水电机组一次频率调节系统稳定性研究

Study on the stability of primary frequency regulating system of hydroelectric units

在"刚性联结"机组模型基础上,对水电机组并网一次频率调节系统稳定性进行分析。如果电网中存在多个小容量机组的调节系统稳定性较差,将会引起整个电网一次频率调节系统稳定性下降或不稳定情况发生。因此,必须重视小容量机组并入大电网运行时忽视系统稳定性的现象,足够的单机调节系统稳定性是多机调节系统稳定的保证。仿真研究表明:当各机组调节系统主导时间常数相同时,各执行机构动作趋于同步,电网频率调节系统才会获得良好的动态品质。由于"弹性联结"机组电磁同步力矩作用滞后,使调节系统整体稳定性较差;充分发挥励磁控制系统作用,有利于提高电网一次频率调节系统的稳定性。

If many small capacity units of poor-stability regulagting system are connected to the grid,then the stability of the primary frequency regulating（PFR） system of the entire grid would be lowered,or the grid becomes unsteady.Thus,a good stability of each isolated unit is a necessary condition to assure a stable multiunits sytem,and enough attention should be paid to the stability of small units on the grid.In this paper,the stability of hydroelectic units on the grid is analyzed by adopting a＂rigid coupling＂units model.Simulation results of this model show that a high dynamic performance of the PFR system can be achieved if the dominant time constants of regulating system of all units are the same and the movement of all the main servomotors are close to synchronization;while a lower PFR stability is often resulted from the lag electromechanical interaction of the synchronizing movement between＂elastic coupling＂units.Superior excitation control plays an important role in enhancing PFR stability of the grid.