Research On Operational Reliability Of Wind Integrated Power Systems Considering Uncertainty Factors Of Source-Grid-Load

In recent years,energy crisis and environmental problems have become increasingly prominent,it is imminent to vigorously develop and utilize clean energy such as wind power.However,due to the random fluctuation of wind turbine output,the operational status of power grid components is difficult to predict and control,and the level of load consumption is uncertain coupled with the reform of the demand side of the power market.More and more uncertainties exist in the operation of power system,and bring great impact to the system reliability level.Therefore,from the perspective of system operation,it is of great significance to accurately evaluate the reliability of wind integrated power system,predict the probability of system operational state in the future,and increase the capacity of wind power consumption taking into account the source-grid-load uncertainty factors.This paper mainly studies the operational reliability assessment of wind integrated power systems based on Markov chain considering uncertainty factors of source-grid-load,and research on nodal reliability and prioritization of demand response programs in wind intrgrated power system considering demand response.Firstly,the theory of operational reliability assessment of power systems is expounded.The commonly used index systems for operational reliability are introduced from three aspects of the representation of load loss,system operation state and degree categories.The basic principles and calculation process of the non-sequential and sequential Monte Carlo simulation evaluation methods are introduced.On the basis,the sequential Monte Carlo algorithm program is written in matlabR2014 a and the correctness and validity of this method are verified in the IEEE-RTS 79 test system.The simulation results shows that the sequential Monte Carlo simulation method not only can simutate components operational state and the duration of the transfer process,but also select system operation state,as well as provide reliability evaluation of the sample data.Besides,the problem of obtaining actual data of power system operation state is solved.Secondly,considering the impact of wind power output,component failure and load fluctuation on the reliability evaluation of the system,the source-grid-load uncertainty model is established.Econometrics software EViews6.0 is introduced to predict the wind speed sequence in a certain place,and the operational reliability model of wind farm is constructed.Based on the failure mechanism of conventional generator,the influence of aging failure and accidental failure on the conventional generator is taken into account,and the integrated time-varying operation model of conventional generator is proposed.Considering the weather condition and aging failure,the comprehensive time-varying operation model of transmission line is established as well.Based on the time-varying load model,the improved time-interval fuzzy clustering method is used to cluster the time with similar fluctuation of load curve.At the same time,a new clustering validity evaluation index is introduced to obtain the optimal clustering results,and a load comprehensive uncertainty model considering load volatility,diversity,correlation and directivity is established.The results show that the proposed models are more accurate and more suitable for operational reliability assessment.Thirdly,an operational reliability evaluation approach of wind integrated power system based on Markov chain considering uncertainty factors of source-grid-load is presented.First of all,Markov chain is introduced to divide system operational states into three categories: healthy,marginal and risky,and Markov chain model of wind integrated power system is constructed.Furthermore,a Markov system operational state transition matrix is obtained based on simulation data of the power system.According to the state transition matrix and current operational state,current reliability level can be evaluated accurately,and probability of the system state in the future can be predicted rapidly.Influence of the uncertainty factors on operational reliability is analyzed.Finally,effectiveness and rationality of the models and method were proved in modified IEEE-RTS79 test system.At length,in order to enhance the reliability and economy of wind integrated power system from the nodal viewpoint,a nodal reliability evaluation and prioritization of demand response(DR)program portfolios in wind integrated power system considering demand response was presented.Firstly,the user demand response load model was established.Secondly,analytic hierarchy process was employed to construct the hierarchical structure model of demand response portfolios.Moreover,based on the sequential Monte Carlo simulation method,a multi-segment optimal power flow approach was developed to evaluate the effect of DR program portfolios on short-term reliability of wind integrated power system from the perspective of the global and nodal.Finally,the effectiveness and rationality of the models and method were proved in the modified IEEE-RTS79 test system.The results show that the DR programs can effectively improve the system reliability and reduce the cost.According to the prioritization results of the demand response program portfolios,the evaluation result of the node reliability evaluation method was more accurate than the global method.At the same time,it further indicated the superiority of nodal evaluation and prioritization of DR programs to improve reliability and economy over the global method.