Energy Evaluation And Dead Band Influence Mechanism Research Of Wind Power Participation In Frequency Regulation

With the increase of wind power penetration,the frequency regulation capability of power system decreases gradually.Various countries have made corresponding requirements for wind power grid connection,stipulating that wind power grid operation needs primary frequency regulation capability,and proposed a variety of frequency regulation control methods.However,frequency regulation capability of wind power is affected by many factors.On the one hand,the spatial distribution and stochastic volatility of wind speed make the energy of wind power frequency regulation uncertain,which leads to the inability of power grid to obtain accurate information of wind power frequency regulation capability,and the system frequency security is challenged.On the other hand,when wind power participates in power system primary frequency regulation,frequency regulation dead band is usually set.Unlike the fixed dead band determined by performance of traditional synchronous speed regulator equipment,frequency regulation dead band of wind power can be set flexibly in a large range and in a variety of setting methods.However,the mechanism of the nonlinear effect of frequency regulation dead band on wind power frequency regulation capability is not clear.In view of this,based on the perspective of wind power frequency regulation capability,this paper studies the method of wind power frequency regulation energy evaluation and the nonlinear influence mechanism of wind power frequency regulation dead band.Through evaluating wind power frequency regulation energy,the information of wind power frequency regulation capability can be visually displayed for the operation of power grid,and then provides reference for the tuning of wind power frequency regulation coefficient.By studying the mechanic influence of dead band on wind power frequency regulation capability and adjusting the frequency regulation coefficient,the adverse effect of dead band on wind power frequency regulation capability is reduced,and the expected frequency regulation capability of wind power is guaranteed,and the frequency safety of power grid is further improved.In the study of the influence of wind speed spatial characteristics and stochastic volatility on wind power frequency regulation capability,this paper analyzed the wind speed spatial distribution characteristics of wind farms on flat terrain,hilly terrain and offshore terrain respectively.On this basis,a mathematical model of wind speed distribution for each unit in the wind farm was constructed considering complex factors such as wake effect,terrain and so on.At the same time,considering the stochastic volatility of wind speed,the correlation among random wind speed,average wind speed and turbulence intensity is described by Copula function.Based on this,the probability density distribution function of random wind speed is obtained.Then,the available frequency regulation energy of wind turbines under different wind conditions is analyzed,and the energy loss caused by operating point offset is considered.Further,an evaluation method of the available frequency regulation energy of wind power is proposed,and the confidence interval of the available frequency regulation energy of wind power is obtained.The simulation results show that the proposed evaluation method can visually and clearly show the actual frequency regulation capability of wind power to the power grid,and provide a useful reference for the formulation of wind power frequency regulation strategy and the tuning of frequency regulation coefficient.In the study of mechanism research on the influence of dead band of wind power frequency regulation on frequency regulation capability,a system frequency response model considering the dead band of wind power primary frequency regulation is established.Based on this,the dynamic analysis expressions of frequency response of the system with ordinary and step frequency regulation dead band are solved.Furthermore,based on the frequency dynamic analysis solution considering the frequency dead band,two key frequency response indices of minimum frequency and steady frequency are solved.The influence of key parameters of wind power primary frequency regulation on important frequency indices of system is analyzed,and it is pointed out that the existence of common frequency dead band will weaken the primary frequency regulation capability of wind power.Then,in order to reduce the adverse effect of normal dead band on the wind power frequency regulation capability,a correction strategy of wind power primary frequency regulation factor is proposed to improve the system frequency regulation effect.The simulation results show that the dynamic resolution of frequency response considering the dead band of wind power frequency regulation has high accuracy,and the proposed correction coefficient strategy of primary frequency regulation can ensure the wind power frequency regulation capability,and reduce the system frequency deviation after disturbance,and improve the system frequency security.