Fuzzy collaborative reactive power control in group of roof-top photovoltaic systems

In order to hold the international pledge of reducing 25% of CO₂ emission, Japanese government is now promoting the installation of roof-top photovoltaic (PV) to residential areas. One of the technical issues arising here is the countermeasure how we can keep voltage profile, the regulation on which might be easily violated by the reverse power flow from PVs particularly near ends of distribution feeders. This paper proposes a new collaborative control method for the purpose of voltage profile improvement utilizing the unused reactive capability in PV inverters and a step voltage regulator (SVR) by a collaborative manner. Its control logic is based on a rule base using triangular shaped membership functions. Numerical simulations show that the total amount of PV power output can be increased by the proposed method. Also shown is the possibility of suppressing the increase in the distribution loss by appropriate usage of SVR.