SAUDI ELECTRIC COMPANY As the Kingdom’s demand for electrical power in the industrial and agricultural sectors of the economy grew, the Government replaced the old fragmented system of electrical power generation (provided by numerous small companies) with SCECOs – Saudi Consolidated Electricity Companies – each providing electricity for a whole region of the Kingdom. The first SCECO (SCECO-East) was created in 1977, with a capital of SR 5 billion. This was followed in 1979 by SCECO-South, with a capital of SR 4 billion, serving more than 1,447 cities and villages and SCECO-Central, with a capital of SR 8 billion, serving more than 600 cities and villages, including Riyadh. Electricity for the southwest of the Kingdom was provided by SCECO-West, established in 1982, with a capital of SR 8 billion. To improve and strengthen the power industry, in 1998, the Council of Ministers issued Resolution Number 169 for the restructuring of the electricity sector, aiming to reform its finances and increase the participation of the private sector in its ownership, 1
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SAUDI ELECTRIC COMPANY
As the Kingdom’s demand for electrical power in the industrial and agricultural sectors of the economy grew, the Government replaced the old fragmented system of electrical power generation (provided by numerous small companies) with SCECOs – Saudi Consolidated Electricity Companies – each providing electricity for a whole region of the Kingdom. The first SCECO (SCECO-East) was created in 1977, with a capital of SR 5 billion. This was followed in 1979 by SCECO-South, with a capital of SR 4 billion, serving more than 1,447 cities and villages and SCECO-Central, with a capital of SR 8 billion, serving more than 600 cities and villages, including Riyadh. Electricity for the southwest of the Kingdom was provided by SCECO-West, established in 1982, with a capital of SR 8 billion.
To improve and strengthen the power industry, in 1998, the Council of Ministers issued Resolution Number 169 for the restructuring of the electricity sector, aiming to reform its finances and increase the participation of the private sector in its ownership, management and energy conservation. The resolution stipulated the following:
Establishment of a joint stock company for electricity to be called the Saudi Electric Company (SEC).
Merging all the local electricity utility companies, as well as the electricity facilities owned by the General Electricity Corporation into the Saudi Electric Company.
Creation of an independent agency during the first year of the company’s establishment to review periodically the costs and tariffs of the electricity service according to defined principles.
Liquidation of the General Electricity Corporation. A ministerial committee would undertake the development and
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execution of the liquidation plan, including the settlement of its liabilities, while preserving the full rights of its staff.
In 2000, the Minister of Commerce issued Resolution Number 2047, announcing the establishment of the Saudi Electric Company.
Statistics on electricity generation between 1970 and 1999
Subject 1970 1989 1999
Power generated (million KwH) 1,825 61,568 114,624
Power sold (million KwH) 1,690 55,201 105,612
Number of subscribers (thousands) 216 2,259 3,372
SYSTEM MODELING AND REQUIREMENTS
A. Generators
Generators are driven by turbines, diesel engines, water wheel, or other types of generators. When a short circuit occurs, the generator continues to produce voltage because the field excitation is maintained and the prime mover drives he generators at normal speed. The generated voltage produces a short circuit current of large magnitude that flows from the generators to the sort circuit.
The magnitude of that current is limited only by the impedance of the generator and the circuit impedance between the generator and the fault location. For a short circuit at the terminals of a generator, the current fed from this generator is limited only by its own impedance
B. Synchronous Motors
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A synchronous motor is constructed much like a generator/ it has a field winding excited by a D.C current and a stator winding fed from an A.C source. During a short circuit, the voltage of the system is reduced to a very low value. Consequently, the motor stops delivering energy to the mechanical load and starts slowing down. However, the inertia of the load and the motors rotor continue driving the synchronous motor
C. Induction Motors
The inertia of the load and the rotors of an induction motor has the same effect on an induction motors as on a synchronous motor. However, there is a major difference, which is the induction motor has no D/C field winding.
The field of the induction motor is produced by induction from the stator winding. The rotors flux remains normal as long as the voltage is applied to the stator from and external source. If the external source is suddenly removed, when a short circuit occurs, the flux in the rotor can not change instantly. Then the stored energy in the rotating parts drives the induction motor and a voltage is produced in the stator windings.
This causes a current to flow to the shorts circuit until the rotors flux decays to zero. Since there is not sustained filed current, the shorts circuit current decays in a few cycles. However, the flux last long enough to produce a current which contributes to the total short circuit current.
D. Capacitors and Transformers
The discharge, outrsuch, current from power capacitors to a system fault of high frequency with a very shorts time constant (RC).
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Thereof, the contribution of power capacitors to system faults can be neglected.
Transformers are not sources producing short circuit current. Although the transformers connection greatly affects the ground faults, transformers are never short circuit sources but merely receive and deliver the short circuit current from one side to the other.
E. Transmission Plan
The transmission network is designed to cater for the basic reliability requirement of single contingent outage of network elements. The high reliability is maintained by using proven equipment and the continual monitoring and remote control of the network from the Power System Control Centre (PSCC).
The design of the transmission equipment and cable are standardized. This has the following advantages:
i) Minimum inventory costs for spare parts. ii) Economics of scales in purchasing. iii) Simplicity in design and operations
F. Planning And Design
In general, the process of the planning and design of transmission lines consists of the following five phases.
Planning: The master guidelines of route constructions are settled based on the long-range power supply plan. The outline is determined for each transmission line planned, which includes voltage, number of lines, starting and ending substations.
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Survey: Information about natural environment, geological features, local communities and regulations in the area of interest etc. is collected in this phase and several alternative routes are compared in terms of environmental impact, technical issues and cost of construction.
Basic Route: Basic route is determined by the position of each tower along the proposed routes and interference of radio wave caused by the transmission line is estimated. All this is done using a medium scale top sheet.
Detailed Route: A photogram metric surveying is performed along the basic route. Based on the results, the detailed position of each tower is determined in the large scale (1:2,000) . And engineering design process follows, which includes the determination of tower type, tower height and supporting devices, and the cost estimation.
Route for Implementation: In this phase, the detailed field surveying is performed along the determined route. The towers, wires and basement of towers are designed.
MODELING OF POWER SYSTEM COMPONENTS
A. Rotating Machines
Every rotating machine is represented by its respective saturated direct-axis subtransient reactance which determines the magnitudes of the fault current in the first few cycles.
B. Transformers
Despite the plenty of transformer connection, the following representation will be limited to the most frequent ones used in the SEC power system
Two-winding transformers: the two winding transformers are modeled in the positive, negative and zero sequence networks
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Three-winding Transformers: three winding transformers are usually used for there bulk transmission level. In SEC, these transformers are connected as Y-grounded / Y-grounded in addition to a Delta tertiary winding. The impedances of the primary (p), secondary (S), and tertiary (t) winding are related to each others.
C. Transmission Lines And Loads
Transmission lines (both overhead lines and underground cables) are modeled by their series sequence impedance. Positive sequence shunt admittance is usually neglected. Static load are also neglected since they do not represents as sources and hence do not contributes to the fault current.
TWO STUDY CAUSES
There are many cases for the process of planning for transmissions lines. Because of that, it is difficult to mention all of them. During the cope period, I have chosen two cases that show the this process fully. The first one is for Al-Senaeyah. The second one is for Aramco. There are many differences between the two areas and because of these differences, these two cases have been chosen. One of the most important differences is that the transmission lines of Al-Senaeyah are underground while the Aramco’s projects use overhead transmission lines. Moreover, it is a well known fact that Aramco demands special requirements for its different part and many sites and locations and facilities. These two cases are discussed in the following pages.
A. Al-Senaeyah
The first case is for establishing underground transmission lines for Al-Senaeyah. This part is divided into three sections in order to
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discuss the process from different angles. The first one is the systems requirement. The second one is the planning process and finally the third one is the objectives and output of the project.
System Requirements
There are many type of requirements that must be available for completing the ground transmutation lines for Al-Senaeyah. In this part, these requirements are presented and discussed.
1. All components and accessories required for the completion and successful operations of the project must be available before starting the project in order to cope with the schedule and budget of the project.
2. The engineering design and specifications of equipment/materials supplied must be in accordance with the scope and purpose of the project and the technical specifications.
3. the engineering and design works must be carried out by an engineering and design firm which has registration to carryout engineering and design works in the Kingdome of Saudi Arabia. The proposed engineering and design firm must also be from Saudi Electricity Company acceptable list of engineering Design firm or must get pre-qualified.
4. The base design shall be finalized at base design review-meeting based on the guideline drawings issued hereof manufacturer’s drawings, calculations and data sheets and detailed design must be finalized based on the base design review and other required information.
5. a Kick-off meeting must be held for covering issues such as project implementations, scope of the work and schedule.
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Planning Process
The base design phase of the project is 10-12 weeks period of primary engineering following the kick-off meeting. The purpose of the base design phase is to completely define the project in enough details in which all requirements are being incorporated. Information developed during the design should be used as a guide throughout the project. The design phase will include:
1. Narrative scope of work which includea. Description of workb. Design basis and datac. Testing and commissioning proceduresd. Maintenance aspectse. Special considerations including design, construction
operation constraints, problems areas and proposed solutions.f. List of items of all equipment/facilities to be installed and
description of all work to be accomplished. This listing is to be broken down by location, job phase and quantities of like items.
2. Detailed project schedule and critical path.3. Major materials purchases requisitions4. Design calculations which include:
a. detailed cable Ampacity calculationsb. Electrical interference study in case the power cable parallels
the communications circuitsc. Calculation of power cables sequence impedance.d. Calculation for cable metallic sheath, fault current withstand
capability and groundinge. Calculation for sheath standing voltage, sheath voltage rise
and the selection of Sheath voltage limitations (SVL)f. Structure calculation for duct banks on road crossings.g. Detailed explanation for adopting the major/minor sections
arrangement of the cross bondingh. Cable pulling tension and sidewall pressure calculations
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5. Soil investigation report for thermal and electrical receptivity measurement along the whole cable route. 6. The drawing from this phase must include:
a. Drawing control sheetb. Abbreviations, Symbol and legendsc. Plot pland. 69kV underground system one line diagrame. Non-metallic fiber optic system one line diagramf. 96kV power and fiber optic cables routing plant and profileg. cable termination arrangement plan sections and detailsh. cable metallic sheath grounding arrangement and detailsi. link box location, connections and detailj. 96kV power and opticak fiber cable routing sections,
elevations and detailsk. foundation details for 69kv cable box and other support
structuresl. details of trenches duct banks and hand holesm.Bonding of trenches duct banks and hand holesn. bonding method and grounding arrangement detailso. Interface diagram with 69kV switchgear at DIE1A, DIE1Bm
DIE1C and 2A substations. 7. Manufacturing’s technical specifications (literature, catalog, drawings, type test report and completed data schedules) of the following equipment:
a. 69kV power cableb. Grounding cablesc. Non-Metallic fiber optic cabled. Non-Metallic fiber optic cable accessoriese. 69kV cable termination/Splice Kitsf. Cable supportsg. Sheath voltage limiterh. Lin boxi. Link Box foundationsj. Link Box Barricade Arrangementk. Cable Warning Tape
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l. Cable titlesm.Wire meshn. Cable warning posto. Duct sealing unitsp. Cable title coverq. PVC conduits and fittingsr. Power cable clampss. Fire proofing material to protect the cable in cable basementt. Material related to fiber optic cables
8. Type test reports for major equipment/materials9. Factory and site test program10. Job safety plan11. Site security plan12. QA/QC plan
Objectives And Output
There are five types of underground transmission lines for the project of Senaeyah. These four lines are as the following:
1. Al-Senaeyah BSP – DIE Sub # 1C
Provide and install approximately 1.8 km 24 cores, single mode, non-metallic underground fiber cable along with the 69kV cable in PVC duct/sub ducts from Al-Senaeyah BSP up to the hand hole HH#A opposite to DIE Sub#1B.
2. Al-Senaeyah BSP – DIE Sub # 1B
Provide and install approximately 1.8 km 24 cores, single mode, non-metallic underground fiber cable along with the 69kV cable in PVC duct/sub ducts from Al-Senaeyah BSP to DIE Sub#1B.
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Utilize 25mmФ sub duct available in duct bank system from hand hole HH#A up to control room to route the underground fiber optic cable at DIE Sub #1B.
3. DIE Sub#1B to DIE # 1A
Provide and install approximately 1.3 km 24 cores, single mode, non-metallic underground fiber cable along in PVC duct/sub ducts between DIE Sub#1A and DIE Sub#iB.
Utilize spare 25mmФ sub duct available in duct bank system between DIE Sub # 1A and DIE Sub # 1B to route the underground fiber optic cable.
4. Al-Senaeyah BSP –DIE Sub# 2A
Provide and install approximately 1.0 km 24 cores, single mode, non-metallic underground fiber cable along with 69kV cables in PVC duct/sub ducts from Al-Senaeyah BSP to DIE Sub #2A
Spare conduits/subducts available from existing handhole # HH-13 up to 69kV basement will be utilized to route the fiber optic cable inside DIE 2A substation.
B. ARAMCO
The second case is for establishing overhead transmission lines for Aramco. This part is divided into three sections in order to discuss the process from different angles. The first one is the systems requirement. The second one is the planning process and finally the third one is the objectives and output of the project.
System Requirements
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During the planning of the transmission line for Aramco, there were many types of requirements that must be used in order to make the process a success. In this part, these requirements are presented and discussed.
First of all, all components, materials and required work for the satisfactory completion of the project and other accessories covered under the succeeding scope of the project are supplied and installed according to the planning phase. In addition, the engineering design, materials specifications and installation of materials supplies under the project are in accordance with the SOW/TS and Aramco’s standards. However, if there is a conflict between the two types of standards, then a meeting must be held to discuss the best solution. Moreover, the material specifications specified herein are to be considered as the minimum requirements and the bidders shall carry their own basic detailed designs necessary for their proposal specification. The detailed design must be finalized through design conference based on guideline drawings issued hereof, manufacturer’s drawings, calculation data sheet and others.
The project includes many things such as:
1. Mobilization2. Soil investigation and analysis3. Line route survey checks and structures staking4. structure spotting5. Design, fabrication and erection of the 230kV and 115kV
steel structures6. Supply, procurement, inspection, testing storage and handling
of required materials7. Transportation and delivery of all materials to the work site8. Construction of access roads, finger roads and structure pads.
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9. Installation of conductors, OPGW, OGW, spacer dampers, vibration dampers, joint boxes and associated hardware and accessories.
10. Design, testing and construction’s grounding system.11. Design, fabrication and installation of steel bayonet
along the existing wood frame structures.12. Reinstatement of damage concrete asphalt due to
construction activates.13. Testing and commissioning14. Demobilization and clean up.
The project that has been made for Aramco involves the construction of the following overhead transmission lines:
1. Approximately .6 km of 320kV O/H T/L looping in and out of the proposed Juaymah 230/115k BBSP, using 2-795 of kcmil ACSR/AW “Dark” conductors per phase. One of the existing circuits (circuit A) of the 230kV Ghazlan-Ras Tanura D/C O/H T/L will be cut and loop in and out of the new Juaymah 230/1150kV BSP.
2. Approximately 3.5 TOL km of 115kV D/C T/L using 1-795 kcmil ACSR/AW “Darke” conductor per phase, from the new Huaymah 230/115kV BSP up to the Qatif GOSP-1.
3. Approximately 7.0 km of 115kV O/H on double circuit steel structures using 1-795 kcmil ACSR/AW “Darke” conductor per phase from the new Juaymah 230/115kV BSP to Abu Sa’fa Transition Area.
4. Approximately .5 kilometers (total o two lines) of 115kV D/C O/H T/L s/CSIN TOL double circuit steel strcuutres of 1-795 kcmil ACSR/AW “Darke” conductor per phase. The proposed overhead transmission line shall be connected to the exiting 3 overhead transmission lines to provide three circuit connections from the proposed 230/115kV BSP to Juaymah Sub .50.
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5. Approximately 1.0 kilometers of 115kV D/C O/H T/L on double circuit steel srtcuutres using 2-336.4 kcmil ACSR/AW “Oriole” conductors per phase. The proposed O/H T/L shal be connected to the existing 115kV Juaymah to Qatif Booster Substation o/H t?l.
6. Modification of existing 230kV Ghazlan-Ras Tanura 230kV O/H T/L near Ghazlan Power Plant, approximately 1.0 km long, using 2-795 kcmil ACSR/AW “Drake” conductor per phase. The existing 230kV O/H T/L shall be diverted and reconnected to the new gantry positions inside Ghazlan Power Plant Switchyard.
In addition to that, the project also includes the retrofitting of existing conventional overhead ground wire and OPGW (230kV, O/H T/L Ghazlan-Ras Tanura Sub. 80), installation o OGW and steel bayonet, installation of OPGW on the following proposed O/H T/L
1- Juaymah 230/115Kv BSP-GOSP-12- Juaymah 230/115kV BSP-Juaymah Sub 50 c3- Qatif Booster of Qatif GOSP-2 and installation of U/G
NFOC.
Planning Process
The basic design phase of the project is a 10 to 12 week period of preliminary engineering. The purpose of the project base design work is to completely define the project in sufficient detail, to satisfy the company that all requirements are understood and are being incorporated. Information developed under the base design shall be used as guide throughout the project. The base design package will include:
1- Major material purchase requirement2- Design drawings, design calculations and other documents
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3- Manufacturer’s literature, specifications, brochures, drawings and completed material data schedules.
4- Loss prevention program5- Site security plan6- Site-pre-commissioning and commissioning tests and plan7- Schedule of required outages8- Site project plans.
Objectives And Output
There are five types of overhead transmission line work that have been done for Aramco. These five lines are as the following:
A. 115kV Overhead Transmission line from New Juaymah 230/115kV BSP to Qatif GOSP:
1. Construction of approximately 3.8 km of 115kV double circuit overhead transmission line on double circuit steel monopole structure using 1-795 kcmil “Darke” 26/7 ACSR/AW conductor per phase with 1-24 core OPGW conventional overhead ground wire (24kA fault current capacity at 0.30 sec at 50 C initial temperature) from New Juaymah 230/115kV BSP to Saudi Aramco Qatif GOSP-1. The conductor OPGW and OGW will be terminated at the proposed gantries at both ends.
2. The last O/H T/L structure before the gantry structure will be anchor type structure. The grounding of the anchor structure will be connected to the grounding grid of the substation.
B. 115kV Overhead Transmission line from New Juaymah 230/115kV BSP to Sa’fa Substation.
1. Construction of approximately 7.0 km of 115kV single circuit overhead transmission line on double circuit steel monopole structure using one 795 kcmil “Darke” 26/7 ACSR/AW conductor
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per phase with two conventional overhead ground wire (24kA fault current capacity at 0.30 sec at 50 C initial temperature) from New Juaymah 230/115kV BSP to Abu Sa’fa. The conductor OPGW and OGW will be terminated at the proposed gantries at both ends. One circuit position which s the left side acing New Juayamh 230/115kV BSP must remain vacant.
2. The last O/H T/L structure before the gantry structure will be anchor type structure up to the gantry for shielding purposes.
C. 115kV Overhead Transmission line from New Juaymah 230/115kV BSP to Juaymah Substation 50:
1. Construction of approximately two 0.80 km of 115kV double circuit steel monopole overhead transmission lines using 1-795 kcmil “Darke” 26/7 ACSR/AW conductor per phase.
Line-1 should be two circuits with 1-24 core OPGW (24kA fault current capacity at 0.30 sec at 50 C initial temperature) and one conventional overhead ground wire (24kA fault current capacity at 0.30 sec at 50 C initial temperature).
Line-2 should be one circuits and one circuit position (right side facing New Juaymah 230/1115kV BSP) should remain vacant. Two conventional overhead ground wire (24kA fault current capacity at 0.30 sec at 50 C initial temperature).
2. The last O/H T/L structure before the gantry structure will be anchor type structure. The grounding of the anchor structure will be connected to the grounding grid of the substation.
D. 230kV Overhead Transmission Line Looping in and out of New Juaymah 230/115/kV BSP from Ghazlan Power Plant and Ras Tanura Substation 80.
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1. Cutline circuit “B” between structure #32 and #33 of the existing Ghazaln Power Plant-ras Tanura Sub. 80 230kV overhead transmission line is used. This Circuit is diverted to the New Juaymah 230/115kV BSP to loop in and out of the New Juaymah 230/115kV BSP using steel monopole structure approximately .60 km with two 795 kcmil :Darke: 26/7 ACSR/AW conductor per phase and 2-24 core OPGW (24kA fault current capacity at 0.30 sec at 50 C initial temperature). This diversion will creat new circuit connection from Ghazlan Power Plant to New Juyamh 230/115kV BSP and New Juyamh 230/115kV BSP to Ras Tanura Sub. 80.
2. The last O/H T/L structure before the gantry structure will be anchor type structure. The grounding of the anchor structure will be connected to the grounding grid of the substation.
E. 115kV Overhead Tramission Line From Juyamh Power Plant-Qatif GOSP-2:
1. Construction of approximately 1.0 km of 115kV double circuit overhead transmission line on double circuit steel monopole structure using two 336.4 kcmil “Oriole” 30/7 ACSR/AW conductor per phase with one core OPGW (24kA fault current capacity at 0.30 sec at 50 C initial temperature) and one conventional overhead ground wire (24kA fault current capacity at 0.30 sec at 50 C initial temperature) from the existing steel monopole structure up to Saudi Aramco Qatif GOSP-2. The conductors, OPGW and OGW will be terminated at the proposed gantry at Qatif GOSP-2 Substation.
2. The last O/H T/L structure before the gantry structure will be anchor type structure. The grounding of the anchor structure will be connected to the grounding grid of the substation.
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CONCLUSION
In this report, there are many important aspects about power transmission planning that have been discussed. The report mentioned the need for electricity for many different areas. This is followed by discussing system modeling and requirements. And then, it discusses the modeling of power system components. Finally, the report discusses two cases about power transmission planning. These two cases are about Al-Senaeyah and Aramco.
