采用STATCOM与SEDC的多机系统次同步谐振抑制措施

Study on Damping Scheme of Subsynchronous Resonance in a Multi-Machine System by Combination of SEDC With STATCOM

并列同型的多台汽轮机组通过带串补线路送出时可能发生次同步谐振(subsynchronous resonance,SSR)。出力不均衡时,各机组轴系扭振行为不一致,在幅值和相位上均有差别。以双机系统为例,对并列多机系统发生SSR时各机组轴系扭振行为的差异进行了研究。时域仿真结果表明,将各机组发电机转速均取作输入信号时,仅采用静止同步补偿器(static var compensator,STATCOM)便可抑制所有机组的轴系扭振,但是抑制速度缓慢;以网侧STATCOM为主、机侧附加励磁阻尼控制(supplementary excitation damping,SEDC)为辅的联合SSR抑制措施可以结合SEDC和STATCOM各自作为SSR抑制措施的优点,快速有效地抑制多机系统SSR。

When the outputs of parallel-operated multi steam turbine generator units in the same type are sent out via a transmission line with serial compensation, the subsynchronous resonance （SSR） may occur. When unequally loaded, the .shafting torsional vibrations are different one another in amplitudes and phases. Taking a parallel-operated two-machine system composed of generators in the same type for example, the differences between torsional vibrations of the two shaftings under SSR are researched. Time-domain simulation results show that when rotating speed deviations of respective generators are taken as input signals, the torsional vibrations of all shaitings can be damped by using static var compensator （STATCOM） only, however the damping speed is slow; the combined damping measure composed of the STATCOM at grid side as the main means and the supplementary excitation damping control （SEDC） at generator side as the auxiliary means can damp SSR in multi generation unit system rapidly and effectively, meanwhile respective advantages of the two means in damping SSR can be brought into play.