The up-to-date turbine pool of VE-G: A guarantor of the ...ommi.co.uk/PDF/Articles/82.pdf · An up-to-date turbine pool of VE-G OMMI (Vol. 2, Issue 3) December 2003 3 The turbine

An up-to-date turbine pool of VE-G OMMI (Vol. 2, Issue 3) December 2003

www.ommi.co.uk Fleet Profile The up-to-date turbine pool of VE-G: A guarantor of the competition in the European electricity market Dipl-Ing. Reinhardt Hassa, Vattenfall Europe Generation AG & Co. KG, Managing Director for Power Stations, P.O.B. 040280, 10061 Berlin E-mail: Reinhardt.Hassa @vattenfall.de 1 Overview of the turbines owned by VE-G Vattenfall Europe Generation (VE-G) is synonymous with the secure, resource-sparing, environmentally compatible and highly efficient generation of electricity. In order to meet this standard, existing power stations have been rehabilitated and new ones built since the early 1990s, the focus being on consistently improving conversion efficiency.

Fig. 1: Rated output (gross) of the power stations (July 2003) In the base-load segment, VE-G operates eight 500MW units at the sites of Jänschwalde and Boxberg. In addition, four new units of 800/900 MW each were built at Schwarze Pumpe, Boxberg and Lippendorf. In addition, we are operating another new unit at the Lippendorf power station that is owned by E.ON and EnBW.

Lignite-fired power stations

Gas-turbine power stations

Coal-fired power station Rostock

Base load

Intermediate

Peak loadHydropower stationsRated output Pumped storageRun-of-river incl. Goldisthal (2 PS units)

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::

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2.393 MW

2.383 MW10 MW

530 MW

Rated output PS Boxberg PS Jänschwalde PS Schwarze Pumpe PS Lippendorf (VE-G-A.)

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: : : :

7.420 MW

1.900 MW3.000 MW1.600 MW

920 MW

Rated power 968 MW

Rated power 553 MW

Rated output 11.334 MW

Lignite 65,47 %

21,11 % Hydropower

8,54 %Gas turbines

Coal 4,88 %

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:

:

:

load

http://www.ommi.co.uk

mailto:@vattenfall.de


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The peak-load and controlling-load segments are characterised by gas-turbine and hydropower stations, with pumped-storage power stations occupying the most important position. The construction of the largest pumped-storage power station in the Thuringian town of Goldisthal is currently nearing completion. This pool is completed by the coal-fired power station at Rostock for intermediate-load duty and power stations from which we buy electricity on a contractual basis. 2 Steam-turbine units The steam turbines operated by VE-G include the following units: Power station Rated output (MW) No. of turbines Year of

commissioning Jänschwalde Boxberg III Boxberg IV Schwarze Pumpe Lippendorf unit R

500 500 900 800 920

6 2 1 2 1

1982 - 1988 1979 - 1980 1999 1997 1999

2.1 The 500MW turbines For many years, VE-G has been operating eight 500MW turbine-generator units at the sites of Boxberg and Jänschwalde. The turbines are of Russian design, type K-500-166-1 and were manufactured in the period between 1977 and 1986 in the former Leningrad metal works in Saint Petersburg.

Fig. 2: Longitudinal section through a turbine K-500-166-1


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The turbine has the following parameters: Live-steam temperature 535°C Live-steam pressure 163 bar Reheat-steam temperature 535°C Exhaust-steam pressure 53 mbar According to the design, the turbine sub-units had the following turbine efficiencies: HP turbine 78.5% IP turbine 88.5% LP turbine 76.0% At a specific heat consumption of 8,830 kJ/kWh, the 500MW units, as designed, attained efficiency (net) of 32.5%. Comparisons have shown that the replacement of components in conformity with the advanced state of turbine development results in improvements in both the functions and the efficiency. The largest potential for improvement was determined for low-pressure turbines, especially since the design was less than perfect for the existing cooling-water conditions. By replacing the internal cylinders and rotors and reconfiguring the blading, a LP turbine efficiency of 86.8% was achieved, increasing it by more than 7.5%.

Fig. 3: Upgraded LP turbine of the 500MW unit

Fig. 3 shows the upgraded LP turbine, designed by ALSTOM (formerly MAN Nuremberg). The LP turbines were replaced in the years 1994 and 1995. The development of efficiency-optimized (3D) blading for HP turbines made it possible to improve the efficiency of these turbine sub-units as well.


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Typical guide vane Typical rotating blade Special features: • Standard blading • 3D profiles, integral cover bands • Torsionally pre-stressed • Milled from bars • No lining or similar features required

Fig. 4: Up-to-date 3D reaction blading A comparison with new units shows that if the type with ALPHA flow (inlet in central position and flow reversal within the HP turbine) is kept, an efficiency of approximately 87.5% for a design with first-stage nozzle control and over 90% without first-stage nozzle control can be achieved. That is why we have decided to replace the HP turbine rotors of all 500MW turbine-generator units in the next few years.

Fig. 5: Upgraded HP turbine of a 500MW unit By upgrading both the LP and HP turbines, the specific heat consumption of the turbine-generator units was reduced by 540 kJ/kWh or 6%.


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2.2 The 800/900MW turbines Planning for new lignite-fired power stations concerned the locations of Schwarze Pumpe, Boxberg and Lippendorf. Major targets to be met by the planning were: 1. Output greater than 800MW in order to optimize costs; 2. Power-station net efficiency greater than 40% in order to enhance environmental

compatibility. Transition to supercritical steam parameters, which had not been applied until then in large lignite-fired power station units, and optimization of the efficiency of components were the most important innovations aimed at attaining the target efficiency. As regards turbines, the transition to efficiency-optimized blading, particularly in HP and IP turbines, made it possible to achieve the following efficiency of turbine sub-units: HP turbine 90.5% IP turbine 93.8% The following main parameters for the turbines were determined during the planning process: Power station Schwarze Pumpe Boxberg Lippendorf Output, rated point [MW] Live-steam temperature [°C] Live-steam pressure [bar] Reheat-steam temperature [°C] Exhaust-steam pressure [mbar]

815* 547 262 565 33/46**

907 545 266 581 41

933 554 267 583 38

* (at 95% steam-boiler output) ** condenser in-line installation The design of the turbine types installed at the three locations differed slightly, depending on the manufacturer and the relevant planning period. Schwarze Pumpe power station

Fig. 6: Turbine of the Schwarze Pumpe power station


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This turbine was supplied by Siemens. In line with the state-of-the-art for new blading, 3D blading in the guide vanes of the HP turbine was used. A special feature of this turbine is the possibility to tap up to 800 t/h process steam downstream of the IP turbine. For this reason, the design provided only for two LP turbines. Boxberg power station

Fig. 7: Turbine of the Boxberg IV power station This turbine was also manufactured by Siemens. It is equipped throughout with newly developed 3D blading. In view of the output rating and the exhaust-steam pressure of 41 mbar, the design provided for three LP turbines. Lippendorf power station

Fig. 8: Turbine of the Lippendorf power station

This turbine was manufactured by ALSTOM. It is equipped throughout with newly developed 3D blading and features three LP turbines too. In accordance with the technology developed by ALSTOM, the rotors consist of single segments joined by welding.

51,7 m


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In view of the supercritical parameters, it is absolutely necessary to make all heavy-duty components from newly developed 9% chromium-steel grades. Manufacturing rotors from weldments opens up the possibility to choose materials in accordance with operating temperatures. Figs. 9 and 10 illustrate the use of materials in HP and IP turbines by the example of the ALSTOM turbine made for the Lippendorf power station.

Fig. 9: Materials used in the HP turbine

Fig. 10: Materials used in the IP turbine


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Thanks to the choice of supercritical steam parameters, optimized efficiency of individual components and, in particular, increased turbine efficiency resulting from optimized 3D blading, it has been possible for the first time to increase efficiency of large lignite-fired power-station units to more than 40% (Lippendorf: 42.8%). 3 Hydroelectric power stations 3.1 Use of pumped-storage and run-of-river power stations VE-G owns a total of 29 pumped-storage units (PSU), including the four located at the new Goldisthal power station. Power station

Rated power (MW)

Number of PSU

Input to network

PSS Markersbach 1,050 6 (reversible) 380 kV substation Röhrsdorf

PSS Hohenwarte II 320 8 220 kV substation Remptendorf

PSS Hohenwarte I 60 2 110 kV substation Remptendorf

PSS Bleiloch 80 2 110 kV substation Remptendorf

PSS Niederwartha 40 2 110 kV substation Niederwartha

PSS Wendefurth 80 2 110 kV substation Hüttenrode

PSS Geesthacht 140 3 110 kV substation Bergedorf

PSS Goldisthal 1,060 (under construction)

4 (reversible) 380 kV substation Altenfeld

The pumped-storage stations meet the requirements for grid connection in accordance with Grid Code 2000 (grid and system rules of German transmission network operators). Reactive power control by means of phase-shifting operation of the PSUs is possible as well. Any output not bound by contracts is marketed by Vattenfall Europe Trading via optimized power-station operating regimes on the electricity exchange (EEX) as well as by OTC trading. In addition, the company operates 12 run-of-river turbines at a rated output of less than 5MW and a total output of approximately 10MW. In accordance with the Renewable Energy Act (EEG), this generation can be credited as ecological power.


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3.2 The new pumped-storage station at Goldisthal After six years of construction, Vattenfall Europe is currently commissioning the 1,060MW pumped-storage power station at Goldisthal in the Thuringian forest. After the completion of commissioning by early 2004, VE-G will have the largest pumped-storage power station in Germany as far as both capacity and energy capability are concerned and the most advanced of its kind in Europe. The Goldisthal pumped-storage power station either represents the state-of-the-art in all technical disciplines or has contributed to its further development or new definition. This project meets the following targets: - provision of electrical energy in times of peak demand; - provision of fast-reaction reserve, primary and secondary controlling-power range for

transmission-network operations; - phase-shifting operation to ensure voltage stability in the transmission system. The Goldisthal PSS has been designed as a cavern-type power station. The upper and lower reservoirs are connected to the power-house cavern by two headrace and tailrace tunnels whose moderate dimensions (l x w x h = 137m x 26m x 49.5m) result from the fact that the space required to accommodate the four pumped-storage units and their auxiliaries could be minimized. Reversible pump turbines with vertical shafts serve as hydraulic machines at the Goldisthal PSS; two of the four units installed are equipped with generators with speed control in the range from 300 - 346 rpm. All pump turbines are identical. The normal net-head ranges from 280.70m to 325.00m. At a nominal head of 301.65m in turbine operation, the rated output of the pump turbines is 265 MW. This output can be attained within less than 100s from standstill. At nominal head and rated speed, the pump turbine has a power consumption of 256 MW in the pumping operation. The consistently short transition times between the various operating modes ensure that Goldisthal is in an excellent position to make a major contribution to network stability and surely will do so.


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Fig. 11 : Transition times between the operating modes

The fact that two of the four reversible pump units installed are equipped with asynchronous motor generators with speed control is an outstanding innovation and, in view of their size, a unique feature of European pump-storage power stations. In addition to allowing system control in the pumping operation too, improved turbine efficiency in part-load operation by closed-loop control is another advantage of asynchronous motor-generators with speed control. The design of the reversible-pump turbines, in particular in view of the desired speed-controlled operation, made it necessary for the consortium of contractors to carry out comprehensive hydraulic development work. If the wide range of heads that is normal in pump turbines, in connection with 0 to 100% power control in turbine operation makes already great demands on the hydraulic design, the family of characteristic curves is even more enlarged by the speed control between 300 and

AB

ST TL

T1 P1

P0 T0

213s 86s

33s 42s 98s 229s

60s 75s

422s 372s

72s 68s

171s 250s

195s 227s

99s

236s 161s

462s

314s

373s

484s

AB - out of operation ST- standstill, ready for operation, ball-slide valve clos T1 - turbine operation at full load P1 - pumping operation at full load T0 - phase shifter in direction of turbine rotation P0 - phase shifter in direction of pump rotation TL - no-load operation of turbine, not connected to network


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346 rpm. Especially great requirements were made on the cavitation-free design, ensuring maximum efficiency at the same time. This problem has been solved very successfully. Model tests performed in order to check the characteristics guaranteed by contract have shown that compared with the planning, the optimum efficiency of the variable-speed pump turbine was increased from 92.5% to 93.8% in turbine operation and from 92% to 93.7% in pumping operation. It is therefore justified to point out that the pump turbines are characterized by top efficiency, even by international standards. The range of power control in the pumping operation was increased from the 80MW required per turbine to 100 – 120 MW, depending on the head; hence the overall efficiency of pumped storage will be in the range of 80%. With a view to facilitating stock keeping and revision, Vattenfall has set great store by the identical make of all four hydraulic turbine-generator units.

Fig. 12: PSS Goldisthal, reversible pump turbine C in continuous operation 4 Gas-turbine plants Vattenfall Europe Generation operates gas turbines as peak-load units at the locations of Ahrensfelde, Thyrow, Brunsbüttel, Wedel and Hamburg-Moorburg; the electrical rated power (gross) is 968 MW. Whereas the power stations at Ahrensfelde and Thyrow were assets of the


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former VEAG that were taken over, the gas turbines at Brunsbüttel, Wedel and Hamburg-Moorburg were formerly owned by HEW. Location Electrical

output Manufacturer Type Fuel Year of

construction Brunsbüttel 4 x 64MW BBC 13 B Light

distillate 1973 - 74

Wedel 2 x 51MW KWU V 93.0 Light distillate

1971

Hamburg-Moorburg

2 x 79MW KWU V 93.2 Light distillate

1980

Ahrensfelde 4 x 38MW GE MS 6001 B Natural gas 1990 - 91 Thyrow 4 x 38MW

4 x 37MW GE MS 6001 B Natural gas

/ light distillate

1987 - 89

Gas-turbine capacities are mainly used to provide fast-reaction and continuous-reserve capacity, service the spot market and cover peak-rate consumption during the day. Furthermore, all turbines are suitable for black starts and can be used in an emergency to facilitate system recovery. In accordance with application characteristics, the focus is on high availability, reliable starting processes and excellent fast-start properties. A project for upgrading instrumentation and control of the gas-turbine power stations at Ahrensfelde and Thyrow is carried out at present with a view to centralize operating functions, shorten reaction times and optimize the operation of the units. In the future, it will be possible to control both power stations from a common control room. Data exchange between the locations will take place via two mutually redundant radio links. The establishment of an optical-fibre link is planned for some later time. Thanks to the new supervisory system, remote-start possibilities will be created for third parties (e.g. network operators). The optimization of starting processes is an important part of the upgrading concept. Specially developed software makes it possible to vary starting times within given technological limits. That way, the starting processes can be controlled within the required reaction times with a view to optimize wear. The requirements of transmission-network operators concerning fast-reaction reserve are entirely met.


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Fig. 13: Gas-turbine power station at Ahrensfelde near Berlin Several of the gas turbines at the locations of Brunsbüttel, Wedel and Moorburg are equipped with telecontrol devices. Centralized control is planned for the future. In the form of its gas turbines, Vattenfall Europe Generation owns generating plants that are characterized by high availability, short starting-times and low overheads. Greater differences between feeding into and taking off from the transmission network that are, among other things, caused by the ever increasing use of sources of renewable energy (such as wind) add to the importance of gas turbines as reserve and peak-load installations. Unlike pumped-storage power stations, gas-turbine power stations can be run without interruption for extended periods and therefore reliably compensate for any malfunctions of base-load power stations. 5 Summary VE-G has generating capacity in the base, intermediate and peak-load segments. With a total generating capacity (gross) of 11,334 MW, VE-G is ranking third among the power-generating companies in Germany. Having upgraded and refurbished its power-station pool at great expenditure, VE-G now has the most-up-to-date power-station equipment at its disposal.


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The transition to supercritical steam parameters, combined with efficiency of more than 40% for lignite-fired power stations, represents a milestone in power-station development, and future power-station projects can build on it. The concepts drawn up for the new lignite-fired power stations have proved their worth. These plants are operated in the base-load duty and attain the highest availability factors.

800/900MW units Utilization factor of the maximum capacity Standby state Scheduled energy outage Disposable energy outage Forced outage

Fig. 14 : Energy availability of power stations built in 2001/2002

The construction and operation of pumped-storage and gas-turbine stations facilitates the flexible balancing-out of standby requirements, which result, for instance, from the increased use of wind power.

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Documents

The up-to-date turbine pool of VE-G: A guarantor of the ...ommi.co.uk/PDF/Articles/82.pdf · An up-to-date turbine pool of VE-G OMMI (Vol. 2, Issue 3) December 2003 3 The turbine