Analysis And Suppression Method Research Of Motor Terminal Over-Voltage In Doubly-Fed Wind Power Generation System

In recent years,with the global energy shortage and traditional energy such as fog and a series of environmental problems,it is imminent to solve these problems.Therefore,some new clean energy is studied,such as the use of wind energy has gone through a breakthrough development.Found in the doubly-fed wind power system operation,the rotor side PWM converter drives the doubly-fed motor through the long-term cable,The terminal voltage of motor will appear over-voltage and high-frequency damping oscillation,when it is in severe cases,it can lead to the rotor winding and subset ring premature damage,and greatly reduce the service life of the generator.When the PWM pulse drives,The main factors that causes the motor over-voltage are the effect of the pulse rise time,And the parameters(inductance,resistance,capacitance,length)of the long cable with the motor impedance cannot match.Firstly in this paper,the control strategy of the rotor side of PWM converter is analyzed to reduce the influence of the PWM drive system on the motor side over-voltage.Secondly,using the knowledge of transmission line theory,The mathematical model of the converter drive motor by long cable is established,and the mathematical description of the over-voltage is obtained.The relationship of over-voltage,cable length,capacitance,inductance and pulse rise time are established.And Related system model in the MATLAB simulation software is set up,The results that long-term distribution parameters of the cable itself lead to the motor terminalover-voltage and interpret is reached,and which was studied.Finally,two kinds of filters are proposed to suppress the over-voltage of the motor,and the suppression effect is tested through simulation.Because of these two kinds of suppression methods are mostly using the test method or experimental method,and which is used to determine the filter parameters,and it did not give a clear parameter settings.The transfer function analysis was introduced to improve the calculation method of the two filter parameters,and which is verified through simulation.And the effectiveness of the two methods of over-voltage suppression are verified in the doubly-fed power generation simulation system.