A piecewise probabilistic harmonic power flow approach in unbalanced residential distribution systems

With the improvement of living standards and economic growth, the electricity consumption of Chinese residents is increasing year by year. Due to the existence of many nonlinear devices in residential loads, a large number of time-varying harmonic currents are randomly injected into the residential distribution system (RDS), which makes it difficult for a single deterministic harmonic power flow (HPF) method to evaluate the probabilistic and time-varying harmonics of residential loads. In this paper, a piecewise probabilistic HPF method is proposed to evaluate the harmonic emission level. First, a piecewise probabilistic harmonic coupled model (HCM) is used to analyze the harmonic generated by residential loads, which can demonstrate the probabilistic and time-varying harmonic characteristics. Second, based on the HCM, a decoupled approach combing the graph theory and current injection method is established to calculate the HPF with residential loads. Third, based on the HCM and HPF calculation method, a field theory is used to evaluate the probabilistic harmonics of an unbalanced RDS. Field measurement results in different residential areas and simulation results in IEEE-13, 123, and 8500 test systems verify the accuracy, validity, and efficiency of the proposed model and calculation methods.

Automated summary

The piecewise probabilistic HPF method proposed in this paper can effectively evaluate the harmonic emission level of residential loads. This method combines the piecewise probabilistic harmonic coupled model and the decoupled calculation method, and uses field theory to evaluate the probabilistic harmonics of unbalanced residential distribution systems.