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HISTORY
25-Hz At Niagara
Falls
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Thomas J. Blalock and Craig A. Woodworth | ||
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Meanwhile, in the United States, construction of the Niagara Power Project by the Power Authority of the State of New York (now known as the New York Power Authority) was delayed until 1957 due to political considerations. This huge facility (named the Robert Moses Plant after New York's master builder of public works and the chairman of the power authority) is located at Lewiston, New York, across the Niagara River from the Sir Adam Beck stations. The largest ever built in the Niagara region, the plant originally contained 13 60-Hz turbine-generators that were rated at 150 MW each. Later, these units were all rebuilt to 193.5-MW capacity, or over 2,500 MW total. Water was supplied via two tunnels from a location on the Niagara River above the falls. This project also included the Lewiston Reservoir and the pumped-storage Lewiston Pump Generating Plant that contained 12 generating units of 20-MW capacity each. When operating as synchronous motors to pump water back into the reservoir, each of these units candevelop 37,500 hp. During periods of low load, as well as during summer night hours when the water diversion can be increased, power from the main Robert Moses Plant is used to refill the reservoir. Then during the daytime peak demand period, the reservoir water drives both the Lewiston Pump Plant and the Robert Moses Plant generators. To acquire the land necessary for this massive project, Robert Moses was perfectly content to dispossess the Tuscarora Indians who inhabited the land, just as he often had done with residents of New York City who happened to be in the way of his public works projects there (such as the controversial Cross Bronx Expressway). Power System InterconnectionsInterconnections among some of the Niagara Falls power plants were made at an early date. The Rankine Station was connected with the Adams Stations via 12-kV cables run beneath the roadway of a bridge that spanned the gorge below Niagara Falls and to the Cataract Power & Conduit Company (the wholesale electric power provider in Buffalo) via 22-kV overhead lines that crossed the Niagara River at Buffalo. The Rankine Station was also connected to the Electrical Development Company station by means of underground cables. These interconnections enabled the Cataract Power & Conduit Company to purchase power from both the Rankine and the Electrical Development stations in Canada. In addition, Cataract Power also had an interconnection with the Niagara, Lockport, and Ontario Power Company that, in turn, purchased 25-Hz power from the Ontario Power plant in Canada and maintained a 60-kV transmission line to Syracuse, New York.In 1916, with increasing load and a limited supply of power from Niagara Falls, the Buffalo General Electric Company (successor to the Cataract Power & Conduit Company) began construction of a steam generating station located on the Niagara River north of Buffalo. This was originally known as the River Station and contained three 20-MW, 25-Hz turbo-generator units. In 1926, the plant was renamed the Huntley Station in honor of Charles R. Huntley, the late president of the Buffalo General Electric Company. By 1930, seven 25-Hz generators having a combined capacity of 305 MW had been installed and were in operation. Figure 1 shows the Huntley Station. In spite of the extensive development of 25-Hz hydroelectric generation at Niagara Falls, as described in part 1 of this article, surrounding areas in New York State began to develop 60-Hz power systems during the early 20th century. In 1930, two 80-MW, 60-Hz units were added at Huntley Station to enable the beginning of a conversion of 100 MW of 25-Hz load to 60 Hz. By the mid-1950s, more 60-Hz additions at Huntley had increased its capacity to 785 MW, making it the largest steam generating station in the world except for the Consolidated Edison Company's Hudson Avenue Station in New York City. However, Huntley had a higher load factor than the Hudson Avenue Station and, as a result, generated more kilowatthours on an annual basis. Frequency ChangersPrior to 1924, the Niagara, Lockport, and Ontario Power Company had in operation several synchronous frequency changers (two synchronous machines coupled together) due to the need to interconnect the 25-Hz power system in western New York State with the growing 60-Hz systems in surrounding areas. In 1924, this company installed two 6-MW "variable-ratio" frequency changers at Altmar, New York, and, just one year later, installed a third such machine at Jamestown, New York. These machines operated on the principle of the "Scherbius" drive system that recently had been developed for the accurate speed control of large ac motors driving steel rolling mills. This concept had been developed by Arthur Scherbius of Switzerland and was marketed in the United States mainly by the General Electric Company. The use of the Scherbius scheme allowed for slight changes in the speed of the frequency changer sets to accommodate minor variations in frequency on both the 25- and 60-Hz systems.Then, in 1927, two 20-MW variable-ratio-type frequency changers were installed at the town of Lockport, New York. These were not actually Scherbius machines but used a speed control system that differed somewhat in its operating details. Consequently, this style of frequency changer eventually became known in the industry as the "Lockport type." Thus, Lockport became a center of distribution for both the 25- and 60-Hz power systems in western New York State. During 1930, the Buffalo General Electric Company installed a 20-MW Scherbius frequency changer at the Huntley Generating Station. This machine actually remained in operation into the 1990s. The reason for this long operating life was that the former Bethlehem Steel plant in nearby Lackawanna, New York, had a 20-MW, 25-Hz steam turbo-generator facility in place that operated on waste gas from the plant's coke ovens. Bethlehem Steel wanted to continue to make use of that gas (actual steel-making at the plant had ceased by this time) by selling electric power to the Niagara Mohawk Power Corporation. To do that, however, the Huntley frequency changer had to be used to convert this power to 60 Hz; Bethlehem Steel paid to have this machine rehabilitated for that purpose. During the 1950s, two more frequency changers were installed by Niagara Mohawk at Gardenville, southeast of Buffalo. These were not, however, variable-ratio machines. They had been purchased from the Consolidated Edison Company of New York City, and each set consisted of a 42,000-hp, 60-Hz synchronous motor coupled to a 30-MW, 25-Hz generator. The latter machines were equipped with mechanical frame-shifting devices to enable the power flow through the sets to be controlled by adjusting the phase angles of the machines. Thus, during a portion of the 20th century, five large frequency changers were in operation in western New York State: two at Lockport, two at Gardenville, and one at Huntley Station. At one time, there had been in use two frequency changers at the Transformer House associated with the Edward Dean Adams Stations in Niagara Falls. These machines had been installed by a local chemical company to be able to purchase 60-Hz "Schoellkopf replacement power" from the New York Power Authority and convert it to 25 Hz for old motors still being used in its plant. By the year 2003, these two machines as well as the two frequency changers at Lockport had been removed, and both the Gardenville and Huntley Station machines had been taken out of service. Later DevelopmentsIn 1919, power generation in New York State was comprised of the following:
An editorial article in a 1923 issue of Electrical World stated that "Niagara Falls could never be expected to change from 25 cycles to 60 cycles." This opinion was based on the large amount of industry in the area at the time that operated on 25-Hz power. In 1945, however, a lengthy article in Electrical News & Engineering described in detail the problems to be overcome in changing southern Ontario from 25- to 60-Hz power distribution. The Edward Dean Adams Stations (see Figure 2 ), which had been placed in reserve by 1924, were returned to service at the beginning of World War II when the increased demand for electric power resulted in an increase in the permissible water diversion. The Adams Stations and the rehabilitated portion of Schoellkopf Station 3A operated at high load factors until 30 September 1961 when they were shut down and their water allotment transferred to the Robert Moses Plant. The Adams Stations themselves were demolished in the mid-1960s, but a small advertisement in the March/April 1999 issue of Preservation magazine, published by the National Trust for Historic Preservation, offered for sale the former Transformer House at that location for "adaptive re-use." The asking price was US$3 million, and the building was described as still having in place its 10-ton overhead crane. On the Canadian side of the river, the Toronto Power Station (see Figure 3) was shut down in 1974, and the Ontario Power Station (see Figure 4 and Figure 5 ) was shut down in 1997. The Rankine Station remained in service until December 2005 (on an occasional basis only), and plans are now in place to convert it into an operating museum. So ended 124 years of hydroelectric generation in the immediate vicinity of Niagara Falls (see Figure 6 ). The 60-Hz peak load in the Buffalo area did not exceed the 25-Hz peak load until 1952, and the last 25-Hz rotary converter (Edison system) substation in Buffalo was not shut down until 1956. One factor in the longevity of 25-Hz service in the city of Buffalo was that elevators could not be converted to 60-Hz operation unless they were brought completely up to then-applicable building codes. Thus, it was less expensive to pay a minimum monthly charge to retain the 25-Hz service and just leave the elevators alone. By 1994, Niagara Mohawk was no longer generating any 25-Hz power even though thecompany still had a 7-MW demand. That demand was supplied by power purchased from the Rankine and Sir Adam Beck plants in Canada, and from the Bethlehem Steel plant in Lackawanna (as described above). In fact, the Gardenville frequency changers were, by this time, normally operating to convert 25-Hz power into 60-Hz power because there was surplus 25-Hz power available from Canada. In Canada, seven of the nine Sir Adam Beck No. 1 generators have been converted to 60 Hz. The other two 25-Hz generators and a frequency changer serve the remaining two 25-Hz customers that have a maximum load of 31 MW when the steel plant in Hamilton, Ontario, is operating. It is anticipated but not mandated that the 25-Hz system in the Niagara/Hamilton area will be decommissioned at the end of 2009. EpilogueThe beginning of the end of 25-Hz power in the western New York State area was the 1947 decision of the Niagara Mohawk Power Corporation predecessor to accept no additional 25-Hz customers and not to increase the 25-Hz service to existing customers wherever 60-Hz power was available. Later, the almost complete destruction of the Schoellkopf plants in the 1956 rockslide led to an increase in the cost of supplying 25-Hz power. The completion of the Robert Moses Plant in 1961 provided replacement power for Schoellkopf customers, but it was 60-Hz power.In 1963, Niagara Mohawk petitioned the Public Service Commission of New York State to terminate all 25-Hz service by as early as 1965. That termination was not destined to occur, however, until October 2006. Over the years, the 25-Hz load decreased as customers modernized or, as was the case with the western New York State steel industry, went out of business. The number of 25-Hz customers (all in the Buffalo area) had dwindled from 73 in 1994 to only 46 in 1998 when a tariff approved by the Public Service Commission of New York provided for the elimination of 25-Hz power service by 31 December 2007 and required a contribution from affected customers if any necessary repairs to the 25-Hz system exceeded US$25,000. In 2002, an incentive program was approved that provided for a limited matching grant to retrofit equipment for 60-Hz operation. Over time, transmission and subtransmission circuits, substations, and feeders were retired to streamline the 25-Hz system and reduce losses. In 2004, the last remaining connection (at Harper Substation in Niagara Falls) from the Rankine Station was eliminated. Subsequently, the only available 25-Hz power was from the Sir Adam Beck Station No. 1. By 12 October 2006, there were only five 25-Hz customers remaining, including the former Hotel Statler in Buffalo (for elevators) and a General Mills plant. The repair of the transmission conductors that were downed on that date and interrupted the 25-Hz service would have required contributions from the remaining few customers; they elected not to contribute. Thus ended the era of 25-Hz power service on the American side of the Niagara Frontier. For Further ReadingG.W. Davenport , The Niagara Falls Electrical Handbook Syracuse, NY: Mason , 1904.W.E. McIntyre, "Niagara Falls hydro-electric industry," Ph.D. dissertation, Clark Univ., Worcester, MA, 1951. R.B. Belfield, "The Niagara frontier," Ph.D. dissertation, Univ. Pennsylvania, Philadelphia, 1981. T.J. Blalock, "The frequency changer era," IEEE Power & Energy Mag. , vol. 1, no. 5, pp. 72–79, Sept.–Oct. 2003. E.D. Adams, Niagara Power New York: Niagara Falls Power Co., 1927. E.S. Bundy, A. Van Niekerk, and W.H. Rogers, "A 40,000-kW variable-ratio frequency converter installation," AIEE Trans. , vol. 49, pt. 1, pp. 245–256, Jan. 1930. C.A. Scarlott, "Power generation at Niagara Falls," Electric J. , vol. 27, no. 11, pp. 669–675, Nov. 1930.,p> E.M. Haacke, "Problem presented by proposal to change over Southern Ontario's power to 60-cycles," Elect. News Eng. , vol. 54, no. 22, pp. 44–47 and 71–77, Nov. 15, 1945. M. Dunn, Niagara Falls—A Pictorial Journey Niagara Falls, ON: Margaret Dunn, 1998. |
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