In order to fully ensure the reliability of the system, a frequency bypass device is installed for the frequency converter at the same time. When the frequency converter is abnormal, the frequency converter stops running, and the motor can be manually switched to operate at the power frequency. The power frequency bypass consists of three high-voltage isolation switches QS1, QS2 and QS3. It is required that QS2 and QS3 cannot be closed at the same time, and interlocking is achieved mechanically.
Keywords: frequency converter, suction blower, transformer 1, HARVERT-A06/105 high-voltage frequency conversion device principle Frequency conversion device uses multi-level series technology, 6KV system structure, composed of phase-shifting transformers, power units and controllers. The 6KV series has 21 power units, each of which forms a phase in series.
Each power cell structure and electrical performance are completely identical and interchangeable. Its circuit structure is shown in Fig. 2. It is a basic AC-DC-AC single-phase inverter circuit, and the rectifier side is a diode 3-phase full-bridge, through the IGBT inverter. The bridge performs sinusoidal PWM control and can get the waveform shown in Figure 3.
Each power unit has the same structure and is interchangeable. It is a basic AC-DC-AC single-phase inverter circuit, and the rectifier side is a diode three-phase full-bridge. Through sinusoidal PWM control of the IGBT inverter bridge, such as Waveform shown in Figure 3.
The input side is powered by a phase-shifting transformer for each unit. The secondary windings of the phase-shifting transformers are divided into three groups to form a 42-pulse rectification mode; this multi-stage phase-shift superimposed rectification method can greatly improve the current waveform at the grid side, making The net power factor under load is close to 1.
In addition, due to the independence of the transformer secondary windings, the main circuit of each power unit is relatively independent, and each power unit is equivalent to a single-phase low-voltage inverter.
On the output side, the U and V output terminals of each unit are serially connected to each other in a star configuration to directly supply power to the high voltage motor. By reorganizing the PWM waveforms of each unit, the staircase sinusoidal PWM waveform shown in FIG. 4 can be obtained. This sinusoidal waveform is good, dv/dt is small, can reduce the insulation damage to the cable and the motor, without output filter can make the output cable length is very long, the motor does not require derating, can be directly used for the transformation of old equipment At the same time, the harmonic losses of the motor are greatly reduced, the resulting mechanical vibrations are eliminated, and the mechanical stress of the bearings and blades is reduced.
When a unit fails, by turning on the soft switch node K, the unit can be bypassed out of the system without affecting the operation of other units. The inverter can continuously derate the operation, which can reduce the loss caused by shutdown in many occasions. .
2. Introduction of frequency conversion reformation scheme The #2 furnace induced draft fan is a two-sided arrangement. At present, the output adjustment of the induced draft fan is realized by manually adjusting the baffle. Due to the large redundant power of the induced draft fan, and the windage control, the resistance loss caused by the wind deflector is used, resulting in high plant electricity consumption and affecting the economic operation of the unit.
Motor Parameters Fan Parameters Model:Y1000-8 Model:G4-73-11-28D
Rated power: 1000kW rated air flow: 455000m3/h
Rated voltage: 6kV rated pressure: 6460Pa
Rated current: 119A fan speed: 742rpm
Rated frequency: 50Hz Rated speed: 743r/min
In order to fully ensure the reliability of the system, a frequency bypass device is installed for the frequency converter at the same time. When the frequency converter is abnormal, the frequency converter stops running, and the motor can be manually switched to operate at the power frequency. The power frequency bypass consists of three high-voltage isolation switches QS1, QS2 and QS3. It is required that QS2 and QS3 cannot be closed at the same time, and interlocking is achieved mechanically. When the inverter is running, QS1 and QS2 are closed and QS3 is open. When the power is running, QS3 is closed and QS1 and QS2 are disconnected.
In order to achieve the protection of the inverter fault, the inverter interlocks the 6KV switch QF. Once the inverter fails, the inverter trips QF and asks Party A to make appropriate modifications to the opening and closing circuit of the QF. When the frequency is bypassed, the inverter shall allow the QF to close and cancel the tripping signal to the QF, so that the motor can start normally through the QF closing frequency.
3. Comparison of frequency converter debugging data The measurement results of relevant parameters of China Electric Power Research Institute are shown in the following table. 1 Frequency power baffle regulation and frequency conversion speed regulation The integrated input power of 2 suction fan systems is compared with the unit load frequency baffle adjustment. Adjusted reduced combined input power 90962391571
100995523472
1101062573489
The test results show that the energy saving rate is 59% at 72% load, and the energy saving rate is as high as 46% at full load. At the same time, when the motor frequency conversion starts, the starting current will rise steadily, and the motor starts very smoothly.
4. Benefit calculation after frequency conversion transformation 1) After full-load for the whole year, after inputting 2 sets of inverters, the estimated annual energy is: 520kW*5500h=2860000kWh
At least annual electricity savings: 2860000kWh*0.326 yuan/kW.h=932,000 yuan 2) During 72% load operation in the whole year, after investing 2 sets of inverters, the estimated annual energy is: 571kW*5500h=3140500kWh
Save at least on electricity: 3140500kWh*0.32
Keywords: frequency converter, suction blower, transformer 1, HARVERT-A06/105 high-voltage frequency conversion device principle Frequency conversion device uses multi-level series technology, 6KV system structure, composed of phase-shifting transformers, power units and controllers. The 6KV series has 21 power units, each of which forms a phase in series.
Each power cell structure and electrical performance are completely identical and interchangeable. Its circuit structure is shown in Fig. 2. It is a basic AC-DC-AC single-phase inverter circuit, and the rectifier side is a diode 3-phase full-bridge, through the IGBT inverter. The bridge performs sinusoidal PWM control and can get the waveform shown in Figure 3.
Each power unit has the same structure and is interchangeable. It is a basic AC-DC-AC single-phase inverter circuit, and the rectifier side is a diode three-phase full-bridge. Through sinusoidal PWM control of the IGBT inverter bridge, such as Waveform shown in Figure 3.
The input side is powered by a phase-shifting transformer for each unit. The secondary windings of the phase-shifting transformers are divided into three groups to form a 42-pulse rectification mode; this multi-stage phase-shift superimposed rectification method can greatly improve the current waveform at the grid side, making The net power factor under load is close to 1.
In addition, due to the independence of the transformer secondary windings, the main circuit of each power unit is relatively independent, and each power unit is equivalent to a single-phase low-voltage inverter.
On the output side, the U and V output terminals of each unit are serially connected to each other in a star configuration to directly supply power to the high voltage motor. By reorganizing the PWM waveforms of each unit, the staircase sinusoidal PWM waveform shown in FIG. 4 can be obtained. This sinusoidal waveform is good, dv/dt is small, can reduce the insulation damage to the cable and the motor, without output filter can make the output cable length is very long, the motor does not require derating, can be directly used for the transformation of old equipment At the same time, the harmonic losses of the motor are greatly reduced, the resulting mechanical vibrations are eliminated, and the mechanical stress of the bearings and blades is reduced.
When a unit fails, by turning on the soft switch node K, the unit can be bypassed out of the system without affecting the operation of other units. The inverter can continuously derate the operation, which can reduce the loss caused by shutdown in many occasions. .
2. Introduction of frequency conversion reformation scheme The #2 furnace induced draft fan is a two-sided arrangement. At present, the output adjustment of the induced draft fan is realized by manually adjusting the baffle. Due to the large redundant power of the induced draft fan, and the windage control, the resistance loss caused by the wind deflector is used, resulting in high plant electricity consumption and affecting the economic operation of the unit.
Motor Parameters Fan Parameters Model:Y1000-8 Model:G4-73-11-28D
Rated power: 1000kW rated air flow: 455000m3/h
Rated voltage: 6kV rated pressure: 6460Pa
Rated current: 119A fan speed: 742rpm
Rated frequency: 50Hz Rated speed: 743r/min
In order to fully ensure the reliability of the system, a frequency bypass device is installed for the frequency converter at the same time. When the frequency converter is abnormal, the frequency converter stops running, and the motor can be manually switched to operate at the power frequency. The power frequency bypass consists of three high-voltage isolation switches QS1, QS2 and QS3. It is required that QS2 and QS3 cannot be closed at the same time, and interlocking is achieved mechanically. When the inverter is running, QS1 and QS2 are closed and QS3 is open. When the power is running, QS3 is closed and QS1 and QS2 are disconnected.
In order to achieve the protection of the inverter fault, the inverter interlocks the 6KV switch QF. Once the inverter fails, the inverter trips QF and asks Party A to make appropriate modifications to the opening and closing circuit of the QF. When the frequency is bypassed, the inverter shall allow the QF to close and cancel the tripping signal to the QF, so that the motor can start normally through the QF closing frequency.
3. Comparison of frequency converter debugging data The measurement results of relevant parameters of China Electric Power Research Institute are shown in the following table. 1 Frequency power baffle regulation and frequency conversion speed regulation The integrated input power of 2 suction fan systems is compared with the unit load frequency baffle adjustment. Adjusted reduced combined input power 90962391571
100995523472
1101062573489
The test results show that the energy saving rate is 59% at 72% load, and the energy saving rate is as high as 46% at full load. At the same time, when the motor frequency conversion starts, the starting current will rise steadily, and the motor starts very smoothly.
4. Benefit calculation after frequency conversion transformation 1) After full-load for the whole year, after inputting 2 sets of inverters, the estimated annual energy is: 520kW*5500h=2860000kWh
At least annual electricity savings: 2860000kWh*0.326 yuan/kW.h=932,000 yuan 2) During 72% load operation in the whole year, after investing 2 sets of inverters, the estimated annual energy is: 571kW*5500h=3140500kWh
Save at least on electricity: 3140500kWh*0.32
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