Power grid fault impact strength quantitative index analysis method based on EWM

Abstract

The invention discloses a power grid fault impact strength quantitative index analysis method based on EWM. The method comprises the following steps: establishing a sub-index model according to power grid fault transient data, solving a voltage drop area, a voltage drop amplitude and a voltage change rate of a target node, establishing a decision matrix and performing utility type normalization processing on matrix data, and then according to EWM, calculating characteristic proportions of evaluation objects, calculating entropy values of indexes, calculating information redundancy, calculating weights of all the indexes, and finally calculating a comprehensive score of each evaluation object, namely a value of a quantitative index. The method is simple in principle, rapid in calculation, good in performance, capable of achieving quantitative expression of the system node voltage stability after the power system is subjected to fault impact in a short time, good in use value, and capable of enhancing manual judgment of the severity of the system fault to a certain extent through data visualization, and a control strategy is adopted to prevent further expansion of the fault.

Description

technical field [0001] The invention belongs to the field of power grid fault analysis, and specifically relates to an EWM-based quantitative index of power grid fault impact intensity and an analysis method thereof. Background technique [0002] With the rapid development of the power industry and the continuous expansion of the scale of the receiving end system, the main contradiction in the safe and stable operation of the power grid has transformed from the problem of power angle stability to the problem of voltage stability. The focus of voltage stability research is the mechanism of voltage collapse and the establishment of voltage stability indicators. The starting point of voltage stability index research is to provide voltage stability reference information for dispatching operators to prevent voltage collapse accidents. Therefore, it is of great significance to accurately understand the nature of voltage stability, correctly establish a mathematical model for volt...

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Problems solved by technology

[0006] 1) In the calculation process of the system voltage stability index based on the static method, it is necessary to track and judge the singularity of the Jacobian matrix of the power flow or equilibrium point equation of the entire system, which involves high-dimensional matrix inversion, which requires a large amount of calculation, and increases with the number of system nodes. The calculation time is greatly increased, making it difficult to apply online

[0007] 2) On-line monitoring of system voltage stability based on branch measurement information Assume that at a certain time section, the branch of the system can be regarded as an infinite power supply supplying power to the load. When the system voltage is critically stable, the power of the branch reaches the limit , this method only needs to search the key branches of the system, which can avoid the identification and tracking of Thevenin parameters, but the theoretical foundation is weak, and it is only effective in special cases

[0008] 3) The theoretical basis of on-line monitoring of system voltage stability based on node measurement information is that when the system voltage is critically stable, the power consumed by the load node is the largest. At this time, the impedance modulus of the load node is equal to the Thevenin equivalent impedance modulus, and the theoretical foundation is solid. , but this method has the problem of equivalent parameter drift in the process of Thevenin equivalent, which leads to large calculation errors

At the same time, it should be pointed out that this evaluation index is only used to evaluate whether the system is stable after a fault, but it cannot quantitatively give the stability of the voltage.

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