Grid code requirements for artificial inertia control systems in the New Zealand power system

Wind turbines and gas turbines inherently have a low or non-existent connected inertia. With a growing demand for wind generation and the connection of more gas turbines, a decrease in the amount of system inertia is being experienced in the New Zealand power system and could possibly pose a large threat to other islanded systems. When a large generator is lost within a low inertial system, the frequency will fall significantly faster than in a system with higher inertial response. This results in more market costs to the New Zealand power system because more spinning reserve is procured to boost the overall inertial response and allow governors time to respond. Dynamic analysis was used to analyze the effects of lowering the inertia on the reserve market and a minimum inertial response required from generators has been calculated. This allowed a grid code standard to be established. A method of incentivizing generators to build higher inertia generators is also discussed.