GK Dürnrohr
The GK Dürnrohr (= DC short coupling Dürnrohr) was an HVDC short coupling west of the Dürnrohr substation , which served from 1983 to 1996 for the exchange of energy between Austria and Czechoslovakia . The GK Dürnrohr had a nominal transmission capacity of 550 MW . The nominal value of the DC voltage in the intermediate circuit was 145 kV . The transmission losses at maximum power were 1.4%.
Construction and planning
Planning for this facility began in 1975. This was preceded by a contract between Austria and the People's Republic of Poland to exchange electrical energy via a line running through the territory of Czechoslovakia . At the end of 1980, work began on building the facility. At the beginning of 1982 the structures were ready to the point that assembly of the components could begin. Commissioning of the plant began in mid-1983. From mid-June 1983 onwards, there was an experimental energy exchange with Czechoslovakia. The official start of operations took place on September 1, 1983.
Converter hall
The converter of the system is housed in a 29.8 m long, 15.4 m wide and 13.8 m high reinforced concrete hall, which has two bays for the converter transformers on both long sides. For the purpose of fire protection, the walls of the converter hall, which are 20 cm thick, are provided with rock wool thermal insulation. The entire hall is clad with galvanized sheet metal, which serves as shielding and weather protection.
The hall has a cellar. The air conditioning, the water cooling system for the converters and the water treatment system are housed in the basement. At the western end of the narrow side of the converter hall, only a fire protection wall was used to separate the operating building, in which there is an auxiliary control room, battery and rectifier rooms, test and storage rooms and ventilation devices for the air conditioning system. A non-openable triple-glazed window in the partition wall to the converter hall allows a view of the converter valves. The smoothing choke is located at the eastern end of the narrow side of the converter hall .
Transformers
Two three-phase power transformers with a rated power of 335 MVA each and a rated ratio of 400: 63 are used on both sides of the converter . In all converter transformers, the primary windings are star-connected, while one transformer on each side of the converter is star-connected and the other has secondary windings connected in delta. The transformers, in which the primary and secondary windings are star-connected, are identical to each other, as are the transformers with the high-voltage and delta-connected secondary windings. The transformers with the secondary winding connected in the star are not identical to those with the secondary winding connected in the delta.
Power converter
The twelve-pulse converter uses thyristors connected in series for each rectifier branch 44 with a peak reverse voltage of 4.2 kV and a nominal duration limit current of 3790 A. A total of 1056 thyristors were installed in the system. With a silicon wafer diameter of 100 mm, they were the largest thyristors in the world at the time the system was built.
Each converter consists of three thyristor towers, all of which are located in the converter hall. Each thyristor tower contains a complete twelve-pulse branch of the converter. In these thyristor towers, four thyristor modules connected in series are used for each valve function, which are arranged on two floors. An iron choke is located between the thyristor modules on one floor (i.e. the first and second or the third and fourth). A capacitor is located parallel to the thyristor modules on one floor. A surge arrester in the form of a varistor is located parallel to each valve function.
Each thyristor module consists of eleven thyristors connected in series, each of which is connected in parallel with a series circuit consisting of a capacitor and a resistor. The energy for the control electronics is also obtained from this wiring. Since the thyristors and the control electronics are at high voltage potential, the ignition pulses are transmitted via fiber optic cable. A second fiber optic cable enables the transmission of data from the thyristor module to the control electronics on earth potential . A programmable logic controller from the SIMATIC S5 system is used as the controller .
The thyristors and the chokes connected in series with them are cooled with deionized water, which is in a closed circuit. The resulting heat is transferred to a second circuit in which there is water mixed with glycol . The heat from this circuit is released to the environment via evaporative coolers with fans. For maintenance purposes, the corresponding modules are exchanged for intact modules and transported to the repair and test room. There is a telescopic lifting platform and a crane in the converter hall for this purpose.
Smoothing choke
The smoothing choke set up on the east side of the converter hall is an oil-cooled iron choke with 85 mH inductivity built by the ELIN company .
Harmonic filter
Four series resonance circuits are used as harmonic filters on both sides of the system . One of the filters consists of an air choke with 41 mH inductivity, to which an ohmic resistor with 615 Ω is connected in parallel. In series with this combination is a capacitor with 2 µF , which creates the connection to the high-voltage line. The other filter, which is also simply available on both converter sides, also consists of a capacitor with 2 µF, which is connected in series with a parallel connection of a resistor with 615 Ω and an air choke with 29 mH.
For the purpose of reactive power compensation, there is also a capacitor bank parallel to the outputs. Their value is 2 µF at the output towards the Czech Republic and 1 µF for the current output to Austria.
Static reactive power compensator
There is also a static reactive power compensator on the site of the plant , which remained in operation even after the HVDC close coupling was shut down. It consists of two groups of single-phase chokes, which are fed with 30 kV via a tertiary winding on the 380 kV / 220 kV transformers and can deliver a maximum reactive power of 200 MVar. The first throttle group went into operation in 1982, the second in 1986.
Since there would have been an enormous voltage spike in the network after the completion of the GK Wien-Südost if a load had been shed during the simultaneous export of electricity via the GK Dürnrohr and the GK Wien-Südost, there was a load shedding on the GK Dürnrohr area from 1991–1992 Thyristor-controlled reactive power compensator put into operation, which can deliver a continuous reactive power of 150 MVAr at a voltage of 400 kV and a reactive power of 580 MVAr for 0.3 s. This plant is still in operation today.
Power line to the Czech Republic
The 102 km long power line to Slavětice in the Czech Republic is laid continuously as an overhead line, which is designed on pylons to accommodate two electric circuits. Until 2008, only one 380 kV circuit was installed.
In the Czech Republic the two-level arrangement ( Danube mast picture ), in Austria the three-level arrangement ( barrel mast picture ) of the conductor cables is used. The line crosses the border at Kleinhaugsdorf .
Trivia
In 1986 the Czech Robert Ospald managed to escape to Austria over the earth wire of this high-voltage line .
Shutdown
After the synchronous connection of the power grids in Western and Eastern Europe on October 17, 1995, the system continued to operate until October 31, 1996, because Austria, unlike Germany, did not have a powerful 380 kV network at that time. It was only after some power plants in Poland were equipped with a high-performance device for regulating the network frequency that the plant could not be operated. The high-voltage switching devices were used in the substations Vienna-Southeast and South Burgenland, as were the transformers, which, however, had to be rewound to a secondary voltage of 110 kV.
By eliminating the close coupling, the maximum transferable power on the line connection from Slavětice to Dürnrohr increased to 1386 MVA. By replacing some coils of the carrier frequency systems, the transmission capacity could be increased to 1481 MVA. The installation of the second 380 kV circuit, carried out in 2008, for which the pylons of the Dürnrohr-Slavětice line are designed, doubled this value to 2962 MVA.
Since the planned sale of the system to Eastern Europe for the construction of an HVDC close coupling between the power grid of Eastern Europe and that of the former Soviet Union did not come about due to its age, the remaining components of the system were dismantled and disposed of in 2007. The converter hall is now used for operational purposes by the former operator, Verbund AG .
literature
- Austrian Journal for Electricity Industry (ÖZE) . S. 257 to 330 .
Web links
Individual evidence
Coordinates: 48 ° 19 ′ 46.4 " N , 15 ° 52 ′ 47.5" E