Research On Frequency Regulation Control Strategy Of High Wind Power Permeability System

The participation of large-scale wind power in power system frequency regulation can effectively reduce the burden of system frequency regulation and reduce system frequency fluctuations to ensure the stability of power system frequency.The current,most power systems operate in hierarchical partitions and multi-area interconnected operations state.Load Frequency Control plays a vital role in the safe operation of interconnected power systems.In an environment where the proportion of wind energy and other energy sources in the power system has risen sharply,the LFC problem of the interconnected power system is becoming more and more serious.On the one hand,traditional control methods such as PID cannot well track the changes in the actual nonlinear power system frequency,especially when the system exists in the time delay link,the frequency regulation effect is not satisfactory;on the other hand,variable-speed wind turbines are usually in the maximum power point tracking mode and cannot change the output in real time according to the system needs.Therefore,how to ensure the frequency stability of the power system after the wind power penetration rate is increased on the basis of the reserve power of the wind turbines participating in the system frequency regulation has gradually become an important direction of the power system load frequency control research.This paper considering the prospect of power system frequency regualation,the power control method of wind turbines is stduied.Under the premise of referring to the 5MW wind turbine model,study the reserve power control strategy of the wind turbine at different wind speeds,so that the wind turbine can achieve load reduction operation,and realize that the wind turbine can flexibly use the reserve power to respond to the system load and frequency regulation demand and study the impact of wind power on the system frequency after being connected to the grid.The interconnected system is modeled on the basis of analyzing the frequency control mode of the interconnected system and mastering the modeling principles of each part of the system.Based on the fact that the wind turbine has sufficient reserve power to track the frequency change of the system,in view of the limitation of conventional control when the power system includes a communication delay link,from the perspective of reducing the influence of communication delay on the frequency stability of wind power participating in frequency regulation,A control strategy based on the combination of forgetting factor recursive least squares(FFRLS)system identification method and improved generalized predictive control for wind turbines using standby power to participate in power system frequency regulation is proposed.First,the second frequency regulation model of single-area interconnected power system considering communication delay is established.Second,through the use of FFRLS algorithm for online identification,a controlled auto regressive moving average(CARMA)model of the difference equation of the controlled system with single input and single output is established.The system frequency deviation and wind farm power commands are used as output variables and control variables to design a generalized predictive controller.On the basis of constructing a predictive model considering the disturbance term,the optimal control rate of the system at the current moment is deduced,so as to realize the optimal control effect.Finally,the proposed control strategy is verified and compared with the optimal PID under different delay parameters and parameter perturbations.The results show that the proposed control strategy satisfies the stability of the system frequency.Compared with PID control,the system rise time is effectively shortened,and the overshoot is greatly reduced.