Voltage rise suppression by reactive power control with cooperating photovoltaic generation systems

Increasing interconnections of photovoltaic generation systems (PV systems) may result in difficulties of voltage management on distribution lines. Fortunately, grid interactive inverters used in the PV systems often have some surplus capacity all through the day. Therefore, it is useful to utilize the surplus capacities of the grid interactive inverters for the line voltage management. This paper aims at developing a voltage rise mitigation method by the grid interactive inverters of the PV systems with cooperating each other by a simple information network. In this method, each inverter decides its output reactive power autonomously at first, and continuously modifying it based on an additional control signal for cooperation with the other inverters. The additional control signal is very effective for utilizing the small capacities of the inverters because it can equalize the duties of the inverters. However, one of the most important issues is how to give the additional signals to the many distributed inverters. In order to find a better solution, it is demonstrated by some simulation results how the density of the additional control signal influences the effectiveness of the voltage management and the required reactive power.