HVDC transformers are key components of HVDC stations. HVDC converter and inverter stations terminate long-distance DC transmission lines or DC sea cables. This type of transformer provides the interface between AC grids and high power rectifiers and are used to control the load flow over the DC transmission lines. These actors adapt the AC grid voltage to an adequate level which is suitable for feeding the valve system of DC converter and inverter.
Design options
The design concept of HVDC transformers is mainly influenced by the rated voltage, rated power and transportation requirements like dimensions, weight and mode of transportation.
Many large power HVDC converter station are located in rural areas of low infrastructure. Frequently, special geometrical profiles have to be fulfilled in order to move such transformers by railway.
Typically, HVDC transformers are single phase units containing 2 winding limbs. This concept can include either 2 parallel valve windings (two for delta or two for wye system, fig. 5.8-1) or two different valve windings. In order to reduce the total transportation height frequently the core assembly includes 2 return limbs. Due to redundancy requirements in HVDC stations 3 phase units are quite uncommon.
The valve windings are exposed to AC and DC dielectric stress and therefore a special insulation assembly is necessary. Furthermore, special lead systems connecting the turrets and windings have to be installed in order to withstand the DC voltage of rectifier. Additionally, the load current contains harmonic components of considerable energy resulting in highe r losses and increased noise. Above all, special bushings are necessary for the valve side to access upper and lower winding terminals of each system from outside. Conclusively, two identical bushings are installed for star or delta system.
For approving the proper design and quality of manufacturing special applied DC and DC polarity reversal tests have to be carried out. The test bay has to be equipped with DC test apparatus accordingly and needs to provide adequate geometry to withstand the DC test voltage.
HVDC Transformers react as coupling elements between the connected AC grids and high power rectifiers, and are necessary for adapting the voltage. They insulate the rectifier itself from the AC grid and generate a phase shift.
New HVDC applications are seen between existing, well-established networks. A back-to-back link can easily combine two different AC networks together, even with different frequencies.
Such solutions can also help customers to strengthen and optimize their networks. The changing environment provides more and more opportunities to HVDC solutions, and Siemens is prepared to provide its customers with either our solution or with converter transformers as a loose component
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Impulse voltage generator is mainly used for impulse voltage test of power equipment such as lightning impulse voltage full wave lightning impulse voltage truncation wave and operating impulse voltage wave to test insulation performance.Impulse voltage generator a power supply device that imitates impulse voltages such as lightning and operating overvoltages.It is mainly used in insulation shock withstand voltage and dielectric shock breakdown and discharge tests. Scope of application: standard lightning shock lightning cut-off wave for transformers reactors mutual transformers and other high voltage electrical appliances high voltage thyristor valve SVC(HVDC) power cables all kinds of high voltage insulators bushing operation shock and all kinds of non-standard shock wave impulse voltage test required by users.Various test waveforms (standard and non-standard waveforms user-generated waveforms) can be generated by a single set of equipment.Field of application: lightning protection and lightning test for quality inspection measurement inspection and supervision organizations power equipment manufacturers railway communications aerospace and aerospace vehicles military research units universities and meteorological departments. 900kV/67.6 kJ Lightning Impulse Voltage Generator Complete Test Equipment for Transformer Reactor Cable
Impulse voltage generator is mainly used for impulse voltage test of power equipment such as lightning impulse voltage full wave lightning impulse voltage truncation wave and operating impulse voltage wave to test insulation performance.Impulse voltage generator a power supply device that imitates impulse voltages such as lightning and operating overvoltages.It is mainly used in insulation shock withstand voltage and dielectric shock breakdown and discharge tests. Scope of application: standard lightning shock lightning cut-off wave for transformers reactors mutual transformers and other high voltage electrical appliances high voltage thyristor valve SVC(HVDC) power cables all kinds of high voltage insulators bushing operation shock and all kinds of non-standard shock wave impulse voltage test required by users.Various test waveforms (standard and non-standard waveforms user-generated waveforms) can be generated by a single set of equipment.Field of application: lightning protection and lightning test for quality inspection measurement inspection and supervision organizations power equipment manufacturers railway communications aerospace and aerospace vehicles military research units universities and meteorological departments. 900kV/67.6 kJ Lightning Impulse Voltage Generator Complete Test Equipment for Transformer Reactor Cable
Impulse voltage generator is mainly used for impulse voltage test of power equipment such as lightning impulse voltage full wave lightning impulse voltage truncation wave and operating impulse voltage wave to test insulation performance.Impulse voltage generator a power supply device that imitates impulse voltages such as lightning and operating overvoltages.It is mainly used in insulation shock withstand voltage and dielectric shock breakdown and discharge tests. Scope of application: standard lightning shock lightning cut-off wave for transformers reactors mutual transformers and other high voltage electrical appliances high voltage thyristor valve SVC(HVDC) power cables all kinds of high voltage insulators bushing operation shock and all kinds of non-standard shock wave impulse voltage test required by users.Various test waveforms (standard and non-standard waveforms user-generated waveforms) can be generated by a single set of equipment.Field of application: lightning protection and lightning test for quality inspection measurement inspection and supervision organizations power equipment manufacturers railway communications aerospace and aerospace vehicles military research units universities and meteorological departments. 900kV/67.6 kJ Lightning Impulse Voltage Generator Complete Test Equipment for Transformer Reactor Cable
