The Research On Characteristic Quantities And Overvoltage Protection Of Capacitor Breakdown In A Shunt Capacitor Bank

Power capacitors are the basic components of reactive power compensation device in the power system. Capacitor's serious damage caused by Manufacturing reasons or the improper design, operation and maintenance, will bring great losses to the grid. Therefore, it is necessary to research on the characteristics of and performance of the capacitor's damage inorder to perfect protection of capacitors.In this paper, the capacitor fault conditions of Dongguan Power Supply Bureau of Guangdong Power Grid in 2009 are used as a templet and used for statistics and analysis.Based on the detailed analysis and statstics of examples, this paper gives a research of the causes of leading to reactive power compensation capacitors faults. Also, according to the analysis of various fault type, failure rate of various factories and various typical faults of capacitors in actual use, this paper gives some measures to prevent capacitor fault. At the same time, the paper uses EMTP simulation software to do the simulation test on the internal capacitance components of parallel capacitors breakdown for a string, which is used to determine the waveforms of the capacitor breakdown current simulation and of the fault or non-fault phase voltage simulation. Then the characteristic quantity of capacitor breakdown is analyzed.It is deduced the changing rule of the neutral-line unbalance current using the varied-capacitance of the capacitor bank. With the simulation results, the protection range and setting value of the neutral-line unbalance current are given to provide the effective and quick protection of the shunt capacitor bank.Through various analysis,developing measures to improve the operating efficiency and service life of capacitors. The reliability of power system can be improved, too.