Steven Robles

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 current contribution from single-phase PV inverters

A significant increase in photovoltaic (PV) system installations is expected to come on line in the near future and as the penetration level of PV increases, the effect of PV may no longer be considered minimal. One of the most important attributions of additional PV is what effect this may have on protection systems. Protection engineers design protection systems to safely eliminate faults from the electric power system. One of the new technologies recently introduced into the electric power system are distributed energy resources (DER). Currently, inverter-based DER contributes very little to the power balance on all but a few utility distribution systems. As DER become prevalent in the distribution system, equipment rating capability and coordination of protection systems merit a closer investigation. A collaborative research effort between the National Renewable Energy Laboratory (NREL) and Southern California Edison (SCE) involved laboratory short-circuit testing single-phase (240 VAC) residential type (between 1.5 and 7kW) inverters. This paper will reveal test results obtained from these short-circuit tests.

Evaluation of German 3-phase solar PV inverter

This paper provides the test results for a solar photovoltaic (SPV) inverter designed to operate according to German standards. The testing was performed in Southern California Edisons (SCE) Distributed Energy Resources (DER) Laboratory in Westminster, California. The primary reason for testing this inverter is to explore features not used in inverters must comply with U. S, standards. These features include the ability to: communicate, adjust ramp-up power rates, perform voltage ride-through, adjust power factor (PF) based on real power output, inject or absorb reactive power (vars) during voltage deviations, and reduce output real power during over-frequencies. The results detailed here provide information that can be used to develop national standards for advanced features. The test data can also be used for model development and validation to assess grid performance with a high penetration of inverters with these characteristics.

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.

VAr support from solar PV inverters

This paper provides an overview of the need and applications for solar photovoltaic (PV) inverters with Volt/VAr feature to provide grid support during steady state and/or system events. This paper will also provide test results from residential and commercial PV inverters designed to operate according to German standards, which now allows voltage support. The residential inverters output voltage was 230 volts line-to-ground and the commercial was 400 volts line-line, reflecting the typical German residential and commercial voltage configurations respectively. The inverters frequency was adjusted to 60 Hz in order to reflect American standard practices. The testing was performed in Southern California Edisons (SCE) Distributed Energy Resources (DER) Laboratory in Westminster, California. The primary reason for the testing is to explore features not presently required by U.S. standards. The results detailed here provide information that can be used to develop national standards for voltage regulation features on PV inverters.

Evaluation of a residential solar PV inverter with advanced features for the U.S. market

This paper provides an evaluation of a solar photovoltaic (SPV) inverter with advanced features manufactured for use in the United States. The testing was performed by Southern California Edisons (SCE) Distributed Energy Resources Laboratory in Westminster, California. The inverters advanced features include the ability to communicate, adjust ramp-up power rates, allow low voltage ride-through, adjust power factor (PF) based on real power output, reduce real power output during over-frequencies, provide/absorb vars to regulate voltage, and provide power during blackouts. The results detailed in this paper will provide much needed information for the development of national and state standards for inverters with 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. The test inverters output voltage is split-phase 240-volts line-to-line reflecting the typical American residential voltage configuration.