A direct grounding insulation fault detection device and method

Abstract

The invention provides a direct grounding insulation fault detection device and method with simple hardware circuit, high detection precision and no adverse effect on the DC system itself. The detection device includes a first voltage dividing circuit (110), a second voltage dividing circuit (120), a voltage equalizing circuit (130), a measured insulation resistance RX1 and a measured insulation resistance RX2, and the method is to pass the voltage equalizing circuit (130 The control of the on and off of the switch tube in ) produces two effective circuit states, and the relationship between the midpoint voltage and the bus voltage in the two states is used to realize the low-cost and high-precision detection of the direct grounding resistance. This method uses the unbalanced bridge method to give a more accurate formula for the positive and negative insulation resistance of the DC system when the insulation values ​​of the positive and negative busbars are reduced, in order to prevent the power system from being caused by DC grounding. Misoperation provides a scientific and effective detection method.

Description

technical field [0001] The invention relates to the field of power system insulation monitoring, in particular to a direct grounding insulation fault detection device and method. Background technique [0002] In the DC system, the insulation performance directly affects the reliability of the DC circuit. If there is a two-point grounding in the DC system, it may cause malfunction of the signal device, control circuit and relay protection device, causing the circuit breaker to trip, or directly causing DC The operating power supply is short-circuited, thereby causing an accident in the power system. In order to prevent the occurrence of the above situation, an insulation detection device with continuous operation and sufficient sensitivity must be installed in the DC system. [0003] Existing methods for detecting DC system insulation mainly include bridge balance method and low frequency signal injection method. The insulation monitoring device realized according to the br...

AI Technical Summary

Problems solved by technology

However, its disadvantages are: AC signal generation circuit is required, which increases the complexity of the system; the injected low-frequency AC signal increases the voltage ripple coefficient of the DC system; the monitoring results are affected by the distributed capacitance of the system; low-frequency AC signals are easily affected by various external kind of interference

[0004] To sum up, the insulation monitoring of the power system in the existing technology has the defects of complex hardware circuit, low detection accuracy, and influence on the DC system itself.

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