Voltage control of unbalanced distribution system with wind energy conversion system and high photovoltaic penetration

This paper presents a voltage control method which is able to mitigate the voltage fluctuations caused by the integration of directly connected wind energy conversion system (WECS) based on induction generator (IG) into an unbalanced distribution system. Photovoltaic (PV) systems are widely spread in the distribution systems thus the proposed method takes into consideration high penetration of PV systems´ effect especially voltage deviations. The method is based on the use of the available reactive power in the inverters interfaced with PV systems for voltage control. However, in the connection point (CP) with the directly connected IG based WECS, the PV inverter will be used to control the voltage, compensate the reactive power needed by the WECS and smooth the fast voltage variation caused by the wind speed fluctuations. Since the distribution system is considered to be unbalanced, the directly connected IG based WECS three-phase model has been taken into account as well as the other components three-phase model and the powerflow solution method. Simulations have been conducted on a 14-bus system with high penetration and one IG based WECS to evaluate the proposed control method.