Novel Quantification Method of Aggregated Energy Flexibility Based on Power-Duration Curves

Abstract

Energy flexibility aggregation is an emerging concept regarded as a potential solution to the challenges of integrating distributed renewable energy sources. For aggregators to make informed decisions on how to utilise the energy flexibility of prosumers in their portfolios, it is crucial for them to use a suitable quantification method. This paper proposes a novel quantification method for aggregated energy flexibility based on flexibility curves created from the relationship between flexible power and its sustained duration. The proposed method also considers the asymmetric and non-linear properties of energy flexibility. The flexibility curves provide valuable insights for aggregators to make informed decisions on how to utilise their portfolios in a more optimal manner. We describe the quantification method with a step-by-step process. A simulation-based case study is conducted to illustrate the quantification process of residential heating systems. The aggregated flexibility curves and the rebound effects of 1000 different heat-pump-based buildings are constructed. The building’s thermal behaviour is modelled using a resistive-capacitive model. We found that the power at which the flexibility can be activated highly depends on the activation duration. Additionally, the rebound effect can be quite substantial, with around 1.8 times the energy of the activation itself. We also noted an interesting phenomenon of rebound overshooting as the system oscillates to a stable position.

Keywords

• Aggregation
• energy flexibility
• heating system
• rebound effect
• quantification