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

The Korean Institute of Power Electronics (전력전자학회)
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A Study on High-Efficiency MPPT Algorithm Based on P&O Method with Variable Step Size

가변 스텝 사이즈를 적용한 P&O 방식 기반의 고효율 MPPT 알고리즘 연구

  • Kim, Bongsuck (Korea Electric Power Research Institute) ;
  • Ding, Jiajun (Dept. of Electrical Engineering, Chungnam National University) ;
  • Sim, Woosik (Dept. of Electrical Engineering, Chungnam National University) ;
  • Jo, Jongmin (Dept. of Electrical Engineering, Chungnam National University) ;
  • Cha, Hanju (Dept. of Electrical Engineering, Chungnam National University)
  • Received : 2018.08.21
  • Accepted : 2018.10.02
  • Published : 2019.02.20
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Abstract

In this study, a maximum power point tracking (MPPT) algorithm based on the perturb and observe (P&O) method with variable step size is proposed to improve the dynamic response characteristic of MPPT, using the existing P&O method. The proposed algorithm, which we verified by simulation and experiment, can track the maximum power point (MPP) through duty control and consisted of three operation modes, namely, constant voltage mode, fast mode, and variable step mode. When the insolation is constant, the voltage variation of the operating point at the MPP is reduced through the step size reduction of the duty in the variable step mode. Consequently, the vibration of the operating point is reduced, and the power generation efficiency is increased. When the insolation changes, the duty and the photovoltaic (PV) voltage are kept constant through the constant voltage mode. The operating point then rapidly tracks the new MPP through the fast-mode operation at the end of the insolation change. When the MPP is reached, the operation is changed to the variable step mode to reduce the duty step size and track the MPP. The validity of the proposed algorithm is verified by simulation and experiment of a PV system composed of a PV panel and a boost converter.

Keywords

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Fig. 1. Flowchart of MPPT algorithm using P&O method.

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Fig. 2. Flowchart of MPPT algorithm using INC method.

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Fig. 3. Flowchart of the proposed MPPT algorithm.

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Fig. 4. Variation of characteristic curve of PV module and fast mode operation.

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Fig. 5. Possible cases of M according to MPPT operation.

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Fig. 6. Simulation circuit of PV system.

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Fig. 7. Simulation result when MPPT is operating from initial starting point.

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Fig. 8. Simulation results of conventional MPPT method when solar irradiance increases

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Fig. 9. Simulation results of proposed MPPT method when solar irradiance increases.

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Fig. 10. Configuration of experimental equipment.

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Fig. 11. Experimental results when MPPT is operating from initial starting point.

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Fig. 12. Experimental results when solar irradiance decreases.

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Fig. 13. Experimental results when solar irradiance increases.

TABLE 1 PV SIMULATOR PARAMETERS

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TABLE II BOOST CONVERTER PARAMETERS

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