A Nonlinear, Bounded and Lipchitz Continuous Distributed Active Power Sharing Control Method for Islanded AC Microgrids

Abstract

In this paper, a nonlinear, bounded, distributed secondary control (DSC) method is proposed to coordinate all the distributed generators (DGs) in islanded AC microgrids (MGs). This proposed consensus-based DSC strategy can not only guarantee the restoration control of frequency and voltage but also realize an accurate active power sharing control. Through introducing a nonlinear dynamic from beta cumulative distribution function (CDF), the convergence speed of DSC is accelerated, the asymptotical convergence of DSC is ensured, and the transient overshoot of DSC is diminished compared with traditional DSC. Moreover, by ensuring the Lipchitz continuity characteristic of the control algorithm, the common chattering phenomenon in non-Lipchitz DSC scheme is eliminated. The stability and performance of the proposed DSC are also analyzed in this paper. An islanded AC microgrid test system with four inverter-based DGs is built in MATLAB/SIMULINK to further validate the effeteness of the proposed DSC strategy. INDEX TERMS Nonlinear distributed secondary control, islanded microgrid, multi-agent system, Lipchitz continuity, chattering phenomenon.

Robust Control Strategies for Microgrids: A Review

“…A nonlinear input-to-state stability (ISS) Lyapunov-based controller to stabilize the DC voltage of the DC microgrid and provide the frequency support to AC grids in grid-connected mode is proposed in [44]. In [45], a nonlinear and finite DSC method to coordinate all DGs in AC microgrids and control the AC voltage and frequency is proposed. A robust nonlinear decentralized control scheme for islanded DC microgrids to achieve the desired voltage at the DC bus, as well as maintain power balance, is developed in [46].…”

“…The improved performance of the proposed controller is shown and compared with the classic proportional-integral (PI) controller under CPLs. In [45], a consensus-based secondary control scheme is proposed for chattering-free power-sharing, as well as AC voltage/frequency restoration control, using Lipchitz-continuous secondary control scheme. Also, improvements are shown in terms of the transient overshoot and convergence speed through a cumulative distribution function.…”

Local adaptive pinning synchronisation for distributed secondary control of islanded microgrid

“…Distributed control strategies enable easier scalability, simpler communication network, and faster distributed data processing, which can facilitate highly efficient information sharing and decision making. Most of the secondary control-related works investigate the frequency regulation and active power sharing, and the trade-off between the voltage and reactive power sharing [10][11][12][13]. A distributed averaging proportional-integral (PI) controller in [11] is presented to provide a trade-off between the voltage regulation and reactive power sharing for secondary control.…”

Decentralize power sharing control strategy in islanded microgridsDecentralize power sharing control strategy in islanded microgrids

“…Because of the unavailability of the real time data variation in impedance, the DGs connect in the same network where accurate power sharing could not be guaranteed [20][21][22]. Q-V droop error has been investigated in [23] and authors proposed a novel technique that corrects the gain droop error according to the variation of the operating points of DG units.By computing all the disturbances of the real power where have been used in [24][25][26][27] to share an accurate power. Moreover, in this technique a low band communication has been used to initiate the signals from secondary controller by using the integral terms in order to manage the disturbances.…”

“…Reliability of the system is not guaranteed in this approach. Another serious problem of the technique is to maintain stability during load changes as stated in [27]. The output impedance mismatch among different DG units are significantly increased the errors in reactive power sharing precision as per the capacity of DGs connected in a network [28].…”