Determination of the main unbalance sources on PCC in the distribution system

This paper proposes a method to determine the main unbalance sources on the point of common coupling (PCC) in the distribution system. The unbalance sources in the upstream side are proposed to be equivalent as a Thevenin voltage source, while the unbalance sources in the downstream side are equivalent as an unbalanced current source. An unbalance contribution factor is proposed to determine the contribution of the upstream and downstream unbalance sources. Moreover, the upstream Thevenin equivalent circuit is estimated based on the measured PCC voltages and currents using the complex least-square method. Simulation results verify the validity and accuracy of the proposed method.