The 345kV Sweetwater IV substation was constructed for Pattern Energy (formerly Babcock & Brown) in 2006. The substation was constructed to directly tie a 135-megawatt wind farm to a new 345kV transmission line that was constructed under the same contract as the substation. The high side of the yard was constructed to accommodate an additional 80.5-megawatt wind farm that was tied in shortly thereafter. The substation has two main power step-up transformers and associated 34.5kV bus and breakers with a manual intertie between the low side bus. The substation is also designed and constructed to control both wind farms’ reactive power compensation.