Sliding mode controller for extraction and supply of photovoltaic power using switched series parallel sources reduced switch count multilevel inverter

Abstract

Abstract The reduced switch count multilevel inverter (RSC‐MLI) is the latest trend in power electronic converters due to reduction in the switch count and cost. However, a large number of RSC‐MLIs have not yet reached to the application level because of the absence of modularity, unequal load‐sharing among DC sources and the absence of switching redundancies. On the other hand, multilevel dc‐link (MLDCL) and switched series parallel sources (SSPS) RSC‐MLI topologies are modular structures with adequate switching redundancies and can be an alternative to conventional cascaded H‐bridge (CHB) for grid‐connected photovoltaic (PV) systems. Therefore, in this paper, a comprehensive comparison among CHB, MLDCL and SSPS topologies has been carried out for grid connected PV application. Based on the outcome, an asymmetric 11 kV three‐phase 11‐level SSPS RSC‐MLI is chosen. In this combination, a common non‐linear sliding mode controller (SMC) is developed for generating maximum PV power from asymmetric single‐stage PV sources by linearizing the non‐linear PV system using an effective feedback linearization scheme. The PV power extracted is delivered to the grid by controlling SSPS RSC‐MLI using another SMC. The performance of the system under wide variations of insolation levels is verified in MATLAB and further validated in hardware‐in‐the‐loop OPAL‐RT controller.

Keywords

• Solar power stations and photovoltaic power systems
• Control of electric power systems
• DC‐DC power convertors
• DC‐AC power convertors (invertors)
• Multivariable control systems