AY 2021 22 Test 1 Numerical part with solutions

Page 1

ELECTRIC CONVERSION FROM GREEN SOURCES OF ENERGY Prof. Alberto Dolara 1 ©Prof. Alberto Dolara – All rights reserverd Numerical exercise 1 < 28 June 2022 > A hybrid generat ing system is based on a Photovoltaic (PV) generator and a Battery Energy Storage System (BESS), as shown in the picture on the right. Ratings are reported in the follow: Inverter A: ► Rated power, PINV-A,n 50 0 kW ► DC Input voltage range, Vd,INV-A,n from 7 00 V to 1000 V Inverter B: ► Rated power, PINV-B,n 200 kW ► DC Input voltage range, Vd,INV-B,n from 250 V to 350 V Transformer nameplate: Rated frequency fn 50 Hz Vector group Dyy11 High voltage winding Nominal apparent power SMVn 600 kVA Nominal voltage 1 (line-to-line) VMVn 15 kV Low voltage winding 1 Nominal apparent power SLV1n 500 kVA Nominal voltage 1 (line-to-line) VLV1n 400 V Low voltage winding 2 Nominal apparent power SLV2n 200 kVA Nominal voltage 2 (line-to-line) VLV2n 150 V Short circuit tests (MV to LV1) Short circuit active power Pcc_MV-LV1 3100 W Short circuit voltage vcc_MV-LV1 4.5 % Short circuit tests (MV to LV2) Short circuit active power Pcc_MV-LV2 850 W Short circuit voltage vcc_MV-LV2 3.5 % Short circuit tests (LV1 to LV2) Short circuit active power Pcc_LV1-LV2 600 W Short circuit voltage vcc_LV1-LV2 3.0 % Open circuit test Open circuit active power P0 2800 W Open circuit power factor cos(ϕ0) 0.2 Preliminary Definitions and Calculations 1. Calculate the parameters of the per-phase transformer equivalent circuit referred to the Medium Voltage (MV) side. (continued on next page) BESS PV Generator Inverter B Inverter A Grid Trafo LV1 LV2 MV 2 ©Prof. Alberto Dolara – All rights reserverd Assume the following operating conditions: ► PV voltage, VPV 815 V ► PV power, PPV 350 kW ► BESS voltage, VBESS 308 V ► BESS power, PBESS 75 kW…