MPPT Strategy to Improve Photovoltaic Power Generation Efficiency in Partial Shadows

부분 음영에서의 태양광 발전 효율을 높이기 위한 MPPT 전략

Abstract

In order to increase the power generation efficiency of the photovoltaic system, a new algorithm that can follow the maximum power point of the photovoltaic power generation system having nonlinear output characteristics is proposed. Conventional maximum power point tracking (MPPT) algorithms such as Perturbation and Observation (P&O) and InCond (Increment and Conductance) schemes can not find the global maximum power point at a plurality of pole points in the unmatched state of unbalanced PV modules. However, even if the global maximum power point is found at a plurality of pole points, the global maximum power that can not be the real maximum power by the photovoltaic generation system. In order to solve this problem, a few PV companies propose installing several small PV inverters instead of if big one. However, since this will require additional costs, we herein propose a Multi-MPPT system using individual 3-point MPPT to track true MPPT at a plurality of pole points in the unmatched state of unbalanced PV modules.

Fig. 1 An example of the mismatched situation caused by partial shadow in PV array

Fig. 2 The partial shade on a photovoltaic array

Fig. 3 The power from a total photovoltaic array with shade

Fig. 4 Graph of high-mid irradiation (EN50530)

Fig. 5 Algorithm of 3-point MPPT flow chart

Fig. 6 Power of P&O and 3-Point according to high-mid irradiation

Fig. 7 Graph of efficiency of MPPT according to high-mid irradiation

Fig. 8 Multi individual inverters for efficiency

Fig. 9 One inverter with multi boost converters

Fig. 10 Simulation of three boost converters

Fig. 11 Result of Multi-MPPT scheme in mismatched situation

Table 1 Efficiency of MPPT according to high-mid irradiation (Vref Increase)

Table 2 Efficiency of MPPT according to high-mid irradiation (V_ref decrease)

Table 3 Comparison of MPPT in simulation

Table 4 Comparison of MPPT in 12 kW PCS