水轮发电机组短路故障时机电耦联的扭振问题研究

首先采用一种统一的机电耦联的新方法，找到发电机组机电耦联系统的微分方程组，经变换得到方程组的解，进行数值计算，得到三相短路、两相线间短路及一相对中短路时各机、电变量的变化规律。得知短路时电磁力矩很大，其振荡频率为50Hz或100Hz，幅值可达到额定扭矩的数倍，甚至更高，故要引起很大的冲击扭振应力，当轴系扭振固有频率接近50Hz或100Hz时，会发生强烈的共振。并进行了实验研究，说明理论结果和实验结果相吻合。研究结果对水轮发电机组轴系的安全运行有重要的应用价值，对轴系的设计有指导价值。

STUDY ON COUPLED MECHANICAL AND ELECTRIC TORSIONAL VIBRATION PROBLEMS OF HYDROELECTRIC GENERATING SET WHEN SHORT-CIRCUITED SUDDENLY

A set of nonlinear differential equations for mechanical and electric system of generating set is derived by a new unified electromechanical coupling method. The solutions of equations are obtained by a series of transformation. Under the condition of three phases, two phases and one phase suddenly short circuit, the rule of the change for mechanical and electrical variables are obtained through numerical calculation. It is known that the frequency of electromagnetic torque is 50?Hz or 100?Hz, and the electromagnetic torque is very large, their amplitude are several times as many as nominal torque or more. When the natural frequency of torsional vibration is close to 50?Hz or 100?Hz, the resonance of shaft system will happen. The experimental research was then carried out. The theoretical results are shown to be in good agreement with the experimental results. The research results is of great application worth in the safety operation of shaft system of hydroelectric generating set, and more, these results is significant in design of shaft system of generating set.