Emergency load shedding to avoid risks of voltage instability using indicators

Abstract

This paper presents a new method to determine a viable load shedding scheme. This scheme presents to the system operator the location and amount of load to be shed to avoid a voltage collapse. In order to develop such a scheme in a timely fashion, indicators are developed to assess the risk of voltage collapse at a particular bus, and a sensitivity matrix coupling the amount of load to be shed and the indicator is computed. The method takes into account nonlinearities caused by generators reaching their limits of reactive power output. The advantages of the proposed method are viable network security, short computing times and low memory requirements due to the use of sparse vector techniques. The method developed has been tested with the 30 bus New-England test system and with a 206 bus 400 kV simplified French network with satisfactory results.