The Research And Application Of Flexible HVDC Technology In Wind Power Grid Integration

As a very promising renewable energy, the large-scale application of wind power isrestricted by the grid connection technology. The emergence of Flexible HVDCtechnology (VSC—HVDC) has provided a new way for the grid interconnection ofwind farms. As we can see in several international specific engineering, Flexible HVDCtechnology has a good application in the grid interconnection of wind farms.Considering the complexity of wind power grid system, due to the limited time andenergy, the paper will discuss the following three control targets, including the mostpower point tracking in motor side, the power factor and DC voltage stability in gridside. Research the application of VSC in the above aspect, design the control systemaccording the control targets. At last, the paper proves the validity of the control systemby simulation result.The paper establishes the VSC mathematical model in abc and dq coordinate system,having a study on VSC’s work mechanisms and control strategy. Based on the grid sidevoltage vector-oriented control strategy, the paper design the VSC double closed loopcontroller, which outer loop is power, DC voltage controller, and inner loop for currentcontroller. The paper simulates two AC system, which is connected by VSC—HVDC.and the simulation results shows that VSC can have a flexibility controlling on the acti-ve power, reactive power and other variables. At the same time, the simulation resultsindicate that space vector pulse width modulation has a high DC voltage utilization andlow harmonic rate.The paper compares several topological structure of permanent magnet directdriving system; the comparison shows the VSC topology can achieve a good controleffect. The paper discusses the control strategy of permanent magnet direct drivingsystem, which is combined by the VSC topology. In the motor side, the paper adopt therotor field vector-oriented control mode, in the grid side, the paper adopts the gridvoltage vector-oriented control mode, and completing the design of the control systemof both side.The paper completes all the construction of the simulation model in MATLAB/SIMULATION environment, and the simulation result shows the goodperformance of the control strategy, the goals of the system are achieved completely,which shows the effectiveness of the controller, at the same time, the result shows thatVSC—HVDC can be well applied in the interconnection of power wind.