AY 2022 23 Test 1 Numerical part with solutions

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ELECTRIC CONVERSION FROM GREEN SOURCES OF ENERGY Prof. Alberto Dolara ©Prof. Alberto Dolara – All rights reserverd 1 Numerical exercise 1 < 27 June 2023 > A 500 V DC microgrid consists of: ► A PhotoVoltaic (PV) generator; ► An Electric Vehicles (EVs) charging station based o n 5 charging points (only charging mode); ► A small residential district powered in AC; ► A connection to a 3 kV DC grid; as sketched in the figure on the right. The DC micr ogrid voltage is kept constant at the value of 500 V. Ratings are reported in the follow: 3 kV DC grid: ► Rated voltage and range, VDC,grid 3 kV ± 20% Residential district: ► Rated AC voltage and range, VAC 400 V ± 10% ► Rated frequency, fn 50 Hz ► Electrical system three-phase, four wire. PV generator: ► Maximum power, PPV 500 kW ► Maximum power point voltage range, VMPP from 600 V to 850 V Charging point (each): ► Battery side voltage range, VBattery from 200 V to 920 V ► Battery side rated current, IBattery 125 A Preliminary Definitions and Calculations 1. Choose the type of DC/DC converter (DC/DC PV) suitable for interfacing the PV generator to the DC microgrid and calculate the minimum and maximum value of the duty cycle. 2. Choose the type of DC/DC converter (DC/DC EV) suitable for interfacing the EVs to the DC microgrid and calculate the minimum and maximum value of the duty cycle. 3. Choose the type of DC/DC converter (DC/DC A) suitable for interfacing the DC microgrid with the 3 kV DC grid and calculate the minimum and maximum value of the duty cycle. 4. Design the layout and define the main ratings of the DC/AC power processor suitable for supply the residential load. For safety reasons, the electrical insulation between the DC input and the AC output must be guaranteed. (continued on next page) PV Generator 3 kV DC…