Shandong No. 5 Electric Power Company is a domestic 200MW unit, and No. 5 furnace is equipped with two (1, 2) two-speed induced draft fans. Induced draft fan motor parameters: model YD1000-3-8/10; rated power 2500/1250kW; rated voltage 6000V; rated current 290/151A; rated speed 746/596r/min; stator connection 2Y / â–³.
The low-speed operation of the two fans can meet the needs of the full-load operation of the unit. When the high-speed operation of a single fan is lower than that of a low-speed operation, the unit can only carry a load of 10 kW, and the power consumption is significantly increased. In order to meet the needs of frequent peak shaving of the unit, reduce the fan unit consumption, improve the automatic control level, and improve the boiler operation status, the Siemens SIMOVERTM V6SE80 type frequency converter was introduced to transform the boiler induced draft fan.
Structure, principle and performance of 6SE80 inverter The structure and working principle of 6SE80 inverter AC motor speed n=(60f/p)(1-S)(r/min) type fâ€”â€”motor stator power supply frequency , Hz; p - motor pole pairs; S - motor slip. It can be seen from the above formula that if the motor stator power supply frequency is uniformly changed, the rotation speed of the motor can be smoothly changed. The speed regulation below the fundamental frequency belongs to the constant flux constant torque regulation. Main performance of 6SE80 inverter
(1) The rectifier is rectified with 12-pulse diodes. The rectifier bridge input phase is connected in parallel with an RC circuit to limit dv/dt. The two sets of rectifier bridges increase the capacity of the DC bus voltage in series. Electrical components only need to withstand 50% of the DC bus voltage, ensuring the life of electrical components.
(2) When the motor is out of service, a thyristor that triggers the turn-on command to the DC bus is issued from the SIMANDYND closed-loop control to protect all power electronic components. If the control unit power supply disappears, the DC bus C(+)M(0) or M(0)D(-) voltage exceeds 2.5kV, and its thyristor will be turned on due to overvoltage to protect the electrical components.
(3) The IGBT module is the core component of the high-high inverter.
In addition to the inverter power supply, the IGBT has the following functions: limiting overvoltage, limiting overcurrent, controlling voltage growth rate, and measuring DC bus voltage.
(4) The filter consists of an autotransformer L and a capacitor C, which suppresses harmonics and reduces the additional loss of the motor caused by current harmonics. After filtering, the distortion of the output voltage is less than 4%.
(5) The power factor of the frequency conversion device is greater than 0.96, and the rate of change of the output voltage is less than 500V/Ls.
(6) The peak load current of the long motor cable is reduced, so there is no need to install an additional output resistor.
(7) The speed regulation stability is good, and the noise of the motor is reduced.
The influence of the induced draft fan changing the frequency regulation on the running equipment (1) When the frequency conversion is adjusted, the speed of the induced draft fan is slowly increased from zero to the required speed, which reduces the impact of the starting current on the motor. (2) The medium delivered by the induced draft fan is the flue gas generated by the combustion of the boiler. When the fan runs at high speed, the fly ash wears more on the blade. Before the change, the fan adjusts the air volume by adjusting the baffle, and then the fan baffle is opened to the maximum, and the air volume is adjusted by the frequency conversion speed regulation. When the frequency is adjusted, the motor is generally operated at the rated speed, which reduces the wear on the fan blades and the regulating baffle.
The 6SE80 inverter has the advantages of high performance, high dynamics and high reliability. It is the world's most advanced inverter. The successful application of the frequency converter on the induced draft fan demonstrates superior energy savings.
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