Monitoring method for grounding state of primary side of capacitor voltage transformer and system thereof

Abstract

The invention provides a monitoring method for grounding state of primary side of a capacitor voltage transformer and a system thereof. When there is a protective gap of sphere gap in the primary side of the capacitor voltage transformer, and a fundamental voltage that is output from the secondary side of the capacitor voltage transformer in the power detection appears, the capacitor voltage transformer can be determined as being input; The grounding current of the secondary side voltage circuit in the capacitor voltage transformer should be detected in the scheduled time during the input of the capacitor voltage transformer. When the fundamental voltage in the grounding current exceeds the scheduled threshold value of the current or when the high-frequency component of the currents in the grounding current exceeds the scheduled threshold of the current harmonic, the primary side of the capacitor voltage transformer can be determined as ungrounded. The measure of electric parameters in the secondary side can effectively monitor the operational state of the primary side.

Description

technical field [0001] The invention relates to the technical field of electrical equipment safety monitoring, in particular to a method and system for monitoring the primary grounding state of a capacitive voltage transformer. Background technique [0002] Capacitor Voltage Transformers (CVT, Capacitor Voltage Transformers) are divided by series capacitors, and then stepped down and isolated by an intermediate transformer. For details, please refer to figure 1 As shown, the high-voltage capacitor C1 and the medium-voltage capacitor C2 connected in series form a voltage divider. T is the intermediate transformer, L is the compensation reactor, J is the ground terminal of the capacitor, and X is the ground terminal of the reactor. F1 and F2 are overvoltage protection components. D is the damper. [0003] At present, the occupancy rate of domestic 110kV class capacitive voltage transformer is about 80%, that of 220kV class CVT is about 95%, and that of 330kV and above clas...

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Problems solved by technology

[0005] To sum up, when C2 is not grounded, the bus voltage or line voltage will all concentrate on the ungrounded terminal, resulting in continuous discharge

When the ungrounded terminal is equipped with a protective ball gap, the discharge occurs on the ball gap; when the ungrounded terminal is not equipped with a protective ball gap, or when the protective ball gap is severely burned and cannot play a protective role, the discharge may occur on the medium voltage In the transformer or medium voltage capacitor oil tank, the oil tank is burned and oil leaks. After long-term operation with damage, it can cause CVT explosion. In actual operation, there have been penetrating breakdown explosion accidents caused by non-grounding

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