Study on the improvement of generators capabilyty in control of power system stability by ASPAC

本课题的目的是从磁通内部特性的观点分析电力系统中的负阻尼现象，提出一种新的磁通监测和控制的概念，并探讨工程实施中的一些实际问题。高响应AVR引起的负阻尼现象分析。明确了同步电机动态振荡时转矩、气隙磁链和转速之间相互作用的基本本质特征。这一结果构成了比以往任何时候都更精确地理解与动态稳定性相关的机器物理行为的基础。动态稳定性监测。直接从电机转矩、气隙磁链、转速等测量数据计算阻尼转矩系数和同步转矩系数的变化，可以成功地进行动态稳定性监测和负阻尼预测。动稳定控制方案。实验和仿真结果表明，所提出的控制方案在单机无穷大系统中有效地消除了AVR的无阻尼效应，扩大了系统的稳定极限。这些功能与先前开发的稳态稳定功能一起，将有助于增强ASPAC（自动稳定预测与控制）在提高电力系统稳定性方面的能力。但该方案在多机系统中的可行性尚需进一步研究，以最终应用于真实的电力系统中。

The object of this project is to analize the negative dampimng phenomena in the electric power system from the viewpoint of internal behavior of magnetic flux, to develop a new concept of its monitoring and control, and to scrutinize some of the practical problems associated with engineering implementation of this concept.Results in this study are summarized as follows:A. Analysis of negative damping phenomena caused by high-response AVR. The basic essential features of the interaction among electrical torque, air gap flux, and rotating speed in the synchronous machine during dynamic oscillationswere made clear. This result forms the basis for understanding the machine's physical behavior related to dynamic stability more precisely than ever.B. Monitoring of dynamic stability. Monitoring of dynamic stability and prediction of negative damping could be successfully made by calculating changes in both the damping torque coefficient and the synchronizing torque coefficient directly from measured data such as electrical torque, air gap flux, rotating speed and so on.C. Control scheme of dynamic stability. It was confirmed by both experiment and simulation that the proposed control scheme for canceling the undamping effect of AVR and extending the stability limit worked effectively in the one-machine connected to an infinite system. It was also made clear that these functions, accompanying by the previously developed one for steady-state stability, would contribute to add up the capability of ASPAC( Automatic Stability Prediction and Control) in enhancing the power system stability. But further research about the feasibility in the multi-machine system, which was beyond the scope of this project, will still be needed to apply this scheme eventually to the real electric power system.