Research For The Methods Of Estimating Customers' Harmonic Emission Level At PCC

With the rapid development of scientific technology and national economics, power quality issues have gradually captured considerable attention from both utility companies and their customers. But more and more impactive loads, asymmetrical loads and nonlinear loads that bring a variety of disturbances into public network have been increasing into power system all the time, hence the bad trendency of power quality become more and more remarkable. A drastic contradiction emerges progressively. Consequently, with forming and boosting of electricity markets, the utility must meet not only the customer's requirements of increasing power quantity, but also the requirement of excellent power quality.In order to assure the quality of power supply and pertinent service level, and then ensure the normal dealings between utility companies and customers in rated limits, it is indispensable to put a penalty or a premium due to the effect of a customer, which embodies the corporate responsibility for power quality. Therefore it is the sticking point for solving the problem about separating the duty to find methods by which the customer emission level can be accessed (the voltage that a customer's harmonic current begets at the point of common coupling) more accurately.In the paper, many methods of harmonic analysis are described in detail above all, because they are the important means by which the rudimental data that various harmonic emission estimation methods require can be attained, and influence the final results. And then, the statistical methods of customer emission level are introduced in terms of whether they affect power system running or not, and their advantages and shortages are indicated. Finally, the method of estimating power customer emission level based on binary linear regression is put forward, which make it a condition that harmonic emission is steady at the point of common coupling. Combined with power system Thevenin equivalent and customer Norton equivalent, according to the principle of least squares method, the voltage that a customer'sharmonic current begets at the point of common coupling can be estimated in the light of the plural correlation of network parameters.In the end, the correctness of the method is testified by experimental simulation with Matlab at first. With the harmonic data from engineering practice, the results from the new method compare with the ones from "fluctuation method". The contrast demonstrate the effectiveness of the proposed method.