*Article* **Modular Multilevel Converter for Photovoltaic Application with High Energy Yield under Uneven Irradiance**

#### **Anirudh Budnar Acharya 1,\*, Dezso Sera 2, Remus Teodorescu 1 and Lars Einar Norum 3**


Received: 3 April 2020; Accepted: 18 May 2020; Published: 21 May 2020

**Abstract:** The direct integration of Photovoltaic (PV) to the three-phase Modular Multilevel Converter (MMC) without *dc–dc* converters results in high-efficiency PV power plant with increased energy yield. The arm power control method for the MMC further improves the extraction of available power under uneven irradiance across different phases of the MMC. However, the uneven irradiance between the sub-modules results in residual voltage that results in harmonics and unbalance components. In this paper, the effect of uneven irradiance across the sub-module of the MMC is investigated with arm power control method. A modified balancing algorithm for the arm power control of the MMC is proposed which enables balanced power to be injected into *ac* grid despite uneven irradiance across the sub-modules in the MMC. The modified balancing algorithm enables to keep the unbalance in the phase currents below 10% and the Total Harmonic Distortion (THD) is confined as per IEEE 519 standard.

**Keywords:** modular multilevel converter; photovoltaic power system; grid integration; control system; distributed renewable energy source
