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124-513: HVDC Kingsnorth was a high-voltage direct-current ( HVDC ) transmission system connecting Kingsnorth in Kent to two sites in London . It was at one time the only application of the technology of high voltage direct current transmission for the supply of transformer stations in a city, and the first HVDC link to be embedded within an AC system, rather than interconnecting two asynchronous systems. It
248-613: A Portuguese colony until 1808, when the capital of the empire was transferred from Lisbon to Rio de Janeiro . In 1815, the colony was elevated to the rank of kingdom upon the formation of the United Kingdom of Portugal, Brazil and the Algarves . Independence was achieved in 1822 with the creation of the Empire of Brazil , a unitary state governed under a constitutional monarchy and a parliamentary system . The ratification of
372-617: A colony . In 1815, to justify continuing to live in Brazil, where the royal court had thrived for six years, the Crown established the United Kingdom of Portugal, Brazil and the Algarves , thus creating a pluricontinental transatlantic monarchic state. However, the leadership in Portugal, resentful of the new status of its larger colony, continued to demand the return of the court to Lisbon (see Liberal Revolution of 1820 ). In 1821, acceding to
496-489: A democratic federal republic . Due to its rich culture and history, the country ranks thirteenth in the world by number of UNESCO World Heritage Sites . Brazil is a regional and middle power that is an emerging power and a major non-NATO ally of the United States . Categorized as a developing country , Brazil is considered an advanced emerging economy , having the one of the-largest GDP in
620-497: A vector product , decreases. Since DC power has no phase, the phase shift cannot occur in the DC case. HVDC transmission may also be selected for other technical benefits. HVDC can transfer power between separate AC networks. HVDC power flow between separate AC systems can be automatically controlled to support either network during transient conditions, but without the risk that a major power-system collapse in one network will lead to
744-554: A 12 kV DC transmission line, which also served to convert 40 Hz generation to serve 60 Hz loads, at Mechanicville, New York . In 1941, a 60 MW, ±200 kV, 115 km (71 mi) buried cable link, known as the Elbe-Project , was designed for the city of Berlin using mercury arc valves but, owing to the collapse of the German government in 1945 , the project was never completed. The nominal justification for
868-872: A charismatic figure who could represent a moderate face of power, during this period a series of localized rebellions took place, such as the Cabanagem in Grão-Pará , the Malê Revolt in Salvador, the Balaiada ( Maranhão ), the Sabinada ( Bahia ), and the Ragamuffin War , which began in Rio Grande do Sul and was supported by Giuseppe Garibaldi . These emerged from the provinces' dissatisfaction with
992-452: A circuit that is effectively an ultra-high-voltage motor drive. More recent installations, including HVDC PLUS and HVDC MaxSine, are based on variants of a converter called a Modular Multilevel Converter (MMC). Multilevel converters have the advantage that they allow harmonic filtering equipment to be reduced or eliminated altogether. By way of comparison, AC harmonic filters of typical line-commutated converter stations cover nearly half of
1116-452: A collapse in the second. The controllability feature is also useful where control of energy trading is needed. Specific applications where HVDC transmission technology provides benefits include: Long undersea or underground high-voltage cables have a high electrical capacitance compared with overhead transmission lines since the live conductors within the cable are surrounded by a relatively thin layer of insulation (the dielectric ), and
1240-431: A colony. The Brazilians refused to yield, and Prince Pedro decided to stand with them, declaring the country's independence from Portugal on 7 September 1822. A month later, Prince Pedro was declared the first Emperor of Brazil , with the royal title of Dom Pedro I , resulting in the founding of the Empire of Brazil . The Brazilian War of Independence , which had already begun along this process, spread through
1364-837: A dense and complex system of rivers, one of the world's most extensive, with eight major drainage basins, all of which drain into the Atlantic. Major rivers include the Amazon (the world's second-longest river and the largest in terms of volume of water), the Paraná and its major tributary the Iguaçu (which includes the Iguazu Falls ), the Negro , São Francisco , Xingu , Madeira and Tapajós rivers. The wildlife of Brazil comprises all naturally occurring animals , plants , and fungi in
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#17328007318761488-410: A distance of 200 kilometres (120 mi), including 10 kilometres (6.2 mi) of underground cable. This system used eight series-connected generators with dual commutators for a total voltage of 150 kV between the positive and negative poles, and operated from c. 1906 until 1936. Fifteen Thury systems were in operation by 1913. Other Thury systems operating at up to 100 kV DC worked into
1612-504: A full dictatorship with the promulgation of the Fifth Institutional Act in 1968. Oppression was not limited to those who resorted to guerrilla tactics to fight the regime, but also reached institutional opponents, artists, journalists and other members of civil society, inside and outside the country through the infamous " Operation Condor ". Like other brutal authoritarian regimes , due to an economic boom, known as
1736-468: A given transmission line to operate with a constant HVDC voltage that is approximately the same as the peak AC voltage for which it is designed and insulated. The power delivered in an AC system is defined by the root mean square (RMS) of an AC voltage, but RMS is only about 71% of the peak voltage. Therefore, if the HVDC line can operate continuously with an HVDC voltage that is the same as the peak voltage of
1860-446: A high resistance when conducting, wasting energy and generating heat in normal operation. The ABB breaker combines semiconductor and mechanical breakers to produce a hybrid breaker with both a fast break time and a low resistance in normal operation. Generally, vendors of HVDC systems, such as GE Vernova , Siemens and ABB , do not specify pricing details of particular projects; such costs are typically proprietary information between
1984-427: A higher altitude. In the interior northeast, seasonal rainfall is even more extreme. South of Bahia, near the coasts, and more southerly most of the state of São Paulo, the distribution of rainfall changes, with rain falling throughout the year. The south enjoys subtropical conditions, with cool winters and average annual temperatures not exceeding 18 °C (64.4 °F); winter frosts and snowfall are not rare in
2108-399: A maximum power of 640 megawatts (320 megawatts per pole). In 1981, one mercury arc valve at Willesden Static Inverter Plant, was replaced by a H200 thyristor valve, developed by English Electric. The system described was shut down in 1986 or 1987 following system reinforcement on the network it was embedded in. However the capacitor banks located at Kingsorth were used for voltage control on
2232-460: A metal sheath. The geometry is that of a long coaxial capacitor . The total capacitance increases with the length of the cable. This capacitance is in a parallel circuit with the load. Where alternating current is used for cable transmission, additional current must flow in the cable to charge this cable capacitance. Another way to look at this is to realize, that such capacitance causes a phase shift between voltage and current, and thus decrease of
2356-523: A military one , did civilians take power, remaining there until October 1930. In relation to its foreign policy, the country in this first republican period maintained a relative balance characterized by a success in resolving border disputes with neighboring countries, only broken by the Acre War (1899–1902) and its involvement in World War I (1914–1918), followed by a failed attempt to exert
2480-405: A much lesser extent. Nevertheless, for a long AC overhead transmission line, the current flowing just to charge the line capacitance can be significant, and this reduces the capability of the line to carry useful current to the load at the remote end. Another factor that reduces the useful current-carrying ability of AC lines is the skin effect , which causes a nonuniform distribution of current over
2604-420: A number of oceanic archipelagos , such as Fernando de Noronha , Rocas Atoll , Saint Peter and Paul Rocks , and Trindade and Martim Vaz . Its size, relief, climate, and natural resources make Brazil geographically diverse. Including its Atlantic islands, Brazil lies between latitudes 6°N and 34°S , and longitudes 28° and 74°W . Brazil is the fifth largest country in the world, and third largest in
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#17328007318762728-410: A political crisis, after having returned to power by election in 1950. Several brief interim governments followed Vargas's suicide. Juscelino Kubitschek became president in 1956 and assumed a conciliatory posture towards the political opposition that allowed him to govern without major crises. The economy and industrial sector grew remarkably, but his greatest achievement was the construction of
2852-530: A prominent role in the League of Nations ; Internally, from the crisis of Encilhamento and the Navy Revolts , a prolonged cycle of financial, political and social instability began until the 1920s, keeping the country besieged by various rebellions, both civilian and military. Little by little, a cycle of general instability sparked by these crises undermined the regime to such an extent that in
2976-482: A result of a civil war in Mozambique . The transmission voltage of ±533 kV was the highest in the world at the time. Line-commutated converters have some limitations in their use for HVDC systems. This results from requiring a period of reverse voltage to affect the turn off. An attempt to address these limitations is the capacitor-commutated converter (CCC). The CCC has series capacitors inserted into
3100-401: A similar concept HVDC PLUS ( Power Link Universal System ) and Alstom call their product based upon this technology HVDC MaxSine . They have extended the use of HVDC down to blocks as small as a few tens of megawatts and overhead lines as short as a few dozen kilometers. There are several different variants of VSC technology: most installations built until 2012 use pulse-width modulation in
3224-413: A three-phase bridge rectifier known as a six-pulse bridge , containing six electronic switches, each connecting one of the three phases to one of the two DC rails. A complete switching element is usually referred to as a valve , irrespective of its construction. However, with a phase change only every 60°, considerable harmonic distortion is produced at both the DC and AC terminals when this arrangement
3348-454: A valve becoming positive (at which point the valve would start to conduct if it were made from diodes) and the thyristors being turned on. The DC output voltage of the converter steadily becomes less positive as the firing angle is increased: firing angles of up to 90° correspond to rectification and result in positive DC voltages, while firing angles above 90° correspond to inversion and result in negative DC voltages. The practical upper limit for
3472-653: A voltage of +266 kV terminated at the converter station in Beddington near Croydon . The negative pole continued to run a further 26 kilometers at -266 kV line to a similar station at Willesden in North London. There was also the possibility, if the converter station in Kingsnorth was out of service, to run the system as monopolar HVDC between the Beddington and Willesden stations. The HVDC Kingsnorth
3596-462: A wider power transmission grid to another. Changes in load that would cause portions of an AC network to become unsynchronized and to separate, would not similarly affect a DC link, and the power flow through the DC link would tend to stabilize the AC network. The magnitude and direction of power flow through a DC link can be directly controlled and changed as needed to support the AC networks at either end of
3720-527: Is Brasília , and its most populous city is São Paulo . Brazil is a federation composed of 26 states and a Federal District . It is the only country in the Americas where Portuguese is an official language . Brazil is among the world's most multicultural and ethnically diverse nations, due to over a century of mass immigration from around the world . Bounded by the Atlantic Ocean on
3844-521: Is a folk etymology for a word for the plant related to an Arabic or Asian word for a red plant. As brazilwood produces a deep red dye, it was highly valued by the European textile industry and was the earliest commercially exploited product from Brazil. Throughout the 16th century, massive amounts of brazilwood were harvested by indigenous peoples (mostly Tupi ) along the Brazilian coast, who sold
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3968-440: Is also known as line-commutated converter (LCC) HVDC. On March 15, 1979, a 1920 MW thyristor based direct current connection between Cabora Bassa and Johannesburg (1,410 km; 880 mi) was energized. The conversion equipment was built in 1974 by Allgemeine Elektricitäts-Gesellschaft AG (AEG) , and Brown, Boveri & Cie (BBC) and Siemens were partners in the project. Service interruptions of several years were
4092-490: Is also the subject of significant global interest, as environmental degradation (through processes such as deforestation ) has direct impacts on global issues such as climate change and biodiversity loss . The territory of present-day Brazil was inhabited by numerous tribal nations prior to the landing of explorer Pedro Álvares Cabral in 1500. Subsequently claimed by the Portuguese Empire , Brazil remained
4216-475: Is complex (especially with line commutated converters), as is expanding existing schemes to multi-terminal systems. Controlling power flow in a multi-terminal DC system requires good communication between all the terminals; power flow must be actively regulated by the converter control system instead of relying on the inherent impedance and phase angle properties of an AC transmission line. Multi-terminal systems are therefore rare. As of 2012 only two are in service:
4340-467: Is left over from £750M for the installed works. Add another £200–300M for the other works depending on additional onshore works required. An April 2010 announcement for a 2,000 MW, 64 km (40 mi) line between Spain and France is estimated at €700 million. This includes the cost of a tunnel through the Pyrenees. At the heart of an HVDC converter station , the equipment that performs
4464-625: Is no potential difference. DC will never cross zero volts and never self-extinguish, so arc distance and duration is far greater with DC than the same voltage AC. This means some mechanism must be included in the circuit breaker to force current to zero and extinguish the arc, otherwise arcing and contact wear would be too great to allow reliable switching. In November 2012, ABB announced the first ultrafast HVDC circuit breaker. Mechanical circuit breakers are too slow for use in HVDC grids, although they have been used for years in other applications. Conversely, semiconductor breakers are fast enough but have
4588-487: Is no real dry season , but there are some variations in the period of the year when most rain falls. Temperatures average 25 °C (77 °F), with more significant temperature variation between night and day than between seasons. Over central Brazil, rainfall is more seasonal, characteristic of a savanna climate. This region is as extensive as the Amazon basin but has a very different climate as it lies farther south at
4712-531: Is referred to as the rectifier and the station that is operating with power flow from DC to AC is referred to as the inverter . Early HVDC systems used electromechanical conversion (the Thury system) but all HVDC systems built since the 1940s have used electronic converters. Electronic converters for HVDC are divided into two main categories: Most of the HVDC systems in operation today are based on line-commutated converters (LCCs). The basic LCC configuration uses
4836-542: Is used, the cable capacitance is charged only when the cable is first energized or if the voltage level changes; there is no additional current required. DC powered cables are limited only by their temperature rise and Ohm's law . Although some leakage current flows through the dielectric insulator , this effect is also present in AC systems and is small compared to the cable's rated current. The capacitive effect of long underground or undersea cables in AC transmission applications also applies to AC overhead lines, although to
4960-422: Is used. An enhancement of this arrangement uses 12 valves in a twelve-pulse bridge . The AC is split into two separate three-phase supplies before transformation. One of the sets of supplies is then configured to have a star (wye) secondary, and the other a delta secondary, establishing a 30° phase difference between the two sets of three phases. With twelve valves connecting each of the two sets of three phases to
5084-530: The Arab League . The word Brazil probably comes from the Portuguese word for brazilwood , a tree that once grew plentifully along the Brazilian coast. In Portuguese, brazilwood is called pau-brasil , with the word brasil commonly given the etymology "red like an ember ", formed from brasa ('ember') and the suffix -il (from -iculum or -ilium ). It has alternatively been suggested that this
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5208-676: The Governorate General of Brazil in the city of Salvador , which became the capital of a single and centralized Portuguese colony in South America. In the first two centuries of colonization, Indigenous and European groups lived in constant war, establishing opportunistic alliances in order to gain advantages against each other. By the mid-16th century, cane sugar had become Brazil's most important export, while slaves purchased in Sub-Saharan Africa in
5332-884: The Mantiqueira and Espinhaço mountains and the Serra do Mar . In the north, the Guiana Highlands form a major drainage divide, separating rivers that flow south into the Amazon Basin from rivers that empty into the Orinoco River system, in Venezuela, to the north. The highest point in Brazil is the Pico da Neblina at 2,994 meters (9,823 ft), and the lowest is the Atlantic Ocean. Brazil has
5456-542: The Petrobras corruption scandal . President Temer himself was also accused of corruption . According to a 2018 poll, 62% of the population said that corruption was Brazil's biggest problem. In the fiercely disputed 2018 elections , the controversial conservative candidate Jair Bolsonaro of the Social Liberal Party (PSL) was elected president, winning in the second round against Fernando Haddad , of
5580-592: The Quebec – New England Transmission between Radisson, Sandy Pond, and Nicolet and the Sardinia–;mainland Italy link which was modified in 1989 to also provide power to the island of Corsica . HVDC circuit breakers are difficult to build because of arcing : under AC, the voltage inverts and in doing so crosses zero volts dozens of times a second. An AC arc will self-extinguish at one of these zero-crossing points because there cannot be an arc where there
5704-632: The Quilombo of Palmares , and to repress all movements for autonomy or independence , such as the Minas Gerais Conspiracy . In late 1807, Spanish and Napoleonic forces threatened the security of continental Portugal , causing Prince Regent John , in the name of Queen Maria I , to move the royal court from Lisbon to Rio de Janeiro . There they established some of Brazil's first financial institutions, such as its local stock exchanges and its National Bank , additionally ending
5828-491: The South American country. Home to 60% of the Amazon rainforest , which accounts for approximately one-tenth of all species in the world, Brazil is considered to have the greatest biodiversity of any country on the planet, containing over 70% of all animal and plant species catalogued. Brazil has the most known species of plants (55,000), freshwater fish (3,000) and mammals (over 689). It also ranks third on
5952-467: The Tupi–Guarani family and fought among themselves. Though the first settlement was founded in 1532, colonization effectively began in 1534, when King John III of Portugal divided the territory into the fifteen private and autonomous captaincies . However, the decentralized and unorganized tendencies of the captaincies proved problematic, and in 1549 the Portuguese king restructured them into
6076-596: The Workers Party (PT), with the support of 55.13% of the valid votes. In the early 2020s, Brazil became one of the hardest hit countries during the COVID-19 pandemic , receiving the second-highest death toll worldwide after the United States. In May 2021, Luiz Inácio Lula da Silva stated that he would run for a third term in the 2022 Brazilian general election against Bolsonaro. In October 2022, Lula
6200-497: The first constitution in 1824 led to the formation of a bicameral legislature, now called the National Congress . Slavery was abolished in 1888. The country became a presidential republic in 1889 following a military coup d'état . An authoritarian military dictatorship emerged in 1964 and ruled until 1985, after which civilian governance resumed. Brazil's current constitution , formulated in 1988, defines it as
6324-475: The slave market of Western Africa (not only those from Portuguese allies of their colonies in Angola and Mozambique ), had become its largest import, to cope with sugarcane plantations , due to increasing international demand for Brazilian sugar. Brazil received more than 2.8 million slaves from Africa between the years 1500 and 1800. By the end of the 17th century, sugarcane exports began to decline and
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#17328007318766448-453: The " economic miracle ", the regime reached a peak in popularity in the early 1970s. Slowly, however, the wear and tear of years of dictatorial power had not slowed the repression, even after the defeat of the leftist guerrillas. The inability to deal with the economic crises of the period and popular pressure made an opening policy inevitable, which from the regime side was led by Generals Ernesto Geisel and Golbery do Couto e Silva . With
6572-776: The 1930s in Sweden ( ASEA ) and in Germany . Early commercial installations included one in the Soviet Union in 1951 between Moscow and Kashira , and a 100 kV, 20 MW system between Gotland and mainland Sweden in 1954. Before the Chinese project of 2019, the longest HVDC link in the world was the Rio Madeira link in Brazil , which consists of two bipoles of ±600 kV, 3150 MW each, connecting Porto Velho in
6696-516: The 1930s, but the rotating machinery required high maintenance and had high energy loss. Various other electromechanical devices were tested during the first half of the 20th century with little commercial success. One technique attempted for conversion of direct current from a high transmission voltage to lower utilization voltage was to charge series-connected batteries , then reconnect the batteries in parallel to serve distribution loads. While at least two commercial installations were tried around
6820-634: The 1930s, three attempts to remove Vargas and his supporters from power failed. The first was the Constitutionalist Revolution in 1932, led by São Paulo's oligarchy . The second was a Communist uprising in November 1935, and the last one a putsch attempt by local fascists in May 1938. The 1935 uprising created a security crisis in which Congress transferred more power to the executive branch. The 1937 coup d'état resulted in
6944-493: The AC equivalent line, then for a given current (where HVDC current is the same as the RMS current in the AC line), the power transmission capability when operating with HVDC is approximately 40% higher than the capability when operating with AC. Because HVDC allows power transmission between unsynchronized AC distribution systems, it can help increase system stability, by preventing cascading failures from propagating from one part of
7068-479: The AC line connections. CCC has remained only a niche application because of the advent of voltage-source converters (VSCs) which more directly address turn-off issues. Widely used in motor drives since the 1980s, voltage-source converters (VSCs) started to appear in HVDC in 1997 with the experimental Hellsjön–Grängesberg project in Sweden. By the end of 2011, this technology had captured a significant proportion of
7192-542: The Americas, with a total area of 8,515,767.049 km (3,287,956 sq mi), including 55,455 km (21,411 sq mi) of water. North to South, Brazil is also the longest country in the world, spanning 4,395 km (2,731 mi) from north to south, and the only country in the world that has the equator and the Tropic of Capricorn running through it. It spans four time zones ; from UTC−5 comprising
7316-443: The Brazilian economy. Cardoso won the 1994 election , and again in 1998 . The peaceful transition of power from Cardoso to his main opposition leader, Luiz Inácio Lula da Silva ( elected in 2002 and re-elected in 2006 ), was seen as proof that Brazil had achieved a long-sought political stability. However, sparked by indignation and frustrations accumulated over decades from corruption, police brutality , inefficiencies of
7440-432: The DC link. The disadvantages of HVDC are in conversion, switching, control, availability, and maintenance. HVDC is less reliable and has lower availability than alternating current (AC) systems, mainly due to the extra conversion equipment. Single-pole systems have availability of about 98.5%, with about a third of the downtime unscheduled due to faults. Fault-tolerant bipole systems provide high availability for 50% of
7564-592: The HVDC market. The development of higher rated insulated-gate bipolar transistors (IGBTs), gate turn-off thyristors (GTOs), and integrated gate-commutated thyristors (IGCTs), has made HVDC systems more economical and reliable. This is because modern IGBTs incorporate a short-circuit failure mode, wherein should an IGBT fail, it is mechanically shorted. Therefore, modern VSC HVDC converter stations are designed with sufficient redundancy to guarantee operation over their entire service lives. The manufacturer ABB Group calls this concept HVDC Light , while Siemens calls
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#17328007318767688-798: The Portuguese had to fight, notably the French in Rio during the 1560s , in Maranhão during the 1610s , and the Dutch in Bahia and Pernambuco , during the Dutch–Portuguese War , after the end of Iberian Union . The Portuguese colonial administration in Brazil had two objectives that would ensure colonial order and the monopoly of Portugal's wealthiest and largest colony: to keep under control and eradicate all forms of slave rebellion and resistance, such as
7812-541: The Portuguese monopoly on Brazilian trade and opening Brazil's ports to other nations. In 1809, in retaliation for being forced into exile, the Prince Regent ordered the conquest of French Guiana . With the end of the Peninsular War in 1814, the courts of Europe demanded that Queen Maria I and Prince Regent John return to Portugal, deeming it unfit for the head of an ancient European monarchy to reside in
7936-554: The Western Hemisphere was excavated in the Amazon basin of Brazil and radiocarbon dated to 8,000 years ago (6000 BC). The pottery was found near Santarém and provides evidence that the region supported a complex prehistoric culture. The Marajoara culture flourished on Marajó in the Amazon delta from AD 400 to 1400, developing sophisticated pottery, social stratification , large populations, mound building , and complex social formations such as chiefdoms . Around
8060-484: The almost-unknown Fernando Collor , who was subsequently impeached by the National Congress in 1992. Collor was succeeded by his vice-president, Itamar Franco , who appointed Fernando Henrique Cardoso Minister of Finance. In 1994, Cardoso produced a highly successful Plano Real , that, after decades of failed economic plans made by previous governments attempting to curb hyperinflation, finally stabilized
8184-712: The approval of the Golden Law . The foreign-affairs policies of the monarchy dealt with issues with the countries of the Southern Cone with whom Brazil had borders. Long after the Cisplatine War that resulted in the independence of Uruguay , Brazil won three international wars during the 58-year reign of Pedro II: the Platine War , the Uruguayan War and the devastating Paraguayan War ,
8308-449: The arrival of the Europeans, the boundaries between these groups and their subgroups were marked by wars that arose from differences in culture, language and moral beliefs. These wars also involved large-scale military actions on land and water, with cannibalistic rituals on prisoners of war . While heredity had some weight, leadership was a status more won over time than assigned in succession ceremonies and conventions. Slavery among
8432-405: The cancellation of the 1938 election and formalized Vargas as dictator, beginning the Estado Novo era. During this period, government brutality and censorship of the press increased. During World War II , Brazil remained neutral until August 1942, when the country suffered retaliation by Nazi Germany and Fascist Italy in a strategic dispute over the South Atlantic, and, therefore, entered
8556-400: The central power, coupled with old and latent social tensions peculiar to a vast, slaveholding and newly independent nation state . This period of internal political and social upheaval, which included the Praieira revolt in Pernambuco , was overcome only at the end of the 1840s, years after the end of the regency, which occurred with the premature coronation of Pedro II in 1841. During
8680-525: The commissioning of replacement thyristor converters. The development of thyristor valves for HVDC began in the late 1960s. The first complete HVDC scheme based on thyristor was the Eel River scheme in Canada, which was built by General Electric and went into service in 1972. Since 1977, new HVDC systems have used solid-state devices , in most cases thyristors . Like mercury arc valves, thyristors require connection to an external AC circuit in HVDC applications to turn them on and off. HVDC using thyristors
8804-418: The continent's interior, sharing land borders with Uruguay to the south; Argentina and Paraguay to the southwest; Bolivia and Peru to the west; Colombia to the northwest; and Venezuela , Guyana , Suriname and France (French overseas region of French Guiana ) to the north. It shares a border with every South American country except Ecuador and Chile . The brazilian territory also encompasses
8928-436: The conversion between AC and DC is referred to as the converter . Almost all HVDC converters are inherently capable of converting from AC to DC ( rectification ) and from DC to AC ( inversion ), although in many HVDC systems, the system as a whole is optimized for power flow in only one direction. Irrespective of how the converter itself is designed, the station that is operating (at a given time) with power flow from AC to DC
9052-402: The converter station area. With time, voltage-source converter systems will probably replace all installed simple thyristor-based systems, including the highest DC power transmission applications. A long-distance, point-to-point HVDC transmission scheme generally has lower overall investment cost and lower losses than an equivalent AC transmission scheme. Although HVDC conversion equipment at
9176-428: The cross-sectional area of the conductor. Transmission line conductors operating with direct current suffer from neither constraint. Therefore, for the same conductor losses (or heating effect), a given conductor can carry more power to the load when operating with HVDC than AC. Finally, depending upon the environmental conditions and the performance of overhead line insulation operating with HVDC, it may be possible for
9300-605: The demands of revolutionaries who had taken the city of Porto , John VI departed for Lisbon. There he swore an oath to the new constitution, leaving his son, Prince Pedro de Alcântara , as Regent of the Kingdom of Brazil . Tensions between Portuguese and Brazilians increased and the Portuguese Cortes , guided by the new political regime imposed by the Liberal Revolution , tried to re-establish Brazil as
9424-601: The discovery of gold by bandeirantes in the 1690s would become the new backbone of the colony's economy, fostering a gold rush which attracted thousands of new settlers to Brazil from Portugal and all Portuguese colonies around the world. This increased level of immigration in turn caused some conflicts between newcomers and old settlers. Portuguese expeditions known as bandeiras gradually expanded Brazil's original colonial frontiers in South America to its approximately current borders. In this era other European powers tried to colonize parts of Brazil, in incursions that
9548-541: The east, Brazil has a coastline of 7,491 kilometers (4,655 mi). Covering roughly half of South America's land area, it borders all other countries and territories on the continent except Ecuador and Chile . Brazil's Amazon basin includes a vast tropical forest home to diverse wildlife , a variety of ecological systems , and extensive natural resources spanning numerous protected habitats . This unique environmental heritage positions Brazil at number one of 17 megadiverse countries . The country's natural richness
9672-477: The enactment of the Amnesty Law in 1979, Brazil began a slow return to democracy , which was completed during the 1980s. Civilians returned to power in 1985 when José Sarney assumed the presidency. He became unpopular during his tenure through failure to control the economic crisis and hyperinflation he inherited from the military regime. Sarney's unsuccessful government led to the election in 1989 of
9796-407: The energy lost as heat in the wires is directly proportional to the square of the current ( energy lost as heat = current 2 ⋅ resistance ⋅ time ) , {\textstyle ({\text{energy lost as heat}}={\text{current}}^{2}\cdot {\text{resistance}}\cdot {\text{time}}),} using half the current at double the voltage reduces
9920-427: The firing angle is about 150–160° because above this, the valve would have insufficient turnoff time. Early LCC systems used mercury-arc valves , which were rugged but required high maintenance. Because of this, many mercury-arc HVDC systems were built with bypass switchgear across each six-pulse bridge so that the HVDC scheme could be operated in six-pulse mode for short maintenance periods. The last mercury arc system
10044-456: The first time, "a drought has covered all the way from the North to the country’s Southeast". It is the strongest drought in Brazil since the beginning of measurement in the 1950s, covering almost 60% of the country's territory. The drought is linked to deforestation and climate change. Brazilian topography is also diverse and includes hills, mountains, plains, highlands, and scrublands. Much of
10168-459: The highest areas. The semiarid climatic region generally receives less than 800 millimeters (31.5 in) of rain, most of which generally falls in a period of three to five months of the year and occasionally less than this, creating long periods of drought. Brazil's 1877–78 Grande Seca (Great Drought), the worst in Brazil's history, caused approximately half a million deaths. A similarly devastating drought occurred in 1915. In 2024, for
10292-526: The indigenous groups had a different meaning than it had for Europeans, since it originated from a diverse socioeconomic organization, in which asymmetries were translated into kinship relations. Following the 1494 Treaty of Tordesillas , the land now called Brazil was claimed for the Portuguese Empire on 22 April 1500, with the arrival of the Portuguese fleet commanded by Pedro Álvares Cabral . The Portuguese encountered indigenous peoples divided into several ethnic societies, most of whom spoke languages of
10416-463: The largest war effort in Brazilian history. Although there was no desire among the majority of Brazilians to change the country's form of government , on 15 November 1889, in disagreement with the majority of the Imperial Army officers, as well as with rural and financial elites (for different reasons), the monarchy was overthrown by a military coup. A few days later, the national flag
10540-579: The last 150 years. Despite its growing economic and global profile, the country continues to face high levels of corruption , crime and social inequality . Brazil is a founding member of the United Nations , the G20 , BRICS , G4 , Mercosul , Organization of American States , Organization of Ibero-American States , and the Community of Portuguese Language Countries , and also an observer state of
10664-693: The last mercury arc HVDC system (the Nelson River Bipole 1 system in Manitoba , Canada) having been put into service in stages between 1972 and 1977. Since then, all mercury arc systems have been either shut down or converted to use solid-state devices. The last HVDC system to use mercury arc valves was the Inter-Island HVDC link between the North and South Islands of New Zealand, which used them on one of its two poles. The mercury arc valves were decommissioned on 1 August 2012, ahead of
10788-534: The last phase of the monarchy, internal political debate centered on the issue of slavery. The Atlantic slave trade was abandoned in 1850, as a result of the British Aberdeen Act and the Eusébio de Queirós Law , but only in May 1888, after a long process of internal mobilization and debate for an ethical and legal dismantling of slavery in the country , was the institution formally abolished with
10912-678: The line losses by a factor of 4. While energy lost in transmission can also be reduced by decreasing the resistance by increasing the conductor size, larger conductors are heavier and more expensive. High voltage cannot readily be used for lighting or motors, so transmission-level voltages must be reduced for end-use equipment. Transformers are used to change the voltage levels in alternating current (AC) transmission circuits, but cannot pass DC current. Transformers made AC voltage changes practical, and AC generators were more efficient than those using DC. These advantages led to early low-voltage DC transmission systems being supplanted by AC systems around
11036-662: The link capacity, but availability of the full capacity is about 97% to 98%. The required converter stations are expensive and have limited overload capacity. At smaller transmission distances, the losses in the converter stations may be bigger than in an AC transmission line for the same distance. The cost of the converters may not be offset by reductions in line construction cost and power line loss. Operating an HVDC scheme requires many spare parts to be kept, often exclusively for one system, as HVDC systems are less standardized than AC systems and technology changes more quickly. In contrast to AC systems, realizing multi-terminal systems
11160-465: The naturally regenerating forest, 44% was reported to be primary forest (consisting of native tree species with no clearly visible indications of human activity) and around 30% of the forest area was found within protected areas. For 2015, 56.% of the forest area was reported to be under public ownership and 44% private ownership . Many regions have starkly different microclimates . An equatorial climate characterizes much of northern Brazil. There
11284-706: The network. These were later removed from the system completely in the mid 1980s? (1990s?) as they contained PCB . High-voltage direct current A high-voltage direct current ( HVDC ) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages between 100 kV and 800 kV. HVDC lines are commonly used for long-distance power transmission, since they require fewer conductors and incur less power loss than equivalent AC lines. HVDC also allows power transmission between AC transmission systems that are not synchronized . Since
11408-487: The new capital city of Brasília , inaugurated in 1960. Kubitschek's successor, Jânio Quadros , resigned in 1961 less than a year after taking office. His vice-president, João Goulart , assumed the presidency, but aroused strong political opposition and was deposed in April 1964 by a coup that resulted in a military dictatorship . The new regime was intended to be transitory but gradually closed in on itself and became
11532-439: The north and semiarid deserts in the northeast, to temperate coniferous forests in the south and tropical savannas in central Brazil. In Brazil, forest cover is around 59% of the total land area, equivalent to 496,619,600 hectares (ha) of forest in 2020, down from 588,898,000 hectares (ha) in 1990. In 2020, naturally regenerating forest covered 485,396,000 hectares (ha) and planted forest covered 11,223,600 hectares (ha). Of
11656-470: The northern, northeastern regions and in the Cisplatina province. The last Portuguese soldiers surrendered on 8 March 1824; Portugal officially recognized Brazilian independence on 29 August 1825. On 7 April 1831, worn down by years of administrative turmoil and political dissent with both liberal and conservative sides of politics, including an attempt of republican secession and unreconciled to
11780-514: The official Portuguese name. Some early sailors called it the "Land of Parrots". In the Guaraní language , an official language of Paraguay , Brazil is called "Pindorama", meaning 'land of the palm trees'. Some of the earliest human remains found in the Americas , Luzia Woman , were found in the area of Pedro Leopoldo , Minas Gerais and provide evidence of human habitation going back at least 11,000 years. The earliest pottery ever found in
11904-529: The political establishment and public service , numerous peaceful protests erupted in Brazil in the middle of the first term of Dilma Rousseff , who had succeeded Lula after winning election in 2010 and again in 2014 by narrow margins. Rousseff was impeached by the Brazilian Congress in 2016, halfway into her second term, and replaced by her Vice-president Michel Temer , who assumed full presidential powers after Rousseff's impeachment
12028-521: The power flow through an HVDC link can be controlled independently of the phase angle between source and load, it can stabilize a network against disturbances due to rapid changes in power. HVDC also allows the transfer of power between grid systems running at different frequencies, such as 50 and 60 Hz. This improves the stability and economy of each grid, by allowing the exchange of power between previously incompatible networks. The modern form of HVDC transmission uses technology developed extensively in
12152-542: The project was that, during wartime, a buried cable would be less conspicuous as a bombing target. The equipment was moved to the Soviet Union and was put into service there as the Moscow–Kashira HVDC system. The Moscow–Kashira system and the 1954 connection by Uno Lamm 's group at ASEA between the mainland of Sweden and the island of Gotland marked the beginning of the modern era of HVDC transmission. Mercury arc valves were common in systems designed up to 1972,
12276-402: The same voltage. This is because direct current transfers only active power and thus causes lower losses than alternating current, which transfers both active and reactive power . In other words, transmitting electric AC power over long distances inevitably results in a phase shift between voltage and current. Because of this phase shift the effective Power=Current*Voltage, where * designates
12400-521: The selection. However, some practitioners have provided some information: For an 8 GW 40 km (25 mi) link laid under the English Channel , the following are approximate primary equipment costs for a 2000 MW 500 kV bipolar conventional HVDC link (excluding way-leaving , on-shore reinforcement works, consenting, engineering, insurance, etc.) So for an 8 GW capacity between Britain and France in four links, little
12524-697: The state of Acre and the westernmost portion of Amazonas , to UTC−4 in the western states, to UTC−3 in the eastern states (the national time ) and UTC−2 in the Atlantic islands . The climate of Brazil comprises a wide range of weather conditions across a large area and varied topography, but most of the country is tropical. According to the Köppen system , Brazil hosts six major climatic subtypes: desert , equatorial , tropical , semiarid , oceanic and subtropical . The different climatic conditions produce environments ranging from equatorial rainforests in
12648-781: The state of Rondônia to the São Paulo area with a length of more than 2,500 km (1,600 mi). High voltage is used for electric power transmission to reduce the energy lost in the resistance of the wires. For a given quantity of power transmitted, doubling the voltage will deliver the same power at only half the current: power = ( voltage ) ⋅ ( current ) = ( 2 ⋅ voltage ) ⋅ ( 1 2 ⋅ current ) {\displaystyle {\text{power}}=({\text{voltage}})\cdot ({\text{current}})=(2\cdot {\text{voltage}})\cdot ({\tfrac {1}{2}}\cdot {\text{current}})} Since
12772-414: The supplier and the client. Costs vary widely depending on the specifics of the project (such as power rating, circuit length, overhead vs. cabled route, land costs, site seismology, and AC network improvements required at either terminal). A detailed analysis of DC vs. AC transmission costs may be required in situations where there is no obvious technical advantage to DC, and economical reasoning alone drives
12896-538: The terminal stations is costly, the total DC transmission-line costs over long distances are lower than for an AC line of the same distance. HVDC requires less conductor per unit distance than an AC line, as there is no need to support three phases and there is no skin effect . AC systems use a higher peak voltage for the same power, increasing insulator costs. Depending on voltage level and construction details, HVDC transmission losses are quoted at 3.5% per 1,000 km (620 mi), about 50% less than AC (6.7%) lines at
13020-445: The terrain lies between 200 meters (660 ft) and 800 meters (2,600 ft) in elevation. The main upland area occupies most of the southern half of the country. The northwestern parts of the plateau consist of broad, rolling terrain broken by low, rounded hills. The southeastern section is more rugged, with a complex mass of ridges and mountain ranges reaching elevations of up to 1,200 meters (3,900 ft). These ranges include
13144-498: The timber to European traders (mostly Portuguese, but also French) in return for assorted European consumer goods. The official Portuguese name of the land, in original Portuguese records, was the "Land of the Holy Cross" ( Terra da Santa Cruz ), but European sailors and merchants commonly called it the "Land of Brazil" ( Terra do Brasil ) because of the brazilwood trade. The popular appellation eclipsed and eventually supplanted
13268-536: The time of the Portuguese arrival, the territory of current day Brazil had an estimated indigenous population of 7 million people, mostly semi-nomadic, who subsisted on hunting, fishing, gathering, and migrant agriculture. The population comprised several large indigenous ethnic groups (e.g., the Tupis , Guaranis , Gês , and Arawaks ). The Tupi people were subdivided into the Tupiniquins and Tupinambás . Before
13392-435: The transmitted power, which is a vector product of voltage and current. Additional energy losses also occur as a result of dielectric losses in the cable insulation. For a sufficiently long AC cable, the entire current-carrying ability of the conductor would be needed to supply the charging current alone. This cable capacitance issue limits the length and power-carrying ability of AC power cables. However, if direct current
13516-519: The turn of the 20th century, the technique was not generally useful owing to the limited capacity of batteries, difficulties in switching between series and parallel configurations, and the inherent energy inefficiency of a battery charge/discharge cycle. First proposed in 1914, the grid controlled mercury-arc valve became available during the period 1920 to 1940 for the rectifier and inverter functions associated with DC transmission. Starting in 1932, General Electric tested mercury-vapor valves and
13640-452: The turn of the 20th century. Practical conversion of current between AC and DC became possible with the development of power electronics devices such as mercury-arc valves and, starting in the 1970s, power semiconductor devices including thyristors , integrated gate-commutated thyristors (IGCTs), MOS-controlled thyristors (MCTs) and insulated-gate bipolar transistors (IGBT). The first long-distance transmission of electric power
13764-400: The two DC rails, there is a phase change every 30°, and harmonics are considerably reduced. For this reason, the twelve-pulse system has become standard on most line-commutated converter HVDC systems built since the 1970s. With line commutated converters, the converter has only one degree of freedom – the firing angle , which represents the time delay between the voltage across
13888-625: The voltage across the valve is evenly shared between the thyristors. The thyristor plus its grading circuits and other auxiliary equipment is known as a thyristor level . Brazil Brazil , officially the Federative Republic of Brazil , is the largest and easternmost country in South America and Latin America . It is the world's fifth-largest country by area and one of the most populated countries . Its capital
14012-485: The voltage. Each set was insulated from electrical ground and driven by insulated shafts from a prime mover . The transmission line was operated in a constant-current mode, with up to 5,000 volts across each machine, some machines having double commutators to reduce the voltage on each commutator. This system transmitted 630 kW at 14 kV DC over a distance of 120 kilometres (75 mi). The Moutiers–Lyon system transmitted 8,600 kW of hydroelectric power
14136-534: The wake of the murder of his running mate, the defeated opposition presidential candidate Getúlio Vargas , supported by most of the military, successfully led the Revolution of 1930 . Vargas and the military were supposed to assume power temporarily, but instead closed down Congress, extinguished the Constitution, ruled with emergency powers and replaced the states' governors with his own supporters. In
14260-696: The war on the allied side . In addition to its participation in the battle of the Atlantic , Brazil also sent an expeditionary force to fight in the Italian campaign . With the Allied victory in 1945 and the end of the fascist regimes in Europe, Vargas's position became unsustainable, and he was swiftly overthrown in another military coup, with democracy "reinstated" by the same army that had ended it 15 years earlier. Vargas committed suicide in August 1954 amid
14384-478: The way that absolutists in Portugal had given in the succession of King John VI, Pedro I departed for Portugal to reclaim his daughter's crown after abdicating the Brazilian throne in favor of his five-year-old son and heir (Dom Pedro II ). As the new Emperor could not exert his constitutional powers until he came of age, a regency was set up by the National Assembly. In the absence of
14508-646: The world in both nominal and PPP terms—the largest in Latin America and the Southern Hemisphere . Classified as an upper-middle income economy by the World Bank , and a newly industrialized country by the IMF , Brazil has the largest share of wealth and the most complex economy in South America. It is also one of the world's major breadbaskets , being the largest producer of coffee for
14632-505: Was accepted on 31 August. Large street protests for and against her took place during the impeachment process. The charges against her were fueled by political and economic crises along with evidence of involvement with politicians from all the primary political parties. In 2017, the Supreme Court requested the investigation of 71 Brazilian lawmakers and nine ministers of President Michel Temer 's cabinet who were allegedly linked to
14756-401: Was also the first HVDC scheme to be equipped with self-tuning harmonic filters and to be controlled with a "Phase Locked Oscillator", a principle which subsequently became standard on all HVDC systems. It was designed in the late 1960s and went into service in 1974. It ran from Kingsnorth power station as a 59 kilometers long bipolar (3-wire) underground cable. The positive pole operating at
14880-591: Was demonstrated using direct current in 1882 at Miesbach-Munich Power Transmission , but only 1.5 kW was transmitted. An early method of HVDC transmission was developed by the Swiss engineer René Thury and his method, the Thury system, was put into practice by 1889 in Italy by the Acquedotto De Ferrari-Galliera company. This system used series-connected motor-generator sets to increase
15004-430: Was in first place in the first round, with 48.43% of the support from the electorate, and received 50.90% of the votes in the second round. On 8 January 2023, a week after Lula's inauguration, a mob of Bolsonaro's supporters attacked Brazil's federal government buildings in the capital, Brasília , after several weeks of unrest. Brazil occupies a large area along the eastern coast of South America and includes much of
15128-522: Was one of the last HVDC schemes equipped with mercury vapour rectifiers , which were ARAG/4-valves designed by English Electric. Each converter station for 266 kV consisted of two six-pulse valve bridges for 132 kV switched in series, which were each fed via a star-star and a star-delta connected transformer. Apart from the Nelson River Bipole 1 system in Canada , all later-built HVDC systems used thyristor valves. The Kingsnorth HVDC scheme could transfer
15252-442: Was replaced with a new design that included the national motto " Ordem e Progresso ", influenced by positivism . 15 November is now Republic Day , a national holiday. The early republican government was a military dictatorship, with the army dominating affairs both in Rio de Janeiro and in the states. Freedom of the press disappeared and elections were controlled by those in power. Not until 1894, following an economic crisis and
15376-642: Was shut down in 2012. The thyristor valve was first used in HVDC systems in 1972. The thyristor is a solid-state semiconductor device similar to the diode , but with an extra control terminal that is used to switch the device on at a particular instant during the AC cycle. Because the voltages in HVDC systems, up to 800 kV in some cases, far exceed the breakdown voltages of the thyristors used, HVDC thyristor valves are built using large numbers of thyristors in series. Additional passive components such as grading capacitors and resistors need to be connected in parallel with each thyristor in order to ensure that
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