Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
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A Study on the Efficiency Improvement Method of Photovoltaic System Using DC-DC Voltage Regulator

DC-DC 전압 레귤레이터를 이용한 태양광전원의 효율향상 방안에 관한 연구

  • Tae, Donghyun (Dept. of Electrical Engineering, Korea University of Technology & Education) ;
  • Park, Jaebum (Dept. of Electrical Engineering, Korea University of Technology & Education) ;
  • Kim, Miyoung (Dept. of Electrical Engineering, Korea University of Technology & Education) ;
  • Choi, Sungsik (Dept. of Electrical Engineering, Korea University of Technology & Education) ;
  • Kim, Chanhyeok (Dept. of Electrical Engineering, Korea University of Technology & Education) ;
  • Rho, Daeseok (Dept. of Electrical Engineering, Korea University of Technology & Education)
  • 태동현 (한국기술교육대 전기전자통신공학부) ;
  • 박재범 (한국기술교육대 전기전자통신공학부) ;
  • 김미영 (한국기술교육대 전기전자통신공학부) ;
  • 최성식 (한국기술교육대 전기전자통신공학부) ;
  • 김찬혁 (한국기술교육대 전기전자통신공학부) ;
  • 노대석 (한국기술교육대 전기전자통신공학부)
  • Received : 2016.04.15
  • Accepted : 2016.07.07
  • Published : 2016.07.31
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Abstract

Recently, the installation of photovoltaic (PV) systems has been increasing due to the worldwide interest in eco-friendly and infinitely abundant solar energy. However, the output power of PV systems is highly influenced by the surrounding environment. For instance, a string of PV systems composed of modules in series may become inoperable under cloudy conditions or when in the shade of a building. In other words, under these conditions, the existing control method of PV systems does not allow the string to be operated in the normal way, because its output voltage is lower than the operating range of the grid connected inverter. In order to overcome this problem, we propose a new control method using a DC-DC voltage regulator which can compensate for the voltage of each string in the PV system. Also, based on the PSIM S/W, we model the DC-DC voltage regulator with constant voltage control & MPPT (Maximum Power Point Tracking) control functions and 3-Phase grid connected inverter with PLL (Phase-Locked Loop) control function. From the simulation results, it is confirmed that the present control method can improve the operating efficiency of PV systems by compensating for the fluctuation of the voltage of the strings caused by the surrounding conditions.

최근, 전 세계적으로 신재생에너지에 대한 관심이 증가됨에 따라 친환경적이고 무한한 태양에너지를 이용하는 태양광전원의 설치가 급증하고 있다. 이러한 태양광전원은 주변 환경에 따라 출력이 크게 좌우되는데, 예를 들어 구름 또는 건물의 음영으로 인한 일부 모듈의 문제로 인해서 해당 스트링이 출력을 발생하지 못할 수 있다. 즉 기존의 제어방식에서는 모듈이 직렬로 연결된 스트링이 인버터에 연계되어 있으므로, 일부 모듈에 음영이 발생할 경우 스트링의 전압이 인버터의 동작전압 미만으로 되어 해당 스트링이 인버터에서 탈락되는 문제점이 발생할 수 있다. 따라서 본 논문에서는 각각의 스트링마다 전압을 제어하는 DC-DC 전압 레귤레이터를 이용하여, 스트링이 인버터에서 탈락되는 문제점을 개선하는 새로운 태양광전원 제어방식을 제안하였다. 또한, 회로해석 상용 프로그램인 PSIM S/W를 이용하여, 정전압 제어 및 MPPT(Maximum Power Point Tracking) 제어기능을 가지는 DC-DC 전압 레귤레이터와 위상동기루프(PLL, Phase-Locked Loop) 제어 기반의 3상 인버터의 모델링을 수행하였다. 이 모델링을 바탕으로 시뮬레이션을 수행한 결과, 부분적으로 음영이 발생하는 모듈을 가진 스트링이 인버터에서 탈락하는 현상을 개선함으로써 태양광전원의 운용효율이 향상됨을 확인하였다.

Keywords

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