Impact of soft open point on feeder automation

Soft open points (SOPs) are power electronic devices installed in place of normally open points in distribution networks. SOPs are implemented using back-to-back voltage source converters (VSCs), which allows independent control of real and reactive power flowing through their AC terminals. This paper studies the impact of using SOPs on an existing feeder automation scheme under balanced fault conditions. The operation of the network without an SOP is used as a base case for comparison. Simulations were carried out on a network model developed in the EMTDC/PSCAD simulation platform. An algorithm for the control of the SOP is proposed. It uses error suppressor and voltage-frequency droop control to ensure that the SOP does not contribute to the fault. Simulation results show that the SOP can perform adequately without interrupting the sequence of operation in the existing feeder automation scheme and, in addition, can continue to provide reactive power support to an unfaulted feeder.