Power cable intersect cross connection grounding system grounding current monitoring and evaluating method

Abstract

The present invention provides a power cable intersect cross connection grounding system grounding current monitoring and evaluating method which is implemented by a power cable grounding current monitoring system. The method comprises the steps of calculating a cable sheath self-impedance, calculating a sheath induction voltage caused by a to-be-tested cable wire core load current, calculating a cable sheath induction voltage caused by a to-be-tested cable sheath grounding current and a large ground leakage current, calculating an induction current of a to-be-tested cable, calculating a cable capacitive current, predicting a grounding current fluctuation value caused by the load change, predicting the grounding current fluctuation caused by the load change, analyzing and determining the current condition of a power cable intersect cross connection grounding system cable sheath, etc. The power cable intersect cross connection grounding system grounding current monitoring and evaluating method of the present invention is different from a method of analyzing and calculating a grounding current from a circuit model purely, introduces the ideas of prediction, analysis and cable parameter characteristic calculation, enables the grounding current monitoring and evaluating accuracy of a power cable intersect cross connection grounding system to be improved effectively, and provides a more effective analysis method for cable external insulation state evaluation.

Description

technical field [0001] The invention relates to the field of power grid safety monitoring and evaluation, in particular to a grounding current calculation and analysis method for a power cable cross-connected grounding system. Background technique [0002] With the rapid development of China's economy and the continuous improvement of the level of urban modernization, power cables, as important equipment in urban power grids, develop extremely fast, and urban power cables are usually laid out in the ground. One of the reasons for the failure of urban cables in actual operation is the fault of the grounding system of the power cable, which accounts for 21% of the cable faults. The outer sheath of the power cable is easily damaged by external force, chemical corrosion, and lightning overvoltage during use. or system overvoltage, etc., the insulation of the sheath is damaged, resulting in grounding at one or more points, thereby destroying the grounding system of the metal shea...

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Problems solved by technology

[0004] The purpose of the present invention is to propose an effective monitoring and evaluation method for the grounding current of the power cable cross-connection grounding system, so as to solve the problem of lack of guidance and limitation on the grounding current value of the monitored power cable cross-connection grounding system in the prior art problems, improve the effectiveness of cable insulation status assessment

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