CN114744681A - Control method and device for grid-connected operation of motor and grid-connected operation control system - Google Patents
Control method and device for grid-connected operation of motor and grid-connected operation control system Download PDFInfo
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- CN114744681A CN114744681A CN202210347451.7A CN202210347451A CN114744681A CN 114744681 A CN114744681 A CN 114744681A CN 202210347451 A CN202210347451 A CN 202210347451A CN 114744681 A CN114744681 A CN 114744681A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/40—Synchronising a generator for connection to a network or to another generator
- H02J3/42—Synchronising a generator for connection to a network or to another generator with automatic parallel connection when synchronisation is achieved
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
- H02K21/46—Motors having additional short-circuited winding for starting as an asynchronous motor
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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
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
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Abstract
The embodiment of the application provides a control method and device for grid-connected operation of a motor and a grid-connected operation control system, wherein when a first switch, a second switch and a third switch are all in an off state, if a starting instruction sent by instruction sending equipment is received, the second switch and the third switch are controlled to be closed, an asynchronous starting permanent magnet synchronous motor and a power grid are connected with a frequency converter, and when an operation mode carried in the starting instruction is a grid-connected mode, the third switch is controlled to be opened and the first switch is controlled to be closed when the maximum voltage deviation between the power grid and the frequency converter is determined to be smaller than a preset voltage threshold value after the operation frequency of the asynchronous starting permanent magnet synchronous motor is controlled to reach a target frequency carried in a rotating speed control instruction based on the frequency converter, so that the asynchronous starting permanent magnet synchronous motor is merged into the power grid to operate. The motor can be connected to the power grid through the frequency converter, so that the problems of difficulty in direct grid-connected starting of the motor and unsafe problems caused by over-torque and low voltage during operation are solved.
Description
Technical Field
The invention relates to the technical field of motor operation, in particular to a control method and device for grid-connected operation of a motor and a grid-connected operation control system.
Background
The asynchronous starting permanent magnet synchronous motor is widely applied to a grid-connected constant-speed driving scene due to the advantages of high efficiency, high power density and the like. In actual operation, the asynchronous starting permanent magnet synchronous motor is usually operated in a direct grid connection mode, but the capacity of a power supply transformer is increased due to overlarge starting current of the asynchronous starting permanent magnet synchronous motor in the direct grid connection starting operation process, the torque is overlarge, connecting mechanisms such as a coupler and a shaft extension key are easily damaged, the starting process is longer or the asynchronous starting permanent magnet synchronous motor cannot be switched into to generate large current lasting for a longer time when a large inertia load is driven, and further fault conditions such as excessive heating and rotor permanent magnet demagnetization are caused; in addition, after the asynchronous starting permanent magnet synchronous motor is connected to the grid, once an overlarge load torque or a short-time low voltage of a power grid occurs, step-out occurs, overlarge current and torque are caused, the loss of field of a rotor and mechanical faults are caused, and if a power supply is not timely disconnected, overheating damage can be caused.
Disclosure of Invention
In view of the above, the present invention aims to provide a method and an apparatus for controlling grid-connected operation of a motor, and a grid-connected operation control system, so that an asynchronously-started permanent magnet synchronous motor can be started by a frequency converter, and the problems of difficulty in direct grid-connected start of the asynchronously-started permanent magnet synchronous motor and insecurity caused by over-torque and low voltage during operation are solved.
In a first aspect, an embodiment of the present invention provides a method for controlling grid-connected operation of a motor, where the method is applied to a controller in a grid-connected operation control system, the grid-connected operation control system further includes an asynchronously-started permanent-magnet synchronous motor connected to the controller in a communication manner, a frequency converter, a first switch, a second switch, and a third switch, where the asynchronously-started permanent-magnet synchronous motor is connected to a power grid through the first switch, the frequency converter is connected to the power grid through the second switch, the frequency converter is connected to the asynchronously-started permanent-magnet synchronous motor through the third switch, and the asynchronously-started permanent-magnet synchronous motor is a motor with a damping cage as a rotor; the method comprises the following steps: when the first switch, the second switch and the third switch are all in an off state, the second switch and the third switch are controlled to be closed based on a received starting instruction sent by the instruction sending equipment so as to connect the asynchronous starting permanent magnet synchronous motor and the power grid with the frequency converter; judging whether the operation mode carried in the starting instruction is a grid-connected mode or not; if so, sending a rotating speed control instruction to the frequency converter to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control instruction; determining the maximum voltage deviation between the power grid and the frequency converter; and if the maximum voltage deviation is smaller than the preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency, controlling the third switch to be switched off and the first switch to be switched on so as to enable the asynchronous starting permanent magnet synchronous motor to be merged into a power grid to run.
The method further comprises the following steps: and if the operation mode is judged to be the frequency converter control mode, sending a speed instruction or a torque instruction to the frequency converter so as to trigger the frequency converter to control the asynchronous starting permanent magnet synchronous motor to operate based on the speed instruction or the torque instruction.
Before determining the maximum voltage deviation between the grid and the frequency converter, the method further includes: judging whether a first shutdown instruction sent by instruction sending equipment is received; if so, triggering the frequency converter to stop running, and sequentially disconnecting the third switch and the second switch; if not, the step of determining the maximum voltage deviation between the grid and the frequency converter is performed.
The method further comprises the following steps: and if the maximum voltage deviation is not less than the preset voltage threshold and/or the running frequency of the asynchronous starting permanent magnet synchronous motor does not reach the target frequency, executing a step of judging whether a first shutdown instruction sent by the instruction sending equipment is received.
The grid-connected operation control system also comprises a first voltage sensor and a second voltage sensor which are in communication connection with the controller; the step of determining the maximum voltage deviation between the grid and the frequency converter comprises: receiving a first three-phase voltage instantaneous value of the power grid collected by a first voltage sensor and a second three-phase voltage instantaneous value of the output of the frequency converter collected by a second voltage sensor; calculating voltage deviations corresponding to the three phase sequences respectively based on the first three-phase voltage instantaneous value and the second three-phase voltage instantaneous value; the largest voltage deviation of the three voltage deviations is determined as the maximum voltage deviation.
The grid-connected operation control system also comprises a current sensor in communication connection with the controller; the method further comprises the following steps: receiving a three-phase input current instantaneous value of an asynchronous starting permanent magnet synchronous motor collected by a current sensor; judging whether the maximum current instantaneous value in the three-phase input current instantaneous values is greater than a preset current threshold value or not; if so, the first switch is switched off, the third switch is switched on, a current cut-in command is sent to the frequency converter to trigger the frequency converter to cut in the driving current carried in the current cut-in command of the asynchronous starting permanent magnet synchronous motor, and a rotating speed control command is continuously sent to the frequency converter to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to the target frequency carried in the rotating speed control command.
Before receiving the three-phase input current transient value of the asynchronously-started permanent magnet synchronous motor collected by the current sensor, the method further comprises: judging whether a second shutdown instruction sent by the instruction sending equipment is received; if yes, the first switch and the second switch are sequentially switched off; and if not, executing the step of receiving the three-phase input current instantaneous value of the asynchronous starting permanent magnet synchronous motor collected by the current sensor.
The method further comprises the following steps: and if the maximum current instantaneous value in the three-phase input current instantaneous values is smaller than or equal to the preset current threshold value, executing a step of judging whether a second shutdown instruction sent by the instruction sending equipment is received.
In a second aspect, an embodiment of the present invention further provides a control device for grid-connected operation of a motor, where the control device is applied to a controller in a grid-connected operation control system, the grid-connected operation control system further includes an asynchronously-started permanent magnet synchronous motor, a frequency converter, a first switch, a second switch, and a third switch, the asynchronously-started permanent magnet synchronous motor is connected to a power grid through the first switch, the frequency converter is connected to the power grid through the second switch, the frequency converter is connected to the asynchronously-started permanent magnet synchronous motor through the third switch, and the asynchronously-started permanent magnet synchronous motor is a motor with a damping cage in a rotor; the control device includes: the first control module is used for controlling the second switch and the third switch to be closed based on a received starting-up instruction sent by the instruction sending equipment under the condition that the first switch, the second switch and the third switch are all in an off state so as to connect the asynchronous starting permanent magnet synchronous motor and a power grid with the frequency converter; the judging module is used for judging whether the operation mode carried in the starting instruction is a grid-connected mode or not; the sending module is used for sending a rotating speed control instruction to the frequency converter if the judging module judges that the frequency converter is yes, so as to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control instruction; the determining module is used for determining the maximum voltage deviation between the power grid and the frequency converter; and the second control module is used for controlling the third switch to be switched off and the first switch to be switched on if the maximum voltage deviation is smaller than the preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency so as to enable the asynchronous starting permanent magnet synchronous motor to be merged into a power grid to run.
In a third aspect, an embodiment of the present invention further provides a grid-connected operation control system, where the grid-connected operation control system includes a controller, and an asynchronously-started permanent magnet synchronous motor, a frequency converter, a first switch, a second switch, and a third switch, which are in communication connection with the controller, where the asynchronously-started permanent magnet synchronous motor is connected to a power grid through the first switch, the frequency converter is connected to the power grid through the second switch, the frequency converter is connected to the asynchronously-started permanent magnet synchronous motor through the third switch, and the asynchronously-started permanent magnet synchronous motor is a motor with a damping cage as a rotor; the controller is used for executing the control method for the grid-connected operation of the motor.
The embodiment of the invention has the following beneficial effects:
the embodiment of the application provides a control method and device for grid-connected operation of a motor and a grid-connected operation control system, wherein when a first switch, a second switch and a third switch are all in an off state, if a starting instruction sent by instruction sending equipment is received, the second switch and the third switch are controlled to be closed, an asynchronous starting permanent magnet synchronous motor and a power grid are connected with a frequency converter, and when the operation mode carried in the starting instruction is judged to be a grid-connected mode, a rotating speed control instruction is sent to the frequency converter to trigger the frequency converter to control the operation frequency of the asynchronous starting permanent magnet synchronous motor to the target frequency carried in the rotating speed control instruction; further, when the fact that the maximum voltage deviation between the power grid and the frequency converter is smaller than a preset voltage threshold value and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency is determined, the third switch is controlled to be opened and the first switch is controlled to be closed, and therefore the asynchronous starting permanent magnet synchronous motor is merged into the power grid to run. According to the asynchronous starting permanent magnet synchronous motor grid-connected operation method and device, the asynchronous starting permanent magnet synchronous motor can be operated in a grid-connected mode through the frequency converter, and therefore the problems that the asynchronous starting permanent magnet synchronous motor is difficult to start in a direct grid-connected mode and unsafe due to over-torque and low voltage during operation are solved.
Furthermore, in the above mode, the asynchronous starting permanent magnet synchronous motor is a motor with a rotor provided with a damping cage, and mainly plays a damping role, so that the dynamic stability of the motor during grid-connected operation is effectively ensured.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic structural diagram of a grid-connected operation control system according to an embodiment of the present invention;
fig. 2 is a flowchart of a control method for grid-connected operation of a motor according to an embodiment of the present invention;
FIG. 3 is a flow chart of another method for controlling grid-connected operation of an electric motor according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another grid-connected operation control system according to an embodiment of the present invention;
fig. 5 is a flowchart of another control method for grid-connected operation of an electric motor according to an embodiment of the present invention.
Icon:
100-a controller; 101-asynchronous starting permanent magnet synchronous motor; 102-a frequency converter; k1 — first switch; k2 — second switch; k3 — third switch; CV1 — first voltage sensor; CV2 — second voltage sensor; CT-current sensor.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Considering that the existing asynchronous starting permanent magnet synchronous motor may have the unsafe problems caused by difficult starting, excessive torque and low voltage during operation in the direct grid-connected starting operation process; based on the above, the control method and device for the grid-connected operation of the motor and the grid-connected operation control system provided by the embodiment of the invention can perform the grid-connected operation of the asynchronous starting permanent magnet synchronous motor through the frequency converter, thereby overcoming the problems of difficulty in direct grid-connected starting of the asynchronous starting permanent magnet synchronous motor and unsafe problems caused by over-torque and low voltage during operation.
For the convenience of understanding the present embodiment, the following first describes in detail a control method for grid-connected operation of a motor according to an embodiment of the present invention. As shown in fig. 1, the controller in the grid-connected operation control system includes the controller 100, and an asynchronous starting permanent magnet synchronous motor 101, a frequency converter 102, a first switch K1, a second switch K2, and a third switch K3 which are in communication connection with the controller 100, where the asynchronous starting permanent magnet synchronous motor 101 is connected to a power grid through the first switch K1, the frequency converter 102 is connected to the power grid through the second switch K2, the frequency converter 102 is connected to the asynchronous starting permanent magnet synchronous motor 101 through the third switch K3, the asynchronous starting permanent magnet synchronous motor is a motor with a damping cage on a rotor, and a dotted line in fig. 1 represents communication connection.
The power grid in fig. 1 is a three-phase power grid, which can be represented by U, V, W, and the first switch, the second switch and the third switch can be mechanical switches or electronic switches, which can be selected according to actual needs and are not limited herein.
The damping cage may be one structure similar to that of cage asynchronous motor rotor cage or one closed coil structure similar to that of wound asynchronous motor rotor winding and comprising cast aluminum, cast copper, copper bars or aluminum bars. The damping cage is low in shape complexity and small in area, so that a damping effect can be well achieved, and the dynamic stability of the motor during grid-connected operation is further guaranteed.
Based on the controller, the present embodiment provides a method for controlling grid-connected operation of a motor, where, referring to a flowchart of the method for controlling grid-connected operation of a motor shown in fig. 2, the method specifically includes the following steps:
step S202, when the first switch, the second switch and the third switch are all in an off state, the second switch and the third switch are controlled to be closed based on a received starting instruction sent by the instruction sending equipment so as to connect the asynchronous starting permanent magnet synchronous motor and a power grid with the frequency converter;
fig. 1 is a schematic structural diagram illustrating that the first switch, the second switch, and the third switch are all in an off state, and the instruction sending device is an upper computer or an instruction switching device in this embodiment, which is not limited herein.
The starting-up instruction sent by the instruction sending equipment is an instruction for controlling the asynchronous starting permanent magnet synchronous motor to start running, and if the controller receives the starting-up instruction, the second switch and the third switch can be controlled to be closed, so that the frequency converter is connected to a power grid through the second switch, and the asynchronous starting permanent magnet synchronous motor is connected with the frequency converter through the third switch.
Step S204, judging whether the operation mode carried in the starting instruction is a grid-connected mode;
the grid-connected mode refers to a mode for connecting the asynchronous starting permanent magnet synchronous motor into a power grid to operate.
Step S206, if yes, a rotating speed control instruction is sent to the frequency converter so as to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control instruction;
in general, the target frequency carried in the speed control command may be determined by the same rated frequency and slip frequency as the grid frequency, i.e. the target frequency is: fv-fb; wherein, fn is a rated frequency, fb is a slip frequency, and the value range of fb is: [ 0.5%. fn, 5%. fn ]. For example, fn is 50Hz, fb is 1Hz, and the target frequency fv is 49Hz, i.e. the operating frequency of the asynchronous starting permanent magnet synchronous motor needs to be adjusted to 49 Hz.
Step S208, determining the maximum voltage deviation between the power grid and the frequency converter;
and step S210, if the maximum voltage deviation is smaller than a preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches a target frequency, controlling the third switch to be switched off and the first switch to be switched on so as to enable the asynchronous starting permanent magnet synchronous motor to be merged into a power grid to run.
If the maximum voltage deviation is smaller than the preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency, the requirement that the asynchronous starting permanent magnet synchronous motor is merged into the power grid is met, therefore, the controller can disconnect the asynchronous starting permanent magnet synchronous motor from the frequency converter by controlling the third switch to be switched off, and control the first switch to be switched on to enable the asynchronous starting permanent magnet synchronous motor to be merged into the power grid to continue running. The preset voltage threshold may be set according to actual needs, and is not limited herein.
The embodiment of the application provides a control method for grid-connected operation of a motor, wherein when a first switch, a second switch and a third switch are all in an off state, if a starting instruction sent by instruction sending equipment is received, the second switch and the third switch are controlled to be closed, an asynchronous starting permanent magnet synchronous motor and a power grid are connected with a frequency converter, and when an operation mode carried in the starting instruction is judged to be a grid-connected mode, a rotating speed control instruction is sent to the frequency converter to trigger the frequency converter to control the operation frequency of the asynchronous starting permanent magnet synchronous motor to a target frequency carried in the rotating speed control instruction; further, when the fact that the maximum voltage deviation between the power grid and the frequency converter is smaller than a preset voltage threshold value and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency is determined, the third switch is controlled to be opened and the first switch is controlled to be closed, and therefore the asynchronous starting permanent magnet synchronous motor is merged into the power grid to run. According to the asynchronous starting permanent magnet synchronous motor grid-connected system, the asynchronous starting permanent magnet synchronous motor can be operated in a grid-connected mode through the frequency converter, and therefore the problems that the asynchronous starting permanent magnet synchronous motor is difficult to start in a direct grid-connected mode and unsafe problems caused by over-torque and low voltage in operation are solved.
The embodiment provides another control method for grid-connected operation of the motor, which is realized on the basis of the embodiment; as shown in fig. 3, another method for controlling a grid-connected operation of a motor includes the following steps:
step S302, when the first switch, the second switch and the third switch are all in an off state, the second switch and the third switch are controlled to be closed based on a received starting instruction sent by instruction sending equipment so as to connect the asynchronous starting permanent magnet synchronous motor and a power grid with a frequency converter;
step S304, judging whether the operation mode carried in the starting instruction is a grid-connected mode;
specifically, the operation modes include a grid-connected mode and a frequency converter control mode, where the grid-connected mode is a mode in which the asynchronous starting permanent magnet synchronous motor is connected to a power grid for operation, and the frequency converter control mode is a mode in which the frequency converter is used to drive the asynchronous starting permanent magnet synchronous motor to operate, in this embodiment, if the operation mode is the grid-connected mode, step S306 is executed, and if the operation mode is not the grid-connected mode, that is, the operation mode is the frequency converter control mode, step S316 is executed.
Step S306, sending a rotating speed control instruction to the frequency converter to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control instruction;
step S308, judging whether a first shutdown instruction sent by the instruction sending equipment is received;
if not, step S310 is performed, and if yes, step S318 is performed.
Step S310, determining the maximum voltage deviation between the power grid and the frequency converter;
on the basis of fig. 1, as shown in fig. 4, the grid-connected operation control system further includes a first voltage sensor CV1 and a second voltage sensor CV2 communicatively connected to the controller 100, wherein the first voltage sensor CV1 is installed on the power grid and is configured to acquire a first three-phase voltage instantaneous value (UA, UB, UC) of the power grid, and the second voltage sensor CV2 is installed at an output end of the frequency converter and is configured to acquire a second three-phase voltage instantaneous value (UA, UB, UC) of the output end of the frequency converter, where three-phase sequences of the power grid and the frequency converter are consistent, and therefore, voltage deviations corresponding to three phase sequences, respectively, can be calculated based on the acquired first three-phase voltage instantaneous value and second three-phase voltage instantaneous value, respectively: vub ═ UA-UA; Vvb-UB; vwb ═ UC-UC; then, the maximum voltage deviation Vb is max (Vub, Vvb, Vwb), and max () is a function that takes the maximum value, that is, the maximum voltage deviation of the three voltage deviations is determined as the maximum voltage deviation Vb.
Step S312, if the maximum voltage deviation is smaller than the preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency, the third switch is controlled to be opened and the first switch is controlled to be closed, so that the asynchronous starting permanent magnet synchronous motor is merged into a power grid to run;
step S314, if the maximum voltage deviation is not less than the preset voltage threshold and/or the running frequency of the asynchronous starting permanent magnet synchronous motor does not reach the target frequency, executing a step of judging whether a first shutdown instruction sent by the instruction sending equipment is received;
if the maximum voltage deviation is not less than the preset voltage threshold and/or the running frequency of the asynchronous starting permanent magnet synchronous motor does not reach the target frequency, it indicates that the asynchronous starting permanent magnet synchronous motor does not meet the requirement of being incorporated into the power grid, and therefore, the step S308 is continuously executed.
Step S316, sending a speed instruction or a torque instruction to the frequency converter to trigger the frequency converter to control the asynchronous starting permanent magnet synchronous motor to operate based on the speed instruction or the torque instruction;
when the operation mode is the frequency converter control mode, the frequency converter can be used for directly controlling the asynchronous starting permanent magnet synchronous motor to operate.
And step S318, triggering the frequency converter to stop running, and sequentially disconnecting the third switch and the second switch.
After the frequency converter stops running, the asynchronous starting permanent magnet synchronous motor also stops running slowly.
The embodiment provides another control method for grid-connected operation of the motor, which is realized on the basis of the embodiment; as shown in fig. 5, another method for controlling a grid-connected operation of a motor includes the following steps:
step S502, when the first switch, the second switch and the third switch are all in an off state, the second switch and the third switch are controlled to be closed based on a received starting instruction sent by the instruction sending equipment so as to connect the asynchronous starting permanent magnet synchronous motor and the power grid with the frequency converter;
step S504, judge whether the running mode carried in the starting up order is the mode of connecting to the power networks;
step S506, if yes, a rotating speed control instruction is sent to the frequency converter to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control instruction;
step S508, determining the maximum voltage deviation between the power grid and the frequency converter;
step S510, if the maximum voltage deviation is smaller than a preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches a target frequency, controlling a third switch to be switched off and a first switch to be switched on so as to enable the asynchronous starting permanent magnet synchronous motor to be merged into a power grid to run;
step S512, judging whether a second shutdown instruction sent by the instruction sending equipment is received;
after the asynchronous starting permanent magnet synchronous motor is merged into the power grid to normally operate, the controller needs to inquire whether a second shutdown instruction is received in real time, if so, step S514 is executed, and if not, step S516 is executed, where the second shutdown instruction is the same as the first shutdown instruction, which is not described herein again.
Step S514, sequentially disconnecting the first switch and the second switch;
after the first switch and the second switch are disconnected, the asynchronous starting permanent magnet synchronous motor and the frequency converter both stop running slowly.
Step S516, receiving a three-phase input current instantaneous value of the asynchronous starting permanent magnet synchronous motor collected by a current sensor;
as shown in fig. 4, the grid-connected operation control system further includes a current sensor CT communicatively connected to the controller 100, where the current sensor CT is installed on a connection circuit between the asynchronous starting permanent magnet synchronous motor and the power grid, and three-phase input current instantaneous values of the asynchronous starting permanent magnet synchronous motor collected by the current sensor are IA, IB, and IC.
Step S518, determining whether a maximum current instantaneous value of the three-phase input current instantaneous values is greater than a preset current threshold value;
the maximum current transient is the largest current transient among the three-phase input current transients, and may be determined by: in this embodiment, the preset current threshold value range is: (1.05 to 2.5). IN.1.414, where IN is the effective value of the rated current.
If the maximum current transient is greater than the predetermined current threshold, step S520 is performed, and if the maximum current transient is less than or equal to the predetermined current threshold, step S512 is performed.
And S520, disconnecting the first switch, closing the third switch, sending a current cut-in command to the frequency converter to trigger the frequency converter to cut in the driving current carried in the current cut-in command to the asynchronous starting permanent magnet synchronous motor, and continuously executing the step of sending a rotating speed control command to the frequency converter to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to the target frequency carried in the rotating speed control command.
When the maximum current instantaneous value is greater than the preset current threshold value, it is described that the asynchronous starting permanent magnet synchronous motor operates abnormally after being merged into the power grid, in this embodiment, the asynchronous starting permanent magnet synchronous motor may be reconnected to the frequency converter, and steps S506 to S510 are repeatedly executed, so that the frequency converter controls the asynchronous starting permanent magnet synchronous motor to operate normally and then reconnects to the power grid to operate.
The control method for the grid-connected operation of the motor in the embodiment mainly aims at equipment which is connected to the grid and operates at a constant speed for a long time, and most of the actual operation time is the grid-connected operation, so that the loss of a frequency converter and the high-frequency additional loss of a motor body caused by the high-frequency wave power supply of the frequency converter are avoided, the overall efficiency of a grid-connected operation control system is improved, and the energy efficiency of partial loads such as a fan, a water pump and the like which operate at a constant speed is improved. For constant-speed load equipment with longer working time, the saved electricity cost can be more than the cost increased by adding a frequency converter, the control method for the grid-connected operation of the motor is also suitable for equipment which runs at constant speed in part of time and runs at variable speed in part of time, and the overall energy efficiency of the control system for the grid-connected operation is improved.
The grid-connected operation control system provided by the embodiment of the invention has the same technical characteristics as the control method for the grid-connected operation of the motor provided by the embodiment, so that the same technical problems can be solved, and the same technical effect is achieved.
The method and the device for controlling the grid-connected operation of the motor and the computer program product of the grid-connected operation control system provided by the embodiment of the invention comprise a computer readable storage medium storing program codes, instructions included in the program codes can be used for executing the method in the previous method embodiment, and specific implementation can refer to the method embodiment and is not described herein again.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process of the system described above may refer to the corresponding process in the foregoing method embodiment, and is not described herein again.
In addition, in the description of the embodiments of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases for those skilled in the art.
The functions may be stored in a computer-readable storage medium if they are implemented in the form of software functional units and sold or used as separate products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that the following embodiments are merely illustrative of the present invention, and not restrictive, and the scope of the present invention is not limited thereto: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The control method for the grid-connected operation of the motor is characterized by being applied to a controller in a grid-connected operation control system, wherein the grid-connected operation control system further comprises an asynchronous starting permanent magnet synchronous motor, a frequency converter, a first switch, a second switch and a third switch which are in communication connection with the controller, the asynchronous starting permanent magnet synchronous motor is connected with a power grid through the first switch, the frequency converter is connected with the power grid through the second switch, the frequency converter is connected with the asynchronous starting permanent magnet synchronous motor through the third switch, and the asynchronous starting permanent magnet synchronous motor is a motor with a damping cage as a rotor; the method comprises the following steps:
when the first switch, the second switch and the third switch are all in an off state, the second switch and the third switch are controlled to be closed based on a received starting instruction sent by instruction sending equipment, so that the asynchronous starting permanent magnet synchronous motor and the power grid are connected with the frequency converter;
judging whether the operation mode carried in the starting instruction is a grid-connected mode or not;
if so, sending a rotating speed control instruction to the frequency converter to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control instruction;
determining a maximum voltage deviation between the grid and the frequency converter;
and if the maximum voltage deviation is smaller than a preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency, controlling the third switch to be switched off and the first switch to be switched on so as to enable the asynchronous starting permanent magnet synchronous motor to be merged into the power grid to run.
2. The control method according to claim 1, characterized in that the method further comprises:
and if the operation mode is judged to be the frequency converter control mode, sending a speed instruction or a torque instruction to the frequency converter so as to trigger the frequency converter to control the asynchronous starting permanent magnet synchronous motor to operate based on the speed instruction or the torque instruction.
3. The control method of claim 1, wherein prior to determining the maximum voltage deviation between the grid and the frequency converter, the method further comprises:
judging whether a first shutdown instruction sent by the instruction sending equipment is received or not;
if yes, triggering the frequency converter to stop running, and sequentially disconnecting the third switch and the second switch;
if not, executing the step of determining the maximum voltage deviation between the power grid and the frequency converter.
4. The control method according to claim 3, characterized in that the method further comprises:
and if the maximum voltage deviation is not less than a preset voltage threshold and/or the running frequency of the asynchronous starting permanent magnet synchronous motor does not reach the target frequency, executing a step of judging whether a first shutdown instruction sent by the instruction sending equipment is received.
5. The control method of claim 1, wherein the grid-tie operation control system further comprises a first voltage sensor and a second voltage sensor communicatively coupled to the controller;
the step of determining a maximum voltage deviation between the grid and the frequency converter comprises:
receiving a first three-phase voltage instantaneous value of the power grid acquired by the first voltage sensor and a second three-phase voltage instantaneous value of the output end of the frequency converter acquired by the second voltage sensor;
calculating voltage deviations corresponding to the three phase sequences respectively based on the first three-phase voltage instantaneous value and the second three-phase voltage instantaneous value;
determining a maximum voltage deviation as a maximum voltage deviation.
6. The control method of claim 1, wherein the grid-tie operation control system further comprises a current sensor in communicative connection with the controller; the method further comprises the following steps:
receiving a three-phase input current instantaneous value of the asynchronous starting permanent magnet synchronous motor collected by the current sensor;
judging whether the maximum current instantaneous value in the three-phase input current instantaneous values is greater than a preset current threshold value or not;
if so, the first switch is opened, the third switch is closed, a current cut-in command is sent to the frequency converter to trigger the frequency converter to cut in the driving current carried in the current cut-in command to the asynchronous starting permanent magnet synchronous motor, and a rotating speed control command is continuously sent to the frequency converter to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control command.
7. The control method of claim 6, wherein prior to receiving a three-phase input current transient of the asynchronously-started permanent magnet synchronous motor collected by the current sensor, the method further comprises:
judging whether a second shutdown instruction sent by the instruction sending equipment is received or not;
if yes, sequentially opening the first switch and the second switch;
and if not, executing the step of receiving the three-phase input current instantaneous value of the asynchronous starting permanent magnet synchronous motor collected by the current sensor.
8. The control method according to claim 7, characterized in that the method further comprises:
and if the maximum current instantaneous value in the three-phase input current instantaneous values is smaller than or equal to a preset current threshold value, executing a step of judging whether a second shutdown instruction sent by the instruction sending equipment is received.
9. The control device for the grid-connected operation of the motor is characterized by being applied to a controller in a grid-connected operation control system, and the grid-connected operation control system further comprises an asynchronous starting permanent magnet synchronous motor, a frequency converter, a first switch, a second switch and a third switch which are in communication connection with the controller, wherein the asynchronous starting permanent magnet synchronous motor is connected with a power grid through the first switch, the frequency converter is connected with the power grid through the second switch, the frequency converter is connected with the asynchronous starting permanent magnet synchronous motor through the third switch, and the asynchronous starting permanent magnet synchronous motor is a motor with a damping cage as a rotor; the control device includes:
the first control module is used for controlling the second switch and the third switch to be closed based on a received starting-up instruction sent by the instruction sending equipment under the condition that the first switch, the second switch and the third switch are all in an off state so as to connect the asynchronous starting permanent magnet synchronous motor and the power grid with the frequency converter;
the judging module is used for judging whether the operation mode carried in the starting instruction is a grid-connected mode or not;
the sending module is used for sending a rotating speed control instruction to the frequency converter if the judging module judges that the frequency converter is yes, so as to trigger the frequency converter to control the running frequency of the asynchronous starting permanent magnet synchronous motor to reach the target frequency carried in the rotating speed control instruction;
the determining module is used for determining the maximum voltage deviation between the power grid and the frequency converter;
and the second control module is used for controlling the third switch to be switched off and the first switch to be switched on if the maximum voltage deviation is smaller than a preset voltage threshold and the running frequency of the asynchronous starting permanent magnet synchronous motor reaches the target frequency, so that the asynchronous starting permanent magnet synchronous motor is merged into the power grid to run.
10. The grid-connected operation control system is characterized by comprising a controller, an asynchronous starting permanent magnet synchronous motor, a frequency converter, a first switch, a second switch and a third switch, wherein the asynchronous starting permanent magnet synchronous motor, the frequency converter, the first switch, the second switch and the third switch are in communication connection with the controller;
the controller is used for executing the control method of the grid-connected operation of the motor according to any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210347451.7A CN114744681A (en) | 2022-04-01 | 2022-04-01 | Control method and device for grid-connected operation of motor and grid-connected operation control system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210347451.7A CN114744681A (en) | 2022-04-01 | 2022-04-01 | Control method and device for grid-connected operation of motor and grid-connected operation control system |
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| Publication Number | Publication Date |
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| CN114744681A true CN114744681A (en) | 2022-07-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210347451.7A Pending CN114744681A (en) | 2022-04-01 | 2022-04-01 | Control method and device for grid-connected operation of motor and grid-connected operation control system |
Country Status (1)
| Country | Link |
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| CN (1) | CN114744681A (en) |
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2022
- 2022-04-01 CN CN202210347451.7A patent/CN114744681A/en active Pending
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