Method for detecting continuous high-impedance-grounded fault of medium-voltage distribution system by current information

Abstract

The invention relates to a method for detecting continuous high-impedance-grounded fault of a medium-voltage distribution system by current information, and belongs to the field of an emergency protection circuit device. The method comprises the steps that residual current of each path of outlet wire on the same bus is collected in real time; the residual current is subjected to harmonic analysis; the amplitude value and the phase position of triple harmonics and fundamental waves of the residual current are extracted; the phase position difference and the amplitude value proportion of the triple harmonics and the fundamental waves of the residual current of each path of outlet wire are compared; the comparison with the corresponding preset detecting threshold value is carried out, and when the detecting threshold value condition is met, 'condition satisfaction' flag bits are set, the flag bits are subjected to timing and counting, timing and counting results are classified, corresponding fault events are reported, and corresponding processing program is started. The method has the advantages that the action threshold value of set values of the ground protection action can be further reduced, the high-impedance-grounded fault can be more flexibly detected, and fault circuits are cut in time. The method can be widely applied to the fields of relay protection and high-impedance-grounded fault detection of the medium-voltage distribution system with a neutral point in effective grounding.

Description

technical field [0001] The invention belongs to the field of emergency protection circuit devices, in particular to a detection / protection method for high-resistance grounding faults in cable or line systems. Background technique [0002] In my country's power system, the AC voltage level with a nominal voltage of 1kV and below is defined as low voltage, the AC voltage level with a nominal voltage of 1kV and below 330kV is defined as high voltage, and the AC voltage level with a nominal voltage of 330kV and above The voltage level is defined as ultra-high voltage, and the AC voltage level with a nominal voltage of 1000kV and above is defined as ultra-high voltage; the standard document of the Institute of Electrical and Electronic Engineers (IEEE) defines the voltage from 2.4kV to 69kV The level is called medium voltage; in the normative documents of my country's State Grid Corporation (State Grid), the voltage level from 1kV to 20kV is called medium voltage. [0003] The gro...

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Problems solved by technology

However, the high-resistance ground fault that is difficult to detect by tr

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