Utilities plan additions to the transmission and distribution facilities they own that meet their customers’ needs and make sense for their shareholders. Because the grid is interconnected, major additions must be coordinated not only with neighboring utilities but with all utilities in the region, even if the new facilities are located in only one state. Interstate projects must also be planned in ways that support the reliability of the entire grid.
Utilities in every geographic region of the West have formed voluntary Sub-Regional Planning Groups (SPGs) to coordinate this planning. Each Sub-Regional Planning Group maintains a website with information about major projects proposed in its region and the studies being performed to evaluate those projects.
• California Independent System Operator (CAISOCalifornia Independent System Operator www.caiso.com): http://www.caiso.com/.
The CAISO plans and operates the transmission system covering about 70% of California, including the transmission facilities owned by Pacific Gas & Electric, Southern California Edison, and San Diego Gas & Electric. It is one of only two Regional Transmission Organizations (RTOs) in the Western InterconnectionThe Western Interconnection is one of the two major alternating current (AC) power grids in North America. The other major wide area synchronous grid is the Eastern Interconnection. The three minor interconnections are the Québec Interconnection, the Texas Interconnection, and the Alaska Interconnection. All of the electric utilities in the Western Interconnection are electrically tied together during normal system conditions and operate at a synchronized frequency operating at an average of 60Hz. The Western Interconnection stretches from Western Canada South to Baja California in Mexico, reaching eastward over the Rockies to the Great Plains. Interconnections can be tied to each other via high-voltage direct current power transmission lines (DC ties), or with variable frequency transformers (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side. The Western Interconnection is tied to the Eastern Interconnection with six DC ties. It is not tied to the Alaska Interconnection. (the other is the Alberta Electric System Operator). Municipal utilities plan, own and operate transmission in the remainder of the state.
• Sierra Subregional Planning Group (SSPGSierra Subregional Planning Group): www.westconnect.com/planning_sierra.php
• Southwest Area Transmission (SWATSouthwest Area Transmission (Subregional Planning Group for AZ-NM, southern portions of Nevada, Utah and Colorado)): www.westconnect.com/planning_swat.php
SWAT covers AZ, NM, southern NV and a small portion of southeastern CA. The many work groups shown on the website address projects in specific geographic areas or special transmission problems.
• Colorado Coordinated Planning Group (CCPGColorado Coordinated Planning Group): www.westconnect.com/planning_ccpg.php
• Northern Tier Transmission Group (NTTGNorthern Tier Transmission Group www.nttg.biz): www.nttg.biz/site
The NTTG footprint includes UT, WY, MT, ID, OR and a small portion of WA.
• Columbia Grid: www.columbiagrid.org
The Columbia Grid footprint includes WA, OR, ID, and a small area of MT.
• British Columbia Transmission Corporation (BCTC): http://transmission.bchydro.com/home
• Alberta Electric System Operator (AESO): http://www.aeso.ca/
At the request of the Western Electricity Coordinating Council (WECCWestern Electricity Coordinating Council), these Sub-Regional Planning Groups have also recently formed a Subregional Coordination Group (SCG) to coordinate planning across the seams among them.
For an excellent PDF of frequently asked questions – go HERE on WECC’s site.