Virtual power plants offering energy and flexible ramping products in real-time electricity markets

Abstract

Fossil fuels are becoming extinct and environmental concerns are increasing. Hence, power systems are now developing distributed energy resources (DER) in power distribution networks—most DERs are renewable. However, a major challenge for system integration of DERs is how to manage and control a large amount of DERs. One feasible solution is aggregating many types of DERs into a virtual power plant (VPP) and creating a single operating profile such that they can be observed and controlled by system operators. In market environments, the primary objective of a VPP is to provide efficient offers and maximize the profit in electricity markets. Although the offering strategy of VPPs in forward electricity markets (e.g., day-ahead electricity markets) has been well studied, the strategy in real-time electricity markets is generally unclear. For flexibility concerns in real-time operations, many independent system operators (ISO) have implemented markets with flexible ramping products (FRP) to aid system-wide ramping capabilities and accommodate the net load change in the future. The thesis investigates the offering strategies for energy and FRPs that VPPs offer in real-time electricity markets. It commences with a review of preliminary concepts such as VPPs, electricity markets, and FRPs. Next, the thesis presents a price-based operation model for VPP that is a basis for determining efficient offering strategies. Further, this thesis proposes a look-ahead offering strategy for energy in real-time electricity markets using the multi-stage stochastic programming formulation. By the proposed look-ahead model, the VPP can yield offer curves continuously in real-time market operation. This thesis also discusses a few offering strategies of VPPs for energy and ramping capacities that can be used for real-time market clearing. These strategies yield energy and FRP production for VPPs in every market interval. Finally, this thesis presents concluding remarks on the investigations conducted and point out some future research directions.