Research On Active Power Dispatching And Frequency Optimization Control Of Wind Farm

With the increasing consumption of fossil energy and climate change,renewable energy represented by wind power has achieved tremendous technological progress in the past two decades and is widely used on a global scale.The use of clean energy has become an important means of solving the energy crisis and environmental problem.However,due to the characteristics of natural resources such as wind energy,renewable energy generally has more randomness and volatility than traditional energy sources.With the gradual increase of the penetration rate of wind power in the power system,the proportion of synchronous units in the system as the main force of peaking and frequency regulation is further reduced,which brings challenges to the safe and stable operation of the power system.Therefore,the power grid urgently needs the wind farm to have effective active power control capability,and participate in the auxiliary service of the system peaking and frequency regulation,thereby improving the grid friendliness of the wind power.This paper establishes a framework for active power control of large wind farms under the guidance of the power grid.The optimization algorithm and control strategy are proposed and validated from the aspects of active power optimal scheduling during daily limited power operation and frequency support in the event of failure.The main work has the following points:1.On the basis of the wind turbine mechanism model,the realization scheme of the wind turbine's limited power operation is discussed.At the same time,through the analysis of the fatigue structure in the wind turbine,the calculation method of the Damage Equivalent Load(DEL)of the unit is introduced.Combined with the variation characteristics of the rotor speed and the pitch angle in different power limiting strategies,the fatigue load of wind turbines under each limited power strategy is simulated and calculated,and the limited power strategy of wind turbines used in the wind farm dispatching strategy in the following chapters is determined.2.Under the premise of limited power operation of the wind turbine,the power optimization scheduling strategy of the wind farm is designed,and the optimization target is the fatigue load of the wind turbine in the wind farm.On the basis of the theoretical calculation method of the fatigue load of a single wind turbine,the corresponding relationship between the operating state of the wind turbine and the fatigue load is obtained by using the look-up table.In this paper,the wind speed data of each wind turbine is preprocessed by the empirical mode decomposition strategy,and then the accelerated particle swarm optimization algorithm is used to solve optimization problem with the wind turbines under different wind speeds.Compared with the traditional strategy,the strategy can realize the optimal dispatching of fatigue load while completing the active power target of the wind farm.3.Combined with the analysis of the fatigue load of a single wind turbine,this paper designs a dynamic grouping algorithm for wind farm to achieve the smoothing of scheduling instruction for each unit.Considering the intelligent development trend of equipment,this paper introduces a fully distributed active power dispatching strategy based on an unsupervised multi-agent system.In order to meet the needs of dynamic grouping,this paper improves the proposed multi-agent algorithm and proposes a piecewise consistency algorithm for parameter virtual update.The simulation results show that the proposed algorithm can complete the smoothing of the active power of the unit under the completely distributed power allocation framework.4.Through the analysis of the mechanism model of the wind turbine participating in the system frequency regulation in the Maximum power point tracking mode,the linearized expression of the wind turbine's frequency regulation model is realized based on the small signal analysis method.Further,the gap metric between the frequency models under different wind conditions is calculated,and the similar model is merged to establish an equivalent model of the wind farm participating in the frequency regulation.Compared with the high-order nonlinear model,the experimental results show that the proposed equivalent linear linear frequency regulation model has good validity and accuracy.5.Combine the wind farm equivalent linear frequency regulation model with the frequency regulation model of traditional synchronous unit to build a frequency control model of multi-region hybrid energy power system with wind power and thermal power.Based on the model predictive control strategy,an optimized frequency controller for multi-region hybrid energy is designed.The superiority of the optimized control algorithm proposed in this paper is proved by the comparison with the traditional droop control strategy.