Operational Reliability Evaluation Of Power System Considering Primary Frequency Regulation Of Wind Power

Wind power generation has been recognized as an effective way to alleviate energy shortage,curb climate change and promote low carbon economic growth,as it has the advantages of clean,pollution-free and renewable.And it has been developing rapidly in recent years.However,due to the randomness,volatility and intermittency of wind energy,the power output of wind turbine(WT)have strong uncertainty.Large-scale wind power integration into power system will not only weaken the system frequency regulation capability,its uncertainty will also cause great frequency deviation,which exacerbates the risk of frequency limit violation.So it puts forward higher requirement on the operational reliability evaluation of wind integrated power system.With the increasing wind power penetration,WT participating in primary frequency regulation(PFR)of power system becomes the inevitable for the future power system.Therefore,it is necessary to carry out the research on operational reliability evaluation of power system considering PFR of wind power,so as to accurately quantify the frequency operational reliability level of wind integrated power system.Accordingly,the operational reliability evaluation of power system considering PFR of wind power is studied in this paper,focusing on the power flow model,the load shedding optimization model and the operational reliability evaluation method.The main research contents are as follows:(1)The current power flow models can not analyze the influence of WT participating in PFR on the power flow distribution as they do not consider the PFR ability of WT.To solve this problem,the power flow model incorporating PFR of WT is built.Firstly,based on the feature that the PFR capacity and active power-frequency characteristic coefficient of WT change with wind speed,the PFR equation of WT is given.Then,combining with the static regulation characteristic of the conventional generator and load,the power flow model considering PFR of WT is established and solved by Newton method.The simulation results of the modified IEEE 14-node system verify the correctness and effectiveness of the proposed power flow model.(2)The existing load shedding optimization models do not take into account the PFR ability of WT,and the frequency is at the lower limit value after load shedding.To get over this problem,the load shedding optimization model that takes into account of frequency regulation characteristic and minimum frequency deviation is constructed with the purpose of reconciling the load shedding amount and system frequency,by considering PFR of WT and non automatic generation control(AGC)unit,the PFR and secondary frequency regulation(SFR)of AGC unit,and by taking the weighted sum of load active power shedding amount and the square of frequency deviation as the optimization goal.And the predictor-corrector primal dual interior point method is taken to solve the proposed load shedding optimization model.The modified IEEE 14-node system is taken as simulation example to testify the correctness and effectiveness of the proposed load shedding optimization model.(3)To address the problem that the current operational reliability evaluation cannot quantify the frequency operational reliability level of power system,the operational reliability evaluation method of power system considering PFR of wind power is proposed,by considering the uncertainties including wind speed,the PFR capacity and active power-frequency characteristic coefficient of WT,and by combining with non-sequential Monte Carlo simulation method,the as-proposed power flow model and the as-proposed load shedding optimization model.And the evaluation indices reflecting the possibility and severity of upper/lower frequency limit violation are established to quantify the frequency operational reliability level.The correctness and effectiveness of the proposed evaluation method and evaluation indices is demonstrated on the modified IEEE-RTS 79 test system.