Abstract: The new scheme of “compression type high-low voltage variable frequency speed control integrated device†has high power, high efficiency, high power factor, high reliability, low cost, low harmonic, low temperature rise, low voltage safety, provincial man-hour, and province The characteristics of investment, energy saving and provincial raw materials provide an optimized high-low voltage variable frequency speed control scheme for the frequency control of 3 to 10 kV and 200 to 3000 kW medium and high voltage motors. Li Yongdong. "Digital Control System of AC Motors" Beijing: Mechanical Industry Press 2001.
Keywords: high-low pressure; Vacon inverter; frequency control
It has feature of high power, high power factor, high reliability, low cost, low harmonic, low temperature, low -voltage safe,safing-man-hours,safing-investment, safing-energy, safing-material.It offers a optimization of high/low voltage variable frequencies variable speed for 3～10kV, 200～3000kW high-middle voltage motor.
Key Word: High/Low voltage;Vacon Inverter;Variable Frequencies Variable Speed
1 Introduction According to the needs of production development, Hunchun Coal (Group) Company's Bailiancheng Mine has newly built two main fan-counter-rotating axial fans, one for each. Each fan consists of two oppositely rotating impellers that form a counter-rotating structure. In the early stage of mining, the ventilation parameters are low, but in the middle and later stages of the mining, the ventilation parameters are high. Adjustment ventilation measures must be taken to adapt to changes in the underground ventilation network and ventilation requirements in different periods. The industrial and mining sites of the wind turbines are effectively adjusted to ensure the Under the premise of stable operation of the fan, it can not only meet the requirements of the production volume and air pressure, but also maximize energy conservation.
The main fan of the Bailian Castle Coal Mine adopts two explosion-proof draw-out counter-rotating axial flow fans of the FBDCZ (formerly BDK) coal mine produced by Yanjing Mining Equipment Co., Ltd., and the two fans are used as backups. The fan model: BDK-10—NO25 explosion-proof Certificate: 52025-98 Explosion-proof class dI Air flow: 2580～8820M3/min Static pressure: 1670～4510Pa Medium density 1.2kg/m3 Motor model: YBF-450MI-10 2×250KW 592r/min Rated current 379A Rated voltage 500V F class Insulation △ connection allows temperature rise 85 °C May 2006 production. Fans are one of the main equipments for coal mine production. The normal and safe operation of wind turbines plays a crucial role in the entire coal mine system. In order to adapt to the need for ventilation adjustment of counter-rotating-axis circulation fans, especially for motor and frequency converter capacity increase, we specially select the patented “capacity-enhanced high-low voltage variable frequency speed control integrated device†manufactured by Quanshan Electronic Power Co., Ltd. of Anshan City. (China Patent Grant No. 9). The frequency conversion control part adopts the high-quality Vacon frequency converter, and the vector control type Vacon frequency converter can completely meet the application requirements in the industrial environment. This makes the control system highly reliable, easy to program, and easy to maintain.
2 Compatible high-low voltage variable frequency speed control integrated device Concise principle The frequency conversion device is composed of multi-function transformer T, low-voltage high-power frequency converter F that can be increased, and frequency-variable speed-regulating motor HM' that uses common high-voltage motor to increase voltage and capacity. And the switching device C is integrated.
This project is to use 6kV, 250kW, 10 pole explosion-proof motors, through the use of "medium voltage insulation" and low voltage wiring, capacity increase of 280kW. It also uses a multi-function transformer to provide "inverter input voltage compensation device", the 500kW inverter capacity increase to 630kW, for the motor to provide variable frequency power supply; Second, isolate and suppress the higher harmonics generated from the frequency conversion process; three For the motor to provide power frequency power, once the inverter fails, you can restore the power frequency operation mode. Utilize the universal combination switch to achieve frequency/power frequency mode switching, forward/reverse rotation switching, and master/standby unit switching.
Its electrical principle is shown in Figure 1.
2.1 Compatible Variable Frequency Device Configuration Compatible High-Low Voltage Variable Frequency Speed ​​Control Equipment Selection: QSHLVF500-O6/500. Quantity: Two sets (one for one).
Device configuration:
(1) 2 multi-function transformers. S9M-1000KVA energy-saving, maintenance-free, fully sealed, non-oil pillow transformer is used; ambient temperature is +40°C, allowing temperature rise of 55°C; both frequency-variable power supply voltage, power-frequency power supply voltage, isolation and suppression of high-order harmonics, etc. Features.
(2) 4 sets of frequency governing motor. It is the use of YBF450M2-10 type 6kV, 250kW high-voltage motor high-grade insulation, the characteristics of large internal air cooling, the motor is: Jiamusi Electric Co., Ltd. explosion-proof three-phase asynchronous motor Model: YBT-450MI-10 250KW 50Hz IP44 500V 379A F grade insulation △ then cosΦ=0.808 592r/min. The inverter used to control the motor adopts Vacon Vacon inverter with open-loop vector control function. It integrates this patented technology into the motor manufacturing process, and changes the pressure and capacity to 280kW frequency-variable speed-regulating motor HM′, so that the motor has and exceeds the frequency conversion adjustment. Some characteristics of the speed of the special motor, and more than 50% cheaper than the frequency conversion speed control special motor. High-voltage motors that operate at low pressure will further extend the life of the motor.
(3) Frequency control cabinet 2 sets. The frequency conversion unit uses world-class products and has open-loop vector control function Vacon Finland Vacon inverter (imported original). The output power is increased from 500KW to 630KW. The Vacon inverter model is: A station NXP09205A0N0SSGA1A2, B station NXP09205A0N0SSGA1A2.
(4) Mode switch cabinet 2 sets. Composed of multi-purpose switches, it has various operating modes such as variable frequency/power frequency switching, forward/reverse switching, etc. In case of special circumstances, it is switched to the power frequency start-up mode and reverse start-up mode.
(5) Two on-site operation boxes (discs). Installed near the motor, the panel is equipped with start and stop buttons, multi-turn potentiometer speed control knob, counter-rotation direction switch, motor running current and speed digital instrumentation, and fault sound and light alarms.
2.2 Compatible variable frequency device technical specifications Input voltage: 3 phase 6kV-15% ~ +10%;
Output power: 630kW;
Output frequency: 0 ~ 50HZ;
Efficiency: more than 96%;
Power factor: 0.94 or more;
Total voltage harmonics: less than 2% (far below the national standard GB/T14549-93 "Power Quality Harmonics of Public Power Networks Harmonics" limit value for the 6kV power grid is 4%, this program has been repeatedly tested by the Northeast Power Harmonics Station. Only 1.1% to 1.3%);
Start mode: frequency conversion soft start, starting current does not exceed the rated current;
Operating mode: Frequency / power frequency switching, forward / reverse switching;
Control mode: A frequency conversion device synchronizes and rotates two fans of the main fan axial fan, that is, "one for two" mode;
System control: digital and analog interfaces for system control such as PLC, DCS, and FCF;
Frequency converter cabinet dimensions:
2200 (height) + 2000 (width) + 800 (thickness) mm.
Industrial frequency switching and forward and reverse switching cabinet dimensions:
2200 (height) + 2800 (width) + 800 (thickness) mm.
Transformer size:
1780 (length) × 1040 (width) × 1720 (height) mm, gauge: 820 mm.
Motor model: YBF450M2-10; output power increased from 250kW to 280kW.
3. System Operation Overview The main fan adopts two explosion-proof counter-rotating axial flow fans, and two counter-rotating axial flow fans are used for each other. Each counter-rotating axial flow fan is composed of two relatively mounted fans. When controlling, the two fans of each counter-rotating axial flow fan require the same rotation speed, while the frequency conversion control starts and stops simultaneously, and the power frequency control is separately controlled. start. The inverter used to control the motor adopts Vacon Vacon inverter with open-loop vector control function. Two inverters are used to control two explosion-proof counter-rotating axial flow fans, and one inverter is used to simultaneously drive the counter-rotating axial flow ventilation. The two motors of the machine.
In the normal work, the A-counter-rotating-axis circulation fan is controlled by frequency conversion and the B-axis counter-rotating-axis circulation fan is used for backup. Each counter-rotating axial flow fan has its own power frequency and frequency conversion control function, and its power frequency control is frequency control standby. When the A-stage counter-rotating axial flow fan is controlled by frequency conversion and maintenance, the standby B-stage counter-rotating axial flow fan is controlled by frequency conversion. When A, B two counter-rotating axial fan frequency control simultaneous maintenance, start A Taiwan counter-rotating axial flow fan frequency control work, use the throttle to control the ventilation volume, when the A Taiwan counter-rotating axial flow fan frequency control Also at the same time when maintenance is needed, start the B-station to control the power frequency control of the rotary shaft circulation fan. Ventilation safety is ensured by the fans.
3.1 The realization of the control system Each explosion-proof counter-rotating axial flow fan requires two control modes: direct frequency control by the machine and centralized PID control by the upper computer. Each explosion-proof counter-rotating axial flow fan has frequency conversion control and power frequency control switching function.
The coal mine three-phase power is 6000V alternating current, taking into account the one-time high-voltage motor variable frequency control, poor security and other reasons. A variable-capacity high-low voltage variable frequency speed control integrated device is adopted, and a step-down transformer is used to reduce the voltage of 6000V to 500V, and then the Vacon inverter of Finland with a voltage level of 380V to 500V is used for frequency conversion control. The motor is also replaced by a high-voltage 6000V motor and a low-voltage 500V motor, which reduces investment and improves system reliability.
Finnish Vacon Vacon inverters have programmable functions. The Vacon programming tool Vacon NC1131-3 Engineering is a graphical programming tool that conforms to the IEC 61131-3 standard and can be used to design Vacon NX special control logic and parameters. It contains basic function modules and advanced function modules such as various filters, PID controllers and integrators. The NC1131-3 can create parameters, fault information and other application-related features.
The PID control application macro of Vacon Vacon inverter is used according to the control requirements. The PID control application macro has two control functions, which are source A and source B respectively. The source A is controlled by PID and the source B is controlled by direct frequency. , Weiken inverter control terminal wiring diagram shown in Figure 2.
Inverter input signals are:
P1 : source B potentiometer frequency reference.
AI2: Source A PID control pressure feedback actual value.
K1 : Source A motor start/stop.
K2 : Forward/reverse.
K3: Fault reset.
K4: source B direct frequency start/stop K5: forward/reverse.
K6: Control source A/B selection terminal.
Inverter input signals are:
Analog AO1: Motor speed.
Relay RO1: Drive fault.
Relay RO2: The inverter is running.
The source A control is effective when the switch K6 is closed, the control mode is PID control, the setpoint AI1 of the potentiometer P1 is given value, and the actual air pressure feedback value is AI2, and the start, stop and forward/reverse control of the frequency converter is controlled by K1, K2 Control, PID control block diagram shown in Figure 3. The PID control keeps the mine wind pressure at the wind pressure setting value.
The source B control is effective when the switch K6 is off. The control mode is direct frequency control. The setpoint AI1 is the setpoint value of the potentiometer P1. The actual air pressure feedback value is used for display. The start, stop, and forward/reverse control of the inverter is controlled by K4, K5 control, according to the wind pressure setting value to control the fan speed so that the mine wind pressure reaches the required value.
Switch K3 is used for inverter fault reset. The analog output AO1 is set as the motor speed, the tachometer on the control panel shows the motor speed, the relay RO1 is used for the inverter fault indication, and the relay RO2 is used for the inverter running indication.
4. Actual operating conditions of the frequency converter on-site main ventilator (1) On June 20th, the No.1 Main Fan No.1 and the frequency conversion device began operation.
The following data is the operating parameters of the No. 1 fan obtained on August 24:
1. Static pressure: 629Pa
2. Air volume: 70m3/s
3. The operating temperature of the motor is 46 °C (temperature of 28 °C in late August)
4. The operating temperature of the transformer is 35 °C (temperature of 28 °C in late August)
5. Operating frequency: 42.9Hz (513rpm)
6. Operating current: 242A (1# motor: 130A; 2# motor: 113A)
7. High side voltage: 6300V; High side current: 7.7A (A phase) 9.2A (C phase)
8. Active power: 80KVA
9. Reactive power: 21KVA
10. Power factor: 0.96
11. No. 2 of the main fan No. 1 electricity consumption statistics (electricity bureau):
(II) Operation data of No. 2 fan of Bailian City Mine on September 23. 1. Static pressure: 559Pa
2. Air volume: 74.9m3/s
3. The operating temperature of the motor is 46 °C (temperature of 28 °C in late August)
4. Transformer operating temperature 38 °C
5. Operating frequency: 32.06Hz (513rpm)
6. Operating current: 240A
7. Torque: 15%
8. Power: 9.7%
9. High side voltage: 6300V; High side current: 6.3A
10. Active power: 62.72KVA
11. Reactive power: 16.83KVA
12. Power factor: 0.96
Compatible high-low voltage variable frequency speed control integrated device has the following advantages compared with other frequency conversion speed control methods:
1. high efficiency. The frequency conversion system efficiency is greater than 96%. Among them, the rated efficiency of the inverter is about 98%, the rated efficiency of the energy-saving transformer is about 98.8%, and the motor reduces the current density and copper loss due to the enlarged wire gauge, and the rated efficiency can be increased by 0.5 to 5 percentage points. The project motor efficiency is increased by 5 percentage points.
2. High reliability. One is the use of oil-free pillow-sealed transformers or dry-type transformers, all of which are maintenance-free. The second is the selection of mature technology, low-voltage large-capacity frequency converter is safe and reliable, and the service life is as long as 70,000 hours. The service life of the cooling fan in one of the wearing parts is 8 years (2 to 3 years in other inverter manuals), and the lifetime of the electrolytic capacitors in the 2 wearing parts is 15 years (4 to 5 years in other inverter manuals. ). The third is the use of high-grade insulated motors running in low voltage variable frequency operating conditions, the insulation life can be described as infinitely long. Fourth, there is a frequency conversion/power frequency switching switch. In case of a fault in the inverter, it can be switched to the start-up mode of the industrial frequency in time. Even if the frequency is running, the motor can still be increased in capacity.
3. Low pressure safety. Because the transformer is isolated from high/low voltage, the operating voltage from the output side of the transformer → inverter → motor is only a few hundred volts, which is quite safe and easy to operate and maintain. At the same time, the high-pressure corona of the motor and the high-pressure vacuum cleaning fault of the frequency converter are eliminated.
4. Provincial duration. The manufacturing cycle of the transformer is as long as half a month; the supply period of the inverter is only 1 to 2 months; the high voltage motor is increased to about 1 month; the control cabinet processing is not more than 1 week; installation (including the laying of low voltage power cables and controls Shielded cables, do not need to re-pick the foundation and replace the pair of wheels about 1 week, the same day commissioning the day of commissioning. The total construction period (ie, the effective period) is only 1 to 3 months.
5. Provincial investment. Due to the low cost of the device, increasing capacity, and quick results, the investment recovery period is generally about 1 to 2 years. The investment recovery period for this project is approximately 2 years.
6. Energy saving. The electricity saving rate is generally 20% to 50%, and the current measurement rate of the main fan counter-rotating fan is more than 40%.
7. Provincial raw materials. Under the premise of the same raw material and component configuration, this program can improve the rated power of the motor by 1 to 3 grades, and increase the rated capacity of the inverter by 0.5 to 2 power levels; under the premise of the same power, the variable-capacity frequency conversion scheme can save the manufacturing cost. High-pressure motor steel 10% to 20%, saving high-voltage insulation material 40% to 60%. In this project, four sets of electric motors used 250kW raw materials to produce 280kW motors.
The system-wide operation is simple and the equipment maintenance is small. This effectively reduces the fan noise, reduces the mechanical impact of the motor start-stop process on the power grid and the fan, prolongs the service life of the equipment, and improves the efficiency. This type of program has the potential to promote the use of mining turbine control.
references:
Man Yongkui, Wu Chengdong. "General Inverter and Its Application" Beijing: Mechanical Industry Press 1996.
About the author: Zhao Peiguang, male, 1960.2, graduated from Jilin Staff and Workers University in 1986, majored in mechanical manufacturing technology. After graduation, he was engaged in the management of coal mine electromechanical transportation technology. He successively worked as technician and workshop director in the mechanical and electrical department of Fengguang Coal Mine of Shulan Minerals Bureau. Work; transferred to the Hunchun Minerals Bureau in the West City Coal Mine in 1992 as the deputy section chief and chief of the Department of Electrical and Mechanical Services; Sandaoling coal mine as deputy chief mechanical and electrical, mechanical and electrical mine; the West City coal mine electrical and mechanical mine chief, Bailian coal mine electrical and mechanical mine chief, responsible for the entire mine Mechanical and electrical transport management work.