With the rapid development of modern power electronics and microelectronics technologies, high-voltage, high-power variable frequency speed control devices have become increasingly sophisticated. High-voltage frequency converters refer to high-power frequency converters with an input power supply voltage of 3KV or higher. Main voltage levels include 3000V, 3300V, 6000V, 6600V, and 10000V. These high-voltage, high-power frequency converters utilize the switching action of power semiconductor devices to convert industrial frequency power into electrical energy at another frequency.
Basic Principles of High Voltage Frequency Converters
The frequency conversion process of frequency converters can be broadly classified into two categories: AC-AC and AC-DC-AC. Currently, the AC-DC-AC type is more common, and its working principle will be briefly introduced below.
Three-phase high-voltage electricity enters the high-voltage switchgear, and after input step-down and phase shifting, it supplies power to the power units in the power cabinet. Next, the control unit in the main control cabinet performs rectification, inversion control, and detection on the power units in the power cabinet through optical fiber, so that the frequency can be given as needed through the operation interface. Finally, the control unit in the control cabinet sends the control information to the power units for rectification, inversion, and other adjustments to output the required voltage level.
Electricity: Exhaust fan, forced draft fan, primary air fan, dust extraction fan, booster fan, dust removal machine, feed water pump, circulating water pump, condensate pump, slurry pump
Metallurgy: Dust collectors, ventilators, mud pumps, descaling pumps
Petrochemical: Water injection pumps, electric submersible pumps, oil transfer pumps, pipeline pumps, exhaust fans, compressors, descaling pumps
Water utilities: water supply pumps, water intake pumps
Environmental protection: sewage pumps, purification pumps, clean water pumps
Cement: Kiln induced draft fan, pressure blower, cooler dust collector, raw material mill, air supply fan, cooler exhaust fan, separator fan, main dust collector fan
Papermaking: Pulping machine; Pharmaceuticals: Cleaning pump, primary air fan, secondary air fan
Mining: Drainage pumps, exhaust fans, medium pumps, slurry pumps
Pumps, widely used in industries such as metallurgy, chemical engineering, power generation, municipal water supply, and mining, account for approximately 40% of the total energy consumption of electrical equipment, and electricity costs in water treatment plants can even account for 50% of water production costs. This is because: firstly, equipment is usually designed with a certain margin; secondly, due to changes in operating conditions, pumps need to output different flow rates. With the development of the market economy and the improvement of automation and intelligence, using high-voltage frequency converters to control the speed of pump loads is not only beneficial for improving processes and product quality, but also meets the requirements for energy conservation and economical equipment operation, and is an inevitable trend for sustainable development. The benefits of speed control for pump loads are numerous. Application examples show that most have achieved good results (some achieving energy savings of up to 30%-40%), significantly reducing water production costs in water treatment plants, improving automation levels, facilitating pressure reduction operation of pumps and pipelines, reducing leakage and pipe bursts, and extending equipment lifespan.
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