A New Medium Voltage DC Collection Grid for Large Scale PV Power Plants with SiC Devices
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© 2018 IEEE. In this paper, a new medium voltage DC collection grid method for large-scale PV plants is proposed. An Interleaved Modular Multilevel (IMMC) DC-DC boost converter is proposed in order to enable medium voltage DC power collection grid followed by a central medium voltage class DC-AC inverter for utility interface. The proposed IMMC converter is synthesized with lower voltage half-bridge SiC inverter blocks connected in series to support medium voltage DC conversion. The half-bridge blocks of the IMMC employ SiC switches, along with high frequency PWM operation enable compact size/weight along with high efficiency conversion. Simulation results are shown for 1500V (DC) to 16kV (DC) conversion with four series connected IMMC inverter blocks powered from two PV plants. A power sharing stage is an integral part of the proposed converter. This enable two series connected PV plants to supply unequal power under partial shading conditions. Control of the power sharing stage for varying insolation from PV (1000-500W/m2) due to shading effect is shown. A design example for 1MW PV power plant block based on the specifications derived from Kuwait Shagaya 60MW solar power plant is discussed. Experimental results on scale down laboratory prototype is included in the paper.
author list (cited authors)
Alhuwaishel, F., Allehyani, A., Al-Obaidi, S., & Enjeti, P.