Asymmetrical Multi-level DC-link Inverter for PV Energy System with Perturb and Observe Based Voltage Regulator and Capacitor Compensator

Abstract

In this paper, a perturb and observe (P&O) based voltage regulator (POVR) and a capacitor compensator (CC) circuit are proposed for the implementation on 31-level asymmetrical switch-diode based multi-level DC-link (MLDCL) inverter. Since the application of MLDCL in a standalone photovoltaic (PV) system requires constant DC voltages from PV panels, the POVR strategy is deployed to regulate the voltage along with the capability to deliver the maximum power at full load. Boost DC-DC converters are used as the interface between the panels and the inverter for the POVR operation. The results show that POVR is capable of achieving the desired fixed DC voltages even under varying environmental and load conditions, with a steady 230 V at the output. At full load, the standalone system successfully delivers 97.21% of the theoretical maximum power. Additionally, CC is incorporated to mitigate voltage spikes at the output when supplying power to inductive loads. It successfully eliminates the spikes and also reduces the total harmonic distortion (THD) of output current and voltage from more than 10% to less than 5%, as recommended in IEEE 519 standard.

Keywords

• Multi-level inverter
• photovoltaic (PV) system
• maximum power point
• voltage regulator
• capacitor compensator (CC)