Reseatch On Determining Harmonice Responsibility Of Multiple Harmonice Sources In Distribution Network

With the wide adoption of nonlinear components, the harmonic problem of power system has become increasingly serious. Harmonic affects the safe and economic operation of power system, and it is one of the main factors that influence the power quality and reliability. Accurate assessment of harmonic pollution level and harmonic responsibility is the important premise of effective governance of harmonic and power supply of high quality.This paper firstly studies the assessment of harmonic pollution level. The harmonic pollution level comprehensive evaluation index system is set up considering the single harmonic pollution level evaluation index problem. The index weight is calculated with the combination of subjective and objective method, where the subjective weight is obtained by using the analytic hierarchy process (AHP) and the objective weight is calculated by using the entropy weight method. The subjective weight is revised with objective weight for the final harmonic pollution index weight, and then the harmonic pollution level comprehensive evaluation has to be realized. The monitoring data from a 10kV substation bus bar is used to assess the harmonic pollution level, the result shows that the proposed approach can accurately calculate the harmonic pollution level and it lays the foundation for assessing the harmonic responsibility in the subsequent chapters.Secondly, in order to distinguish the harmonic responsibility of power system and customers and solve the contradiction, this paper studies the evaluation individual harmonic responsibility of multiple harmonic sources ignoring the fluctuation of the background harmonic voltage. The traditional harmonic responsibility method is improved. The harmonic contribution is evaluated with nonlinear method. Derived formula and objective function are solved by particle optimization. Finally, the harmonic responsibility of multiple harmonic sources is evaluated. The proposed method does not need to constrain harmonic current, and it is more applicable compared with traditional method. The simulation was conducted under four different conditions, respectively. And the measured data from a 10kV substation bus in Hefei is used to verify the validity of the method.Finally, a new method is proposed to evaluate the individual harmonic responsibility of multiple harmonic sources considering the fluctuation of background harmonic voltage. The system harmonic impedance is estimated by the dominant fluctuation filtering principle. And the background harmonic voltage is divided into different data segment by mean shift algorithm according to the fluctuation of the background harmonic voltage. The harmonic responsibility of each segment is estimated by partial least squares method. And its harmonic weighted sum is calculated to get the final harmonic responsibility. The proposed method is tested on a system with three harmonic sources and the IEEE 13-bus test system. The result shows that, compared with least squares method and robust regression method, the proposed approach can distinguish the harmonic responsibilities effectively due to all main harmonic sources to the concerned buses.This paper studies the harmonic evaluation and harmonic responsibility methods. The harmonic comprehensive evaluation is achieved based on the formation of evaluation index set. Moreover, the harmonic responsibility is established when the harmonic pollution exceeds the limit, which provides the basis of harmonic elimination.