RU199073U1 - VOLTAGE TRANSFORMER - Google Patents

Abstract

The utility model relates to the field of electrical engineering and can be used to implement the soft start of asynchronous, synchronous drive motors as part of an electric drive of general industrial design of fans, smoke exhausters, pumps and other mechanisms. The device includes high-voltage thyristor units (HVT) for phase voltage regulation, current sensor , voltage sensors at the input and output of the voltage converter, mains and bypass contactors, overvoltage limiters at the output of the device in each phase, a synchronization voltage source, a pulse-phase control unit (PIFU), the enabling input of the PIFU is connected to one of the outputs of the control unit, pulse amplifiers with a generator of high-frequency pulses, pulse transformers connected to the control electrodes of thyristors, a monitoring unit, diagnostics of the state of the engine and mechanism, a control unit including protection, interlocking, signaling modules, an automatic control unit consisting of from the intensity generator (ZI), voltage regulator (RN), current regulator (RT), the output of the current regulator (RT) is connected to the control input of the BIFU; the automatic control unit is additionally equipped with a voltage setting module, a current setting module, a current limiting module, moreover, a reference for the initial voltage and a reference for the motor voltage are sent from the control unit to the engine voltage setting unit, the output of the motor voltage setting module is connected to the input of the ramp generator, the output of which is connected to the input of the voltage setting module and to the input of the voltage regulator (RN), and the given initial voltage at the output of the ramp generator changes with a forced slew rate, the output of the voltage regulator (RN) is connected to one of the inputs of the motor current setting, the other input of the current setting module is connected with one of the outputs of the control unit, which sets the initial motor current, the output of the motor current setting module is connected to the input of the current limiting module, the output of the current limiting module is connected to one of the inputs of the current regulator (PT), one of the outputs of the control unit is connected to the enabling inputs The technical result achieved from the use of the device is to reduce additional losses, reduce vibration, noise in the engine before starting it, increase the reliability of the electric drive, ensure the specified parameters of soft start, and their stabilization. 4 h. p. f-ly, 3 ill.

Description

The utility model relates to the field of electrical engineering and can be used to implement smooth start-up of high-voltage asynchronous, synchronous drive motors as part of an electric drive of general industrial design of drives for fans, smoke exhausters, pumps and other mechanisms with severe starting conditions.

Voltage converters (PN) for soft start of asynchronous, synchronous drive motors are made for different powers for starting high-voltage and low-voltage motors.

There is a device (patent RU 124088, 07/03/2012 Н02Р 1/26, Н02Р 1/28) containing thyristor switch units for phase voltages, a system for pulse-phase control of thyristors of switches, a command unit, the output of which is connected to the enable input of the pulse-phase control system , a block for setting the current (setting current), a current meter and a current regulator, one input of which is connected to the output of the setting block, the second to the output of the meter, and the output is connected to the control input of the pulse-phase control system.

The disadvantages of the analogue are the presence of a current surge at start-up, which instantly increases to the level of the current limitation (setting) and remains at this level, the output voltage is not controlled and is formed from the condition of ensuring a steady current, while for some time (up to several seconds) to overvoltage may be applied to the motor winding.

Known three-phase device (patent RU 55227, 26.12.2005 Н02Р 5/00), used for the soft start of asynchronous motors. The device contains the following elements, similar to the set of essential features of the proposed utility model: thyristor switch units of phase voltages, connected along the input circuit with the phases of the supply network through current transformers and along the output circuit with a load, a synchronization voltage source, channels for pulse-phase control of switch thyristors, pulse amplifiers with a high-frequency pulse generator, pulse transformers connected to the control circuits of thyristor control units. We select this device as a prototype, as the closest to the proposed device in technical essence.

The disadvantage of the prototype is additional losses, vibrations, noise in the engine associated with higher harmonics of voltage and current with a linear voltage rise until the start of the engine; uncontrolled voltage rise on the motor winding.

The task of the utility model is to increase the reliability of the electric drive equipment, stabilize the start-up parameters, ensure that the drive motor starts smoothly from a current level sufficient to create a starting torque for starting the motor without stopping it under a slowly increasing voltage that creates insufficient motor torques, as well as for continuation of acceleration according to the linear law of voltage rise when the starting current is limited, in order to exclude additional higher harmonics when starting the motor, which create losses, vibration, noise in the motor, as well as uncontrolled increase and increase in voltage in the motor winding.

The specified technical problem is solved as follows: a well-known voltage converter (PN) device for smooth starting of electric motors (EM), containing high-voltage thyristor units (HVT) for phase voltage regulation, a current sensor, voltage sensors at the input and output of the converter, network and bypass contactors, surge suppressors at the output of the device in each phase, a synchronization voltage source, a pulse-phase control unit (PIFU) for thyristors of switches, pulse amplifiers with a high-frequency pulse generator, pulse transformers connected to the control circuits of thyristor control units, a control unit containing command systems, protection , locks, alarms; an automatic control system unit, which is additionally equipped with a voltage setting module (MZN), a current setting module (MZT), a current limiting module (MOT), and from the control unit to the engine voltage setting unit, a reference for the initial voltage, a reference for motor voltage, output the motor voltage setting module is connected to the ramp generator input, the ramp generator output is connected to one of the inputs of the voltage setting module and to the voltage regulator (PH) input, the voltage regulator (PH) output is connected to one of the inputs of the motor current setting module, its other input is connected to the output of the control unit, which sets the initial starting current of the engine, the output of the motor current setting module is connected to the motor current limiting module, the output of the current limiting module is connected to one of the inputs of the current regulator (RT), the output of which is connected to the control input of the CIFU, allowing the CIFU input connected to the output of the control unit, one of the outputs of the control unit It is connected to the permissive inputs of the modules of the intensity generator (RG), voltage regulator (RN), current regulator (RT).

FIG. 1, fig. 2, fig. 3 shows a block diagram of a voltage converter as part of an electric drive for smooth start-up of high-voltage electric motors.

The voltage converter contains: 1, 2 current transformers (TA1..TA3); current sensor 3 (DT1); voltage control module 4; mains voltage sensor 5 (DN1); vacuum contactors 6.7 (KM1, KM2); 8 thyristor high-voltage units in each phase (U1..U3); voltage limiters 9 (FV1..FV3); sensor 10 of the output voltage of the voltage converter (DN2); control unit 11 (BU); module 12 voltage setting (MZN - comparison element); set device 13 intensity (ZI); voltage regulator 14 (RN); module 15 setting the current (MZT - comparison element); module 16 current limiting (ILO); current regulator 17 (RT); block 18 pulse-phase control (BIFU); block 19 of the formation of pulses (BFI) control thyristors. In the circuit of the setpoint 13 intensity (ZI), voltage regulator 14 (RN), current regulator 17 (RT) included shunt keys, respectively K1, K2, K3, which in the initial state are closed and opened by an enable signal from the control unit 11. If there are 20 temperature and vibration sensors in the drive engine, a monitoring and diagnostics unit 21 (BMD) can be included in the control system of the converter. FIG. 2 shows a block diagram of a voltage converter with a module 22 for setting the control angle (MCU). FIG. 3 shows a block diagram of a voltage converter with a network voltage drop regulator 23 (RPNS). Thyristor high-voltage units are connected between the electric motor 20 and the "network" 24 with a switch 25 VRU-6, 10 kV.

The device operates as part of an electric drive as follows. In the initial state, all power switching devices are disconnected, supply voltages are supplied to auxiliary devices and the control system of the PN. The control unit 11 receives signals: about the state of switching devices (switch 25 (Q1) in RU-6, 10 kV, vacuum contactors 6, 7 (KM1, KM2)); on the state of the supply network voltages from the voltage control module 4 (MCN); signal about the value of the current from the current transformers 1,2 through the converter of the current sensor 3 (DT1).

The inputs of the control unit 11 also receive commands: "Start", "Stop", "Reset", "Emergency shutdown", "Emergency".

One of the outputs of the control unit 11 is connected to the enable input of the BIFU 18, one of the outputs of the control unit 11 is connected to the enable inputs of the intensity setpoint 13 (key K1), voltage regulator 14 (key K2), current regulator 17 (short-circuit key); the outputs of the control unit 11 are connected to the inputs of the voltage setting module 12 (MZN) and to the current setting module 15 (MZT); the output of the current sensor 3 (DT1) is connected to the control unit 11 (CU) and to one of the inputs of the current regulator 17 module (RT).

In the initial state of the PN, the control unit 11 blocks the control pulses in the BIFU 18 (thyristors in the BTV are closed), the K1 key in the intensity setter 13, the K2 key in the voltage regulator 14, the short circuit key in the current regulator 17 are closed. In the voltage setting module 12 (MZN) (for example, the KN1 key in MZN 12 is disabled), the circuit for transmitting the voltage setting (W *) to the engine is blocked.

After turning on the mains switch 25 (Q1), the control unit PN receives signals: about turning on the switch 25, about the state of the mains voltage (voltage is "normal") from the voltage control module 4 (MCN). When these signals are received, the control unit 11 generates a signal that the PN is ready for operation ("PN READY"), which allows turning on the line contactor 6 (KM1).

At the command "START" control unit 11:

switches on with a time delay the mains contactor 6 (KM1), which supplies the mains voltage to the thyristor high-voltage units 8 (U1..U3);

sends a signal to the IFC 18 for permission (removes the signal "BIU") the passage of thyristor control pulses;

disables keys K1, K2, K3 (shuts down) ZI 13, RN 14, RT 17;

to the inputs of the voltage setting module 12, reference signals for the initial voltage (U0 *) and for the motor voltage (UZ *) are transmitted;

to one of the inputs of the module 15 for setting the current (MCT), which is made in the form of a comparison element, transmits the task for the starting current 10 * of the motor.

The reference for the starting current 10 * of the motor through the module 15 of the current setting (since the signal IZ * from the output of the voltage regulator 14 (PH) is less than 10 *), through the module 16 of the current limiting (MOT) it is fed to one of the inputs of the current regulator 17 (RT) , the other input receives a current feedback signal 1os from the current sensor 3 (DT1). The signal from the output of the current regulator 17 (RT) is fed to the control input of the BIFU 18; BIFU 18 generates control pulses through six channels, which are amplified by the pulse shaping unit 19 (BFI) and transmitted through galvanic isolators to the control electrodes of the thyristors, the converter, in accordance with the task, generates a starting current of the motor in the motor winding 20 (Ml), the shaft of which begins to rotate immediately and slowly pick up the speed.

Simultaneously with the supply of starting current 10 to the motor winding, the voltage setting module 12 (MZN) transmits the task for the initial voltage U0 * from the input to the output of the module, since the voltage setting circuit from * is blocked (for example, the KN1 key in the MZN 12 is disabled) and transmits this is the task at the input of the ZI 13. The signal UZV * from the output of the ZI 13 is transmitted to one of the inputs of the voltage setting module 12 (MZN) and to the input of the voltage regulator 14 (RN), to the other input of the RN 14 a feedback signal on the output voltage Uoc sensor 10 (DN2). While the output signal IZ * from the voltage regulator 14 (PH) is less than or equal to the reference for the initial motor current 10 * to the input of the current regulator 17 (PT) through the MZT 15 modules, the ILO 16 receives a reference signal only for the starting current 10 *.

The intensity generator 13 is executed with variable parameters of the increase in the output signal, determined by the value of the specified voltage and the operating mode (soft start, braking).

The output signal (current (instant) value of the reference for the voltage UZV * of the engine ZI 13 is formed in accordance with the formulas:

where: T0 is the given rise time of the task for the initial voltage;

TP - set time of soft start;

t _i - current time.

At the output of ZI 13, a signal is generated with a high degree of increase in the voltage reference, determined by the value of the reference for the initial voltage U0 * and the time of its rise TO, when the voltage at the output of the ZI 13 UZV * becomes greater than the reference for the initial voltage U0 *, in the voltage setting module 12 ( MZN), the comparator DA1 will work and turn on the KN1 switch, since the voltage setting W * is greater in magnitude of the task for the initial voltage U0 *, the voltage at the output of the diode VD1 will close the diode VD2 and from the output of the voltage setting module 12 at the input of ZI 13 the task W * will be sent to motor voltage, at the output of ZI 13, a signal of the current reference UZV * is generated for the motor voltage with a rate of rise corresponding to the time of the motor soft start.

The voltage reference signal UZV * ED 20 from the ZI 13 output is fed to one of the inputs of the RN 14 voltage regulator, and the voltage feedback signal Uoc is fed to the other input. The output voltage regulator 14 generates a signal (IZ *) for setting the current of the stator winding ED 20, which is fed to one of the inputs of the module 15 for setting the current (MCT). While the output signal from the voltage regulator 14 (PH) is less than or equal to the reference for the initial motor current 10 * to the input of the current regulator 17 (PT) through the MZT 15 modules, the ILO 16 receives the starting current 10 * reference signal when the signal (IZ *) at the output of PH 14, the starting current 10 * of the motor will be greater, in the current setting module 15 (MZT) the voltage on the VD3 diode will be higher than the voltage on the VD4 diode, the VD4 diode will close and the current setting signal IZS is sent to the output of the current setting module 15 * equal to the current IZ * from the output PH 14, which is fed through the module 16 of the current limiting (MOT) to one of the inputs of the current regulator 17 (PT), if the signal value is less than or equal to the specified value of the current limiting Ip *, if it is greater, the current setting limited by the set value of the starting current Ip *. The other input of the current regulator 17 (PT) receives a current feedback signal Ioc from the current sensor 3 (DT1); the signal U _αi *, which is the task for the control angle of the thyristors α *, from the output of the current controller 17 RT is fed to the control input of the BIFU 18; BIFU 18 generates control pulses along six channels, which are amplified by the pulse shaping unit 19 (BFI) and transmitted through galvanic isolation to the control electrodes of the thyristors, the converter, in accordance with the current assignment, forms a soft start current of the motor in the motor winding 20 (M1), the shaft of which begins to increase the speed in accordance with the signal of the current reference IZS * generated by the voltage regulator 14 (PH). The control pulses generated in the IFC 18 are limited to the minimum and maximum permissible control angle (αmin and αmax).

With a successful soft start of the drive motor from the LV and reaching the specified voltage on the winding and current in the motor, the control unit 11 generates a command to turn on the KM2 bypass contactor for a single electric drive, the motor 20 (Ml) switches to direct power from the "network" 24, while the unit 11 control monitors the current, voltage and other parameters of the motor, if the motor is equipped with appropriate sensors.

For the "cascade" electric drive, a command is generated to turn on the 25 AQc mains switch in the 6 kV switchgear of the started ED and turn off the corresponding boost switch Qp of the regulated voltage bus section (SSRN).

Thus, the automatic control system controls the effective voltage and current of the drive motor.

The motor starts smoothly immediately after the start command with starting current, gradually increasing the speed with limiting the starting current. The voltage across the stratum winding of the motor increases from a given initial voltage to a given voltage equal to the rated value of the motor for a given starting time.

In case of an unsuccessful start of the drive motor from the PN for a given start-up time, the control unit 11 generates an "EMERGENCY" command, according to which the thyristor control pulses are blocked (the "BIU" signal is generated and transmitted to the BIFU 18), ZI 13, RN 14, RT 17 are blocked, contactor 6 (KM1) is turned off and the electric drive circuit is disassembled.

FIG. 2 shows a block diagram of a voltage converter for soft start of high-voltage electric motors with parallel connection of the current regulator 17 and the voltage regulator 14.

The channel for setting the voltage in the block diagram of the voltage converter shown in Fig. 2 operates in the same way as FIG. 1. Only the voltage regulator 14 (RN) at the output generates a signal (αu *) for setting the angle of control of thyristors, which is fed to one of the inputs of the module 22 for setting the control angle (MCU). The other input of the control angle setting unit 22 is supplied with a signal (αi *) from the output of the current controller 17 (PT). In the module 22 for setting the control angle, both of these signals are compared and at the output, a command for the control angle of the thyristors (α *) is generated, the signal of which corresponds to a larger control angle of the thyristors αu * or αi *. The signal from the output of the module 22 setting the control angle is fed to the pulse-phase control unit 18 (PIFU).

Reference signals for the starting current (I0 *), starting current (Iп *) to the input of the current regulator 17 (PT) are supplied from the control unit 11, and the starting current reference (In *) is supplied with a time delay after the starting current reference is removed ( I0 *). Thus, the current and voltage on the winding of the starting motor are set simultaneously, while the leading regulator is the one at the output of which the task for a larger thyristor control angle is formed, which increases the stability and reliability of the control system.

FIG. 3 shows a block diagram of a voltage converter for smooth start-up of high-voltage electric motors with a network voltage drop regulator 23 (RPNS).

The main control channels of the voltage converter for soft start of drive motors with a structural diagram according to FIG. 3 are similar to the control channels with block diagrams of FIG. 1 and FIG. 2. The block of the automatic control system of the voltage converter shown in FIG. 3 is additionally equipped with a network voltage drop regulator 23 (RPNS), the inputs of which are connected to the network voltage sensor 5 (DN1) and to the control unit 11, and its output is connected to one of the inputs of the current limiting module 16 (MOT) for the structure of FIG. 1 or with one of the inputs of the current regulator 17 for structure 2. The admissible value of the setpoint (Uc *) of the mains voltage and the feedback of the mains voltage (Uc-oc) from the sensor 5 are fed to the input of the regulator 23 of the mains voltage drop (RPNS) from the control unit 11 voltage (DN1). If during soft start the value of the mains voltage setpoint (Uc *) is less than the mains voltage Uc, the signal is not generated at the output of RPNS 23, but if the value of the mains voltage setpoint (Uc *) is greater than the mains voltage Uc, then a signal proportional to the inadmissible voltage drop in the supply network. The signal from the output of the RPNS 23 is fed to the input of the current limiting module (MOT) 16 for the structure in FIG. 1 or to one of the inputs of the current regulator (PT) 17 for the structure of FIG. 2, decreasing the set value of the starting current limitation, which reduces the voltage drop in the network to the set level.

The operational stop of the PN is carried out by pressing the "Stop" button.

In the event of emergency situations, the control unit 11 generates signals to turn off the voltage converter.

The subsystem of protections and interlocks provides the mode of normal shutdown of the PN when the following protections are triggered:

from overvoltage and unacceptable voltage reduction at the input and output of the PN, incorrect phase sequence; from an unacceptable increase in voltage at the PN output to 1.2U _cm ; from lowering the voltage of the power network to 0.8 * U _H with a time delay from 0.05 to 2.5 s; from an unacceptable decrease in the supply voltage for auxiliaries below 0.8 * U _N-SN (by a signal from MKN 4).

from an increase in the current at the input (output) PN above the permissible value (I _p > K _p * I _n );

for integral current protection I ² 1t - thermal protection against inadmissibly prolonged overcurrent;

from opening the doors of the power section (cabinet) PN;

by signal "EMERGENCY".

The protection subsystem of the control unit 11 disables the converter through two channels: grid disconnection (the “BIU” signal closes the LV thyristors); disconnecting the supply voltage of the PN by generating a signal to disconnect the contactors 6, 7 (KM1, KM2).

The protection system of a high-voltage voltage converter provides voltage removal from the output circuit of the converter, from the drive motor (from the section of regulated voltage buses), and also acts on disconnecting contactors (switch in the supply connection RU-6 kV).

Claims (5)

1. Voltage converter for smooth start-up of drive asynchronous, synchronous motors, containing high-voltage thyristor units (HVT) for phase voltage regulation, consisting of two high-voltage modules, the thyristors of which in each module are connected in series, and the modules themselves are connected in anti-parallel, to each thyristor connected RC-circuit, current sensor, voltage sensors at the input and output of the voltage converter, mains and bypass contactors, surge suppressors at the output of the device in each phase, a synchronization voltage source, a pulse-phase control unit (PIFU), the enable input of the PIFU is connected to one from the outputs of the control unit, pulse amplifiers with a high-frequency pulse generator, pulse transformers connected to the control electrodes of thyristors, a monitoring unit, diagnostics of the state of the engine and mechanism, a control unit including protection, interlocking, signaling modules, an automatic control system unit control, consisting of an intensity generator (ZI), a voltage regulator (RN), a current regulator (RT), the output of the current regulator (RT) is connected to the control input of the BIFU, characterized in that the automatic control system unit is equipped with a voltage setting module, a current setting module , by the current limiting module, and from the control unit to the motor voltage setting unit, the reference for the initial voltage and the reference for the motor voltage are supplied, the output of the motor voltage setting module is connected to the input of the ramp generator, the output of which is connected to the input of the voltage setting module and to the input of the voltage regulator ( PH), and the given initial voltage at the output of the ramp generator changes with a forced slew rate, the output of the voltage regulator (PH) is connected to one of the inputs of the motor current setting module, the other input of the current setting module is connected to one of the outputs of the control unit, which sets the initial motor current, motor current setting module output is connected to the input of the current limiting module, the output of the current limiting module is connected to one of the inputs of the current regulator (PT), one of the outputs of the control unit is connected to the enabling inputs of the ramp generator, voltage regulator, current regulator. 2. The voltage converter according to claim 1, characterized in that the automatic control system unit is equipped with a control angle setting module (MCU) with thyristors, the inputs of which are connected to the output of the voltage regulator (PH) and to the output of the current regulator, the output signal of the MCU is calculated from the maximum control angle of thyristors, the output of the MZUU is connected to the control input of the BIFU, and the reference for the starting current and the starting current in the current regulator (RT) comes from the control unit. 3. Voltage converter pop. 1 or 2, characterized in that the automatic control system unit is equipped with a mains voltage drop regulator (RPNS), the inputs of which are connected to the mains voltage sensor (DN1) and to the control unit, and its output is connected to one of the inputs of the current limiting module (Fig. 1 ) or with one of the inputs of the current regulator (Fig. 2). 4. The voltage converter according to claim 1, characterized in that the galvanic isolation of the transmission of control pulses is made in the form of a transmitter, a receiver of optical signals connected by optical cables, and the control system is equipped with a device for automatic synchronization of thyristor control pulses, which matches the control angles of each phase with the corresponding voltage. phases of the supply voltage. 5. Voltage converter according to claim 1, characterized in that the control system blocks of the converter are hardware-made in the form of microprocessor devices based on a touch panel, a controller with power modules, a central processor, input-output modules for discrete and analog signals, and control algorithms, automatic regulation, protection, blocking, signaling, messages are implemented in software.

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