CN214626369U - Voltage reduction compensation soft starting device - Google Patents
Voltage reduction compensation soft starting device Download PDFInfo
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- CN214626369U CN214626369U CN202023311880.4U CN202023311880U CN214626369U CN 214626369 U CN214626369 U CN 214626369U CN 202023311880 U CN202023311880 U CN 202023311880U CN 214626369 U CN214626369 U CN 214626369U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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Abstract
The utility model relates to a step-down compensation soft starting device, the input end of which is connected into the power grid through a starting cabinet, the output end of which is connected with a to-be-started motor through a wire outlet cabinet, the to-be-started motor is also connected into the power grid through an operation cabinet, the soft starting device comprises a transformer, an adjustable resistor and a high-voltage capacitor, the primary side of the transformer is connected with the output end of the starting cabinet, and the primary side neutral point of the transformer is connected with the adjustable resistor through a neutral point switch and then is connected into a star shape; the secondary side of the transformer is connected with the input end of the outgoing line cabinet, the secondary side of the transformer is connected with the high-voltage capacitor through a starting fling-cut switch and then is connected into a star shape, and the high-voltage end of the high-voltage capacitor is connected with the primary side of the transformer through an operation fling-cut switch. The utility model discloses can improve the power factor among the starting process to the high-voltage capacitor who uses as the reactive power compensation usefulness on the spot, improved equipment utilization, practiced thrift the cost.
Description
Technical Field
The utility model relates to a motor starts technical field, concretely relates to soft starting drive of step-down compensation.
Background
For a high-power high-voltage motor (such as a 10000-35000 kW/10kV motor), except a frequency converter, the starting current of the motor can be reduced in the conventional high-voltage soft start product on the market at present, but the problem of low power factor in the starting process still exists. The power factor of the power grid is an important index, and also concerns the energy conservation and the stability of the power grid, and particularly the starting of a large-capacity motor brings great influence to the system. And normally, the soft start equipment is separated from the power grid after being started, and a large amount of high-voltage capacitors for providing reactive compensation for the motor are unused in the starting process, so that certain resource waste is caused.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to the technical problem who exists among the prior art, provide a soft starting drive of step-down compensation, its adjustable power factor, and start the high-voltage capacitor who uses after accomplishing and use as reactive compensation on the spot, improved rate of equipment utilization, practiced thrift the cost.
The utility model provides an above-mentioned technical problem's technical scheme as follows:
the input end of the soft starting device is connected to a power grid through a starting cabinet, the output end of the soft starting device is connected to a motor to be started through an outgoing line cabinet, the motor to be started is also connected to the power grid through an operation cabinet, the soft starting device comprises a transformer, an adjustable resistor and a high-voltage capacitor, a primary side of the transformer is connected to the output end of the starting cabinet, and a primary side neutral point of the transformer is connected to the adjustable resistor through a neutral point switch and then connected into a star shape; the secondary side of the transformer is connected with the input end of the outgoing line cabinet, the secondary side of the transformer is connected with the high-voltage capacitor through a starting fling-cut switch and then is connected into a star shape, and the high-voltage end of the high-voltage capacitor is connected with the primary side of the transformer through an operation fling-cut switch.
Further, electric switches are arranged in the starting cabinet, the outgoing line cabinet and the operation cabinet, and the electric switches, the neutral point switch, the starting fling-cut switch and the operation fling-cut switch are all provided with electric actuating mechanisms.
The device further comprises a control system, wherein the control system is respectively in signal connection with the starting cabinet, the neutral point switch, the outgoing line cabinet, the running cabinet, the starting fling-cut switch and the running fling-cut switch and is used for controlling fling-cut of the starting cabinet, the neutral point switch, the outgoing line cabinet, the running cabinet, the starting fling-cut switch and the running fling-cut switch.
Further, the control system is in signal connection with the adjustable resistor and is used for adjusting the resistance value of the adjustable resistor.
Further, the control system is a PLC.
Further, the device also comprises a touch screen which is in communication connection with the control system.
The utility model has the advantages that: a variable resistance device is added on the neutral point side of the transformer, so that the bus power factor in the starting process is improved, and the voltage drop of a power grid is reduced; after the motor is started, the high-voltage capacitor for starting is switched by the operation switching switch, so that the high-voltage capacitor is used for on-site reactive compensation, the equipment utilization rate is improved, a user can not purchase necessary on-site compensation equipment again, and the cost is saved.
Drawings
FIG. 1 is a schematic structural diagram of a conventional buck compensation soft start device;
FIG. 2 is a diagram of a conventional buck-compensated soft-start equivalent circuit and its vector diagram;
fig. 3 is a schematic diagram of the circuit structure of the present invention.
Detailed Description
The principles and features of the present invention are described below in conjunction with the following drawings, the examples given are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.
Fig. 1 shows a step-down compensation soft start device in the prior art, which includes a transformer, a neutral point control cabinet, a high-voltage capacitor, and a capacitance control cabinet connected to each other, wherein a primary side of the transformer is connected to a power grid through the start cabinet, a primary side of the transformer is connected in a star shape through the neutral point control cabinet, and a secondary side of the transformer is connected to a motor to be started through an outlet cabinet; the high-voltage capacitor is connected to the secondary side of the transformer through the capacitance control cabinet; the motor to be started is also connected to a power grid through the operation cabinet;
the transformer is used for reducing the voltage connected into the motor and increasing the current flowing into the motor;
the neutral point control cabinet is used for controlling the switching of the transformer;
the high-voltage capacitor is used for providing reactive compensation for the starting process of the motor;
the capacitance control cabinet is used for controlling the switching of the high-voltage capacitor;
the starting cabinet is used for controlling the device to be connected into a power grid;
the outgoing line cabinet is used for controlling the device to be connected with the motor;
the operation cabinet is used for controlling the motor to be connected into a power grid.
Electric switches are arranged in the capacitance control cabinet, the neutral point control cabinet, the starting cabinet, the outgoing line cabinet and the running cabinet, and the electric switches are provided with electric actuating mechanisms. The electric switch connected with the high-voltage capacitor in the capacitance control cabinet is a circuit breaker.
The capacitance control cabinet is further provided with a PLC and a touch screen, and the PLC is in signal connection with the neutral point control cabinet, the starting cabinet, the outgoing line cabinet and the electric switch in the operation cabinet respectively. The touch screen is in communication connection with the PLC, and the touch screen provides man-machine interaction. The PLC is used as a control unit of the device, converts a control command input by an operator on a touch screen into a control signal, and outputs the control signal to control the switching on and off of each electric switch in the capacitance control cabinet, the neutral point control cabinet, the starting cabinet, the outgoing line cabinet and the running cabinet, so that the control on the starting process of the motor is realized.
The soft starting device for the voltage reduction compensation is suitable for large and medium high-voltage squirrel-cage alternating current asynchronous motors or high-voltage synchronous motors which are asynchronously started, and is used for starting the motors in a voltage reduction mode. The soft starter is widely used for the voltage reduction soft start of a motor with the voltage grade of 6kV to 10kV, the power range of 2000kW to 50000kW and even higher power. The soft start device has the soft start characteristics of small and constant starting current and gradually increased torque, has small influence on a power grid during starting, is little influenced by temperature change, has no electromagnetic interference, is an ideal substitute product for various reactors and resistors for voltage reduction starting, and has the advantages of obvious simplicity in operation, no maintenance, no harmonic pollution and the like compared with a high-voltage variable-frequency soft starter.
Fig. 2 is an equivalent circuit diagram and a vector diagram of a primary system of the buck compensation soft start device. The power factor of the motor is very low in the starting process, and the cos phi is usually 0.1-0.2, so that the motor consumes a large amount of reactive power of a power grid in the starting process, and the starting current is usually 6-7 times of the rated current of the motor when the motor is directly started. As can be seen from the equivalent circuit diagram of fig. 2, the starting current I consumed in starting the motor if a suitable reactive power can be provided at the motor end2It is significantly reduced. In order to further reduce the bus side current I1The parallel loop of the motor and the high-voltage capacitor is connected into a power grid through a transformer, and the bus current I can be further reduced by reducing the terminal voltage1The circuit structure shown in fig. 1 is formed.
The whole starting process of the voltage reduction compensation soft starting device is described as follows:
(1) a PLC detection capacitor control cabinet, a neutral point control cabinet, a starting cabinet, an outgoing line cabinet and an operating cabinet in the capacitor control cabinet are all prepared, and a touch screen displays 'starting permission';
(2) starting operation is carried out beside (or in a central control mode) the slave computer, a starting instruction is sent to a PLC in the capacitance control cabinet, the PLC automatically closes the capacitance control cabinet, the neutral point control cabinet and the outgoing line cabinet, and the starting cabinet is closed in a delayed one second mode; after the starting cabinet is switched on, the motor starts, and the touch screen displays that the motor is started;
(3) when the voltage of the motor terminal reaches a voltage protection set value of the high-voltage capacitor, the PLC opens and closes a 1# circuit breaker in the capacitor control cabinet, and the high-voltage capacitor of the first loop is cut off;
(4) when the voltage of the motor terminal reaches a voltage protection set value of a high-voltage capacitor of a second loop, the PLC opens and closes the 2# circuit breaker in the capacitor control cabinet, and high-voltage capacitors of the second loop are cut off (for motors with different capacities, high-voltage capacitors with different loop numbers can be selected);
(5) when the PLC detects that the current of the motor is reduced below the rated current of the motor (or the synchronous machine is started, the PLC is used for detecting the current of the motor and then sending a 'full voltage signal' to the PLC), and the PLC breaks a neutral point circuit breaker in a neutral point control cabinet; then closing the operation cabinet, and operating the motor under rated voltage; the motor is not powered off in the whole process of switching full voltage, so that the problem of secondary current impact when full voltage is applied is avoided;
(6) after the operation cabinet is switched on, the PLC subsequently switches off the starting cabinet and the wire outlet cabinet, the voltage reduction compensation soft starting device is disconnected with the high-voltage power grid, and starting is completed.
In the above scheme, the transformer functions as follows:
(1) the side voltage U of the 10kV bus1Reducing the pressure to U2Then the voltage is applied to the motor end to reduce the starting current of the motor;
(2) the side current I of the 10kV bus1Amplification to I2The power supply is added at the motor end to reduce the requirement of starting on the current of a bus-side power grid;
(3) the motor can not lose power when the motor is switched to full voltage at the later stage of starting, the terminal voltage is ensured to be consistent with the voltage angle of the bus, the secondary current impact of a power grid when the motor is switched to full voltage is eliminated, and the ideal full voltage switching effect is achieved.
The function of the high-voltage capacitor is:
the reactive current of the motor is greatly needed when the motor is started, and the requirement of the motor on the reactive current of the bus side when the motor is started is further reduced.
The function of the capacitance control cabinet is as follows:
(1) the power supply circuit is matched with a high-voltage capacitor to timely supply and cut off reasonable reactive power;
(2) the device is provided with a PLC and a touch screen as a control system of the device.
The function of the neutral point control cabinet is as follows:
(1) providing proper motor terminal voltage by matching with a transformer;
(2) and when the starting is in the later stage, the operation overvoltage during switching full voltage is eliminated.
However, for a high-power high-voltage motor (such as 10000-35000 kW/10kV motor), except for a frequency converter, the conventional high-voltage soft start product on the market at present can reduce the starting current of the motor, but still has the problem of low power factor in the starting process. The power factor of the power grid is an important index, and also concerns the energy conservation and the stability of the power grid, and particularly the starting of a large-capacity motor brings great influence to the system.
Therefore, the technical scheme of the embodiment is provided for improving the equipment of the starting mode of 'voltage reduction + compensation' so as to improve the power factor in the starting process and achieve the effect of stabilizing the power grid.
The specific scheme of this embodiment is shown with reference to the schematic circuit structure diagram of fig. 3.
According to the voltage reduction compensation soft starting device provided by the embodiment, the input end of the voltage reduction compensation soft starting device is connected to a power grid through a starting cabinet, the output end of the voltage reduction compensation soft starting device is connected with a motor to be started through an outgoing line cabinet, and the motor to be started is also connected to the power grid through an operation cabinet. The voltage-reducing compensation soft starting device comprises a transformer, an adjustable resistor and a high-voltage capacitor, wherein the primary side of the transformer is connected with the output end of a starting cabinet and is connected to a power grid through the starting cabinet. The neutral point on the primary side of the transformer is connected with the adjustable resistor through the neutral point switch and then connected into a star shape, when the neutral point switch is switched on, the primary side of the transformer is connected with the adjustable resistor, and the power factor of the motor during starting can be adjusted by changing the resistance value of the adjustable resistor. The secondary side of the transformer is connected with the input end of the outgoing line cabinet, and the switching of the outgoing line cabinet is controlled to control the on-off of the soft starting device and the motor to be started. The secondary side of the transformer is connected with the high-voltage capacitor through a starting switching switch and then connected into a star shape, when the switching switch is switched on and started in the starting process of the motor, the high-voltage capacitor can be connected into a circuit, and at the moment, the high-voltage capacitor provides reactive compensation for the starting of the motor. The high-voltage end of the high-voltage capacitor is also connected with the primary side of the transformer through the operation fling-cut switch, when the motor is started, the fling-cut switch can be switched on to operate and switched off to start the fling-cut switch, and at the moment, the high-voltage capacitor for starting is equivalently changed into the high-voltage capacitor for local reactive compensation, so that the utilization rate of equipment is improved.
In this embodiment, electric switches are disposed in the starting cabinet, the outgoing line cabinet and the operating cabinet, and the electric switches, the neutral point switch, the starting fling-cut switch and the operating fling-cut switch are all provided with electric actuating mechanisms. When the electric actuating mechanism receives a switching-on or breaking signal, the electric actuating mechanism realizes switching-on or breaking actions of all the switches.
In this embodiment, the device further includes a control system, and the control system is respectively in signal connection with the starting cabinet, the neutral point switch, the outgoing line cabinet, the operating cabinet, the starting fling-cut switch, and the operating fling-cut switch, and is configured to control fling-cut of the starting cabinet, the neutral point switch, the outgoing line cabinet, the operating cabinet, the starting fling-cut switch, and the operating fling-cut switch.
In this embodiment, the control system is in signal connection with the adjustable resistor, and is configured to adjust a resistance value of the adjustable resistor.
In this embodiment, the control system is a PLC.
In this embodiment, the apparatus further includes a touch screen, and the touch screen is in communication connection with the control system. When an operator inputs a control instruction on the touch screen or a central control system connected with the device, the PLC converts the control instruction into a corresponding control signal to be output so as to realize the operation of soft starting of the motor.
The utility model discloses a theory of operation:
as shown in fig. 3, an operator operates on the touch screen, firstly controls a switch-on starting cabinet, a neutral point switch, a starting switching switch, an outgoing line cabinet and a switch-off operating cabinet through a PLC, reduces a 10kV grid high voltage to a starting voltage (for example, 7.5kV) through a transformer, and connects an adjustable resistance device in series to a primary side neutral point side of the transformer to adjust a power factor when a motor is started; a high-voltage capacitor is connected in parallel with the secondary side of the transformer to compensate the reactive power requirement of the motor in the starting process. And after the motor is started to the later stage and the rotating speed of the motor is increased, the switching switch is started by stage brake separation to cut off the high-voltage compensation capacitor, and then the neutral point switch is cut off to further improve the voltage of the motor terminal. When the rotating speed of the motor is close to the rated rotating speed, the operating cabinet is switched on, the motor operates in full pressure, and then the starting cabinet and the wire outlet cabinet are switched off.
The power factor in the starting process can be improved by adding a variable resistance device on the neutral point side of the transformer based on the improvement of the conventional voltage reduction and compensation soft starting device. The principle is as follows: a variable resistance device is added on the neutral point side of the transformer, and the equivalent resistance r of the primary winding is known from a T-shaped equivalent circuit of the transformer1Much smaller than the equivalent leakage reactance x of the primary winding1If a variable pure resistance device is added to the neutral point of the transformer, the total impedance (r) of the primary winding is correspondingly increased without considering the influence of the secondary side and the load of the transformer1+rVariable) In the transformer equivalent reactance Z1(i.e. Z)1＝(r1+rVariable)+jx1) The ratio value of the transformer is increased, the access power factor of the transformer is increased, the bus power factor in the starting process is correspondingly increased, and the voltage drop of a power grid is reduced.
Normally, after the soft start equipment is started, the soft start equipment is separated from a power grid, and a large number of high-voltage capacitors are unused, so that certain resource waste is caused. Therefore, an operation switching switch is additionally arranged between the high-voltage capacitor and the starting cabinet, and the PLC program logic is modified, so that the control system only cuts off the outgoing line cabinet after the starting is finished, and the starting cabinet does not cut off. At the moment, the operation switching switch can be switched on at any time according to the power factor of the power grid, the high-voltage capacitor for starting is changed into the high-voltage capacitor for local reactive compensation, and the utilization rate of equipment is improved. The user can not buy necessary local compensation equipment again, so that the cost is saved.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.
Claims (6)
1. The input end of the soft starting device is connected to a power grid through a starting cabinet, the output end of the soft starting device is connected to a motor to be started through an outgoing line cabinet, and the motor to be started is also connected to the power grid through an operation cabinet; the secondary side of the transformer is connected with the input end of the outgoing line cabinet, the secondary side of the transformer is connected with the high-voltage capacitor through a starting fling-cut switch and then is connected into a star shape, and the high-voltage end of the high-voltage capacitor is connected with the primary side of the transformer through an operation fling-cut switch.
2. The soft starting device of claim 1, wherein the starting cabinet, the outgoing line cabinet and the operating cabinet are all provided with electric switches, and the electric switches, the neutral point switch, the starting switching switch and the operating switching switch are all provided with electric actuators.
3. The soft starting device for voltage reduction compensation according to claim 1, further comprising a control system, wherein the control system is respectively in signal connection with the starting cabinet, the neutral point switch, the outgoing line cabinet, the operating cabinet, the starting switching switch and the operating switching switch, and is used for controlling switching of the starting cabinet, the neutral point switch, the outgoing line cabinet, the operating cabinet, the starting switching switch and the operating switching switch.
4. The buck compensation soft start apparatus of claim 3, wherein the control system is in signal communication with the adjustable resistor for adjusting a resistance of the adjustable resistor.
5. The buck compensation soft start apparatus of claim 3, wherein the control system is a PLC.
6. The buck compensation soft start apparatus of any one of claims 3 to 5, further comprising a touch screen, the touch screen being communicatively coupled to the control system.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023311880.4U CN214626369U (en) | 2020-12-31 | 2020-12-31 | Voltage reduction compensation soft starting device |
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| CN202023311880.4U CN214626369U (en) | 2020-12-31 | 2020-12-31 | Voltage reduction compensation soft starting device |
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| CN214626369U true CN214626369U (en) | 2021-11-05 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115473235A (en) * | 2022-09-23 | 2022-12-13 | 大力电工襄阳股份有限公司 | High-pressure drop compensation solid soft start device and control method thereof |
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2020
- 2020-12-31 CN CN202023311880.4U patent/CN214626369U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115473235A (en) * | 2022-09-23 | 2022-12-13 | 大力电工襄阳股份有限公司 | High-pressure drop compensation solid soft start device and control method thereof |
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