Distributed Voltage Control for Microgrids Against Time-Varying Communication Delay Interference

Abstract

In islanded microgrids, the state-of-the-art distributed controller will suffer from control errors under the interference of time-varying communication delay. Towards this end, a distributed average consensus estimator is proposed to track the dynamic signal averages regardless of time-varying delay. On this basis, a distributed voltage controller resisting time-varying delay interference is proposed to precisely achieve average voltage recovery and the proportional reactive power sharing, and to constrain the voltage over-limit by introducing an additional signal, which is not possible with state-of-the-art distributed controllers. Also, the inaccurate estimation of the delay upper bound will lead to the improper parameter design, and then the controller is at risk of losing dynamic performance or instability. For this problem, the stochastic network calculus (SNC) is used to derive the tight upper bound of time-varying delay, and then the delayed discrete matrix is constructed to solve multi-delay transcendental equation, by which a parameter design algorithm is presented. Finally, the hardware-in-the-loop (HIL) experimental platform is built, and the performance of the proposed controller is tested jointly with OPNET. Compared to the state-of-the-art controller, the proposed controller has the advantages of high control accuracy, superior stability, fast convergence and no voltage crossing under the time-varying delay.