Harmonic Modeling And Resonance Analysis Of Residential Loads

With the general application of power electronic based residential loads in distribution network,very considerable collective harmonics and possible harmonic resonance problems that have non-negligible impacts on the power systems have been generated.Therefore,the qualitative and quantitative analysis of the resonance problem in the distribution network is of great significance to improve the damage of the resonance.The harmonics produced by the residential loads are obviously different from those produced by the traditional industrial loads,mainly because of the dispersion of the residential loads in the distribution system and the uncertainty of their working conditions,therefore the effective modeling of residential loads is the premise to study and evaluate harmonic resonance problems.Current modeling methods have the disadvantages of large computation and low model accuracy,Which are difficult to research on large scale residential loads modeling.In order to solve these problems,we introduces the theory of probability modeling and improve it.So an analytical model to characterize the random work patterns of equipment based on the electrical characteristics of household appliances,like the daily usage probability and the average use time of electrical appliances can be established,whose parameters are characterized by means and covariance matrices.Therefor the efficiency and accuracy of modeling can be improved significantly.On this basis,a method combining this theory with modal analysis is proposed to analyze and detect possible harmonic resonance in low voltage distribution network.The new method can quickly detect the harmonic resonance frequency and its location in distribution network,through loads probability modeling,modal analysis and other steps.Even with complex circuit and random changing of elements' parameters,the survey would be concluded with effective results by the proposed method in time.Based on analysis and detection results,some measures can be taken to improve the harmonic resonance in low voltage distribution network.The simulation results approve the method proposed in this paper is effective.