Multi-Objective Coordinated Optimization Control Over Wind Power Generation System

The development of clean energy and renewable energy is an inevitable move to solve the problems of energy security and ecological environment.Due to the relative maturity of technology and the comparative advantage of cost,wind power has been vigorously developed in China and around the world.With the increase of wind power penetration and the unit capacity of wind turbine,the structure of wind power generation system is becoming more and more complex,and various stakeholders in wind power have put forward higher requirements for wind power technology.It is of great significance to develop key technologies to improve the performance of wind turbines.Wind power is doomed to reach grid parity,which puts forward higher requirements for the cost of electricity generated by wind turbines.Increasing the power output of units that have been put into operation is an important means to reduce the cost of electricity.Natural wind is the only energy input to the unit.Its random fluctuations will directly lead to power fluctuations.Excessive power fluctuations will adversely affect the frequency control of the power grid.The large-scale tendency of wind turbines has brought about the increase in the weight and flexibility of the components of the unit,which has made the load on the unit more complicated.Optimizing load control of the unit is conducive to ensuring the unit’s safe operation.This paper focuses on three unit control goals of power generation optimization,limiting power fluctuations,and load optimization.This paper proposes multi-objective coordinated optimization control strategies for the unit and uses the joint real-time simulation platform based on Bladed and RTDS for verification.The key contents and main work of this paper include:(1)An improved power generation control strategy based on frequency division of wind speed is proposed to solve the contradiction between the goals of increasing power generation and limiting power fluctuations in the variable speed section,which takes into account the characteristics of the natural wind energy spectrum and the sensitive frequency band of the power grid.Through the frequency division control,the coordination and optimization of the goals of increasing power generation and limiting power fluctuation is achieved,and it is compared with other improved torque controls for analysis.(2)A pitch control strategy that separates the speed reference value and introduces integration acceleration,is proposed to solve the problem that torque control and pitch control can work wrongly near the rated wind speed,and to optimize the control switching process.(3)The change law of the pitch controller parameters above the rated wind speed may cause the unit to overspeed under gusts.Therefore,a fuzzy PI switching pitch control for gusts is proposed to achieve fast pitching in gusts without affecting pitch control performance when facing normal turbulent wind.(4)The Blade + RTDS hardware-in-the-loop real-time simulation platform for wind power generation system is established.The overall structure of the platform,hardware connection and data communication between modules are introduced in detail.The comparison and verification of multiple sets of control strategies are implemented on the platform,which proves the effectiveness of the proposed control strategies.