ABSTRACT
During the period from the early 1970s to the late 1980s, wind turbines (WTs) were too small to impact the operation, protection, and control of power systems. Because of wind variability and poor predictability, wind energy was not considered a significant factor in power system planning or unit commitment. Thus, their presence was unnoticed by most utilities. Curtailing wind farms and compensating owners for the loss of generation was an acceptable practice when problem occurs. For example, when wind farms caused voltage fluctuations at the generator step-up (GSU) transformers, they were curtailed. When reactive power fluctuations or reactive power demands were severe, wind farms were curtailed. When the transmission capacity at certain times could not support the variability of wind production, wind farms were curtailed. When faults occur in power system, WTs were allowed to disconnect from the grid.
