There have been huge changes in the calculations, and at the same time, new changes have been made in power generation, power transmission and electricity generation.

As we all know, the rated voltage of the generator has not exceeded 30kV due to the insulation limitation of the winding. In order to reduce the transmission loss, the grid voltage has risen to 220, 500kV or higher. Therefore, the step-up transformer should be configured at the power transmission end, and the power receiving end should have a drop. Pressure transformer. ABB engineers have abandoned the insulation structure of traditional motors and developed an ultra-throated generator directly connected to the grid, which has led to a series of innovations.

Principles and Benefits of Powerformer Abb has optimized the system with an integrated concept and developed a new type of ultra-high voltage generator over a period of eight years. Used for hydroelectric power and thermal power generation, the product name is Powerformer; used in wind power generation, called Windformer; used on electric motors, it is said that the stator winding of this new type of super-throated generator is different from the conventional motor, using cable winding Centralized windings. It is a stator high-voltage winding made of XLPE cable, which avoids a series of troubles caused by excessive stator current, such as cooling problems, winding vibration and welding difficulties. Each cable is approximately 100m long and is connected using a standard cable gland. The electric field distribution of the cable is uniform, which is more in line with Michaelsville's law, which is a comparison of the electric field distribution of rectangular stator bars and circular cables.

Electric field distribution diagram of rectangular stator bar and cable winding The rotor structure of the super-pressure generator is cooled by air like the conventional motor, and the stator core is cooled by water with XLPE pipe. Powerformer simplifies the system, eliminates generator outlet switch, enclosed busbar, step-up transformer, can be directly connected to the grid, maintenance workload is reduced, system efficiency can be increased by 2%, and the cost can be saved by about 10%. Life cycle assessment (LCA) shows that Powerformer produces the same electrical energy as conventional generators, uses less fuel, has lower emissions, and has less environmental impact.

Because its inertia constant (GD2) is usually larger than that of a conventional generator, it is beneficial to the safe and stable operation of the power system. However, in terms of generators, the Powerformer is larger than conventional generators and weighs about 1.2-1.4 times that of conventional generators.

The Powerformer design parameters are shown in Table 1. The Powerformer operating parameters table developed by ABB for water and thermal power is shown in Table 2. The scope of supply of Pow-erformei is different from that of conventional generators, including the mainframe and its control and protection equipment, such as Excitation, relay protection, instrumentation and grid-connected equipment, equipment that connects the generator to the grid, including high-voltage cables, rolling switches and measuring transformers.

Table 1 Powerformer design parameters used in hydropower, thermal power plant capacity / MW voltage / kV frequency / Hz speed / r excitation mode hydropower brushless or static thermal power brushless or static table 2 Powerformer operating parameters on different power stations The sample voltage and speed remarks prototype operation, comprehensive test of the old machine transformation prototype, after a comprehensive test of the traditional generator and ultra-high-voltage generator comparison see Table 3. Copper consumption and iron consumption, copper consumption is far less than iron consumption, just and The traditional generator is the opposite. Therefore, the cooling is focused on the core. In the current design, Powerformer has two main cooling systems, the ends of the rotor and stator windings are cooled by air, and the stator core is cooled with water. The cooling water pipe is axially inserted into the stator core. The cooling water pipe is also made of a cross-linked polyethylene material, which is essentially the same as the insulating material, except that the water pipe is made of a more compact material. The use of plastic tubes eliminates the risk of short circuits between the tubes and the core, as well as eddy currents in the joints and tubes. Since the core is at a low potential, the cooling water does not have to be deionized as in conventional water-cooled stator windings. The cooling water used by Power-form can be used with ordinary tap water. The stator core cooled by water has the following advantages over the stator core cooled by air: 1 The air flow rate of the water-cooled stator is low, and the wind resistance and friction loss are reduced; 2 The water-cooled stator has no ventilation slots, which makes the motor more compact and reduces the volume of the motor.

Table 3: Traditional generators and Powerforme "compared to the traditional generator voltage is low (for the ProU8 ​​hydropower station, the test items of the 9th unit are: 1 loss, efficiency, time constant, capacity curve test; 2 cable surface potential, voltage harmonic measurement; 3 mechanical vibration and other children; 4 noise measurement; 5 load test; 6 temperature rise test; 7 no-load, short-circuit test; 8 auxiliary winding (for low-voltage power plant) load and impact on the main winding; 9 single-phase, Two-phase, three-phase sudden short-circuit test, winding single-phase grounding test; 10 lightning impulse test.) Experts believe that Power-former is promising, it saves costs and improves the reliability of power generation systems. Asked questions about the relevant issues, for example, the cable withstand voltage requirements, how the hard cable will be formed, how the cable is fixed in the slot, the vibration amplitude of the stator teeth, the sudden short-circuit current compared to the conventional size, etc. Compared with traditional motors, Powerformei has a sudden short-circuit current that is much smaller than expected. The traditional motor and Powerformer are short inside the Es-kilstuna power station. The comparison of road-time fault currents is shown in Table 4. Since environmental protection issues have attracted worldwide attention, efforts to develop renewable energy and vigorously develop wind power generation have formed a worldwide trend. In 2001 alone, the installed capacity of wind power generation worldwide increased by 6,500 MW. It has reached 24GW, which proves that wind power has become a popular energy source. Wind power technology has formed a competitive market in industrialized countries. ABB is looking at this very promising market, they use Powerformer technology. Based on the new and innovative Windformer, it is similar to Powerformer and has many attractive features compared to traditional wind turbines.

Table 4 Comparison of current between traditional motor and Powerformer internal short circuit. Traditional generator 15kV external network 150kV external network short circuit current / kA three relative ground two opposite phase short circuit single relative Windfonnei and conventional equipment compared to the newly developed Windformei is highly integrated Another example is the comparison of the main structure of Windformer with conventional wind turbines. The generator uses a synchronous motor, the stator winding is wound by a cable, and the rated voltage is 20kV. The rotor is a permanent magnet steel, and the gear transmission for the conventional motor is eliminated, so that the maintenance workload is reduced. The frequency is a high-voltage alternating current that changes with the wind speed through the rectifier into a direct current, which is transmitted by the DC cable to reduce losses. The transmission to the inverter becomes the required AC power, which is connected to the grid after being boosted by the system transformer. A Windformei consists of several wind turbines, each of which is 3 MW, each with a capacity of 40 MW. The first 3 MW wind turbines have been installed at the Nilsudden power station in Sweden.

The main advantage of Windformer is its low loss, which can control the active and reactive power separately. The difference between a wind power station equipped with Windformer and a conventional asynchronous generator is shown in Table 5. Table S. Wind power plant with Windformer and traditional asynchronous generators. Wind farm with asynchronous generators. Field Turbine Gearless Synchronous Generator Asynchronous Generator Permanent Magnet Rotor Power Factor Calibrator Diode Rectifier Soft Start No Turbine Transformer Figure End Banding Continued S Wind Farm Wind Farm DC Cable AC Cable with Asynchronous Generator Beam transmission transformer without transmission transformer offshore platform for HVDC station and transmission transformer offshore platform DC transmission cable AC transmission cable DC transmission cable DC inverter SVC power station system transformers according to the same principle, successfully developed called Motor-forniei's super-squeezing motor. It has the advantages of reducing investment, saving space, improving efficiency, and reducing maintenance. In the past, large motors used in industrial machinery such as compressors and pumps have a power range of 1000 to 5000 kW and a voltage of 3 to 15 kV. Since the voltage of the transmission line is much higher than the rated voltage of the above motor, one or more step-down transformers must be installed between the grid and the motor. These transformers not only require a large amount of cost, but also have hidden dangers such as fires and oil spills. Motorformer does not need to use a step-down transformer, it can be directly connected to the high-voltage power grid. In the Motor-former, like Powerformer, it uses a cross-linked polyethylene cable to make stator windings. The rated voltage is 35, 66, 150kV, other components. There is no change in the rotor and the base. Mmorforner uses a direct online starting method with a starting current of 2 to 5 times the rated current. Under the premise that the motor does not overheat, the appropriate parameters of the motor are obtained by optimizing the mechanical torque and the grid voltage drop. The first Mo-torfonner is a synchronous motor structure. Later, if the market demand is large, an asynchronous motor of this type will be developed.

Thanks to ABB's new process technology, the equipment used in offshore drilling platforms has been completely simplified. They have recently supplied two Motorformers to the Troll offshore drilling rig located 70km from the Norwegian Gulf. It is used for the transmission of compressor systems. Motor-former's single power is 40MW, directly connected to the 72kV bus, voltage is 70kV. It is the end of the Motorformer stator winding end.

4 Conclusion The new technology of foreign super-pressure generators has entered the commercial application stage and is becoming more mature. Japan, Canada, the United States, etc. are also closely following development. Because this new technology involves innovations in the fields of generators, power transmission and power supply, and power supply, and brings tangible economic and ecological benefits, it has also attracted great interest from domestic colleagues. Harbin Institute of Electrical Engineering, Harbin University of Science and Technology and other units are also tracking and research. It is hoped that the innovative technology of this motor industry will attract the attention of all parties concerned.

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