Overall performance evaluation of reactive power control strategies in low voltage grids with high prosumer share

Abstract

This paper presents an overall evaluation of different reactive power control strategies in low voltage grids with high prosumer share by means of social and technical criteria. Two types of control-devices, which fundamentally differ in their ownership structure, are considered: prosumer-owned photovoltaic-inverters and distribution system operator-owned inductive devices. Local cosφ(P)- and Q(U)-control of photovoltaic-inverters and local L(U)-control of inductive devices are separately simulated in various low voltage grids with radial structure and different cable share. L(U)-control is calculated also in presence of Q-Autarkic prosumers. Results show that the use of prosumer-owned PV-inverters to eliminate voltage violations on the feeder entails social and technical disadvantages such as prosumer discrimination, threat to their data privacy, high reactive power exchanges between low and medium voltage grid, high distribution transformer loading and high grid loss. In rural networks with relative long feeders and high PV-penetrations, the use of local controls of prosumer-owned inverters is not sufficient to eliminate all violations of the upper voltage limit. The application of inductive devices for voltage control does not entail social issues and enables a satisfactory technical performance of low voltage grids. The combination of L(U)-control and Q-Autarkic prosumers further improves the grid performance. Results show that the cosφ(P)-control strategy has the worst overall performance, while L(U)-control combined with Q-Autarkic prosumers has the best one.