Integration of micro-scale photovoltaic distributed generation on power distribution systems: Dynamic analyses

Grid-connected solar photovoltaic distributed generation (PV-DG) units offer many benefits such as clean energy, reduced emissions and creation of new green jobs. A combination of supportive legislation, incentives, technology developments and costs decrease have favored the proliferation of PV-DG plants of different capacities, ranging from a few kVA (small-scale) to several MVA (large-scale). Due to its intermittent nature, increasing penetration of large-scale PV-DG may lead to potential impacts on planning and operations of power distribution systems. Recently, highly distributed small size PV-DG (using panel-level PV inverters) and new inverter controls have emerged as an alternative to existing centralized inverter technologies. This paper discusses potential impacts and benefits of large-scale and micro-scale PV-DG based on conventional power factor control and Generator Emulator Control (GEC) for PV inverters. Impacts of interest for this paper are those of dynamic nature due to output intermittency that may lead to distribution feeder voltage fluctuations and operation of conventional automatic voltage control devices of a feeder. The paper presents results of detailed simulations conducted on a real-life 12.47 kV utility feeder and shows a comparison of the expected impacts and benefits of using different PV-DG technologies and inverter control modes.