A phase selection method for single-phase-to-ground faults in distribution network with asymmetric parameters

Abstract

The present invention proposes a phase selection method for a single-phase-to-ground fault of a distribution network with asymmetric parameters, which includes the following steps: Step S1: when the distribution network is in normal operation, measure the zero-sequence unbalanced voltage caused by the asymmetry of the three-phase-to-ground parameters of the line, And inject current into the distribution network through the flexible arc suppression device attached to the distribution network bus, measure the zero-sequence voltage at the bus, and calculate the equivalent ground admittance of the distribution network; step S2: a single-phase occurrence in the distribution network In the event of a ground fault, the flexible arc suppression device is used to inject currents with different amplitudes into the distribution network twice, measure the zero-sequence voltage at the busbar, and use the injected current and the zero-sequence voltage of the busbar to calculate the voltage amplitude of the equivalent voltage source of the fault circuit. value and phase; step S3: compare the voltage phase of the equivalent voltage source of the fault circuit with the phase of the negative value of the three-phase power supply voltage, and the phase with similar phase is judged as the fault phase; the present invention can accurately and quickly select the fault phase, The compensation current is injected accurately to ensure that the fault arc can be extinguished reliably.

Description

technical field [0001] The invention relates to the technical field of distribution network safety design, in particular to a phase selection method for a single-phase grounding fault of a parameter asymmetric distribution network. Background technique [0002] The complex operating environment of the distribution network is prone to cause single-phase grounding faults. With the expansion of the distribution network and the widespread use of power electronic equipment and cable lines, the active and harmonic components of single-phase ground fault currents increase. Since the traditional arc suppression coil can only compensate the reactive power component in the single-phase grounding fault current, there are still large active power and harmonic components in the fault residual current after compensation, which makes the arc easy to reignite and reduces the power distribution network. Power supply reliability. [0003] The existing flexible arc suppression devices can co...

AI Technical Summary

Problems solved by technology

However, it is necessary to correctly judge the fault phase before arc suppression. If the phase selection is wrong, it is easy to cause a two-phase ground short circuit, which will further increase the fault current.

Not only can it not achieve the purpose of arc suppression, but it will also cause the power equipment to heat up, cause the insulation of the equipment to age, and even lead to accidents such as fire

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