Islanding experience at a petroleum processing cogeneration facility

This paper examines the control of combustion turbine generators to maintain stability when transitioning from interconnected operation to islanded operation. Specifically, the paper describes an Isochronous operating scheme to regulate the system frequency along with load sharing for maintaining stability during islanded operation of a cogeneration power plant at a petroleum processing facility in Abqaiq, Saudi Arabia. All aspects of the solution are discussed. Simulations of dynamic performance of the plant for a number of islanding scenarios are described. The paper discusses simulation and evaluation of a number of possible control schemes, and provides a description of the scheme that was ultimately selected for implementation at the site. The paper also describes the staged site testing program, starting with testing to validate the models used in dynamic simulations and concluding with demonstration of the control scheme via a full plant islanding tests. Data from the test program is presented along with comparisons to simulations.