Statistical Correlation Study of Temperature Humidity Index (THI) and Load in the ERCOT System

The recent development of high-penetration renewable energy resources requires better control and projection of electrical demand since renewables are non-dispatchable. While there are numerous methods for load forecasting, there is a lack of tools to study the load under extreme heat waves from a long-term planning perspective. In this paper, the correlation between a weather-related index called Temperature Humidity Index (THI) and load in the ERCOT system is studied. First, this paper outlines the methods for calculating THI and creating a piecewise linear regression model. Then, a standardized approach to data processing is provided. Next, the correlation of THI and load in the ERCOT system is analyzed and verified. Finally, the paper is concluded with general observations and discussions of other factors affecting THI-load correlation like economic or population growth. The results show that the THI versus load model is a promising tool for projecting load under extreme summer drought conditions.