TRANSMISSION AND SUBSTATION PROJECT S EJO # GS0021

Transcription

1 TRANSMISSION AND SUBSTATION PROJECT S OPERATING COMPANY: EGSI-TX CUSTOMER: COTTONWOOD ENERGY COMPANY, LP EJO # GS0021 FACILITY STUDY OPTIONAL SYSTEM UPGRADES FOR 1240 MW, IPP PROJECT NEAR HARTBURG, TX WITH INTERCONNECTION AT HARTBURG 500KV SUBSTATION CYPRESS 500KV SUBSTATION PROJECT IDENTIFICATION NUMBER 140 REVISION: c c 1/24/02 Issued to Entergy Management Team for Review PEI BO b 1/09/02 Issued to Entergy Jurisdictional Team for Review PEI BO a1 12/26/01 Issued to Entergy IPP Core Team for Review PEI BO a 12/21/01 Issued to Entergy IPP Core Team for Review PEI BO Rev Issue Date Description of Revision Design Engineer Project Manager January 2002

2 Table of Contents Section Page 1. FACILITY STUDY SUMMARY SAFETY STUDY DETAILS FOR SYSTEM UPGRADES (OPTIONAL WORK)...3 A. SUBSTATIONS 3 1. HARTBURG 500/230kv SUBSTATION 3 a. ELECTRICAL WORK...3 b. SITE WORK...7 c. STRUCTURAL WORK...8 d. FOUNDATION WORK...9 e. RELAYING WORK Cypress 500/230/138kv SUBSTATION 13 a. ELECTRICAL WORK...13 b. SITE WORK...17 c. STRUCTURAL WORK...17 d. FOUNDATION WORK...19 e. RELAYING WORK...21 B. TRANSMISSION LINES COST ESTIMATE SUMMARY SCHEDULE MILESTONES OUTAGE REQUIREMENTS ATTACHMENTS...31 HARTBURG 500/230/13.8KV SUBSTATION...31 CYPRESS 500/230/138KV SUBSTATION...31 January 2002 i

3 1. FACILITY STUDY SUMMARY MANDATORY The mandatory work required was defined in a previous study dated March OPTIONAL This section identifies equipment that must be upgraded in order to allow increased power flow over Entergy equipment and facilities. HARTBURG 500/230KV SUBTATION This portion of the Facility Study identifies all of the components necessary to install a new 800MVA transformer bank and de-energize the existing 600MVA transformer bank. The transformer bank replacement is necessary in order to provide increased power flow capability from the Hartburg 500kV yard to the 230kV portion of the yard. In the event of a 500kV line failure between Hartburg and Cypress, an estimated 800MW of power will need to flow into the 230kV system through the transformers at Hartburg. The optional system upgrades at Hartburg, is estimated to be $16,730, This estimate includes overheads and tax gross ups, but not AFUDC. The estimate consists of the following work: Installation of one new 500/230/13.8kV 800MVA autotransformer bank. The bank will comprise four single-phase 160/222/267MVA autotransformers arranged to allow the fourth spare transformer to provide emergency backup in the event of the failure of any one of the three other phase positions by changing the physical connections of the transformers on the high, low and tertiary buses. These transformers will require an oil containment system because the substation site sits next to a designated wetland area. Installation of one new 500kV gas circuit breaker with associated disconnect switches in an empty position of the southeast ring bus. Installation of one new 230kV gas circuit breaker, with associated disconnect switches in the new bay. Installation of a new 230kV South Bus to connect the new transformer bank to the existing Helbig line. The establishment of a new bus and the connection of the Helbig line to the new bus will minimize the outage time required on the Helbig line to install, test and energize all new equipment associated with the installation of the new transformer bank. January

4 The existing 230kV breaker, switches and the existing North Bus will be disconnected and removed. 500kV Breaker will be removed. The Bus No. 1 differential schemes and the breaker failure schemes for several breakers will be modified accordingly. The existing 13.8kV reactors and Alternate Station Service transformer will be connected to the tertiary of the new bank using rigid bus. CYPRESS 500/230/138KV SUBSTATION: The Cypress Substation will be expanded to a 3-position ring bus at 500kV, a 4-position ring bus at 230kV and to a full breaker-and-a-half scheme at 138kV. A 750MVA 500/230kV autotransformer and a 300MVA 230/138kV autotransformer will be added to the station. These two transformer banks along with the existing transformer banks will increase the transfer capability of the station to 750MVA between the 500kV and the 230kV yard, and 600MVA between the 230kV and the 138kV yard. The optional system upgrades at Cypress, is estimated to be $29,836, This estimate includes overheads and tax gross ups, but not ADFUC. The estimate consists of the following work: The installation of three 500kV breakers and associated switches and bus work to create a 3-position ring bus... The installation of three 1-phase 500/230/13.8kV, 150/200/250MVA transformers. The installation of four 230kV breakers and associated switches and bus work to create a 4-position ring bus. The installation of one 3-phase 180/240/300MVA 230/138kV autotransformer bank with LTC. The installation of four 138kV breakers and their associated switches and bus work to create a breaker-and-a-half yard. This study only examined electrical facilities within the Entergy System. Cottonwood Entergy Company LP is responsible for notifying neighboring utilities, for the coordination and accommodation of issues beyond the Entergy System. No Environmental Assessment or Impact Study was undertaken for this Facility Study. If any significant environmental concern is identified during detailed design, this could impact both costs and project duration. January

5 All relevant Entergy standards shall be followed in the implementation of the work outlined in this document. In the case of conflicting information, Entergy Standards and Specifications shall take precedence. * Costs are calculated in 2002 dollars: These estimates are based upon calculations that incorporate current costs and availability for labor, materials, equipment, etc. Any changes in these economic parameters during design and/or construction of these facilities could impact this estimated cost. All quantities listed below are approximate and could change during detail design. 2. SAFETY Safety is a priority with Entergy. Safety will be designed into the substations and lines. The designs will be done with the utmost safety for personnel in mind for the construction, operation and maintenance of the equipment. Modifications required for this interconnection will require personnel to work in energized substations. 3. STUDY DETAILS FOR SYSTEM UPGRADES (OPTIONAL WORK) A. SUBSTATIONS The work for the optional system upgrades of this study will be at the Hartburg and Cypress Substations. 1. HARTBURG 500/230KV SUBSTATION a. ELECTRICAL WORK Reference drawings GJ0021EA1IPPP, GJ0021EA2IPPP, and GJ0021FS1IPPP, GJ0021FS2IPPP, G1167SO5IPPP and G1167SO6IPPP for the work detailed in this section Entergy equipment required for the optional system upgrades will be: ELECTRICAL EQUIPMENT 500kV 1-phase, 500/230/13.8kV, 160/222/267MVA Autotransformer No. 2 3-phase, 500kV, 3000A 63kA gas circuit breaker with two A MR CT s per bushing for relaying, and one 1500/3000-5A DR CT per bushing for metering QUANTITY LEAD TIME* 4 ea 52wks 1 ea 48 wks January

6 ELECTRICAL EQUIPMENT QUANTITY LEAD TIME* 3-phase, 500kV, 3000A motor operated vertical break disconnect 2 ea 24 wks switch without grounding switch 1-phase, 500kV surge arresters 3 ea 52 wks ** 500kV station post insulators 50 ea 10 wks 500kV substation bus and conductor fittings 1 lot 11 wks 5-inch, Sch 40 aluminum bus 710 ft 21 wks 230kV 3-phase, 230kV, 3000A 63kA gas circuit breaker with two A MR 1 ea 24wks CT s per bushing 3-phase, 230kV, 3000A vertical break disconnect switch without grounding 1 ea 24wks switch 3-phase, 230kV, 3000A vertical break disconnect switch with grounding 1 ea 24wks switch 1-phase, 230kV surge arresters 3 ea 52 wks ** 230kV station post insulators 92 ea 10 wks 230kV polymer suspension insulators 12 ea 16 wks 230kV substation bus and conductor fittings 1 lot 11 wks 5-inch Sch 40 aluminum bus 1500 ft 21 wks 1272 MCM ACSR 45/7 conductor strain bus (bundled) 4500 ft 24 wks 15kV 3-phase 15kV, 2000A, 40kA, Outdoor, Vacuum Circuit Breaker with one A MR CT per 3 ea 24 wks bushing 3-phase 15kV, 5400A, Double-side break, gang operated switch 1 ea 24 wks 1-phase, 15kV surge arresters 6 ea 52 wks ** 6-inch Sch 40 aluminum bus 1720 ft 21 wks 15kV station post insulators wks 15kV substation bus and conductor fittings 1 lot 11 wks * Lead time as of January 7, ** Arresters are purchased with and will be delivered with the transformers. Normal lead-time is 16 weeks. January

7 500kV Yard The Southeast node of the South 500kV ring will be used to connect the new transformer bank. Breaker H, and two breaker isolation disconnect switches will need to be installed to complete the node. Once Autotransformer No. 2 is energized, a 500kV breaker can be removed from the 500kV yard. 500/230kV Transformer No. 2 The four new single-phase 500/230/13.8kV autotransformers will be installed south of the 500kV ring bus. These transformers will be arranged such that the spare fourth transformer can be energized in the event of a failure of any one of the other three active transformers via the rearrangement of the high, low and tertiary bus connections. The 500kV bus to the transformer will require a transfer bus to allow any active phase to be reattached to the spare fourth transformer in the event one of the three active transformers fails. Drawing GJ0021EA2IPPP shows the fourth phase as a low bus underneath and adjacent to the 500kV ring bus. The transfer bus can be attached to any of the three active phases by the use of a piece of straight vertical pipe between the phase to be transferred and the transfer bus using bolted fittings. The 230kV and 13.8kV buses run parallel to the transformer bank. As a result, a fourth bus, acting as a transfer bus, will not be required. The spare fourth transformer can be tied to the active phase position, by removing the X1, Y1 and Y2 bus pipe from the failed transformer position and then moving it over to, and reinstalling it on the X1, Y1 and Y2 positions of the spare transformer. The firewalls between the four transformers will be concrete block matching the firewall design used for the existing transformers at Hartburg. The 500kV transformer arresters will be positioned in front of the firewalls on self-supporting steel. Transformer units will have an oil containment system installed. The existing cable trench from the 500kV yard will be extended over to the new transformer bank. The trench is located between the 13.8kV bus and the 230kV bus rather than directly adjacent to the transformer bank. This is to allow ease of access to other equipment in and around the transformers and the oil containment pit, and to isolate the cables contained in the trench from damage due to a fire or an oil spill. January

8 A marshalling cabinet will be installed next to the transformer bank. This cabinet will provide a central connection point for all transformer CT s. When the fourth transformer is moved into a phase position, all CT cables will be reconnected at this cabinet. 230kV Yard A new 230kV South Bus will be established to connect the new transformer bank to the Helbig line. A 1272MCM ACSR, 2 conductor per phase, strain bus will be used to provide the ampere capacity required between the new transformer bank and the new South Bus. Breaker AA, isolation switches and a new line switch will be installed to complete the South Bus arrangement. Once the South Bus is installed and is serving the Helbig line from the new transformer bank, the existing transformer bank, the existing 230kV North Bus and all existing breakers and switches will be removed from service. 13.8kV Yard The existing stepped reactors are rated 11.6MVA at 7960 volts per step per phase. With all three steps in-service, the total current draw by the reactors will be approximately 4300 amperes per phase. The most economical and efficient means to attach the tertiary of the new transformers to the existing reactors is via a rigid bus. Therefore the design calls for the tertiary bus from the new transformers to the existing step reactor banks and the station service transformer to be 6-inch rigid bus. To provide height for yard access underneath the bus between the reactor banks and the new transformers and across the existing road, the estimate is based on the use of 230kV standard steel structures. A 15kV group-operated switch has been added next to Transformer Bank No. 2 to provide isolation of the transformers from the tertiary bus during transformer maintenance. The 3-phase short-circuit duty has increased to approximately 28kA on the existing tertiary bus. As a result, the three existing 15kV breakers protecting the reactor banks will have to be replaced with 40kA units. Station The shielding over the existing 500kV yard will be extended to cover the new transformer bank. The static wire over the new 230kV strain bus will provide protection for the 13.8kV tertiary bus. The addition of two masts and a static wire over the South January

9 bus will protect the new 230kV South Bus. Shielding will be verified during detail design. New AC and DC distribution panels will be installed next to Breaker AA. Assumptions b. SITE WORK The development of this physical arrangement is based on keeping the outage time of the Helbig Line to a minimum. By adding Autotransformer No. 2 to a new bay, creating a new South Bus and a new 230kV breaker bay, all relay schemes for protection of the new transformer can be completed and tested without an outage to Autotransformer No.1 and the Helbig line. The 230kV breaker is rated 63kA to accommodate the future expansion of the 230kV yard by the addition of other transmission lines or the paralleling of a second transformer bank. The rating of the existing reactors is unknown. If the units require replacement, the replacement will impact the layout, installation and design of the 230/13.8kV yard. The following site work will be performed in the 230kV area: surveying, grading, excavation, fill and compaction. Assumptions Wetlands permit for the south end of the yard will not be required. An oil collection system will be required for the new transformers. Site work estimates are based on the upgrade of an area containing approximately 216,000 sq. ft. Soil stabilization is based on an assumed depth of 18-inches. The fill and compact requirement is based on an assumed depth of 24-inches. Final limestone surfacing requirement is assumed to be 6-inches over the entire surface. January

10 c. STRUCTURAL WORK The following steel structures will be installed to support the new electrical equipment and bus work: STRUCTURES 500kV 1-phase, 500kV low bus support (lattice-1 per support) 1-phase, 500kV high bus support (lattice-1 per support) QUANTITY LEAD TIME* 14 ea 20 wks 18 ea 20 wks Shield wire mast 5 ea 20 wks 1-phase, 500kV CVT support (lattice- 1 per support) 1 ea 20 wks 1-phase high surge arrester support 3 ea 20 wks 230kV 3-phase, 230kV low disconnect switch support (tube steel-1 per support) 3-phase, 230kV low disconnect switch support with adaptor for future switch (tube steel-1 per support) 3-phase, 230kV dead-end A-frame structure (tube steel-1 per support) 1-phase, 230kV dead-end pole structure (polygon steel-1 per support) 1-phase, 230kV low bus support (lattice-1 per support) 3-phase, 230kV high bus support (lattice-1 per support) 1-phase, 230kV high bus support (lattice-1 per support) 1-phase, 230kV CVT support (lattice- 1 per support) 15kV 3-phase, 15kV high bus support, (Note: 230kV bus supports will be used for this application) (lattice-1 per support) 3-phase, 15kV high bus support (lattice-1 per support) 3-phase, 15kV high disconnect switch support (tube steel-1 per support) 2 ea 26 wks 2 ea 26 wks 2 ea 26 wks 3 ea 26 wks 12 ea 26 wks 12 ea 26 wks 14 ea 26 wks 3 ea 26 wks 8 ea 20 wks 15 ea 20 wks 1 ea 20 wks January

11 STRUCTURES QUANTITY LEAD TIME* 3-phase high PT stand 1 20 wks * Lead time as of January 7, d. FOUNDATION WORK The following foundations will be installed to support the new electrical equipment and bus work: FOUNDATIONS 500kV 1-phase, 500/230/13.8kV autotransformer bank foundation (1 spread footing per transformer) 3-phase, 500kV gas circuit breaker foundation (spread footing - 1 per phase) 1-phase, 500kV low bus support foundation (drilled pier 1 per support) 1-phase, 500kV high bus support foundation (drilled pier 1 per support) Oil collection system Fire wall between 1-phase transformer tanks Shield wire mast foundation (drilled pier 1 per support) 1-phase, 500kV CVT support foundation (drilled pier 1 per support) 1-phase 500kV surge arrester support 230kV 3-phase, 230kV gas circuit breaker foundation (spread footing - 1 per breaker) 3-phase, 230kV low disconnect switch support foundation (drilled pier-2 per support) 3-phase, 230kV low disconnect switch support foundation with adaptor for future switches (drilled pier-2 per support) 3-phase, 230kV dead end A-frame structure foundation (drilled pier 4 per structure) 1-phase, 230kV self-supporting dead end pole structure foundation (drilled pier 1 per support) 1-phase, 230kV low bus support foundation (drilled pier-1 per support) 3-phase, 230kV high bus support foundation (drilled pier-2 per support) 1-phase, 230kV high bus support foundation (drilled pier-1 per support) QUANTITY 4 ea 3 ea 14 ea 18 ea 1 lot 3 ea 5 ea 1 ea 3 ea 1 ea 2 ea 2 ea 2 ea 3 ea 12 ea 12 ea 14 ea January

12 FOUNDATIONS 1-phase, 230kV CVT support foundation (drilled pier - 1 per support) 15kV 3-phase 15kV high switch stand (drilled pier 2 per support) 3-phase, 15kV high bus support foundation (drilled pier-2 per support) 3-phase, 230kV high bus support foundation (Note: 230kV bus supports will be used for this application) (drilled pier-2 per support) 3-phase PT stand (drilled pier 1 per support) QUANTITY 3 ea 1 ea 15 ea 8 ea 1 ea Assumptions Foundation design is based on the Southwestern Laboratories Soil Boring Report for Hartburg Substation dated March 23, 2001 and its amendments. Boring B-12 was taken in the immediate area of Autotransformer No. 2 and will provide adequate information for the design of the transformer foundations. Foundation size and depth of drilled piers for the 500kV yard to provide adequate lateral resistance and bearing capacity are assumed to be in the range of 12 to 15 feet. Foundation size and depth of drilled piers to provide adequate lateral resistance and bearing capacity for the 230kV yard are assumed to be in the range of 10 feet for the low profile structures and up to 20 feet for the deadend structures. e. RELAYING WORK (See drawings GJ0021OP1IPPP and GJ0021OP2IPPP) The following equipment will be installed to provide relay protection and breaker control for the optional upgrades: RELAYING EQUIPMENT 500kV Breaker control panel (SEL-351) new 500kV breaker QUANTITY LEAD TIME* 1 ea 18 wks January

13 RELAYING EQUIPMENT Line relay panel 500kV L-547 to Cypress Transformer differential panel, 500/230/13.8kV Autotransformer No kV capacitive voltage transformer (CVT), for relaying 230kV Breaker control panel new 230kV breaker 230kV capacitive voltage transformer (CVT), for relaying 13.8kV 13.8kV potential transformer autotransformer #2 tertiary bus QUANTITY LEAD TIME* 2 ea 16 wks 2 ea 16 wks 1 ea 16 wks 1 ea 18 wks 3 ea 16 wks 3 ea 14 wks Station Control cable (inside control building) 1 lot 14 wks Shielded control cable (outside control building) 1 lot 14 wks Outdoor Junction boxes (Line relaying CVT) 2 ea 8 wks Outdoor AC Panel 1 ea 14 wks Outdoor DC Panel 1 ea 14 wks * Lead times as of January 7, kV Yard Two new line relaying panels will be necessary for the 500kV L- 547 Cypress line to accommodate the new ring bus arrangement at Cypress. These panels will be located in the new control building, and will contain the control for line MOS The existing line relaying panels will be removed. The 500kV Bus No. 1 differential scheme as well as the breaker failure schemes for several 500kV breakers will be modified as the result of adding breaker H and removing breaker A new 500kV breaker control panel will be installed in the new control building for breaker H. One new relaying CVT will be added on the 500kV node of the new 500/230/13.8kV autotransformer. January

14 The existing transformer protection panels will be removed following the addition of the new 500/230/13.8kV transformer. The control panel for GCB will remain because it contains the control switches for MOD and MOD kV Yard Three new relaying CVT s will be added on the 230kV node of the new 500/230/13.8kV autotransformer. The existing single phase CVT on the Helbig Line will be reused. A new 230kV breaker control panel will be installed in the old control building for breaker AA. Relaying for the 230kV Helbig L-195 line relaying will be transferred to new breaker AA from existing breaker The control panel for breaker will be removed. 13.8kV Yard Three new 13.8kV PT s will be installed on the tertiary bus of 500/230/13.8kV Autotransformer #2 for over and undervoltage protection. The overcurrent relaying for the existing 13.8kV breakers is located in the breaker cabinet. Since these breakers are to be replaced, new overcurrent relaying will be required with the new 13.8kV breakers. Three new 13.8kV stand alone CT's will be installed on the tertiary bus of Autotransformer #2 to provide current values for the new transformer differential protection. Autotransformers Two transformer differential protection panels will be required to provide dual primary differential protection for the new 500/230/13.8kV transformer. These panels are also to include 500kV and 230kV backup overcurrent relaying, and 13.8kV tertiary over and undervoltage relaying. The new transformer protection panels will be located in the old control building. Station A new outdoor AC panel and outdoor DC panel will be required for the new 230kV yard equipment. January

15 Assumptions The RTU being installed for the mandatory work will be adequate for the optional work. Existing line relaying for 230kV L-195 to Helbig is adequate for the new arrangement. Entergy or its designated contractor/consultant will provide the engineering for relay coordination and determination of the protective relay settings. Entergy or its designated contractor/consultant will set the applicable relays and perform relay calibration, testing and checkout for all Entergy relays. 2. CYPRESS 500/230/138KV SUBSTATION a. ELECTRICAL WORK Please reference the following drawings for the work detailed in this section GJ IPPP, GJ0021FS3IPPP, GJ0021PP1IPPP, and G1210SO6IPPP. ELECTRICAL EQUIPMENT 500kV 1-phase, 500/230/13.8kv, 150/200/250MVA Autotransformer No. 3 3-phase, 500kV, 3000A 63kA gas circuit breaker with three A MR CT s per bushing for relaying. 3-phase, 500kV, 3000A motor operated vertical break disconnect switch without grounding switch QUANTITY LEAD TIME* 3 ea 52wks 3 ea 58wks 3 ea 32 1-phase, 500kV, arresters 3 ea 52 wks ** 500kV station post insulators 162 ea 10 wks 3000A 5-inch aluminum bus, sch ft 21 wks 500kV substation bus and conductor fittings 1 lot 11 wks 230kV 3-phase, 230/138/13.8kV, 300MVA Autotransformer No. 4 with LTC 3-phase, 230kV, 3000A, 63kA gas circuit breaker with two A MR CT s per bushing 1 ea 52 wks 4 ea 24 wks January

16 ELECTRICAL EQUIPMENT 3-phase, 230kV, 3000A vertical break disconnect switch without grounding switch 3-phase, 230kV, 3000A motoroperated, vertical break disconnect switch with grounding switch QUANTITY LEAD TIME* 8 ea 24 wks 3 ea 24 wks 1-phase 230kV surge arresters 6 ea 52 wks ** 230kV suspension insulators (polymer) 6 ea 12 wks 230kV station post insulators 428 ea 10 wks 3000A 5 aluminum bus, Sch ft 21 wks Bus and conductor fittings 1 lot 11 wks 954 MCM ACSR 45/7 conductor strand strain bus 500 ft 24 wks 138kV 3-phase, 138kV, 3000A, 63kA gas circuit breaker with two A MR 4 ea 24 wks CT s per bushing 3-phase, 230kV, 3000A vertical break disconnect switch without grounding 8 ea 24 wks switch 230kV station post insulators 81 ea 10 wks 230kV polymer suspension insulators 12 ea 12 wks 3000A, 5-inch aluminum bus, Sch ft 21 wks bus and conductor fittings 1 lot 11 wks 1272MCM ACSR 45/7 strand conductor strain bus 2000 ft 24 wks 1-phase 138kV surge arresters 3 ea 52 wks ** 15kV 15kV insulators 18 ea 18 wks 1-phase surge arresters 6 ea 52 wks ** 6-inch, Sch 40 Aluminum bus 330 ft 21 wks Bus and conductor fittings 1 lot 11 wks Battery building (240 sq ft) 1 ea 12 wks * Lead times as of January 7, 2002 ** Arresters are purchased with and will be delivered with the transformers. Normal lead-time is 16 weeks. January

17 500kV yard The existing 500kV radial feed from the Hartburg Substation will be expanded into a ring bus to provide the source node for the new 500/230kV Autotransformer No. 3. Breakers A1, A2 and A3 will be added along with the switches and bus work necessary to create the ring. The new 500/230kV Transformer Bank No. 3 will be located adjacent to the existing 500/138kV Autotransformer Bank No 1. A concrete block wall will be placed on each side of the center unit to provide a fire barrier between each unit in the event one of the units should fail and catch on fire. The tertiary on each unit has been brought out of the tank. A 3-phase, 6-inch rigid bus will be run along the top of the fire walls to connect the tertiary windings into a delta. There are no plans to use the tertiary windings to serve a load at this time. 230kV Yard The existing 230kV yard will be expanded into a 4-position ring bus using a layout that can ultimately be expanded into a breakerand-a-half scheme. Breakers B1, B2, B3, and B4 with their associated isolation switches will be added to the ring to provide separate bays for the existing Amelia Line, existing Autotransformer No. 2, and new Autotransformer No. 3 and No. 4. A new 230/138kV, 300MVA transformer bank will be added to provide increased capacity between the 230kV and the 138kV yards. A 230kV motor-operated switch will be provided on the primary side of the transformer so the 230kV ring bus can be isolated from the transformer and the ring closed in the event of a transformer failure. The new transformer bank is being purchased with an LTC and all equipment necessary to put in-service an automatic paralleling scheme between Autotransformer No. 2 and No. 4. The tertiary has been brought out of the tank. Since there are no plans to use the tertiary to serve a load the tertiary bushings will be connected to 15kV arresters only. Low profile rigid bus will be used to tie Autotransformer No. 3 to a new 230 bay between breakers B1 and B2. The existing 230kV Amelia line will have a motor-operated line switch added so the line can be isolated from the ring and the ring closed in the event of a line failure. 138kV Yard The 138kV yard will be expanded to a breaker-and-a-half scheme by the addition of Breakers C1, C2, C3 and C4 and their associated January

18 isolation switches. After completion of these upgrades, each existing line, Autotransformer No. 2 and Autotransformer No. 4 will have their own line bay. The breaker-and-a-half scheme is necessary to provide assurances that the failure of any single breaker in the 138kV yard will not cause the simultaneous loss of two of the three transformers connected to the 138kV yard. A strain bus will be used to connect Autotransformer No. 4 to the line bay between 138kV breakers C2 and C3. Station A small auxiliary battery building will be added next to the existing control building. The battery room in the present building is too small to add a second 125Vdc battery set. The battery building will be a self-supporting, pre-engineered building, sized just to contain the new battery set. The chargers, and DC panels associated with the new battery set will be installed in the existing control building. The existing station shielding uses a combination of 170-foot masts and shield wires. The number and location of new masts shown is based on the use of this system. Several masts are required to cover the area being developed by the expansion of the three yards. Shielding will be verified during detail design. Assumptions Oil containment will not be required at this station Two of the existing switch racks have bent switch platforms. We are assuming that these platforms do not need to be replaced, but can be straightened by adding additional bracing. The 138kV yard is built using 230kV switches, and highstrength insulators. Only the breakers are rated 138kV. All new equipment is specified to match the existing design. A 138kV, 63ka GCB requires a larger bay area than a 40kA GCB because of the capacitor attached to acquire the 63kA rating. It is assumed that the existing bay space in the 138kV yard is adequate for the new breakers and that existing switch stands will not have to be moved to provide adequate space. January

19 SITE WORK The following site work will be performed in the 500kV and 230kV area: surveying, grading, excavation, fill, compaction and the addition of a second gate at the entry road. Assumptions Wetlands permit will not be required for this site. The storage yard fence will have to be relocated to accommodate the extension of the station road to the south. The gate and access to the yard may have to be moved as well. All roadways associated with the delivery of new transformer units will require upgrading. Site work estimates are based on the upgrade of an area containing approximately 378,000 sq. ft. Soil stabilization is based on an assumed depth of 12-inches. The fill and compact requirement is based on an assumed depth of 18-inches. Final limestone surfacing requirement is assumed to be 6-inches over the entire surface. c. STRUCTURAL WORK The following structures will be installed to support the new electrical equipment, bus work, and transmission line termination: STRUCTURES 500kV 3-phase, 500kV high disconnect switch support (lattice-6 per switch) 3-phase, 500kV low disconnect switch support with adaptor for future switches (lattice-6 per switch) 3-phase, 500kV high disconnect switch support with adaptor for future switches (lattice-6 per switch) 1-phase, 500kV low bus support (lattice-1 per support) 1-phase, 500kV high bus support (lattice-1 per support) 1-phase, 500kV arrester support (lattice-1 per support) QUANTITY LEAD TIME* 3 ea 20 wks 3 ea 20 wks 3 ea 20 wks 48 ea 20 wks 51 ea 20 wks 3 ea 20 wks January

20 STRUCTURES Shield wire mast (lattice-1 per structure) 1-phase, 500kV CVT support (lattice- 1 per support) 230kV 3-phase, 230kV low disconnect switch support (tube steel-1 per support) 3-phase, 230kV low disconnect switch support with adaptor for future switch (tube steel-1 per support) 3-phase, 230kV dead-end A-frame structure (tube steel-1 per support) 1-phase, 230kV low bus support structure (tube steel-1 per support) 1-phase, 230kV high bus support structure (tube steel-1 per support) 3-phase, 230kV high bus support structure (tube steel-1 per support) 1-phase, 230kV CVT support structure (tube steel-1 per support) 138kV 3-phase, 230kV low disconnect switch support (tube steel-1 per support) 3-phase, 230kV dead-end A-frame structure (tube steel-1 per support) 1-phase, 230kV low bus support structure (tube steel-1 per support) 1-phase, 230kV CVT support structure (tube steel-1 per support) QUANTITY LEAD TIME* 11 ea 20 wks 3 ea 20 wks 10 ea 26 wks 4 ea 26 wks 2 ea 26 wks 40 ea 26 wks 10 ea 26 wks 58 ea 26 wks 4 ea 26 wks 4 ea 26 wks 3 ea 26 wks 9 ea 26 wks 3 ea 26 wks 13.8kV 3-phase high bus support 4 26 wks 3-phase high PT support 1 26 wks * Lead time as of January 7, Assumptions A motor-operated line switch must be added to the Amelia line. We assume that the existing deadend has been designed to allow for the addition of this switch. January

21 Switch structures, with solid bus across them, will be used in those locations where the switches are shown as future. Two existing 138kV switch support structures can be reused if vertical bracing is provided for the horizontal beams. The 138kV yard is built using 230kV steel and deadends. Only the breakers are rated 138kV. All new steel and deadends are specified to match the existing design. The estimate calls for three 230kV deadend structures for the strain bus from the 138kV yard to the new 300MVA Transformer No. 4. If the analysis of the steel will allow the strain bus to span the 138kV East Bus and the 230kV rigid bus between Autotransformer No. 3 and the 230kV yard, then one deadend can be removed. d. FOUNDATION WORK The following foundations will be installed to support the new electrical equipment and bus work: FOUNDATIONS 500kV 1-phase, 500/230/13.8kV autotransformer bank foundation (1 spread footing per transformer) 3-phase, 500kV gas circuit breaker foundation (spread footing - 1 per phase) 3-phase, 500kV high disconnect switch support foundation (drilled pier 6 per support) 3-phase, 500kV low disconnect switch support foundation with adaptor for future switches (drilled pier 6 per support) 3-phase, 500kV high disconnect switch support foundation with adaptor for future switches (drilled pier 6 per support) 1-phase, 500kV low bus support foundation (drilled pier 1 per support) 1-phase, 500kV high bus support foundation (drilled pier 1 per support) 1-phase, 500kV arrester support foundation (drilled pier-1 per support) Shield wire mast foundation (drilled pier 1 per support) 1-phase, 500kV CVT support foundation (drilled pier 1 per support) QUANTITY 3 ea 9 ea 3 ea 3 ea 3 ea 48 ea 51 ea 3 ea 11 ea 3 ea January

22 FOUNDATIONS 230kV 3-phase, 230/138/13.8kV autotransformer foundation 3-phase, 230kV gas circuit breaker foundation (spread footing - 1 per breaker) 3-phase, 230kV low disconnect switch support foundation (drilled pier-2 per support) 3-phase, 230kV low disconnect switch support foundation with adaptor for future switches (drilled pier-2 per support) 3-phase, 230kV dead end A-frame structure foundation (drilled pier 4 per structure) 1-phase, 230kV low bus support foundation (drilled pier-2 per support) 1-phase, 230kV high bus support foundation (drilled pier-1 per support) 3-phase, 230kV high bus support foundation (drilled pier-2 per support) 1-phase, 230kV CVT support foundation (drilled pier - 1 per support) 138kV 3-phase, 138kV gas circuit breaker foundation (spread footing - 1 per breaker) 3-phase, 230kV low disconnect switch support foundation (drilled pier-2 per support) 3-phase, 230kV dead end A-frame structure foundation (drilled pier 4 per structure) 1-phase, 230kV low bus support foundation (drilled pier-1 per support) 1-phase, 230kV CVT support foundation (drilled pier - 1 per support) 15kV 3-phase high bus support (drilled pier 1 per support) 3-phase high PT support (drilled pier 1 per support) Battery Building (spread footing) QUANTITY 1 ea 4 ea 10 ea 4 ea 2 ea 40 ea 10 ea 58 ea 4 ea 4 ea 4 ea 3 ea 9 ea 3 ea 4 ea 1 ea 1 ea January

23 Assumptions The firewalls between the new transformers will be block walls. The block wall structure estimate is based on the wall installed at Hartburg Substation shown on Drawing No. G The expansion of the 230kV yard will include switch structures in those areas where the breaker isolation switches are future. Foundations for deadend structures will not be added in those locations where the line bays are future. Instrument and arrester foundations will not be added in those areas of the 230kV and 138kV yards where the line deadends are indicated as future. Soil report indicates a soft layer near the surface of the yard. Soil analysis during design may require the actual foundations to be deeper to compensate for this condition. Foundation depth for drilled piers for the 500kV yard are assumed to be in the range of 12 to15 feet to provide adequate lateral resistance and bearing capacity. Foundation depth of drilled piers for the 138kV and 230kV yard are assumed to be in the range of 10 feet for low profile structures and up to 20 feet for the deadends to provide adequate lateral resistance and bearing capacity. e. RELAYING WORK (See drawings GJ0021OP3IPPP, GJ0021OP4IPPP, GJ0021OP5IPPP, and GJ0021SK2IPPP) The following equipment will be installed to provide relay protection and breaker control for the optional upgrades: PROTECTION EQUIPMENT 500kV Transformer differential panel, 500/138kV Autotransformer No. 1 Transformer differential panel, 500/230/13.8kV Autotransformer No. 3 QUANTITY LEAD TIME* 2 ea 16 wks 2 ea 16 wks January

24 PROTECTION EQUIPMENT Breaker control panels (SEL-351) new 500kV breakers Line relay panel 500kV L-547 to Hartburg 500kV capacitive voltage transformer (CVT), for relaying 230kV Transformer differential panel, 230/138/13.8kV Autotransformer No. 2 Transformer differential panel, 230/138/13.8kV Autotransformer No. 4 Breaker control panel (SEL-351) new 230kV breakers 230kV capacitive voltage transformer (CVT), for relaying 138kV Bus differential panel for East and West 138kV Busses Breaker control panel (SEL-351) new 138kV breakers 138kV capacitive voltage transformer (CVT), for relaying 13.8kV 13.8kV potential transformer autotransformer #3 tertiary bus QUANTITY LEAD TIME* 3 ea 18 wks 2 ea 16 wks 3 ea 14 wks 2 ea 16 wks 2 ea 16 wks 4 ea 18 wks 4 ea 14 wks 2 ea 16 wks 4 ea 18 wks 3 ea 14 wks 3 ea 14 wks Station Control cable (inside control building) 1 lot 14 wks Shielded control cable (outside control building) 1 lot 14 wks Stand alone AC panel 1 ea 14 wks Stand alone DC panel 2 ea 14 wks Outdoor DC panel 3 ea 14 wks Outdoor AC panel 3 ea 14 wks Outdoor 480V-240/120V AC 3 phase station service transformer 4 ea 16 wks 125VDC, 440AH Battery Set and Rack 1 ea 16 wks January

25 PROTECTION EQUIPMENT QUANTITY LEAD TIME* 50A battery charger 1 ea 16 wks 200A battery test switch panel 2 ea 16 wks Outdoor Junction boxes (2 Bus relaying CVT, 7-Line relaying CVT) 9 ea 8 wks Indoor Junction boxes (Bus potential distribution box) 2 ea 8 wks GE Harris D20 RTU 1 ea 16 wks Teltone SLSS Line Sharing Switch 1 ea 8 wks SEL-2030 Communications Processor 2 ea 8 wks SEL-Starcomm Modem 2 ea 8 wks GE-Harris Telenetics Modem 1 ea 8 wks * Lead time as of January 7, kV Yard Two relaying CVT s will be installed on the 500kV bus at the high side of autotransformers #1 and #3. One relaying CVT will be installed on the 500kV Hartburg line on the line side of the switch to provide voltage sensing. Two new line relaying panels will be necessary for the 500kV L- 547 Hartburg line to accommodate the new ring bus arrangement. There will be two new stand alone DC panels (one on each battery bank) and one new stand alone AC panel placed in the control building to serve the new 500kV equipment, including transformer #3. To provide voltage support in the yard, we will locate a new 480V-240/120V station service transformer. The 480V input for this transformer will be fed from the existing 480V AC panels. This local transformer will be served from the new panels located in the Control Building. 230kV Yard Three new relaying CVT s will be installed on the 230kV bus, one for the low side of autotransformer #3, and two for the high side of autotransformers #2 and #4. Additionally, one CVT will be added to the 230kV Amelia L-488 on the line side of the line disconnect switch to provide voltage sensing. The existing 230kV L-488 to Amelia relaying will be maintained, and moved to the appropriate new breakers in the 230kV ring bus. There will be one new outdoor DC panel and one new outdoor AC panel placed in the 230kV yard for the new equipment. To provide voltage support in the yard we will locate a new 480V-240/120V January

26 station service transformers. The 480V input for this transformer will be fed from the existing 480V AC panels. This local transformer will be served from the new panels located in the Control Building 138kV Yard With the 138kV additions to make a breaker-and-a-half scheme, there will be two 138kV bus differential protection panels required, one for each bus. Additionally, the existing 138kV breaker controls will be modified to support the new breaker and a half scheme. There will be two new outdoor DC panels and two new outdoor AC panels placed in the 138kV yard for the new equipment. To provide voltage support in the yard we will locate a new 480V- 240/120V station service transformers. The 480V input for this transformer will be fed from the existing 480V AC panels. This local transformer will be served from the new panels located in the Control Building 13.8kV Yard Three new 13.8kV PT s will be installed on the tertiary bus of 500/230/13.8kV Autotransformer #3 for over and undervoltage protection. Autotransformers The new 500/230/13.8kV and 230/138/13.8kV transformers will each be required to have dual primary differential protection. The existing 500/138kV and 230/138kV transformer relaying will need to be replaced with new transformer protection panels to support the new substation configuration. Therefore, the relaying for the two new and the two existing transformers will all be identical, with the exception of the tertiary protection required for 500/230/13.8kV autotransformer #3. Each transformer will have dual primary transformer differential, high side overcurrent, and low side overcurrent protection, and will require two new panels each. The existing 500/138kV autotransformer #1 revenue metering panel will be removed. Station All new 500kV, 230kV, and 138kV breakers will require a breaker control panel to be added, utilizing the SEL-351 relay. The SEL- 351 will provide synchronizing supervision for the new breakers. January

27 The existing 138kV breakers utilize a sync scope and an autosynchronizing relay scheme to supervise closing of each breaker. This equipment will remain, and new breakers will be added to the existing sync scope for manual synchronizing if the new panel is in the same panel lineup. A new GE-Harris D20 RTU will replace the existing RTU. All points on the existing annunciators will be moved, point-to-point, to the new RTU, and the annunciators removed upon completion. The new RTU will be required to communicate with the TOC simultaneously with the existing RTU during construction, and will therefore require an additional data circuit. The new 500kV breakers will have trip coil #1 and trip coil #2 supplied by two independent 125VDC battery sets. The existing 138kV breakers will operate as they are currently connected on the existing battery set. The existing 125VDC battery set will supply the new 138kV breakers. The new 125VDC battery set will supply the new 230kV breakers. All new relaying will have primary and backup relays separated between new and existing 125VDC battery sets. Existing relaying will be supplied as currently connected. The new 125VDC panels will be sized to provide enough pole positions for separation of trip coil #1 and trip coil #2 for the 138kV breakers in the future. All new and existing breakers in the 138kV yard will use the existing battery set. The 230kV yard will be connected to the new battery set. The 500kV yard will use both battery sets. A new Teltone Substation Line Sharing Switch (SLSS), two new communications processors, and associated modems will be added to provide remote access to the new relaying equipment and RTU. Assumptions There is sufficient space in the existing control building for all new protection panels, AC and DC panels, and communications equipment. Existing line relaying for all 138kV lines and 230kV L-488 to Amelia is adequate for the new arrangement. January

28 Entergy or its designated contractor/consultant will provide the engineering for relay coordination and determination of the protective relay settings. Entergy or its designated contractor/consultant will set the applicable relays and perform relay calibration, testing and checkout for all Entergy relays. New synchronizing scope panels are not necessary for new breakers for Entergy operational use. The existing microwave system has sufficient capacity to support the additional channels needed for communication with the TOC. The Entergy System Operations Center (SOC) will not require a separate data circuit to be added for RTU information. The existing 300kVA station service transformer is rated to handle new equipment loads in addition to the existing loads. B. TRANSMISSION LINES There is no optional transmission line work designated in this study. 4. COST ESTIMATE SUMMARY SYSTEM UPGRADES The total cost for the system upgrades that is optional work is listed below: Hartburg 500/230kV Substation $16,730,464 Cypress 500/230/138kV Substation $27,836,668 TOTAL COST Total cost for the OPTIONAL work above is: $44,567,132 The quantities of materials listed in this document are approximate and could change with completion of detail design. The costs include taxes, overheads, but not AFUDC. Note: if progress payments are not completed, AFUDC will be added. 5. SCHEDULE MILESTONES Entergy will make commercially reasonable efforts to complete this project to meet your requested in-service date. The project durations outlined below are based on January

29 the existing executed Interconnection and Operating agreement. We also note that the ability of Entergy to schedule power outages on its substation and transmission systems is very limited year-round and not possible at all during peak summer months (June 1 through to September 30). Further, by regulation, available transmission transfer capacity is committed up to thirteen months in advance and this could limit outage capabilities. Finally, long lead times for critical materials identified in this schedule are based on current lead times offered by our suppliers and are subject to change with the commitment of actual purchase orders. For these and other reasons, Entergy cannot guarantee the completion date of the required or optional system improvements, regardless of when the customer executes an Interconnection and Operating agreement. HARTBURG 500/230KV SUBSTATION The estimated total project duration for the optional work is approximately 12 months. DESCRIPTION Site Work Design Package Foundation Design Package Electrical Design Package Relay Design Package Relay Settings Package Site Preparation Construction Foundation Construction Electrical Construction Relay Construction ACTIVITY DURATIONS 6 wks 9 wks 14 wks 16 wks 10 wks 6 wks 16 wks 18 wks 18 wks CYPRESS 500/230/138KV SUBSTATION The estimated total project duration for the optional work is approximately 19 months. DESCRIPTION Site Work Design Package Foundation Design Package Electrical Design Package Relay Design Package Relay Settings Package ACTIVITY DURATIONS 10 wks 14 wks 24 wks 26 wks 15 wks January

30 DESCRIPTION Site Preparation Construction Foundation Construction Electrical Construction ACTIVITY DURATIONS 8 wks 18 wks 20 wks Relay Construction 26 wks ** The construction will be performed in stages in order to ensure the earliest possible energization date. 6. OUTAGE REQUIREMENTS SYSTEM UPGRADES All outages must be coordinated by the Entergy Construction Manager and approved by Entergy System Operations. The actual sequence and duration of any outage will be determined by Entergy and may or may not follow the outline below. Any additional costs required to install, and later remove, any temporary alternate feeds to facilitate permanent line or station construction outages are not included in this study, unless specifically noted. HARTBURG 500/230KV SUBSTATION Outage Outage Id Description Install Breaker H & Connect Xfmr 2 to 500kV Bus No-load Test Transformer No. 2 Move Helbig line to South Bus. Work Description Open and MO Connect Xfmr 2, diff scheme to H. Connect Xfmr 2 to 500V bus. Leave GCB open Close H & 13630, and energize Xfmr 2. Test transformer A, 13.8kV Sw. XXXX and GCB AA remain open Open13135 and AA. Move Helbig line to south bus. Close AA and leave open. Outage Start Date Duration (Days) January

31 Outage Id 4 Outage Description De-energize Xfmr 1. Remove breaker Work Description Open and MO Remove Xfmr 1 HV/LV jumpers. Add GCB H BF scheme to Remove Xfmr 1 relaying from & Connect Xfmr 2 tertiary bus to step reactors Close 5000A 13.8kV Sw XXXX, GCB and MO Outage Start Date Duration (Days) 7 CYPRESS 500/230/138KV SUBSTATION Outage Outage Id Description 1 Install Xfmr 4 strain bus and breakers C2 & C3 Work Description Open Sw & OCB (de-energize the East Bus). Set Xfmr 4 DE between C2 & C3. Pull strain bus over East Bus. Set bus-side disconnects for 22050, C2 & C3. Set and connect East Bus CVT. Outage Start Date Duration (Days) 5 2 Install C4 and connect to C3 3 Install C1 Leave jumpers off between 138kV bus and Strain Bus Open & (deenergize West Bus). Install C4 and C4 bus-side & line side switches. Install bus between C3 and C4. Install West Bus CVT. Add West Bus Diff scheme to 22070, & C4. Modify BF scheme & to include C4. Open Sw 22081, & C2 (de-energize West Bus). Set GCB C1. Install East Bus Diff scheme. Modify BF for C1, C2, & January

32 Outage Id 4 Outage Description Install Breaker B3 & Line switch for L-488 Energize Xfmr 4 Work Description Open and C1. (deenergize Xfmr 2 and line L- 488). Set B2 bus-side switch, B3 and both B3 isolation switches. Complete BF scheme between B2, B3 & C1. Set Install L-488 line switch. Establish Line L-488 line relays on breaker B3 & B4. Place Auto # 4 in service using line L-488. Install strain bus jumpers. Close B3 and B4. Test Xfmr 4. Close C2 and C3 Outage Start Date Duration (Days) L days Auto #2 10 days Energize Xfmr 2 Install breaker A2 Close 500kV ring. Continue to re-work Auto No. 2 relay scheme. Place Auto No. 2 back in service. Open 2045, and Sw (de-energize Hartburg line L-547 and Xfmr 1). Set breaker A2.. Reconnect line CT s from Xfmr 1 CT s to GCB s A1 & A2. Connect to GCB A3 Hartburg line 2 days 5 Energize Xfmr 3 Close GCB A1 and test new transformer Modify Xfmr 1 protection schemes Complete 500/138kV Auto No. 1 diff and BF schemes between A2, A & Xfmr 1 10 days Close A2, A3, 2045 & January