Integration of Centralized and Local Voltage Control Scheme in Distribution Network to Reduce the Operation of Mechanically Switched Devices

Abstract

Q(U) control for PV inverter has become the mandatory local voltage controller to comply with the grid connection code at Medium Voltage level CLC-FprTS 50549- 2. The parameters of Q(U) control is optimized day ahead for which the tap operation is not generally taken into account. As a result, the optimal dead-band of Q(U) controller could be larger than the dead-band of On Load Tap Changer, which leads to an increased number of tap operation during intermittent irradiation day. Considering this problem, the paper proposes the MPC based centralized controller to assist the local control for modifying their Q(U) characteristics primarily to suppress the number of tap operation and also participate all the inverter for tighter voltage regulation. The proposed method is implemented in a test distribution network modeled in DigSilent. Finally, the effectiveness of the method is shown using RMS simulation method.