Transcript Solar PV Inverters

Solar PV Inverters
Anuj Dixit
Planning Engineer
Resource Integration
RPG Meeting
August 17, 2012
Definition and Purpose
• Definition: Intermittent Renewable Resource (IRR)
- A Generation Resource that can only produce energy from variable
uncontrollable resources such as wind, solar or run-of-the-river
hydroelectricity.
• Purpose
- ERCOT is encountering some projects in which the inverter
designs limit the capability of the solar plant because all of the
protocol requirements were not considered in the design.
- So far, these limitations have been on reactive capability across
operating range.
November 14, 2011
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Outline
• Solar projects in ERCOT
• Example
• Modeling requirements
• Protocol requirements
• Summary
• Questions / Discussion
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Example - Reactive capability
Reactive curve for a sample inverter, 0.95 pf lead/lag requirement
0.900
P MW
0.800
0.750 MW
0.700
0.600
0.500
0.400
Operating Area
0.300
0.200
0.100
-0.400
-0.250
-0.200
-
0.000
0.000
0.200 0.250
0.400
MVAr
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Solar PV projects
• 506 MW solar projects in the Study Phase
• Majority of the projects are solar PV
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Modeling requirements – FIS perspective
• Steady state
– Active/Reactive Power Capability
– Voltage control settings
– Generator step up transformer
• Short circuit
– Equivalenced collector system model
• Dynamic
– Compatible PSS/E standard model or a user defined model
• PSCAD Model for SSCI Studies ?
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ERCOT Protocols and other binding documents
• Voltage ride through capability (Operating Guide 2.9.1)
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ERCOT Protocols and other binding documents
• Frequency Control (Protocol 8.5 Primary Frequency Response
Requirements and Monitoring)
- At all times an All-Inclusive Generation Resource is On-Line, its
Governor must remain in service and be allowed to respond to all
changes in system frequency except during startup, shutdown, or
testing. …All Generation Resources that have capacity available to
either increase output or decrease output in Real-Time must provide
Primary Frequency Response, which may make use of that
available capacity. Only Generation Resources providing Regulation
Up (Reg-Up), Regulation Down (Reg-Down), Responsive Reserve
(RRS), or Non-Spinning Reserve (Non-Spin) from On-Line
Resources, as specified in Section 8.1.1, QSE Ancillary Service
Performance Standards, shall be required to reserve capacity that
may also be used to provide Primary Frequency Response.
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ERCOT Protocols and other binding documents
• Voltage Control : Reactive Capability 0.95 lead lag capability
over the entire range (Protocol 3.15)
-Reactive Power Requirements: an over-excited (lagging) power factor
capability of 0.95 or less and an under-excited (leading) power factor capability
of 0.95 or less, both determined at the generating unit's maximum net power to
be supplied to the ERCOT Transmission Grid and at the transmission system
Voltage Profile established by ERCOT, and both measured at the POI.
– The Reactive Power requirements shall be available at all MW output
levels and may be met through a combination of the Generation Resource’s
Unit Reactive Limit (URL), which is the generating unit’s dynamic leading and
lagging operating capability, and/or dynamic VArcapable devices.
– Generation Entities may submit to ERCOT specific proposals to meet the
Reactive Power requirements established in paragraph (3) above by employing
a combination of the URL and added VArcapability, provided that the added
VArcapability shall be automatically switchable static and/or dynamic
VArdevices. ERCOT may, at its sole discretion, either approve or deny a
specific proposal, provided that in either case, ERCOT shall provide the
submitter an explanation of its decision.
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Summary
• Inverter selection must consider how the design will meet
ERCOT protocols and other binding document (grid code)
• Inverter characteristics may be improved with design
modifications (i.e. it may be possible that an inverter who’s
published specifications do not meet the ERCOT requirements
can be modified to meet these requirements)
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Questions ?
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