Identification Of Harmonic Source In Substation

Due to the widespread of nonlinear devices in power system, the harm of harmonic in power system is becoming more and more serious,but the demand of user for power quality is getting higher and higher. The international usually adopts "reward and punishment scheme to the users who exceed the limit, China put forward the harmonic management that "who pollution, who governance". In order to control harmonic effectively, and precisely divide the responsibility of the harmonic, identification of harmonic source has become an important issue of harmonic governance.The problem of harmonic source identification is mainly for distributed bus system at present, the system takes the buses of the substation as the nodes,the results of harmonic source identification can only recognize the level of substation,but the source of substation harmonic is located in which feeder and analyzing component of each harmonic source are still difficult points. Aiming at the substation's multi-feeder system, this paper analyzed the electrical characteristics of substation harmonic source and identified harmonic source in the substation feeder layer by using broad-sense harmonic theory and independent component analysis(ICA).According to the characteristics of the substation bus voltage distortion and the coupling property of feeder harmonic currents and so on, it took bus voltage as a orthogonal basis and completed the orthogonal decomposition to feeder current based on the generalized harmonic theory, from which it can analyze the relationship between the signals of bus voltage and each feeder current, calculated nonlinearity of each feeder load, judged the location of harmonic source, and figured out the responsible of harmonic clear.It is difficult to obtain the parameters of the substation system and the harmonic source of blind source etc. According to the theory of multi-port network, the substation can be equal an n port network, which is corresponding to multi-harmonic source model of substations to analyze the implication of parameters in the n port network. It can get harmonic current signal of each harmonic source in substation by using independent component analysis(ICA) through pretreatment of load voltage signal and state estimation equation measure separation degree of each component by negentropy, and it completes the analysis of substation harmonic component.The identification of substation harmonic source based on broad-sense harmonic theory and independent component analysis(ICA) not only can accurately predicate the number and the location of substation harmonic source, but also can obtain the components of harmonic sources. The simulation results showed the feasibility and accuracy of the proposed method for harmonic source identification in multi-feeder substation system.