AY 2020 21 Test 1 Numerical part with solutions

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ELECTRIC CONVERSION FROM GREEN SOURCES OF ENERGY Prof. Alberto Dolara 1 ©Prof. Alberto Dolara – All rights reserverd Numerical exercise 1 < 29 June 2021 > The numerical data of this problem depend on your ID number, as follows: Example: ID number = 10123456 → U = 1, V = 2; W = 3; X = 4; Y = 5; Z = 6. Numerical data that depend on your ID number are highlighted by the symbol “←” along the text. A power processor for standalone Photovoltaic (PV) g enerator with Battery Energy Storage System (BESS) is composed by a unidirectional DC/DC converter, a bidirectional DC/DC converter and a three -phase PWM sharing the same DC bus, as shown in the picture on the right. Ratings are reported in the follow: Unidirectional DC/DC converter ratings (PV): ► Rated power, PPV,n 50 kW ► Input voltage range, VPV,n from 400 V to 800 V Bidirectional DC/DC converter ratings (BESS): ► Rated power, PBESS,n 30 kW ► Battery voltage range, VBESS,n from 240 V to 360 V Inverter: ► Rated power, PAC,n 50 kW ► Rated power factor, cosϕn 0.8 ► Rated frequency, f 50 Hz ► Rated AC side voltage, VAC,n 400 V (RMS, line to line) Grid: ► Rated grid voltage, Vgrid,n 400 V (RMS, line to line) Preliminary Definitions and Calculations 1. Calculate the minimum DC bus voltage that allow the inverter to operate in the linear region up to a grid voltage that is 5% higher than its rated value . The maximum voltage drop (in amplitude) across the inverter low -pass output filter is (7 + X) % ← of the rated grid voltage. Assume ideal switches. 2. Choose the more suitable unidirectional DC/DC converter for interfacing the PV generator to the DC link and calculate the minimum and maximum value of the duty cycle. Consider the DC bus voltage previously calculated and assume ideal switches. 3. Choose the more suitable…