All SiC Grid-Connected PV Supply with HF Link MPPT Converter: System Design Methodology and Development of a 20 kHz, 25 kVA Prototype

Abstract

Design methodology and implementation of an all SiC power semiconductor-based, grid-connected multi-string photovoltaic (PV) supply with an isolated high frequency (HF) link maximum power point tracker (MPPT) have been described. This system configuration makes possible the use of a simple and reliable two-level voltage source inverter (VSI) topology for grid connection, owing to the galvanic isolation provided by the HF transformer. This topology provides a viable alternative to the commonly used non-isolated PV supplies equipped with Si-based boost MPPT converters cascaded with relatively more complex inverter topologies, at competitive efficiency figures and a higher power density. A 20 kHz, 25 kVA prototype system was designed based on the dynamic model of the multi-string PV panels obtained from field tests. Design parameters such as input DC link capacitance, switching frequencies of MPPT converter and voltage source inverter, size and performance of HF transformer with nanocrystalline core, DC link voltage, and LCL filter of the VSI were optimized in view of the site dependent parameters such as the variation ranges of solar insolation, module surface temperature, and grid voltage. A modified synchronous reference frame control was implemented in the VSI by applying the grid voltage feedforward to the reference voltages in abc axes directly, so that zero-sequence components of grid voltages are taken into account in the case of an unbalanced grid. The system was implemented and the proposed design methodology verified satisfactorily in the field on a roof-mounted 23.7 kW multi-string PV system.

Applications of Power Electronics

“…Photovoltaic (PV) applications, as they utilize renewable energy resources to reduce the carbon footprint, are being employed more and more for distributed power generation. Applying the power electronics technique for PV application is the main focus in [35][36][37], covering different design aspects. While [35] addresses the practical implementation of a three-level boost converter using FPGA, in [36], the importance of using wide band-gap devices such as silicon carbide (SiC) to achieve better performance and power density is addressed.…”

“…Applying the power electronics technique for PV application is the main focus in [35][36][37], covering different design aspects. While [35] addresses the practical implementation of a three-level boost converter using FPGA, in [36], the importance of using wide band-gap devices such as silicon carbide (SiC) to achieve better performance and power density is addressed. Lastly, the application of a modular multi-level converter (MMC) based on a cascaded connection is described in [37] for PV applications.…”

Design of a Building-Integrated Photovoltaic System with a Novel Bi-Reflector PV System (BRPVS) and Optimal Control Mechanism: An Experimental Study

“…As capacitor does not allow DC current to pass through it, steady-state load current i(t) and DC component (I) of rectifier input current are equal expressed by Equation (4).…”

“…However, the lower efficiency and higher initial cost make BIPV less practical and difficult to commercialize. Dye-Sensitized Solar Cells (DSSCs) have attracted considerable attention in recent years because of their simple assembly, lightweight, flexibility, economical price of materials, satisfactory photocurrent transformation efficiency, precise energy return time, and tunable optical properties [4]. On the other hand, DSSCs have power conversion efficiency of more than 14% with a limited active area; the output power decreases with increasing cell effective area of the photoanode [5].…”

Equivalent Circuit Model for Cu(In,Ga)Se2 Solar Cells Operating at Different Temperatures and Irradiance

“…In Equation (1), V and I stand for cell output voltage and current, respectively. Although this circuital model might seem simple, it is able to describe accurately the current-voltage behavior of different PV cell technologies [19] and can be used for several interesting PV-related applications, such as irradiance measurement [26,27], device degradation assessment [28] and maximum power point tracking [29][30][31][32][33]. As stated before, the main problem in the use of this circuital model is the extraction of its parameters from measured current-voltage curves.…”