Modeling of energy transactions and ancillary services for dynamic security assessment

In light of the regulatory changes witnessed by the power industry, there is a need to model power system operations under separate agreements for energy and for transmission and ancillary services. A new modeling method to help the operating authority evaluate the necessary ancillary services for ensuring system security and reliability is proposed. For a given set of energy transactions, this study demonstrates the impact of the type, amount and location of ancillary services on the system\´s dynamic performance. We focus on services that could impact dynamic security: reactive supply and voltage control from generation sources, frequency response, and regulation. The implications of "dynamic transfers", i.e., provision of regulation services to individual loads across control area boundaries, are also investigated. The models used capture fast generator exciter dynamics as well as slower governor, load, and automatic generation control responses. The proposed method is validated on a three-area, nine-machine, 28-bus system.