| With the continuous expansion of the scale of the interconnected power grid and the expansion of the installed capacity of wind turbines,the strong randomness and intermittent of wind power and the interaction of a large number of power electronic devices make the problem of low frequency oscillation of power system more complicated,so it is necessary to conduct in-depth research on this.In order to improve the acceptable level of wind power to the power grid,a large number of energy storage devices are connected to the power system.How to make full use of the energy storage device to stabilize the power system requires us to study the location and capacity of these energy storage devices.So,it is necessary to study the optimal configuration of energy storage systems for suppressing the low-frequency oscillation of the power system including wind farm.In this paper,by analyzing the application status of energy storage technology,the energy storage device suitable for suppressing low frequency oscillation of the system is selected,and the model of energy storage device is established.The two main shortcomings of the commonly used energy storage model control methods can be summarized as:independent adjustment of active and reactive power cannot be achieved and frequency information of the system cannot be used to adjust the output power.Based on the common energy storage control method,the feedforward decoupling control method and the feedforward decoupling double loop control method are studied.The effect is ideal,and the energy storage system model is established under PSASP software.In this paper,the large-scale power system with complex influences between various variables is divided into a network-side small-signal model and a component-side small-signal model.Based on the simplified model,a current-based small-signal model of synchronous generator and doubly-fed wind turbine are established.The feedforward decoupling double loop control method for energy storage has no transient model and small signal model.In this paper,the principle of phase lock loop is used to introduce the local frequency change information of the transient process into the energy storage control mode,and finally the transient model and small signal model for energy storage are established.The component side model accesses the network side model through the terminal voltage and the injected grid current,eventually a state-wide state matrix is formed.By analyzing the eigenvalues,it can be determined whether the system is unstable and the oscillation mode is determined.Then this paper studies the optimal configuration method of energy storage,and determines that the objective function is that the capacity of energy storage system is the smallest,and the constraint condition is that all the real part of the characteristic value of the power system state matrix are negative.Intelligent algorithms such as genetic algorithm can solve such optimization problems well.This paper designs a genetic algorithm for energy storage optimization configuration,which optimizes the location and capacity of energy storage devices.In the chapter of the case analysis,the designed energy storage system is first connected to the single-machine infinity system,and its ability to suppress the low-frequency oscillation of the power grid is verified.Then,the wind farm is connected to the IEEE-39 system,and the model analysis is realized by MATLAB programming.The inhibitory effect of energy storage on the low-frequency oscillation of the system is studied.The genetic algorithm is used to optimize the energy storage configuration,and the optimal scheme based on the ability to suppress low frequency oscillation of the system is determined.Finally,PSASP simulation method is adopted to verify the above results. |
PDF Full Text Request