Download Wind Power Facility Guide to the Technical Requirements Revision 0 November 30, 2004

Wind Power Facility
Guide to the Technical Requirements
Revision 0
November 30, 2004
November 30, 2004
Page 1 of 20
Technical Guide to the Wind Power Facility Technical Requirements
Preface
This document (“Guide”) is intended to provide wind power facility developers with assistance
in the application of the Alberta Electric System Operator’s Wind Power Facility Technical
Requirements (”WPFTR”) to their specific project applications.
The WPFTR can be found on the AESO website (www.aeso.ca).
In the event of any
inconsistency between the Guide and the Technical Requirements the latter prevails.
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Change History
Date
Version
Detail
Changed by
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TABLE OF CONTENTS
PREFACE.................................................................................................................................2
CHANGE HISTORY...............................................................................................................3
TABLE OF CONTENTS ........................................................................................................4
LIST OF FIGURES .................................................................................................................5
1.0
INTRODUCTION..................................................................................................6
2.0
OBJECTIVE ..........................................................................................................6
3.0
SCOPE ....................................................................................................................6
4.0
WIND POWER FACILITY DESCRIPTION AND DEFINITIONS................6
5.0
TECHNICAL REQUIREMENTS FOR WIND POWER FACILITIES .........6
5.1
Wind Power Facility Aggregated MW Capacity ......................................................................7
5.2
Voltage Ride Through Requirements ........................................................................................7
5.3
Voltage Regulation/Reactive Power Requirements ..................................................................9
5.4
Stability Control Requirements ...............................................................................................17
5.5
Operating Voltage Requirements.............................................................................................17
5.6
Off Nominal Frequency Requirements....................................................................................18
5.7
Supplemental Over Frequency Control Requirements..........................................................18
5.8
Wind Power Facility Disconnection .........................................................................................18
5.9
WPF Connection Requirements During Constrained Operating Conditions......................18
5.10
Protection Requirements ..........................................................................................................18
5.11
Power Quality ............................................................................................................................18
5.12
Grounding ..................................................................................................................................18
5.13
Lightning (Surge) Protection....................................................................................................19
5.14
Clearances and Access ..............................................................................................................19
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5.15
Interrupting and Isolation Devices ..........................................................................................19
5.16
Special Interconnection Protections.........................................................................................19
5.17
Revenue Metering......................................................................................................................19
5.18
Supervisory, Control and Data Acquisition (SCADA)...........................................................19
6.0
MONITORING REQUIREMENTS ..................................................................19
7.0
MODELLING AND VALIDATION..................................................................19
8.0
TESTING..............................................................................................................20
LIST OF FIGURES
Figure 5.1 - VRT Requirements for Low Voltage Conditions .................................................................................9
Figure 5.2 – Example Reactive Power Ramp with WTG’s ....................................................................................10
Figure 5.3 – Example Reactive Power Ramp with fixed and variable reactive power devices...........................11
Figure 5.4 – Example where reactive current compensation would be required.................................................13
Figure 5.5 –Example of a VRS response to a system voltage step .........................................................................14
Figure 5.6 - Voltage regulation provided at the WTGs ..........................................................................................14
Figure 5.7 - Voltage regulation on a single collector bus........................................................................................15
Figure 5.8 - Voltage regulation on a multiple collector bus injection at collector bus.........................................15
Figure 5.9 - Voltage regulation on a multiple collector bus injection at the transmission system bus ...............16
Figure 5.10 - Shared voltage regulation for multiple WPFs at the same transmission system bus ....................17
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1.0
INTRODUCTION
Guidance Note on Refurbishment or Replacement:
There are some industry practices on bringing facilities up to compliance with
current standards. For example, WECC has policy affecting excitation systems at
existing synchronous generating facilities.1 Key equipment at a WPF would
include replacement of generators, converters, reactive power devices, and
voltage regulation systems to name a few. It is also important to acknowledge
that a WPF has many turbines, and it may take several years to replace or
refurbish an entire WPF. A WPF could transition over time to fully comply with
the WPFTR.
Guidance Note of TFO Requirements:
The WPFTR is one of many requirements that effect WPF owners.
Transmission Facility Owners (TFOs) will also have technical requirements such
as protection coordination, equipment protection and SCADA2 that would be
applicable to WPFs.
2.0
OBJECTIVE
No guidance notes at this time.
3.0
SCOPE
No guidance notes at this time.
4.0
WIND POWER FACILITY DESCRIPTION AND DEFINITIONS
No guidance notes at this time.
5.0
TECHNICAL REQUIREMENTS FOR WIND POWER FACILITIES
The overall principle of the WPFTRs is to ensure that WPFs contribute to system
reliability. The NERC/WECC planning standards have an introductory section on
Generator Controls requirements. The AESO, in the development of the WPFTR, used
the NERC/WECC requirements, concepts and principles. Below is an excerpt from the
NERC/WECC planning standard for reader reference.
1
2
www.wecc.biz
Supervisory Control and Data Acquisition (SCADA)
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5.1
Wind Power Facility Aggregated MW Capacity
Guidance Note on WPF Aggregated MW Capacity:
The WPF Aggregated MW Capacity is determined at the Collector Bus(es).
The MW capability including real-power losses to the Collector Bus(es) should
be considered in the determination of WPF Aggregated MW Capacity . The
WPF Aggregated MW Capacity would also be based on the rated voltage of the
Collector Bus(es).
5.2
Voltage Ride Through Requirements
Guidance Note on VRT:
WPF owners will be required to provide the AESO with the over voltage tripping
characteristics for each type of WTG used at the WPF.
Guidance Note on Marginal Compliance for VRT:
The AESO has implemented VRT requirements to mitigate tripping of multiple
WPFs as identified in the ABB study.3 VRT is specified at the rated voltage for
3
Wind Power Study - Full Report found on the AESO website www.aeso.ca
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Technical Guide to the Wind Power Facility Technical Requirements
the Point of Connection. The AESO will provide the rated voltage of the Point
of Connection to the WPF owner.
Until January 1, 2006, a WPF with marginal VRT specifications that does not
meet the AESO VRT requirements are subject to review and approval by the
AESO before an application for connection can be submitted to the Alberta
Energy Utilities Board (AEUB).
The AESO would consider the following for example:
•
A WPF must have VRT down to 15% of the rated voltage at the Point of
Connection.
•
A WPF must have continuous operation at 90% of the rated voltage at the
Point of Connection.
•
A WPF may have marginal compliance to a variance in the 0.625 seconds
requirement at 15% Point of Connection voltage.
•
A WPF may have marginal compliance to a variance along the curve
between 0.625 seconds and 3 seconds of the AESO VRT requirements.
Figure 5.1 below shows the AESO proposed VRT curve in a first draft of the
WPFTR and the AESO final VRT curve in the WPFTR. The figure shows an
area where marginal VRT would be considered acceptable by the AESO.
Also, a marginally compliant WPF may consider the use of dynamic reactive
power control on the collector system or WTGs to improve VRT capability. A
WPF that is not compliant to the AESO VRT requirements will be required to
conduct technical studies demonstrating the length of time a WPF can ride
through voltage at the Point of Connection for the following voltage levels:
•
Time (seconds) that the WPF can ride through at 15% Point of
Connection voltage.
•
Time (seconds) that the WPF can ride through at 50% Point of
Connection voltage.
•
Time (seconds) that the WPF can ride through at 75% Point of
Connection voltage.
Any WPF that is approved by the AESO with marginal VRT would not be
subject to retroactive compliance, but would be subject to conform to compliance
based on replacement or refurbishment requirements that would impact all WPFs.
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Technical Guide to the Wind Power Facility Technical Requirements
Low Voltage Ride Through Requirements
Per Unit Voltage at Point of
Connection
1.2
1
0.8
0.6
The AESO would give consideration
for a WPF that falls short of the
WPFTR but would have met the
AESO proposed VRT in draft 1 of
the WPF standard process.
0.4
0.2
0
-2
0
2
4
6
8
10
12
14
Time (Seconds)
WPFTR
AESO Proposal (Draft 1)
Figure 5.1 - VRT Requirements for Low Voltage Conditions
5.3
Voltage Regulation/Reactive Power Requirements
The AESO standard has been developed to satisfy voltage regulation and reactive power
requirements while considering the unique characteristics of WPFs. Below is an excerpt
from the NERC/WECC Planning Standards for reader reference.
Guidance Note on the Requirements of the WPF Operator:
Section 5.3 and section 5.9 of the WPFTR state a requirement for a WPF
Operator. The AESO System Controller will require names and contact
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Technical Guide to the Wind Power Facility Technical Requirements
information for the WPF Operator. The WPF Operator will also be expected to
comply with requirements specified in the AESO Operating Policies and
Procedures.
Guidance Note on Reactive Power Requirements:
The reactive power requirements in the WPFTR provide flexibility for many
types of technologies at a WPF. The intent is that a WPF can ramp the reactive
power from -0.95 PF (power factor) to +0.90 PF at the Collector Bus(es) in a
smooth continuous fashion. Figure 5.2 below shows an example of a reactive
power ramp from a 60 MW WPF using WTGs to ramp throughout the reactive
power range.
Example Reactive Power at the Collector Bus for a 60 MW WPF
ramped from -0.95 PF to +0.90 over time
Reactive Power (+ is Out)
40
30
20
10
0
-10
-20
-30
-40
Time -->
Reactive Power Generated from WTGs
Figure 5.2 – Example Reactive Power Ramp with WTG’s
Figure 5.3 shows an example of a more complicated WPF that absorbs reactive power
with the WTGs, and has a -8 to +8 MVAr static var device in combination with three 13
MVAr capacitor banks switched as required. The combination of reactive power
produces a net WPF reactive power that continuously ramps from -0.95 PF to 0.90 PF.
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Reactive POwer (+ is Out)
Example Reactive Power at the Collector Bus for a 60 MW WPF ramped from -0.95
PF to +0.90 over time
40
30
20
10
0
-10
-20
-30
-40
MVArs absorbed by the
WTGs
MVAr (producing and absorbing)
from a Static Var Device
3 - 13 MVAr capacitor banks
switched by the VRS
Net Reactive Power from all Devices
Time -->
Fixed Static Reactive Power (WTG Offset)
Dynamic Vars (Continuous Capability Only)
Switched Shunt Reactive Power
Figure 5.3 – Example Reactive Power Ramp with fixed and variable reactive power
devices
The WPFTR specifies reactive power at the Maximum Aggregate MW Output of the
WPF. The intent of the reactive power requirement is such that the WPF will provide the
maximum amount of reactive power available when required to maintain voltage
regardless of MW conditions. The standard recognizes that reactive power capability of
WPFs may decrease at low MW output, however the WPF must make available all
reactive power capability. There cannot be controls withholding reactive capability. For
example, if the MW output of the WPF were to drop due a small change in wind, the
expectation would be that this does not equate to an automatic drop in reactive power.
The following are two examples for reactive power requirements.
Example 1:
A 60 MW WPF uses WTGs with +.9 to -.9 PF turbines where all reactive power is
continuous and dynamically responding. The turbine step up transformers and collector
network absorb 5 MVArs. The turbine capability at the Collector Bus would be +24
MVArs (+29-5) to -34 MVArs (-29-5). The WPF would add a 5 MVAr capacitor bank to
the collector system that would change the reactive power at the collector bus to +29
MVArs (+24 +5) and -30 MVars (-35+5). The WPF would provide +0.9 PF to -0.95 PF
at the Collector Bus as required in the WPFTR.
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Example 2:
A 60 MW WPF requires a capability of producing +29 MVArs to reach +0.9 PF and a
capability of absorbing -20 MVArs to achieve –0.95 PF. The WPF alone draws a fixed 12 MVArs to operate due to transformers, lines and the WTGs.
In order to meet the dynamic reactive power capability, the WPF needs to be able to
produce +20 MVArs and absorb -10.5 MVArs of short term reactive power. To reach
these short term amounts of +20 and –10.5 MVArs, a WPF may use a dynamic VAr
element that comes with ± 8 MVArs of continuous reactive power.
It is this ±8 MVArs that can be used to reach the capability of +0.9 PF and –0.95 PF. The
addition of the –12 MVAr fixed draw from the WPF with the –8 MVArs of continuous
reactive power results in the necessary -20 MVArs to reach -0.95 PF. Conversely, the
addition of the –12 MVAr fixed draw from the WPF with the +8 MVArs of continuous
reactive power results in a need of only 33 MVArs of additional capability to reach +0.9
PF.
Guidance Note on the Voltage Regulation System (VRS):
Voltage regulation at a WPF results when the WPF voltage control system:
•
measures the appropriate voltage at either the Collector Bus or Point of
Connection,
•
compares the voltage to a voltage set-point,
•
processes the error signal via control parameters such as proportional,
derivative and integral terms and changes the reactive power of the WPF
to correct the voltage.
A Typical industry standard, and one that the AESO uses, is where voltage is
regulated within +/- 0.5% of the voltage set point. Most conventional generator
voltage regulators can achieve +/- 0.5% through a combination of steady-state
Droop, gains and reactive current compensation. Typical voltage regulation gains
are between 100 to 200 p.u. Some newer voltage regulation controls may use
integrating type control parameters which would be interpreted as a 0% Droop
behavior.
The intent of WPF voltage regulation is to be reasonably comparable to
synchronous generators to ensure coordinated control behavior between all types
of generating facilities.
Guidance Note on Reactive Current Compensation 5.3.4.(g):
The AESO has also indicated that reactive current compensation may be required
in the VRS. Reactive Current Compensation (RCC) is a control system method to
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measure reactive current and modify the measured voltage signal. Many
synchronous generators may use RCC to make the virtual control point appear to
be in the middle of the transmission system step-up transformer.
An example of RCC requirements is shown in figure 5.4 where two WPFs are
configured such that the measured voltage by the Voltage Regulation Systems is
at the same transmission system point. In this example RCC will be required at
both WPFs.
WTGs
WTGs
138kV
WTGs
WTGs
WTGs
WTGs
WTGs
WTGs
Reactive
Power
Injection
External Voltage Regulation /
Reactive Power System
Reactive
Power
Injection
RCC
Voltage Sensing
Voltage Sensing
WIND POWER FACILITY 1
RCC
External Voltage Regulation /
Reactive Power System
WIND POWER FACILITY 2
AIES
Figure 5.4 – Example where reactive current compensation would be required
Guidance Note on Response time 5.3.4 (i):
The intent of the ‘no later than 1.0 second’ is to ensure reasonable response time
to co-ordinate voltage regulation with other generation facilities. The intent of the
‘no sooner than 0.1 second’ is to prevent possible system instability that can result
under weak system conditions that can occur with transmission line outages.
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Figure 5.5 –Example of a VRS response to a system voltage step
Examples of Voltage Regulation Placement:
The following figures are simple examples to illustrate some of the many options a
WPF has for voltage regulation and reactive power.
WTGs
< 690v
25 - 35 kV
69 - 240kV
WTGs
Voltage
Regulation
System
WIND POWER FACILITY
Figure 5.6 - Voltage regulation provided at the WTGs
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< 690v
WTGs
25 - 35 kV
69 - 240kV
WTGs
External Voltage
Regulation / Reactive
Power System
WIND POWER FACILITY
Figure 5.7 - Voltage regulation on a single collector bus
WTGs
< 690v
25 - 35 kV
69 - 240kV
WTGs
Collector
Bus
WTGs
WTGs
Reactive Power
Injection
External Voltage
Regulation / Reactive
Power System
Voltage Sensing
WIND POWER FACILITY
Figure 5.8 - Voltage regulation on a multiple collector bus
injection at collector bus
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WTGs
< 690v
25 - 35 kV
69 - 240kV
WTGs
WTGs
WTGs
External Voltage
Regulation / Reactive
Power System
WIND POWER FACILITY
Figure 5.9 - Voltage regulation on a multiple collector
bus injection at the transmission system bus
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WTGs
< 690v
25 - 35 kV
69 - 240kV
WTGs
WIND POWER FACILITY 1
WTGs
WTGs
WIND POWER FACILITY 2
External Voltage
Regulation / Reactive
Power System
EXTERNAL VOLTAGE REGULATION /
REACTIVE POWER
Figure 5.10 - Shared voltage regulation for multiple
WPFs at the same transmission system bus
If the WPF owners are different in Figure 5.10 it would be assumed that all
arrangements are sorted out between the owners prior to seeking review and approval by
the AESO. The reactive power capability of the External Voltage Regulation / Reactive
Power will need to satisfy both WPFs in this example as determined at the Collector
Buses.
5.4
Stability Control Requirements
No guidance notes at this time.
5.5
Operating Voltage Requirements
Guidance Note of Operating Voltage Range:
The AESO will provide the developer with the voltage levels the WPF is
expected to operate to, which is different than Section 5.2 which describes the
voltage range that the WPF must be able to withstand.
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5.6
Off Nominal Frequency Requirements
The off-nominal frequency requirements are established by WECC. The AESO requires
compliance to these WECC requirements.
Guidance Note of Off Nominal Frequency Requirements:
A WPF that uses computer or Programmable Logic Controller (PLC) systems for
frequency relays are considered equivalent to microprocessor relays in the
standard.
5.7
Supplemental Over Frequency Control Requirements
No guidance notes at this time.
5.8
Wind Power Facility Disconnection
A WPF may be required by the AESO System Controller to electrically disconnect from
the ATS for reasons of reliability or safety. Examples include and are not limited to:
1) During system restoration (blackout),
2) Following an event resulting in severe imbalance of supply and demand within
the AIES,
3) Following events resulting in transmission system voltages outside of
acceptable limits, and
4) An overload condition on transmission facilities.
5.9
WPF Connection Requirements During Constrained Operating Conditions
Most of the time the AIES operates normally and with no constraints on WPFs. On
occasions, transmission outage(s) or abnormal operating conditions can occur that will
require electric disconnection or partial curtailment of a WPF. A WPF that cannot be
partially curtailed during times of constrained conditions will remain electrically
disconnected from the ATS until the constraining issue has been resolved.
5.10
Protection Requirements
No guidance notes at this time.
5.11
Power Quality
No guidance notes at this time.
5.12
Grounding
No guidance notes at this time.
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5.13
Lightning (Surge) Protection
No guidance notes at this time.
5.14
Clearances and Access
No guidance notes at this time.
5.15
Interrupting and Isolation Devices
No guidance notes at this time.
5.16
Special Interconnection Protections
No guidance notes at this time.
5.17
Revenue Metering
No guidance notes at this time.
5.18
Supervisory, Control and Data Acquisition (SCADA)
The AESO requires SCADA of WPFs and the basic requirements are identified in
AESO Operating Policy and Procedure (OPP) 003.1. Additional requirements for Wind
Speed and Wind Direction are required from a WPF. Wind speed and wind direction
should be taken at a point that reasonably represents what the turbines are exposed to
such as at the hub height on a WTG or a meteorological station at the WPF. The wind
speed and wind direction need to be 1-minute averaged data or faster.
6.0
MONITORING REQUIREMENTS
No guidance notes at this time.
7.0
MODELLING AND VALIDATION
Guidance Note on Provision of Modeling Information:
The AESO requires models and model data for studies used by the PSS/E4
program. It is preferred that the models are standard models provided with
PSS/E, however the AESO recognizes that WPF technology will change and in
order to facilitate new technology, user written models may be required. WPF
owners that provide user written models will be required to keep these models
current with future versions of the PSS/E program until such time that PSS/E has
implemented a standard model.
4
Shaw PTI
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Guidance Note on Provision of Validated Models:
The AESO will be using WTG and VRS models for studies therefore it is
important that the models are accurate and validated. The AESO requires a report
from the WPF owner that indicates the WTG and/or VRS models are validated.
These reports may often come from manufacturers, but in some cases the testing
and validation of the WTG and/or VRS model may be the responsibility of the
WPF owner. These models will be required by the AESO to conduct studies prior
to applying to the AEUB for approval to connect the WPF.
8.0
TESTING
Guidance Note on Testing:
During the application process to interconnect, the models and model data are
determined prior to the WPF being commissioned. Simple tests can be conducted
that demonstrate through validation that the WPF models used in studies
reasonably represent the measured behavior of the WPF. The AESO will require
WPFs to conduct field tests to demonstrate the performance and capability of the
WPF to the WPFTR.
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