Unified Power Quality Conditioner Engineering Essay

Unified Power Quality Conditioner Engineering Essay Abstract-The aim of this paper is to present a constant frequency unified power quality conditioning system(CFUPQC)which consists of an unified power quality conditioner(UPQC) extended by adding a frequency changer in between the shunt active filter and series active filter . The series active filter and shunt active filters mainly used to compensate the voltage, current imbalance and harmonics. The frequency converter is used to compensate the supply frequency when it varies beyond the power quality limit. The proposed configuration all converters are connected back to back on the dc side and share the common dc link capacitor. The simulation results are presented to confirm that the new approach has better performance than the traditional UPQC. Index Terms-CFUPQC, frequency changer, voltage source converter (VSC), Matlab simulink INTRODUCTION Uunifed power quality conditioner is an advanced concepts in the area of power quality control. The basic working principle of unified power quality conditioner is based on series and parallel power converters that share a common dc link [1].Unified power quality conditioner is used to compensate voltage sag, voltage swell [2] , current harmonics [3] it is also creates an impact on the reactive power [4] through shunt voltage source inverter and series voltage source inverter. In order to avoid the switching oscillation, a passive filter is applied at the output of each inverter. At the output of shunt inverter a high pass second order LC filter is allocated and the output of series inverter low pass second order LC resonance filter is allocated. UPQC controller provides the compensation voltage through the UPQC series inverter and conditioning the current through the shunt inverter by instantaneous sampling of load current and source voltage. The reference current are compared with the shunt inverter output current (,) and are fed to hysteresis type (PWM) current controller. There are some problems with PQC. As the supply frequency changes the UPQC will not compensate the voltage sag and swell and current harmonics properly. This happens due to the presence of LC filters at the Inverters output terminals. It is directly affected by the variation of supply frequency. Fig.1: Basic Configuration of Constant Frequency Unified Power Quality Conditioner (CFUPQC) Fig 1 shows the proposed improved configuration of constant Frequency unified power quality conditioner. This modified unified power quality conditioner concepts enables the PWM converter to perform not only active filtering purpose, also the function of frequency changer. The compensation principle of the CFUPQC will be described in the coming sections. The proposed unified power quality conditioner has to satisfy the following requirements. Reactive power is maintained at minimum value. The load voltage should be maintained at the rated supply voltage. Maintain the input current with very low harmonic content. Assure the supply frequency is permissible within the power quality limits .The simulations result will be presented to validate the proposed CFUPQC. frequency quality indices In order to characterize the power system frequency under normal operating condition the following indices are used Where fr is the rated frequency (50 or 60) Hz and f is the real frequency. The relative frequency deviation (2) The integral deviation during the delay required to ensure appropriate of clock synchronized to the electrical network frequency (3) According to the standard En 50160/2006rated frequency of supply voltage is 50Hz.Under normal operation conduction the mean value of the fundamental frequency measured over loss stay within the following range. 50 Hz+ 1%.ie 49.5-50.5Hz for 99.5%of the year 50 Hz+ 4%.ie 47-52Hz for 100%of the time. But as power frequency may not be exactly 50Hz within the time interval. The fundamental frequency output is the ratio of the number of integer cycle counted clearing 10s time interval divided by the cumulative value of the integer value. The step taken to maintain the frequency with in required limits render deviation from the normalized value very rate phenomena. In this way an analysis is of the influence of frequency variation on the final customer is only for a reduced interval about +3Hz of the rated value and for rather short period. Within the reduced variation field (40%)a considerable number of static customers are not affected by the system variation(rectifier , resistance, ovens, electric arc ect)but 60%of the consumers (fans, motors ect)affected by the frequency variations. The asynchronous and synchronous driving motors connected the supply network used extensely in individual acceleration have the power frequency changes. Depending on the mechanical characteristic spee d of the motor and also depends on the supply frequency [13].The speed of asynchronous motors or synchronous motor unlimited drags to the electric power supply variations s proportional to the applied voltage frequency. The frequency variation leads to the correspond modification of the process production time throughout the supply with a reduced frequency depressing the supply frequency capacitive circuit, transformer, relay coil are affected Constant Frequency Unified Power Quality Conditioner (CFUPQC) CFUPQC structure Fig.3: Proposed Configuration Modified configuration of UPQC consist of shunt active filter, series active filter, voltage source inverter and voltage source converter shown in Fig(3).CFUPQC similar to the UPQC expect the frequency changing section. UPQC has the potential drawbacks in the hybrid filtering performance. Since its filter in characteristics depends on load impedance and supply frequency. CFUPQC series active filter is used for compensation the voltage harmonics and voltage imbalance In addition the voltage source converter supplies the AC to DC power and is fed to common DC link. The CFUPQC consists of parallel active filter (PAF) that eliminates load harmonics and compensates load reactive power. The control equation is Ipf=G.IL (4) Where g is the control function, is fundamental frequency.IL is the load current, Ipf is the parallel filter input current components for compensation are extracted from load current and load voltages using theory while the converter is a current controlled device using 20 kHz clocked hysteresis band. Series active filter (SAF) that compensates supply harmonics flicker, voltage sag/swell, unbalance and diode + capacitor type load harmonics to flow in to the parallel filter. Control equation is comp (5) Where k is regulator gain, Usf is the series filter voltage, Ish are harmonic supply current and Ucomp is compensation voltage needed to remove supply voltage imperfection. Ish are extracted to theory. Active rectifier (AR) for real power transfer to/from common DC bus and for DC bus control. Switching losses and power received from the dc link capacitors through the series inverter can decrease the average value of dc bus. Other distortions such as unbalanced conditions and sudden changes in load current can result in oscillation in dc bus voltage .In order to solve the fluctuated dc voltage the three phase rectifier is used .DC bus voltage is maintained constant using three-phase rectifier converter for bi-directional power flow and is controlled in such a way that it is insensitive to supply voltage imperfections. Rms value of the output voltage Vorms=0.9558Vml Rms value of the output current Iorms=0.9558Iml Where ml is maximum value of line current. Multi stage 48 pulse voltage source inverter (VSI) supplies the constant power frequency when the supply frequency will change. Here multilevel voltage source inverter is used, to eliminate the harmonic component of the output. The frequency converter is placed in between the series and shunt active filters. Normally the voltage source converters (rectifiers) generate the current harmonics. In order to avoid the harmonics and reactive power the rectifier is placed at the middle of the two active filters. Similarly if the load is increased voltage dip may occur in front of voltage source inverter. At the same time series active filter compensate the voltage problems. Control system of the CFUPQC shunt Part Fig.4: Control System of the Shunt CFUPQC 1) CFUPQC shunt inverter control system: In the Fig (4) shows the shunt inverter controlling block diagram of CFUPQC using synchronous reference frame theory where the sensitive loads current are . The measured currents of load are transferred in to frame using sinusoidal functions through synchronous reference frame conversion. The sinusoidal functions are obtained through the grid voltage using phase lock loop(PLL). Here the currents are divided in to ac and dc components (6) (7) The equation (6) and (7) and are the real and reactive components.ac components and dc elements can be derived by low pass filter.are the dc components and are the ac components of . The control algorithm corrects the systems power factor and compensates all the current harmonica component by generating the reference currents given in equation = (8) = (9) The reference current is transferred in to frame through reverse conversion of synchronous reference frame. Resulted reference current () and the output current of shunt inverter () are fed to the hysteresis band controller. Now the required controlling pulses are generated and the required compensation current is generated by the inverter applying these signals to shunt inverters power switch gates. 2) CFUPQC Series Inverter Control System Fig.5: Control System of the Series CFUPQC 2) CFUPQC series inverter control system: Fig (5) shows the CFUPQC series inverter controlling block diagram using synchronous reference frame theory. In this method the desired value of load phase voltages in d axis and q axis is compared with the load voltage and the result is consider as the reference signal. The supply voltage detected is detected and transformed in to the synchronous reference frame using (10) The compensating reference voltage in the synchronous reference frame is defined as (11) The compensating reference voltage in (11) is then transformed back into the reference frame .Resulted reference voltage () and the output current of shunt inverter () are fed to the hysteresis band controller. The required controlling pulses are generated and the required compensation voltage is generated. 3) Control system of 48 pulse voltage source inverter: 48-pulse voltage source converter consists of four three phase, 3-level inverters and 4 phase-shifting transformers creating phase shift of +/- 7.5 °degree. This transformer setup neutralizes all odd harmonics up to 45th harmonic. Eight 6-pulse inverters are combined to obtain a 48-pulse with the purpose of reducing harmonic content. Table 1 shows the values of phase shifts which are applied to the inverter voltages in two steps, namely in firing pulses and in Zig-zag transformers, to create a 48-pulse waveform at the output . Table 1:48 Pulse voltage source Inverter Coupling transformer Gate pulse pattern Phase shifting transfer Y-Y +11.25 ° -11.25 ° Δ-Y -18.75o -11.25o Y-Y -3.75o +3.75o Δ-Y -33.75o +3.75o Y-Y +3.75o -3.75o Δ-Y -26.25o -3.75o Y-Y -11.25o +11.25o Δ-Y -41.25o +11.25o content in the order of n= 48m ±1, where m= 0, 1, 2. The main-inverter intermediate-circuit capacitors together have an energy storage capacity of only 15 J/kVA. An output switching frequency of 1 kHz is chosen, which is fairly reasonable for this converter. Input is a frequency reference, which is passed through a rate limiter in order to be within the limits of maximum acceleration. Fig.6: Control System of the Frequency changer CFUPQC Except for the 23rd and 25th harmonics, this transformer arrangement neutralizes all odd harmonics up to 45th harmonic. Y and D transformer secondarys cancel harmonics 7+12n (7, 19, 31, 43,)and 5+12n (5, 17, 29, 41,) .In addition, the 15 ° phase shift between the two groups (Tr1Y and Tr1D leading by 7.5 °, Tr2Y and Tr2D lagging by 7.5 °) that allows cancellation of harmonics 11+24n (11, 35,) and 13+24n (13, 37,). Considering that all 3n harmonics are not transmitted by the transformers, the first harmonics that are not canceled by the transformers are therefore the 23rd, 25th, 47th and 49th harmonics. By choosing the appropriate conduction angle for the three-level inverter (ÏÆ' = 172.5 °), the 23rd and 25th harmonics can be minimized. Using a bipolar DC voltage, the voltage source inverter thus generates a 48-step voltage approximatly a sine wave. The secondary sides of the coupling transformers are connected in series to sum the output voltages of individual VSIs and resul ts in a multi-pulse phase voltage which can be expressed mathematically as follow (12) Both equations (12) and (13) which are phase-to-phase and phase-to-neutral voltage representations, respectively, show that harmonics up to 47th order are inherently filtered. The signalization of the 48-pulse inverter are generated for the inverter having -41.25 of gate pulse phase and directly fed to the corresponding inverter. PWM signals for the remaining inverters are obtained by applying relevant phase shifts to the set of PWM signals generated. For example, in order to obtain the pulses for the inverter having -11.25o of gate pulse +30o of phase shift is applied to the closed loop current controllers output. In practice, the phase shifting of the pulses is realized by applying a delay in the first cycle. The generated set of pulses is the earliest set appearing at the time-line and since it is not possible to apply a negative delay the earliest appearing set is generated and the rest are delayed accordingly. When the supply frequency is exceeded beyond the power quality limit the constant frequency voltage source inverter control system change the load from source power supply to the constant frequency inverter power supply. Simulation Results The proposed system, simulation results is simulated by MATLAB software. Fig 7Current harmonic minimization when the supply frequency is normal In the above simulation some capabilities of UPQC to solve power quality problems are shown. The nonlinear load which is produced harmonic current to the network. Fig. 7 shows that the shunt part of UPQC compensates these harmonics Components when the supply frequency is normal. Now assume that a deep and unbalance voltage sag, as occurs at t = 0.2 s to 0.25 s and voltage swell occurred 0.26 and lasts for 0.3 second. Fig.8. Sag swell condition when the supply frequency is normal In Fig(8) the UPQC inject the compensation voltage via series inverter and compensate efficiently at 0.2 second sag condition and voltage swell condition at supply frequency normal (60Hz) Fig .9.Series UPQC when the frequency exceed the power quality limit In fig 9 shows the operation of UPQC when the supply frequency exceeds the power quality limits the output was not found satisfactory .The supply beyond the power quality limit (greater than 63 Hz)at 0.25 second the load voltage waveform varies. The frequency increase rapidly the voltage waveform highly distorted as shown in the simulation results Fig 9. Based on the simulation result Fig 10 it is intended that if the supply frequency varies greater than power quality limit the load current wave form is distorted. If the frequency increases the wave form also distort rapidly as shown in fig10. Fig 10. CF- UPQC Operated when Frequency greater than the Power quality limits Fig 11. CF- UPQC Operated when Frequency greater than the Power quality limits Fig 11showsthe proposed CFUPQC model was simulated for a period of 0.01 sec to 0.5 sec from the results in fig 11, it was seen that at 0.28 sec the supply frequency crossed the power quality limit at 0.29. Fig.12. CF-UPQCs inverter supplying current under over frequency condition The above simulation shows the 48 pulse inverter carries the load current when the supply frequency varied beyond the power quality limit. When the frequency exceed the limits at 0.28 sec. the voltage source converter supply the power. The above simulation result Fig(13) clearly shows when the frequency changes the asynchronous motor speed also changes and the UPQC also not deliver the voltage sinusoidal. In this case the load connected in to paper mills, relays are affected. Fig.13. UPQC connected asynchronous motor under over frequency condition Fig.14. CFUPQC connected asynchronous motor under over frequency condition The proposed model simulation fig 14 shows when the supply frequency change the motor speed not changed and the CFUPQC also work satisfactory TABLE I11 PARAMETER VALUES OF THE UNDERPROPOSED SYSTEM Power quality problems UPQC UPQC CF-UPQC CF-UPQC Frequency Hz 58-62Hz >62Hz-60-

Benito Mussolini: A Destined Failure Essay -- Italian History, Politic

Absolute power and influence, is and has always been something extremely difficult to obtain, and as we have seen throughout the course of history such authority and control left in the hands of a single person can quickly crumble at their very feet. As with most, this often happens in part by self-destructive means. Case and point, Benito Mussolini, a man who at one point held total power over the entire Italian population; seemingly overnight he lost all control and eventually found himself hanging from the end of a meat hook. Now knowing just who he was as a person, what actions he took, and the decisions he made, some might argue that his reign in the end was preordained for catastrophe. Myself, I would tend to agree with this statement. Nevertheless, let us take a few steps back and revisit the periods of Mussolini’s life leading up to his ultimate demise. The stages of his life in which he was influenced by loved ones and strangers alike. In essence, the moments in time that sculpted the intellect, opinions, beliefs, even ideologies of the man who was. Starting from the beginning and working forward, I want to dissect Mussolini in a way that helps us understand why and how he was shaped into the person he became. How was Mussolini influenced by his father and mother? What drove Mussolini to eventually create and promote Fascism as we know it? Then, with a freshly painted portrait of the man we knew as â€Å"Il Duce†, we can pinpoint the flaws of his being to see what went wrong in, or rather how Mussolini went about, implementing the fascist idea incorrectly. Moreover, with these questions in mind we can evaluate my perceived notion that Mussolini was simply destined for failure. Benito Mussolini was born the son of a blacksmit... ...ists) (Gregor 95). This was the first step of many that would take Mussolini’s small, organized group of followers and himself to their futures as ruling fascists. Once more Mussolini completely reinvented himself and his ideology in the years to come. On March 23, 1919, Mussolini founded the Fasci Italiani di Combattimento, welcoming civilians and veterans alike in the fight for Fascism (Hoyt 113). Fascism in its’ early state spread under the values of nationalism and unity, despite ones class. However, Mussolini’s idea of fascism was not what it turned out to be. He took philosophies and ideologies alike and blended them to his approval. Mussolini’s fascism opposed democratic rule, protected the class system, rejected egalitarianism, encouraged militarization, and demanded civic duties for the states wellbeing; fascism was action and with action came results.

Relationship Between Private and Public Police

Relationship between Private and Public Police G00fydad CJS/250 March 10, 2013 John Doe Relationship between Private and Public Police The police in our society carry with them a deep sense of tradition and honor that stems from generations of serving and protecting the public. This pride can, at times, lead some police to believe that they are the last line of defense with the public they serve and any other entity that appears to be encroaching on that territory should be mistrusted.This attitude does not mix well with others attempting to perform the same job function such as private security. Thankfully this is not the consensus of all public police officers. Most public police understand that they require the assistance of the private sector and will welcome the help where it is offered. The public police also understand that that private security entities are often times the first to respond at many of the incidents that later involve the public police.It has been estimated tha t nearly 85 percent of the country’s critical infrastructure is protected by private security (Ohlhausen, 2004). When the private security firms handle such a large majority of the policing duties it is essential that the relationship between the private and public police forces relate well to one another and cooperate whenever possible. One of the largest issues with the relationship between the public and private police stems from the general population’s opinion.The public police are looked upon as the legitimate police force and the private security departments are looked upon with very little respect by the community at large. This can be seen at most shopping malls when someone is committing a crime. When the security officer intervenes that situation may only deescalate slightly and the participants still look upon the security officer with little respect. However, when a public police officer arrives the situation is typically handled swiftly and all parties in volved take things far more serious.This image of private security officers and the relationship they hold with the public police is often exacerbated by the media in television and movies. They portray the security officers as lazy, bumbling, and not very smart. Of course these are the media’s vision of private security, but this is the general public consensus about the private security firms. This attitude and lack clear role definition of the private security field is a major roadblock in path of cooperation between the public and private sectors.According to a report issued by the Private Security Advisory Council, the Law Enforcement Assistance Administration, and the U. S. Department Of Justice the major causes for the role conflict problems is a lack of mutual respect, lack of communication, lack of cooperation, lack of law enforcement’s knowledge of private security, perceived competition, lack of standards, and perceived corruption (1977). This separation of the public and private police is becoming less noticeable these days thanks to the education of both sides.The public and private police understand that they require the help and cooperation of each other. For example, with regard to public and private space, the public police must have probable cause or a warrant issued by a judge in order to search a location. The private security officer does not require any such warrant. The private security officer only needs to conduct the search within the confines of his or her allowable space, or the area in which they normally operate.For instance, a public police officer may not be allowed to come into an office building and search the office for narcotics without a warrant, but the company’s security officer is fully allowed to search the premises and turn over any evidence found. This definition between public and private space can be an advantage to public police. However, if the private security does not feel obliged to coopera te then the public police will need to work through other, longer, channels to get their job completed.This can happen if the private security feels that they would rather handle an incident of criminal activity internally and will not allow the public police to intervene in the process. The private security entities make this decision from time to time for a variety of reasons including the mistrust of the court system to fully sanction the offender and the feeling that the current court system is a â€Å"revolving door† situation. It is situations such as these that prevent our public police and private security from having a truly unifying system.According to Boston Massachusetts Transit Police Chief Joseph C. Carter, since September 11, 2001 law enforcement agencies have been under tremendous pressure to conduct their traditional crime prevention and response activities and perform an immense amount of homeland security work, in a time of tight city, county, tribal, and s tate budgets (2007). In a time of financial crisis for all areas of the government we must rely on the private security development and ensure that the public police and the private security entities work together to keep things safe.In order for the public police and private security to truly work together government rules and regulations need to be enacted and the private sector would have to fall under the umbrella of government oversight. The private security entities would have to answer for the actions they take, and they would have to adhere to the same rules and regulations as public police. However, if this were to happen then the entire rules of search and seizure would have to change as well as many other law enforcement policies.Once this change takes place within the government the public and private police will be able to interact with little interference and issue making the ability to deal with crimes far easier. This will have the added benefit of improving not only the image of private security in the community’s eyes, but also the relationship between public and private police agencies. While the relationship between the public and private police agencies can be strained at times, and relaxed at others the cooperation between both is very important and should be encouraged by all involved.The public image of private security must also change and the officers within the realm of private security should be afforded the same respect and courtesy that public police already experience. This new attitude by the general populace coupled with government involvement and support will only serve to improve the relationship between public and private police. References Ohlhausen, P. (2004). In T Seamon (Chair). Building private security/public policing partnerships to prevent and respond to terrorism and public disorder. National policy summit.Retrieved from http://cops. usdoj. gov/files/RIC/Publications/national_policy_summit. pdf Bilek, A. (197 7, June). In A. Bilek (Chair). Law enforcement and private security sources and areas of conflict and strategies for conflict resolution. Retrieved from https://www. ncjrs. gov/pdffiles1/Digitization/44783NCJRS. pdf Carter, J. (2007). Public-private partnerships: Vital resources for law enforcement. Retrieved from http://www. policechiefmagazine. org/magazine/index. cfm? fuseaction=display_arch&article_id=1257&issue_id=92007

How to Trace American Indian Roots in Your Ancestry

Whether you want to become an enrolled member of a federally recognized tribe, verify a family tradition that you descended from an American Indian, or just want to learn more about your roots, researching your Native American family tree beings just like any other genealogy research - with yourself. Start Your Climb Up the Family Tree Unless you have a large collection of facts on your Indian ancestor, including names, dates, and tribe, it is usually not helpful to begin your search in Indian records. Learn everything that you can about your parents, grandparents, and more distant ancestors, including ancestral names; dates of birth, marriages, and death; and the places where your ancestors were born, married, and died. You can start by constructing your family tree. Track Down the Tribe During the initial phase of your research, the goal, especially for tribal membership purposes, is to establish and document the relationships of Indian ancestors and to identify the Indian tribe with which your ancestor may have been affiliated. If youre having trouble finding clues to your ancestors tribal affiliation, study the localities in which your Indian ancestors were born and lived. Comparing this with Indian tribes that historically resided in or currently live in those geographical areas may help you to narrow down the tribal possibilities. The Tribal Leaders Directory published by the U.S. Bureau of Indian Affairs lists all 566 federally recognized American Indian Tribes and Alaska Natives in a PDF document. Alternatively, you can access this same information through an easy-to-browse database of Federal and State Recognized American Indian Tribes, from the National Conference of State Legislators. John R. Swantons, The Indian Tribes of North America, is another excellen t source of information on more than 600 tribes, sub-tribes, and bands. Learn Background on Each Tribe Once youve narrowed your search to a tribe or tribes, it is time to do some reading on tribal history. This will not only help you understand the traditions and culture of the tribe in question but also evaluate your family stories and legends against historical facts. More general information on the history of Native American tribes can be found online, while more in-depth tribal histories have been published in book form. For the most historically accurate works, look for tribal histories published by University Press. Research Using the National Archives Once youve identified the tribal affiliation of your Native American ancestors, it is time to begin research in records about American Indians. Because the U.S. federal government interacted frequently with the Native American tribes and nations during the settlement of the United States, many useful records are available in repositories such as the National Archives. The Native American collection at the National Archives includes many of the records created by branches of the Bureau of Indian Affairs, including annual tribal census rolls, lists relating to Indian removal, school records, estate records, and claims and allotment records. Any American Indian who fought with federal troops may have a record of veterans benefits or bounty land. For more information on the specific records held by the National Archives, visit their Native American Genealogy guide or check out Guide to Records in the National Archives of the United States Relating to American Indians, compiled by archivi st Edward E. Hill. If you want to do your research in person, most of the main tribal records are stored at the National Archives Southwest Region in Fort Worth, Texas. Even more accessible, some of the most popular of these records have been digitized by NARA and placed online for easy searching and viewing in the National Archives Catalog. Online Native American records at NARA include: Index to the Final (Dawes) Rolls of the Five Civilized TribesIndex to Applications Submitted for the Eastern Cherokee Roll of 1909 (Guion-Miller Roll)Wallace Roll of Cherokee Freedmen in Indian Territory, 1890Kern-Clifton Roll of Cherokee Freedmen, January 16, 18671896 Citizenship Applications Bureau of Indian Affairs If your ancestors had land in trust or went through probate, the BIA field offices in selected areas throughout the United States may have some records concerning Indian ancestry. However, the BIA field offices do not maintain current or historical records of all individuals who possess some degree of Indian blood. The records the BIA holds are current rather than historic tribal membership enrollment lists. These lists (commonly called rolls) do not have supporting documentation (such as birth certificates) for each tribal member listed. The BIA created these rolls while the BIA maintained tribal membership rolls.