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Solar radiation forecasting by time series models

시계열 모형을 활용한 일사량 예측 연구

  • Suh, Yu Min (Department of Applied Statistics, Chung-Ang University) ;
  • Son, Heung-goo (Korea Power Exchange) ;
  • Kim, Sahm (Department of Applied Statistics, Chung-Ang University)
  • Received : 2018.10.25
  • Accepted : 2018.12.11
  • Published : 2018.12.31

Abstract

With the development of renewable energy sector, the importance of solar energy is continuously increasing. Solar radiation forecasting is essential to accurately solar power generation forecasting. In this paper, we used time series models (ARIMA, ARIMAX, seasonal ARIMA, seasonal ARIMAX, ARIMA GARCH, ARIMAX-GARCH, seasonal ARIMA-GARCH, seasonal ARIMAX-GARCH). We compared the performance of the models using mean absolute error and root mean square error. According to the performance of the models without exogenous variables, the Seasonal ARIMA-GARCH model showed better performance model considering the problem of heteroscedasticity. However, when the exogenous variables were considered, the ARIMAX model showed the best forecasting accuracy.

신재생에너지 산업이 발전함에 따라 태양광 발전에 대한 중요성이 확대되고 있다. 태양광 발전량을 정확히 예측하기 위해서는 일사량 예측이 필수적이다. 본 논문에서는 태양광 패널이 존재하는 청주와 광주 지역을 선정하여 기상포털에서 제공하는 시간별 기상 데이터를 수집하여 연구하였다. 일사량 예측을 위하여 시계열 모형인 ARIMA, ARIMAX, seasonal ARIMA, seasonal ARIMAX, ARIMA-GARCH, ARIMAX-GARCH, seasonal ARIMA-GARCH, seasonal ARIMAX-GARCH 모형을 비교하였다. 본 연구에서는 모형의 예측 성능을 비교하고자 mean absolute error와 root mean square error를 사용하였다. 모형들의 예측 성능 비교 결과 일사량만 고려하였을 때는 이분산 문제를 고려한 seasonal ARIMA-GARCH 모형이 우수한 성능을 나타냈고, 외생변수를 활용한 ARIMAX 모형으로 일사량 예측을 한 경우가 가장 좋은 예측력을 나타냈다.

Keywords

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Figure 3.1. Hourly solar radiation of Cheongju and Gwangju in 2015.

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Figure 3.2. Hourly solar radiation of Cheongju and Gwangju in January 2015.

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Figure 3.3. Result of forecasting 7-Days ahead, ARIMA model.

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Figure 3.4. Correlation of Cheongju and Gwangju.

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Figure 3.5. Result of forecasting 7-Days ahead, ARIMAX model. ARIMAX = auto-regressive integrated moving average with eXogenous variable.

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Figure 3.6. Result of Forecasting 7-Days ahead, seasonal ARIMA model. ARIMA = auto-regressive integratedmoving average.

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Figure 3.7. Result of forecasting 7-Days ahead, seasonal ARIMAX model. ARIMAX = auto-regressive integrated moving average with eXogenous variable.

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Figure 3.8. Result of forecasting 7-Days ahead, ARIMA-GARCH model. ARIMA = auto-regressive integrated moving average; GARCH = generalized auto-regressive conditionally heteroscadastic.

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Figure 3.9. Result of forecasting 7-Days ahead, ARIMAX-GARCH model. ARIMAX = auto-regressive integrated moving average with eXogenous variable; GARCH = generalized auto-regressive conditionally heteroscadastic.

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Figure 3.10. Result of forecasting 7-Days ahead, seasonal ARIMA-GARCH model. ARIMA = auto-regressive integrated moving average; GARCH = generalized auto-regressive conditionally heteroscadastic.

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Figure 3.11. Result of forecasting 7-Days ahead, seasonal ARIMAX-GARCH model. ARIMAX = auto-regressive integrated moving average with eXogenous variable; GARCH = generalized auto-regressive conditionally heteroscadastic.

Table 3.1. Fitted models using ARIMA

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Table 3.2. Result of variable selection using ARIMAX model

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Table 3.3. Fitted models using ARIMAX

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Table 3.4. Fitted models using seasonal ARIMA

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Table 3.5. Fitted models using seasonal ARIMAX

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Table 3.6. Model comparison

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Table 3.7. Model comparison of peak hour using mean absolute percentage error

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