Study On The Value Of Overhead Ground Wire Shunt Coefifcient When Substations Are Shotred

The grounding system of the power plant or substation is to maintain the safe andstable operation of power system, and reliable operation of the power system andelectrical equipment safety guarantee. There have been happened many accidents inthe system of our country because of the grounding system of the power plant orsubstation were not meet the requirement. We need to determine the roundingresistance, step voltage and equipment contact voltage multiple target value of thepower plant or substation when we design or modification the grounding system ofthe power plant or substation. So, at present, for grounding system in substationgrounding design, there is a big difficult problem is the ground target identification,because of substation grounding device, grounding resistance, step voltage size,equipment contact voltage by grounding short current in earth decision. In current byoverhead ground wire shunt coefficient, to accurately determine the groundingresistance in substation is the target value, must accurate calculation of overheadground wire shunt coefficient. But at present the design manual calculation methodhas more parameters to value. Therefore, the substation grounding short circuitoverhead ground wire shunt coefficient is very necessary to study.This paper analyzes the current calculation of overhead ground wire shuntcoefficient used in some methods in calculating the problem that exists in the process,the method in engineering are actually related parameter to value or parameter isconsidered not comprehensive conclusion. Therefore, this paper comprehensivelyconsidering station fault and station fault two situations when the fault currentdistribution, are established in power plant or substation and station fault currentdistribution model. Through MATLAB simulation software to build a220kVsystemsimulation model, on effects of various overhead ground wire shunt factor simulationanalysis, obtained each factors on overhead ground wire shunt effect law. In thesimulation the influence law on the basis of the establishment of the power plant,substation fault and station fault overhead ground wire shunt circuit model and thesimplified reasonably, through the simplified circuit model, this paper uses the loopcurrent method were deduced, and substation fault overhead wire shunt coefficientcalculation formula, because the two formula considers the influence of zero sequencecurrent, thus the calculation result and the actual situation of power system moreconsistent.At present, the computer in the power system has also been widely use, therefore,this paper uses computer software programming to calculation the shunt coefficient,and proves the formula of accuracy. The shunt coefficient calculation without havingto install software, the interface is clear and easy to understand, easy operation, highpracticability, through actual correction can be applied.