Smart Solar PV Inverters with Advanced Grid Support Functionalities. Rajiv K. Varma

obtained B.Tech. and Ph.D. degrees in Electrical Engineering from the Indian Institute of Technology (IIT) Kanpur, India, in 1980 and 1988, respectively. He started his academic career as an Assistant Professor at the Indian Institute of Technology Kanpur, in 1989. He was awarded the Government of India BOYSCAST Young Scientist Fellowship in 1992–1993 to conduct research on FACTS at the University of Western Ontario, London, Canada. He continued as a Visiting Assistant Professor at UWO until December 1994. He returned to IIT Kanpur and was promoted to Associate Professor in 1997. He was awarded the Fulbright Travel Grant of the U.S. Educational Foundation in India to travel to the United States in 1998 and do research in High Voltage DC (HVDC) transmission and FACTS at Bonneville Power Administration, U.S. Dept. of Energy, Portland, Oregon. He became a Professor at the Indian Institute of Technology Kanpur, in 2001 prior to joining the University of Western Ontario in December 2001.

      Dr. Varma has held Adjunct Professor positions at the University of Waterloo and Ryerson University, Toronto. He is Senior Member of IEEE, a Member of CIGRE, and also a licensed Professional Engineer in the province of Ontario.

      FOREWORD

      During the course of my 33‐year career to date, I have had the privilege to contribute to a wide variety of activities associated with the application of Flexible AC Transmission Systems (FACTS) Controllers to improve power system dynamic behavior. This interest has taken me on a career journey with two different manufacturers, including direct experience on numerous utility‐scale FACTS installations.

      Through our mutual interest with the application of power electronics‐based equipment to improve power system dynamic behavior, it was inevitable that Rajiv and I would meet by way of our common activities and volunteer work within the IEEE Power & Energy Society (PES) Transmission and Distribution (T&D) Committee and its HVDC and FACTS Subcommittee and participate in a number of its working groups including Performance and Modeling, Economics and Operating Strategies, and Education. Rajiv and I also interacted over the years on the subject of FACTS Controllers in the IEEE PES Substations Committee in multiple subcommittees and working groups. In addition, when I was an instructor in Bill Long's University of Wisconsin Engineering Professional Development program on the Dynamic Reactive Power Control Short Course series, Rajiv's book titled “Thyristor‐Based FACTS Controllers for Electrical Transmission Systems,” was the text for several editions of that course. Through these experiences, I became quite familiar with Rajiv’s work and contributions to FACTS and smart solar photovoltaic (PV) inverters.

      With the advent of more cost‐effective equipment, along with the growing interest in decarbonization via renewable generation, the utilization of solar PV installations has grown significantly over the past decade and more. The application of this technology will continue to grow in the coming years as government mandates for Renewables Portfolio Standards (RPS) (or equivalent) increase and expand, while the total costs of PV installations continue to decrease. Beyond standard PV installations, which primarily focus on the control of the active power generated by the solar panels, lie opportunities for the application of smart solar PV inverters. Through advanced controls, smart solar PV inverters utilize the full range of capability for both active and reactive power, which in turn allows for a variety of benefits to improve power system dynamic behavior. These concepts are highlighted in detail in the various pages of this book.

Around 2009, Rajiv began to develop ground‐breaking techniques to transform solar PV inverters into the performance of a STATCOM, which provides various functionalities both during the night and day. Rajiv termed this advancement as PV‐STATCOM, which is essentially a new FACTS Controller. The PV‐STATCOM controls can provide several advanced grid support functions such as dynamic voltage control, power oscillation damping, mitigation of subsynchronous control interactions and torsional oscillations, improved Fault‐Induced Delayed Voltage Recovery (FIDVR), stabilization of remote critical motors, and fast frequency response, all of which can lead to improved dynamic performance, increased power transfer and load serving, and enhanced connectivity of neighboring wind plants and solar plants. It is worth noting that the PV‐STATCOM technology is about 10 times more economical than an equivalent‐sized STATCOM. This advancement by Rajiv, along with a field demonstration for the first time in 2016, is described in the various pages of this book in several chapters.

      Rajiv, by providing this book to the industry, captures his career‐long dedication to, and knowledge of, power electronics‐based systems to improve dynamic performance. This book is a timely addition on the growing topic of smart solar PV installations. The topics cover a wide range of interest from smart PV inverter functions, modeling and control, applications (both distribution and transmission), hosting capacity, coordinated control, and emerging trends. The treatment further supports the characterization that the smart solar PV inverter, designated as PV‐STATCOM, is a new FACTS Controller. This book will be of great interest from beginners to experts in academia, research, and industry of all competencies including utilities, system operators, developers, integrators, regulators, manufacturers, and beyond.

      John Paserba, Fellow IEEE

      Vice President, Power Systems Group Mitsubishi Electric Power Products, Inc. (MEPPI) Warrendale, PA, USA

      PREFACE

      Solar photovoltaic (PV) systems are the fastest growing renewable energy systems, worldwide. It is expected that by 2050 about 35% of global electricity will be provided by solar PV systems. While this technology is helping reduce greenhouse gas emissions and meeting the climate targets for the planet, researchers worldwide have been engaged in developing technologies for additional and novel usages of solar systems.

      Solar PV systems are based on inverters which have traditionally provided only active power generation from solar energy. Power electronics however allows several additional capabilities to be realized from the same inverters which can be of tremendous benefit in enhancing the stability and reliability of power systems. Efforts have been ongoing worldwide to develop such “advanced” or “smart” functionalities on solar PV inverters. Such inverters have been termed as “advanced inverters” or more commonly as “smart inverters.” Smart inverter functions have been shown to not only mitigate the problems of integration of solar systems themselves but also to alleviate challenges in power systems caused by other sources, such as disturbance events. The developments of smart inverter functionalities have outpaced the Standards responsible for integrating solar PV systems in the grid. The interest and engagement of academics, utilities, system planners, regulators, operators, and manufacturers in the development of the smart inverter technologies is very high.

      A wealth of literature has been published over the last two decades describing the controls, simulation studies, laboratory implementations and operating experiences of various functionalities of smart inverters, which continues to grow every day at a very rapid pace. Unfortunately, this invaluable literature is scattered and not available in a comprehensive form.

      In 2008, the province of Ontario in Canada undertook a major initiative to develop innovative technologies for integrating solar PV systems at a large scale in transmission and distribution systems. The author of this book was privileged to be selected to lead three highly funded ($8.2 Million) multi‐university multi‐disciplinary multi‐utility research grants in Ontario to achieve this objective. During this period, the author developed a new patented technology of utilizing solar PV systems in the night and day as STATic Synchronous COMpensator (STATCOM), naming it PV‐STATCOM, for providing various grid support functionalities which are typically provided by Flexible AC Transmission System (FACTS).

The author was also fortunate to be the team‐lead for the first‐time delivery of the IEEE Tutorial on “Smart Inverters” with leading experts from EPRI, NREL, National Grid, Southern California Edison, Enphase Energy, and First Solar. This Tutorial was delivered with great success for four consecutive years in IEEE Power & Energy Society (PES) Conferences.