The Study On Indirect Methods To Measure Capacitance Current In Distribution Networks

The methods for measuring capacitance phase-to-earth current in distribution networks has been analyzed in detail in this paper, and many simulative experiments are completed. Their advantages and limitations are indicated in this paper. The method to measure capacitance current based on injecting signals method is studied. On the basis of previous methods such as three-frequency method; two-frequency method and sweeping frequency method, the method to measure ungrounded distribution networks is advanced. An improved method is putted forward. In this method, current signals with the same amplitude and different frequency are injected into the secondary winds of PT, and relation equations can be founded. Capacitance current can be got by these equations. According to the principle analysis and the results of simulative experiment, this new method is better than previous methods. It has the advantages such as convenient operation and being accurate. Based on the improved method, the hardware and the software of measurement device are designed by the chip C8051F021.