INTERCONNECTION FACILITIES STUDY REPORT NORTHEAST WYOMING 250MW GENERATOR Prepared on Behalf of the Transmission Provider: Basin Electric Power Cooperative Transmission Black Hills Power Transmission December 5, 2005
1.0 Executive Summary This is the Generator Interconnection Facilities Study (GIFS) for the Northeast Wyoming 250MW generation (NE WYO) interconnection request submitted by Basin Electric Power Cooperative - Merchant Function. The proposed facility is a 250MW coal fired generating plant located approximately 20 miles north of Gillette Wyoming. Commercial operation is scheduled for January 2011. The purpose of the GIFS is to estimate the cost of equipment, engineering, procurement and construction work needed to physically and electrically interconnect NE WYO. The GIFS will also identify the electrical switching configuration, metering points, switchgear and any other major equipment associated with the Interconnection. An estimated construction schedule associated with Facility Upgrades will also be provided as part of this report. The GIFS is performed in accordance with the Interconnection Facilities Study Agreement (IFSA) dated February 8, 2005, and Section 8 of the Large Generator Interconnection Procedures of the Joint Open Access Transmission Tariff of Black Hills Power, Inc., as Joint Tariff Administrator (Black Hills Power), Basin Electric Power Cooperative, and Powder River Energy Corporation (Joint Tariff). Basin Electric Power Cooperative Merchant Function is the Interconnection Customer and Black Hills Power, Powder River Energy Corporation and Basin Electric Power Cooperative is the Transmission Provider coordinating through the Joint Tariff. The Transmission Provider owns and operates combined transmission facilities referred to as the Common Use System (CUS). A final System Impact Study (SIS) for NE WYO was completed on December 12, 2004. Detailed short-circuit, steady state, and transient stability analysis were performed as part of the SIS. Results of the SIS indicated that two major CUS Network Upgrades must be in-service in order to interconnect NE WYO. The first upgrade consists of a 105 mile 230KV transmission line from Hughes to a new substation in the Sheridan, Wyoming area. This line will be tapped by a new 230KV substation in the vicinity of NE WYO. The second upgrade consists of a 35 mile 230KV transmission line from the NE WYO 230KV substation to the Carr Draw substation. These upgrades, however, are required to meet projected Coal-Bed Methane (CBM) load growth in the NE Wyoming area and therefore will not be associated with NE WYO Network Upgrades, provided that the upgrades are constructed in support of CBM-related loads. Both upgrades will be completed well before the NE WYO in-service date. The transmission line upgrades and location of NE WYO are shown in Figure 4-1 below. Results of the GIFS show that interconnection of NE WYO will require the addition of two 230Kv transmission line terminals at the NE WYO 230KV substation. The total cost for these additions, comprised of Direct Assigned Facilities and Network Upgrades, is $2,420,000. A cost breakdown is provided in Section 6.0 below. 2.0 Introduction This is the Generator Interconnection Facilities Study (GIFS) for the Northeast Wyoming 250MW generation (NE WYO) interconnection request. The proposed facility is a
250MW coal fired generating plant located approximately 20 miles north of Gillette Wyoming with a commercial operation date of January 2011. The short circuit study performed as part of the SIS indicated that there is not a substantial increase in fault duty at area substations. Based on the existing breaker interrupt ratings, the addition of NE WYO requires no breaker upgrades. It is assumed that the Hughes-NE WYO-Sheridan and NE WYO-Carr Draw 230KV lines will be in service prior to the addition of NE WYO. Furthermore, it is assumed that the load shown on the projected CBM load forecast sheets will come to fruition. In the event those facilities are not constructed in support of CBM load, the Interconnection Customer may be required to bear additional costs or financing obligations with respect to facilities required for the interconnection of NE WYO with the Transmission Provider s Transmission System. The costs for modifying the transmission network will be broken out by Direct Assigned Facilities and Network Upgrade Facilities. Direct Assigned Facilities are those facilities or portion of facilities that are required for the sole purpose and benefit of the Interconnection Customer. Network Upgrade Facilities are those transmission facilities that are integrated with and support the Transmission Provider s transmission system for the overall benefit of all users of the system. Results from this study are based on data provided by the Interconnection Customer and other information on the CUS and surrounding transmission system. Any significant changes to transmission development plans or generator data may prompt a restudy. The Interconnection Customer is responsible for providing the Transmission Provider with any significant generator facility design or operational changes. 3.0 CUS Network Upgrade Facilities NE WYO 230KV Substation: A one-line diagram for this substation is provided in Figure 4-2. This substation will support the CBM load growth in the NE Wyoming area as well as provide for a point of interconnection for NE WYO. The substation will be a modified three bay breaker-and-a-half design with five line terminals including a terminal for NE WYO startup power. Network Upgrade Facilities required to support the NE WYO interconnection consists of a new substation bay including two 230KV line terminals. The line terminals include two 230KV/3000 Amp/63KA Gas Circuit Breakers, associated buswork, disconnects, grounding switches, protection systems and any other equipment deemed necessary for the safe and reliable operation of the transmission system. 4.0 Interconnection Customer Facility Requirements The point of interconnection for NE WYO will be the electrical connection between transmission line deadend insulator hardware and the jumper from the transmission line deadend insulator hardware to the substation buswork. The Interconnection Point is shown in Figure 4-2.
Direct Assigned Facilities will include all facilities from the Generator Step-Up (GSU) transformer high side bushing hardware to the point where the radial line jumper connects to the substation busbar. Direct Assigned Facilities include two deadend structures at the GSU and substation respectively, a radial 230KV line, line disconnects, grounding switches, revenue metering, protection systems and any other equipment deemed necessary for the safe and reliable operation of the transmission system. The Transmission Provider will design, procure, construct and own all Direct Assigned Facilities, all at the Interconnection Customer s sole expense. NE WYO will require startup and backup power and therefore, a separate line terminal at the NE WYO substation will be provided, at Interconnection Customer s expense, for startup power. The point of interconnection for NE WYO startup power will be the electrical connection between transmission line deadend insulator hardware and the jumper from the transmission line deadend insulator hardware to the substation buswork. Direct Assigned Facilities include two deadend structures at the startup transformer and substation respectively, a radial 230KV line, line disconnects, grounding switches, revenue metering, protection systems and any other equipment deemed necessary for the safe and reliable operation of the transmission system. The Transmission Provider will design, procure, construct and own all Direct Assigned Facilities, all at the Interconnection Customer s sole expense. A Power System Stabilizer (PSS) will be required on the generator. PSS design and installation shall be coordinated with the Transmission Provider. The generator exciter shall be of the High Initial Response (HIR) type and conform to the latest WECC exciter design criteria. FIGURE 4-1: Transmission System Diagram
To Sheridan WY Area To Hughes N.E. WYO Generator N.E. WYO Generator Back-Up Station Service M Point Of Interconnection M To Carr Draw Figure 4-2: NE WYO 230KV Substation oneline. 5.0 Construction Schedule. Table 5-1 below provides a completion date for major milestones in the construction process. Transmission Provider and Interconnection Customer will coordinate any changes to this schedule. Table 5-1: Construction Schedule TASK Completion Date Start Construction Summer 2007 230kV Line Terminal Additions Winter 2008 Back-Feed Plant Summer 2009 Generator Synch Summer 2010 Generator Testing Summer 2010 Commercial Operation January 2011
The Interconnection Customer must coordinate generator testing with the Transmission Provider and Control Area Operator. 6.0 Network Upgrade and Direct Assigned Cost Estimate Facility costs are broken out between Network Upgrade Facility Costs and Direct Assigned Facility Costs. Direct Assigned Facilities are those facilities or portion of facilities that are required for the sole purpose and benefit of the Interconnection Customer. Network Upgrade Facilities are those transmission facilities that are integrated with and support the Transmission Provider s transmission system for the overall benefit of all users of the system. This cost estimate is a + 20% estimate based on Attachment A to Appendix 4 of the Interconnection Facilities Study Agreement dated February 8, 2005. The actual cost to complete this project can be affected by many factors such as actual construction costs, increases in material costs, increases in labor costs, scheduling and material availability. Network Upgrade Costs: The Network Upgrade Cost estimate is $1,920,000. Facilities included in this cost estimate are provided in Section 3.0 above. Direct Assigned Costs: The Direct Assigned Cost estimate is $500,000. Facilities included in this cost estimate are provided in Section 4.0 above. In addition to the above mentioned costs, the Interconnection Customer will be responsible for an annual fee for the testing and maintenance of the necessary revenue metering equipment. The Interconnection Customer will also be responsible for a monthly operating fee associated with SCADA metering. 7.0 Conclusions Results from the Generator Interconnection Facilities Study (GIFS) indicated that two additional 230KV transmission line terminals at the NE WYO 230KV substation are required in order to interconnect NE WYO. Prior to the NE WYO in-service date, the CUS is expected to add two 230KV transmission lines to support the rapid CBM load growth in NE Wyoming. The first line is from Hughes to the Sheridan Wyoming area with a new substation along this line in the vicinity of NE WYO. The second 230KV line is from the NE WYO 230KV substation to the Carr Draw substation. Based on stability and power flow analysis, these 230KV lines will provide sufficient support for NE WYO. The total cost to interconnect NE WYO to the CUS is $2,420,000. A breakdown of Direct Assigned and Network Upgrade Costs is provided in Section 6.0 above.