Increasing wind farm transient stability by dynamic reactive compensation: Synchronous-machine-based ESS versus SVC

Using bulk energy storage systems such as pumped-hydro electric storage (PHES) and compressed-air energy storage (CAES) with wind power plants offers advantages. They are well-proven technologies and more economical compared to batteries. Being synchronous machines, apart from the ability to regulate wind farm real power output, they can also be used to provide reactive power to support wind farms, even when their energy storage unit is fully discharged. This paper investigates the use of these ESS to increase wind farms transient stability by dynamic reactive compensation. Experiments with 60-MW wind farm and two types of popular wind turbines, namely stall-controlled and DFIG, show that the ESS performance is better than that of SVC. The ESS are particularly effective for use with stall-controlled wind turbines. They increase the wind farm critical clearing time and shorten the postfault voltage recovery duration considerably. The results suggest an operation technique for raising the ESS efficiency and value.