SASKPOWER OPEN ACCESS TRANSMISSION TARIFF

SASKPOWER OPEN ACCESS TRANSMISSION TARIFFATTACHMENT DMethodology for Completing a System Impact StudyPurposeThe purpose of the document is to describe the SaskPower study practices ormethodology used for completing a system impact study under the terms of SaskPower’s OATT.Overview of the SaskPower SystemThe SaskPower transmission system is characterized by relatively long 230 kV and 138 kVtransmission lines connecting 10 existing generating stations to sparsely distributed load supplypoints. The existing network resources consist of coal-fired generators, combined cycle andsimple cycle gas fired generators and hydro generators. Historically, the most economic dispatchhas been to use the coal generation and combined cycle generation as base load with the hydrounits used to track the load shape. Simple cycle gas fired generation has been used mainly forpeak shaving. The load on the SaskPower system load peaks in winter, due to increased heatingand lighting requirements. The annual load factor is about 70%.Tie lines provide three interfaces with other systems; two with the MAPP system and one withthe WSCC system. These interfaces, particularly those with North Dakota and Alberta, wereoriginally planned primarily to facilitate generation reserve sharing and seasonal diversityagreements with neighboring utilities, based on a low capacity factor. In addition to the previousreserve sharing benefits, the Manitoba interface also provides mutual system reinforcementbenefits that improve stability and reduce losses. Although all the interfaces are controlled,transfer capability over the Manitoba and North Dakota interfaces are dependent on simultaneousPage | 114