REPORT
System Impact
Assessment Report
(Addendum)
CONNECTION ASSESSMENT &
APPROVAL PROCESS
First Addendum
CAA ID:
2011-448
Project:
Grand Valley Wind Farms-Phase III
Applicant: Grand Valley 2 Limited Partnership
Connections & Registration Department
Independent Electricity System Operator
Date:
November 3, 2015
Public
Document ID
CAA 2011-448
Document Name
System Impact Assessment Report (Addendum)
Issue
1.0
Reason for Issue
First Addendum
Effective Date
November 3, 2015
© 2000, Independent Electricity System Operator.
System Impact Assessment Report (Addendum)
Public
System Impact Assessment Report (Addendum)
Acknowledgement
The IESO wishes to acknowledge the assistance of Hydro One in completing this assessment.
Disclaimers
IESO
This report has been prepared solely for the purpose of assessing whether the connection applicant's
proposed connection with the IESO-controlled grid would have an adverse impact on the reliability of the
integrated power system and whether the IESO should issue a notice of conditional approval or
disapproval of the proposed connection under Chapter 4, section 6 of the Market Rules.
Conditional approval of the project is based on information provided to the IESO by the connection
applicant and Hydro One at the time the assessment was carried out. The IESO assumes no responsibility
for the accuracy or completeness of such information, including the results of studies carried out by
Hydro One at the request of the IESO. Furthermore, the conditional approval is subject to further
consideration due to changes to this information, or to additional information that may become available
after the conditional approval has been granted.
If the connection applicant has engaged a consultant to perform connection assessment studies, the
connection applicant acknowledges that the IESO will be relying on such studies in conducting its
assessment and that the IESO assumes no responsibility for the accuracy or completeness of such studies
including, without limitation, any changes to IESO base case models made by the consultant. The IESO
reserves the right to repeat any or all connection studies performed by the consultant if necessary to meet
IESO requirements.
Conditional approval of the proposed connection means that there are no significant reliability issues or
concerns that would prevent connection of the proposed project to the IESO-controlled grid. However, the
conditional approval does not ensure that a project will meet all connection requirements. In addition,
further issues or concerns may be identified by the transmitter(s) during the detailed design phase that
may require changes to equipment characteristics and/or configuration to ensure compliance with physical
or equipment limitations, or with the Transmission System Code, before connection can be made.
This report has not been prepared for any other purpose and should not be used or relied upon by any
person for another purpose. This report has been prepared solely for use by the connection applicant and
the IESO in accordance with Chapter 4, section 6 of the Market Rules. This report does not in any way
constitute an endorsement, agreement, consent or acknowledgment of any kind of the proposed
connection for the purposes of obtaining or administering a contract with the IESO for the procurement of
electricity supply, generation, demand response, conservation and demand management or ancillary
services.
The IESO assumes no responsibility to any third party for any use, which it makes of this report. Any
liability which the IESO may have to the connection applicant in respect of this report is governed by
Chapter 1, section 13 of the Market Rules. In the event that the IESO provides a draft of this report to the
connection applicant, the connection applicant must be aware that the IESO may revise drafts of this
report at any time in its sole discretion without notice to the connection applicant. Although the IESO will
use its best efforts to advise you of any such changes, it is the responsibility of the connection applicant to
ensure that the most recent version of this report is being used.
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CAA 2011-448
Hydro One
The results reported in this report are based on the information available to Hydro One, at the time of the
study, suitable for a System Impact Assessment of this connection proposal.
The short circuit and thermal loading levels have been computed based on the information available at the
time of the study. These levels may be higher or lower if the connection information changes as a result
of, but not limited to, subsequent design modifications or when more accurate test measurement data is
available.
This study does not assess the short circuit or thermal loading impact of the proposed facilities on load
and generation customers.
In this report, short circuit adequacy is assessed only for Hydro One circuit breakers. The short circuit
results are only for the purpose of assessing the capabilities of existing Hydro One circuit breakers and
identifying upgrades required to incorporate the proposed facilities. These results should not be used in
the design and engineering of any new or existing facilities. The necessary data will be provided by
Hydro One and discussed with any connection applicant upon request.
The ampacity ratings of Hydro One facilities are established based on assumptions used in Hydro One for
power system planning studies. The actual ampacity ratings during operations may be determined in realtime and are based on actual system conditions, including ambient temperature, wind speed and project
loading, and may be higher or lower than those stated in this study.
The additional facilities or upgrades which are required to incorporate the proposed facilities have been
identified to the extent permitted by a System Impact Assessment under the current IESO Connection
Assessment and Approval process. Additional project studies may be necessary to confirm
constructability and the time required for construction. Further studies at more advanced stages of the
project development may identify additional facilities that need to be provided or that require upgrading.
CAA 2011-448
First Addendum – November 3, 2015
System Impact Assessment Report (Addendum)
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Notification of Conditional Approval
Notification of Conditional Approval
Grand Valley 2 Limited Partnership (the “connection applicant”) is developing a new 40.06 MW wind
generation facility, Grand Valley Wind Farms - Phase III (the “project”), in Grand Valley, Ontario. The
project will be connected to the IESO-controlled grid via 230 kV circuit B4V, about 15 km from
Orangeville TS. The project has been awarded a Power Purchase Agreement under the Feed-In Tariff
(FIT) program with the formerly Ontario Power Authority (now IESO). The scheduled project in-service
date is Q4, 2015.
The System Impact Assessment (SIA) for the project (CAA ID 2011-448) was completed on February 3,
2012. Recently, the connection applicant has notified the IESO of the following changes to the project:

The type of wind turbine generator (WTG) has changed from Siemens SWT2.3 DD to Siemens
SWT3.2 DD.

The number of WTGs has reduced from eighteen to sixteen. 14 WTGs will be de-rated to 2.483
MW and 2 WTGs will be de-rated to 2.648 MW.

The number of 34.5 kV collector systems has reduced from three to two. Each collector will have
eight WTGs connected to it.

The under-load tap changer (ULTC) characteristics of the main step-up transformer changed from
± 6%, 28 steps to ± 23 kV, 32 steps.
This assessment concludes that subject to the requirements specified in this report and the original SIA
report, the proposed project changes is expected to have no material adverse impact on the reliability of
the integrated power system. It is recommended that a Notification of Conditional Approval for
Connection be re-issued for the project subject to implementation of the requirements outlined in this
report and the original SIA report.
IESO Requirements for Connection
Connection Applicant Requirements
Specific requirements:
(1) The project is required to have the capability to inject or withdraw reactive power continuously (i.e.
dynamically) at the connection point up to 33% of its rated active power at all levels of active power
output.
Based on the proposed project changes, reactive power compensation of 6.9 Mvar capacitive at 34.5
kV needs to be installed at the project’s 34.5 kV collector bus to satisfy the Market Rules
requirements for reactive power capability. The original SIA required the installation of 10.0 Mvar
capacitive at 34.5 kV, which is no longer required.
The connection applicant has an obligation to ensure that the project has the required reactive power
capabilities and to be able to confirm these capabilities during the commission tests.
This requirement supersedes the connection applicant’s specific requirement (2) in the Executive
Summary of the original SIA report.
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Data Verification
Public
1.
Data Verification
1.1
Connection Arrangement
System Impact Assessment Report (Addendum)
The updated connection arrangement is shown in Figure below.
Figure 1: Updated connection arrangement
1.2
Updated Transformer and Collector System Data
The updated parameters for the 230 kV transformer are listed as follows:
Table 1: Specifications of the 230 kV transformer
Continuous
10-Day
Transformation Rating (MVA)
LTR
(kV)
(ONAN/ONAF/
(MVA)
OFAF)
230/34.5
25/35/45
1
45
15-min
STR
(MVA)
1
45
Positive Sequence
Impedance (pu)
SB= 25 MVA
HX: 0.004+j0.08
Configuration
H
L
Yg
Delta
High Voltage ULTC
Tap Changer
230 ± 23 kV in 32
steps
(1) Assumed to be the same as the continuous rating for this assessment.
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Data Verification
The under-load tap changer (ULTC) characteristics of the main step-up transformer changed from ± 6%,
28 steps to ± 23 kV, 32 steps.
The updated parameters for equivalent 34.5/0.69 kV generator step-up transformers and 34.5 kV collector
systems are listed as follows:
Table 2: Specifications of the equivalent generator step-up transformers
Transformation
(kV)
Equivalent
Transformer
MVA
Positive Sequence
Impedance (pu)
SB= 23.2 MVA
34.5/0.69
23.2
HX: 0.006+j0.06
Configuration
H
L
Delta
Yg
Table 3: Specifications of equivalent collector systems
1.3
Collector
Number
of WTGs
Positive Sequence Impedance (pu)
R+jX, B; SB= 100 MVA
C1
8
0.0544+j 0.0437, 0.0192
C2
8
0.0594+j 0.1025, 0.022
Updated Voltage Ride-Through Capability
Table 4: WTG voltage ride-through capability
Voltage Range (pu)
Minimum time for WTGs to Remain Online (sec)
V<0.15
0.85
0.15<V<0.40
1.6
0.40<V<0.70
2.6
0.70<V<0.875
3
0.875<V<0.90
200
0.90<V< 1.10
No trip
1.10<V< 1.20
1.00
1.20<V< 1.30
0.15
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Data Verification
1.4
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System Impact Assessment Report (Addendum)
Updated Reactive Power Capability Curves
Figure 2: Reactive power limits curves for 2.483 MW and 2.648 MW WTGs at LV side of generator step-up
transformer.
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2.
Assessments
2.1
Study Assumptions
Assessments
In this assessment, a 2015 summer base case was used. The generation at Bruce GS A, Bruce GS B,
Ripley South CGS, and Underwood WGS were maximized and the generation in Toronto and the East
zones was dispatched down or off to increase Flow Away from the Bruce Complex plus wind (FABCW)
transmission interface to 6658 MW. The generation in West, Southwest and Niagara zones were
dispatched to set the flow on the Negative Buchanan Longwood Input (NBLIP) transmission interface at
1991 MW and Flow East to Toronto (FETT) transmission interface at 6724 MW.
2.2
Reactive Power Compensation
The Market Rules (MR) require that a generation facility injects or withdraws reactive power
continuously (i.e. dynamically) at its connection point up to 33% of its rated active power at all levels of
active power output except where a lesser continually available capability is permitted by the IESO. A
generating unit with a power factor range of 0.90 lagging and 0.95 leading at rated active power,
connected through an impedance between the generator and the connection point that is not greater than
13% based on rated apparent power, provides the required range of dynamic reactive power capability at
the connection point.
A dynamic reactive compensation device (e.g. STATCOM or SVC) is required for a generation facility
which employs generating unit(s) that cannot provide a reactive power range of 0.90 lagging power factor
and 0.95 leading power factor at rated active power.
A wind generation facility can compensate for reactive power losses in its collector systems by installing
static shunts (e.g. capacitors and reactors).
This section assesses whether the project meets the market rules requirements for reactive power
capabilities. If project does not meet requirements, the assessment proposes a solution for the project to
meet the reactive power capabilities by establishing the type and size(s) of the additional reactive power
compensation required. However, the connection applicant can deploy any other solutions which result in
its compliance with the requirements. The connection applicant shall be able to confirm required reactive
power capabilities during the commission tests.
It should be noted that this assessment uses the equivalent electrical models of the project (WTGs, unit
step-up transformer and collectors) that was provided by the connection applicant. This equivalent
representation of the project cannot accurately represent the voltage at each individual WTG. When
deployed, some WTGs may reach the limit of their terminal voltage before injecting or withdrawing their
maximum reactive power. The connection applicant should ensure, during the detailed design of the
project, that the WTGs are not limited in their capability to produce reactive power due to terminal
voltage limits or other project’s internal limitations. For example, the transformation ratio of the generator
step-up transformers can be set to offset the voltage profile along the collector, allowing all WTGs to
contribute to the reactive power production of the project in a shared amount.
Dynamic Reactive Power Capability
The following table summarizes the required level of dynamic reactive power and the project’s available
dynamic reactive power capability shown in Figure 2 for each WTG.
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Table 5: Dynamic reactive power: Requirement vs Project WTG capability
Active Power
C1: 20.194 MW
Requirement
C2: 19.864 MW
C1: 20.194 MW
Project WTG
capability
C2: 19.864 MW
Reactive Power Capability per WTG
Power
Factor
Qgen =20.194 × tan [cos-1 (0.9)]= 9.78 Mvar
0.9 lag
-1
0.95 lead
-1
0.9 lag
-1
Qabs =19.864 × tan [cos (0.95)]= 6.52 Mvar
0.95 lead
Qgen = 12.14 Mvar @ terminal voltage=1.05 pu
0.86 lag
Qabs = 6.88 Mvar @ terminal voltage=0.95 pu
0.95 lead
Qgen = 12.16 Mvar @ terminal voltage=1.05 pu
0.85 lag
Qabs = 7.92 Mvar @ terminal voltage=0.95 pu
0.93 lead
Qabs =20.194 × tan [cos (0.95)]= 6.64 Mvar
Qgen =19.864 × tan [cos (0.9)]= 9.62 Mvar
The project’s WTGs can deliver the required dynamic reactive power to each generator terminal at rated
active power and at rated voltage. Thus, there is no need for the connection applicant to install additional
dynamic reactive power compensation. Study results show that dynamic reactive power injection
requirements for both collector systems materialize when the voltage on the connection point drops below
235 kV.
Static Reactive Power Capability
In addition to any dynamic reactive power requirement identified in the previous section, the project has
to compensate for the reactive power losses within the facility, to ensure that it has the capability to inject
or withdraw reactive power up to 33% of its rated active power at the connection point. These losses can
be compensated by the installation of additional switchable static shunts.
As such, the project, based on its rated active power of 40.06 MW, must have a minimum capability of
supplying approximately +13.22 Mvar (capacitive) to -13.22 Mvar (inductive) at the connection point
for all active power outputs.
Load flow studies were performed to calculate the need for static shunts, using the equivalent models
detailed in section 1.2.
The reactive power capability in lagging power factor of the project was assessed under the following
assumptions:
 typical voltage of 243 kV at the connection point;
 maximum active power output from the equivalent WTG;
 maximum reactive power output (lagging power factor) from the equivalent WTG, unless limited
by the maximum acceptable WTG terminal voltage;
 maximum acceptable WTG voltage is 1.05 pu, as per WTG voltage capability;
 the main step-up transformer ULTC is available to adjust the LV voltage as close as possible to 1
pu.
The reactive power capability in leading power factor of the project was assessed under the following
assumptions:
 typical high voltage of 249 kV at the connection point;
 minimum (zero) active power output from the equivalent WTG;
 maximum reactive power consumption (leading power factor) from the equivalent WTG, unless
limited by the minimum acceptable WTG terminal voltage;
 minimum acceptable WTG voltage is 0.95 pu, as per WTG voltage capability;
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the main step-up transformer ULTC is available to adjust the LV voltage as close as possible to 1
pu.
The study results show that the project is deficient in supplying +2.32 Mvar (capacitive) at the
connection point because the reactive power output of the WTGs were limited by the WTG terminal
voltage reaching 1.05 pu. As a result, the connection applicant must install at least 6.9 Mvar of additional
capacitive reactive power compensation at the project’s 34.5 kV collector bus to satisfy the requirement.
The study results show that the project supplies -26.6 Mvar (inductive) at the connection point, which
satisfies the requirement.
Tap Line and Collector System Charging
During high or low wind conditions, the project’s WTGs may automatically disconnect themselves from
the IESO-controlled grid. This leaves the project’s tap line and collector system connected to the grid
providing charging reactive power to the grid. Simulation results show that under this situation, the
project will inject 4.1 Mvar of reactive power into the grid at the connection point, which may aggravate
high-voltage situations under some system conditions. The project must be capable of reducing the
reactive power injection at the connection point to zero at the request of the IESO. Should this situation
arise, the IESO will direct the project to reduce this injection. This may be obtained by installing at the
project a shunt reactor of appropriate size, enhancing the project’s WTGs so that they can provide
reactive power when there is no wind, or disconnecting manually the project’s collectors when in
operation. Shall the project fail to meet the IESO’s direction; the IESO reserves the right to ask the
connection applicant to disconnect the project from the IESO-controlled grid.
Static Shunt Reactive Power Switching
The Ontario Resource and Transmission Adequacy Criteria (ORTAC) requires the voltage change on a
single capacitor switching to be no more than 4% at any point in the IESO-controlled grid. A switching
study was carried out to investigate the effect of switching a 6.9 Mvar, single, shunt capacitor on the
voltage changes. The results showed that switching a 6.9 Mvar capacitor results in less than a 4% voltage
change at any point in the IESO-controlled grid.
2.3
Transient Stability Performance
With the new dynamic model provided for the project’s WTG, transient stability simulation were
performed to determine if the power system will be transiently stable with the incorporation of the project
for design fault conditions. Also, the line protections for 500 kV circuit B560V has been modified with
new clearing times shown in Table 6.
The transient responses in Figure 3 for the most severe contingency, an LLG fault on B560V+B561M at
Willow Creek junction (Bruce SPS not armed), show that the nearby synchronous generators remain
synchronized to the power system and the oscillations are sufficiently damped.
Table 6: The simulated contingency for transient stability analysis
Fault Clearing Time (ms)
Contingency
B560V+B561M
Location
Willow Creek
junction
First Addendum – November 3, 2015
Fault
Type
LLG
Local
Remote
B560V
B561M
B560V
B561M
70
66
70
100
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Reclosure
Time
10 sec (B560V)
15 sec (B561M)
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System Impact Assessment Report (Addendum)
Figure 3: Rotor angle transient responses following an LLG fault on B560V+B561M at Willow Creek
junction
2.4
Voltage Ride-Through Capability
The updated voltage ride-through (VRT) capability of the project’s WTGs is shown in Table 4. A VRT
analysis was performed to assess the changes at the WTG terminal voltage due to the proposed project
changes. Using the VRT settings in Table 4, the project was subjected to the contingency shown in Table
7. The result is shown in Figure 4.
Table 7: The simulated contingency for voltage ride-through capability
ID
SC1
Contingency
B5V+L5L9-BKF @
Orangeville
Location
Orangeville
230 kV
Fault
Type
3 phase*
Fault Clearing
Time (ms)
B5V@
Bruce
Orangeville
DL9, HL5
E9V
106
192
207
* Note that a 3 phase fault with a breaker failure has been simulated in place of a line to ground (LG) fault with a breaker failure,
as this represents a more conservative and more severe fault. If voltage ride through is adequate for a three phase fault, then
voltage ride through for a LG fault will also be adequate.
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Figure 4: WTG terminal bus voltage following a 3-phase fault on B5V at Orangeville 230 kV bus with delayed
clearing due to L5L9 breaker failure at Orangeville TS.
As shown in Figure 4, the WTG terminal voltage recovers within 0.9 –1.1 pu in less than 200 ms after the
fault inception. When compared to the VRT capability, the WTGs will be able to remain connected to the
grid for design system contingencies that do not remove the project by configuration.
When the project is incorporated into the IESO-controlled grid, if actual operation shows the project’s
WTGs trip for contingencies that do not remove the project by configuration, the IESO will require the
VRT capability be enhanced by the connection applicant to prevent such tripping.
As noted in the general requirements of the original SIA, the VRT capability must also be demonstrated
during commissioning by monitoring several variables under a set of IESO specified commissioning tests
and the results must be verifiable using a PSS/E model of the project’s WTGs.
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