Research On Available Transfer Capability Of Power System With Wind Power

Available transfer capability (ATC) between areas in power system can directlyaffects the power generation and electricity consumption level, is always animportant indicator to be concerned in running and planning of power system. ATChas an important significance in maintaining system security, avoiding thetransmission congestion and effective guiding the transaction decision-making forpower market. To take full advantage of the resources of power transmission grid,improve system security and reliability, we must realize randomness and uncertaintyof wind power generation and further analyse its influence on transfer capability,study calculation and evaluation methods of ATC under different grid-connectedpattern of wind power generation.There was a certain degree of correlation between wind speeds which werelocated at wind farms or wind turbines. Existing wind speeds simulation methodswere inaccurate and low efficient, poor stability in the aspect of correlation degreedescription. In view of this, it was proposed that a combination approach of rankcorrelation coefficient in nonparametric statistics, Copula theory and traditionalMonte Carlo simulation to deal with correlation of wind speeds between differentlocations, at the same time Latin Hypercube skills based on stratified sampling wereadded into the sampling process, then a good stability, high efficiency wind speedssimulation method was put forward which can consider the wind speeds correlation,above conclusions laid a research basis for the follow-up contents of this paper.Because grid-connected wind power generation increased the uncertainty ofpower system, meanwhile brought stability problems, we must syntheticallyconsider the uncertainty and stability of the system in order to enhance thecredibility of ATC evaluation results. In view of this, based on proposed windspeeds simulation method, this paper brought fast voltage stability indices intocomputation model of ATC, and proposed ATC probability evaluation method withconstraints of voltage stability considering wind speeds correlation between windfarms. In the example analysis, this paper calculated minimum module eigenvaluefor power flow Jacobian matrix to test whether the system was able to keep voltagestability and studied the influence of wind speeds correlation on ATC, which revealsrelationship between different correlation coefficient of wind speeds and ATCsample values, mean, variance, respectively. The research results can providetheoretical support for the system operator to make the power transfer plan.This paper took considering capacity of conventional power generator sets in power source area whether was adequate as research basic point, from perspective ofwind power which might cause line blocking and thus limit the transfer capability,and made use of proposed wind speeds simulation method and ATC probabilityevaluation method to study the effect of the output power from wind farms in thedifferent areas or nodes on transfer capability. From the perspective of intermittentand randomness characteristic of wind power, the paper researched relationshipbetween uncertainty of wind power, penetration level and transfer capabilitybetween areas by introducing concept of risk degree. On this basis, in order tomaximize the benefit of the power enterprise, the optimal evaluation methods oftransfer capability consider centralized grid-connected wind generation was given.The distribution power grid with wind power generation may have a largenumbers of wind turbines, affected by the shortage of data and computationalcomplexity, we would not be able to get correlation coefficient matrix between windspeeds for location of the wind turbines. Aimed to above problem, this paper builtlimit related structures method and correlation variables sets method to deal with theproblem of the interdependent relationship between the input random variables inthe ATC evaluation. In ATC evaluation with large amounts of distributed windpower generation between areas of power system, the method could give ATCprobability information under all dependent structures of the input variables,reduced the uncertainty of wind power generation impact on the credibility ofevaluation results and it has important guiding significance to electric power trading,system operation and dispatching under uncertainty condition of dependentrelationship between the random variables.