跟踪COI思想应用于多机系统励磁控制

针对多机电力系统，提出了发电机功角和频率以动态跟踪系统惯量中心（COI）为目标的励磁控制思想。在该思想下，各发电机的功角按一定距离动态追踪系统COI功角的变化，而各发电机的频率则动态追踪系统COI频率的变化。相比于当前绝大多数以原运行点为发电机调节目标的控制思想而言，文中所提出的思想的主要特点在于它是利用系统的动态COI信号来将各发电机拉向同步，系统将根据实际情况稳定于某一可接受的频率，而不是局限于工频。在相同的发电机模型基础上，建立了2种不同思想下的控制系统模型，并给出了采用相同方法设计的鲁棒控制器。最后采用2区4机系统进行了动态仿真，以比较这2种鲁棒控制器以及自动电压调节器＋电力系统稳定器（AVR＋PSS）励磁系统在提高电力系统暂态稳定性方面的控制功效。

COI-tracking Concept for Excitation Control in Multi-machine Power Systems

Aiming at the excitation control in multi-machine power systems,the paper proposes the COI-traeking concept in which the angle of each generator tracks the angle COI of the system with a certain distance and the frequency of each generator tracks the frequency COI of the system.Compared to the currently used concept in which every generator is regulated towards the pre-fault operation point,the main characteristic of the COI-tracking concept is that it combines all generators together and makes them synchronous by the dynamic COI signals and the power system will settle in an acceptable frequency,which is not restricted to the power frequency.Based on the same model of the generator,two control system models are firstly established with the two control concepts respectively.Then,two robust controllers are designed using the same method.Finally,based on a 2-area 4-machine power system,dynamic simulations are carried out to make a comparison between the effects of AVR PSS excitation system and the two nonlinear robust controllers in improving transient stability of the system.