Frequency control and regulating reserves by VPPs

The virtual power plant (VPP) is a paradigm that aggregates widely dispersed resources over an electrical grid or part of it thereof and aspires to emulate the behavior of conventional generators. In this sense, VPPs are expected to contribute to system services. One of the most typical and important system services is frequency control. Frequency control ensures the continuous balance of generation and demand and acts so to preserve it in real-time as imbalances occur. To realize this service, proper reserves, defined as regulating reserves, must be procured and retained to respond to any imbalance during a given planning time-frame. As VPPs comprise multiple different resources, which are dispersed over potentially vast areas, procuring regulating reserves and realizing frequency control is a challenging task. This chapter defines frequency control as a service offered by VPPs, and also illustrates the ways this service may be planned and realized.