A METHOD AND DEVICE FOR IMPROVED UNDER-FREQUENCY LOAD SHEDDING IN ELECTRICAL POWER SYSTEMS

摘要

A method and device for load shedding in an electrical power system is proposed. The electrical power system includes a device that electrically couples one or more load feeder lines to the electrical power system, where each load feeder lines provides power to consumers. The method includes: monitoring the electrical frequency of the electrical power system and monitoring a frequency stability parameter, which is dependent on a rate of change of the electrical frequency. A control signal is generated to disconnect at least one load feeder line by the device when the monitored frequency is at or below at least a predetermined disconnection frequency threshold and the monitored frequency stability parameter is at or has passed at least one predetermined frequency stability parameter threshold. Using a frequency stability parameter that is dependent on the rate of change of frequency in addition to a fixed drop in frequency as a criterion when to shed load, permits the shedding of load to be postponed or even avoided altogether, and hence significantly decrease the risk of frequency overshoot that can lead to system instability and blackout. The method and device are particularly suited to electrical power systems with a high proportion of volatile, converter-based renewable generation sources.