汽轮机阀切换操作不当引发的电网低频振荡分析

Analysis of power grid low frequency oscillation caused by improper turbine valve switchover

通过数据图表对电网低频振荡过程中的主导模式进行分析。结果表明:随着电网单机容量的增大,机组的功率波动极易波及到电网。在大容量机组普遍采用快速励磁系统的情况下,虽然增加了电力系统静态稳定和暂态稳定,但也因系统阻尼减弱而产生动态不稳定。针对我国电网目前存在的机网协调不安全隐患,目前解决的主要办法是投入大机组的电力系统稳定器(PSS)并合理地整定其参数,同时合理设置数字式电液调节(DEH)和DCS一次调频的参数,使其既能满足电网频率快速响应的需求,又能满足机组安全稳定性的要求。而大容量区域电网间的直流稳控联网是最安全、经济的联网方式。

The dominant mode during power grid low-frequency oscillating process is analyzed based on reliable data and results show that： along with the capacity increase of individual generating unit, power grid is easily influenced by its power fluctuating. As the fast excitation system is widely adopted in large-capacity generating units, while the static stability and transient stability of power system are enhanced, the dynamic instability is also increased because of the decreased system damping. Aiming at the existing unsafe coordination of generator and grid in China,the main solution is to apply the power system stabilizer with rational parameter settings in large-capacity generating units and to properly set the parameters of primary frequency control for DEH control system and DCS in order to meet the requirements of the quick power grid frequency response and the safety and stability of power units. The adoption of DC stability-control networking system among large-capacity regional power grids is the most safe and economic networking mode.