Research On Detection And Localization Of Harmonic Sources

With the rapid growth of economics, power quality issue has increasingly captured considerable attention from both utility companies and their customers. On one hand, with the increase of nonlinear loads, there are more and more factors that will bring challenge on the power quality, for instance the progress on power electronics appliance and its implementation in industry and transportation companies. On the other hand, people have higher request on the power quality and reliability of power system because more complex, rigid and power quality-sensitive appliance is widely used.In order to assure the quality of power supply, and 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. There for it is the sticking point for solving the problem about separating the duty to find methods of assessing the harmonic emission level. Primarily, the available methods for measuring or calculating harmonic impedances can be divided into two classes, one is invasive and the order is non-invasive. The former is based on injecting (inter)harmonic currents into or switching some branch at the PCC. These methods may cause harmful influences on the operation of power system. The latter is to use pre-existing harmonic sources or measured data to assess harmonic impedance and harmonic emission level.In this paper, many methods of harmonic analysis are described in detail above all, including detection and localization of harmonic sources, assessing the harmonic emission level, etc. 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 assessing the harmonic emission level base on robust regression method, which make it a condition that system harmonic is steady. Combined with power system Thevenin equivalent and customer Norton equivalent, according to the principle of robust regression to solve regression coefficient. Then the harmonic impedance of system can be got. Consequently the harmonic emission level of customer can be calculated. Through the simulation analysis of laboratorial circuit and the analytic result of practical engineering road-resting data, the method proved its validity.