Star Connected Three-phase Asynchronous Generator With A Single-phase Resistive Load Steady-state Operation

The steady-state performance of a Y-connected three-phase induction generator under single-phase operation with impedance load is analyzed, which focuses is on the effect of impedance load ,speed, combination between balance capacitances and excitation capacitances on the external characteristics. In the analysis process this paper expresses the relationship of positive sequence and negative sequence equivalent circuit variables based on the symmetrical component method, and deals with magnetizing reactance of the positive sequence and negative sequence according to the different equivalent circuits . Using the symmetrical component method,. the internal impedance of the self-excited three-phase induction generator under single-phase operation is derived. So the loop impedance is obtained. With both real and imaginary parts of the loop impedance equal to zero, the steady-state equations are established to predict the performance.Then the direct search method advocated by Hooke-Jeeves as a kind of optimization method is used to solve the equation and is analyzed, which is more stabilized and simpler. The loop impedance is derived using the symmetrical component method for single-phase steady-state operation. With both real and imaginary parts of the loop impedance equal to zero, the steady-state equations are established to predict the performance. The direct search method as a kind of optimization method is used to solve the equation for calculating external characteristics, which is simpler and more effective than Newton-Raphson method. The results show that the voltages of load are more sensitive to balance capacitances than to self-excited capacitances and the effect of load, speed, combination between balance capacitances and excitation capacitances on the external characteristics. The calculated values are in agreement with the experimental values, which verifies the accuracy of the presented method.Using symmetrical component method and the direct search method advocated by Hooke-Jeeves to solve and analyze external characteristics of self-excited three-phase induction generator under single-phase operation, is simple and possess general character. Under the values of given self-excited capacitors, rotor speed and load, external characteristics is obtained by calculating magnetizing reactance and frenquence.It is the fact that the voltage across the existing self-excited three-phase induction generator under single-phase operation is unstable, the ability applying to load is feeble, the paper analyzes the reason, the method of shunt-capacitor and series-capacitor balancing the unstable voltage is advocated..