A balance compensation method based on negative sequence weighted equivalent model of unbalanced load

Abstract

when designing a passive network to compensate unbalanced load, an ideal and balanced voltage source is usually taken to generate the voltage at the point of common coupling (PCC), but the compensation results is not so good due to the unbalance of PCC voltage in real systems. With regard to three- phase three-wire circuit, the system side is equivalent to Thevenin model, and the negative sequence current of the load is decomposed into three parts, after being weighted and allotted into three phases, each part then rotates to the positive sequence. Based on the above procedure, the negative sequence weighted equivalent model of three-phase unbalanced load is established in this paper. With equivalent load parameters, the negative- sequence-weighted formula of passive compensation network parameters is presented utilizing the Steinmetz theory. Since the network parameters are functions of negative-sequence-weights, the proposed compensation method can provide a theoretical basis for optimal balance compensation. Simulation results verify the validity of the equivalent model and compensation method proposed.