Modified Partial-Shading-Tolerant Multi-Input-Single-Output Photovoltaic String Converter

Abstract

Photovoltaic (PV) energy systems rapidly penetrate global renewable energy market recently due to their direct energy conversion, environmental friendly and modularity features. Partial shading and irradiance mismatch create one of the major challenges that face commercial PV converters. Software based maximum power point tracking (MPPT) algorithms show limited performance as only the global peak power of the attached PV string can be captured. On the contrary, modified PV string converters can achieve true MPP acquisition, hence maximizing the system power yield and enhance the overall performance. In this article, a partial-shading-tolerant PV string system is proposed that feature (i) a multi-input multi-output (MISO) PV string converter and (ii) true MPP seeking event-driven based MPPT technique as well. The presented converter feature a single inductor buck configuration with multi-input ports attached to N number of PV panels offering reduced passive components and extended modularity feature in addition to single digital controller implementation. The presented MPPT technique exhibits decoupled tracking of the true power of each connected PV panel independently irrespective of the other attached panels even under extreme inhomogeneous irradiance distribution. Rigorous simulation results accompanying matched experimental validation assure the proposed system applicability. Dynamic modelling, in addition to various operating conditions assessments, verify the claimed effectiveness of the proposed system.

Keywords

• Partial shading
• irradiance mismatch
• global maximum power
• true maximum power
• distributed maximum power tracking
• maximum power point tracking (MPPT)