Short-time controllable reactor compensation method

Abstract

The invention relates to a short-time controllable reactor compensation method, belonging to the field of emergency protection devices. The compensation method comprises the steps that when a ground fault occurs in a power distribution network, inductive current which is needed to be compensated is calculated according to measured grid capacitive current value, then a controllable reactor is controlled to output compensation current; for a common transient ground fault, after the inductive current is compensated, the ground fault is automatically eliminated and a normal state is restored; and as to the situation that the ground fault still exists after preset time after the controllable reactor compensates the current, a permanent ground fault is deemed to occur in a system, a high-voltage switch is automatically turned off after the time duration of grounding exceeds the preset time, and a small resistance is switched on to enable feeder line protection to act to cut off a faulty line by virtue of switch trip. By adopting a neutral point joint grounding mode, the joint use of the controllable reactor and the small resistor is realized, the duration of the ground fault is judged to distinguish the transient ground fault from the permanent ground fault, different countermeasures are adopted and so the goal of improving power supply safety and reliability is achieved.

Description

technical field [0001] The invention belongs to the field of substation emergency protection devices, and in particular relates to a processing method for substation grounding faults. Background technique [0002] At present, there are mainly the following methods for the neutral point grounding point of the distribution network with a voltage level of 35kV and below in the power system: 1. The neutral point is not grounded; 2. The neutral point is grounded through a resistor (mainly the small resistance grounding method) ; Third, the resonance grounding method (the neutral point is grounded through the arc suppression coil). [0003] In the neutral point ungrounded system, when a phase fault occurs, the power supply of the receivers connected to the phase-to-phase voltage has not been damaged, and they can continue to operate, but at this time the non-faulted phase voltage rises, and the weak point of the insulation is very It may be broken down, causing a phase-to-ground ...

AI Technical Summary

Problems solved by technology

[0007] The traditional "arc suppressing coil grounding" method can automatically eliminate instantaneous single-phase ground faults, which has the advantages of reducing the number of trips and the ground fault current. However, since non-instantaneous single-phase ground faults cannot be eliminated, the entire power distribution system has Long-term (2 hours) power frequency overvoltage (line voltage), so the insulation level of equipment is high, which is not good for power distribution system equipment (especially for some imported equipment, such as cables); at the same time, single-phase grounding The long-term existence of faults is not conducive to equipment and personal safety

Moreover, the fault line selection in the traditional "arc suppression coil grounding" system has always been a technical problem, and the actual line selection accuracy is very low

[0008] The "low-resistance grounding" method can avoid the problem of long-term power frequency overvoltage in the power distribution system, and has relatively low requirements for equipment insulation. power supply reliability

[0009] Therefore, these two grounding methods have their own advantages and disadvantages, and can only be applied to certain conditions. It is urgent to seek a more complete new grounding method

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