Series controllers in distribution systems: facilitating increased loading and higher DG penetration

Medium voltage distribution feeders are generally not loaded to their nominal rating because of redundancy considerations. During repair of a faulted feeder the loads will be switched to another feeder to limit the customer interruption time. This spare capacity needs to be reserved on each of the concerned cables. Another issue in medium voltage distribution systems is that the increasing penetration of distributed generation (DG) may cause low voltage customer voltages to go outside normative limits. To make some of the spare capacity available for increased loading and to allow higher DG penetration levels without causing excess voltage fluctuations, the application of a series controller is proposed. This paper shows simulations of cable distribution systems both with and without series controllers, and compares the results. It is shown how series controllers can increase the maximum loading and the maximum DG penetration level of distribution systems