Investigation Of The Electrically Excitied Synchronous Generator Wind Power Generation System Connected To Grid

In the big situation of the current globle’s depleting resources and deteriorating environment, development and utilization of renewable energy becomes an important part of sustainable development strategy. As a clean and extremely rich renewable energy, the research of wind energy aboat converting it into electrical power has became one of hot points both at home and abroad. Comparing to development and utilization technology of other renewable energys, wind energy technology has a significant progress and rapid development. But its main core technology is monopolized by other powerful wind energy foreign countries. The rearch of wind energy generation technology is very necessary.This paper first focuses on WEGS as a whole and elaborats the necessity of wind energy development and utilization% satatus and trends of wind energy generation both at home and abroad from the point of overview, then detailed summarys the categoris and disadvantages and advanteges of WEGS’s topology and system overall structure both current home and abroad、 detailed explained three control strategies commonly used in the WEGS.A wind turbine simulation system has been established. Wind turbine’s work principle is detailed analyzed. For its mathmatical model and power charateristic curve, in order to obtain the same power charateristic curve with wind turbine, based on the classical speed and current dual-loop control method adding the power outer loop to achieve the wind turbine simulation system. For the charateristic of VSCF WEGS, to improve wind energy capture rate, combining with the direct torque control(DTC) strategy, the optimal power/torque(OP/OT) control method is used to achieve maximum power tracking.The control strategies of generator side and grid side in WEGS has been researched. EESG DTC theory has been analyzed. It points out that in case of certain speed rapid controlling electromagnetic torque can quickly control the power output. In order to achieve grid-connected control, the grid side voltage oriented vector(OV) control strategy’s principle has been analyzed. It makes some simulations and experiments to the control strategies analyzed.For the advantage of power factor adiustable of EESG, in order to take full advantage of the converter capacity、cost savings and reduction of rotor winding loss, the DTC rotor excitation current control method has been analyzed to achieve the unity power factor control in the stator side. At the same time considering the changed motor parameters in the process of motor running, the integral compensation that stator flux vector and stator current vector is always perpendicular to achieve real unity power factor control.For direct drive EESG WEGS, the speed is very low and the voltage model stator flux observer is inaccurate. For achieving the full speed range DTC of wind energy generation, a rotor high-frequency current injection method has been proposed to observe the speed and rotor positon angle accuracy and using this rotor position angle in current model sator flux observation. This method can achieve sensorless wind energy generation. Simulations and experiments verify the sensorless grid-connected EESG WEGS proposed in this paper generation stable at zero and low speed.In order to verify the proposed control strategies, a digital hareware of grid-connected EESG WEGS is designed. This hareware usies TMS320F2812DSP as the control core and IGBT as the power switch. Experiment results show that the hareware works quickly and reliably.