New Control Scheme for Solar Power Systems under Varying Solar Radiation and Partial Shading Conditions

Anindya-Sundar Jana,Chang-Hua Lin,Shiue-Der Lu,Hwa-Dong Liu

doi:10.3390/pr9081359

Abstract

The traditional perturbation and observation (P&O) maximum power point tracking (MPPT) algorithm of a structure is simple and low-cost. However, the P&O algorithm is prone to divergence under solar radiation when the latter varies rapidly and the P&O algorithm cannot track the maximum power point (MPP) under partial shading conditions (PSCs). This study proposes an algorithm from the P&O algorithm combined with the solar radiation value detection scheme, where the solar radiation value detection is based on the solar photovoltaic (SPV) module equivalent conductance threshold control (CTC). While the proposed algorithm can immediately judge solar radiation, it also has suitable control strategies to achieve the high efficiency of MPPT especially for the rapid change in solar radiation and PSCs. In the actual test of the proposed algorithm and the P&O algorithm, the MPPT efficiency of the proposed algorithm could reach 99% under solar radiation, which varies rapidly, and under PSCs. However, in the P&O algorithm, the MPPT efficiency was 96% under solar radiation, which varies rapidly, while the MPPT efficiency was only 80% under PSCs. Furthermore, in verifying the experimental results, the proposed algorithm’s performance was higher than the P&O algorithm.

Highlights

On rainy or cloudy days, solar radiation is under 150 W/m2 and the solar power generation (SPG) system output power is low [1]
The perturbation and observation (P&O) algorithm, whose structure is simple and low-cost, is the most frequently used [17]. It has four disadvantages: (1) while it cannot track the MPP under partial shading, this algorithm could converge to the local peak power point (LPPP) and cause a lower system performance [18]; (2) with the P&O algorithm’s actuating point close to the maximum power point (MPP), it converges slowly [19]; (3) this algorithm’s actuating point oscillates near the MPP when solar radiation is steady, causing low system efficiency [19,20]; (4) the P&O algorithm is prone to divergence when solar radiation varies quickly [20,21]
The present study proposes a new control scheme for the SPG system where the solar radiation value detection scheme is the solar photovoltaic (SPV) module equivalent conductance (Rspv−1) threshold control (CTC) implemented in the maximum power point tracking (MPPT) control scheme, combined with the P&O algorithm

Summary

Introduction

On rainy or cloudy days, solar radiation is under 150 W/m2 and the solar power generation (SPG) system output power is low [1]. The P&O algorithm, whose structure is simple and low-cost, is the most frequently used [17] It has four disadvantages: (1) while it cannot track the MPP under partial shading, this algorithm could converge to the local peak power point (LPPP) and cause a lower system performance [18]; (2) with the P&O algorithm’s actuating point close to the maximum power point (MPP), it converges slowly [19]; (3) this algorithm’s actuating point oscillates near the MPP when solar radiation is steady, causing low system efficiency [19,20]; (4) the P&O algorithm is prone to divergence when solar radiation varies quickly [20,21]. The proposed algorithm efficiency is higher than the P&O algorithm, which could operate at the MPP and avoid being trapped in the LPPP under PSCs

Perturbation and Observation Algorithm

Proposed Algorithm

Conclusions