Low Cost Solutions for Balancing Three Phase Feeders to SWER Systems

Abstract

Single wire earth return systems, (SWER), are widely used in sparsely settled regions and are a very low cost distribution solution. As the SWER systems are connected as phase to phase loads, the three phase side of a SWER feeder transformer can see significant unbalance. Although effort is made to balance the loads,this can not be entirely achieved. Currently, tap changing voltage regulators are used in either an open or closed delta to provide magnitude compensation, however this still leaves the possibility of phase unbalance. As one major feature of SWER is the low capital cost, it is necessary to explore the feasibility of any proposed solution to ensure that the cost is not prohibitive. A simple, low cost solution uses switched capacitor compensation and this approach is explored, using simulation, to determine the cost effectiveness and practicality. The simulation case study gives an indication of the rating of the capacitors required and the applicable control strategies. The results indicate a feasible, low cost solution applicable to SWER systems.