Power Generation Load Sharing Using Droop Control in an Island System

A crude oil production and shipping terminal was built and expanded over time such that the facility was powered by three isolated power systems. These separate plants have since been interconnected to permit the sharing of generation reserves. Initially, the interconnected system was supervised by a power management system (PMS) that relied on isochronous operation of one power plant for frequency control. The PMS attempted to implement system wide load sharing by issuing raise and lower speed and voltage signals to the second power plant, which was operated in droop control. Due to a variety of factors, this control proved unsatisfactory. The control strategy was revised to operate all generators in droop mode and to handle management of frequency, voltage, and power flows between plants at the secondary control level. This paper describes why the initial PMS was unsatisfactory, why it was abandoned, and how it was modified to enable the successful interconnection of all three power plants into a single network.