Study On The Influence Of Zero Sequence Mutual Inductance Of 110kV Transmission Line On Relay Protection Setting

With the rapid development of social economy and land resources become increasingly tense,110 kV multi circuit transmission lines on same tower(with the laying)has become a common choice,but zero sequence mutual multi circuit directly affects the relay protection method based on zero sequence.In order to prevent the relay protection beyond the action or reject action,the current research mostly used the method to eliminate the zero sequence mutual inductance,due to the existence of complex wiring,operation and maintenance problems such as cumbersome method to eliminate zero sequence mutual inductance in 110 kV transmission line,numerous and complex,a short time is difficult to achieve.This paper adopts a new research idea of zero sequence mutual inductance tuning effect of 110 kV transmission line relay protection,through the qualitative analysis of zero sequence relay protection setting of tie line,the quantitative calculation to the setting value of zero sequence mutual inductance error caused by relay protection,the error and the protection setting principle of current relay,if the error in the scope of the current protective relaying principle within the protection setting principle can also use relay is the current application,otherwise setting risk,need to take the line parameters measured value and adjust sensitive coefficient,reliable adjustment coefficient of control measures.It is of practical significance to prevent and protect the correct action,reduce the field relay protection setting,the actual workload of the line parameters and so on.The main contents of this paper include:1)based on the line mode of 110 kV power network in Dongguan area,combined with the protection scheme and setting principle,the existence form of zero sequence mutual inductance of 110 kV transmission line is studied and analyzed;2)on line terminal(contact line and transfer line),double loop(including power line and non power line),single line power plant and other three kinds of typical connection modes,the qualitative analysis of the impact of setting of zero sequence mutual inductance of grounding fault protection,quantitative calculation to the setting value of zero sequence mutual inductance error band to relay protection,and derived in the compensation of zero sequence mutual inductance tuning range when the percentage error calculation formula of measuring impedance protection in practice and its theoretical value.3)to Dongguan power grid power plant double grid lines 110 kV line,110 k V a Dongtang B line as a specific Dongtang verification object by setting calculation software RelayCAC,the practical example calculation for zero sequence mutual inductance of grounding distance protection,zero sequence current protection setting value of the error at the same time,the evaluation result of zero sequence mutual inductance of grounding distance protection zero sequence current protection incorrect action setting risk,and put forward the corresponding control measures.