Extending the Input Voltage Range of Solar PV Inverters with Supercapacitor Energy Circulation

Abstract

Cleaner and greener energy sources have proliferated on a worldwide basis, creating distributed energy systems. Given the unreliable nature of the renewable sources such as solar and wind, they are traditionally based on inverters interfaced with legacy AC grid systems. While efficiency, output waveform quality and other technical specifications of inverters keep improving gradually, only limited attention is given to widening the input range of inverters. This paper presents a new supercapacitor assisted (SCA) technique to widen the input range of an inverter without modifying the inverter itself. Developing a prototype version of a 24 V DC input capable supercapacitor-assisted wide input (SCASWI) inverter using a supercapacitor circulation front end and a commercial 12 V DC line frequency inverter is detailed in the article, explaining how the SCASWI inverter technique doubles the input voltage while maintaining the useful characteristics of the commercial inverter. The new technique has the added advantage of DC-UPS capability based on a long-life supercapacitor module.

Supercapacitor-Assisted Techniques and Supercapacitor-Assisted Loss Management Concept: New Design Approaches to Change the Roadmap of Power Conversion Systems

“…The SCALoM theory is an extension of the traditional textbook Resistor-Capacitor (RC) circuit theory with the aim of achieving higher charging efficiency in the charging loop using the advantage of the large time constant of a supercapacitor combined with a useful resistive load in the loop. Starting from the traditional RC theory, the fundamental background of this theory is described in three stages (Sections 4.1-4.3) as follows [54]:…”

“…The SCA-submodule inverter (SCASMI) technique [48,54] is another collaborative research project with the target of achieving high-performance inverters based on the same SCALoM theory, for more effective harnessing of renewable energy. The SCA DC circuit breaker (SCA-DCB) is yet another such development, aimed at solving a major issue faced by the DC Microgrids, recognizing the fundamental issue of a DC loop compared to 50 Hz/60 Hz utility power waveforms, where two zero crossings per AC cycle help in the design of a cost-effective circuit breaker.…”

A Current Differential Protection Scheme for Distribution Networks with Inverter-Interfaced Distributed Generators Considering Delay Behaviors of Sequence Component Extractors

“…An increasing variety of distributed generations (DGs) are being incorporated into modern medium-voltage DNs. The high-level proliferation of DGs, especially inverter-interfaced distributed generators (IIDGs), enables the DNs to be green and sustainable [1,2]. However, grid-connected IIDGs that are significantly different to the traditional synchronous generators [3][4][5] dramatically exacerbate the complexity of the grid operation and fault levels [6,7], which change the topologies and fault characteristics of the DNs.…”