A method for judging weak branches in distribution network considering single-phase disconnection resonance overvoltage

Abstract

The invention discloses a weak branch judgment method considering single-phase broken-line resonant overvoltage for a power distribution network. The weak branch judgment method is characterized by comprising the following steps of 1, acquiring a network parameter, a running parameter and a load parameter of a target power distribution network, simulating a single-phase broken-line fault scene occurred in a circuit, and determining parameter distribution before and after a circuit fault point according to load and compensation capacitor configuration conditions after a broken-line point; 2, respectively calculating an impact voltage factor and an impact current factor of a circuit i; 3, calculating a transformer excitation impact current factor of the circuit i; and 4, estimating vulnerability of the single-phase broken-line resonant overvoltage of the circuit by calculating fragility of a single-phase broken-line resonant overvoltage structure of the circuit, and determining a weak branch according to an estimation result. According to the method, the physical characteristic of the power distribution network is used as a basis, the network parameter and the load and compensation capacitor configuration conditions after the broken-line point are comprehensively considered, the vulnerability of the single-phase broken-line resonant overvoltage of each circuit is estimated, so that the weak branch existing in the power distribution network is found out.

Description

technical field [0001] The invention relates to a method for judging a weak branch of a power system, in particular to a method for judging a weak branch of a distribution network that takes into account the resonance overvoltage of a single-phase disconnection. Background technique [0002] The disconnection fault is a common fault that occurs on the distribution network line, which may be caused by the disconnection of the wire, the partial-phase action of the circuit breaker, the severe non-periodic operation, and the partial-phase fusing of the fuse. Among all the disconnection faults, the single-phase disconnection fault has the highest probability. [0003] The disconnection resonance overvoltage is mainly due to the system inrush current flowing into the no-load or light-load distribution transformer when the disconnection occurs, resulting in the magnetic saturation of the transformer, the reduction of the excitation inductance, and the matching with the system-to-gr...

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Problems solved by technology

[0004] Most of the existing methods for judging weak branches of distribution networks are based on complex network models, using methods such as removal strategies and power flow calculations to find weak points in the system, and assessing the degree of harm after a line failure from the perspective of risk theory, it is very difficult Less consideration is given to the impact of line capacitance to ground and asymmetric faults on line vulnerability, but this kind of fault is precisely the more common fault form in distribution networks

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