Fault detection technique for modified cascaded half-bridge multi-level inverter with polarity changer in pv grid system

Abstract

Multilevel Inverters (MLI) are a viable option for a filter-less and transformerless photovoltaic system for direct grid integration, reducing losses, space and cost provided the issues of control and reliability are resolved. A modified cascaded half-bridge MLI with polarity changer is proposed with a reduced number of switches, thereby reducing control complexity. The proposed converter is designed for both seven-level and nine-level topologies. Selective harmonic elimination has been adopted to switch converter and the transcendental equations are solved by the gravitational search algorithm. The THD for nine-level configuration is 7.94% and 5.86% with MPPT and DC source inputs, respectively. The analysis on the open-circuit fault of switches confirms the presence of only five critical switches irrespective of the number of increase in levels, thereby requiring only five redundant switches at the Polarity Changer. The output voltage waveform is subjected to multiresolution analysis for feature extraction of voltages under various irradiance and temperature conditions. A conditions based fault detection algorithm is developed based on the observations of energies of signals to detect the open circuit fault in switches. Based on the comparative analysis, the proposed converter has fewer controlled switches for nine levels or higher configurations than other topologies. Apart from this, the high reliability due to inherent fault isolation capability restricted to half-bridge compared to different MLI topologies shows its superiority. For a nine-level MLI proposed topology reduces the cost considering redundancies for FDI in range of 67–30% depending on the topology for comparision. The system is simulated using MATLAB –Simulink and further validated by experimental results.

Reliable speed control of a separately excited DC motor using advanced modified triple modular redundancy scheme in H-bridges

“…It also discusses the transient response, sliding process, and sliding surface, as well as its benefits and drawbacks. H-Bridges multi-level inverter with polarization converter offers superior dependability as mentioned in Vyas et al 17 and less complication than another redundant multi-level inverter due to the lower total amount of regulated relays. In this research, a backup switching is necessary to remove the damaged switches, and this switch is referred to as a crucial switch.…”