Load frequency control of time-delayed power system based on event-triggered communication scheme

Abstract

In frequency regulation of power grids, conveying observations to controllers and obtaining control outputs depend greatly on communication and computation resources. Particularly for modern power system with an open communication network, the costs of communication and computation should not be ignored. This paper investigates an event-triggered based load frequency control for time-delayed power system with an open communication network. Based on the lifting technique in the sampled-data control theory, a new control scheme, using both a large sampling period and a maximized threshold parameter, is introduced to further lessen communication and computation costs while preserving a desired H∞ robust performance. The delay-dependent stability criterion of the proposed control scheme is less conservative, which takes fully the time delay, the sampling period, and the threshold parameter of event-triggered communication scheme into account. The proposed criterion is unified and can be transformed to the stability conditions of the existing research by setting different values of time delay, sampling and threshold parameter. Additionally, the usage of a large and aperiodic sampling period complies with the aperiodic updating characteristic of 2-4s in control signals in load frequency control scheme. Case studies based on a one-area power system, a two-area power system and an IEEE 39-bus benchmark test system are carried out. The simulation tests demonstrate that the proposed control scheme further reduces the communication and computation costs and ensures the load frequency control system stable operation with a preset H∞ robust performance.