Study on Reactive Power Compensation using Available Capacity of PCS of PV Systems in High Voltage Distribution Network

Abstract

The installed capacity of photovoltaic (PV) systems has been increasing rapidly due to the enforcement of the feed-in tariff scheme in Japan. However, reverse power flows from PV systems cause voltage rise in distribution networks. As one of the ways to avoid voltage rise, there is a constant power factor control by Power Conditioning Subsystem of PV (PV-PCS). In long-distance distribution networks, however, constant power factor control could cause voltage drop; in addition, rapid load changes cause voltage fluctuation problems. Static Var Compensator (SVC) can solve these problems, but it is high cost. Therefore, it is more economical to use PV-PCS than to install SVC. In this paper, we propose variable power factor control and reactive power compensation using available capacity of PV-PCS. While the variable power factor control maximizes PV power generation for PV owners, the available capacity of PV-PCS supplies reactive power to suppress voltage fluctuations, which is equivalent to SVC for electric utilities. The result shows that the variable power factor control can increases PV power generation more than constant power factor control. We clarified a range of available capacity of PV-PCS to supply reactive power that generates a Win-Win situation for PV owners and electric utilities.