Variable energy resource induced power system imbalances: Mitigation by increased system flexibility, spinning reserves and regulation

The impact of variable energy resources (VER) on power system reserve and regulation requirements has been a subject of extensive research in recent years. However, the conclusions about the scale of the impact diverge, since most of the results are obtained from specific case studies. This paper proposes a generalized approach to the assessment of power system reserve and regulation requirements. It uses a power system enterprise model that consists of three layers: the physical grid, resource scheduling and balancing operations. Resource scheduling is modeled as a security-constrained unit-commitment (SCUC) problem. The balancing layer consists of three components, namely the regulation service, the real-time market and operator manual actions. The real-time market is implemented as a security-constrained economic dispatch (SCED) problem. The IEEE RTS96 reliability test system is used for the physical layer. Three main resources contributing to the balancing of power system are studied: reserves, regulation and generator ramping rates. Their impacts on power system imbalance mitigation in the presence of VER is studied.