Evaluation Of Available Transfer Capability Considering Wind Power And Expected Loss Of Contingency

Available Transfer Capability(ATC),as an indicator to evaluate the security and reliability of power system,plays a vital role in the dispatching operation and planning and construction of power system.The development of regional interconnected power grid has brought a lot of uncertainty factors to the power system,which poses a great threat to the safe and stable operation of the power grid.How to deal with the uncertain factors reasonably and calculate the available transfer capability quickly and accurately is of great significance to the safety,reliability,economy and clean efficiency of power system.Therefore,this paper focuses on the calculation and evaluation of available transfer capability considering uncertainty factors from two aspects of wind power integration and electrical equipment failure.The main work is as follows:Firstly,a Latin hypercube-based wind power output prediction model is established.In view of the intermittent and random characteristics of wind speed,Weibull model and output model are used to predict wind speed and convert it into wind power output.The fluctuation of wind speed usually makes the output value fluctuate too much when it is brought into the system calculation.Latin hypercube sampling method is used to improve the coverage of random variable distribution space by sample value,and the correlation between variables is sorted by Cholesky decomposition,which improves the sampling efficiency and evaluation accuracy.Then,based on the Latin hypercube wind power output prediction model,the ATC calculation model of wind power grid-connected system based on optimal power flow is established.Aiming at the problem that the traditional algorithm has poor ability to jump out of local optimum and low effectiveness of calculation results,the cuckoo search algorithm is improved,and an Improved-Cuckoo-Search algorithm with chaotic initialization,mutation operator and dynamic discovery probability is constructed.Through the example analysis of IEEE-30 node and IEEE-118 node,the calculation of available transfer capability under wind power integration is evaluated,and the correctness and effectiveness of the improved algorithm are verified.Finally,in view of the limitations of conventional contingency screening and sorting in considering the probability of contingency occurrence and economic losses,this paper establishes an ATC bi-level optimization model considering the expected loss of contingency.The upper model defines the contingency state of the system,and the lower model uses the economic loss of ATC to optimize and correct the upper contingency.The Improved-Cuckoo-Search algorithm is used to solve the double-layer model by using its strong global optimization and fast convergence.The effectiveness of the model and algorithm is verified by IEEE-30 node simulation.