Electrical Power- Distribution System

Task 1 Describe the basic topology of the national major military unit corpse earnings. The topic Grid Ne twork A national grid mesh topology is a network of cable that connects all(pre nominative) the power stations in a country to transmit galvanicity to the consumers through place the country. Electricity is in demand just about everywhere in the civilized world, and in Great Britain the network for supplying this galvanizing power is known ordinarily as the subject Grid. The National Grid is an electric power transmittal network which connects the substations and power stations.This is so that any electrical readiness generated in Great Britain, can be utilized and help meet energy demands elsewhere. This grid transcription also entangles interconnections that run under the sea to blue Ireland HVDC Moyle, the Isle of Man and France HVDC Cross-Channel. The electrical energy generated for the National grid of necessity to be moved around all parts of the country t o supply the demand. There ar two methods available for the transmittal transcription and scattering of electric power and these be * Underground Insulated Cables Overhead Cables (Bargon Conductors Susp expiryed at a Safe Height Above Ground) The bang lines are more often than not use for high- electric potential long distance transmission system, because the cost is lower than underground cables, curiously at higher potencys. In British practice, high voltage transmission lines carry voltages ranging from 66kv to 132kv, and extra high voltage lines carry voltages from 220kv to 380kv. In all cases the power is transmitted in the form of ternion-phase alternating current at 50cycles/sec, and the cost of an overhead line depends largely on theater director coat and voltage Cheesman, 2007.Figure 1 General layout of electricity networks (Diagram taken from http//en. wikipedia. org) Structure of dispersal grids The structure or topology of a grid can transmute considerab ly. The physical layout is often forced by what land is available and its geology. The dianoetic topology can vary depending on the constraints of budget, requirements for system reliability, and the load and coevals characteristics. A typical topology of a grid is shown in opine 2 below. A A Figure 2 Schematic delegacy of a stellate tire system (Diagram taken from http//www. transanatolia. eu)Figure represent a authoritative electricity dissemination grids-simple stellate tree, sending power from a get-go (point A representing power generation or a substation) to delivery points ( some other points representing categorys, businesses, or other sub networks). The cheapest and simplest topology for a diffusion or transmission grid is a radial structure. This is a tree shape where power from a large supply radiates out into progressively lower voltage lines until the destination homes and businesses are r distributivelyed. Most transmission grids require the reliability th at more(prenominal) complex mesh networks provide.Other topologies used are grommeted systems and tied ring networks. National grids are composed of many smaller electrical networks that are cogitate together into a larger network called a Wide world Synchronous Grid, also known as an interconnection. A Wide country Synchronous Grid allows all the independent electrical networks in a particular area to be affiliated by synchronizing the electrical frequency between them. United Kingdom interconnections are synchronized at 50Hz. Task 2 describe the basic topology of the ring and radial eater system. Radial Feeder SystemIn a radial configuration, lines branch out sequentially and power flows strictly in angiotensin-converting enzyme direction, only one path is connected between separately customer and the substations. The electrical power flows from the substation to the customer along a single path. If this path is interrupted, it will run in a complete loss of power to the customer. The loading of a distribution feeder is inherently unbalanced because of the large summate of unsymmetrical single-phase loads that must be served. An additional imbalance is introduced by the non-equilateral conductor spacing of the three-phase overhead and underground line segments.Figure 3 below shows the radial feeder system. Figure 3 Radial distribution system about of the advantages of this system include minimum initial cost and simplicity of planning, project and operation. Disadvantages include low reliability factor, distributor nearer to the feeding end is heavily loaded. Ring or Loop system In a ring, any two points are publicly connected by more than one path, meaning that some lines form loops within the system. This distribution system consists of two or more paths between the substations and the customers. It is selected to carry its normal load plus the load of the other half of the loop also.Therefore the size of the feeder conductor in a loop d istribution system is the aforesaid(prenominal) throughout the loop. Figure 4 below shows the ring or loop feeder system. Figure 4 Loop distribution system Advantages of this system include Less conductor material is required as each part of the ring carries less current. Less voltage fluctuations. It is more reliable. Disadvantages include It is difficult to design compared to the radial system. Task 3. For the radial feeder shown in fig. 3. 1 calculate the following 15A 15A 50A 50A B B 0. 2? 0. 2? 0. 1? 0. 1? 0. 06? 0. 06? A A 20A 20A 240V 240V D D C C Figure 3. 1 a) The load voltages resoluteness From figure 3. 1, the voltage except from A to D is VAD=0. 2IAB+0. 06IBC+0. 1ICD Current between A and BIAB=50+15+20=85A electric potential drop from A to B VA-B=0. 2*85=17V electromotive force at BVB= VA-VAB Therefore,VB=240-17=223V Current between B and CIBC=85-50=35A Voltage drop from B to CVB-C=0. 06*35=2. 1V Voltage at CVC= VB-VBC=223-2. 1=220. 9V Current between C and DICD=35-1 5=20A Voltage drop from C to D VC-D=0. 1*20=2V Voltage at DVD= VC- VCD=220. 9-2=218. 9V Therefore Voltage drop from A to D e=0. 2IAB+0. 06IBC+0. 1ICD =0. 2*85+0. 06*35+0. 1*20 VAD =17+2. 1+2=21. 1V b) The power lost in the cable. provide supplied to the system = 240 * 85 = 20400 W PLOSS = (VAB*IAB) + (VBC * IBC)+ (VCD*ICD ) = (17*85) + (2. 1*35) +(2*20) = 1445 + 73. 5 + 40 = 20400 = 1558. 5W c) The power essential by each load. major power at B, PB = VB * IB = 223 * 50 = 11150W= 11. 15KW Power at C, PC = VC * IC = 220. 9 * 15 = 3313. 5W = 3. 31KW Power at D, PD = VD * ID = 218. 9 * 20 = 4378W = 4. 38KW Total Power highly-developed = PB + PC + PD = 11150 + 3313. 5 + 4378 = 18841. 5W =18. 84KW d) The qualification of the system The efficiency of the transmission line is given by Efficiency =100% * Power supplied / (power supplied + power loss) PP+PL*100%= 2040020400+1558. 5*100%=92. 9% Task 4 Write a short treat on distribution systems. The report should include the following con tent i) The most common LV distribution systems used. ii) A diagram of the single phase 3 telegraph 240/ great hundred topology iii) Description of the single phase 3 wire 240/ great hundred development iv) The effect of unequal loading v) The advantages of the single phase 3 wire 240c/ cxxv system vi) A diagram of the three phase 4 wire 208v/120 topology vii) three phase 3 wire 600v topology, vii) three phase 4 wire 480v/277v topology. Examples of where this would be used Solution scattering Subsystem The distribution system connects the distribution substations to the consumers service-entrance equipment. There are two types of distribution system the primary and utility(prenominal) distribution system. The Primary Distribution System The primary distribution lines range from 4 to 34. 5 kV and supply the load in a well-defined geographical area. The transmission system voltage is stepped-down to lower levels by distribution substation transformers. The primary distribution syste m is that portion of the power network between the distribution substation and the use transformers.The primary distribution system consists of circuits, referred to as primary or distribution feeders that originate at the supplemental bus of the distribution substation. The distribution substation is usually the delivery point of electric power in large industrial or commercial applications Primary distribution system voltages range from 2,400 V to 69,000 V. The distribution voltages in widest use are 12,470 V and 13,200 V, both three and iv wire. Types of Primary Distribution System. There are two native types of primary distribution systems Radial and Network.Simply defined, a radial system has a single simultaneous path of power flow to the load. A network has more than one simultaneous path. Each of the two types of systems has a number of variations. Figure 6 illustrates four primary feeder arrangements showing tie, loop, radial and parallel feeders. There are other more c omplex systems, such(prenominal) as the primary network (interconnected substations with feeders forming a grid) and dual-service network (alternate feeder to each load). These systems, however, are simply variations of the two basic feeder arrangements.Some small industrial customers are served directly by the primary feeders. Figure 6 four primary feeder arrangements. (Diagram taken from www. navalfacilities. tpub. com) The secondary Distribution System The secondary distribution network reduces the voltage for utilization by commercial and residential consumers. Lines and cables not exceeding a few hundred feet in distance deliver power to the individual consumers. The secondary distribution serves most of the customers at levels of 240/120 V, single-phase, three-wire 208Y/120 V, three-phase, four-wire or 480Y/277 V, three-phase, four-wire.The power for a typical home is derived from a transformer that reduces the primary feeder voltage to 240/120 V apply a three wire line. Dis tribution systems utilize both overhead and underground conductors. The voltage levels for a particular secondary system are determined by the loads to be served. The utilization voltages are generally in the range of 120 to 600 V. In residential and rural areas the nominal supply is a 120/240 V, single-phase, three-wire grounded system. If three-phase power is required in these areas, the systems are normally 208Y/120 V or less commonly 240/120 V.In commercial or industrial areas, where motor loads are predominant, the common three-phase system voltages are 208Y/120 V and 480Y/277 V. The preferred utilization voltage for industrial plants, however, is 480Y/277 V. Three-phase power and other 480 V loads are connected directly to the system at 480 V and fluorescent lighting is connected phase to neutral at 277 V. Small dry-type transformers, rated 480-208Y/120 or 480-120/240 V, are used to provide 120 V single-phase for convenience outlets and to provide 208 V single- and three-phase for small tools and other machinery.Types of lower-ranking distribution Systems. Various circuit arrangements are available for secondary power distribution. The basic circuits are simple radial system, expanded radial system, primary selective system, primary loop system, secondary selective system, and secondary spot network. References Alley, R. and Smith, K. (1992) Electrical Circuits An Introduction. Cambridge Cambridge University Press, p. 220-236. Altenergy. org (2008) Alternative nada Wind, Solar, Hydro and other alt energy sources for home power. online ready(prenominal) at http//www. ltenergy. org/ Accessed 19 Jun 2012. Cheesman, J. 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Most. gov. mm (2011) Transformer Operation and system voltage control. online Available at http//www. most. gov. mm/techuni/media /EP_04018_2. pdf Accessed 17. 06. 12. Navalfacilities. tpub. com (n. d. ) Secondary Voltage Levels. online Available at http//navalfacilities. tpub. com/mo201/mo2010022. htm Accessed 19 Jun 2012. Sivanagaraju, S. and satyanarayana, S. (2009)Electrica l Power contagion and Distribution. New Delhi Pearson Education, p. 479-512. Transanatolia. eu (2007) Electrical Grid. online Available at http//www. transanatolia. eu/analyses/Energy/electrical-grid. htm Accessed 19 Jun 2012.