Frequency Control in an Isolated Power System with High Renewable Energy Penetration

Isolated power systems have traditionally used diesel generation to ensure reliable and stable power. Due to the high costs of purchasing and transporting diesel fuel to remote areas, these communities have been integrating renewable energy sources such as wind and solar to reduce reliance on diesel and decrease operating costs. When there is enough renewable energy to supply the load diesel engines can be turned off completely. This decreases fuel consumption but introduces stability problems due to the lack of spinning reserves and inertia. Energy storage systems can be used effectively for frequency control but are still very expensive. Therefore, some isolated power systems will limit the acceptance of renewables in order to keep diesel engines online for frequency control. This paper investigates the use of a dump load and enhanced frequency response techniques for wind turbines as methods for frequency control to facilitate 100% acceptance of renewable energy. Results showed that a dump load was sufficient for frequency control and kept frequency within 0.3 Hz of nominal frequency. Advanced wind turbine control systems were found to only slightly improve the frequency response by 0.03 Hz.