Failure Analysis And Research Of High-voltage Power Capacitor

The basic function of power system is to supply the users electricity which is the highly quality, safety and economy as much as possible.The safe and stable operation of power system depends on the reliable operation of its each part.Power capacitor which can alter reactive power flow and power factor to compensate reactive power is the basic equipment in substation.Because the power capacitor is operated frequently, so it plays an important role in the operation of power grids. Capacitor's failure in substation will be a serious threat to the stability of power grid's operation and user's production and living.So to investigate and analyze the reliability, the failure mode and mechanism of capacitor from the perspective of user and production is very important.In this paper, the fault reasons and protection scheme of 1 OkV shunt capacitors bank in substation is researched to enhance the reliability of the power capacitor.This article studies on two operation factors of grid which lead to the failure of the capacitor:transient over voltage and harmonic current.Firstly simulation model is built upon making lOkv shunt capacitors of a certain substation as the analysis platform and combining with capacitor bank's operation mode and parameters of substation.On the basis of theoretically analyzing the process of capacitor's switching, I will use alternative transient program software (ATP) to simulate the process of capacitor's switching. Transient over voltage, over current waveform presenting when capacitor bank is switching is given,and I will analyze its change rule under different factors changing.Then on the basis of the practical situation in this substation,the equivalent harmonic analysis model will be established.The harmonic equivalent circuit will be analyzed theoretically, and study the laws of every harmonic which causes harmonic current harmonic amplification.The influence of serial reactor to the harmonic amplification will be discussed, and the harmonic parameters test results of this substation is given.On the basis of analyzing what cause the failure, this article will design and analyze the three methods of protection:(l)Using adjustable series reactor.This paper will analyze the effect of series reactor in the transient process of switching operations and the process of harmonic amplification.And I will puts forward the solution of connecting with adjustable reactor which will solute problems of the reactor parameters configuration.(2) Using thyristor to switch capacitor bank.In this paper, the program of using thyristor to switch capacitor for reactive power compensation will be presented. It hopes that there will be no transient cutting process, if it meets the conditions of the switching conditions.And its feasibility will be validated by MATLAB simulation model.