Final System Impact Study for. Sierra Pacific Industries 31 MW Generation Project. Mount Vernon, WA. November 16, 2006

Transcription

1 Final System Impact Study for Sierra Pacific Industries 31 MW Generation Project Mount Vernon, WA November 16, 2006 Puget Sound Energy, Inc. Electric Transmission Department 1

2 1. Introduction On October 6, 2005, Sierra Pacific Industries (Sierra) and Puget Sound Energy (PSE) executed an Interconnection System Impact Study (SIS) Agreement for Sierra s proposed 31 MW BioMass fueled generating facility at the Fredonia Business Park near Mt. Vernon. Sierra had previously submitted a request for Network Resource Interconnection Service on July 19, The expected commercial operating date is December 31, It was determined that a System Impact Study (the Study ) would be required to evaluate the impact of the Requested Service on PSE s Transmission System. The Study would determine if there were any system constraints and identify re-dispatch options, additional Direct Assignment Facilities or Network Upgrades required to provide the Requested Service. Power flow simulation studies were performed in compliance with PSE and NERC/WECC Planning Standards. The proposed location is adjacent to PSE s Fredonia Generation Station which is rated for approximately 120 MW interconnected at the 115kV level. To the east of the proposed location are two oil refineries and a second, approximately 140 MW generating plant, owned by March Point. The Fredonia area is connected to the main grid by the Sedro Woolley - Texaco East 115kV line which interconnects to the 230kV system to east at the Sedro Woolley substation and to the west at the March Point substation southeast of the Texaco East substation (see Figure 1). Skagit County generation, along with generation in Whatcom County to the north, affects and is affected by imports and exports on the Westside Northern Intertie (WSNI) between the United States and Canada. The WSNI, where flow is measured on the two 500kV lines between BC Hydro s Ingledow Substation near Vancouver, B.C., and BPA s Custer Substation near Ferndale, WA, is jointly operated by BPA and BC Hydro. PSE has WSNI ownership rights contractually defined with BPA. Figure 1: Existing System 2

3 2. Conclusion The Study concluded that the Requested Service of 31 MW can be accommodated with upgrades to PSE facilities in Skagit County. As defined by the SIS requirements, these improvements would allow all resources in addition to the project to be delivered to the network at peak loading. Under light summer load conditions generation in the Fredonia and March Point area may be constrained due to limits on the Sedro Woolley-Texaco East 115kV line to the east of the project. A possible solution is to uprate the thermal conductor rating of the line from 55 deg C to 75 deg line. In addition, under certain light loading conditions or abnormal system configurations, generating resources in Whatcom and Skagit Counties, including the Sierra project, may be constrained from delivering full output to network loads south of Skagit County. For the study the project was interconnected to the Sedro Woolley Texaco East 115 kv line with a new four breaker substation with a ring bus layout. The existing Wilson Tap line was also terminated on the ring bus. Other possible interconnection configurations, including moving the new breakers to PSE s Fredonia substation are possible and would produce similar results. Costs for transmission interconnection facilities and transmission improvements are estimated at $3 to 4 million. 3. Study Criteria and Assumptions The Study incorporated existing planning and operating criteria, standards, and procedures in conformance with NERC/WECC Planning Standards in order to determine necessary Transmission 3

4 System reinforcements and re-dispatch requirements. Single and common mode outages for all PSE facilities and critical WSNI facilities were used for the analysis. The Study included a number of individual summer and winter power flow simulation studies to determine the existing system s capabilities and the impacts of the project. The power flow simulation studies were conducted with the following assumptions, goals and limitations: Assumptions Assume the proposed Sierra project will be running as of January 1, Assume all existing PSE generation in Whatcom and Skagit Counties is on line. Assume the full WECC accepted path rating for the Northwest-Canada Path #3, where flow is measured on the two 500kV lines between BC Hydro s Ingledow Substation near Vancouver, B.C., and BPA s Custer Substation near Ferndale, WA. For north to south flow (import) the limit is 2850 MW and for south to north flow (export) the limit is 2000 MW. Assume all equipment is in service and then run contingency analysis to determine system impacts. Goals Identify constraints on PSE s transmission systems in Skagit and Whatcom Counties and any network upgrades necessary to integrate the project. Study Limitations Pursuant to PSE s Large Generator Interconnection Procedure (LGIP), the Study will determine whether, with the Large Generating Facility at full output, the aggregate of generation in the local area can be delivered to the aggregate of load on Transmission Provider's Transmission System. In addition, the LGIP states that Network Resource Interconnection Service does not necessarily provide Interconnection Customer with the capability to physically deliver the output of its Large Generating Facility to any particular load on Transmission Provider's Transmission System without incurring congestion costs. Studies were run to determine the ability of the Skagit and Whatcom County System to deliver the aggregate generation under peak winter, peak summer and light summer loading. PSE s ability to deliver the aggregate generation in these counties, including the Sierra project, to loads south of Skagit County can be constrained dependant on loading and generation levels. Studies were done using the light summer season base case to determine the risk level of local light load constraints. The summer season is one of the most restrictive and highly stressed times of year for the transmission system. This is when equipment ratings (capabilities) are at or near their minimums, the WSNI is being maximized often on import and export and when the Puget Sound area loads, including loads in the area of the proposed generation, are at their lowest. This sensitivity demonstrates the robustness of the local system and provides a measure of the risk of potential local constraints. Furthermore, contingencies are taken with all lines in service or system normal. Operational conditions where facilities are out of service due to planned maintenance or construction or unplanned outages are 4

5 not part of the Study. There could be operational conditions that would impact generation levels due to lower transmission capabilities within the Skagit system. 4. Study Conditions Several base cases were used in the Study. The majority of the studies were conducted using modified versions of WECC winter and summer 2006 operating cases. The cases were modified to reflect 2007/2008 system loads. PSE loads were grown to PSE forecasted levels, except customer-owned substation loads, which were held constant. Snohomish PUD, Tacoma City Light and Seattle City light loads were grown at 1% per year. In the light load cases, PSE loads were at 60% of the heavy load cases with industrial load levels held constant. Post contingency line loadings which changed by less than 1% were considered insensitive to the project. The contingencies included Puget Sound Area common mode failures as well as all single contingency events in the Puget Sound Area. The common mode contingencies are listed in Appendix A. 5. Power Flow Study Results The study had the proposed Sierra Pacific generation connected to the main grid by looping the Sedro Woolley-Texaco East 115kV line into a new substation at the Sierra site. If the project goes forward in this configuration, PSE would likely route its Wilson Tap into the proposed station (see Figure 2). The system modeled was based on a four breaker ring bus configuration. Transformation from 115kV to 230kV in Skagit County is located at PSE s Sedro Woolley to the east and March Point Substation to the west. Power flow depends on generation and load levels in Skagit County. Figure 2: Proposed Interconnection: 5

6 Contingency studies were run on the existing system and with the Sierra Project at 31 MWs. The Study found that the existing system would support the addition of the proposed generation at the Sierra facility. No overloads were found for either the heavy winter or heavy summer load cases thus meeting the Network Resource Interconnection requirements. For the heavy winter and summer cases run only the heavy summer export case resulted in facilities loading above 95% of their rating as noted in Table 1. For the light summer cases several overloads appeared in the analysis as shown in Table 2. The worst overloads occurred when exporting the full 2000 MW on the WSNI. In Whatcom County, the most limiting outage for the combined high export and high PSE Whatcom/Skagit generation scenario is the loss of the BPA Custer BPA Bellingham and BPA Custer PSE Sedro BPA Murray double circuit 230kV lines. The limiting facility is the PSE Portal Way 230/115kV transformer. As shown in the table the overload increases from 117.1% to 119% and loading increases as well on the 115kV system near Portal Way. In operating the system this constraint can result in limiting the south to north export capability of the WSNI to avoid overloads. However, in practice the combination of light summer loading, heavy exports to Canada (which in the summer typically correspond to low power costs) and high PSE thermal generation is highly unlikely. In addition, as previously discussed, light summer loading is also when network generating resources in Whatcom and Skagit Counties, including the Sierra project, may be constrained. In Skagit County, overloads occurred for two low probability outages: the open ending of the Sedro Woolley-Fredonia-March Point 230kV line at Sedro Woolley, and the failure of the south 115kV bus sectionalizing breaker at March Point substation. Under light load conditions excess generation in the Fredonia and March Point areas flow back to Sedro Woolley from March Point on the 230kV transmission line. Both of the above outages result in the loss of the 230kV interconnection between March Point and Sedro Woolley resulting in excess generation flowing back on the 115kV system and increasing the west to east flow on the Texaco East-Sedro Woolley 115kV. In the case of the open ending 6

7 of the 230kV line at Sedro Woolley, this excess generation includes the 200 MW of Fredonia generation connected to the 230kV line now radially connected to March Point. While the March Point breaker failure does not force the 230kV generation onto the 115kV system, it is more severe due to the loss of load in the Anacortes area combined with the Texaco East-Sedro Woolley 115kV line being the only remaining 115kV tie between March Point and Sedro Woolley following the contingency. With the addition of the Sierra Pacific project these flows increase on the Sedro side of the project. These overloads could be mitigated by uprating the 12.2 miles of the Texaco East-Sedro Woolley 115kV transmission line east of the proposed project from a 55C conductor temperature rating to a 75C rating. 7

8 Table 1 - HS08 Export Branch Violations 08HS3SA: EXPORT 2000, PSE WHA/SKA GEN=1236 MW, SCL SKA GEN=471 MW, SNOH GEN=85 MW FROM 2008 HS CASE ContMVA = MVA flow on element following contingency BaseFlow = MVA flow on element with no contingencies Loading% = ContMVA/Rating Branches with MVA flow more than 95.0 % of nominal rating Reaults with SIERRA PAC=0MW Reaults with SIERRA PAC=31MW Contingency From bus To bus CKT ContMVA BaseFlow Rating Loading% ContMVA BaseFlow Rating Loading% DC CUS-SED-MUR & CUS-BHM 230KV CUSTER W 230 PORTALWY DC CUS-SED-MUR & CUS-BHM 230KV PORTALWY 115 ARCO C FREDONIA 230 TO SEDRO OLYBAYTP 115 WILSN TP

9 Table 2 - LS08 Export Branch Violations 08LS1P: EXPORT 2000, PSE WHA/SKA GEN=1236 MW, SCL SKA GEN=178 MW, SNOH GEN=115 MW FROM 2006 LS OP CASE ContMVA = MVA flow on element following contingency BaseFlow = MVA flow on element with no contingencies Loading% = ContMVA/Rating Branches with MVA flow more than 95.0 % of nominal rating Reaults with SIERRA PAC=0MW Reaults with SIERRA PAC=31MW Contingency From bus To bus CKT ContMVA BaseFlow Rating Loading% ContMVABaseFlow Rating Loading% DC CUS-SED-MUR & CUS-BHM 230KV CUSTER W 230 PORTALWY DC CUS-SED-MUR & CUS-BHM 230KV PORTALWY 115 ARCO C DC CUS-SED-MUR & CUS-BHM 230KV CAROLINA 115 ENTRPRIS DC CUS-SED-MUR & CUS-BHM 230KV LYNDEN 115 PORTALWY DC CUS-SED-MUR & CUS-BHM 230KV VISTA P 115 ENTRPRIS BHM 230KV BUS CUSTER W 230 PORTALWY FREDONIA 230 TO SEDRO OLYBAYTP 115 WILSN TP FREDONIA 230 TO SEDRO OLYBAYTP 115 AVON PMP FREDONIA 230 TO SEDRO AVON PMP 115 BURLIGTN FREDONIA 230 TO SEDRO RITA P 115 BURLIGTN FREDONIA 230 TO SEDRO SEDRO 115 RITA P MARPT S 115 BUS BKR OLYBAYTP 115 WILSN TP MARPT S 115 BUS BKR OLYBAYTP 115 AVON PMP MARPT S 115 BUS BKR AVON PMP 115 BURLIGTN MARPT S 115 BUS BKR RITA P 115 BURLIGTN MARPT S 115 BUS BKR SEDRO 115 RITA P

10 6. Stability Study Results Three stability studies were performed. To check PSS performance a 3 cycle fault was applied to the Custer W 500kV bus with no line clearing. To check performance for extended faults, two faults with breaker failures were analyzed. The first was a 3-phase fault on the Baker Sw-Sedro Woolley 115kV line with normal (6 cycle) clearing at Baker Sw but a stuck breaker at Sedro Woolley requiring clearing by the breaker failure relay (15 cycles). The second was a 3-phase fault on the Texaco W-Texaco E 115kV line with normal (6 cycle) clearing at Texaco W but a stuck breaker at Texaco E requiring clearing by the breaker failure relay (15 cycles). Performance was stable and damped as shown in Figures 1-3 below. Figure 1: PSS test with 3 cycle fault at Custer W 500kV bus Rotor Angle, Voltage and PSS output at Sierra Pacific 10

11 Figure 2: Fault on Baker-Sedro #2 115kV line with a stuck breaker at Sedro with 15 cycle clearing Fredonia and Sierra Pacific Rotor Angles and Fredonia Voltage (P.U.) 11

12 Figure 3: Fault on Texaco West Texaco East #1 115kV line with a stuck breaker at Texaco East with 15 cycle clearing Fredonia and Sierra Pacific Rotor Angles and Fredonia Voltage (P.U.) 12

13 7. Costs Transmission costs for improvements to connect the proposed 31 MW of generation at the Sierra Pacific include the following: Project: Cost x 1,000 Construct new four breaker ring bus substation on customer site $3,000 Total $3,000 Total with 30% contingency buffer $3,900 13

14 Appendix A BKF 4268 MONROE #1-CUSTER-CUSTER TX 1 BKF 4272 Custer, Ingledow1-Custer-Monroe1 500-kV BKF 4276 INGLEDOW #1-CUSTER-CUSTER TX 2 BKF 4482 INGLEDOW #1-CUSTER-CUSTER TX 1 BKF 4486 Custer W, Ingledow2-Custer-Custer TXF kV BKF 4494 Custer W, Monroe2-Custer-Custer TXF kV BKF 4496 MONROE #2-CUSTER-CUSTER TX 2 BKF 4526 Monroe, Echo Lake(3T)-Monroe2-Custer 500-kV BKF 4672 Monroe, Cheif Joe-Monroe-Monroe CapsG2 500-kV BKF 5053 Monroe, Monroe 500/230-kV TXF & Caps G2 BKF 5075 Echo Lake, Echo Lake-Schultz1 & Echo Lake CapsG1&2 BKF 5111 Echo Lake, Monroe-Echo Lake-Echo Lake CapsG1&2 500-kV BKF 5114 Echo Lake, Raver-Echo Lake-Monroe 500-kV BKF 5121 Echo Lake, Echo Lake-Maple Valley & Echo Lake CapsG1&2 BKF A1238 Custer, Bellingham-Custer-Intalco1 230-kV BKF A1242 Custer, Custer TXF1-Custer-Intalco1 230-kV BKF A1246 Custer, Custer TXF1-Custer-Portal Way 230-kV BKF A1250 Custer, Murray-Custer-Intalco2 230-kV BKF A1254 Custer, Custer TXF2-Custer-Bellingham 230-kV BKF A1428, Monroe 230-kV, fault on Horse R. Tap line BKF A1540 Custer, Murray-Custer-Portal Way 230-kV BKF A1546 Custer, Custer TXF2-Custer-Intalco2 230-kV BKF Murray 230-kV fault on Murray-Sedro-Custer(3T) BKF Tenaska-Terrell-OlyARCO 115-kV Bus Portal Way N 115 kv Bus Portal Way S 115 kv BKF Portal Way Bus Section 115 kv Bus PSE ARCO N 115-kV Bus PSE ARCO C 115-kV Bus PSE ARCO S 115-kV Bus BPA Bellingham 115-kV Bus BPA Bellingham 230-kV Bus PSE Bellingham E 115-kV Bus PSE Bellingham W 115-kV BKF PSE Bellingham Bus Section 115 kv Bus Sedro Woolley W 115 kv Bus Sedro Woolley C 115 kv Bus Sedro Woolley E 115 kv BKF Sedro Woolley W Bus Section 115 kv BKF Sedro Woolley E Bus Section 115 kv Bus March Point N 115 kv Bus March Point C 115 kv Bus March Point S 115 kv BKF March Point N Bus Section 115 kv BKF March Point S Bus Section 115 kv Bus MONROE 230-kV Bus MURRAY 115-kV Bus MURRAY 230-kV Bus Snohomish 230-kV Sect. 1 14

15 Bus Snohomish 230-kV Sect. 2 Bus Snohomish 230-kV Sect. 3 Bus Snohomish 230-kV Sect. 4 BKF Snohomish 230-kV Sect. 4, fault on Snoh-HR-Monroe 230-kV (3T) Bus SnoKing 230-kV Middle Sect. 2 Bus SnoKing 230-kV North Sect. 1 Bus SnoKing 230-kV South Sect. 3 DC MAPLE VAL-SNOKING #1 & #2 230-kV CRW CHIEF JO-MONROE 500 & CHIEF JO-SNOHOMISH 345 #3 (13) CRW CHIEF JO-MONROE 500 & CHIEF JO-SNOHOMISH 345 #4 (252) CRW CUSTER-INGLEDOW 1&2 (69) CRW CUSTER-MONROE 1&2 (N-S FLOW) (26) CRW ECHO LAKE-MAPLE VALLEY 500 & ROCKY REACH-MAPLE VALLEY 345 (93) CRW MONROE-CUSTER #1 500 & CHIEF JO-SNOHOMISH #4 (244) CRW MURRAY-CUST & BHAM-CUST (59) Monroe-Snoking-Echo Lake 500-kV (3T) Murray-Sedro-Custer W 230-kV (3T) N-2: Chief Joe-Snohomish #3 & #4 345-kV BKF 3153 Sedro, Sedro-Fredonia-March Pt. (3T) & Sedro-Custer-Murray (3T) 230-kV BKF 3159 Sedro, Sedro-Bellingham 230-kV & Sedro 230/115-kV TXF BKF 7023 Horse Ranch 230-kV Bus Sammamish 230-kV East Sect. Bus Sammamish 230-kV West Sect. BKF 52 Sammamish, fault on Klahanie line 230-kV CRW MURRAY-CUST & BHAM-SEDRO DC SAMM-M VAL & SAMM-MONROE 230 BKF Maple Valley 230-kV fault on Klahanie line Bus Maple Valley 230-kV Sect. 1 & 2 Bus Maple Valley 230-kV Sect. 3 N-2: Snohomish-Bothell #1 & #2 230-kV Bus Talbot Hill 115-kV Sect. 1 Bus Talbot Hill 115-kV Sect. 2 Bus Talbot Hill 230-kV North Sect. Bus Talbot Hill 230-kV South Sect. Sedro-Horse Ranch-Bothell 230-kV (3T) BKF Bothell 230-kV Sect. 5 fault on Sedro-Both-HRanch (3T) DC BOTH-SAMM & SEDRO-BOTH-H RANCH 230-kV Bus Bothell 230-kV Sect. 1 Bus Bothell 230-kV Sect. 2 Bus Bothell 230-kV Sect. 3 Bus Bothell 230-kV Sect. 4 Bus Bothell 230-kV Sect. 7 DC Bothell-Snohomish #2 230-kV & Bothell-Diablo #3 230-kV DC BOTHELL-SNOKING #1 & #2 230-kV 15