Quantification of Power System Flexibility: A Review

Traditional power system operations rely on controllable fossil fuel-based generators to meet unanticipated changes in electricity demand and contingencies. However, high penetration of Renewable Energy Sources (RES), especially solar and wind, increases randomness in the netload. This intermittency leads to inaccurate netload prediction and loadgeneration imbalances. Power systems with a high share ofRES require additional operational flexibility to cope with supplydemand mismatches. While flexibility can be enhanced using various measures, system operators need to quantify its requirements and availability in the system to ensure smooth real-time operations. Recent literature presents various methods for flexibility quantification. To consolidate various works presented in the domain, this paper presents a detailed literature review on flexibility quantification methods. Based on the mathematical formulation, the literature is classified into 1) Deterministic and 2) Probabilistic approaches. Further, the work highlights the challenges of each quantification method. Finally, this paper highlights the impact of flexible resource failure on power system operations and emphasizes the need to consider reliability of resources in the quantification methods.