Voltage Stabilization with Reactive Power Compensation by Demand Side Equipment

—Cost-effectiveness Analysis Method Considering PV Output Curtailment—

Abstract

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-rises in distribution networks. As for the voltage stabilization with reactive power compensation, SVC (Static Var Compensator) has been installed until now. On the other hand, reactive power compensation using demand side equipment is proposed as a promising alternative with its cost-effectiveness. This paper proposes a cost-effectiveness analysis method of reactive power compensators considering PV output curtailment and reveals the conditions that demand side equipment has a cost advantage. First, we defined an annual cost as the sum of annual equipment cost of reactive power compensators and opportunity cost associated with PV curtailment, then calculated an optimum curtailment ratio, which minimizes the annual cost. Through the analysis, we obtained following findings: (1) the higher the avoided cost is, the lower the optimum curtailment ratio is; (2) the higher the annual equipment cost of demand side equipment is, the higher the optimum curtailment ratio is; (3) the higher the PV penetration rate is, the higher the optimum curtailment ratio is. This is because as for the cost impact arising from increasing PV, the annual equipment cost is greater than the opportunity cost associated with PV output curtailment.