HIL based Coordinated Control of grid interfaced Distributed Generation assisted Battery Swapping Station Satabdy Jena Dept. of Electrical Engineering IIT Delhi Email:satabdy@gmail.com Gayadhar Panda Dept. of Electrical Engineering NIT Meghalaya Email:gayadharpanda@gmail.com Pierluigi Siano Dept. of Industrial Engineering University of Salerno, Italy Email:psiano@unisa.it Abstract—The large-scale world-wide adoption of Electric Vehicles as a mode of transportation is predicted to create stress on the already loaded power supply network. As such continued efforts in the area of distributed generation assisted charging stations are in full-swing. The paper investigates the outcomes of utilizing a PV assisted Battery Swapping Station to combat and alleviate simultaneously the issues of overburden and energy storage. A BSS can be tethered not only to provide battery swapping services to EVs but also provide for grid support, energy storage, ancillary services, etc. A grid interfaced PV assisted BSS system and its functioning in the smart grid environment has been proposed considering the system has a reliable and secure communication infrastructure. The multiple roles of the BSS and its coordinated functioning with the PV and the grid is examined under various test scenarios. The hardware prototyping of the control strategies for the inverter and the BSS is realized using Virtex-6 FPGA ML605 evaluation kit. The simulation and the hardware co-simulation results are presented to validate the efficacy of the proposed control scheme. Keywords—Battery swapping station (BSS) Hardware-in- loop (HIL) photovoltaic (PV)Field Programmable Gate Array (FPGA)State of Charge (SoC) I. I NTRODUCTION The potential of Grid connected Distributed Generation systems to supply for the large power deficits has made them inreasingly attractive but its intermittent nature restricts its ca- pability [1]. As such various energy storage systems (ESS) like fuel cell, flywheel, supercapacitors, etc. have been proposed in literature [2,3]. However, energy storage employing batteries is a most widely adopted technique because they are modular in nature, have silent operation and can be installed almost at any location [4]. Lead-acid batteries were generally used due to their cheap costs but research in the field of lithium- ion batteries has revolutionized the scenario [5,6]. Markets are now flooded with low-cost, high-lifetime Li ion batteries. The ability of battery swapping stations (BSS) for electric vehicles to emulate as an ESS has widened the scope of energy storage. The upperhand of BSS over charging stations for EVs is that it eliminates the need for vehicles to be parked for longer hours depending on the nature of the charger that may lead to overcrowding and stranding of vehicles at charging stations. Thus a BSS can be defined as a place at which a vehicle’s discharged battery or battery pack can be immediately swapped for a fully charged one, eliminating the delay involved in wait- ing for the vehicle’s battery to charge. The various interactions of the BSS are providing services to the EVs, collection of revenue from the customers, transactions with the electricity market to keep itself updated about the electricity tariff as discussed in [8,9]. Utilizing the storage capability of the BSS will enable it to perform arbitrage in the electricity market benefiting itself by higher profit margins. A grid connected energy storage system is discussed in [7] but its potential as a BSS for EVs is not discussed.As such a grid-connected mode of operation of a BSS is investigated in this paper. However co- ordination and exchange of information between the different DG units is a crucial criteria for the proper operation of the system and for providing ancillary services which can be achieved by having an effective and reliable infrastructure for communication which forms the basis of the future grid [10,11]. Advanced metering infrastructure (AMI) with a secure communication layer which is the core component of a Smart Grid infrastructure can form the backbone for implementation of ancillary services. The problems of the ever-increasing electricity demand, ageing power infrastructure, and degrading environmental impacts can be solved to an extent using the smart grid. The new vision of power management systems can be combined with two-way communication technology to create a truly intelligent system . The energy exchange thus has to be carried out by an ’Operator’ that continuously monitors and updates data. II. SYSTEM DESCRIPTION The structure of the proposed system consists of a dual- stage power conversion topology,a BSS, inverter-side filter and a step-down transformer to reduce the primary distribution voltage to a suitable level for interconnection with the network. The first stage is a DC/DC boost converter which also acts as a MPP Tracker and the second stage is a DC/AC inverter for exchange of power between the PV based BSS and the utility grid. Fig. 1 illustrates the block diagram of the proposed system. The InC algorithm has been used for MPPT due to its ease of implementation. It is based on the fact that the slope of the photovoltaic power-voltage (P pv - V pv ) characteristic curve is zero at MPP, positive on its left and negative on its right. The battery is modeled as a controlled voltage source model