Wind integration impacts on hydropower and system balancing operations in the Grant County PUD

The Public Utility District No. 2 of Grant County, Washington, USA, in collaboration with the National Renewable Energy Laboratory and Northern Arizona University, conducted an analysis of the impact wind integration on their hydropower dominant generation system. Wind power penetration levels of 12 MW (2.0%), 63.7 MW (10.4%) and 150 MW (24.6%) were considered. For the 2006 study year, a statistical summary of the changes in the regulation and load following requirements expected due to wind variability was conducted. The results demonstrated that the impact of wind power upon minute-to-minute regulation requirements is small, and small to modest on the load following requirements. However, changes in the distribution of load following hourly changes could result in infringement upon system constraints. A chronological simulation of preschedule (i.e. day ahead) planning was therefore conducted indicating an increased incidence of constraint "exceedences." The nature of the increase in exceedences is presented and discussed.