The Wind Power System Based On Flexible Hvdc Technology Research

At present most of wind farms running uses the following means. MW wind turbine produce690VAC, turn into690V50Hz alternating current through AC-DC-AC converter, then the voltage rose to lOkV or35kV by the step-up transformer and was sent to main substation through parallel connected to Power Grid.The converter is installed in the tower, each wind turbine unit with a box-type substation, step-up transformer, it contains high and low voltage electric cases, etc.In traditional grid-connected way, because the wind farm with the local power grid is tight connected, any part failure will quickly spread to the other. In severe cases can cause substantial voltage oscillation of the whole system, angle instability, and wind farm stall. In addition there are many inadequate, such as big losses, high cost, and large area.In order to overcome these shortcomings, based on the VSC-HVDC, propose a new wind power system with decentralized rectification, boost and centralized inverter grid. Each wind turbine by uncontrolled rectifier and boost, use VSC-HVDC achieves HVDC transmission. Concentrated remitted high-voltage DC bus, constitute a multi-terminal DC transmission network, and then by the public high-voltage inverter realize grid-connected.The system does not require step-up transformer and box-type substation, have the following characteristics, such as low cost, the system loss is small, operation is reliable, and can achieve the unit group control.Its successful implementation will further reduce the cost of wind power, the market prospect is broad.In this thesis, the system was studied by the following aspects:the project will develop a rectifier, the DC boost converter, the high-voltage grid-connected inverter and other key equipment.The first chapter explains the background and significance of this paper, summarizes the development status of the VSC-HVDC.Chapter two describe the wind power system, which is decentralized rectification step, centralized inverter grid, makes theoretical analysis and formula derivation for boost power factor correction (PFC) principles, the inverter principle.Chapter three, on the basis of theoretical studies, establishing a model and Matlab/Simulink is used to simulate the model. The simulation results verify the correctness of the program.Chapter four, adopt TI’s DSP28335as the main chip, the IGBT as the power switching device, Design and generate hardware circuit with rectifier,PFC function DC boost converterChapter five, study control strategies and algorithms of the system, the programming design of software. Elaborate on the PI controller, AD sampling program design, and so on. Priority analyses the key of the inverter control for dead-time settings. Chapter sixth is a prototype was manufactured; through a lot of experiments verify the correctness of the theory.