Coordinated voltage control in distribution systems with DG — Control algorithm and case study

Distributed generation (DG) in medium voltage distribution networks has become widespread during the last years. Distribution networks are normally planned and built to cope with decreasing voltage from the substation along the feeders. With a high DG penetration the power flow can be reversed in some feeders during some time periods and thus the voltage increases along the feeder. In this paper an improved voltage control algorithm for a more active voltage control in medium voltage networks is presented and tested by simulations in an existing network. By using coordinated control of the DG units´ active and reactive power as well as the on-load tap changer (OLTC), the DG hosting capacity can be increased without expensive network reinforcement. In the test case it was possible to increase the DG capacity from present 13 MW to 38 MW without the need of network reinforcements.