Three-phase Asynchronous Generator Load To Build Pressure And Switching The Load Analysis

The three-phase induction generator is paid attention by simple constructure, operating reliability, good dynamic performance, inexpensive cost, lack of DC field and brush, which represents the development tendency of the power generation block in isolated power systems. To understand the variables in different circumstances and provide the foundation for machine design, the development history, basis and importance are introduced firstly, and then there is a comparison between synchronous generators and induction generators anout advantages and disadvantages.The operating principle and no-load voltage buildup process of the induction generator are analyzed. The machine's parameters are obtained by tests. Based on the steady state equivalent circuit, the loop impedance equation is deduced. By setting the loop impedance to zero, the steady state voltage buildup condition is given. The variable-alternating method and golden cutting method are used to get the minimum self-excited capacitance and the minimum speed at no-load operating condition.The transient process of load connection/disconnection for the three-phase induction generator is studied. The transient mathematical model atαβ0 stationary reference frame is established and the state equations for resistive-inductive loads and for purely resistive loads are set up. The equations, which transform the stator currents and terminal voltages of the induction generator fromαβ0 stationary reference frame to original abc reference frame, are also given.The Runge-Kutta method, programmed by MATLAB language, is applied to solve for variable-coefficient differential equations with considering the effect of magnetizing current on the magnetizing inductance. The transient process of reststive-inductive load connection/disconnection for the three-phase induction generator is simulated, consequently, the stator currents, terminal voltages and magnetizing inductances are obtained. For separative resistive and inductive loads connection/disconnection, the simulation results and experimental results are compared, and the agreement between them shows that the presented analysis method is of validity and accuracy.