Investigations into the issue of reactive power sharing amongst photovoltaic based distributed generators operating in a microgrid

Abstract

quotA microgrid (MG) provides promising option for future electricity generation by incorporating electricity generation from non-conventional or renewable energy sources. The share of electricity generation from renewable sources is increasing rapidly in the grid or MG. It is mainly due to the depletion of conventional energy sources, increasing cost of these sources and growing environmental concern. Amongst various renewable energy sources, photovoltaic (PV) has emerged as one of the most potential energy sources to provide clean energy. However, increased penetration of PV sources has also given rise to several challenges. One of these challenges is reactive power management through the PV inverters. newline newlineUsually, the PV inverters are operated to exchange mainly active power with the main grid. However, the PV inverters do have the capability to exchange the reactive power with the grid or microgrid. Several studies have focused on the reactive power control through PV based inverters. However, often the impact of the variable active power from the PV array on the available reactive power margin is ignored. It may lead to overloading of the inverters or unequal utilization of the resources. newline newlineIn this research, reactive power sharing algorithms are proposed which takes into account the variable nature of the active power available from the PV based DGs and then distributes the reactive power amongst the various DGs based on the available reactive power margins. The algorithms proposed as Equal Apparent Power assigns the reactive power amongst the DGs having identical ratings in such a way that the gap amongst the utilization factors of these inverters decreases. However, it is observed that the order in which the reactive power is allocated amongst the inverters, affects the standard deviation of the utilization factors of the inverters. Hence, the algorithm is further modified and proposed as Equal power sharing with least standard deviation (EAPS-LSD) to take into account the order/sequence in which the reactiv