Research On Maximum Wind Energy Tracking Control System Of Brushless Double-Fed Wind Generator

With the scarcity of traditional fossil fuels and the growing problem of environmental pollution,it has aroused the attention of all countries in the world to the development and utilization of new energy,and has also promoted the rapid development of new energy technologies.As one of the important clean alternative energy sources in the future,wind energy has broad market prospects.As a new type of AC motor,the brushless double-fed generation eliminates the brush collecting ring in the traditional doubly-fed generation,and has the advantages of high reliability,small required frequency conversion capacity,flexible operation mode,and wind power generation and frequency conversion.Speed fields have good application prospects.The main research work of this paper on brushless doubly-fed wind generators is as follows:(1)Summarize the development trend of wind power generation system,and explain several common VSCF wind power generation systems,which highlights the potential advantages of brushless doubly-fed wind power generation systems.The research status and main control methods of brushless double-fed motors are analyzed.(2)The basic structure and operating principle of the BDFG special double stator winding are introduced.The energy conversion relationship and power flow direction of the brushless double-fed machine under subsynchronous,synchronous and super-synchronous operating conditions are analyzed in detail.At the same time,the BDFG is established.Mathematical Dynamic Models in Rotor Speed Coordinate System and Double Synchronization Speed Coordinate System.(3)By analyzing the operating characteristics of the wind turbine and the maximum wind energy capture mechanism,a wind turbine model was established to obtain the best power curve of the wind turbine.For the bidirectional flow characteristics of BDFG energy,dual PWM converters are used for control.Taking the grid-side converter as the research object,the vector-side decoupling control can make the grid-side converter work in the rectification and inverter state respectively,and realize the bidirectional flow of energy between the motor and the grid.To solve the problem of less research on the BDFG no-load grid-connected strategy,this paper deduces the BDFG no-load grid-connected simulation model by referring to the no-load feeder no-load networking strategy.At the same time,the power grid-connected control strategy was studied to complete the power decoupling and maximum wind energy tracking control.Finally,a flexible grid-connected and decoupled control scheme based on brushless doubly-fed generator is proposed.The feasibility of the scheme is analyzed through simulation.(4)For the brushless doubly-fed wind power generation system,first consider the constraints on the reactive power of the BDFG power winding by the rotor coupling current and the control winding current.After analyzing the steady-state equivalent circuit of the brushless double-fed motor under the generator convention,the reference active and reactive power of the motor is accurately calculated,and the function relationship between the copper consumption and the reactive power of the motor is found,and the lowest loss is proposed.Under the control method of maximum wind energy tracking of the brushless double-fed motor,the lowest copper consumption corresponding to the optimal reactive power is sought to ensure that the BDFG achieves the lowest copper consumption while tracking the maximum wind power.The control system simulation model was built in Simulink environment to verify the effectiveness and feasibility of the proposed method.