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Papers by Michael Coddington

Research paper thumbnail of Current Utility Screening Practices, Technical Tools, Impact Studies, and Mitigation Strategies for Interconnecting PV on the Electric Distribution Systems

Research paper thumbnail of Beta Test Plan for Advanced Inverters Interconnecting Distributed Resources with Electric Power Systems

Research paper thumbnail of National Renewable Energy Laboratory Golden, CO

National Renewable Energy Laboratory (formerly the Solar Energy Research Institute) 1617 Cole Bou... more National Renewable Energy Laboratory (formerly the Solar Energy Research Institute) 1617 Cole Boulevard Golden, Colorado 80401-3393 Operated by the Midwest Research Institute for the US Department of Energy under Contract No. DE-ACO2-83CH10093

Research paper thumbnail of Summary of Electric Distribution System Analyses with a focus on DERs

Research paper thumbnail of Field Guide for Testing Existing Photovoltaic Systems for Ground Faults and Installing Equipment to Mitigate Fire Hazards

Research paper thumbnail of IEEE 1547 Standards advancing grid modernization

2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC), 2015

Research paper thumbnail of Ultra-low viscosity epoxy sealer/healer

Research paper thumbnail of An Advanced Platform for Development and Evaluation of Grid Interconnection Systems Using Hardware-in-the-Loop: Part III -- Grid Interconnection System Evaluator

2013 IEEE Green Technologies Conference (GreenTech), 2013

The world's energy paradigm continues to undergo a rapid shift towards an increased use of renewa... more The world's energy paradigm continues to undergo a rapid shift towards an increased use of renewable energy sources. To support this shift, an advanced electric power system architecture is being implemented by many electric utilities, interconnected with new distributed energy resources. As these new installations occur, it is essential to verify that their grid interconnection systems (ICS) conform to the relevant grid interconnection standards and that they perform satisfactorily under a variety of variable resource input and grid output conditions. This paper describes a Grid Interconnection System Evaluator (GISE) that leverages hardware-in-the-loop (HIL) simulation techniques to rapidly evaluate the grid interconnection standard conformance of an ICS according to the procedures in IEEE Std 1547.1™. The architecture and test sequencing of this evaluation tool, along with a set of representative ICS test results from three different photovoltaic (PV) inverters, are presented. The GISE adds to the National Renewable Energy Laboratory's (NREL) evaluation platform that now allows for rapid development of ICS control algorithms using controller HIL (CHIL) techniques, the ability to test the dc input characteristics of PV-based ICSs through the use of a PV simulator capable of simulating real-world dynamics using power HIL (PHIL), and evaluation of the grid interconnection conformance of an ICS.

Research paper thumbnail of Implementation and validation of advanced unintentional islanding testing using power hardware-in-the-loop (PHIL) simulation

2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013

ABSTRACT Unprecedented investment in new renewable power (especially solar photovoltaic) capacity... more ABSTRACT Unprecedented investment in new renewable power (especially solar photovoltaic) capacity is occurring. As this new generation capacity is interconnected with the electric power system (EPS), it is critical that their grid interconnection systems have proper controls in place so that they react appropriately in case of an unintentional islanding event. Advanced controls and methods for unintentional islanding protection that go beyond existing standards, such as UL 1741 and IEEE Std 1547, are often required as more complex high penetration photovoltaic installations occur. This paper describes the implementation, experimental results, and validation of a power hardware-in-the-loop (PHIL)-based platform that allows for the rapid evaluation of advanced anti-islanding and other controls in complex scenarios. The PHIL-based approach presented allows for accurate, real-time simulation of complex scenarios by connecting a device under test to a software-based model of a local EPS. This approach was validated by conducting an unintentional islanding test of a photovoltaic inverter, as described in IEEE 1547.1, using both PHIL and discrete hardware-based test configurations. The comparison of the results of these two experiments demonstrates that this novel PHIL-based test platform accurately emulates traditional unintentional islanding tests. The advantage of PHIL-based testing over discrete hardware-only testing is demonstrated by completing an IEEE 1547.1 unintentional islanding test using a very precisely tuned resonant circuit that is difficult to realize with discrete hardware using PHIL.

Research paper thumbnail of Evaluating future standards and codes with a focus on high penetration photovoltaic (HPPV) system deployment

2010 35th IEEE Photovoltaic Specialists Conference, 2010

ABSTRACT High-penetration photovoltaic (PV) system deployment is becoming a reality in several re... more ABSTRACT High-penetration photovoltaic (PV) system deployment is becoming a reality in several regions of the United States and the trend toward high penetration levels will continue to rise due to decreasing PV system costs in concert with increasing electric utility rates and societal deliberations. New standards and codes for high-penetration PV deployment must be developed, while some existing standards and codes will need to be revised to accommodate increasing levels of PV deployment. According to a recent industry report, cumulative grid-tied PV capacity in the U.S. grew to 792 MW by the end of year 2008, with a growth rate of 81% for new grid-tied PV installations in 2008 over 2007 and 53% in 2007 over 2006. These rapid growth rates are expected to continue and will be further spurred by the President's energy plan to double renewable capacity in the next three years to help the U.S. concurrently meet its economic, energy security, and environmental challenges. On May 20, 2010, in Denver, Colorado, the National Renewable Energy Laboratory, in conjunction with the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE), held a workshop to examine the key technical issues and barriers associated with high PV penetration levels. Addressing these standards and codes was a major finding of the High Penetration of PV Systems into the Distribution Grid Workshop held in Ontario, California, in February 2009.

Research paper thumbnail of Photovoltaic systems interconnected onto secondary network distribution systems

2009 34th IEEE Photovoltaic Specialists Conference (PVSC), 2009

ABSTRACT While the number of PV systems interconnected to the electric grid has increased signifi... more ABSTRACT While the number of PV systems interconnected to the electric grid has increased significantly over the last decade, only recently have PV systems been installed in major metropolitan areas and tied to electric distribution secondary network systems (networks). This paper examines six cases studies of photovoltaic (PV) systems integrated into secondary network systems. The six PV systems were chosen for evaluation because they are interconnected successfully to secondary network systems located in four major U.S. Cities.

Research paper thumbnail of On the Path to SunShot: Emerging Issues and Challenges in Integrating Solar with the Distribution System

Research paper thumbnail of Updating Technical Screens for PV Interconnection: Preprint

Solar photovoltaics (PV) is the dominant type of distributed generation (DG) technology interconn... more Solar photovoltaics (PV) is the dominant type of distributed generation (DG) technology interconnected to electric distribution systems in the United States, and deployment of PV systems continues to increase rapidly. Considering the rapid growth and widespread deployment of PV systems in United States electric distribution grids, it is important that interconnection procedures be as streamlined as possible to avoid unnecessary interconnection studies, costs, and delays. Because many PV interconnection applications involve high penetration scenarios, the process needs to allow for a sufficiently rigorous technical evaluation to identify and address possible system impacts. Existing interconnection procedures are designed to balance the need for efficiency and technical rigor for all DG. However, there is an implicit expectation that those procedures will be updated over time in order to remain relevant with respect to evolving standards, technology, and practical experience. Modifications to interconnection screens and procedures must focus on maintaining or improving safety and reliability, as well as accurately allocating costs and improving expediency of the interconnection process. This paper evaluates the origins and usefulness of the capacity penetration screen, offers potential short-term solutions which could effectively allow fast-track interconnection to many PV system applications, and considers longer-term solutions for increasing PV deployment levels in a safe and reliable manner while reducing or eliminating the emphasis on the penetration screen.

Research paper thumbnail of High-Penetration Photovoltaics Standards and Codes Workshop, Denver, Colorado, May 20, 2010: Workshop Proceedings

Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful ... more Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful technical attention to ensuring compatibility with electric power systems. Standards, codes, and implementation have been cited as major impediments to widespread use of PV within electric power systems. On May 20, 2010, in Denver, Colorado, the National Renewable Energy Laboratory, in conjunction with the U.S. Department of Energy (DOE) Office

Research paper thumbnail of Alternatives to the 15% Rule

Research paper thumbnail of Utility-Interconnected Photovoltaic Systems: Evaluating the Rationale for the Utility-Accessible External Disconnect Switch

The utility-accessible alternating current (AC) external disconnect switch (EDS) for distributed ... more The utility-accessible alternating current (AC) external disconnect switch (EDS) for distributed generators, including photovoltaic (PV) systems, is a hardware feature that allows a utility's employees to manually disconnect a customer-owned generator from the electricity grid. Proponents of the EDS contend that it is necessary to keep utility line workers safe when they make repairs to the electric distribution system. Opponents assert it is a redundant feature that adds cost without providing tangible benefits.

Research paper thumbnail of Updating Interconnection Screens for PV Integration Can Streamline Deployment

Research paper thumbnail of Interconnecting PV on New York City's Secondary Network Distribution System

Laboratory (NREL) and Con Edison, the local utility, to develop a roadmap for photovoltaic (PV) i... more Laboratory (NREL) and Con Edison, the local utility, to develop a roadmap for photovoltaic (PV) installations in the five boroughs. The city set a goal to increase its installed PV capacity from 1.1 MW in 2005 to 8.1 MW by 2015 (the maximum allowed in 2005). A key barrier to reaching this goal, however, is the complexity of the interconnection process with the local utility. Unique challenges are associated with connecting distributed PV systems to secondary network distribution systems (simplified to "networks" in this report).

Research paper thumbnail of High-Penetration Photovoltaics Standards and Codes Workshop, Denver, Colorado, May 20, 2010: Workshop Proceedings

Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful ... more Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful technical attention to ensuring compatibility with electric power systems. Standards, codes, and implementation have been cited as major impediments to widespread use of PV within electric power systems. On May 20, 2010, in Denver, Colorado, the National Renewable Energy Laboratory, in conjunction with the U.S. Department of Energy (DOE) Office

Research paper thumbnail of Assessing technical potential for city PV deployment using NREL's in my backyard tool

2010 35th IEEE Photovoltaic Specialists Conference, 2010

Page 1. ASSESSING TECHNICAL POTENTIAL FOR CITY PV DEPLOYMENT USING NREL'S IN MY BACKYARD TOOL... more Page 1. ASSESSING TECHNICAL POTENTIAL FOR CITY PV DEPLOYMENT USING NREL'S IN MY BACKYARD TOOL Kate H. Anderson1, Michael H. Coddington1, Benjamin D. Kroposki1, 1National Renewable Energy Laboratory, Golden, Colorado, USA ABSTRACT ...

Research paper thumbnail of Current Utility Screening Practices, Technical Tools, Impact Studies, and Mitigation Strategies for Interconnecting PV on the Electric Distribution Systems

Research paper thumbnail of Beta Test Plan for Advanced Inverters Interconnecting Distributed Resources with Electric Power Systems

Research paper thumbnail of National Renewable Energy Laboratory Golden, CO

National Renewable Energy Laboratory (formerly the Solar Energy Research Institute) 1617 Cole Bou... more National Renewable Energy Laboratory (formerly the Solar Energy Research Institute) 1617 Cole Boulevard Golden, Colorado 80401-3393 Operated by the Midwest Research Institute for the US Department of Energy under Contract No. DE-ACO2-83CH10093

Research paper thumbnail of Summary of Electric Distribution System Analyses with a focus on DERs

Research paper thumbnail of Field Guide for Testing Existing Photovoltaic Systems for Ground Faults and Installing Equipment to Mitigate Fire Hazards

Research paper thumbnail of IEEE 1547 Standards advancing grid modernization

2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC), 2015

Research paper thumbnail of Ultra-low viscosity epoxy sealer/healer

Research paper thumbnail of An Advanced Platform for Development and Evaluation of Grid Interconnection Systems Using Hardware-in-the-Loop: Part III -- Grid Interconnection System Evaluator

2013 IEEE Green Technologies Conference (GreenTech), 2013

The world's energy paradigm continues to undergo a rapid shift towards an increased use of renewa... more The world's energy paradigm continues to undergo a rapid shift towards an increased use of renewable energy sources. To support this shift, an advanced electric power system architecture is being implemented by many electric utilities, interconnected with new distributed energy resources. As these new installations occur, it is essential to verify that their grid interconnection systems (ICS) conform to the relevant grid interconnection standards and that they perform satisfactorily under a variety of variable resource input and grid output conditions. This paper describes a Grid Interconnection System Evaluator (GISE) that leverages hardware-in-the-loop (HIL) simulation techniques to rapidly evaluate the grid interconnection standard conformance of an ICS according to the procedures in IEEE Std 1547.1™. The architecture and test sequencing of this evaluation tool, along with a set of representative ICS test results from three different photovoltaic (PV) inverters, are presented. The GISE adds to the National Renewable Energy Laboratory's (NREL) evaluation platform that now allows for rapid development of ICS control algorithms using controller HIL (CHIL) techniques, the ability to test the dc input characteristics of PV-based ICSs through the use of a PV simulator capable of simulating real-world dynamics using power HIL (PHIL), and evaluation of the grid interconnection conformance of an ICS.

Research paper thumbnail of Implementation and validation of advanced unintentional islanding testing using power hardware-in-the-loop (PHIL) simulation

2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013

ABSTRACT Unprecedented investment in new renewable power (especially solar photovoltaic) capacity... more ABSTRACT Unprecedented investment in new renewable power (especially solar photovoltaic) capacity is occurring. As this new generation capacity is interconnected with the electric power system (EPS), it is critical that their grid interconnection systems have proper controls in place so that they react appropriately in case of an unintentional islanding event. Advanced controls and methods for unintentional islanding protection that go beyond existing standards, such as UL 1741 and IEEE Std 1547, are often required as more complex high penetration photovoltaic installations occur. This paper describes the implementation, experimental results, and validation of a power hardware-in-the-loop (PHIL)-based platform that allows for the rapid evaluation of advanced anti-islanding and other controls in complex scenarios. The PHIL-based approach presented allows for accurate, real-time simulation of complex scenarios by connecting a device under test to a software-based model of a local EPS. This approach was validated by conducting an unintentional islanding test of a photovoltaic inverter, as described in IEEE 1547.1, using both PHIL and discrete hardware-based test configurations. The comparison of the results of these two experiments demonstrates that this novel PHIL-based test platform accurately emulates traditional unintentional islanding tests. The advantage of PHIL-based testing over discrete hardware-only testing is demonstrated by completing an IEEE 1547.1 unintentional islanding test using a very precisely tuned resonant circuit that is difficult to realize with discrete hardware using PHIL.

Research paper thumbnail of Evaluating future standards and codes with a focus on high penetration photovoltaic (HPPV) system deployment

2010 35th IEEE Photovoltaic Specialists Conference, 2010

ABSTRACT High-penetration photovoltaic (PV) system deployment is becoming a reality in several re... more ABSTRACT High-penetration photovoltaic (PV) system deployment is becoming a reality in several regions of the United States and the trend toward high penetration levels will continue to rise due to decreasing PV system costs in concert with increasing electric utility rates and societal deliberations. New standards and codes for high-penetration PV deployment must be developed, while some existing standards and codes will need to be revised to accommodate increasing levels of PV deployment. According to a recent industry report, cumulative grid-tied PV capacity in the U.S. grew to 792 MW by the end of year 2008, with a growth rate of 81% for new grid-tied PV installations in 2008 over 2007 and 53% in 2007 over 2006. These rapid growth rates are expected to continue and will be further spurred by the President's energy plan to double renewable capacity in the next three years to help the U.S. concurrently meet its economic, energy security, and environmental challenges. On May 20, 2010, in Denver, Colorado, the National Renewable Energy Laboratory, in conjunction with the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE), held a workshop to examine the key technical issues and barriers associated with high PV penetration levels. Addressing these standards and codes was a major finding of the High Penetration of PV Systems into the Distribution Grid Workshop held in Ontario, California, in February 2009.

Research paper thumbnail of Photovoltaic systems interconnected onto secondary network distribution systems

2009 34th IEEE Photovoltaic Specialists Conference (PVSC), 2009

ABSTRACT While the number of PV systems interconnected to the electric grid has increased signifi... more ABSTRACT While the number of PV systems interconnected to the electric grid has increased significantly over the last decade, only recently have PV systems been installed in major metropolitan areas and tied to electric distribution secondary network systems (networks). This paper examines six cases studies of photovoltaic (PV) systems integrated into secondary network systems. The six PV systems were chosen for evaluation because they are interconnected successfully to secondary network systems located in four major U.S. Cities.

Research paper thumbnail of On the Path to SunShot: Emerging Issues and Challenges in Integrating Solar with the Distribution System

Research paper thumbnail of Updating Technical Screens for PV Interconnection: Preprint

Solar photovoltaics (PV) is the dominant type of distributed generation (DG) technology interconn... more Solar photovoltaics (PV) is the dominant type of distributed generation (DG) technology interconnected to electric distribution systems in the United States, and deployment of PV systems continues to increase rapidly. Considering the rapid growth and widespread deployment of PV systems in United States electric distribution grids, it is important that interconnection procedures be as streamlined as possible to avoid unnecessary interconnection studies, costs, and delays. Because many PV interconnection applications involve high penetration scenarios, the process needs to allow for a sufficiently rigorous technical evaluation to identify and address possible system impacts. Existing interconnection procedures are designed to balance the need for efficiency and technical rigor for all DG. However, there is an implicit expectation that those procedures will be updated over time in order to remain relevant with respect to evolving standards, technology, and practical experience. Modifications to interconnection screens and procedures must focus on maintaining or improving safety and reliability, as well as accurately allocating costs and improving expediency of the interconnection process. This paper evaluates the origins and usefulness of the capacity penetration screen, offers potential short-term solutions which could effectively allow fast-track interconnection to many PV system applications, and considers longer-term solutions for increasing PV deployment levels in a safe and reliable manner while reducing or eliminating the emphasis on the penetration screen.

Research paper thumbnail of High-Penetration Photovoltaics Standards and Codes Workshop, Denver, Colorado, May 20, 2010: Workshop Proceedings

Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful ... more Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful technical attention to ensuring compatibility with electric power systems. Standards, codes, and implementation have been cited as major impediments to widespread use of PV within electric power systems. On May 20, 2010, in Denver, Colorado, the National Renewable Energy Laboratory, in conjunction with the U.S. Department of Energy (DOE) Office

Research paper thumbnail of Alternatives to the 15% Rule

Research paper thumbnail of Utility-Interconnected Photovoltaic Systems: Evaluating the Rationale for the Utility-Accessible External Disconnect Switch

The utility-accessible alternating current (AC) external disconnect switch (EDS) for distributed ... more The utility-accessible alternating current (AC) external disconnect switch (EDS) for distributed generators, including photovoltaic (PV) systems, is a hardware feature that allows a utility's employees to manually disconnect a customer-owned generator from the electricity grid. Proponents of the EDS contend that it is necessary to keep utility line workers safe when they make repairs to the electric distribution system. Opponents assert it is a redundant feature that adds cost without providing tangible benefits.

Research paper thumbnail of Updating Interconnection Screens for PV Integration Can Streamline Deployment

Research paper thumbnail of Interconnecting PV on New York City's Secondary Network Distribution System

Laboratory (NREL) and Con Edison, the local utility, to develop a roadmap for photovoltaic (PV) i... more Laboratory (NREL) and Con Edison, the local utility, to develop a roadmap for photovoltaic (PV) installations in the five boroughs. The city set a goal to increase its installed PV capacity from 1.1 MW in 2005 to 8.1 MW by 2015 (the maximum allowed in 2005). A key barrier to reaching this goal, however, is the complexity of the interconnection process with the local utility. Unique challenges are associated with connecting distributed PV systems to secondary network distribution systems (simplified to "networks" in this report).

Research paper thumbnail of High-Penetration Photovoltaics Standards and Codes Workshop, Denver, Colorado, May 20, 2010: Workshop Proceedings

Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful ... more Effectively interconnecting high-level penetration of photovoltaic (PV) systems requires careful technical attention to ensuring compatibility with electric power systems. Standards, codes, and implementation have been cited as major impediments to widespread use of PV within electric power systems. On May 20, 2010, in Denver, Colorado, the National Renewable Energy Laboratory, in conjunction with the U.S. Department of Energy (DOE) Office

Research paper thumbnail of Assessing technical potential for city PV deployment using NREL's in my backyard tool

2010 35th IEEE Photovoltaic Specialists Conference, 2010

Page 1. ASSESSING TECHNICAL POTENTIAL FOR CITY PV DEPLOYMENT USING NREL'S IN MY BACKYARD TOOL... more Page 1. ASSESSING TECHNICAL POTENTIAL FOR CITY PV DEPLOYMENT USING NREL'S IN MY BACKYARD TOOL Kate H. Anderson1, Michael H. Coddington1, Benjamin D. Kroposki1, 1National Renewable Energy Laboratory, Golden, Colorado, USA ABSTRACT ...