Reducing the active power curtailment of distributed generation based on soft open points in unbalanced distribution networks

Abstract

Voltage profiles may exceed the upper limit in a distribution network with a high penetration of distributed generation (DG). Voltage can be effectively regulated by curtailing the active power of DG and adjusting the reactive power. Soft open points (SOPs) have flexible active power transfer and reactive power regulation capabilities that can help reduce the active power curtailment of DG. Asymmetric network parameters, single-phase loads, and DGs cause voltage unbalance in distribution networks. This study proposes an optimal power control model of SOPs and DG converters in unbalanced distribution networks (UDNs). First, the individual phase power control characteristics of SOPs and DG converters in UDNs are modelled. Second, an optimisation model is constructed with the minimum active power curtailment of DG and the total power loss and voltage unbalance of UDNs as the objective function and with consideration of the networks and SOP operation constraints. The original optimisation model with non-convex and non-linear characteristics is transformed using power flow linearisation and linear relaxation into a linear programming model that can be efficiently solved. Finally, the feasibility and efficiency of the proposed model are verified using an IEEE 33-node system.