Protection Coordination
Analyzing and proposing protection schemes and settings
At a glance
Our solution
Siemens Power Technologies International
(Siemens PTI), the provider of network consulting, software solutions and T&D training within
Siemens Energy, analyzes protection systems
using state-of-the-art methods to optimize operation and eliminate weak points. With the aid
of system calculations based on national and
international standards, and system and protection simulations, we devise a protection system
that is:
Our team comprises highly skilled experts in all
aspects of system and machine protection, from
converter design and equipment protection to
coordination of low, medium, high and extrahigh voltage protection: We can advise and
offer you a comprehensive service in the wide
area of power system protection.
„ Selective,
When faults occur, they must be cleared as
quickly as possible in order to obtain a high
level of system availability with minimum failure
probability. There are a number of methods
available for analyzing the causes and the behavior of the network and the protection system:
„ System compliant, and
„ Technically and economically suited for the
customer’s requirements.
The challenge
An electrical power system is intended to operate in a safe manner at all times. However, no
matter how well designed, faults will always
occur on a power system. Faults are very special events in the life cycle of a public or industrial system, as they can greatly affect or restrict operation. They may also lead to severe
damages of installations and equipment, or may
cause personal injuries, including death. Therefore, the arrangement of an adequate protection
system is an indispensable and integral part of
power system design.
Application Examples
From a disturbance to an optimized system
„ Analysis of fault records and fault annunciations from protection relays, from substation
control and protection systems, and from
SCADA systems
„ Dynamic system and protection equipment
simulation
„ Weak point analysis and development of
countermeasures
„ Verification of the optimized system
30,0
27,5
25,0
22,5
20,0
17,5
X/Ohm(secondary)
15,0
12,5
10,0
7,5
5,0
2,5
0,0
-2,5
-5,0
-7,5
-10,0
-12,5
-15,0
-40
Figure 1: Lightning stroke to overhead line
Siemens PTI − Network Consulting
-30
-20
-10
0
R/Ohm(secondary)
10
Figure 2: Fault analysis -- Zone 1 trip of distance protection on remote-end due to wrong earth-fault compensation factor settings
From the primary system to the
protection equipment
From the protection equipment to a
coordinated system protection
The choice of suitable current and voltage transformers as connection links
between the primary and protection
systems depends on the steady-state
and transient phenomena and the technical requirements of the connected
equipment.
Selective system protection must take
into account the system structure, the
system elements, different switching
conditions and supplier and customer
requirements.
Siemens PTI offers the following services:
„ Classification according to national
and international standards
„ Dimensioning of instrument transformers to suit all common protection
equipment
„ Dimensioning of instrument transformers when the specifications of the primary system and protection equipment change.
carried out using software aided short
circuit and / or system stability calculations.
Siemens PTI offers the following services:
„ Design of protection systems
„ Selection of suitable relays and fuses
„ Relay consistent setting calculation
„ Coordination of all protection equipment.
The analysis is based on a comprehensive data collection in close cooperation
with the customer. Thereby, the system
structure, its elements and operational
conditions are collected.
Figure 6: SIGRADE grading path
E
L1
L3
L1'
L2
Circuit 1
L2'
L3'
Circuit 2
Figure 3: CTDim dynamic simulation
With our software program CTDim instrument transformers can be studied
and dimensioned. For more details
please refer to a separate fast facts
sheet from the Siemens PTI Software
Solutions portfolio.
Figure 4: Example of distance zone protection
settings
Figure 5: Short-circuit considerations on OHL
After data collection, instrument transformers are checked and / or newly dimensioned and selected, enabling
proper operation of corresponding relays. In parallel, an analysis of the protection system concepts is carried out,
considering the customer’s requirements, habits and state-of-the-art.
Based on all these aspects the optimum
protection scheme is devised which
provides to the customer the technically
and economically best solution. Selective protection coordination and relay
consistent setting calculations are then
Figure 7: SIGRADE grading diagram
Published by and copyright © 2009:
Siemens AG
Energy Sector
E D SE PTI
Freyeslebenstrasse 1
91058 Erlangen, Germany
Siemens Energy, Inc.
Power Distribution, T&D Service Solutions
Siemens Power Technologies International
400 State Street
PO Box 1058
Schenectady, NY 12301-1058
For more information, please contact
our Customer Support Center.
Phone: +49 180 524 70 00
Fax:
+49 180 524 24 71
(Charges depending on provider)
E-mail: support.energy@siemens.com
www.siemens.com/energy/power-technologies
Siemens Transmission and Distribution Ltd
PTI
Sir William Siemens House, Princess Road
Manchester, M20 2UR
United Kingdom
Power Distribution Division
Printed in Germany
Printed on elementary chlorine-free
bleached paper.
All rights reserved.
Trademarks mentioned in this document
are the property of Siemens AG, its affiliates,
or their respective owners.
Subject to change without prior notice.
The information in this document contains general
descriptions of the technical options available,
which may not apply in all cases.
The required technical options should therefore be
specified in the contract.
NC3010-EN-200905