Research On The Mechanism Of The Subsynchronous Oscillation Of The Wind Turbine Based On The Impedance Characteristics

Energy crisis and environmental pollution are the most concern of human society in the new century,in order to deal with the two problems,many countries carried out extensive research and application of various kinds of new energy,wind energy is one of them.Wind power generation not only does not pollute the environment,but also conforms to the concept of sustainable development,has been widely used in countries.Large scale wind power grid connected devices and non-ideal network can be connected together,but it will lead to a series of problems,such as resonance,power grid instability,which leads to the reduction of power quality.In order to solve the problem of power network instability,people have developed an impedance stability analysis method,using this method can help people to find the root of the problem and the potential resonance frequency range.In this study,the research of permanent magnet wind generator and DFIG wind power generator system,the impedance of interconnected system is stable under the guidance of relevant theory,and the output impedance model of asynchronous motor is created,in order to improve the stability of grid system.1.The comprehensive application of scientific method and model,analyzes the stability of permanent magnet wind turbine inverter system,DFIG rotor side power system of a network vulnerability,to reveal when the grid impedance and contr ol parameters of the system changes,the integral stability of the system with how to change.2.In view of the positive conditions,through the harmonic linearization method,creating a permanent magnet wind turbine system grid side inverter output impedance analytical model.In this process,taking into account the circuit structure,the rated operating point,phase locked loop,the potential of the filter inductance and other effects,summed up the relationship between them and the output impedance characteristics.3.The impedance model of stator-side of DFIG is built,considering the motor structure,operating point,phase locked loop,and current regulator.The output impedance of the whole system is also deduced and verified.