Fault location methods

Fault location methods Abstract This paper presents a comparative study between two fault location methods in distribution network with Distributed Generation (DG). Both methods are based on computing the impedance using fundamental voltage and current signals. The first method uses one-end information and the second uses both ends. A 30 kV three-phase line was studied in the presence of a 3 MW fixed speed wind turbine. Index Terms-Fault location, Distribution network, Distributed Generation, Fixed Speed Wind Turbineà ¢Ã¢â€š ¬Ã‚ ¦ Introduction Fault location problem in transmission networks has been studied deeply because of its importance in the power system and because its difficult to physically check long transmission lines [1]. Nowadays, the problem of fault location was extended to distribution network in order to identify the fault location as quickly as possible to improve the power quality and the system reliability. The application of classical techniques, presented in Section 2, is not easy due to the complexity of the distribution systems which are characterized by the non-homogeneity of line, the load uncertainty, the phase unbalanceà ¢Ã¢â€š ¬Ã‚ ¦ [2] Fault location problem in the distribution network becomes more complicated with the presence of the Distributed Generation (DG). In fact, the DG resources, connected to the distribution system, which are in general, wind turbines and small hydro-electrical plants [3], contribute to the fault level of the network and their effect depends on their size, type and placement [4]. The infeed currents from the DGs cause errors in the estimation of the distance of the fault point since they can affect the amplitude, the direction and, indirectly, the duration of fault currents [3]. In this paper, we present two fault location methods which have been successfully applied to a real fault that occurred on a 225 kV transmission line in [5]. They will be, first, tested on a simple distribution line without DGs. Then, we consider a fixed speed wind turbine connected to the other side of the line. FAULT LOCATION TECHNIQUES Fault location methods can be classified into different categories: Methods based on travelling waves in faulted line: in [6], authors present a travelling wave based fault location method, which was successfully applied on a transmission line, and extended to distribution line with DGs. The main advantages of this approach are its insensitivity to the contribution of the DGs during fault and the requirement of fault signal only from the substation end of the faulted line. Methods based on harmonics analysis: those methods are not frequently used since grid operators have the aim to reduce harmonics in the power system. Method based on computing the short circuit power, using the voltage and the currents, to determine the fault location [5]. Method using instantaneous voltage and current available at both ends of the line [5]. Methods based on determining the apparent impedance using the fundamental components of voltage and current: this method is the most widely used because of its simplicity and efficiency, and it does not require a big investment in equipment [1], [2]. Those methods can be divided into two groups: Methods using one-end information and Methods using both ends of the affected line. Fig. 1 shows a simple three-phase distribution line with a load connected via a transformer (30 kV/ 575 V). The basic approach used for determining the fault distance d is to calculate the impedance seen from substation (NL) during the fault. This paper presents two fault location techniques. Method using one-end information Where: Vk is the voltage of the faulted phase and Vf is the fault voltage. Vk and Vf depends on the fault type as given in table I. Method using both ends information The voltage and the current of the two ends line are related with this expression: Where: VLi, VRi, ILi, IRi are resp. the voltage and the current of the left and the right side of the phase i. VLj, VRj, ILj, IRj are resp. the voltage and the current of the left and the right side of the phase j. Zik,Zjk: elements of the impedance matrix of the line L: line length d: fault distance Simulation and results In order to show the effectiveness of the presented algorithms, the system presented in Fig. 1 is tested with the source, the line and the load parameters given in table II. Where: dest and dreal are respectively the estimated and the real fault distance, and L is the line length. Fig. 2 shows the estimated error for the simulated system of Fig. 1 for different fault resistance value to compare the two techniques described above. Fig. 3 shows the fault location results for different load power. It can be seen that as the load power increases, the estimation error also increases. For the first technique, the estimation error is less than 1.5% and can still be acceptable, but for the second technique, the estimation error can reach 30% for a 5 MW load. In fact, the accuracy of the algorithm, for variable load, depends on the short-circuit power of the source. Fig. 4 shows that the estimation error decreases if the ratio between the load power and the source short-circuit power decreases. In order to study the influence of the integration of the DGs into the distribution networks on the fault location accuracy, a three-phase line integrating a 3MW fixed speed wind turbine at the right side of the line is considered in Fig. 5. A 1MW local load has been connected to the WT. Fig. 6, 7 and 8 present the WT characteristics: the nominal wind speed is 9 m/s; the wind speed is imposed equal to 8 m/s that makes the WT generating 0.66 pu of its active power. The reactive power is generated by an 800 kVAR capacitors. The WT speed is fixed to 1 pu. A one-phase fault, during 600 ms, that occurs on the line with different fault resistance value and different load power, is used to evaluate the presented methods. Fig. 9 presents the estimated error for the simulated line with wind turbine. It can be seen that the error is higher than in the first case because of the participation of the WT to the fault current which is not delivered only by the source. Then, the source voltage increases and the impedance seen from the source will be higher than the impedance of the same fault on the line without WT. Comparing with the results presented for a line without DGs, we can see that the contribution of the WT in the fault current increases widely the estimation error of both methods, especially the second one that uses the recorded information from the source bus and the WT connection point. The effect of the uncertainty of the load is investigated by varying its value from 0 to 5 MW, for a fault located at 20 km from the source. Fig. 10 presents the accuracy of the described methods while varying the load. Unlike the result presented for the line without GDs, the estimated error decreases while increasing the load impedance. This result shows that conventional methods cant be well used for network with DGs. It is known that an increase in generation capacity, increases the fault current, then the participation of the DGs to the fault level will increase too. For that, we consider two wind turbine of 3MW each one, connected to a distribution network at the same connection point. The wind reference of the first WT is fixed to 8m/s, and for the second, it starts with a wind speed of 8m/s then it increases to 9m/s to simulate the two wind sources with different rate of penetration. Fig. 12 shows the characteristics of both WTs. Conclusion This paper presents two impedance based fault location methods tested on a distribution line with and without distributed generation. The two techniques present an interesting precision for fault location in distribution system that does not integrate GDs. But, with the existence of the WT connected to the grid, those methods are not applicable especially for a high fault resistance value or variable load impedance. Thus, integration of the DGs into the distribution network requires further study on the existing fault location techniques to adapt them with the DGs state when a fault occurs. References J. Mora, J. Melendez, M. Vinyoles, J. Sà ¡nchez, M. Castro, An Overview to Fault Location Methods in Distribution System Based on Single End Measures of Voltage and Current, Journal Name, vol. 1, no. 3, pp. 1-10, Mar. 2000. Y.-J. Ahn, M.-S. Choi, S.-H. Kang and S.-J. Lee, An accurate fault location algorithm for double-circuit transmission systems, in Proc. IEEE Power Eng. Soc. Summer Meeting, vol. 3, 2000, pp. 1344-1349. TH. Boutsika, S. Papathanassiou, N. Drossos, Calculation of the Fault Level Contribution of Distributed Generation According To IEC Standard 60909, NTUA-Electric Power Division, Athens. V.R. Kanduri, Distributed Generation Impact on Fault Response of A Distrubution Network, Thesis of the Faculty of Mississippi State University, 2004. A. Abadlia,La Localisation des Dà ©fauts dans les Lignes Electriques, Thesis of the National School of Engineers of Tunis (ENIT), 2007. C.Y. Evrenosoglu, A. Abur, Fault Location in Distribution Systems with Distributed Generation, 15th PSCC, Liege, 22-26 August 2005, Session 10, Paper 5, p. 5.

The Impact of Global Warming on Human Health Essay -- Environmental Gl

The Impact of Global Warming on Human Health   Ã‚  Ã‚  Ã‚  Ã‚  Throughout the world, the presence of particular diseases and other threats to human health depend largely on the local climate. Extreme variation in temperature can directly, and indirectly, cause the loss of human life. The threat of a gradual increase in temperature could be catastrophic to the world, as we know it. In 1999, a heat wave killed more than 250 people in Chicago alone (Union of Concerned Scientists). Many consider such an event as a natural disaster. However, scientists warn the average global temperature has increase 0.5  ° F in the past 40 years. This is half of the total increase in surface temperature, 1 °F, since the late 19th century. At its current rate, the global temperature could rise 2 ° to 6 °F in the next 100 years (Union of Concerned Scientist).   Ã‚  Ã‚  Ã‚  Ã‚  Such a drastic increase in the rate of temperature increase is due to the industrial revolution. In the past 40 years, the world has seen a drastic increase in population and the use of fossil fuels (gasoline, oil, coal or natural gas). These fuels are used to run our cars, heat and cool our homes, manufacture goods in our factories and to ship goods for worldwide consumption. The focus, until lately, has been to produce maximum product at a minimum price to maximize profit. Little to no care was taken to minimize the amount of fossil fuels used in the production of goods. Recently, it has become evident that such practices lead to the production of greenhouse gases. Whenever fossil fuels are burned for energy, greenhouse gases, such as carbon dioxide builds up in the earth’s atmosphere (Union of Concerned Scientists).   Ã‚  Ã‚  Ã‚  Ã‚  Another reason why greenhouse gases have increased is due to the decrease in the amount of plant life, commonly called deforestation. Plant life is the only thing known on earth to consume carbon dioxide. However, due to the need of raw materials (wood and paper pulp), industrial nations tend to cut down more trees than they can reforest (Fuller 454). Also, toxins produced as a by-product of industrialization have killed plant life. Therefore, a greater amount of carbon dioxide is being produced at the same time less carbon dioxide is being consumed, leading to dangerous consequences.   Ã‚  Ã‚  Ã‚  Ã‚  The combination of pollutants and deforestation has lead to what is commonly called the Greenhouse Effect. The term... ...ure on the government to create legislation that will save the environment as well as keep our energy rates low and stable. Such legislation is almost impossible. A good first step for the government would be to create effective, mass public transportation such as the train and subway systems of Europe. However, we the residents of this planet, also must do our part to reduce our role in polluting the environment. After all, we are the ones who have to live with, or die from, the consequences of our actions. Works Cited Buchholz, Rogene A. Principles of Environmental Management. (1984). Christianson, Gale E. Greenhouse: The 200-Year Story of Global Warming. (1999). Fuller, Jim. â€Å"Ministers Unable to Reach Agreement at Climate Change Conference†. November 25, 2005. Http://globalchange.gov/news/hague_conference_2005_1125.html Leggett, Jeremy. The Climate Time Bomb: Signs of Climate Change from The Greenpeace Database (Amsterdam, Netherlands: Stichting Greenpeace Council, 1994). Revkin, Andrew. Global Warming: Understanding the Forecast.(2004). Union of Concerned Scientist. â€Å"Safeguarding the web of life: Global Environment†. June 29, 2006. http://www.uscusa.org

Analysis of The Shifting Heart, by Richard Beynon Essay

Thesis: In The Shifting Heart, the playwright Richard Beynon conveys ideas and representations of Australian identity through the use of narrative techniques, especially dialogue and characterisation. Each character represents an aspect of Australian society in the 1950’s that Beynon perceives to be true. 1st published in 1960. Set in 1956. NUTSHELL- 1. Not accepting of other cultures; Abuse against Gino and failed assimilation halfway between identities. Cultural heritage is important in establishing identity -Through the characterisation of Gino, Beynon shows the rejection of Australians towards immigrants and other cultures. -Page 95 Australian citizenship Certificate shows the belief Gino had that he had been accepted into Australian society. Momma â€Å"This we gotta put in a frame, he says.† It means something to him. Constant beatings he receives at the dance hall show that he is not accepted, as well as Barry shoving in the way in line â€Å"He tries to put his load straight on the scales- before us, so I told him†¦Ã¢â‚¬  Clarry: â€Å"You shouldn’ta told him (page 27). Eventual death of Gino via the beatings shows the extreme racism and prejudice in Australia during the time of production. -Assimilation is encouraged to fit in -He tried to assimilate into Australian society, Pg 34 â€Å"Clarry. If he’s Australian, or†¦Ã¢â‚¬  and then continues on page 35 â€Å"Maria. Italian? (Pressing hard) What if he’s†¦ between the two?† 2. The play explores the systemic racism that exists within Australian society and portrays the justice system as corrupt and discriminatory -Throughout the play it is evident that racism is widespread and commonly used, with the people supporting immigrants being the minority. -After the death of Gino, it is evident that the law system is corrupt and that racism is systemic. -Detective Lukie- Boss is looking to promote him if he successfully pins the fight on the dead Gino. Page 69 rank is Detective sergeant (high ranking). Corrupt- makes assumptions, takes one side of the story of the Australian, â€Å"All I know are the facts,† page 73. Biased and racist Witness girl saw it all unfold page 96 the girl Gino was meeting on Italians side: Lukie â€Å"And we found a girl, too; arranged to meet him in the foyer. Saw most of it happen, she says†¦Ã¢â‚¬ - Police still confident Gino was  to blame -Page 97 Clarry â€Å"Why the change of face, eh? After promotion?† Lukie: â€Å"I’m happy. (Pause.) But i got a boss with ambitions.† Clarry talking to Lukie about Momma going to inquest; â€Å"She remembers, she forgets; what the hell difference will it make?† Knows whatever happens Gino will be declared guilty of drunken violence 3. A societies attitudes towards a minority race can be changed when they gain a greater understanding of the people aligned with that race rather than basing their judgment on stereotypes – Reflects upon the belief that racism is taught rather than inherited or ‘natural’ – Clarry represents this thesis, connotations of the title refer to him -Represented as a typical Aussie bloke, ie â€Å"could obviously manage without help in a fight,† page 20. In reference to Barry, the scrap metal collector who pushes in line in front of Gino, Clarry reasons that â€Å"Because he’s an older man, that’s why. He was in this game before you were even in this country.† â€Å"Rugged man of 36,† page 20 – Start of the novel Clarry loves Maria but doesn’t want to be acknowledged as being related to Bianchi’s. Maria: ‘†¦when he’s introduced Gino to people, but never once did he call him his brother-in-la w† page 77 He isn’t violent but he still has aspects of racism Refer to conversation with Lukie about Gino being guilty, he sticks up for them Challenges authority figures and calls their kid Gino â€Å"But last night-it clicked for me. I dunno†¦ I felt sort of†¦ good†¦Ã¢â‚¬  stereotype emotion, shows side 4. Alcohol is needed to have a good time and celebrate (Clarry and Donny) and the violence etc from it (misusing alcohol) -Donny Pratt: Represents alcoholism in Australia. (Leila bursts from the house with a ottle of beer and glasses†¦) â€Å"Here: quick, to wet its head. â€Å"Clarry (And he wrenches the top from a bottle.) â€Å"Here, Pop, grab yourself a lifeboat and hop inta that,† page 48. Reference to getting drunk, part of Aussie lifestyle. He is working class. Expresses the overlooking of domestic violence at the time. â€Å"How can I a hit you if I don’t remember?† Page 88 – Naturalised violence.

The Holocaust and The Final Solution Essay - 645 Words

The Holocaust was not just bad; it was horrific in every way. The Final Solution was meant to control people and scare people. Over eleven million people died in Europe. The United States came in later than they should have, but they stopped the Axis Powers from gaining too much control. However, my people, the Jewish people, would never forget the tragedy that doomed millions of lives. It was all started by a man named Adolf Hitler. Native to Austria, he fought for Germany in World War One. After germany surrendered, Hitler was furious. He wanted Germany to rise to what his vision of greatness was. After a failed attempt to overthrow the government, he got into politics. A few years later, he became chancellor of Germany. Hitler then†¦show more content†¦She was in hiding for two and a half years with her sister Margot, mother and father, Peter Van Daan, his mother and father, and Albert Dussel. Then the police found them and took them to transport camp. From there, they were taken to a labor camp. They were seperated by gender and never saw each other again. Anne and Margot were taken to another camp after they got sick. Margot died a few weeks later, followed by Anne, who had survived just days before their camp was freed by the Allies. Everyone perished except for Annes father, Otto Frank. He went back to their hiding space to see if anything had been s alvaged and he saw Annes diary. In it were stories and everything that had happend while she was there. He published it in honor of Anne and died many years later. In Washington D.C, President Franklin Delano Roosevelt was planning out attcaks on the Axis Powers, getting advice and suggestions from the generals. Early on, the United States wanted nothing to do with World War Two. Japan took that as a threat and bombed Pearl Harbor on December 7th, 1941. This caused the US to declare war on the Axis Powers The Axis Powers were Italy, Germany, and Japan. 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