Electric energy system planning considering chronological renewable generation variability and uncertainty

The increasing integration of renewables poses great challenges to the power system planning problem, especially, the power outputs of renewable generation show the inherent characteristics of long- and short-term chronological variability and uncertainty, which puts higher requirements on the flexibility of the planning strategy. While incorporating unit commitment (UC) constraints considering reserve capacity into planning models has been widely investigated to address renewable energy generation volatility, the re-dispatch of generation units to balance short-term forecasting errors in renewable energy is generally ignored. In this paper, we propose a novel expansion planning model that integrates operational flexibility constraints (EP-OFLX). This model aims to address both long- and short-term chronological variability and uncertainty, optimizing investment decisions for both generation and transmission facilities to achieve the desired level of renewable energy penetration. These constraints include clustered unit commitment constraints to accommodate the variability of renewables and robust re-dispatch operating constraints to handle the uncertainty of renewable generation. A case study is conducted on a modified IEEE RTS-79 system to demonstrate the effectiveness of the proposed method and verify the scalability of the EP-OFLX model. Additionally, the impacts of renewable uncertainty on flexible resource planning are analyzed.