Robert Yinger

Integration of distributed energy resources. The CERTS Microgrid Concept

LBNL-50829 Consortium for Electric Reliability Technology Solutions White Paper on Integration of Distributed Energy Resources The CERTS MicroGrid Concept Prepared for Transmission Reliability Program Office of Power Technologies Assistant Secretary for Energy Efficiency and Renewable Energy U . S . Department of Energy Energy Systems Integration Program Public Interest Energy Research California Energy Commission Prepared by Robert Lasseter, Abbas A k h i l , Chris Marnay, John Stephens, Jeff Dagle, Ross Guttromson, A . Sakis Meliopoulous, Robert Yinger, and Joe Eto A p r i l 2002 The work described in this report was coordinated by the Consortium for Electric Reliability Technology Solutions, and funded by the Assistant Secretary of Energy Efficiency and Renewable Energy, Office of Power Technologies of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098 and by the California Energy Commission, Public Interest Energy Research Program, under Work for Others Contract No. B G 99-39.

Results of residential air conditioner testing in WECC

This paper summarizes the key results of testing work performed by three organizations (EPRI, SCE, and BPA) on a total of twenty seven air conditioning units in order to better understand and thus characterize their behavior for power system simulations. The diversity of the tested air conditioner units included sizes (tonnage), compressor technology (reciprocating and scroll), type of refrigerant (R-22 and R-410A), efficiencies (between 10 and 13 SEER), and vintage (new and old). A common test plan was developed by the three organizations. The tests were then performed independently by each of the three organizations. The EPRI work was sponsored by APS and SRP. This effort was part of the current load modeling effort going on in WECC under the load modeling task force. The key findings of this work are presented here together with a description of the testing methodology. All three organizations found very similar results despite testing a variety of different sizes and manufacturer units. The key results presented are associated with the stalling behavior of the units at different outdoor temperatures, the behavior of thermal overload tripping, contactor dropout, and the behavior of the units in response to different emulated types of system events.

Islands in the Storm: Integrating Microgrids into the Larger Grid

Evening is falling and the skies darken. A storm has been brewing all day, and now it settles in. Rain begins to fall and the winds increase. This is the type of storm that promises to keep utility field crews up all night. As night progresses, the storm starts to cause damage to the electrical system with downed trees, lightning strikes, and flooding problems. Sections of the city begin to experience power outages, and from a nearby hill, one can see areas of darkness as lights flicker out. Crews are being dispatched to locate problems and start the repair process. This is the way the electrical system responds to major storms today. Steps are taken to restore service as quickly as possible, but some outages are inevitable. If we look at this storm and its effects from the vantage point of a time in the future when microgrids have been established throughout the electrical system, however, things will be very different. This article discusses some of the engineering issues associated with the integration of microgrids into the larger electrical grid. It does not attempt to address all of the issues associated with microgrids, nor does it represent Southern California Edisons position on the deployment or merits of microgrids. Much more work in this area is still needed.

Solar PV inverter testing for model validation

This paper will cover the solar PV inverter tests required for model development and validation including but not limited to voltage transients, frequency deviations, grid disconnection, short circuit, harmonics generation, and voltage oscillations. Additionally, it will cover the test results acquired from our tests of 3-phase 480VAC commercial solar PV inverters. Finally, it will cover proposed recommendations for solar PV inverter performance to accommodate high penetration of solar PV inverter generation.

Fault Induced Delayed Voltage Recovery (FIDVR) indicators

This paper presents Fault Induced Delayed Voltage Recovery (FIDVR) indicators observed before, during and after several events in Southern California. The purpose of this paper is to educate utilities, independent system operators (ISOs), generator owners, customers, equipment manufacturers, and other entities involved with the production, transmission, distribution, and consumption of electricity based on our observations from our own experiences and from our review of the experiences of others. We believe the information in this paper can be used by ISOs for real-time FIDVR identification so that appropriate measures are used to stabilize the system. The observations presented may also be useful to load equipment manufacturers when designing electrical equipment with the capability of riding through these events.

Three phase solar photovoltaic inverter testing

This paper will cover the solar photovoltaic (SPV) inverter tests required for model development and validation including but not limited to voltage transients, frequency deviations, grid disconnection, short circuit, harmonics generation, and voltage oscillations. It will cover the test results acquired from 3-phase 480VAC commercial SPV inverters tests.

FIDVR in distribution circuits

This paper presents Fault Induced Delayed Voltage Recovery (FIDVR) events captured in Southern California desert areas with residential distribution circuits. Southern California Edison (SCE) installed 22 power quality recorders in SCEs Valley Subtransmission network. These devices recorded both sinusoidal and rms data from events triggered by voltage excursions. The purpose of this project is to acquire FIDVR data to validate WECCs composite load model. This data will support the load composition analysis in the WECC composite load model as well. The sinusoidal data can be used to validate transient models of stalling residential air conditioners. This effort is part of an integrated program of FIDVR research sponsored by the U.S. Department of Energy to promote national awareness, improve understanding of potential grid impacts, and identify appropriate steps to ensure reliability of the power system. The key results presented are associated with the stalling behavior of the air conditioner units in SCEs Valley substation region.

Solar photovoltaic inverters transient over-voltages

This paper presents solar photovoltaic (SPV) inverters test results performed in Southern California Edisons (SCE) Distributed Energy Resources (DER) laboratory. The labs engineers tested a variety of commercial three-phase solar PV inverters from different manufacturers and began performing commissioning tests on commercial SPV installations interconnected directly on SCEs distribution circuits. The primary objective of these load rejection tests is to assess transient over-voltages (TOV) created when SPV inverters are disconnected from the grid and injecting electrical power to the grid (load rejection). The data acquired in this project will support the updates to existing standards. The key results presented are associated with TOV generated by SPV inverters during grid disconnection.

Evaluation of German residential solar PV inverters

This paper evaluates five different residential solar photovoltaic (SPV) inverters, designed to operate according to German standards, in different system conditions. The testing was performed in Southern California Edisons (SCE) DER Laboratory in Westminster California. The main purpose for testing these inverters is to explore features not currently available in inverters that follow USA standards. These features include: ability to adjust ramp-up power rates, low voltage ride through, adjustment of power factor (PF) based on real power output, provide or withdraw VARs during voltage deviations, ability to adjust output real power during over-frequencies, and ability to communicate. The detailed results here will provide input to national standards being developed for advanced features. The test data can be used for model development and validation to assess grid performance with high penetration of inverters with these characteristics. For the tests the inverter frequency was adjusted from 50 to 60 hertz (Hz) to more properly simulate the electrical grid in the USA. The inverters output voltage was 230 volts line-to-ground, reflecting the typical German residential voltage configuration. The inverters could not be adjusted to split-phase 240 volts line-to-line, the typical USA residential voltage configuration.

Self-healing circuits at Southern California Edison

Southern California Edison has been investigating and demonstrating self-healing distribution circuit technologies for many years. Initial work resulted in the installation of automated mid-point switches that sense loss of voltage on most urban distribution circuits. The next generation of this system was demonstrated on the Circuit of the Future. This system uses fault interrupting switches throughout the circuit that communicate with each other using fiber-optic cables. This arrangement allows the protection system to identify the faulted circuit section and isolate it before the substation breaker trips. The latest demonstration of self-healing circuits is being designed for implementation on the Irvine Smart Grid Demonstration project. This self-healing circuit variation places fault interrupting switches on the distribution circuit with communications being accomplished with low-latency radios. Again, the faulted section of the circuit is isolated before the substation breaker is tripped. Two radial circuits are also looped so that when the faulted section of the circuit is tripped, all other sections of the circuit stay energized.