AY 2021 22 Test 4 Numerical part with solutions

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ELECTRIC CONVERSION FROM GREEN SOURCES OF ENERGY Prof. Alberto Dolara 1 Numerical exercise 1 < 24 January 2023 > An hybrid power plant consists of: ► 1 PhotoVoltaic (PV) generator; ► 1 Wind turbine; ► 1 Battery Energy Storage System (BESS); ► connection to AC three-phase Medium Voltage (MV) grid by means of a transformer and AC/DC static converter; as sketched in the figure on the right. Generators and BESS are connected by means of a DC microgrid whose voltage is kept constant at the value of 600 V. Wind turbine is based on three-phase Permanent Magnet Synchronous Generator (PMSG) Ratings are reported in the follow: Generator and power converter ratings: ► PV Rated power, P PV 200 kW ► PV maximum power point voltage range, VMPP from 200 V to 850 V ► Wind turbine Maximum power, PW 100 kW ► Wind turbine output voltage range, VW from 450 V to 600 V (RMS, line-to-line) BESS converters and batteries: ► Rated power, PBESS 300 kW ► Battery side voltage range, VBESS from 360 V to 440 V ► Open circuit voltage, VOC (SOC) V OC (SOC) = 390 + SOC · 20 V (SOC = State Of Charge; 0 ≤ SOC ≤ 1) ► Equivalent internal resistance, Rbatt 50 mΩ Transformer nameplate: Rated frequency fn 50 Hz Vector group Dy11 Nominal apparent power SMVn 400 kVA Voltage ratings Nominal voltage MV (line-to-line) VMVn 15 kV Nominal voltage LV (line-to-line) VLVn 300 V Short circuit tests Short circuit voltage vcc 5,5 % Short circuit power factor cos(ϕcc ) 0.3 Open circuit test Open circuit active power P0 900 W Open circuit current I0 0.8 % (continued on next page) PV Generator Inverter MV Grid Trafo LV MV DC/DC B DC/DC A AC/DC BESS Wind generator G 3~ 2 Preliminary Definitions and Calculations 1. Choose the type of DC/DC converter suitable for interfacing the PV generator to the DC grid and calculate the…