This paper addresses the necessity of monitoring systems for the surveillance of dynamic conditions and emergency control actions, operating on the short-term time frame, which can be armed as soon as potentially dangerous conditions are detected. In the paper, it is proposed the use of monitoring techniques which processes real time data coming from WAMS with an approach based on the wavelet spectral analysis. The key concept is monitoring the time-frequency evolution of the oscillation modes for detecting events occurring in the controlled area or in external systems. The approach has been tested on a simulation of the events of the 2003 Italian blackout. Furthermore, in this work, an approach based on dynamic optimization for assessing control actions aimed to mitigate the effect of cascading events is proposed. Control actions such as load/generation shedding and reactive power fast rescheduling have been considered. The procedure takes into account a detailed representation of the protection system with a particular attention to distance protections. In emergency condition, the assessment of control actions together with a detailed representation of the protection system is unavoidable since otherwise "remedy can do more harm than good". The proposed approach based on nonlinear programming techniques evaluates control actions aimed at ensuring transient stability and keeping system trajectories off the tripping zones of distance relays. The aim of the paper is to demonstrate the necessity of methodologies which can co-ordinate the contemporaneous use of all available resources (active and reactive) in order to control severe conditions and reduce, as much as possible, the impact of other more expensive control actions such as load/generation shedding. The proposed approach has been tested on a real-sized model of the Italian power system reproducing operating condition around 3:25 a.m., September 28th 2003 just before the point of no return of the major Italian cascading outage.
|Titolo:||Emergency control assessment for mitigating the effects of cascading outages|
|Data di pubblicazione:||2006|
|Nome del convegno:||41st International Conference on Large High Voltage Electric Systems 2006, CIGRE 2006|
|Appare nelle tipologie:||4.1 Contributo in Atti di convegno|