Sakuma Dam
Encyclopedia
The is a dam
on the Tenryū River
, located on the border of Toyone
, Kitashitara District
, Aichi Prefecture
on the island of Honshū
, Japan
. It is one of the tallest dams in Japan and supports a 350 MW hydroelectric power station
. Nearby a frequency converter station is installed, allowing interchange of power between Japan's 50 Hz and 60 Hz AC networks.
, and it was not until the Taishō period
that development began on the Tenryū River. Private entrepreneur Fukuzawa Momosuke founded the , which later became before it was nationalized into the pre-war government monopoly in 1938. The first dam on the main stream of the Tenryu River, the Yasuoka Dam
was completed in 1935. This was followed by the Iwakura Dam
in 1938. The Hiraoka Dam
was started in 1938, but completed until 1951 due to the start of World War II
.
After the end of World War II, the American occupation authorities
ordered the dissolution of Nippon Hassoden, which was divided into regional power companies. Central Japan came under Chubu Electric Power, which inherited the various dams and projects on the Tenryū River, all of which were located in Nagano Prefecture. For develop of the hydroelectric potential of the river in Shizuoka Prefecture, the government turned to the Electric Power Development Company
. The new company, in part through foreign aid loans from the United Nations
, began work on a new dam in 1952, based on plans which had begun as early as 1921. The main contractor for the project was Hazama Corporation, and construction was completed in 1956. Construction was facilitated by the steep V-shaped walls of the site, and its proximity to the Iida Line
train (several stations of which had to be relocated once the reservoir began to fill. Construction also involved the relocation of 240 households with 296 families. The official opening ceremonies on October 28, 1957 were attended by Emperor Hirohito and Empress Kojun
and was the occasion for the issuance of a commemorative postage stamp.
s. It supplies water to both the Sakuma Hydroelectric Power Station and serves as the lower reservoir for the Shin-Toyone Hydroelectric Power Station, with a rated capacity of 350,000 kW and 1,200,000 kW respectively.
.
. In 1965 an HVDC back-to-back station was installed about 1 kilometre southwest of the power plant35°04′57"N 137°47′56"E. It was rated 300 MW and with an operating voltage of ± 125 kV. The converter station is connected to the 275 kV 50 Hz grid and the 275 kV level of the 60 Hz grid. Initially the converter used mercury arc valve
s manufactured by ASEA. In 1993 it was converted to use light triggered thyristor
s, which were installed in the same valve hall
thad had contained the mercury arc valves.
Each inverter consists of two series-connected six pulse inverters forming a twelve pulse inverter. As in many other HVDC facilities, quadravalves (serial connections of four valves forming a unit) are used. Each valve consists of 7 series-connected thyristors designed for a current of 2500 A and a blocking voltage of 6 kV. Each of the two inverters uses 84 thyristors.
The station has three transformers on the 60 Hz side. One transformer is the power supply of the station, and two 275 kV/55 kV transformers feed the valves. The transformers have their low-voltage windings connected one in a delta and other in a wye. All these transformers share a common tank. On the 50 Hz side, two 275/54 kV transformers, in separate tanks, feed the valves, again with one in delta and the other in star connection of the low-voltage windings.
The DC smoothing reactor has an inductance of 0.12 H and is designed for a current of 2400 A.
On each side filters for the 5th, 7th, 11th and 13th harmonic exist, which consist of a series connection of a capacitor, an inductor and a resistor. In addition, a high pass filter is used, which consists of a capacitor switched in series with a coil to which a resistor is switched in parallel.
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
on the Tenryū River
Tenryu River
The is a river arising from Lake Suwa in Okaya, Nagano Prefecture, grazing Aichi Prefecture and flowing through western Shizuoka Prefecture in central Honshū, Japan. With a length of , it is Japan's ninth longest river.-Geography:...
, located on the border of Toyone
Toyone, Aichi
is a village located in Kitashitara District, Aichi Prefecture, Japan. As of 2010, the village had an estimated population of 1,315 and a population density of 8.43 persons per km². The total area was 155.91 km².-Geography:...
, Kitashitara District
Kitashitara District, Aichi
is a rural district located in northeastern Aichi Prefecture, Japan.As of August 2010, the district had an estimated population of 10,797 and a population density of 19.5 persons per km²...
, Aichi Prefecture
Aichi Prefecture
is a prefecture of Japan located in the Chūbu region. The region of Aichi is also known as the Tōkai region. The capital is Nagoya. It is the focus of the Chūkyō Metropolitan Area.- History :...
on the island of Honshū
Honshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. It is one of the tallest dams in Japan and supports a 350 MW hydroelectric power station
Power station
A power station is an industrial facility for the generation of electric energy....
. Nearby a frequency converter station is installed, allowing interchange of power between Japan's 50 Hz and 60 Hz AC networks.
History
The potential of the Tenryū River valley for hydroelectric power development was realized by the Meiji government at the start of the 20th century. The Tenryū River was characterized by a high volume of flow and a fast current. Its mountainous upper reaches and tributaries were areas of steep valleys and abundant rainfall, and were sparsely populated. However, the bulk of investment in hydroelectric power generation in the region was centered on the Ōi RiverOi River
The is a river in Shizuoka Prefecture, Japan.-Geography:The Ōi River flows from the Akaishi Mountains, the branch of the Japanese Southern Alps which form the border between Shizuoka, Nagano and Yamanashi prefectures. These mountains, with peaks ranging from 2000–3000 meters, are characterized by...
, and it was not until the Taishō period
Taisho period
The , or Taishō era, is a period in the history of Japan dating from July 30, 1912 to December 25, 1926, coinciding with the reign of the Taishō Emperor. The health of the new emperor was weak, which prompted the shift in political power from the old oligarchic group of elder statesmen to the Diet...
that development began on the Tenryū River. Private entrepreneur Fukuzawa Momosuke founded the , which later became before it was nationalized into the pre-war government monopoly in 1938. The first dam on the main stream of the Tenryu River, the Yasuoka Dam
Yasuoka Dam
Yasuoka Dam is a dam in the Nagano Prefecture, Japan....
was completed in 1935. This was followed by the Iwakura Dam
Iwakura Dam
Iwakura Dam is a dam in Nagano Prefecture, Japan....
in 1938. The Hiraoka Dam
Hiraoka Dam
Hiraoka Dam is a dam in Nagano Prefecture, Japan....
was started in 1938, but completed until 1951 due to the start of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
.
After the end of World War II, the American occupation authorities
Supreme Commander of the Allied Powers
Supreme Commander of the Allied Powers was the title held by General Douglas MacArthur during the Occupation of Japan following World War II...
ordered the dissolution of Nippon Hassoden, which was divided into regional power companies. Central Japan came under Chubu Electric Power, which inherited the various dams and projects on the Tenryū River, all of which were located in Nagano Prefecture. For develop of the hydroelectric potential of the river in Shizuoka Prefecture, the government turned to the Electric Power Development Company
Electric Power Development Company
The , operating under the brand name J-POWER, formerly , is the largest electric utility in Japan. It mainly produces Electricity from Coal and Hydroelectric Power Stations. It also has a few wind farms and is currently building a nuclear plant in Ohma, Aomori prefecture, that is scheduled to...
. The new company, in part through foreign aid loans from the United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
, began work on a new dam in 1952, based on plans which had begun as early as 1921. The main contractor for the project was Hazama Corporation, and construction was completed in 1956. Construction was facilitated by the steep V-shaped walls of the site, and its proximity to the Iida Line
Iida Line
The is a Japanese railway line between Toyohashi Station in Toyohashi, Aichi Prefecture and Tatsuno Station in Tatsuno, Nagano Prefecture, operated by Central Japan Railway Company . The line links eastern Aichi Prefecture and southern Nagano Prefecture through northwestern Shizuoka Prefecture. It...
train (several stations of which had to be relocated once the reservoir began to fill. Construction also involved the relocation of 240 households with 296 families. The official opening ceremonies on October 28, 1957 were attended by Emperor Hirohito and Empress Kojun
Empress Kojun
' was empress consort of Emperor Hirohito of Japan. Born , she was the mother of the present Emperor .Her posthumous name is Kōjun, which means "fragrant purity"...
and was the occasion for the issuance of a commemorative postage stamp.
Design
Sakuma Dam is a hollow-core concrete gravity dam with several central spillwaySpillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
s. It supplies water to both the Sakuma Hydroelectric Power Station and serves as the lower reservoir for the Shin-Toyone Hydroelectric Power Station, with a rated capacity of 350,000 kW and 1,200,000 kW respectively.
Surroundings
The Sakuma Dam Reservoir is a popular attraction for canoeing and camping, due to its proximity to downtown Hamamatsu and ease of access. The surrounding area is part of the Tenryū-Okumikawa Quasi-National ParkTenryū-Okumikawa Quasi-National Park
is a quasi-national park in the Tokai region of Honshū in Japan. It is rated a protected landscape according to the IUCN. The park includes the gorges of the upper Tenryū River, Sakuma Dam and its surrounding forests, Atera Seven Falls, Chausu Mountains and Mount Horaiji. It straddles the border...
.
HVDC frequency converter
The western part of Japan uses 60 Hz and the eastern part uses 50 Hz as power grid frequencyUtility frequency
The utility frequency, line frequency or mains frequency is the frequency at which alternating current is transmitted from a power plant to the end-user. In most parts of the world this is 50 Hz, although in the Americas it is typically 60 Hz...
. In 1965 an HVDC back-to-back station was installed about 1 kilometre southwest of the power plant35°04′57"N 137°47′56"E. It was rated 300 MW and with an operating voltage of ± 125 kV. The converter station is connected to the 275 kV 50 Hz grid and the 275 kV level of the 60 Hz grid. Initially the converter used mercury arc valve
Mercury arc valve
A mercury-arc valve is a type of electrical rectifier used for converting high-voltage or high-current alternating current into direct current . Rectifiers of this type were used to provide power for industrial motors, electric railways, streetcars, and electric locomotives, as well as for...
s manufactured by ASEA. In 1993 it was converted to use light triggered thyristor
Thyristor
A thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current trigger, and continue to conduct while they are forward biased .Some sources define silicon controlled rectifiers and...
s, which were installed in the same valve hall
Valve hall
A valve hall is a building which contains the valves of the static inverters of a HVDC plant. The valves consist of thyristors, or at older plants, mercury arc rectifiers. Mercury arc rectifiers are usually supported by insulators mounted on the floor, while thyristor valves may be either...
thad had contained the mercury arc valves.
Each inverter consists of two series-connected six pulse inverters forming a twelve pulse inverter. As in many other HVDC facilities, quadravalves (serial connections of four valves forming a unit) are used. Each valve consists of 7 series-connected thyristors designed for a current of 2500 A and a blocking voltage of 6 kV. Each of the two inverters uses 84 thyristors.
The station has three transformers on the 60 Hz side. One transformer is the power supply of the station, and two 275 kV/55 kV transformers feed the valves. The transformers have their low-voltage windings connected one in a delta and other in a wye. All these transformers share a common tank. On the 50 Hz side, two 275/54 kV transformers, in separate tanks, feed the valves, again with one in delta and the other in star connection of the low-voltage windings.
The DC smoothing reactor has an inductance of 0.12 H and is designed for a current of 2400 A.
On each side filters for the 5th, 7th, 11th and 13th harmonic exist, which consist of a series connection of a capacitor, an inductor and a resistor. In addition, a high pass filter is used, which consists of a capacitor switched in series with a coil to which a resistor is switched in parallel.