Current stress and switching loss evaluation of a unified expandable power converter used for grid‐integration of renewable energy sources

Abstract

Due to the intermittent nature of the renewable energy systems (RESs), more specifically, solar panels and wind turbines, their sole use does not lead to a smooth and reliable power. To overcome this issue, the concurrent grid-integration of RESs to form a microgrid is reported. In the DC-bus microgrid, the produced power by RES is initially given to the shared DC-bus through an individual source-side converter and then transmitted to the utility via a common grid-side converter. By increasing the number of RESs, the number of required power converters, and therefore, the investment cost also increase. Using the cost-effective multi-input low-switch converters is a promising alternative to alleviate this significant need for individual converters. Recently, a nine-switch-based unified expandable power converter (UEPC) has been presented for concurrent integration of AC and DC sources with a tangible fewer switch count. This unified structure has been utilized in two configurations named AC-AC-AC and AC-AC-DC. In this paper, both configurations are evaluated and compared in terms of current stress and switching loss. Considering the current stress analysis, the best port for interfacing with the grid to lower the total current rating of power switching devices is also determined. The high-performance capability of both configurations is finally verified using MATLAB/Simulink.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

A novel multiport converter switching scheme to integrate multiple renewable energy sources

“…In a conventional structure for RESs' grid integration, where each source has an individual converter, this requirement can be achieved regardless of the converter's switching method. The conventional power converter topologies used in integrating RESs can be classified broadly into two categories: the AC bus‐ and DC bus‐based schemes, as demonstrated in Figure 1A,B, respectively 6 …”

“…As an accepted alternative way, the use of unified AC MPCs such as nine‐switch and multileg converters can reduce the number of switching devices, 18,19 hence the system's cost in ASDs and grid integration of RESs. These converters can be also used in integrating distributed energy resources (DERs) with the AC power grid, which can eventually help in building a low‐cost microgrid 6,20 . However, due to shared switches and leg in these converters, the autonomous control of the sources/loads highly depends on the switching method.…”

“…A sequential SVM for independent control of the rotor‐ and stator‐side windings of a dual mechanical port‐based hybrid electric vehicle using a five‐leg converter is developed in Bizhani et al 40 In the sequential SVM, the switching time is divided between outputs with respect to their needs. The autonomous control of the outputs is guaranteed by sequential SVM, although due to the partial assignment of DC link between outputs, the DC voltage utilization is poor 6 …”

“…The conventional power converter topologies used in integrating RESs can be classified broadly into two categories: the AC bus-and DC bus-based schemes, as demonstrated in Figure 1A,B, respectively. 6 As can be seen, by increasing the number of sources, the number of required switches and, therefore, the installation cost increase significantly. This triggers the research in the direction of the multiport converters (MPCs).…”

“…These converters can be also used in integrating distributed energy resources (DERs) with the AC power grid, which can eventually help in building a low-cost microgrid. 6,20 However, due to shared switches and leg in these converters, the autonomous control of the sources/loads highly depends on the switching method. The…”