Automatic tuning of frequency and interchange power controllers in low-power energy systems

The present work discusses the development of algorithms for power controller autotuning under normal operation in power units of local energy systems having low synchronous generation, which can operate in stand-alone and parallel mode with the external power grid. The power controller of a power unit is tuned in the course of routine operation following the quality indicators of recorded transients under several load commutations upon a varying amplification factor. The amplification factor for each control channel is optimised by a function that approximates the dependence of the transient characteristics on the value of this factor, including the diversity of processes and mode disturbances during power surge/shedding. The sum of weighted overshoot and process duration values is used as a process quality indicator. Owing to adaptation, the controller automatically tunes itself over time, and the control quality improves. This article presents algorithms for autotuning the power controller when regulating frequency and interchange overcurrent under isolated and parallel operation mode of the MiniGrid, respectively. Unlike frequency controller, when the interchange overcurrent controller is autotuned by transient functions associated with load commutations, the algorithm filters out high-frequency power variations resulting from electromechanical oscillations. The simulation results of autotuning the power controller for an elementary scheme, having one generator, confirm the efficiency of the presented method and algorithms. The proposed method of autotuning frequency and interchange overcurrent controllers appears promising for technological enhancement and use in MiniGrid power control systems.

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