| Developing off-grid wind power generating system is necessary to solve our country's power supply problems in areas far from power grids. Induction generator has many advantageous features, such as simple structure, low cost, reliable operation and so on, which is easy to meet wind power system's performance requirements, for example, high reliability and free maintenance. In this paper, a series of studies on off-grid wind power generating system are launched.The development status and trends of the domestic and international wind power has been introduced, the meaning and characteristics of off-grid wind power with induction generators has been revealed; the basic principles of wind turbine have been analyzed, a dynamic mathematical modeling of off-grid wind power system with induction generators has been conducted, the climbing method, based on the operating characteristics of wind turbine, has been used to maximize wind energy tracking, the coordinate transformation of the induction generator has been investigated, and magnetic saturation effects have been treated; effects of randomness of wind speed and volatility of loads on off-grid wind power system's frequency and voltage have been discussed, a strategy that uses a voltage source converter along-with battery energy storage system at its dc link, having the bi-direction flowing ability of energy, convenient to regulate active and reactive power for the stability control of system's voltage and frequency, has been proposed; the torque ripple of the generator caused by load imbalance has been greatly reduced by the application of negative sequence component compensation method.Finally, simulation model has been created by the simulation software MatLab/Simulink. The simulation results verify the correctness and feasibility of the control strategy. |
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