Research On Evaluation Of Power Supply Capability Of Power System Considering The Randomness Of Distributed Power Supply

With the introduction of China's "Energy Development thirteenth Five Year Plan",more and more distributed power supply will be incorporated into the distribution network operation in the future,which improve the distribution network power supply capacity to a certain degree,but bring impact to operation and evaluation of the distribution network because of power output's randomness.At the same time,the rapid growth of the load in recent years puts forward higher requirements for the accurate assessment of the power supply capacity.While the traditional evaluation of power supply capacity does not take into account the influence of the randomness of distributed power supply,the evaluation result has great errors,which can not fully and truly reflect the actual operation of distribution network.In thesis,the concept of probability evaluation is introduced.Based on the traditional evaluation model,a power supply capacity evaluation system is proposed for the uncertainty of distribution network.Firstly,traditional evaluation methods are divided into radiation type and interconnected distribution network.The evaluation models and evaluation methods are studied respectively,which provide the basis for establishing new probability evaluation models.Secondly,the influence of distributed power access on power flow,voltage and load forecasting is studied.The load fluctuation parameter is determined by short-term forecasting and the load growth rate is determined by long-term forecast.The distributed power is optimized based on power circle configuration method,which selects a reasonable access plan according to the different access capacity.Thirdly,Considering the randomness of wind power and photovoltaic power generation,a stochastic model of the components and load is established,and the Cholesky decomposition math method is used to deal with the correlation of the distributed power supply.Probabilistic power plow algorithm is based on the semi-invariant method and Gram-Charlier Series.Finally,a probabilistic evaluation model of power supply capacity is established.The evaluation index system is put forward from the view of maximum power supply capacity and power supply capacity adaptability,and the probability evaluation process of power su pply capacity is determined based on probabilistic power flow algorithm.The analysis shows that the maximum power supply capacity with distributed power stochastic is no longer deterministic,but dynamic curve with probability distribution.The evaluation results are more accurate and reflect the actual operation of the distribution network.