Distributed Load-Side Control: Coping with Variation of Renewable Generations
This paper addresses the distributed frequency control problem in a multi-area power system taking into account of unknown time-varying power imbalance. Particularly, fast controllable loads are utilized to restore system frequency under changing power imbalance in an optimal manner. The imbalanced power causing frequency deviation is decomposed into three parts: a known constant part, an unknown low-frequency variation and a high-frequency residual. The known steady part is usually the prediction of power imbalance. The variation may result from the fluctuation of renewable resources, electric vehicle charging, etc., which is usually unknown to operators. The high-frequency residual is also unknown and treated as an external disturbance. Correspondingly, in this paper, we resolve the following three problems in different timescales: (1) allocate the steady part of power imbalance economically; (2) mitigate the effect of unknown low-frequency power variation locally; (3) attenuate unknown high-frequency disturbances. To this end, a distributed controller combining consensus method with adaptive internal model control is proposed. We first prove that the closed-loop system is asymptotically stable and converges to the optimal solution of an optimization problem if the external disturbance is not included. We then prove that the power variation can be mitigated accurately. Furthermore, we show that the closed-loop system is robust against both parameter uncertainty and external disturbances. The New England system is used to verify the efficacy of our design.
© 2019 Elsevier Ltd. Received 23 March 2018, Revised 11 July 2019, Accepted 8 August 2019, Available online 30 August 2019. This work was supported by the National Natural Science Foundation of China (No. 51677100, U1766206, No. 51621065), the US National Science Foundation through grants CCF 1637598, ECCS 1619352, CPS 1739355, and ARPA-E, United States through grant DE-AR0000699. The material in this paper was not presented at any conference. This paper was recommended for publication in revised form by Associate Editor Antonella Ferrara under the direction of Editor Thomas Parisini.
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