The Transactions of the Korean Institute of Power Electronics (전력전자학회논문지)

The Korean Institute of Power Electronics (전력전자학회)
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Optimum MPPT Control Period for Actual Insolation Condition

실제 일사량 조건에서의 최적 MPPT 제어주기

  • Ryu, Danbi (Dept. of Electrical, Electronic and Control Eng., Kongju National University) ;
  • Kim, Yong-Jung (Dept. of Electrical, Electronic and Control Eng., Kongju National University) ;
  • Kim, Hyosung (Div. of Electrical, Electronic and Control Eng., Kongju National University)
  • Received : 2018.09.21
  • Accepted : 2018.10.23
  • Published : 2019.04.20
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Abstract

Solar power generation systems require maximum power point tracking (MPPT) control to acquire maximum power using inefficient and high-cost PV modules. Most conventional MPPT algorithms are based on the slope-tracking concept. The perturb and observe (P&O) algorithm is a typical slope-tracking method. The two factors that determine the MPPT performance of P&O algorithm are the MPPT control period and the magnitude of the perturbation voltage. The MPPT controller quickly moves to the new maximum power point at insolation change when the perturbation voltage is set to large, and the error of output power will be huge in the steady state even when insolation is not changing. The dynamics of the MPPT controller can be accelerated even though the perturbation voltage is set to small when the MPPT control period is set to short. However, too short MPPT control period does not improve MPPT performance but consumes the MPPT controller resources. Therefore, analyzing the performance of the MPPT controller is necessary for actual insolation conditions in real weather environment to determine the optimum MPPT control period and the magnitude of the perturbation voltage. This study proposes an optimum MPPT control period that maximizes MPPT efficiency by measuring and analyzing actual insolation profiles in typical clear and cloudy weather in central Korea.

Keywords

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Fig. 1. 9-hour insolation profile at Cheonan-city in central Korea.

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Fig. 2. Peak-cut value estimation way of PV module power generation according to MPPT control period.

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Fig. 3. Comparison of MPPT control period and MPPT efficiency characteristics by the peak-cut estimation method.

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Fig. 4. Concept of the amount of power generated in the PV module during ideal MPPT control.

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Fig. 5. Diode equivalent circuit of PV module.

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Fig. 6. PV model built by MATLAB.

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Fig. 7. P-V characteristic curve by PV modeling.

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Fig. 8. Analysis of Relationship between MPPT period and estimated MPPT Efficiency by detailed estimation method.

TABLE I ELECTRICAL SPECIFICATIONS OF THE PV MODULE USED IN MEASUREMENT

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TABLE II ACCUMULATED INSOLATION ACCORDING TO WEATHER

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TABLE III MPPT EFFICIENCY BY THE PEAK-CUT WAY

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TABLE IV ELECTRICAL SPECIFICATION OF PV MODULE APPLIED TO SIMULATION

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TABLE V ELECTRICAL SPECIFICATION OF PV MODULE APPLIED TO SIMULATION

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References

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