Medium-voltage power distribution network three-phase ground capacitance unbalance suppression system and method

Abstract

The invention provides a medium-voltage power distribution network three-phase ground capacitance unbalance suppression system and method. The system comprises a plurality of compensation capacitors and a scheduling master station, wherein the compensation capacitors are divided into bus compensation capacitors and feeder compensation capacitors, each phase of a power distribution network bus is connected with one end of the corresponding bus compensation capacitor, and/or each phase of the power distribution network feeder is connected with one end of the corresponding feeder compensation capacitor, and the other end of the feeder compensation capacitor is grounded; each compensation capacitor is provided with an independent fling-cut switch; and the dispatching master station remotely controls split-phase switching of the three-phase compensation capacitor to realize three-phase ground capacitance unbalance suppression of the medium-voltage power distribution network.

Description

technical field [0001] The disclosure belongs to the technical field of ground-to-ground capacitance unbalance suppression, and in particular relates to a three-phase-to-ground capacitance unbalance suppression system and method for a medium-voltage distribution network. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] The medium-voltage distribution network (10kV-35kV) widely adopts the neutral point grounding system through the arc suppressing coil. Due to insufficient line commutation and other reasons, there will be an imbalance in the equivalent capacitance of the distribution network when it is in normal operation. . [0004] The inventors have found that the unbalanced capacitance to ground will cause the following problems: [0005] (1) The arc suppression coil at the neutral point flows current, and the neutral point voltage of ...

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Problems solved by technology

[0006] (2) The long-term rise of the neutral point voltage will not only bring additional loss to the transformer, but also weaken the compensation effect of the arc suppression coil on the fault current, and deepen the harm of the ground fault

[0007] Aiming at the problem of neutral point voltage rise caused by unbalanced three-phase-to-ground capacitance of the line, the existing methods mainly adopt the following scheme. method to eliminate the three-phase-to-ground capacitance imbalance and the neutral point voltage rise caused by it, but this method is difficult to apply to lines that have been put into operation; Zhang Zhaonan et al. In "Analysis and Treatment of Unbalance", a large capacitor is connected between the neutral point and the ground to suppress the neutral point voltage rise caused by the unbalanced capacitance of the three phases to the ground, but this method needs to add a device, and it will affect the arc suppression The compensation accuracy of the coil; Li Jiazheng et al. In the literature "Distribution Network Unbalanced Overvoltage Suppression Method Based on Zero-Sequence Voltage Regulation", an inverter power supply is connected between the neutral point and the ground, and the output voltage is controlled to offset The neutral point voltage rise caused by the unbalanced capacitance of the three phases of the line, however, this method needs to add a device, the implementation is complicated and the cost is high

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