Method and system for positioning short-circuit fault of intelligent distribution network

Abstract

The invention discloses a method and system for positioning short-circuit faults of an intelligent distribution network considering load influences. The method comprises the following steps of: obtaining a current phasor at each power source in the distribution network before and after the fault, and calculating a short circuit current provided by multiple power sources in the distribution networkwhen the fault occurs; obtaining synchronous current data and voltage data of each end point of each section before and after the fault, and calculating a current level of the internal load of each section; calculating a current phasor characteristic value of each section when the fault occurs according to the current level of the internal load of each section and the short circuit current when the fault occurs; collecting the current phasor characteristic values of each section under multiple time scales, and constructing a current space-time characteristic matrix of each section; calculating a norm value of the current space-time characteristic matrix of each section, and storing to a characteristic value unit; and traversing the characteristic value unit to find a minimum norm value, and the section corresponding to the minimum norm value is a fault section.

Description

technical field [0001] The present disclosure relates to the field of fault location, in particular to a method and system for short-circuit fault location of an intelligent distribution network considering the influence of loads and branch lines. Background technique [0002] The distribution network is the last station of power transmission, and it is an important link to receive renewable energy, improve the operating efficiency of the power system, and deliver power to users safely and efficiently. When a short-circuit fault occurs in the distribution network, quickly and accurately locate the fault section is the key technology to isolate the fault section and restore the power supply in the non-fault area. With the massive access of distributed generation (Distributed Generation, DG), limited by power electronic devices, the short-circuit current capacity of DG is relatively small, which leads to the fact that the calculation of fault characteristics cannot ignore the ...

AI Technical Summary

Problems solved by technology

Among them, the matrix method has weak fault tolerance and is prone to misjudgments and missed judgments; although the positioning method based on artificial intelligence has good fault tolerance, it generally has shortcomings such as relatively complicated model construction, low positioning efficiency, and incomplete models.

The eigenvalue comparison method is based on its accurate calculation of eigenvalues ​​and obvious judgment features. It has received widespread attention in recent years, but there are still the following problems: the short-circuit current capacity of the DG side is small, and the influence of load on the fault criterion cannot be ignored, and the transition resistance during short-circuit The existence of DG exacerbates the impact of load; under the connection of DG high penetration rate, the influence of time-varying DG output on fault eigenvalues ​​is not considered

[0006] (1) The influence of load on the criterion when a fault occurs

In the distribution network short-circuit fault location algorithm, it is often considered that the short-circuit current is far greater than the load current when the fault occurs, but in the actual operating environment, only inverter DGs are connected to the grid at the end of the line. Influenced by the device, the DG short-circuit current is only 1.2 to 2 times the rated current, which makes it impossible to ignore the influence of the load current when analyzing the back-side fault current in the section positioning algorithm, resulting in missed judgments; in addition, affected by natural conditions, DG switching operations are frequent, resulting in complex and changeable eigenvalues ​​of the load-containing section, which also has a great impact on the accuracy of the fault location algorithm; due to the slow development of my country's distribution network, it is impossible to balance faults in each section of the line like the transmission network. The installation of measuring devices has caused great difficulty in fault location;

[0007] (2) Different types of sections lack a unified fault analysis method

[0008] (3) Short-circuit fault location is prone to misjudgment

In the traditional distribution network short-circuit fault location process, due to the accuracy of the measuring device and the large disturbance of the load and DG, it is very easy to misjudge the fault;

[0009] (4) There is a contradiction between the sensitivity of the transition resistance and the accuracy of the algorithm in the current positioning algorithm, that is, the lower the threshold of the starting criterion is set, the algorithm can detect the short-circuit fault with the greater the transition resistance, but it is affected by the DG , electric vehicles, etc., the greater the probability of misjudgment

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