Power Distribution Systems - Report Example

Power Distribution Student Name Instructor College Course Name Outline Introduction Distribution system layout Alain distribution system layout Distribution system substation and equipment Summary References Introduction The department visited during tour study was maintenance department. The main reason for visiting this department is because it’s responsible for maintaining power distribution systems that has already installed. This department handles all power distribution systems and they do all manner of repairs including replacing a distribution system and equipments. During my visit to the department i met the department as well as the field officer who introduced me to other members of the department. The two gentlemen explained to me that the distribution system dependent on the geographical locations. They told me that most urban areas use underground cables while in rural areas overhead lines are used. These systems are chosen in these geographical locations because of safety, cost effectiveness and flexibility of the system. The other factors that are considered during choosing the system that will be used in distribution of power include continuity of supply, minimum investment, minimization of maintenance cost, maximization of electrical efficiency and quality of supply. Transmission lines are those lines that transmit power in high voltage which can not be consumed directly. It takes power from step up substations to step down substations. The distribution system is where power is distributed to consumers from step down substations. It can be primary distribution or secondary distribution. This is shown in the diagram shown above. Distribution system layout When power comes in from transmission system to substation is transformed by stepping down high voltage power by transformers to have power that can be distributed. The distribution layout that is adopted by company has switches, breakers, Reclosers, fuses and feeders. In the substation there are switches that are used to offer protection in case there is a problem and there is need to interrupt normal supply by disconnecting a certain line. However when there is fault current, circuit breakers have been installed to interrupt the flow of current. They sensors that detects short-circuit before interrupt. There are devices used in lockout called reclosers which have ability to reclose and open continually until the circuit is completely interrupted. They automatically reclose a circuit breaker when there fault in power distribution ensuring that there is no current in the circuit. Within the distribution system there are fuses which carry defined currents and they spoilt when there is short-circuit currents. The switches and other devices for protection are installed on both sides of the transformer within the substation. The figure below shows a distribution substation with high reliability which uses many circuit breakers; This diagram above shows that feeders are supplied with power from a transformer or a sub-transmission line outages. However we can have another system that utilises protection devises in series in conjunction with feeders as shown below; In these diagrams we can note that protective devices are closed except in the instances where it is indicated normally open (NO). In the substation there are voltage regulators to ensure the flow of current flow from the source along the feeder is dropped to fit the length of feeder. The figure below shows the voltage at the substation and how it is regulated to end of the feeder. A switch is mostly used to overcome the problem of maintenance in one area and the effects on the supply when there is fault in the substation. With a switch, primary feeder are able to transmit simultaneously for instance, in the case of fault. The switch is able to read the destination addresses and then switches the signals directly to the feeders without closing unless reclosers are used. Figure 3: feeder load variation The figure above shows that when there is a load increase, the voltage at end of feeder will drop. This means that voltage is regulated when load on feeder varies, this ensured by load tap-changing transformers which can be inform of feeder or fixed or switched shunt capacitors, bus voltage regulators and line voltage regulators. When there is power is leaving the substation there is a meter which measures amount of power that leaves to ensure the maximum is not exceeded or the minimum is not reached. This ensures that power is supply at the correct load to final consumer. The following is sketch of the distribution line to the final consumers from a substation Overhead Underground This distribution line shows that power is loaded to the feeders from substation to ensure reliability in supply. Alain distribution system layout The power distribution system is called radial where power is receives and stepped down to ready for consumption. The diagram below shows has power is distributed after step down In this case above, a high-voltage power holding 3-phase transformer which can withstand a capacity of 630 kV/10.5 kV. Such transformers contain iron core solenoid and other high-voltage resistant materials such as stainless steel. These stainless steel materials get enforced by silver materials coated by polyimide films. This combination has allowed generation of modern electrical transformers which can withstand high electric voltage as well resistance to high temperatures. We have a modern electric transformers which have an automatic and modern cooling system have been developed. These transformers have replaced the old antiquated transformer which used circulating cooling oil in small metallic pipes. In the supply of power to customers may take many forms as shown above where the customer receives power from secondary lines and there is no step down transformers that are required. However there are instances where the customer receives power from the primary lines without transformers in that case there is equipment along the system that acts as switch, switchboard, transformer, and low voltage switchgear. The equipment in question looks like outdoor pad-mounted transformer which has fused switch as well as breaker feeding switchboard. While in the secondary line there is low voltage switchboard or switchgear, transformer, primary switch and breaker feeding. It was noted a secondary substation is required in case the customer is supplied from the main system which has a fused switch, switchboard or switchgear and transformer that are installed in ‘close-coupled single assembly’. The main distributed as shown below when consumers are supplied from the secondary system Each secondary system emanates from a transformer which is situated in an area where it can a certain number of consumers and when supplying a customer, the loading capacity of a transformer is considered. Distribution system substation and equipment The substation equipments which assist in power distribution include transformers, surge arrestors, circuit breakers, current limiting reactors, horn-gap switch, disconnect & grounding switch relays and protective devices. A substation should have sufficient capacity to serve some customers. When power leaves the substation id feed to transformers that step down power to consumable level, however the number of transformers that are required per primary feeder is reduced by feeder circuits that are used. This ensures that there is continuity of supply and flexibility in supply of power. Owing to the demands and the nature of consumption, the need for a distribution system has become critical. In fact, any fault in either the equipment or line can result to downtime cost on the customers. However, designing and implementing a distribution network would moderate the failure of the entire system as a result of failure. In addition substation is also critical in the supply because it allows power to be controlled by the department. This will drastically diminish the cost, but also decrease the level of conductor and equipment protection. Thus, should a fault or overload condition occur, downtime increases significantly and higher costs associated with increased damage levels and the need for fuse replacement is typically encountered. In most cases, the department opt for a substation if their intention is to prevent any form of outages or reduce the power failure. In such circumstances, it becomes hard for an department to design a distribution network not unless it is ready to offer the required and appropriate maintenance as well as incorporate any possible improvements that might be necessary during the designing process. Owing to such technicality, a successful design for a distribution network would not only taking into account, but also ensuring that various components that are critical in the distribution system are incorporated into the system. Summary During my visit to the station to understand electrical power distribution systems, I learnt a number of practical things which I had only theoretical knowledge. I was able to go around the department where I understood further how the distribution system operates. The visit may appear simple in its own but very complex when it comes to realization of what was to be learned. It is safe to state that my knowledge in distribution system improved immensely. Firstly, the tour made me appreciate the importance of substations in power distribution system. While I considered distribution systems in terms of poles and wires, insulators and lightening arrestors as very important, now i understand that they should be accompanied by substations for convenience and safety of power uses. I also realise that I’m very fortunate to have undertaken this course which relates to lighting the world. Power distribution system has benefited the world by supplying power to individuals and corporations. This was confirmed by discussion with the head of the department which i visited. As I stated on the narration, visiting the department allowed me to understand the practical side of power distribution. I learned that power distribution requires all equipments that i learned theoretically. Thus I come to the conclusion that while theoretical perspective of study is important, it is necessary to have practical knowledge of the distribution system otherwise there will be no difference between a lay man in the field of engineering, a graduate without practical knowhow. With regard to conducting my tour, I found out that noting down points was very necessary. I’m often confronted by my thoughts when carrying out my research can distract my exploration. In the context of this assignment, note-taking proved to be helpful since notes and impressions that I wrote down helped me during the organization of my report. This means they acted as cues for me to remember what i saw during exploration thus preserving clarity and accuracy of the moment and allowed me to revisit with a well informed hindsight. The exploration has enabled me have the ability to think independently, improving my individual and interpersonal skills. I have managed to assess my capability, determining my response to different situations. This also acted as a preliminary practical experience that I may encounter in future thus very important. My visit to the department will be more beneficial when I will liaise with maintenance department to know when they are carrying out maintenance so that I can spend the whole with them. This will be more beneficial than the act of visiting and asking questions. References Bayliss, C. & Hardy, B. (2012). Transmission and Distribution Electrical Engineering. New York: Newnes Blume, S. (2010). Electric Power System Basics for the Nonelectrical Professional. New York: Wiley-IEEE Press; Chan. F. (2011). Electric Power distribution systems. Retrieved December, 30, 2012, from Eaton (SEPT, 2011). Power Distribution Systems System Design. Retrieved December, 30, 2012, from Grigsby, L. (2007). Electric Power Generation, Transmission, and Distribution. New York. CRC Press. McDonald, J. (2007). Electric Power Substations Engineering. New York: CRC Press MMME2104. (August 2003) Transmission and Distribution. Retrieved December, 30, 2012, from Read More