Trends in WAMS-based under-frequency load shedding protection

In this paper some important issues are brought up with respect to the use of wide-area monitoring system for under-frequency load shedding protection. In order to understand them, some basic knowledge about the power-system frequency behavior is first given. The forecast of trends in future under-frequency protection development is provided from the authors' point of view, which appears be in the form of predictive concept as a sub-category of adaptive under-frequency load shedding schemes. Additionally, the idea of distributing the shedding-decision from centralized system is explored, which is currently under thorough investigation. This briefly presented local predictive under-frequency load shedding concept is in full conformity with the conservative philosophy that the wide-area approach to the power-system protection should be installed as a smart supplement to a local one in order to compensate the risk of a communication network failure, which is a core element of wide-area monitoring, protection and control system.