Solar Energy (Photovolatics)
The North American Bulk Power System (BPS) and electric transmission grids around the world are undergoing rapid changes in generation resource mix with increasing amounts of renewable generation such as wind and solar photovoltaic (PV) power plants. These resources are asynchronously connected to the grid and are either completely or partially interfaced with the BPS through power electronics, hence referred to as inverter-based resources. The power electronics aspects of these generating resources present new opportunities in terms of grid control and response to abnormal grid conditions. Regardless of the type of resource, it is paramount that all BPS-connected resources are capable of providing essential reliability services (ERSs) and operate in a manner that supports BPS reliability. Recently, the North American Electric Reliability Corporation (NERC) has been conducting analyses of BPS-connected solar PV generating plants and their response to transmission disturbances. To support these analyses, NERC formed the Inverter-Based Performance Task Force (IRPTF) in 2017, consisting of experts from multiple sectors of the electric industry. Among the first cases analyzed were the 2016 Blue Cut Fire and 2017 Canyon 2 Fire events in the Southern California. These transmission fault events caused the unintended tripping of significant amounts of solar photovoltaic (PV) generation capacity. The IRPTF analyses and subsequent reports on these events identified several causes and corrective measures which have been communicated to generators owners/operators. NERC issued industry advisories in an effort to inform registered entities of the potential risk of tripping as well as recommend mitigating actions. Recognizing the need for additional industry guidance, the IRPTF drafted a Reliability Guideline for Inverter-Based Resource Performance in 2018, published by NERC, which provides comprehensive technical guidance for the recommended behavior of inverter-based resources connected to the BPS. The material presented throughout the guideline is based on extensive research, system modeling, and discussions with industry experts and members of the IRPTF. This guideline is now forming the basis of proposed revisions to NERC standards as well as the new IEEE Standard P2800, Interconnection and Interoperability of Inverter-Based Resources Interconnecting with Associated Transmission Electric Power Systems. The IRPTF also plans to issue a NERC Reliability Guideline for Improvements to Interconnection Requirements for Inverter-Based Resources, that is intended to provide specific technical recommendations for interconnection requirements (grid codes, interconnection agreements, etc.) between the owners of inverter-based resources and transmission operators. This will cover a wide range of related aspects from dynamic performance, protective functions, to plant monitoring capability. The presentation proposed for the Technical Symposium will cover the multiple aspects of inverter-based resource performance recommended by the NERC IRPTF.