基于闭环控制的独立电力系统低频减载策略

Close-loop Control Based Under-frequency Load Shedding Strategy Suitable for Isolated Power System

设计了一种基于比例-积分-微分(PID)控制思想的电力系统频率紧急控制策略。通过检测独立电力系统相关开关量的变化,识别发电机退出或出现与大电网解列等严重事故,根据所测量的退出电源容量迅速启动低频减载(UFLS)装置的紧急启动轮,以尽快抑制频率的急剧下降。在后续的调节过程中,引入PID闭环控制策略对频率进行跟踪控制,并引入粗调轮和细调轮的概念以应对频率的不同变化阶段。最后通过EMTDC仿真试验验证了所提出的方法有效性。

A power system frequency control strategy based on the proportional-integral-derivative （PID） control method is designed. By detecting the variation of the circuit breaker status in an isolated power system, serious faults such as a generator outage and disconnection from the main grid can be identified, then the emergency pick-up step of the under-frequency load shedding （UFLS） device can be immediately started according to the capacity of the removed power, so the abrupt drop of frequency will be restrained. In the subsequent regulating process, the concept of PID closed-loop control strategy is proposed to trace and control the frequency change. Furthermore, the concept of the rough and fine-adjusting step is proposed to cope with the different phases of the frequency variation. The effectiveness of the control strategy proposed has been verified by EMTDC simulations. In addition, the PID frequency control algorithm can be extended to UFLS device of conventional power systems.