Manage Real-Time Power Imbalance With Renewable Energy: Fast Generation Dispatch or Adaptive Frequency Regulation?

The carbon neutrality objective requires a large amount of renewable energy integrated into power systems. The rapid deployment of variable renewable energy (VRE), such as solar photovoltaic (PV) generation, increases the system real-time power imbalance because of the random variation and uncertainty of VRE power generation. To manage this, system operators have two potential options: the first is a fast real-time generation dispatch to schedule generation resources with a small time interval to promptly follow the change of load and renewable power. The second is to procure adaptive frequency regulation services, such as secondary frequency regulation (SFR), based on the system variation and imbalance conditions to reduce the power imbalance and maintain the stable intra-interval frequency. This paper proposes an integrated alternating current optimal power flow-based generation scheduling and time domain simulation framework to investigate the economic and reliability perspectives of aforementioned two options. The impacts of the SFR requirements on the generation cost and frequency response performance are analyzed. In addition, the SFR provided by the PV generation is investigated. The uncertainty of the PV power output is considered using chance constraints to guarantee the real-time delivery of its frequency regulation services. The framework is tested in the IEEE 39-bus network with a large-scale PV power plant. The simulation results demonstrate that the small real-time generation dispatch interval does not necessarily improve the system frequency response and cannot maintain stable frequency. An adaptive frequency regulation with a 5-minute economic dispatch interval is more appropriate and efficient to reduce the generation cost and improve the frequency response with renewable energy.