stVal = true when the superior
function AVCO.Auto = false
Reactive Power Limitation, see
Table 5.2 QLimit
See Table 5.2: tQLimit
A fault has been detected
(LimQOv is exceeded).
Trip from function when the
time StrLimQOv has been true
exceeds LimQOv. The trip is self
is issued by the LN PTRC.
AtMostOne{BSpt, QSpt}
Figure 6.4: UML representation of new Axxx nodes.
33
6.2.6
Reinsertion-logic
When the protection of a series capacitor bank operates it closes a bypass-breaker (referenced as QS1 in Figure B.1), and by that bypasses the capacitor bank. When conventional relay or line protection trips it opens a
breaker to isolate the fault. The implication of that is that the syntax for describing the automatic reinsertion
is the opposite of Autoreclose. For example when LN for Autoreclose (RREC) defines reclose time, reclose cycles , etc. A proposed LN for reinsertions, RRIN defines reinsertion time, reinsertion cycles where reinsertion
means opening of breaker after a specified time.
The UML-diagram in Figure 6.5 shows the suggested logical node and its relationship to the definitions in
Part 7-4.
Figure 6.5: UML representation of new RRIN node.
6.3
Modelling of Protection control modes
The Protection Control modes described in Section 5.6 and the needed process data can be divided in to two
groups: Current and Voltage protection of power electronics not covered by the standard and Voltage protection where existing LN can be applied. The following LN are proposed for modelling:
PRCC Current protection of Thyristor controlled Reactive Component, a new logical node described in Table 6.7. PRCC is defined deriving from CurrentProtectionLN defined in [Kos14].
PTRV Voltage protection of Thyristor controlled Reactive Component a new logical node described in Table 6.8. PTRV is defined deriving from VoltageProtectionLN defined in [Kos14].
PTUV Existing LN for Under-voltage strategy on auxiliary power.
PTUV Existing LN for Synchronising Voltage Supervision, is also an under voltage strategy.
Protection of VSC branches for STATCOM applications are similar to the above presented protections, and is
left for future work.
34
Table 6.5: LN: APOD — Power Oscillation Damping Control
DataObject Name
ActPwrFlw
HzDv
DelVPodSpt
PodCtr
Common Data Class
APC
APC
APC
SPC
T
M/O/C
C
C
O
M
Comment
See Section 5.4
See Section 5.4
Output from POD function.
If true the function is enabled
Table 6.6: LN: CJCL — Control of parallel FACTS Controllers
DataObject Name
VolSpt
GainSpt
SlopeSpt
CtlReq
BlkReq
Common Data Class
ASG
ASG
ING
SPC
SPC
T
M/O/C
M
M
M
M
M
Comment
Voltage reference, normalised to per unit.
The gain of the voltage control.
The slope of the voltage control.
Request optimisation control.
Block optimisation control.
Table 6.7: LN: PRCC — Current Protection of Thyristor Controlled Reactive Component
DataObject Name
LimATCR
LimATSC
OpDlTCRTmms
OpDlTSCTmms
Common Data Class
ASG
ASG
ING
ING
T
T
T
M/O/C
M
M
M
M
Comment
See Table 5.7:
See Table 5.7:
See Table 5.7:
See Table 5.7:
IT CRLimit
IT SCLimit
tT CRLimit
tT SCLimit
Table 6.8: LN: PTRV — Voltage protection of Thyristor controlled Reactive Component
DataObject Name
StrValCO
StrValVO
StrValOVS
OpDlCOTmms
OpDlOVSTmms
OpDlVOTmms
Common Data Class
APC
APC
APC
ING
ING
ING
T
T
T
T
35
M/O/C
M
M
M
M
M
M
Comment
See Table 5.7:
See Table 5.7:
See Table 5.7:
See Table 5.7:
See Table 5.7:
See Table 5.7:
UT SCLimit
UT SCV alveLimit
UOV SLimit
tT SCLimit
tOV SLimit
tT SCV alveLimit
Figure 6.6: UML representation of new Pxxx nodes.
36
Chapter 7
Analysing and modelling of Single Line
Diagram objects
Figure 7.1: Example Holly STATCOM, Texas 80 Mvar inductive to 110 Mvar capacitive.
This chapter describe the information communicated from items drawn on a SLD to the operator. The
primary use for information from sensors like CTs and VTs are of course providing the control system with the
right process information. But the information is also used for the operator to indicate positions of breakers
and measured values from sensors.
Other information like ratings and settings is properties that necessarily is not used for the process control as such, but is only registered once and then used as constants for the control or documentation for the
operators.
7.1
Mapping of traditional SCADA signal list items to IEC 61850, modeling Bottom-up
Both when using IEC 61850 and traditional SCADA protocols like IEC 60870-5 and DNP a document referred
to Signal list can be used. The Signal list is used to define peer-to-peer communication interface between
IEDs and operator interaction points like substations control rooms or control centres using . The signal lists
provides a subset of signals available in IED or control systems for the equipment, and vendor and user agree
upon which signals to communicate. At least four kind signals are usually defined: binary- and analogue
indications, settings and control commands.
37
For primary equipment as the ones drawn on SLDs, I have used SCADA-lists for collecting information on
what process information is of interest for operators. The input from ABB FACTS delivery projects has been
very useful.
Binary indication IEC 61850-7-3 defines common data classes (CDCs) for single and double point status. They
can be used to indicate state changes for instance.
Analogue indication There exists CDCs for different kind of analogue status information, for example integer,
enumeration, histogram and strings. A special kind of analogue status is measured values and the standard defines different kind of CDC for measured information like complex measured values, sampled
values, 3-phase values , etc.
Control orders and commands Objects that can be changes are referred to as status settings and the standard
defines settings for a large set of different data types, for instance single points, integers, time and analogue settings. Commands are typically specified as control orders. The IEC 61850 standard support
command sequences like ”select-before-execute”.
7.2
Modelling primary equipment
The primary equipment used in a FACTS Controller is to a great extent already described in IEC 61850, in this
section I show how this equipment can be and usually is modelled.
7.2.1
Indication and Control of Breakers and Switches
The indication and control of breakers and switches are well described in IEC 61850. No further description or
addition is needed for FACTS Controllers, with one exception in the specific protection function of a Spark gap
or Fast Protective device. This use case is described in Section 7.6 of this chapter.
7.2.2
Metering and Measured values
Measured values for instance values from VTs and CTs in or associated with the FACTS Controller shall be
modelled with the appropriate M-logical node described in Part 7-4 [WG110c].
7.2.3
Power Transformer
Shunt connected FACTS Controllers like SVCs and STATCOMs is usually connected on a lower voltage level
than voltage level of the transmission system. A power transformer is connected on the higher voltage level
and transforms the voltage to the FACTS bus voltage, the transformer is sometimes referred to as Step up
transformer The modelling of power transformers are well described in IEC 61850 and from a FACTS Controller
perspective no additional modelling is required.
In the use case presented in Chapter 4 the power transformer is called named Main transformer and drawn
in Figure 4.1 as =SVC.T1.
7.3
Branches of shunt connected FACTS Controller
The different branches described in Section 3.2 is modelled in this section.
7.3.1
Supervision of Power Electronics
The power electronics used in FACTS applications are grouped together in stacks. Each power electronic unit
(thyristor, IGBT, etc.) is generally controlled by an external control unit. This control unit triggers (turns on
and, if possible, turns off) and monitors one or more power electronic devices and is supervised for its health
status. The tracked health status are at least {OK, Failed, Communication failure}. The idea behind using
stacks are that by connecting the power electronics in series one can build units that are rated for a higher
voltage than each power electronic unit and to gain a redundancy for faults (if one small unit in a large stack
fails the reactive component can still be used but if one large unit would fail the reactive component would be
useless).
Simplified and small example for thyristor based reactive component:
If each thyristor has a rated maximum voltage of 2 kV, by combing 8 we have a stack that have a
rated maximum voltage of 16 kV. The thyristor valve is connected in a Delta-configuration between
38
the phases. That gives a set of 6 stacks {AB+, AB-, BC+, BC-, AC+, AC-}. In such configuration the
number of thyristors to monitor would be 6 ∗ 8 = 48. In addition to this, a number of thyristors
would be added to each stack for redundancy.
When designing the size of the stacks there are several parameters to consider. One big factor is the decided
voltage on the secondary bus (below the power transformer). One strive to optimise this secondary voltage to
be a combination of the size of the power transformer and the size of the stacks. It is not uncommon that this
results in several hundred of thyristors to monitor. The same architecture is used for HVDC application where
the numbers of thyristors reach several thousands.
7.3.2
Reactive Branches
Common for the controlled reactive components (TCR, TSR, TSC and VSC) is the use of power electronics
(thyristors, IGBT’s, etc.) to set the amount of reactive power of the component. As described in Section 7.3.1
the number of units to supervise can grow in to thousands of units. If one should model each power electronic
unit with a logical node, one should soon have logical devices consisting of thousands of logical nodes. This
is not feasible, and the smallest unit that is feasible is model is then stacks. It is today common to represent
the status of thyristors of at stack as a set of bit patterns. There is no data type defined for bit wise operations
in IEC 61850-7-2 [WG110a]. Neither is there any type of equipment with this kind of complexity in the Hydro
power (Part 7-410[WG112b]) or DER (Part 7-420[WG109b]) domain.
This report presents a way of using the defined CommonACSIType ARRAY to represent bit patterns to hold
the status of the individual units.
The ARRAY type of IEC 61850 is defined in Part 7-2[WG110a] as:
ARRAY
with
0...m
m
p=
OF p
≥0
GenCommonDataClass that does not contain an array type or
GenDataAttributeClass or
GenContructedAttributeClass or
TypeDefinitions (except ARRAY type)
As listed in Section 7.3.1 the status of each unit is tracked, the status can be enumerated {OK, Failed,
Communication failure}. Each status can be represented by a binary value TRUE or FALSE. Using the data
type Coded enum for the enumeration the size of the data type will be three bits. The new enumerated data
attribute type PEUnitStatus is defined.
The size of the array for units is determined by the number of stacks and the number of units per stack.
The size shall be defined as below:
NumStack
=
m≥1
NumUntStack
=
n≥1
NumUnt
=
n∗m
The status of a single unit can then be described as a function
Status(x, y)
where x
y
=
ARRAY[x ∗ y],
≤ NumStack
≤ NumUntStack
The definition a common data class on the base of the above is provided in Table 7.1. The new CDC extends
BasePrimititveCDC.
The branch is connected to a bus on the secondary side of the main transformer. The connection is usually
done with a controllable Circuit Breaker and as part of the Start-, Stop- and TripSequences (discussed in Section 5.1.1) the control system closes or opens this breaker. The information on if the branch is the connected or
disconnected to the bus needs to be communicated both to the control system and the operators.
Another process information is whether the redundancy of power electronic units is still valid. As mentioned in the section above when designing the stacks additional units are added for redundancy. A data
object to indicate for the operator that the redundancy level has changed and one data object to indicate that
the redundancy is lost is added.
If the valve loses the redundancy capability and cannot perform the control of the reactive power the branch
needs to be disconnected from the bus. This is done by starting the TripSequence.
39
Table 7.1: CDC: VST — Valve Status Common Data Class
Data attribute
Name
VlvVal
NumUnt
NumStack
NumUntStack
maxUnt
Type
FC
TrgOp
ARRAY
of
0
maxUnt-1
OF
CODED ENSPEUnitStatus
INT16U
INT16U
INT16U
INT16U
ST
dchg
Value
M
1 < NumPts ≤ maxUnt
≥1
≥1
CF
CF
CF
CF
M/O/C
M
M
M
M
Table 7.2: Process data for Reactive Component Branch
Process information
Branch connected to
the bus
Reactive Power rating
Type
Boolean
Unit
-
Comment
The connection status of the branch
Analogue setting
VAr
Voltage Rating
Analogue setting
Volt
Redundancy level
Analogue setting
Valve unit status
Data structure
-
Trip due to loss of redundancy
Boolean
-
Cooling system Type
Enumeration
-
The reactive power rating for the
branch, for information purpose.
Voltage rating of the branch, for information purpose.
The number of redundant semiconductors in the Valve
The status of units in the valve, independent of type semi-conductor used.
A trip caused by losing the redundancy of semi-conductors, independent of type semi-conductor used.
Type of cooling method (as in IEC
61850-7-420 [WG109b])
40
7.3.3
Thyristor controlled Reactive Component branches: TCR, TSR and TSC
A thyristor controlled reactive component consist of at least; a capacitive or inductive component, a thyristor
valve (usually in a Delta-configuration of the three phases as described in the example if Section 7.3.1), and
a current transformer. The functionality of the three different kind of branches (TCR, TSR and TSC) where
introduced in Section 3.2 and Table 3.1. If the capitative component consists of capacitors connected in an
H-bridge configuration, an additional CT is included for indication of unbalance current. Detailed examples
SLDs of a TCR and a TSC is provided in Appendix C to extend the use case SLD discussed above.
I propose that the CTs shall be modelled as described in the standard, with the logical node MMXU.
The protective control functions described in Section 5.6 and modelled in Section 6.3 is closely associated
with the components in the thyristor branch, the CTs provides current level input for the protection and output
from the protection control function provides information to the valve control. The protective control functions
are different between the three branch types, from a modelling perspective it’s therefor necessary to keep track
of the type. The modelling of type is also important for the operators.
When disconnecting an TSC from the bus, the capacitors of the branch can be charged. As long as the
capacitors have not discharged, the branch cannot be reconnected to the bus. The branch is therefor blocked
for a time-period while the capacitors dischargees.
The standard defines a logical node ZTCR for modelling of ”Thyristor controlled reactive component”.
Neither Part 5 or 7-4 gives a lot of information on how the LN should be used. Part 5 indicates that ZTCR
”Controls reactive power flow”. The data objects of ZTCR is restricted to only the mandatory objects: EEName
for External equipment name plate, EEHealth for External equipment health, OpTmh for Operation time.
As described above, the thyristor valve is built around thyristor stacks, serial connected thyristors triggered
by an external source. The process information needed is listed in the Table 7.3
Table 7.3: Thyristor controlled Reactive Component process data
7.3.4
Process
information
TCR type
Type
Unit
Comment
Enumeration
-
Branch
blocked due
to discharging
Discharging
time of the
capacitors
Boolean
-
The type of thyristor reactive component
Connection of branch is blocked
Measured value
-
The amount of time left until reconnection of branch is unblocked
Reactive component branch with a Voltage Source Converter: VSC
As described in Section 3.2.2 the Voltage-Source-Converter use a DC to AC Converter as source for reactive
power. As in the case with thyristor branch, the VSC-branch has sensors as CTs that provide information for
the process control. Also specific protective control modes, protecting the VSC-branch needs to be modelled
as in the case with the protections of a thyristor based reactive component.
7.3.5
Logical nodes for Reactive Components Branches
When modelling reactive branches, I have added an abstract logical node that collects the process data that
is common for both converter and thyristor based reactive branches. The abstract LN ReactiveComponentBranchLN is described in Table 7.5.
The logical node ZTCR derives from the abstract LN ReactiveComponentBranchLN and serves as an base
for all the three types of thyristor controlled or switched reactive component. Adding an enumeration for
the TCR type to the list of process data is therefor necessary. This is done by the new CDC ENGThyristorBranchFunction, derived from the CDC ENG, where values are restricted to an enumeration. In this case the
enumeration is defined as {Undefined=0, TCR=1, TSR=2, TSC=3}.
As discussed in Chapter 3.2.2 the VSC uses a power converter as reactive power source. The LN ZCON
is used to define a Converter. It has two settings VArRtg for the rated bisectional Vars and VRtg for the
rated voltage. In the work for the domain DER two more logical nodes has been defined for converter related
devices, ZRCT for the characteristics of a rectifier and ZINV for the characteristics of an inverter. In the work
41
Table 7.4: Voltage Source Converter process data
Process
information
Rated Voltage
Rated Active
Power
Branch connected
Valve units
status information
Branch
blocked due
to discharging
Discharging
time of the
capacitors
Type
Unit
Comment
Analogue setting
Volt
Analogue setting
VAr
Boolean
-
data structure
-
as discussed in Section 7.3.2
Boolean
-
Connection of branch is blocked
Measured value
-
The amount of time left until reconnection of branch is unblocked
Table 7.5: Abstract LN - ReactiveComponentBranchLN
DataObject Name
VRtg
VArRtg
BraDscon
VlvSt
RedLev
RedTrip
Common Data Class
ASG
ASG
SP
VST
ING
SPS
T
M/O/C
O
O
O
O
O
O
Comment
Rated Voltage
Rated Bidirectional VArs
Branch Disconnected
Valve unit status
Redudancy level of the vale
Tripsignal when redundancy is
lost
Table 7.6: LN: ZTCR - Thyristor controlled reactive component
DataObject Name
TcrTyp
Common Data Class
T M/O/C
ENGThyristorBranchFunction O
DschTmms
DschBlk
MV
SPS
O
O
42
Comment
Enumeration defined in Figure
6.3
Discharge timer
Reconnection of branch is
blocked due to discharge
for the amendment to Part 7 called Edition 2.1 it is discussed if the LN ZCON should be removed[Kos14]. The
three logical nodes does not very well describe the characteristics of a VSC-branch of shunt connected FACTS
Controller. Neither is it a good idea to use the LN ZTCR as the logical node implies a thyristor controlled
component and the VSC uses other kind of semi-conductors.
Instead I propose the new logical node LN ZVSC, derived from the newly defined abstract logical node
ReactiveComponentBranchLN. The LN is showed in the UML-diagram in Figure 7.2
7.4
Harmonic Filter
A shunt connected FACTS device usually have one or more Harmonic Filters. The harmonic filters are represented by a fixed var-rating, rated voltage and discharge timer.
One could use the LN ZCAP or eventually the LN ZREA to represent the harmonic filter as they share some
properties, but I suggest that a new LN is constructed to represent harmonic filters. My motivation for this is
that neither ZCAP or ZREA is constructed with harmonic filters in mind.
The suggestion of data objects for the new LN ZHAF is showed in Table 7.7 and UML-diagram in Figure 7.2.
Table 7.7: LN: ZHAF — Harmonic Filter
DataObject Name
VRtg
VArRtg
DschTmms
DschBlk
AbstractLNsCommon:
CmdEquipmentInterfaceLN.DschBlk
7.5
Common Data Class
ASG
ASG
MV
SPS
SPC
T
M/O/C
O
O
O
O
O
Comment
Rated Voltage
Rated Bidirectional VArs
Discharger Timer
If true the filter is blocked
If true all functions of the LN has
been blocked
Mechanically switched reactive components
The external capacitor and reactor banks are described in Part 7-4 with the two logical nodes ZREA and
ZCAP. ZREA has attributes for rated current (ARtg:ASG), voltage (VRtg:ASG), power (VArRtg:ASG) and
apparent power (VARtg:ASG). The attributes for ZCAP includes if the capacitor bank is blocked due to discharging(DschBlk:SPS) and if the capacitor bank is closed(CapDS:SPC). One data attribute for indicating if the
device is active has to be added for information interchange between the device, control system and operator,
(DevAct:SPC).
In Part 5, Annex A, its described how the information flow can be configured for reactive control of a
reactive rotating component and the LN ARCO is used.
I suggest that the LN ARCO also should be used for representing the control of one or more switched reactive in conjunction with the LN ARPC in FACTS Controller. The attribute for tap position (TapChg:BSC) can
used for switching control of the banks. The extension of the LN ZREA and LN ZCAP is shown in Figure 7.2.
7.6
Fast protective device and by-pass gap
Capacitor banks need to be insulated from the ground and shall also withstand all line current. A practical and
economic solution for that is to bypass the capacitor if harmful currents are detected. This can be done by a
by-pass gap, usually called Spark gap, or a fast closing device and they are triggered by the control system or
self-triggered by for instance the current level. This kind of protective schema is usually used in combination
with an MOV protective scheme. When a spark is triggered the harmful currents flows through the gap and
by that protects the capacitors.
This kind of power system device is not described by IEC 61850. The protection scheme for both kind of
types are comparable, and the process data can be combined.
7.6.1
Use case for Spark gap or Fast Closing Device
Based on the use case in Figure 7.3 the new logical node XFPD is defined to represent the device, SFPD to
represent the supervision of the device and the protection scheme is modelled in the new logical node PFCD.
43
Figure 7.2: New LN Zxxx to represent SLD objects described in this report.
44
The LN XFPD is described in Table 7.8 and the LN PFCD is introduced in Figure 6.6. The LN SPFD derives
its properties from AbstractLNsGroupS::SwitchgearSupervisionLN as shown in Figure 7.4
Figure 7.3: Use case for Spark gap or Fast Protective Device
Table 7.8: LN: XFPD — Fast Protective Device
DataObject Name
ARtg
VRtg
Common Data Class
ASG
ASG
45
T
M/O/C
O
O
Comment
Rated Current
Rated voltage
Figure 7.4: LN: XFPD to represent Fast Protective Device or Spark Gap
46
Chapter 8
Modelling of Distributed Energy
Resources (DER), Wind and Hydro power
plants
8.1
New domains with-in IEC 61850
The domain of IEC 61850 started modelling substations for transmission- and distribution systems and the
communication within substations. The domain has been extended to include also communication between
substations, communication between substations and control centres. Three other major domains which have
been modelled with IEC 61850 is Wind power plants (IEC 61400-25), Hydro power plants (IEC 61850-7-410)
and Distributed Energy Resources (IEC 61850-7-420).
Compared with the three later three domains, the FACTS domain represent a smaller domain. The number
of physical units modelled in the other domains are greater.
8.1.1
DER
The DER work present logical nodes for management and generation systems, specific types of DER and
auxiliary systems. The DER domain addition was first published in 2009 as International Standard IEC 618507-420[WG109b]. It was a done by the WorkGroup 17 with-in TC 57, who now work with an update of the
standard.
The standard included almost 40 new logical nodes and even more derived CDCs.
8.1.2
Hydro power plants
The extension of IEC 61850 with modelling of Hydro Power Plants where first published in 2007 and then
revised with Edition 2 in 2012 as the International Standard IEC 61850-7-410. Another contribution by Work
group 18 of IEC TC 57 was a Technical Report published 2012, IEC/TR 61850-7-510[WG112c], containing modelling concepts and guidelines. The Hydro-standard is more or less equal in size to the DER-standard adding
a large number of logical nodes.
8.1.3
Wind power plants
The Technical Committee 88 (TC88, Wind turbines) developed the International Standard IEC 61400-25 ”in
order to provide a uniform communication basis for the monitoring and control of wind power plants”[TC806].
First published in the IEC 61400-25 was the four parts: 25-1: Overall description of principles and models, 25-2:
Information models , 25-3: Information exchange and 25-4: Mapping to communication profile. Additionally
two more parts have been released (5 and 6) and there is a task force working with Edition 2.
8.1.4
Other domains where modelling is needed
Within TC57 WG10 there is several task forces working with to extend the domains of IEC 61850 for instance
the communication between substations and control centres (Task-force 90-2), Energy Storage (TF 90-9) and
the one most relevant for the work in this report TF 90-14: Modelling FACTS, HVDC and Power Conversion
with IEC 61850.
47
8.2
Comparison and influences
The three figures 8.1, 8.2 and 8.3 gives an over view of the three domains DER, Hydro and FACTS. All three domains contains control over physical equipment and have different modes of operations. The also share power
electrical equipment of same kind, where none was described in the original version of IEC 61850. Equally the
process, complex logic and control modes was not described. Similarities looks obvious, for instance control
modes is shared with Hydro and DC Converter with DER, but the different domains have also differences.
The FACTS domain has less physical devices and all equipment is static, where the two other domains have
devices like turbines and flywheels.
Figure 8.1: Simplified network of a hydropower plant. Figure is part of IEC/TR 61850-7-510.
Figure 8.2: Conceptual organisation of DER logical devices and logical nodes. Figure is part of IEC 61850-7-510.
When studying the DER closely, the differences in application comes more clear. DER is an active power
source, where the FACTS controller consumes or produce reactive power. The primary function for the DC
converter for an DER (modelled as LN ZINV) is converting from DC to AC, where the converter part of an
VSC is a source for reactive power. They share some properties, for instance cooling but the other properties in
48
ZINV reflect that the ZINV is not suitable to represent a VSC. If details about the converter status is important
to the operator, the LN ZINV can be used together with the LN ZVSC proposed in this report (see Section 7.3.4)
as they share very few data objects and they are defined as optional.
Figure 8.3: Model of FACTS Controller and virtualisation in IEC 61850 as described in this report.
In the Hydro-domain it’s described a logical node for join-control of power plants, called AJCL. The jointcontrol is described in Part 7-410 [WG112b] as
”... The joint control function will normally try to optimise the power production between units
already in operation...”
which is very similar to the use case of parallel FACTS controllers described in Section 6.2.5.
49
Chapter 9
Conclusions
I have in this report described a proposal on how to model the power system application FACTS using the
International Standard IEC 61850, and my conclusion is that the requirements of the FACTS application shows
that additional logical nodes are required and furthermore, other extensions of the IEC 61850 standard is
needed.
This I have done by introducing the FACTS application with use cases of operation states and different
control modes. I have shown the different configuration and control strategies that needs to be modelled and
identified the process data for settings and status indications of control strategies and equipment. Additionally
the communication interfaces of a FACTS Controller has been described, and a mapping of the communications interfaces defined in IEC 61850 has been done and is shown.
The report also introduces how the standard describes the process of modelling process data and how
to group the data in to the levels data attributes, data objects, logical nodes and logical devices. I have investigated the supervision of the reactive components for shunt connected FACTS controllers like SVCs and
STATCOMs and constructed a proposal on how to efficient monitor the vast amount of power electronics used
in those components.
With the bases in the described modelling principles and using the FACTS application Static VAR Compensator, SVC, as use case I have done the modelling partly by showing where existing logical nodes can be used,
partly by defining new logical nodes and new common data classes, and finally by adding new data objects to
logical nodes described in the parts 7-4, 4-410 and 7-420 of IEC 61850.
I have done the modelling in UML using the UML-model that is used for describing all of Part 7 of IEC
61850.
When investigating other domains of power system application that have been modelled with IEC 61850 I
have found similarities in the domains which have contributed to the way I have proposed the modelling of
FACTS.
9.1
Future work
I have left some items for future work, this include items where the work would have been only repetition
of work already done like specifying the protection for converter based reactive components and protection
of Series Capacitors. The power system application of FACTS Controllers is still growing and new control
strategies and protection schemes is in development. I have tried to be general in my descriptions and by
using well defined control strategies and protection schemes I think that the FACTS domain is well covered in
this report, but new technologies might need additional modelling.
50
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[Bla07]
John Black. Draft iec 61850 communication networks and systems in substations, 2007.
[CIG13]
Applications of IEC 61850 Standards to Protection Schemes. Cigré Working Group B5.36, June 2013.
[Ger12]
Juan Gers. A primer on iec 61850 grid data communications, 12 2012.
[Kos14]
T. Kostic. Package for uml model of iec61850-7-* ed.2, 08 2014.
[KWU+ 06] B. Kasztenny, J. Whatley, E.A. Urden, J. Burger, D. Finney, and M. Adamiak. Jec 61850 - a practical application primer for protection engineers. In Power Systems Conference: Advanced Metering,
Protection, Control, Communication, and Distributed Resources, 2006. PS ’06, pages 18–50, March 2006.
[MV02]
R.M. Mathur and R.K. Varma. Thyristor-Based FACTS Controllers for Electrical Transmission Systems.
IEEE Press series on power engineering. Wiley, 2002.
[Nor08a]
Daniel E. Nordell. Communication system characteristics part 1. IEEE PES DA Tutorial, July 2008.
[Nor08b]
Daniel E. Nordell. Communication system characteristics part 2. IEEE PES DA Tutorial, July 2008.
[RM]
SISCO Inc. Ralph Mackiewicz. Benefits of iec61850 networking. UCA International Users Group.
[TC312]
IEC TC33. IEC 60143-2: Protective equipment for series capacitors banks. IEC, 2.0 edition, 12 2012.
[TC590]
TC57. IEC 60870-5. IEC, 1.0 edition, 02 1990.
[TC806]
IEC TC88. IEC 61400-25-1: Wind turbines – Part 25-1: Communication for monitoring and control of
wind power plants – Overall description of principles and models. IEC, 1 edition, 12 206.
[WG109a] IEC TC57 WG10. IEC 61850-6: Configuration description language for communication in electrical substations related to IEDs. IEC, 2.0 edition, 12 2009.
[WG109b] IEC TC57 WG17. IEC 61850-7-420: Basic communication structure – Distributed energy resources logical
nodes. IEC, 1.0 edition, 3 2009.
[WG110a] IEC TC57 WG10. IEC 61850-7-2: Basic information and communication structure – Abstract communication service interface (ACSI). IEC, 2.0 edition, 2010.
[WG110b] IEC TC57 WG10. IEC 61850-7-3: Basic communication structure – Common data classes. IEC, 2.0
edition, 12 2010.
[WG110c] IEC TC57 WG10. IEC 61850-7-4: Basic communication structure – Compatible logical node classes and
data object classes. IEC, 2 edition, 2010.
[WG110d] IEC TC57 WG10. IEC/TR 61850-90-1: Use of IEC 61850 for the communication between substations.
IEC, 1 edition, 03 2010.
[WG111a] IEC TC57 WG10. IEC 61850-4: System and project management. IEC, 2 edition, 04 2011.
[WG111b] IEC TC57 WG10. IEC 61850-7-1: Basic communication structure - Principles and models. IEC, 2.0
edition, 07 2011.
[WG111c] IEC TC57 WG10. IEC 61850-9-2: Specific communication service mapping (SCSM) – Sampled values
over ISO/IEC 8802-3. IEC, 2 edition, 09 2011.
[WG111d] IEC TC57 WG10. IEC 68150-8-1: Specific communication service mapping (SCSM) – Mappings to MMS
(ISO 9506-1 and ISO 9506-2) and to ISO/IEC 8802-3. IEC, 2 edition, 06 2011.
51
[WG112a] IEC TC57 WG10. IEC 61850-10: Conformance testing. IEC, 2.0 edition, 12 2012.
[WG112b] IEC TC57 WG18. IEC 61850-7-410: Basic communication structure – Hydroelectric power plants – Communication for monitoring and control. IEC, 2 edition, 2012.
[WG112c] IEC TC57 WG18. IEC 61850-7-510: Basic communication structure – Hydroelectric power plants – Modelling concepts and guidelines. IEC, 1 edition, 3 2012.
[WG113a] IEC TC57 WG10. IEC 61850-1: Communication networks and systems for power utility automation –
Part 1: Introduction and overview. IEC, 2 edition, 2013.
[WG113b] IEC TC57 WG10. IEC 61850-3: General requirements. IEC, 2 edition, 12 2013.
[WG113c] IEC TC57 WG10. IEC 61850-5: Communication requirements for functions and device models. IEC, 2.0
edition, 01 2013.
52
Glossary
bay subpart of a substation, having some common functionality, closely connected to the other subparts, and
forming a substation. 7
CT A current transformer is used for measurement of alternating electric currents.. 4, 7, 37, 38, 41
GOOSE Generic Object Oriented Substation Events. 1, 4
GSE Generic Substation Events. 4
GSSE Generic Substation State Events. 4
HMI Human Machine Interface, point of interaction for users of the equipment.. 4
IEC International Electrotechnical Commission. 3
IED An Intelligent Electronic Device is a device incorporating one or more processors with the capability to
execute application functions, store data locally in a memory and exchange data with other IEDs (sources
or sinks) over a digital link. 1, 3, 4, 8, 10, 37
MMS Manufacturing Message Specification. 1, 4
MSC Mechanically Switched Capacitor. 22
MSR Mechanically Switched Reactor.. 22
POD Power Oscillation Damping. 22, 31
SAS Substation Automation System, the computer based control, protection, monitoring, operation and remote communication system of a substation. 1
SCADA Supervisory Control And Data Acquisition. 2–4, 37, 38
SMV Sampled Measured Values. 1
SSR Subsynchronous resonance are torsional interactions of the rotor shaft of turbine-generators together
with the electrical transmission system that may fatigue or damage of the rotor shaft. 14, 27
STATCOM static synchronous compensator. 12, 20, 22, 50
SVC Static VAr Compensator. 12, 20, 22, 25, 28, 50
TCR Thyristor Controlled Reactor. 39, 41
TSC Thyristor Switched Capacitor. 39, 41
TSR Thyristor Switched Reactor. 39, 41
UCA Utility Communication Architecture. 3, 4
VAR Acronym for reactive power, Volt-Ampere-Reactive, see var. 12
var The unit (volt-ampere reactive) express reactive power of an AC electric power system. 22, 43
VSC Voltage Source Converter. 13, 25, 34, 39, 48
VT Voltage transformers are a parallel connected type of instrument transformer.. 4, 7, 37, 38
53
Appendix A
Svenska Kraftnäts Kraftsystemkarta
The transmission map of Sweden is included to show an example of a transmission net where large FACTS
devices are used to stabilise and improve transmission capacity. For instance, on the map one can find the long
400 kV lines stretching from north to south of Sweden. Without the series compensation it can be estimated
that Sweden would at least need four more lines.
54
KRAFTSYSTEMET 2014
N
Det svenska stamnätet omfattar kraft ledningar
för 400 och 220 kV med ställverk, transformatorstationer m.m. samt utlandsförbindelser för
växel- och likström.
OMFATTNING 2014
LUFTLEDNING
400 kV växelström
10 800 km
8 km
220 kV växelström
3 550 km
29 km
100 km
660 km
Högspänd likström (HVDC)
KABEL
Narvik
Ofoten
400 kV ledning
275 kV ledning
220 kV ledning
Rovaniemi
HVDC (likström)
Samkörningsförbindelse för
lägre spänning än 220 kV
Planerad/under byggnad
Røssåga
Vattenkraftstation
Kemi
SVERIGE
Värmekraftstation
Luleå
Vindkraftpark
Uleåborg
Transf./kopplingsstation
Planerad/under byggnad
Tunnsjødal
FINLAND
Sundsvall
NORGE
0k
(220 kV
)
(22
Vasa
Nea
V)
Umeå
Trondheim
Tammerfors
Olkiluoto
Rjukan
Bergen
Forsmark
Oslo
Viborg
Loviisa
Åbo
Helsingfors
Enköping
Tallin
Hasle
Stavanger
Rauma
Stockholm
(300 kV
)
ESTLAND
Kristiansand
Norrköping
Göteborg
Riga
Oskarshamn
LETTLAND
Ringhals
DANMARK
Karlshamn
Klaipeda
Malmö
Köpenhamn
Kass
Flensburg
Kiel
Lübeck
LITAUEN
Vilnius
Slupsk
Rostock
Eemshaven
0
100
200 km
Figure A.1: The nordic transmission line grid system. The right to the picture belongs to SVK.
55
Appendix B
Single Line Digram Series Capacitor, one
segment
Figure B.1: Single Line Diagram of a one segment Series Capacitor.
56
Appendix C
Single Line Digram SVC
Figure C.1: Single Line Diagram of a SVC with 2 TCR and 2 TSC branches.
57
Figure C.3: Example Single Line Diagram of a Thyristor Controlled Reactor
Figure C.2: Example Single Line Diagram of a Thyristor Switched Capacitor.
58
Appendix D
Introduction to control system for FACTS
controllers
D.1
Control system for communication, system interaction, protection
and control of power electronics
A FACTS device is controlled by control system. This control system consist of several different parts, for instance valve control that handles the very fast control of the power electronics, cooling control that controls the
valve cooling system and main control where control strategies or control modes is implemented. Additionally
there is protection control that protects the high voltage equipment from external and internal faults.
59
Communication levels for a FACTS controller
Function
Phase
10,7
Stattion
EMS/NCC/etc
Station HMI
SCADA Gateway
Switch
1
3,6,9
Bay
Local HMI
Control A
Control B
Protection
4,5
System bus
Process
4,5
VCU
+
+
VSC1
VSC2
TSC
Figure D.1: Communication structure of a shunt connected FACTS device.
60
Appendix E
Published parts of IEC 61850
Table E.1: A list of published parts of the standard and the current edition w publication year
Part
IEC 61850-1
IEC 61850-2
IEC 61850-3
IEC 61850-4
IEC 61850-5
IEC 61850-6
IEC 61850-7
IEC 61850-7-1
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-4
IEC 61850-7-410
IEC 61850-7-420
IEC 61850-7-510
IEC 61850-8
IEC 61850-8-1
IEC 61850-9
IEC 61850-9-1
IEC 61850-9-2
IEC 61850-10
Description
Introduction and overview
Glossary
General requirements
System and project management
Communication requirements for functions and device models
Configuration language for communication in electrical substations related to IEDs
Basic communication structure for substation and feeder
equipment
Principles and models
Abstract communication service interface (ACSI)
Common Data Classes
Compatible logical node classes and data classes
Hydro power plant
DER
Hydro power
Specific communication service mapping (SCSM)
Mappings to MMS (ISO/IEC9506-1 and ISO/IEC
9506-2)
Specific communication service mapping (SCSM)
Sampled values over serial unidirectional multidrop point to point link
Sampled values over ISO/IEC 8802-3
Conformance testing
61
Edition
2
Year
2013-03
2
2
2013-12
2011-4
2
2009-12
2
2
2
2
2
2011-07
2010
2010
2010
2012
1
2
2011-06
2
2011-09
Appendix F
Basic Types defined in IEC 61850-7-2
62
Table F.1: The Basic Types as defined in IEC 61850 Part 7-2, Table 2[WG110a]
Name
BOOLEAN
Value range
INT8
-128 to 127
INT16
-32 768 to 32 767
INT32
INT64
INT8U
-2 147 483 648 to 2 147 483
647
−263 to (263 ) − 1
Unsigned integer, 0 to 255
INT16U
Unsigned integer, 0 to 65 535
INT24U
Unsigned integer, 0 to 16 777
215
Unsigned integer, 0 to 4 294
967 295
Range of values and precision as specified by IEEE
754 single-precision floating
point
Ordered set of values, defined where type is used.
Values shall be assigned in
the SCSMs.
Ordered set of values, defined where type is used.
Values shall be assigned in
the SCSMs.
Max. length shall be defined
where type is used
INT32U
FLOAT32
ENUMERATED
CODED ENUM
OCTET STRING
Remark
0,1 (false, true)
VISIBLE STRING
Max. length shall be defined
where type is used
UNICODE STRING
Unicode coding is defined
in the SCSM. Max. length
shall be defined where type
is used
A currency identification
code based on ISO 4217
3-character currency code.
The concrete coding shall be
defined by the SCSMs.
Currency
63
Only used for TimeStamp
type
Used by
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
Custom extensions are allowed
IEC 61850-7-3
IEC 61850-7-2
Custom extensions shall not
be allowed. Type shall be
mapped to an efficient encoding in a SCSM
The NULL OCTET STRING
is implemented by an empty
OCTET STRING
The NULL VISIBLE STRING
is implemented by an empty
VISIBLE STRING
The
NULL
UNICODE
STRING is implemented
by an empty UNICODE
STRING
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-2
IEC 61850-7-3
IEC 61850-7-3
Figure F.1: Interface diagram of types defined in IEC 61850-7-2. Figure is part of IEC standard.
64
Appendix G
Proposed instantiation
This chapter describes an example implementation on logical devices and instances of logical nodes for the
use case used in the report. It uses the top-down communication diagram shown in earlier chapter 4.1
G.1
Nomenclature and structure set by the IEC 61850
The nomenclature used in this report is set by Part 7-2.
• LDName ≤ 64 characters
• LNName = [LN-Prefix] LN class name [LN-Instance-ID] where
LN-Prefix is m characters,
LN class name is 4 characters,
LN-Instance-ID is n numeric characters, and
m+n =7
• DataObjectClassName ≤ 10 characters, no DataObjectClassName shall end with a numeric character
• DataObjectName = DataObjectClassName[Data-Instance-ID]
• Data-Instance-ID = n numeric characters, optional; n shall be equal for all instances of the same data
class
• FCD ≤ 61 characters including all separators.
• FCDA ≤ 61 characters including all separators.
• DataSetName ≤ 52 characters.
• CBName = [CB-Prefix] CB class name [CB-Instance-ID]
– CB-Prefix = m characters (application specific)
– CB class name = 4 characters (as defined in IEC 61850-7-2)
– CB-Instance-ID = n numeric characters (application specific)
– m + n ≤ 7 characters
65
G.2
Single Line Diagram items used in use case and example implementation
The included table lists the SLD items modelled in the use case example.
Table G.1: SLD items modelled in example
Item designation
<=CLIENT.E1=WA1
<=CLIENT.E1=WA1=Q1
<=CLIENT.E1=WA1=Q2
<=CLIENT.E1=WA1=Q3
E1=SVC-BA1
E1=SVC-T1
E1=WA=MSC11
E1=WA=MSR11
E1=SVC=J1
E1=SVC=J1=WA1
E1=SVC=J1=Q1
E1=SVC=J1=Q2
E1=SVC=J1=Q3
E1=SVC=TCR11
E1=SVC=TCR11-TBC1
E1=SVC=TCR11-QT1
E1=SVC=TSC11
E1=SVC=TSC11-BC1
E1=SVC=TSC11-QT1
E1=SVC=CA11
G.3
Type
Bus bar
Disconnector
Disconnector
Disconnector
Voltage Transformer (VT)
Power Transformer
Mechanically Switched Capacitor Bank (MSC)
Mechanically Switched Reactor Bank (MSR)
SVC Busbar
Breaker
Breaker
Disconnector
SVC TCR Branch
TCR CT
TCR Valve
SVC TSC Branch
TSC CT
TSC Valve
Harmonic Filter
Proposed designation in IEC 61850
E1$WA$Q1
E1$WA$Q2
E1$WA$Q3
E1$SVC$T1
E1$WA$MSC11
E1$WA$MSR11
E1$SVC$J1$Q1
E1$SVC$J1$Q2
E1$SVC$J1$Q3
E1$SVC$TCR11
E1$SVC$TCR11$Q1
E1$SVC$TCR11$QT1
E1$SVC$TSC11
E1$SVC$TSC11$Q1
E1$SVC$TSC11$QT1
E1$SVC$CA11
Overview of IEDs, Logical Devices and Logical Nodes
The UML Deployment drawings describe the Substation overview of the SVC use case (Figure G.1), logical
devices of one of the control IEDs (Figure G.2) and the logical nodes of the same IED (Figure G.3). The engineering process and SCL-file flow is also shown in the two first figures.
66
Figure G.1: Overview of IEDs of the use case used in this report.
67
Figure G.2: Overview of Logical Devices of one IED in the use case.
68
Figure G.3: Overview Substation view of FACTS Controller.
69
Appendix H
Suggestions for standard updates
I’ve collected input for the standard committee work in this chapter. One could discuss if the addition of new
CDCs and LN should be added to main part of the standard (Part 7-1 to 7-4) or to a new part as for Hydro
(Part 7-410) and DER (Part 7-420). My choice would be to at least add new items that are of interest for all
other domains to the main parts, and where I suggest updates to exiting parts they should be added to the
parts where the original items are defined. New items that are not of interest to other domains could be added
as a separate part of the standard where a grouping with the scope of the task force 90-14 of WG10 probably is
relevant.
New Common Data Class In Section 7.3.2 the defined CDC VST should be added to Part 7-3 as the type could
be relevant to at least 7-420. Additionally the new enumerations needed for the logical nodes should be
added, all new CDCs are shown in Figure H.3 on page 72.
Data attribute
Name
VlvVal
NumUnt
NumStack
NumUntStack
maxUnt
New logical nodes
standard.
LN Name
CPEM
ARPC
APOD
CJCL
PRCC
PTRV
ZHAF
ZVSC
XFPD
Type
FC
TrgOp
ARRAY
of
0
maxUnt-1
OF
CODED ENSPEUnitStatus
INT16U
INT16U
INT16U
INT16U
ST
dchg
Value
M/O/C
M
1 < NumPts ≤ maxUnt
≥1
≥1
CF
CF
CF
CF
M
M
M
M
In the chapters 6 and 7 new logical nodes are described. The need to be added to the
Description
Control of Power Electrical Machine
Reactive Power Control
Power Oscillation Damping Control
Control of parallel FACTS Controllers
Current Protection of Thyristor Controlled Reactive Component
Voltage Protection of Thyristor Controlled Reactive Component
Harmonic Filter
Voltage Source Converter, reactive
component
Fast Protective Device
Defined in table
6.2
6.4
6.5
6.6
6.7
Page reference
29
33
35
35
35
6.8
35
7.7
-
43
44
7.8
45
Changed logical nodes Additional data objects should be added to the logical nodes below
LN Name
AVCO
ZTCR
Description
Voltage Control
Thyristor Controlled Reactive Component
Defined in table
6.3
7.6
Page reference
32
42
Part 5 Chapter 5.3 Addition of application example for FACTS. The application examples listed today are
”Substation to substation”, ”Substation to Network Control”, Wind, Hydro and DER.
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UML-model The abstract data types and logical nodes described in the UML implementation needs to be
added to the UML-model.
Figure H.1: Overview of additions to IEC 61850 presented in this report.
Figure H.2: Overview of LN additions to IEC 61850 presented in this report.
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Figure H.3: UML representation of new CDCs presented in this report. Same as Figure 6.3
72