| In recent years,people’s demand for efficient and convenient power systems has continued to increase,which has promoted the development of microgrid technology.As an emerging technology,a microgrid can switch operations in two different modes,namely island mode,and grid-connected mode.It has a more flexible control method than a traditional power supply.Energy Storage Systems(ESS)are vital to improving the reliability of an islanded MG.In the islanded operation,the microgrid has to maintain voltage and frequency within acceptable range independently of the utility grid.In this research work,a distributed control strategy integrated with a multi-agentbased average consensus algorithm is presented for the Distributed Energy Storage Systems(DESS)in islanded AC micro-grid.A hierarchical control structure is implemented that consists of three control levels,i.e.: inner controls,primary controls,and secondary controls.The secondary control layer consists of estimators for injected power and system frequency.Power-sharing is achieved with adaptive droop control.The multi-agent-based average consensus algorithm is implemented to obtain an average estimate of frequency and active power.A voltage compensation method is given to ensure that the voltage of PCC is within the acceptable range.Reactive power sharing and voltage restoration algorithms adopt the integration of reactive power and active power respectively.The proposed method does not require an additional voltage restoration loop at a higher control level.It is designed for an Islanded MG operation where the DGUs in the MG network form the system voltage and frequency and share active and reactive power load demands for the local load.The resilience of the proposed control scheme towards load changes is also investigated.A six nodes test system with three energy storage systems is simulated to verify the proposed control strategy in terms of powersharing among DESS and restore voltage and frequency to a nominal accepted range. |
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