Distribution network static voltage stability probability assessment method based on two-point estimating method

Abstract

The invention relates to a distribution network static voltage stability probability assessment method based on a two-point estimating method. The distribution network static voltage stability probability assessment method comprises the following steps that firstly, a random output model of a distributed power source is established, the statistical property of random variables in the model is determined, and the two-point estimating method is adopted to obtain calculation sample values and the weight of samples; secondly, on the basis of all the samples, the continuation power flow method is adopted to obtain corresponding static voltage stability thresholds and critical load margins, and the statistical property values of the voltage stability thresholds and the critical load margins are calculated based on the results and the weight of all the samples; finally the Cornish-Fisher series are introduced to estimate the probability distribution of the corresponding static voltage stability margins. The two-point estimating method is adopted to select sample points for deterministic calculational analysis, so that an un-deterministic problem is converted into a deterministic calculation; the voltage stability thresholds of all the sample points are found by utilizing the continuation power flow method, in this way, the voltage stability condition of a distribution network of a distributed power source including random output is estimated, and estimation accuracy is high.

Description

technical field [0001] The invention relates to a distribution network operation control technology and an analysis method for distributed power sources to be connected to the distribution network, in particular to a distribution network static voltage stability probability evaluation method based on a two-point estimation method. Background technique [0002] Voltage stability is the ability of a power system to continuously maintain acceptable voltages for all buses in the system under rated operating conditions and after disturbances. Static voltage stability refers to the ability of the system voltage to maintain or return to the allowable range without voltage collapse after the system is subjected to a small disturbance. Common load margins are used to evaluate. The so-called load margin refers to the total amount of load required to increase the load in a given direction until the voltage collapse point. [0003] The static voltage stability analysis method is based...

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Problems solved by technology

Among these three methods, the Monte Carlo method can directly simulate the probability distribution of the random variable to be obtained, while the analytical method and the approximate method need to calculate the moment or semi-invariant, and obtain the probability distribution through series expansion, which is widely used. is the Gram-Charlier series, but it has certain errors when it approximates the non-normal probability distribution

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