Method and device for judging disconnection of secondary circuit of rotor grounding protection
A rotor grounding and secondary circuit technology, which is applied to emergency protection circuit devices, circuit devices, parts of emergency protection devices, etc., can solve the problems of large grounding resistance, rotor grounding protection refusal to operate, etc., and achieve the effect of preventing refusal
Active Publication Date: 2020-03-20
NR ELECTRIC CO LTD +1
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Problems solved by technology
If the generator rotor has a ground fault after the secondary circuit is disconnected, the ground resistance calculated by the protection device will be too large, resulting in the possibility that the protection device will refuse to operate for the rotor ground protection
Conventional rotor ground protection does not take this situation into consideration, so it is necessary to study a method and device for monitoring the disconnection of the secondary circuit of the rotor ground protection. After the circuit is disconnected, an early warning is issued to remind the user to repair and prevent the secondary circuit of the rotor from being disconnected. The failure of the rotor ground protection protection caused by the fault
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Embodiment Construction
[0039] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.
[0040] Theoretical analysis shows that the rotor circuit circulation is composed of two parts: 1. The ratio of the excitation circuit voltage to the circuit impedance; 2. The charging and discharging current of the ground capacitor. Since the ground capacitance of the generator rotor circuit is not large, the charge and discharge current of the ground capacitance is not large, and the impedance of the rotor circuit is a fixed value. The greater the voltage of the excitation circuit, the greater the corresponding loop current. When the loop is disconnected, the loop impedance increases significantly, and the monitored loop current decreases significantly, which is basically composed of the charge and discharge current of the ground capacitor. Monitoring of rotor secondary circuit disconnection. In addition, there are two situations that nee...
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The invention discloses a loop current monitoring-based line breakage judgment method and device of a rotor grounding protection secondary loop. The method comprises the steps of measuring a voltage of a power generator rotor and a ring current of a rotor grounding loop by a protection device, calculating grounding resistor of the power generator rotor, taking the situation that the ring current of the rotor grounding loop is smaller than an action threshold as a main criterion, taking the situation that the rotor voltage and the rotor grounding resistance are larger than respective action threshold as an auxiliary criterion, judging that the rotor grounding protection secondary loop is broken when the main criterion and the auxiliary criterion both are conformed, and acting to warn by protection after delaying time t. By the method, a line breakage fault of the rotor secondary loop can be identified, a user is reminded of maintenance, and the situation that the rotor grounding protection rejects to perform brought by the line breakage fault of the rotor secondary loop is prevented.
Description
technical field [0001] The invention belongs to the field of relay protection of electric power systems, and in particular relates to a method and a device for judging disconnection of a secondary circuit of rotor grounding protection. Background technique [0002] Rotor ground faults are common in generator faults, so the reliability of rotor ground protection becomes very important. Injection rotor ground protection and ping-pong rotor ground protection are the two most widely used rotor ground protection principles in the field. The secondary circuits of the two grounding protection principles are connected in series with high-power resistors. Due to the high excitation voltage of the rotor circuit and the large harmonic content, the secondary circuit of the rotor may be damaged and disconnected after long-term operation. It is common for power resistors to be damaged. If the generator rotor has a ground fault after the secondary circuit is disconnected, the ground resis...
Claims
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IPC IPC(8): H02H7/08H02H1/00
CPCH02H1/0007H02H7/08
Inventor 钟守平陈佳胜陈俊王光李华忠张琦雪王凯郭自刚季遥遥徐天乐王洪林
Owner NR ELECTRIC CO LTD