CN205490284U - Controlling means based on high -power asynchronous motor frequency conversion and soft start - Google Patents

Abstract

The utility model relates to a control device based on frequency conversion and soft start of a high-power asynchronous motor. The output end of the selection cabinet is connected to the main junction box of the asynchronous motor through cables, the variable frequency soft start selection cabinet is connected to the frequency converter cabinet and the soft start cabinet through cables, and the auxiliary junction box of the asynchronous motor is connected to the input end of the star sealing cabinet through cables. During normal operation, the inverter is used to control the 6kV or 10kV asynchronous motor with a power greater than or equal to 2000kW, which can save electric energy; when the inverter fails or is overhauled, the soft starter is used to start the asynchronous motor to reduce the impact of the motor starting current on the grid, and exit after the soft start is completed The soft starter operates at power frequency; the two operating modes can be freely selected to adapt to different situations, which improves the safety, reliability and flexibility of the power supply and control of the asynchronous motor.

Description

Control device based on frequency conversion and soft start of high-power asynchronous motor

technical field

The utility model belongs to the technical improvement of an asynchronous motor, in particular to a control device based on frequency conversion and starting of a high-power asynchronous motor.

Background technique

At present, the 6kV or 10kV asynchronous motor with a power greater than or equal to 2000kW changes according to the working conditions, and it has better economic benefits to use frequency converter to control and save electric energy. However, the frequency converter is a control device that requires frequent maintenance, and the power unit of the frequency converter and fuses are consumables, which will affect the normal operation of the asynchronous motor during the maintenance of the frequency converter. It is necessary to consider the power frequency operation of the motor during the maintenance of the inverter, and the direct start of the asynchronous motor of 2000kW and above will cause a large impact on the power grid and cause voltage fluctuations, so it needs to be soft-started. How to reliably combine the control of the frequency converter and the control of the soft starter is an urgent problem to be solved.

Utility model content

The purpose of the utility model is to provide a control device based on frequency conversion and soft start of a high-power asynchronous motor, aiming at solving the above-mentioned technical problems.

The utility model is achieved in this way, a control device based on frequency conversion and soft start of a high-power asynchronous motor, the control device includes an asynchronous motor feed cabinet, a frequency conversion soft start selection cabinet, a frequency converter cabinet, a soft start cabinet, an And the sealing star cabinet, the output end of the asynchronous motor feed cabinet is connected to the input end of the frequency conversion soft start selection cabinet through a cable, and the output end of the frequency conversion soft start selection cabinet is connected to the main junction box of the asynchronous motor through a cable , the frequency conversion soft start selection cabinet is respectively connected to the frequency converter cabinet and the soft start cabinet through cables, and the auxiliary junction box of the asynchronous motor is connected to the input end of the star sealing cabinet through cables.

A further technical solution of the utility model is: the control device also includes a PLC control system, which is used to collect switching signals and analog signals, and issue instructions to control the operation of the asynchronous motor feeder cabinet, soft starter cabinet, and frequency converter cabinet.

The further technical scheme of the utility model is: the asynchronous motor feeder cabinet is provided with a vacuum circuit breaker QF, a first current transformer, a lightning arrester, a grounding knife switch, and a first microcomputer comprehensive protection device, and the vacuum circuit breaker QF The output terminal is connected to the input terminal of the first current transformer, the output terminal of the first current transformer is respectively connected to one end of the lightning arrester and one end of the grounding knife switch, and the input terminals of the first microcomputer integrated protection device are respectively Connect the sampling end of the vacuum circuit breaker QF, the sampling end of the first current transformer and the sampling end of the grounding knife switch, the other end of the lightning arrester is grounded, and the other end of the grounding knife switch is grounded.

The further technical solution of the utility model is: the first microcomputer comprehensive protection device is equipped with a current quick-break protection unit, a longitudinal differential protection unit, an inverse time limit protection unit and a single-phase grounding protection unit.

The further technical scheme of the utility model is: the frequency conversion soft-start selection cabinet is provided with an isolating knife switch QS2, a double-pole double-throw switch QS11, and a double-pole double-throw switch QS12, and the second pin of the double-pole double-throw switch QS11 The second pin of the double-pole double-throw switch QS12 is connected through mechanical and electrical interlocking, the first pin of the double-pole double-throw switch QS11 is connected to the output end of the asynchronous motor feeder cabinet, and the double-pole double-throw switch The first pin of QS12 is connected to the output end of the asynchronous motor feed cabinet, the third pin of the double-pole double-throw switch QS11 is connected to the input end of the soft starter cabinet, and the third pin of the double-pole double-throw switch QS12 One end of the isolation knife switch QS2 is connected to the output end of the inverter cabinet, and the other end of the isolation knife switch QS2 is connected to the main junction box of the asynchronous motor.

The further technical scheme of the utility model is: the soft starter cabinet is provided with a main contactor KM1, a bypass contactor KM2, a soft starter and an isolating knife switch QS1, and one end of the main contactor KM1 is connected to the double pole The third pin of the double-throw switch QS11, the other end of the main contactor KM1 is respectively connected to one end of the bypass contactor KM2 and one end of the soft starter, and the other end of the bypass contactor KM2 is connected to the soft starter The other ends of the isolating knife switch QS1 are respectively connected to one end of the isolating knife switch QS1, and the other end of the isolating knife switch QS1 is connected to the main junction box of the asynchronous motor.

The further technical solution of the present utility model is: the inverter cabinet is provided with a transformer, a second current transformer, a power unit, a control device and a second microcomputer comprehensive protection device, and the input end of the transformer is connected to the isolating knife switch The third pin of QS12, the output end of the transformer is connected to the input end of the second current transformer, the output end of the second current transformer is connected to the input end of the power unit, and the output end of the power unit Connect one end of the output busbar, the other end of the output busbar is connected to one end of the isolating knife switch QS2, the output end of the control device is connected to the control end of the power unit, and the second microcomputer integrated protection device The input end is respectively connected to the sampling end of the second current transformer and the input end of the high voltage side of the transformer.

A further technical solution of the present invention is: the second microcomputer integrated protection device is provided with an overload protection unit, a phase loss protection unit, an overvoltage protection unit, an overheat protection unit and a current limiting function unit.

The further technical solution of the present utility model is: a third current transformer and a lightning arrester are arranged in the star-sealing cabinet, the input end of the third current transformer is connected to the secondary junction box of the asynchronous motor, and the third current transformer The input end of the transformer is connected to the input end of the arrester, and the output end of the arrester is grounded.

The further technical solution of the utility model is: the switching signal includes the closing and breaking signals of the double-pole double-throw switch QS11, the double-pole double-throw switch QS12, the isolating knife switch QS1, the isolating knife switch QS2, and the vacuum circuit breaker QF; The starter self-detects no fault, running, bypass, and fault interlock trip signals; the frequency converter self-detects no fault, running, and fault interlock trip signals; the analog signal includes asynchronous motor frequency conversion operating current, power frequency operating current and operating frequency ;The control command includes allowing soft start, soft start, soft stop, soft start emergency stop; allowing the inverter to run, starting the inverter, stopping the inverter, emergency stop of the inverter, preset speed setting, continuous speed setting; The asynchronous motor feeder cabinet is allowed to close, and the asynchronous motor feeder cabinet is allowed to be interlocked and tripped.

The beneficial effects of the utility model are: the use of a frequency converter to control a 6kV or 10kV asynchronous motor with a power greater than or equal to 2000kW during normal operation can save electric energy; the use of a soft starter to start the asynchronous motor when the frequency converter is faulty or overhauled reduces the motor starting current to the power grid After the soft start is completed, exit the power frequency operation of the soft starter; the two operating modes can be freely selected to adapt to different situations, which improves the safety, reliability and flexibility of the power supply and control of the asynchronous motor.

Description of drawings

Fig. 1 is a schematic structural diagram of a control device based on frequency conversion and soft start of a high-power asynchronous motor provided by an embodiment of the present invention.

Fig. 2 is a schematic diagram of the electrical control of the motor feeder cabinet provided by the embodiment of the utility model.

detailed description

Figure 1 shows the control device based on the frequency conversion and soft start of the high-power asynchronous motor provided by the utility model, the control device includes an asynchronous motor feed cabinet, a frequency conversion soft start selection cabinet, a frequency converter cabinet, a soft start And the sealing star cabinet, the output end of the asynchronous motor feed cabinet is connected to the input end of the frequency conversion soft start selection cabinet through a cable, and the output end of the frequency conversion soft start selection cabinet is connected to the main junction box of the asynchronous motor through a cable , the frequency conversion soft start selection cabinet is respectively connected to the frequency converter cabinet and the soft start cabinet through cables, and the auxiliary junction box of the asynchronous motor is connected to the input end of the star sealing cabinet through cables.

The control device also includes a PLC control system, which is used to collect switching signals and analog signals, and issue instructions to control the operation of the asynchronous motor feeder cabinet, soft starter cabinet, and frequency converter cabinet.

The asynchronous motor feeding cabinet is provided with a vacuum circuit breaker QF, a first current transformer, a lightning arrester, a grounding knife switch, and a first microcomputer comprehensive protection device, and the output end of the vacuum circuit breaker QF is connected to the first current transformer The input end of the first current transformer, the output end of the first current transformer is respectively connected to one end of the lightning arrester and one end of the grounding knife switch, and the input end of the first microcomputer integrated protection device is respectively connected to the sampler of the vacuum circuit breaker QF end, the sampling end of the first current transformer and the sampling end of the grounding knife switch, the other end of the lightning arrester is grounded, and the other end of the grounding knife switch is grounded.

The first microcomputer integrated protection device is equipped with a current quick-break protection unit, a longitudinal differential protection unit, an inverse time limit protection unit and a single-phase grounding protection unit.

The frequency conversion soft start selection cabinet is provided with an isolating knife switch QS2, a double-pole double-throw switch QS11, and a double-pole double-throw switch QS12. The second pin of the double-pole double-throw switch QS11 is connected to the double The second pin of the knife-double-throw switch QS12, the first pin of the double-pole double-throw switch QS11 is connected to the output end of the asynchronous motor feed cabinet, and the first pin of the double-pole double-throw switch QS12 is connected to the asynchronous The output end of the motor feeder cabinet, the third pin of the double-pole double-throw switch QS11 is connected to the input end of the soft starter cabinet, and the third pin of the double-pole double-throw switch QS12 is connected to the input of the inverter cabinet One end of the isolating knife switch QS2 is connected to the output end of the inverter cabinet, and the other end of the isolating knife switch QS2 is connected to the main junction box of the asynchronous motor.

The soft starter cabinet is provided with a main contactor KM1, a bypass contactor KM2, a soft starter and an isolating knife switch QS1, one end of the main contactor KM1 is connected to the third pin of the double-pole double-throw switch QS11, The other end of the main contactor KM1 is respectively connected to one end of the bypass contactor KM2 and one end of the soft starter, and the other end of the bypass contactor KM2 and the other end of the soft starter are respectively connected to the isolation knife One end of the switch QS1, and the other end of the isolating knife switch QS1 is connected to the main junction box of the asynchronous motor.

The inverter cabinet is provided with a transformer, a second current transformer, a power unit, a control device and a second microcomputer integrated protection device, the input end of the transformer is connected to the third pin of the isolating knife switch QS12, and the transformer The output end of the second current transformer is connected to the input end of the second current transformer, the output end of the second current transformer is connected to the input end of the power unit, the output end of the power unit is connected to one end of the output busbar, and the The other end of the output busbar is connected to one end of the isolating knife switch QS2, the output end of the control device is connected to the control end of the power unit, and the input end of the second microcomputer integrated protection device is respectively connected to the second current The sampling end of the transformer and the input end of the high voltage side of the transformer.

The second microcomputer integrated protection device is provided with an overload protection unit, a phase loss protection unit, an overvoltage protection unit, an overheat protection unit and a current limiting function unit.

The star sealing cabinet is provided with a third current transformer and a lightning arrester, the input end of the third current transformer is connected to the secondary junction box of the asynchronous motor, and the input end of the third current transformer is connected to the lightning arrester The input terminal of the arrester is grounded.

The switch signal includes double-pole double-throw switch QS11, double-pole double-throw switch QS12, isolating knife switch QS1, isolating knife switch QS2, closing and breaking signals of vacuum circuit breaker QF; Bypass, fault interlock trip signal; frequency converter self-test no fault, running, fault interlock trip signal; analog signal includes asynchronous motor frequency conversion running current, power frequency running current and running frequency; the control command includes allowing soft start , soft start, soft stop, soft start emergency stop; allow the inverter to run, start the inverter, stop the inverter, emergency stop, preset speed given, continuous given speed; the asynchronous motor feeder cabinet allows closing, Asynchronous motor feeder cabinet interlock trip.

This control technology uses frequency converters to control the operation of 6kV or 10kV asynchronous motors with a power greater than or equal to 2000kW in normal conditions to save energy. The soft starter cabinet is also equipped with a bypass contactor. After the soft start is completed, the soft starter exits, and the bypass contactor is closed to run the asynchronous motor at power frequency. This control technology sets two sets of protection devices to adapt to different operation modes, and at the same time ensures the reliability of power supply and control through mechanical interlock, electrical interlock, and PLC system control.

The KYN28-12 indoor metal armored removable switchgear is used as the asynchronous motor feeder cabinet, and the cabinet is equipped with a vacuum circuit breaker QF, a current transformer, a lightning arrester, a grounding knife switch, and a microcomputer comprehensive protection device (hereinafter referred to as a microcomputer comprehensive protection device) protection device 1), etc. Microcomputer comprehensive protection device 1 is required to be equipped with current quick-break protection, longitudinal differential protection, inverse time limit protection, and single-phase grounding protection. The lower end of the asynchronous motor feeder cabinet is connected to the variable frequency soft starter selection cabinet with a cable. The variable frequency soft start selection cabinet is equipped with isolating knife switch QS2 and double-pole double-throw switches QS11, QS12. There are mechanical and electrical interlocks between them. Through the double-pole double-throw switches QS11, QS12, you can choose variable frequency operation or soft start power frequency. run. The lower end of the knife switch QS11 is connected to the soft starter cabinet with a cable, and the lower end of the knife switch QS12 is connected to the inverter cabinet with a cable. The soft starter cabinet is equipped with main contactor KM1, bypass contactor KM2, soft starter, isolating knife switch QS1. To prepare for the soft start, first close QS11, QS1, disconnect QS12, QS2, and the soft starter sends a signal after self-testing to confirm that there is no fault, and then closes the vacuum circuit breaker QF of the asynchronous motor feeder cabinet. When soft starting, first close the main contactor KM1, and then the soft starter is put into operation. After the soft starting is completed, the bypass contactor KM2 is closed, the soft starter exits, and the asynchronous motor enters power frequency operation. The inverter cabinet is equipped with a transformer, a power unit, a control device, and a microcomputer comprehensive protection device (hereinafter referred to as the microcomputer comprehensive protection device 2). The microcomputer comprehensive protection device 2 is required to be equipped with overload protection, phase loss protection, overvoltage protection, overheat protection, and current limiting functions. In the pre-operation preparation of the inverter, first close QS12, QS2, disconnect QS11, QS1, and the inverter sends a signal after self-test to confirm that there is no fault, and then close the vacuum circuit breaker QF of the asynchronous motor feeder cabinet. Put into the frequency converter during frequency conversion operation, and then run at a preset given speed or continuously variable speed according to the signal sent by the PLC control system. The lower end of the inverter cabinet is connected to the upper end of the isolating knife switch QS2 of the variable frequency soft start selection cabinet with a cable, and the lower end of the isolating knife switch QS1 of the soft start cabinet is connected to the lower end of the isolating knife switch QS2 of the variable frequency soft start selection cabinet with a cable, and then the cable is used to connect the isolating knife switch QS2 lower end and asynchronous motor main junction box. Finally, the cables are drawn out from the auxiliary junction box of the asynchronous motor and connected to the star sealing cabinet. The star sealing cabinet is equipped with a current transformer and a lightning arrester, which is mainly used for longitudinal differential protection to monitor the neutral point current of the asynchronous motor and realize the star sealing of the neutral point of the asynchronous motor.

At the same time, this technical solution is also equipped with a set of PLC control system, which is used to collect switching signal and analog signal, and also issue instructions to control the operation of asynchronous motor feeder cabinet, soft starter cabinet and frequency converter cabinet. The collected switch signals mainly include: closing and breaking signals of QS11, QS12, QS1, QS2, and QF; , Fault interlock trip signal. The collected analog signals mainly include: asynchronous motor frequency conversion operating current, power frequency operating current, operating frequency, etc. The control commands issued mainly include: allow soft start, soft start, soft stop, soft start emergency stop; allow inverter to run, start inverter, stop inverter, inverter emergency stop, preset speed setting, continuous speed setting ; The asynchronous motor feeder cabinet is allowed to close, and the asynchronous motor feeder cabinet is allowed to interlock and trip.

(1) Frequency conversion operation mode

Close QS12 and QS2 first, disconnect QS11 and QS1, and the PLC system collects relevant switching signals to confirm that QS12 and QS2 are closed in place, QS11 and QS1 are disconnected in place, and after the inverter self-tests no faults, it will send a permission to close to the asynchronous motor feeder cabinet. Gate command, and then close the vacuum circuit breaker QF of the asynchronous motor feeder cabinet. Then the equipment can be operated on site or the remote PLC system can send commands to put into the frequency converter. At this time, the asynchronous motor feeder cabinet, QS12, inverter cabinet, QS2, asynchronous motor, and star sealing cabinet are electrically connected through cables, and the asynchronous motor is controlled by the inverter, which can run at a preset given speed according to the instructions issued by the PLC control system or Continuously variable speed operation.

The setting of the microcomputer integrated protection device: before adopting frequency conversion operation, the longitudinal differential protection of the microcomputer integrated protection device 1 needs to be withdrawn from the background system of the microcomputer integrated protection device. The microcomputer integrated protection device 1 mainly protects the feeder line. Device 2 mainly protects the frequency converter and asynchronous motor. The reason for adopting this protection setting is: the current detected by the current transformer of the asynchronous motor feeder cabinet is power frequency current during variable frequency operation, and the current detected by the current transformer of the sealing star cabinet is variable frequency current, even when the asynchronous motor is running normally. The values and phase angles of the two currents are inconsistent, which will lead to misoperation of the longitudinal differential protection.

(2) Soft start power frequency operation mode

Close QS11 and QS1 first, disconnect QS12 and QS2, and the PLC system collects relevant switching signals to confirm that QS11 and QS1 are closed in place, QS12 and QS2 are disconnected in place, and after the soft starter self-tests no faults, it will send permission to the asynchronous motor feeder cabinet. Closing signal, and then close the vacuum circuit breaker QF of the asynchronous motor feeder cabinet. Then, the equipment can be operated on site or the remote PLC system can send an instruction to close the main contactor KM1, and put the soft starter into operation. At this time, the asynchronous motor feeder cabinet, QS11, KM1, soft starter, QS1, asynchronous motor, and star sealing cabinet are electrically connected through cables, and the asynchronous motor performs soft start. After the soft start is completed, the soft starter will automatically exit and issue an instruction to close the bypass contactor KM2. At this time, the asynchronous motor feeder cabinet, QS11, KM1, KM2, QS1, asynchronous motor, and star sealing cabinet are electrically connected through cables, and the asynchronous motor switches to power frequency operation.

The setting of the integrated protection device of the microcomputer: before using the soft starter to soft start the asynchronous motor, it is necessary to exit the inverse time protection of the integrated protection device 1 in the background system of the integrated protection device of the microcomputer, and put it into operation after the soft start of the asynchronous motor is completed and converted to power frequency operation The inverse time protection of the microcomputer comprehensive protection device 1. The asynchronous motor is protected by the microcomputer comprehensive protection device 1 during the soft start process of the asynchronous motor and the power frequency operation stage after the soft start is completed. The reason for using this protection setting is: if the soft start of the asynchronous motor adopts the constant current soft start mode, the asynchronous motor will run at several times (1-4 times) the rated current for a long time, and the inverse time protection will mistakenly think that the motor is overloaded And action.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model shall be included in this utility model. within the scope of protection of utility models.

Claims (9)

1. A control device based on high-power asynchronous motor frequency conversion and soft start, characterized in that the control device includes an asynchronous motor feed cabinet, frequency conversion soft start selection cabinet, frequency converter cabinet, soft start cabinet, asynchronous motor and sealed Star cabinet, the output end of the asynchronous motor feed cabinet is connected to the input end of the frequency conversion soft start selection cabinet through a cable, and the output end of the frequency conversion soft start selection cabinet is connected to the main junction box of the asynchronous motor through a cable, so The frequency conversion soft start selection cabinet is respectively connected to the frequency converter cabinet and the soft start cabinet through cables, and the secondary junction box of the asynchronous motor is connected to the input end of the star sealing cabinet through cables. 2. The control device according to claim 1, characterized in that, the control device also includes a PLC control system, which is used to collect switching signals and analog signals, and issue instructions to control asynchronous motor feed cabinets, soft starter cabinets, The operation of the inverter cabinet. 3. The control device according to claim 2, characterized in that a vacuum circuit breaker QF, a first current transformer, a lightning arrester, a grounding knife switch, and a first microcomputer comprehensive protection device are arranged in the asynchronous motor feeding cabinet, The output end of the vacuum circuit breaker QF is connected to the input end of the first current transformer, and the output end of the first current transformer is respectively connected to one end of the lightning arrester and one end of the grounding knife switch, and the first microcomputer The input end of the comprehensive protection device is respectively connected to the sampling end of the vacuum circuit breaker QF, the sampling end of the first current transformer and the sampling end of the grounding knife switch, the other end of the arrester is grounded, and the other end of the grounding knife switch grounded. 4. The control device according to claim 3, wherein the first microcomputer integrated protection device is equipped with a current quick-break protection unit, a longitudinal differential protection unit, an inverse time limit protection unit and a single-phase grounding protection unit. 5. The control device according to claim 4, characterized in that, the frequency conversion soft-start selection cabinet is provided with an isolating knife switch QS2, a double-pole double-throw switch QS11, a double-pole double-throw switch QS12, and the double-pole double-throw switch QS12 The second pin of the throw switch QS11 is connected to the second pin of the double-pole double-throw switch QS12 through mechanical and electrical interlocking, and the first pin of the double-pole double-throw switch QS11 is connected to the output end of the asynchronous motor feeder cabinet, The first pin of the double-pole double-throw switch QS12 is connected to the output end of the asynchronous motor feeder cabinet, the third pin of the double-pole double-throw switch QS11 is connected to the input end of the soft starter cabinet, and the double-pole double-throw switch QS11 is connected to the input end of the soft starter cabinet. The third pin of the double-throw switch QS12 is connected to the input end of the inverter cabinet, one end of the isolating knife switch QS2 is connected to the output end of the inverter cabinet, and the other end of the isolating knife switch QS2 is connected to the asynchronous motor main junction box. 6. The control device according to claim 5, wherein the soft starter cabinet is provided with a main contactor KM1, a bypass contactor KM2, a soft starter and an isolating knife switch QS1, and the main contactor KM1 One end of the double-pole double-throw switch QS11 is connected to the third pin, the other end of the main contactor KM1 is respectively connected to one end of the bypass contactor KM2 and one end of the soft starter, and the other end of the bypass contactor KM2 One end and the other end of the soft starter are respectively connected to one end of the isolating knife switch QS1, and the other end of the isolating knife switch QS1 is connected to the main junction box of the asynchronous motor. 7. The control device according to claim 6, wherein a transformer, a second current transformer, a power unit, a control device and a second microcomputer comprehensive protection device are arranged in the inverter cabinet, and the input of the transformer terminal is connected to the third pin of the isolating knife switch QS12, the output terminal of the transformer is connected to the input terminal of the second current transformer, and the output terminal of the second current transformer is connected to the input terminal of the power unit, The output end of the power unit is connected to one end of the output busbar, the other end of the output busbar is connected to one end of the isolating knife switch QS2, the output end of the control device is connected to the control end of the power unit, and the The input end of the second microcomputer integrated protection device is respectively connected to the sampling end of the second current transformer and the input end of the high voltage side of the transformer. 8 . The control device according to claim 7 , wherein the second microcomputer integrated protection device is provided with an overload protection unit, a phase loss protection unit, an overvoltage protection unit, an overheat protection unit and a current limiting function unit. 9. The control device according to claim 8, characterized in that, a third current transformer and a lightning arrester are arranged in the star-sealing cabinet, and the input end of the third current transformer is connected to the auxiliary wiring of the asynchronous motor box, the input end of the third current transformer is connected to the input end of the arrester, and the output end of the arrester is grounded.