Improving the Storage Capability of a Microgrid with a Vehicle-to-Grid Interface Vicente Leite, Ângela Ferreira and José Batista Polytechnic Institute of Bragança, Portugal Outline • Motivation • The IPB microgrid • Energy storage capability • IPB Eco Buggy • V2G and G2V interface • • • • Bidirectional power converter topology Control strategies Simulation results Experimental results • Conclusions Motivation • Energy storage systems enhance the exploitation of Renewable Energy Sources (RES) • Minimization of intermittency and variability effects of most RES • Balance in system cost • Contribution to frequency and voltage stability by providing ancillary services • Backup active power, acting as a manageable load and discharging energy back to the grid when necessary • Reactive power support • Peak-shaving • Under a microgrid concept, plug-in electric vehicles (PEV) have an important distributed energy storage capacity • Deployment of battery chargers to allow a bidirectional power flow • Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) concept IPB Microgrid Infrastructures PV glass facade of the library Photovoltaic systems SB 2100TL Wind turbine SB 3000 Pico hydro power plant WB 1700 WB 1200 SB 1200 Loads Microgrid 230V, 50Hz SB 5048 Bi-directional battery inverter for off-grid systems DC voltage LiFePO4 Battery Biodiesel production unit Generator ECO Buggy IPB Battery bank Microgrid set up in the laboratory Energy storage capability Semi-automatic production unit of biodiesel from used cooking oil and (bio)diesel GenSet (5 kW) Bank of batteries 8×6V, 200A Electric vehicle battery IPB Eco Buggy Motor Axial Flux PMSM High efficiency High torque density 13 kW; 64,87 V; 149,5 A; 6000 rpm; 20,7 Nm; 8 poles; 400 Hz Battery LiFePO4 Low cost of raw materials Long life cycle Safety characteristics 96 V; 70 Ah; 90 Kg V2G/ G2V interface Bidirectional power converter topology V2G/ G2V interface Control strategies V2G (discharge) and G2V (charge) control * P Vbat. ÷ * I b, V2G Current (A) * I b, G2V Voltage (V) Ib V2G/ G2V interface d vg = vgd = v q id Voltage Oriented Control of the VSI i iq i d* Vdc* ÷ Q* v i q* v d' v q' v*d vc* = vα* vgd v *q vgq = 0 vg = vgd = v Simulation results 500 Vdc sim Vdc ref 480 DC-Link Voltage (V) 460 440 420 400 380 360 340 320 300 0.5 1 1.5 2 Time(s) G2V P ≈1000 W 2.5 3 3.5 4 V2G P = 1000 W Q = 0 var P=0W Q= Q= - 400 var 400 var Battery voltage (V) Battery current (A) Simulation results 20 ib sim ib ref 10 0 -10 -20 0.5 1 1.5 2 Time(s) 2.5 3 3.5 4 0.5 1 1.5 2 Time(s) 2.5 3 3.5 4 99.8 99.7 99.6 99.5 99.4 G2V P ≈1000 W V2G P = 1000 W Q = 0 var P=0W Q= Q= - 400 var 400 var Simulation results 10 d current (A) 5 id ref id sim 0 -5 -10 0.5 1 1.5 2 Time(s) 2.5 3 3.5 4 1 1.5 2 Time(s) 2.5 3 3.5 4 q current (A) 4 2 iq sim iq ref 0 -2 -4 0.5 G2V P ≈1000 W V2G P = 1000 W Q = 0 var P=0W Q= Q= - 400 var 400 var Simulation results Vg/30 Ig Ig amp Grid Voltage (V) and Current (A) 15 10 5 0 -5 -10 1.4 1.45 G2V 1.5 1.55 1.6 Time(s) 1.65 V2G 1.7 1.75 Simulation results Vg/30 Ig Ig amp Grid Voltage (V) and Current (A) 15 10 5 0 -5 -10 2.3 2.35 2.4 P = 1000 W 2.45 2.5 Time(s) 2.55 2.6 P =0W 2.65 2.7 Simulation results Vg/30 Ig Ig amp Grid Voltage (V) and Current (A) 15 10 5 0 -5 -10 2.9 2.92 2.94 2.96 Q = 0 var 2.98 3 Time(s) 3.02 3.04 3.06 Q = - 400 var 3.08 3.1 Simulation results Vg/30 Ig Ig amp Grid Voltage (V) and Current (A) 15 10 5 0 -5 -10 3.4 3.42 3.44 3.46 3.48 Q = - 400 var 3.5 Time(s) 3.52 3.54 3.56 Q = 400 var 3.58 3.6 Experimental results 8 400 0 Vg -200 -400 id and iq (A) Vg, V pll (V) 200 0.04 0.05 0.06 0.07 Time(s) 0.08 id iq 4 2 Vpll 0.03 V g/30 (V ), ig and Ig (A ) 10 6 0 -2 0.09 0 0.05 Grid voltage and PLL output 0.1 Time(s) 0.15 5 0 -5 Vg/30 ig ig amp -10 -15 0.2 0.02 Grid current dq components 0.04 0.06 0.08 Time(s) 0.1 0.12 0.14 Step in the reactive power reference (-500 var) 1500 1000 1000 0 -5 Vg/30 ig ig amp -10 -15 0 0.05 0.1 Time(s) 0.15 Step in the active power reference (400 W) 0.2 V dc (V ), p (W ), q (V ar) 5 V dc (V), p (W ), q (V ar) Vg/30 (V ), ig and Ig (A ) 10 Vdc p-meas q-meas 500 0 0 0.05 0.1 Time(s) 0.15 Step in the active power reference (400 W) 0.2 800 600 400 200 Vdc p-meas q-meas 0 -200 0 0.05 0.1 Time(s) 0.15 Step in the reactive power reference (500 var) 0.2 Conclusions • The V2G/G2V interface project will provide an additional energy storage element • The vehicle’s battery improves the storage capability of the microgrid • It acts as a manageable load or generator, smoothing the load diagram • The adopted topology and control strategies are able to manage bidirectional active and reactive power flow • Allow reactive power support • Improve the reliability and quality criteria of the energy supply Muchas gracias Vicente Leite [email protected]
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