Control Systems for Low-Inertia Power Grids: A Survey on Virtual Power Plants

Abstract

Virtual Power Plants (VPPs) have emerged as a modern real-time energy management architecture that seeks to synergistically coordinate an aggregation of renewable and non-renewable generation systems to overcome some of the fundamental limitations of traditional power grids dominated by synchronous machines. In this survey paper, we review the different existing and emerging feedback control mechanisms and architectures used for the real-time operation of VPPs. In contrast to other works that have mostly focused on the optimal dispatch and economical aspects of VPPs in the hourly and daily time scales, in this paper we focus on the dynamic nature of the system during the faster sub-hourly time scales. The virtual (i.e., software-based) component of a VPP, combined with the power plant (i.e., physics-based) components of the power grid, make VPPs prominent examples of cyber-physical systems, where both continuous-time and discrete-time dynamics play critical roles in the stability and transient properties of the system. We elaborate on this interpretation of VPPs as hybrid dynamical systems, and we further discuss open research problems and potential research directions in feedback control systems that could contribute to the safe development and deployment of autonomous VPPs.INDEX TERMS Smart grids, renewable energy, virtual power plant, feedback control, multi-agent hybrid dynamical systems.

Improving the Efficiency and Reliability of Renewable Energy Systems

“…In the augmentation of the power supply, the requirement for connectivity has often led to the optimization of the distribution system. This distribution is a mode of inquiring about the distribution of practices with respect to the homogenous distribution of power supply [18].…”

Virtual Power Plant with Renewable Energy Sources and Energy Storage Systems for Sustainable Power Grid-Formation, Control Techniques and Demand Response

“…VPP aggregation entails the coordination of different dynamic energies, while ensuring the stability of the overall system. It requires careful design of the VPP control system, as depicted in Figure 8, which integrates the physical and digital layers into a closed-loop system powered by hybrid energy [53]. This framework is used to develop and analyze mathematical models for control design and is often simplified to obtain traditional multivariate linear models for discrete time, continuous time, or hybrid power systems [54].…”

“…This framework is used to develop and analyze mathematical models for control design and is often simplified to obtain traditional multivariate linear models for discrete time, continuous time, or hybrid power systems [54]. To operate the DER and loads effectively in the VPP, we need to develop appropriate control strategies to meet various grid requirements and goals, including regulating and maintaining voltage and frequency stability, fault management, synchronization, and realtime optimization [53]. These goals are defined according to the VPP hierarchy and must comply with local standards or protocols.…”

Estratégias de controle para resposta em frequência na operação isolada entre geração eólica offshore e plataformas de óleo e gás em águas profundas.

“…Desta forma, o SG mantém o sincronismo e evita o colapso ou apagão da rede. A massa rotativa do gerador contribui com energia cinética para a rede ou a absorve da rede sob variações de frequência [46].…”

“…Quando existe uma variação de frequência mais elevada e certos limites técnicos de operação são ultrapassados, há a possibilidade de serem ativados outros mecanismos de contenção, com o objetivo de estabilizar e recuperar a frequência após um evento [46,58]. Este tipo de controle de frequência é comumente dividido entre reservas de contenção (ou FCR -do inglês, Frequency Containment Reserve) e reservas de restauração de frequência (ou FRR -do inglês, Frequency Restoration Reserve), de forma equivalente, entre controles primário e secundário, respectivamente [59], conforme apresentado na Figura 8.…”