Three‐phase battery storage system with transformerless cascaded multilevel inverter for distribution grid applications

Abstract

A distributed generator (DG) based on renewable energy is a promising technology for the future of the electrical sector. DGs may benefit utility companies and customers in a variety of perspectives. However, DGs suffer from intermittent behaviour. Storage systems appear as an attractive solution to support the continuous operation of DGs. The technology within the storage also plays an important role, since DGs and storage are connected in medium-voltage grids. The use of batteries and the DC/AC converter in its conventional structure presents drawbacks in such grids. In this context, this study presents a three-phase transformerless battery storage system (BSS) based on a cascaded H-bridge inverter applied to a medium-voltage grid. The BSS is composed of eight equal series connected H-bridge converters, without bulk transformers, for connection to a distribution grid. Each converter contains 75, 12 V/600 Ah lead-acid batteries. The converters are controlled through pulse-width modulation at 600 Hz. The BSS is able to keep working even with a failure of one of its converters. Reactive energy compensation not compensated by an existent passive filter is also performed. A case study with simulated and experimental results obtained through a hardware-in-the-loop system is presented showing the efficacy of the proposed BSS.

Bidirectional DC–DC converter based multilevel battery storage systems for electric vehicle and large‐scale grid applications: A critical review considering different topologies, state‐of‐charge balancing and future trends

“…Selective harmonic elimination PWM (SHE-PWM) is an effective technique to eliminate specific harmonics in CSM-MLCs [37,187,[207][208][209][210][211], however, it is used in other topologies occasionally [138]. Fundamental frequency PWM method improves the efficiency of the system by reducing the effective switching frequency of the converter and it is mostly used in CSM-MLCs [115,157,160,185,190]. Nearest level modulation (NLM) is another technique to enhance the efficiency of the system and finds itself a use in CSM-MLCs [183,195,212].…”

Improved Artificial Neural Network Grid Synchronization Technique for Three-Phase Grid Systems based on Synthesis Segmental Multilevel Converter

“…Here, the efficiency of the suggested inverter was validated with respect to the switching states, and total loss of semiconductor devices. Busarello et al (2017) recommended a three phase Battery Storage System (BSS) for a distributed power grid systems, which was constructed with the help of 8 H-bridge converters. In this model, the Root Mean Square (RMS) value of the voltage and current at output terminal has been calculated for analyzing the detection of failure.…”

Seven‐level power conversion system for solar power generation system

“…Conventionally, each HI in a CHT multilevel power converter requires an independent DC voltage [5][6][7][8][9][10][11]. In the applications of SPGS, the CHT multilevel power converter can be divided into two structures, as shown in Fig.…”

“…Common types of multilevel power converter are cascaded Hbridge type (CHT) [5][6][7][8][9][10][11], flying-capacitor type (FCT) [12,13] and diode-clamped type (DCT) [14,15]. A DCT multilevel power converter uses several series capacitors in the DC bus to create different voltage levels and several clamped diodes are connected between the power electronic arm and these voltage levels.…”

“…However, the voltages in the capacitors for an FCT multilevel power converter should be carefully regulated by redundant switching states of power electronic arms [13]. A CHT multilevel power converter has several H-bridge inverters (HIs) that are connected in series [5][6][7][8][9][10][11]. Asymmetric voltages can be used for HIs in CHT multilevel power converter to increase the number of levels in the AC output voltage [10,11], but this is difficult to implement in DCT and FCT multilevel power converters.…”