Device and method for monitoring neutral point earthing of secondary winding of electric power current and voltage mutual inductor

Abstract

The invention provides a device and method for monitoring the neutral point earthing of a secondary winding of an electric power current and voltage mutual inductor. The device comprises a detection amplification module, a judgement processing module, a control circuit and an alarming circuit, wherein the detection amplification module is used for detecting and amplifying a current in the neutralpoint earthing wire of the secondary winding of an electric power current and voltage mutual inductor; the judgement processing module is used for judging whether the amplified current reaches an alarming current threshold value; if the amplified current reaches the alarming current threshold value, a control circuit switch is triggered to be closed; the control circuit comprises the control circuit switch and an alarm starting unit, the control circuit is conducted when the control circuit switch is closed, and the alarm starting unit triggers an alarming circuit switch to be closed; the alarming circuit comprises the alarming circuit switch and an alarm indicator light; and when the alarming circuit switch is closed, the alarming circuit is conducted, and the alarm indicator light is lightened. According to the device and the method provided by the invention, the neutral point earthing condition of the secondary winding of an electric power current and voltage mutual inductor can bemonitored in real time, the device gives out an alarm in time if multiple-point earthing is found, and maintenance staff are notified to process the earthing condition, thereby the potential safety hazard is eliminated.

Description

technical field [0001] The invention relates to the monitoring technology of an electric power system, in particular to a monitoring device and method for neutral point grounding of a secondary winding of a power current voltage transformer. Background technique [0002] According to the relevant anti-accident measures of the power system: the neutral point of the secondary winding of the power current voltage transformer can only be grounded at one point. [0003] For the secondary circuit between several groups of voltage transformers in the same substation, the neutral point (zero-phase grounding line N600) can only be grounded at one point on the interface screen of the control room, and the high-voltage site of the switch should be disconnected, such as figure 1 shown. In the secondary circuit between several groups of voltage transformers in the same power plant and substation, the neutral point (zero-phase small busbar N600) is grounded at one point on the interface ...

AI Technical Summary

Problems solved by technology

There are many reasons for the formation of multi-point grounding, and it is difficult to detect with the naked eye, which brings safety hazards to the stability of the power system

[0007] The inventor found in the process of implementing the inventor that there is no monitoring equipment for the above-mentioned multi-point grounding problem in the power system at present, and it is difficult to find that when the system breaks down, as there are grounding points ( That is, multi-point grounding) or poor contact, the large current generated by the fault flows through the ground network of the substation. At this time, a potential difference appears between the control room and the grounding point of the high-voltage site of the switch, resulting in the potential and phase deviation of the neutral point As a result, the amplitude and phase of the protection voltage are also shifted, which eventually leads to incorrect action of the protection, and what is more serious is that the external fault causes the protection to malfunction

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