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  1. 1. 06/04/35 1 EEET 426 ELECTRICAL DISTRIBUTION TECHNOLOGY Dr.A.Arunagiri Distribution System Planning Chapter 1
  2. 2. 06/04/35 2 Chapter Outline Introduction Factors affecting distribution system planning Present distribution system planning techniques Distribution system planning models Computer central role in distribution planning Impact of dispersed storage and generation Renewable resources of generation Dr.A.Arunagiri Introduction Dr.A.Arunagiri The electrical power system is very complex system. Distribution is about 50% of the capital cost of the power system. The power system consists of three main parts Generation plants, Transmission and Distribution. The electrical distribution system is a part of the system between the transmission and the consumer service point. The electrical distribution system is divided into primary and secondary distribution.
  3. 3. 06/04/35 3 Typical Electrical Power System Dr.A.Arunagiri The electrical distribution systems consists of: Dr.A.Arunagiri 1.Sub transmission 2.Distribution substation 3.Primary feeders 4.Distribution transformers 5.Secondary circuits 6.Service drops
  4. 4. 06/04/35 4 Distribution System Dr.A.Arunagiri Sub-transmission Dr.A.Arunagiri The sub-transmission is an electrical network designed to supply the electrical power from the bulk power source (Transmission line) to the distribution sub-station at a voltage ranging from 33 to 220 kV. May be over head or underground cables. There are six types of sub-transmission are: • Radial system. • Primary Loop System. • Primary Selective. •Secondary selective • Spot Network • Grid Network
  5. 5. 06/04/35 5 Radial Systems Dr.A.Arunagiri Dr.A.Arunagiri
  6. 6. 06/04/35 6 Primary Loop System Dr.A.Arunagiri PrimarySelective System Dr.A.Arunagiri
  7. 7. 06/04/35 7 Secondary Selective System Dr.A.Arunagiri Spot Network Dr.A.Arunagiri
  8. 8. 06/04/35 8 Grid Network Dr.A.Arunagiri Electrical Power System Dr.A.Arunagiri
  9. 9. 06/04/35 9 Dr.A.Arunagiri Dr.A.Arunagiri
  10. 10. 06/04/35 10 (b)Single Wire Earth Return (SWER) Dr.A.Arunagiri Dr.A.Arunagiri
  11. 11. 06/04/35 11 Dr.A.Arunagiri Dr.A.Arunagiri
  12. 12. 06/04/35 12 Dr.A.Arunagiri Types of Distribution System (a) Single Phase Dr.A.Arunagiri
  13. 13. 06/04/35 13 (C ) Three phase Three Wire Dr.A.Arunagiri (d) Three Phase four Wire Dr.A.Arunagiri
  14. 14. 06/04/35 14 Basic Distribution Systems • Radial • Primary Loop • Primary Selective • Secondary Selective • Spot Network • Grid Network Dr.A.Arunagiri Factors Affecting Distribution System Planning  Load demand and load characteristics  Voltage level at the customer point  Type of secondary circuits  Size and location of distribution transformer  Types of primary distribution system  Loads at primary distribution level  Size and location of distribution substation  Routing and capacity of associated sub- transmission lines Dr.A.Arunagiri
  15. 15. 06/04/35 15 Factors Affecting Distribution System Planning…….  Restrictions such as  Permissible voltage deviations  Voltage dip and flicker  Service continuity and reliability  Types of protection to be employed  Choice of circuit breakers, reclosers and sectionalizers  Requirement of capacitors for power factor correction and loss minimization  Requirement of voltage regulators  Types of transformers and availability of space for transformers  Insulation levels Dr.A.Arunagiri Distribution system Planning Technique  Load flow programs  Radial or loop load flow programs  Short-circuit programs  Voltage drop calculation programs  Total system impedance calculation programs  Load forecasting programs  Voltage regulation and regulator setting programs  Capacitor planning programs  Substation optimal sitting and sizing programs  Reliability programs Dr.A.Arunagiri
  16. 16. 06/04/35 16 However, in general, the overall concept of automatically using output of each program as input for the next program is not in use. Engineering judgment and trial and error method are used in system planning. In this chapter, we shall discuss some of the distribution planning and operation techniques. Dr.A.Arunagiri Future Distribution System Planning Components Vision: A clear vision for the future communicates a sense of the kind of organization, power utility needs to become, and outlines the kind of results it must achieve. The vision provides a continuing focus and constantly reminds the employees and consumers of what the company trying to change.  Mission: For particular task there can be a mission statement such as Electricity for all KSA by the end of next decade  Values: The power utility leadership must create values such as consumer satisfaction, environmental responsibility. Dr.A.Arunagiri
  17. 17. 06/04/35 17 Distribution system planning models Traditional-Least cost model: It is a process by which utilities minimize the cost of supplying a given amount of power. The existing system inadequacies are identified as: • Poor voltage regulation • Higher system loss • Higher equipment failure/breakdown • Bad quality of power supply • No scope for future growth. Dr.A.Arunagiri The initial system improvement can be very cost effective in removing the above system inadequacies as compared to the other alternatives of laying a new extended system. Thus there are two options:  System improvement  Expansion of the existing network Dr.A.Arunagiri
  18. 18. 06/04/35 18 (a) System Improvement Augmentation and strengthening of the existing system Improving the reliability and quality of supply Reduction of commercial and technical loss and / or Dr.A.Arunagiri b)Expansion of the existing network When augmentation and strengthening of existing system are involved the benefits of saving in losses (kw and energy), net revenue increase due to additional sale of power and energy after adjusting the expenditure incurred on generation of the additional energy must be maximized. Dr.A.Arunagiri
  19. 19. 06/04/35 19 2. Demand Side Planning(DSP) It is the process by which power utilities quantify and assess the programmes to alter the load pattern and level of their consumer’s demand for electricity. This is planning at the consumer level and often has a long planning period, much longer than distribution system planning. It can take years of slow progress to obtain meaningful levels of participation. Dr.A.Arunagiri The low cost demand side option can be : Implementing energy conservation programmes Providing vigilance and detection of theft. Dr.A.Arunagiri
  20. 20. 06/04/35 20 DSM programmes generally fall into three main categories: 1 Conservation programmes Reduce energy use with programmes to improve the efficiency of the equipments (like lighting and motors), buildings and industrial processes as per the energy conservation act. 2 load management programmes: Redistribute energy demands to spread it more evenly throughout the day. Some way of doing this are: Load shifting programmes ( shifting some of the loads during peak period to off peak period) Time -of –use ( Charging more for electricity during peak demand) Interruptible rates( providing rate discounts in exchange for the right to reduce consumers electricity allocation each year during few hours when electricity demand is the highest Types of DSM Dr.A.Arunagiri 3. Strategic load growth programmes: Increase energy use during some periods, (Encourage cost effective electrical technologies that operate primarily during periods of low electricity demand.) The following approaches can be used.  General information programmes to inform consumers about generic energy efficientoptions  Site – specific information programmes that provide information about specific DSM measures appropriate for a particular industry , agricultureor home.  Financing programmes to assist consumers to pay for DSM measures includingloans, rebates, and shared savings programmes Dr.A.Arunagiri
  21. 21. 06/04/35 21  Direct installation programmes that provide complete services to design, finance and install a package of efficiency measures.  Alternative tariff programmes including time-of-use tariff, interruptible tariff, and load shifting tariff. ( These programmes usually do not save energy but they are effective ways to shift loads to off peak periods.  Bidding programmes in which utility solicits bids from consumers and energy service companies.  Load limiters are effective in demand side management , as they limit the maximum power that the consumer draws from the supply. Dr.A.Arunagiri The process of designing and implementing DSM programmes generally consists of the following steps.  Identifying the sectors, end -uses and efficiency measures to target  Developing programme design  Conducting cost-effective screening  Preparing an implementation plan  Implementing programmes and  Evaluating programmes. Dr.A.Arunagiri
  22. 22. 06/04/35 22 Benefits of DSM • Reduces consumers energy bills • Reduces the need for the new plant, transmission and distribution construction • Stimulates economic development • Creates long time jobs that benefits the economy • Increases the competitiveness of the local enterprises • Can reduce maintenance and equipment replacement cost • Reduces local air pollution • Reduces emission s that contribute to national and international environmental problems such as acid rain and global warming • Enhances national security by easing dependence on foreign energy sources Dr.A.Arunagiri Computer central role in distribution planning  Software needs: generally is selected on the basis of the least life cycle cost or least ownership costs (hiring or purchase + training + maintenance costs). The software must be. – Bestoverallperformance – Bestsolution – Bestopen architecture system  Analysis of the system computer aided power flow studies in improving the performance of the existing sub-transmission and distribution systems and proposed expansion of network up to the meter point (Consumers). Studies will provide – Active and reactive power flows as well as the locations of capacitors – Voltage variation (at each node or bus, percent variation) – Peak power losses and energy losses – Computation of commercial losses of feeder – Overloading of transformers : Dr.A.Arunagiri
  23. 23. 06/04/35 23 Computer central role in distribution planning  Data: success of any information technology system is highly dependent on the accurate, up to date field data for improvement in the network and system. Information must be clear and up- dated on: Nodes Single line diagram Distribution substation Primary feeder Distribution transformer and secondary feeder Consumer data Load data Dr.A.Arunagiri Elements of the distribution system  Distribution Transformer  Primary distribution feeder  Secondary distribution feeder  Protection devices and instrumentation Dr.A.Arunagiri
  24. 24. 06/04/35 24 Dispersed Generation Dr.A.Arunagiri Impact of dispersed storage and generation • This is When the generating plant is connected to a distribution network capable of supplying power to the consumer load directly . • This enhances the reliability and the quality of power supply. • The expectations of the reliability especially for data centers, call centers, computer controlled critical process/businesses, continuous process industries, petro chemical refineries are four nines (99.99%). Dr.A.Arunagiri
  25. 25. 06/04/35 25 Impact of dispersed generation…. For dispersed generations line losses will be nominal since there is no transmission system is required. Dispersed generation with local radial distribution network will play an important role in the 21st century. Dispersed generation is generally from local renewable sources. This saves environment degradation compared to conventional thermal generation. Dr.A.Arunagiri Renewable resources of generation  Fuel cells  Solar photovoltaic  Wind energy  Tidal wave energy from ocean  Small hydro (up to 25 MW capacity, pumped storage)  Geo-thermal  Bio-mass  Municipal and industrial west Dr.A.Arunagiri
  26. 26. 06/04/35 26 Net Metering The kilo watt hour meter(import – export meter) can be used to accurately register the flow of electricity in either direction. This means the ‘netting’ process associated with net metering happens automatically Dr.A.Arunagiri Assignment 1 Q.1 Draw the one line diagram of the electrical power system available in KSA.. Indicate the voltage levels for Generation Transmission Sub transmission Primary Feeder Secondary Feeder Q2 Mention and discuss the different types of the renewable resources of generation available in the KSA. Dr.A.Arunagiri