Performance analysis of hybrid AC / DC microgrid under influence of battery energy storage location

Abstract

In microgrids, energy storage is generally located based on power management criteria and economic objectives that lean on the system's steady-state operation. However, the grid configuration, dynamics of primary energy sources, and storage type (AC or DC) impact its transient operation. This paper conducts a comparative study of the dynamic performance of Hybrid AC/DC Microgrids (HMGs) under the influence of Battery Energy Storage System (BESS) location, which has been neglected in the literature. The HMG performance is compared for one single BESS unit located either in AC or DC subgrid during various grid operational cases, considering interlinking converter (ILC) control topology that alters depending on the type of BESS. Two types of microgrid case studies with different structures have been considered, that is, a high inertia HMG and a converter-interfaced low inertia HMG. Simulation results reveal that the HMGs with both BESS locations perform robustly in handling grid disruptions. However, the BESS located in the DC sub-grid of a high inertia microgrid case presents an average of 40% higher quality of performance in key performance indicators compared to that of the AC sub-grid BESS. Conversely, the performance of the low inertia HMG with the BESS List of Symbols and Abbreviations: ω ref DG , ω Ã DG , reference and setpoint values of DG angular frequency; U ref DG ,U Ã DG , reference and setpoint values of DG voltage; U AC ,U DC , PCC voltage of ACg and DCg in the Case study I; U aci ,U dcj , bus voltages of ACg and DCg in the Case study II; ω,ω Ã ,U, U Ã , measured angular frequency and voltage (dq magnitude) of ACg and their setpoints; f AC , f ac , PCC and AC link frequency of ACg in the Case study I and II, respectively; U Ã dc , setpoint value of DCB terminal voltage; θ s , the phase angle of VSC output voltage; m DG ,n DG , active/reactive power droop coefficients of DG; m ACB ,n ACB , active/reactive power reverse droop coefficients of ACB in the Case study I; P DG , P ÃDG , active power of DG and its setpoint; Q DG ,Q Ã DG , reactive power of DG and its setpoint; P BESS , output power of battery energy storage system; P PV ,P WTG , P M , PV power, the active power of WTG, and mechanical power of induction motor in the Case study I; P L , P G , P loss , active power of AC Loads, DER generations, and line losses in the Case study I; P ACB ,P ref ACB ,P Ã ACB , output, reference, and setpoint active power of ACB in the Case study I; Q ACB ,Q ref ACB ,Q Ã ACB , output, reference, and setpoint reactive power of ACB in the Case study I; P ILC ,P Ã ILC , active power of ILC and its setpoint; Q ILC ,Q Ã ILC , reactive power of ILC and its setpoint; P ref , Q ref , active and reactive power reference of non-BESS DERs of ACg in the Case study II; I L ,I Lref , output current and its reference of non-BESS DERs of DCg in the Case study II; E 0 , R b ,Q, constant voltage, internal resistance, and charge capacity of the battery; K p , A,B, polarization constant and exponential zone voltages of the battery; U b ...