2009 Scenario Reliability Assessment - NERC

Scenario Reliability Self-AssessmentsOverviewThe Scenario Case was constructed to examine the impacts of 15 percent renewables penetrationin the Western Interconnection in 2017. Because of the limitations on the specific analysis andstudy construction, some of the impacts are not apparent from the study itself, but are knownfrom other studies and activities that are being undertaken by WECC and other parties in theWestern Interconnection.The basic scenario study builds off two studies that were done by TEPPC: 109 a base case studythat was done to examine the transmission planning impacts of meeting existing statutory RPS inthe Western Interconnection (which yielded a renewables penetration of 8.8 percent) and thescenario study that increased the renewables penetration to 15 percent.Because the two studies were designed to meet loads, there are no direct reliability impactsdemonstrated by the studies. There are, however, operational impacts of high levels of variablegeneration that make up the bulk of the renewables in the study, and are known from otherstudies. These are described later in the report, along with the work being done by WECC andothers in the Western Interconnection to address them, and prevent them from becomingreliability problems.The following assumptions were used to develop the 2017 study data for the 2008 TEPPC Studyplan.109 http://www.wecc.biz/documents/library/TEPPC/2009/CoverLetter_Exec_Summary_Final_V4_a.pdf2009 Scenario Reliability Assessment Page 159