Design and Stability of Load-Side Primary Frequency Control in Power Systems

• Published in: IEEE transactions on automatic control Vol. 59; no. 5; pp. 1177 - 1189
• Main Authors: Changhong Zhao, Topcu, Ufuk, Na Li, Low, Steven
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2014; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aggregates; Algorithms; Analytical models; Asymptotic properties; Buses (vehicles); Control systems; Decentralized control; Design engineering; Frequency control; Frequency measurement; Generators; Load; Load flow control; Load modeling; Networks; optimization; power system control; power system dynamics; Stress concentration
• ISSN: 0018-9286; 1558-2523
• DOI: 10.1109/TAC.2014.2298140

We present a systematic method to design ubiquitous continuous fast-acting distributed load control for primary frequency regulation in power networks, by formulating an optimal load control (OLC) problem where the objective is to minimize the aggregate cost of tracking an operating point subject to power balance over the network. We prove that the swing dynamics and the branch power flows, coupled with frequency-based load control, serve as a distributed primal-dual algorithm to solve OLC. We establish the global asymptotic stability of a multimachine network under such type of load-side primary frequency control. These results imply that the local frequency deviations on each bus convey exactly the right information about the global power imbalance for the loads to make individual decisions that turn out to be globally optimal. Simulations confirm that the proposed algorithm can rebalance power and resynchronize bus frequencies after a disturbance with significantly improved transient performance.