Lect-1_FrequencyControl

Lect-1_FrequencyControl - FREQUENCY CONTROL Lecture in...

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1 FREQUENCY CONTROL Lecture in MJ2426 Applied Heat and Power Technology, Tuesday 27 January 2008 Mikael Amelin
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2 POWER SYSTEMS Electricity has to be generated the instant it is used. Automatic control systems are necessary in all larger power systems. Electric energy cannot be stored!
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3 SYNCHRONOUS GRIDS A power system connected by AC lines and transformers constitutes a synchronous grid . There can only be one frequency in a synchronous grid. Analogy A synchronous machine can be compared to a trolley be- tween two locomotives—it must go at the same pace as the rest of the system, otherwise it will be crushed. 50 Hz 50 km/h
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4 SYNCHRONOUS GRIDS - Nordel HVDC HVD C HVDC (220 kV) (20 kV) N Krajnik Gdansk Ro st o ck Lübeck Kiel Hamburg Flensburg Ringhals Helsing- borg Cøpen- hagen Got hen- burg Malmö Karlshamn Norrköping Oskars- hamn Biast yst ok Hasle Stavanger Bergen Rj u kan Oslo Stockholm En köp i n g Nea Trondheim Tunnsjødal Umeå Sun d sval Røssåga Ran a Melfjord Svart i sen Sal t en Ofoten Kobbelv Narvik Lovi sa Olkiluoto Tal in Tartu Ri g a Klaipeda Ignalina Latvia Kaunas Vilnius HVDC Krist iansand Paide Rau m a Forsmark Kassø 0 100 200 km Luleå The power transmission network in northwestern Europe Hydro power plant Thermal power plant (CHP) Transformer or switching station 750 kV line 400 kV line 300 kV line N Joint operation link for voltages below 220 kV 220 kV line Extend 2004 Cable Overhead line 275 kV AC 75 km 220 kV AC 4295 km 130 kV AC 7 km The Swedish grid, comprises mainly 220 and 400 kV lines, switchyards and transformer stations and foreign links for alternating (AC) and direct current (DC). 400 kV AC 4 km 10643 km Planned/under construction Sweden Norway Finland Poland Kaliningrad Est oni a Lithuania Russia Belorussia Denmark Germany Ro van i em i Helsingfors Åbo Vasa Tammerfors Kemi Uleåborg HVDC (High Voltage DC) 459 km 115 km Liepaja Viborg Sl up sk Teknikredaktörerna AB 2005 HVDC Si n d i
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5 FREQUENCY RANGE The frequency of a large power system must be kept around the nominal value! Certain frequencies can harm important equipment in the power system. - Harmonic vibrations in turbine blades and shafts. - Heating of generators and transformers. Some loads might be disturbed.
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6 FREQUENCY RANGE Automatic control systems–primary control (In Sweden: 49.
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Lect-1_FrequencyControl - FREQUENCY CONTROL Lecture in...

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