Motor control system and power grid treatment method

Abstract

The embodiment of the application provides a motor control system and a power grid treatment method, the motor control system comprises a frequency converter group, a motor and an electric energy quality analysis module; the electric energy quality analysis module monitors power supply data of a power grid in real time and generates power supply quality information; the frequency converter group receives the power supply quality information, outputs reactive current to a power frequency power grid according to the power supply quality information, so as to compensate the reactive power of the power frequency power grid to a preset compensation target, so that the reactive power of the power frequency power grid is close to the preset compensation target in real time, the voltage of the power frequency power grid is stabilized, the power factor of the power frequency power grid is improved, the electric energy quality of the power grid is improved, and the problem that the electric energy quality of the power grid is poor due to power consumption of a factory is solved.

Description

Technical Field

[0001] This application relates to the field of power grid management technology, and in particular to a motor control system and a power grid management method. Background Technology

[0002] In large-scale industrial production settings, such as mines, chemical plants, sewage treatment plants, and pumping stations, electric motors (typically 6kV or 10kV) are widely used to drive large load equipment (such as fans, pumps, and compressors). When a motor is started directly at the power frequency, it will generate an inrush current as high as 5-8 times its rated current, which not only causes a significant impact on the power grid but may also lead to problems such as voltage drops and equipment damage.

[0003] In existing technologies, soft starting is typically employed, which involves using a frequency converter to gradually increase the motor speed to the power frequency, achieving a smooth start. After the soft start is complete, the motor switches to power grid operation, while the frequency converter enters a shutdown or power-off state.

[0004] However, most large factory loads are inductive loads such as motors, which have a low overall power factor. This can easily lead to a low power factor in electricity consumption. In addition, there are some electrical devices in the factory that emit large harmonics, resulting in poor power quality for the entire factory and affecting the power grid's overall power quality. Summary of the Invention

[0005] The motor control system and power grid management method provided in this application are used to solve the problem of poor power quality caused by factory power consumption in the prior art.

[0006] In a first aspect, embodiments of this application provide a motor control system, including a frequency converter group, a motor, and a power quality analysis module; the frequency converter group includes one or at least two frequency converters, the input terminal of the frequency converter group is connected to the output terminal of the power frequency grid, and the output terminal of each frequency converter is connected to at least one of the motors; the input terminal of the motor is connected to the output terminal of the frequency converter group and the output terminal of the power frequency grid; the input terminal of the power quality analysis module is disposed between the input terminal of the frequency converter group and the output terminal of the power frequency grid, the power quality analysis module is connected to the frequency converters, and the power quality analysis module is used to collect power supply data of the power frequency grid, obtain power supply quality information based on the power supply data, and send the power supply quality information to the frequency converter group; the frequency converter group is used to output reactive current to the power frequency grid according to the power supply quality information to compensate the reactive power of the power frequency grid to a preset compensation target.

[0007] In one possible implementation, the system further includes a first disconnect switch, a second disconnect switch, a third disconnect switch, and a fourth disconnect switch; the input terminal of the frequency converter group is connected to the power grid via the first disconnect switch, and the output terminal of the frequency converter group is connected to the input terminal of the motor via the second disconnect switch and the fourth disconnect switch; the input terminal of the motor is connected to the power grid via the fourth disconnect switch and the third disconnect switch; the input terminal of the power quality analysis module is located between the first disconnect switch and the output terminal of the power grid.

[0008] In one possible implementation, the system further includes a relay device, the output of which is connected to the power quality analysis module, and the relay device is connected to the frequency converter group; the power quality analysis module is used to send the power supply quality information to the relay device; the relay device is used to send the received power supply quality information to the frequency converter group.

[0009] In one possible implementation, the inverter group includes at least two inverters; the relay device is used to determine a quality compensation allocation strategy based on the power quality information and the configuration information of the inverter group; allocate the power quality information according to the quality compensation allocation strategy to obtain allocated power quality information, and send the allocated power quality information to the corresponding inverters; each inverter is used to output reactive current to the power frequency grid according to the corresponding allocated power quality information to compensate the reactive power of the power frequency grid to the preset compensation target.

[0010] In one possible implementation, the power quality analysis module includes at least a voltage sampling unit, a current sampling unit, a data analysis unit, and a data transmission unit; the voltage sampling unit is used to collect voltage data of the power frequency grid; the current sampling unit is used to collect current data of the power frequency grid; the data analysis unit is used to analyze the collected voltage data and current data to obtain the power supply quality information; and the data transmission unit is used to send the power supply quality information.

[0011] In one possible implementation, the operating modes of the frequency converter group include at least a soft-start mode and a power grid management mode; when the frequency converter group is operating in the soft-start mode, the first disconnect switch, the second disconnect switch, and the fourth disconnect switch are closed; when the frequency converter group is operating in the power grid management mode, the first disconnect switch, the second disconnect switch, and the third disconnect switch are closed.

[0012] In one possible implementation, when the motor is operating in grid-driven mode, the third disconnect switch and the fourth disconnect switch are closed.

[0013] In one possible implementation, a substation, a power supply bus, and a transformer are provided between the output terminal of the power frequency grid and the input terminal of the frequency converter group; the input terminal of the power quality analysis module is provided between the substation and the output terminal of the power frequency grid, and / or between the substation and the power supply bus, and / or between the power supply bus and the transformer, and / or between the transformer and the first disconnecting switch.

[0014] Secondly, embodiments of this application provide a power grid management method applied to the motor control system described in any one of the first aspects. The method includes: collecting power supply data of the power frequency grid through a power quality analysis module, obtaining power supply quality information based on the power supply data, and sending the power supply quality information to a frequency converter group; and outputting reactive current to the power frequency grid through the frequency converter group based on the power supply quality information to compensate the reactive power of the power frequency grid to a preset compensation target.

[0015] In one possible implementation, the inverter group includes at least two inverters, one of which is a master inverter and at least one cooperating inverter; the preset compensation target includes a preset master control compensation target and a preset cooperating compensation target; the step of outputting reactive current to the power grid through the inverter group according to the power quality information to compensate the reactive power of the power grid to the preset compensation target includes: determining the quality compensation allocation information corresponding to each inverter based on the power quality information and the configuration information of the inverter group through the master control inverter; sending the quality compensation allocation information to each cooperating inverter through the master control inverter; and the master control inverter and each cooperating inverter outputting reactive current to the power grid according to the quality compensation allocation information to compensate the reactive power of the power grid to the preset compensation target.

[0016] In one possible implementation, the inverter group includes at least two inverters; the step of collecting power supply data from the power frequency grid through the power quality analysis module, obtaining power quality information based on the power supply data, and sending the power quality information to the inverter group includes: collecting power supply data from the power frequency grid through the power quality analysis module, obtaining power quality information based on the power supply data; determining the quality compensation allocation information corresponding to each inverter in the inverter group based on the power quality information and the configuration information of the inverter group; and sending the quality compensation allocation information to each inverter in the inverter group; the step of outputting reactive current to the power frequency grid through the inverter group according to the power quality information to compensate the reactive power of the power frequency grid to a preset compensation target includes: each inverter in the inverter group outputting reactive current to the power frequency grid according to the corresponding quality compensation allocation information to compensate the reactive power of the power frequency grid to the preset compensation target.

[0017] In one possible implementation, the inverter group includes at least two inverters, and the motor control system further includes a relay device; the step of collecting power supply data from the power grid through the power quality analysis module, obtaining power quality information based on the power supply data, and sending the power quality information to the inverter group includes:

[0018] The power quality analysis module collects power supply data from the industrial frequency grid, obtains power quality information based on the power supply data, and sends the power quality information to a relay device. The relay device, based on the power quality information and the configuration information of the inverter group, determines the corresponding quality compensation allocation information for each inverter in the inverter group; the quality compensation allocation information is then sent to each inverter in the inverter group. The step of outputting reactive current to the industrial frequency grid through the inverter group based on the power quality information to compensate the reactive power of the industrial frequency grid to a preset compensation target includes: receiving the quality compensation allocation information sent by the relay device through each inverter; and outputting reactive current to the industrial frequency grid according to the corresponding quality compensation allocation information through each inverter to compensate the reactive power of the industrial frequency grid to the preset compensation target.

[0019] In one possible implementation, before collecting power supply data from the power frequency grid via the power quality analysis module, obtaining power quality information based on the power supply data, and sending the power quality information to the frequency converter group, the method further includes: controlling the first disconnect switch to close, causing the frequency converter group to enter a standby preparation state; in the standby preparation state, controlling the second disconnect switch and the fourth disconnect switch to close via the frequency converter group, causing the frequency converter group to operate in a soft start mode; while the frequency converter group is operating in the soft start mode, controlling the third disconnect switch to close based on the operating status of the motor, causing the motor to operate in a grid-driven mode; when the motor is operating in the grid-driven mode, controlling the first disconnect switch and the second disconnect switch to close, causing the frequency converter group to operate in a grid management mode.

[0020] In one possible implementation, before the power quality analysis module collects power supply data from the power frequency grid, obtains power quality information based on the power supply data, and sends the power quality information to the inverter group, the method further includes: controlling the first disconnect switch to close, causing the inverter group to enter a standby preparation state; in the standby preparation state, controlling the first disconnect switch, the second disconnect switch, and the fourth disconnect switch to close, causing the inverter group to operate in a grid management mode.

[0021] The motor control system and power grid management method provided in this application include a frequency converter group, a motor, and a power quality analysis module. The power quality analysis module monitors the power grid supply data in real time and generates power quality information. The frequency converter group receives the power quality information and outputs reactive current to the power frequency grid according to the power quality information to compensate the reactive power of the power frequency grid to a preset compensation target. This ensures that the reactive power of the power frequency grid approaches the preset compensation target in real time, stabilizes the voltage of the power frequency grid, improves the power factor of the power frequency grid, and enhances the power quality of the power grid, thus solving the problem of poor power quality caused by factory power consumption. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] Figure 1 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 1 ;

[0024] Figure 2 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 2 ;

[0025] Figure 3A schematic diagram of a motor control system provided in one embodiment of this application. Figure 3 ;

[0026] Figure 4 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 4 ;

[0027] Figure 5 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 5 ;

[0028] Figure 6 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 6 ;

[0029] Figure 7 A flowchart illustrating a power grid management method provided in one embodiment of this application;

[0030] Figure 8 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 7 ;

[0031] Figure 9 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 8 ;

[0032] Figure 10 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 9 .

[0033] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0035] The technical solution of this application involves the collection, storage, use, processing, transmission, provision and disclosure of user personal information and data, which comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0036] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with the relevant laws, regulations and standards of the relevant regions, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0037] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0038] Figure 1 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 1 ,like Figure 1 As shown, the motor control system provided in this embodiment includes a frequency converter group, a motor, and a power quality analysis module.

[0039] The inverter group includes one or at least two inverters. The input terminal of the inverter group is connected to the output terminal of the power grid. The output terminal of each inverter is connected to at least one motor. The input terminal of the motor is connected to the output terminal of the inverter group and the output terminal of the power grid. The input terminal of the power quality analysis module is located between the input terminal of the inverter group and the output terminal of the power grid. The power quality analysis module is connected to the inverters and is used to collect power supply data from the power grid, obtain power quality information based on the power supply data, and send the power quality information to the inverter group. The inverter group is used to output reactive current to the power grid according to the power quality information to compensate the reactive power of the power grid to a preset compensation target.

[0040] The motor control system provided in this embodiment is applicable to high-voltage power grids, with the high voltage range of the high-voltage power grid being, for example, 1kV to 220kV.

[0041] The power supply data of the power frequency grid includes voltage data and current data.

[0042] The power supply quality information includes parameters related to reactive power, such as the current reactive power demand of the power grid, power factor, voltage fluctuation, harmonic content, current RMS value, harmonic current value, and voltage RMS value. These are used to provide the decision-making basis for the frequency converter group to carry out reactive power compensation and to clarify the current reactive power deficit or surplus of the power frequency grid.

[0043] The preset compensation target is used to indicate a specific state or parameter value that the power frequency grid is expected to achieve through the reactive power compensation action of the frequency converter group. For example, it is a specific value or range, such as compensating the power factor of the grid to above 0.95, maintaining the voltage of a specific node within the allowable deviation range of the rated value, or directly reducing the reactive power demand of the grid to zero (i.e., achieving full compensation).

[0044] In some embodiments, a preset compensation target is used as a preset set value. The frequency converter group can dynamically adjust its output reactive current according to the difference between the power supply quality information and the preset compensation target. For example, by calculating the difference between the power supply quality information and the preset compensation target, a reactive current with corresponding amplitude and phase is output and injected into the power frequency grid.

[0045] In this process, the frequency converter group outputs reactive current to the power frequency grid based on the power supply quality information to compensate the reactive power of the power frequency grid to the preset compensation target. That is, the frequency converter group operates in the grid management mode.

[0046] In summary, in this embodiment, the motor control system includes a frequency converter group, a motor, and a power quality analysis module. The power quality analysis module monitors the power grid supply data in real time and generates power quality information. The frequency converter group receives the power quality information and outputs reactive current to the power frequency grid according to the power quality information to compensate the reactive power of the power frequency grid to a preset compensation target. This ensures that the reactive power of the power frequency grid approaches the preset compensation target in real time, stabilizes the voltage of the power frequency grid, improves the power factor of the power frequency grid, and enhances the power quality of the grid, thus solving the problem of poor power quality caused by factory power consumption.

[0047] In large factories, most loads are inductive loads such as motors, which have a low overall power factor, easily leading to low power consumption. In addition, there are some electrical equipment with high harmonic emissions in the factory. The motor control system provided in this application can solve the problem of poor power quality of the entire factory and improve the power quality of the grid.

[0048] exist Figure 1 Based on the system diagram of the motor control system shown, Figure 2 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 2 ,like Figure 2 As shown, the motor control system provided in this embodiment also includes a first disconnect switch, a second disconnect switch, a third disconnect switch, and a fourth disconnect switch.

[0049] The inverter group's input terminal is connected to the power grid via a first disconnecting switch, and the inverter group's output terminal is connected to the motor's input terminal via a second disconnecting switch and a fourth disconnecting switch. The motor's input terminal is connected to the power grid via a fourth disconnecting switch and a third disconnecting switch. The power quality analysis module's input terminal is located between the first disconnecting switch and the power grid's output terminal.

[0050] exist Figure 2 Based on the system diagram of the motor control system shown, Figure 3 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 3 ,like Figure 3 As shown, the motor control system provided in this embodiment also includes a transfer device. The output terminal of the power quality analysis module is connected to the transfer device, and the transfer device is connected to the frequency converter group.

[0051] The power quality analysis module is used to send power quality information to the relay equipment; the relay equipment is used to send the received power quality information to the frequency converter group.

[0052] The relay equipment is the device responsible for forwarding and processing data communication between the power quality analysis module and the frequency converter group; for example, the relay equipment is an industrial communication gateway, a programmable logic controller, a communication server or front-end machine, an industrial switch or router, or a wireless communication concentrator.

[0053] The connection methods between the transfer equipment and the frequency converter group include wireless communication connection and / or wired communication connection.

[0054] In one possible implementation, the relay equipment is only used for relaying information and does not perform the data processing process that determines the quality compensation allocation strategy.

[0055] Furthermore, in one possible implementation, the inverter group includes at least two inverters; a relay device is used to determine a quality compensation allocation strategy based on power quality information and the configuration information of the inverter group; allocate the power quality information according to the quality compensation allocation strategy to obtain allocated power quality information, and send the allocated power quality information to the corresponding inverters; each inverter is used to output reactive current to the power frequency grid according to the corresponding allocated power quality information to compensate the reactive power of the power frequency grid to a preset compensation target.

[0056] Furthermore, in one possible implementation, the power quality analysis module includes at least a voltage sampling unit, a current sampling unit, a data analysis unit, and a data transmission unit; the voltage sampling unit is used to collect voltage data from the power frequency grid; the current sampling unit is used to collect current data from the power frequency grid; the data analysis unit is used to analyze the collected voltage and current data to obtain power supply quality information; and the data transmission unit is used to send the power supply quality information.

[0057] Furthermore, in one possible implementation, the operating modes of the frequency converter group include at least soft-start mode and grid management mode;

[0058] When the inverter group is operating in soft start mode, the first disconnect switch, the second disconnect switch, and the fourth disconnect switch are closed;

[0059] When the frequency converter group is operating in grid management mode, the first, second, and third disconnecting switches are closed. Furthermore, if motor operation is required in grid management mode, the fourth disconnecting switch is closed; if motor operation is not required in grid management mode, the fourth disconnecting switch is open.

[0060] Furthermore, when the frequency converter group is operating in soft-start mode, the third isolating switch is closed according to the motor's operating status, causing the motor to operate in grid-driven mode. Then, when the motor is operating in grid-driven mode, the third and fourth isolating switches are closed. Furthermore, when the motor is operating in grid-driven mode, if reactive power compensation to the power grid using the frequency converter group is required, the first and second isolating switches are closed; if reactive power compensation to the power grid using the frequency converter group is not required, the first and second isolating switches are open. The timing for closing the third isolating switch to allow the motor to operate in grid-driven mode is when the voltage at the motor's input terminal is equal to the voltage at the output terminal of the power grid.

[0061] exist Figure 2 Based on the system diagram of the motor control system shown, Figure 4 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 4 ,like Figure 4 As shown, in the motor control system provided in this embodiment, a substation, a power supply bus, and a transformer are provided between the output end of the power frequency grid and the input end of the frequency converter group; the input end of the power quality analysis module is provided between the substation and the output end of the power frequency grid, and / or, between the substation and the power supply bus, and / or, between the power supply bus and the transformer, and / or, between the transformer and the first disconnecting switch; wherein, the substation, the power supply bus, and the transformer are located within the factory area.

[0062] The input terminal of the power quality analysis module can be set between the output terminals of the substation and the power frequency grid, such as... Figure 4 The sampling point T0 shown can be set at the entrance end of the factory area; the input end of the power quality analysis module can be set between the substation and the power supply bus, such as... Figure 4 The sampling point T1 shown; the input terminal of the power quality analysis module can be set between the power supply bus and the transformer, such as Figure 4 The sampling point T2 shown; the input terminal of the power quality analysis module can be set between the transformer and the first disconnecting switch, such as... Figure 4 The sampling point T3 is shown.

[0063] exist Figure 2 Based on the system diagram of the motor control system shown, Figure 5 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 5 ,like Figure 5 As shown, in the motor control system provided in this embodiment, a substation and a power supply bus are provided between the output end of the power frequency grid and the input end of the frequency converter group; the input end of the power quality analysis module is provided between the substation and the output end of the power frequency grid, and / or between the substation and the power supply bus, and / or between the power supply bus and the first disconnecting switch; wherein, the substation and the power supply bus are located within the factory area.

[0064] The input terminal of the power quality analysis module can be set between the output terminals of the substation and the power frequency grid, such as... Figure 5 The sampling point T0 shown can be set at the entrance end of the factory area; the input end of the power quality analysis module can be set between the substation and the power supply bus, such as... Figure 5 The sampling point T1 shown; the input terminal of the power quality analysis module can be set between the power supply bus and the first disconnecting switch, such as Figure 5 The sampling point T4 is shown.

[0065] exist Figure 2 Based on the system diagram of the motor control system shown, Figure 6 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 6 ,like Figure 6 As shown, in the motor control system provided in this embodiment, a substation is provided between the output end of the power frequency grid and the input end of the frequency converter group; the input end of the power quality analysis module is provided between the substation and the output end of the power frequency grid, and / or between the substation and the first disconnecting switch; wherein, the substation is located within the factory area.

[0066] The input terminal of the power quality analysis module can be set between the substation and the output terminal of the power frequency grid, such as sampling point T0. Sampling point T0 can be set at the entrance of the factory area. The input terminal of the power quality analysis module can be set between the substation and the first disconnecting switch, such as sampling point T5.

[0067] In this embodiment, the location where the input terminal of the power quality analysis module is deployed enables the analysis and processing of power supply data to be completed near the sampling location of the power supply data, thereby obtaining power quality information and then sending the power quality information to the frequency converter group. This avoids the high latency problem of data sampling and data processing caused by direct sampling over long distances in large factories. Performing data processing and analysis first and then transmitting the data processing and analysis results reduces the requirements for communication transmission capabilities and achieves transmission compensation over longer distances.

[0068] Furthermore, the motor control system provided in this embodiment also includes a filter; wherein the filter includes an LCL filter and an LCR filter, the LCL filter and the LCR filter being connected in series; the frequency converter group is electrically connected to the LCL filter; and the LCR filter is electrically connected to the second disconnect switch.

[0069] The LCL filter is used to filter high-frequency harmonics in the voltage waveform and current waveform of the inverter output voltage and current waveform to obtain the first-stage filtered voltage and current. The LCR filter is used to filter mid- and low-frequency harmonics in the first-stage filtered voltage and current to obtain the second-stage filtered voltage and current, and inputs the second-stage filtered voltage and current to the motor, as well as the second-stage filtered reactive current to the power grid.

[0070] The LCL filter comprises a first inductor, a first capacitor, and a second inductor connected in sequence. The LCL filter forms a low-pass filter section through the first inductor (L1) and the first capacitor (C1), while the second inductor (L2) is used to suppress high-frequency components. The LCR filter comprises a second inductor, a second capacitor, and a resistor connected in sequence. The LCR filter forms a low-pass filter section through the second inductor (L3) and the second capacitor (C2), while the resistor (R1) is used to suppress resonance risks in the mid-to-low frequency range. When the LCR filter and the LCL filter are connected in series, both high-frequency and mid-to-low-frequency harmonics can be suppressed simultaneously, enabling the motor control system to adapt to more complex motor load conditions and power grid conditions.

[0071] In another possible implementation, the filter can be an LCL type filter, an LCR type filter, or an LC type filter.

[0072] In the motor control system provided in this application embodiment, the inverter group manages the power grid quality and keeps the inverter group running. This also solves the problem of accelerated aging of the inverter group caused by the inverter group being in a standby or power-off state for a long time after the soft start of the motor driven by the inverter group in the prior art. It avoids the risk of failure when the inverter group is restarted after being in a standby or power-off state for a long time.

[0073] Figure 7 A flowchart of a power grid management method provided in one embodiment of this application is shown below. Figure 7 As shown, the power grid management method provided in this embodiment is applied to... Figures 1 to 6 The motor control system shown in any embodiment, and the power grid management method provided in this embodiment, include the following steps:

[0074] Step S701: The power quality analysis module collects power supply data from the power frequency grid, obtains power quality information based on the power supply data, and sends the power quality information to the frequency converter group.

[0075] Step S702: Through the frequency converter group, reactive current is output to the power frequency grid according to the power supply quality information to compensate the reactive power of the power frequency grid to the preset compensation target.

[0076] In this embodiment, the motor control system includes a frequency converter group, a motor, and a power quality analysis module. The power quality analysis module monitors the power grid supply data in real time and generates power quality information. The frequency converter group receives the power quality information and outputs reactive current to the power frequency grid according to the power quality information to compensate the reactive power of the power frequency grid to a preset compensation target. This ensures that the reactive power of the power frequency grid approaches the preset compensation target in real time, stabilizes the voltage of the power frequency grid, improves the power factor of the power frequency grid, and enhances the power quality of the grid, thus solving the problem of poor power quality caused by factory power consumption.

[0077] When the frequency converter group executes step S702, the frequency converter group operates in the power grid management mode.

[0078] In one possible implementation, the inverter group includes an inverter that receives power quality information sent by a power quality analysis module. The power quality information is obtained by the power quality analysis module from the power supply data of the power frequency grid. The inverter outputs reactive current to the power frequency grid according to the power quality information to compensate the reactive power of the power frequency grid to a preset compensation target.

[0079] In one possible implementation, the inverter group includes at least two inverters, and the at least two inverters include one master inverter and at least one cooperating inverter; the preset compensation target includes a preset master control compensation target and a preset cooperating compensation target; Figure 1Based on the system diagram of the motor control system shown, Figure 8 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 7 ,like Figure 8 As shown, taking a frequency converter group including one main control frequency converter and two cooperating frequency converters as an example; the implementation steps of step S702 include:

[0080] Step S7021: Using the main control frequency converter, determine the quality compensation allocation information corresponding to each frequency converter based on the power supply quality information and the configuration information of the frequency converter group.

[0081] The quality compensation allocation information includes the quality compensation allocation information for the corresponding main control frequency converter and the quality compensation allocation information for each cooperative frequency converter. The quality compensation allocation information includes the reactive power compensation amount corresponding to the power supply quality information.

[0082] In some embodiments, the main control inverter calculates the total reactive power compensation required for the compensation point based on the power supply quality information, such as the total reactive power and harmonic power. Then, it determines the quality compensation allocation information based on the configuration information of the inverter group and the preset allocation rules. The preset allocation rules may be an average allocation method for online inverters, or an allocation based on the rated capacity ratio of online inverters to maintain the ratio of the operating load of each inverter to its rated capacity, or an allocation based on a pre-set allocation ratio.

[0083] Step S7022: The quality compensation allocation information is sent to each cooperating frequency converter through the main control frequency converter;

[0084] The main control frequency converter sends the quality compensation allocation information to each cooperating frequency converter, and each cooperating frequency converter receives the quality compensation allocation information.

[0085] Step S7023: Through the main control frequency converter and each cooperative frequency converter, reactive current is output to the power frequency grid according to the quality compensation allocation information to compensate the reactive power of the power frequency grid to the preset compensation target.

[0086] The main control frequency converter outputs reactive current to the power grid according to the quality compensation allocation information of the corresponding main control frequency converter in the quality compensation allocation strategy. In addition, each cooperative frequency converter outputs reactive current to the power grid according to the quality compensation allocation information of the corresponding cooperative frequency converter, so as to compensate the reactive power of the power grid to the preset compensation target.

[0087] In this embodiment, the main control inverter calculates and allocates the reactive power compensation amount to be borne by each inverter (main control inverter and cooperating inverter) based on the power supply quality information and the configuration information of the inverter group, forming quality compensation allocation information; the main control inverter and each cooperating inverter jointly output reactive current to the power frequency grid according to the quality compensation allocation information, and compensate the reactive power of the power frequency grid to the preset cooperating compensation target, so as to realize hierarchical and coordinated global compensation.

[0088] In another possible implementation, the inverter group includes at least two inverters; Figure 9 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 8 ,like Figure 9 As shown, taking a frequency converter group containing three frequency converters as an example; the implementation steps of steps S701 and S702 include:

[0089] Step S701A1: The power quality analysis module collects power supply data from the power frequency grid and obtains power quality information based on the power supply data.

[0090] Step S701A2: Using the power quality analysis module, the power quality compensation allocation information for each inverter in the inverter group is determined based on the power supply quality information and the inverter group configuration information.

[0091] In step S701A3, the power quality analysis module sends the power quality compensation allocation information to each inverter in the inverter group.

[0092] The quality compensation allocation information corresponds to the power supply quality information, and the quality compensation allocation information includes the reactive power compensation amount corresponding to the power supply quality information.

[0093] In step S702A2, each frequency converter in the frequency converter group outputs reactive current to the power grid according to the corresponding quality compensation allocation information, so as to compensate the reactive power of the power grid to the preset compensation target.

[0094] In this embodiment, the power quality analysis module uniformly calculates and allocates compensation amounts, enabling each frequency converter to collaboratively compensate for reactive power in the power frequency grid. The power quality analysis module calculates the total reactive power compensation amount based on power supply quality information, such as total reactive power and harmonic power. Then, it determines the quality compensation allocation information according to the configuration information of the frequency converter group and preset allocation rules. These preset allocation rules can be an average allocation method for online frequency converters, or allocation based on the rated capacity ratio of online frequency converters to maintain consistency between the operating load and rated capacity ratio of each frequency converter, or allocation based on a pre-set allocation ratio.

[0095] In another possible implementation, the inverter group includes at least two inverters, and the motor operation control system includes a transfer device; Figure 10 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 9 ;like Figure 10 As shown, the motor control system also includes a transfer device. Figure 10 Taking a frequency converter group comprising three frequency converters as an example, in some embodiments, the motor control system collects power supply data from the industrial frequency grid through a power quality analysis module, obtains power quality information based on the power supply data, and sends the power quality information to a relay device. The relay device then sends the power quality information to the frequency converter group. The main control frequency converter in the frequency converter group determines the corresponding quality compensation allocation information for each frequency converter in the group. Specifically, the main control frequency converter determines the quality compensation allocation information based on the power quality information and the configuration information of the frequency converter group, and sends the quality compensation allocation information to each cooperating frequency converter. Finally, the main control frequency converter and each cooperating frequency converter output reactive current to the industrial frequency grid according to the quality compensation allocation information to compensate the reactive power of the industrial frequency grid to a preset compensation target.

[0096] In another possible implementation, the inverter group includes at least two inverters, and the motor operation control system includes a transfer device; Figure 10 A schematic diagram of a motor control system provided in one embodiment of this application. Figure 9 ;like Figure 10 As shown, the motor control system also includes a transfer device. Figure 10 Taking a frequency converter group comprising three frequency converters as an example. In some embodiments, the quality compensation allocation information is determined by the transfer equipment, and the implementation steps of steps S701 and S702 include:

[0097] Step S701B1: The power quality analysis module collects power supply data from the power frequency grid, obtains power quality information based on the power supply data, and sends the power quality information to the relay equipment.

[0098] Step S701B2: Through the relay equipment, based on the power supply quality information and the configuration information of the frequency converter group, determine the quality compensation allocation information corresponding to each frequency converter in the frequency converter group, and send the quality compensation allocation information to each frequency converter in the frequency converter group.

[0099] The quality compensation allocation information corresponds to the power supply quality information, and the quality compensation allocation information includes the reactive power compensation amount corresponding to the power supply quality information.

[0100] In step S702B3, each frequency converter in the frequency converter group outputs reactive current to the power grid according to the corresponding quality compensation allocation information, so as to compensate the reactive power of the power grid to the preset compensation target.

[0101] In this embodiment, a relay device is used to determine the quality compensation allocation information, improving the flexibility of processing power quality-related data and compensation allocation amounts. The power quality analysis module is only responsible for collecting power supply data and generating power quality information, which is then sent to the relay device. Based on the power quality information and the configuration information of the frequency converter group, the relay device calculates and generates a quality compensation allocation strategy.

[0102] Furthermore, in one possible implementation, prior to step S701, the method provided in this application embodiment further includes:

[0103] By controlling the closing of the first isolating switch, the frequency converter group is put into standby preparation state;

[0104] In standby mode, the inverter group controls the second and fourth isolating switches to close, enabling the inverter group to operate in soft-start mode.

[0105] When the frequency converter group is operating in soft start mode, the third isolating switch is closed according to the motor's operating status, so that the motor can operate in grid-driven mode;

[0106] When the motor is running in grid-driven mode, the first and second disconnect switches are closed to allow the frequency converter to run in grid management mode.

[0107] The operation of controlling the closing of the first isolating switch includes manual control of closing and closing in response to a system start command.

[0108] The control of closing the third disconnect switch based on the motor's operating state includes: closing the third disconnect switch after the voltage at the motor's input terminal is equal to the voltage at the output terminal of the power grid. That is, the third disconnect switch is closed when the motor's operating state is such that the voltage at the motor's input terminal is equal to the voltage at the output terminal of the power grid. In some embodiments, the control of closing the third disconnect switch is implemented by a frequency converter group.

[0109] Furthermore, when the motor is running in grid-driven mode, keeping the first and second disconnect switches closed allows the inverter group to run in grid management mode, i.e., executing steps S701 and S702. In other words, when the motor is running in grid-driven mode and the inverter group is running in grid management mode, the first, second, third, and fourth disconnect switches are all kept closed.

[0110] Furthermore, in one possible implementation, prior to step S701, the method provided in this application embodiment further includes:

[0111] By controlling the closing of the first isolating switch, the frequency converter group is put into standby preparation state;

[0112] In standby mode, the inverter group is put into grid management mode by controlling the closing of the first disconnect switch, the second disconnect switch and the fourth disconnect switch.

[0113] The operation of controlling the closing of the first isolating switch includes manual control of closing and closing in response to a system start command.

[0114] The closing of the second and fourth disconnect switches is achieved through the control of the frequency converter group.

[0115] If it is not necessary to use the frequency converter group for soft start control of the motor, and the motor does not need to run, but only the frequency converter group is needed for grid management, the first disconnect switch can be closed to put the frequency converter group into standby preparation state. Then, the first disconnect switch can be kept closed, and the second and fourth disconnect switches can be closed to put the frequency converter group into grid management mode.

[0116] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0117] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0118] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0119] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0120] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0121] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0122] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0123] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0124] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0125] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A motor control system, characterized in that, Includes frequency converter units, motors, and power quality analysis modules; The frequency converter group includes one or at least two frequency converters, the input terminal of the frequency converter group is connected to the output terminal of the power frequency grid, and the output terminal of each frequency converter is connected to at least one of the motors; The input terminal of the motor is connected to the output terminal of the frequency converter group and the output terminal of the power frequency grid; The input terminal of the power quality analysis module is located between the input terminal of the inverter group and the output terminal of the power frequency grid. The power quality analysis module is connected to the inverter. The power quality analysis module is used to collect the power supply data of the power frequency grid, obtain power supply quality information based on the power supply data, and send the power supply quality information to the inverter group. The frequency converter group is used to output reactive current to the power frequency grid according to the power supply quality information, so as to compensate the reactive power of the power frequency grid to a preset compensation target.

2. The motor control system according to claim 1, characterized in that, It also includes a first disconnecting switch, a second disconnecting switch, a third disconnecting switch, and a fourth disconnecting switch; The input terminal of the frequency converter group is connected to the power grid through the first disconnecting switch, and the output terminal of the frequency converter group is connected to the input terminal of the motor through the second disconnecting switch and the fourth disconnecting switch; The input terminal of the motor is connected to the power grid through the fourth disconnect switch and the third disconnect switch; The input terminal of the power quality analysis module is located between the first disconnecting switch and the output terminal of the power frequency grid.

3. The motor control system according to claim 1, characterized in that, It also includes a transfer device, the output of which is connected to the power quality analysis module, and the transfer device is connected to the frequency converter group; The power quality analysis module is used to send the power quality information to the relay equipment; The relay equipment is used to send the received power quality information to the frequency converter group.

4. The motor control system according to claim 3, characterized in that, The inverter group includes at least two inverters; The relay equipment is used to determine a quality compensation allocation strategy based on the power supply quality information and the configuration information of the frequency converter group; allocate the power supply quality information according to the quality compensation allocation strategy to obtain the allocated power supply quality information; and send the allocated power supply quality information to the corresponding frequency converters. Each frequency converter is used to output reactive current to the power frequency grid according to the corresponding allocated power quality information, so as to compensate the reactive power of the power frequency grid to the preset compensation target.

5. The motor control system according to any one of claims 1 to 4, characterized in that, The power quality analysis module includes at least a voltage sampling unit, a current sampling unit, a data analysis unit, and a data transmission unit; The voltage sampling unit is used to collect voltage data from the power frequency grid; The current sampling unit is used to collect current data from the power frequency grid; The data analysis unit is used to analyze and obtain the power supply quality information based on the collected voltage data and current data; The data transmission unit is used to send the power quality information.

6. The motor control system according to claim 2, characterized in that, The operating modes of the frequency converter group include at least soft start mode and power grid management mode; When the inverter group is operating in the soft-start mode, the first disconnect switch, the second disconnect switch, and the fourth disconnect switch are closed. When the frequency converter group is operating in the power grid management mode, the first disconnect switch, the second disconnect switch, and the third disconnect switch are closed.

7. The motor control system according to claim 6, characterized in that, When the motor is operating in grid-driven mode, the third disconnect switch and the fourth disconnect switch are closed.

8. The motor control system according to claim 2, characterized in that, A substation, a power supply bus, and a transformer are provided between the output end of the power frequency grid and the input end of the frequency converter group. The input terminal of the power quality analysis module is located between the output terminals of the substation and the power frequency grid, and / or between the substation and the power supply bus, and / or between the power supply bus and the transformer, and / or between the transformer and the first disconnecting switch.

9. A power grid management method, characterized in that, Applied to the motor control system as described in any one of claims 1 to 8, the method comprises: The power quality analysis module collects power supply data from the power frequency grid, obtains power quality information based on the power supply data, and sends the power quality information to the frequency converter group. The inverter group outputs reactive current to the power grid based on the power quality information to compensate the reactive power of the power grid to a preset compensation target.

10. The method according to claim 9, characterized in that, The inverter group includes at least two inverters, and the at least two inverters include one main control inverter and at least one cooperative inverter; the preset compensation target includes a preset main control compensation target and a preset cooperative compensation target; The step of outputting reactive current to the power grid through the frequency converter group according to the power quality information to compensate the reactive power of the power grid to a preset compensation target includes: Based on the power supply quality information and the configuration information of the inverter group, the main control inverter determines the quality compensation allocation information for each inverter. The quality compensation allocation information is sent to each cooperating frequency converter through the main control frequency converter; The main control frequency converter and each cooperating frequency converter output reactive current to the power frequency grid according to the quality compensation allocation information, so as to compensate the reactive power of the power frequency grid to the preset compensation target.

11. The method according to claim 9, characterized in that, The inverter group includes at least two inverters; The process of collecting power supply data from the power frequency grid through the power quality analysis module, obtaining power quality information based on the power supply data, and sending the power quality information to the frequency converter group includes: The power quality analysis module collects power supply data from the industrial frequency grid and obtains power supply quality information based on the power supply data. Based on the power supply quality information and the configuration information of the inverter group, it determines the quality compensation allocation information corresponding to each inverter in the inverter group and sends the quality compensation allocation information to each inverter in the inverter group. The step of outputting reactive current to the power grid through the frequency converter group according to the power quality information to compensate the reactive power of the power grid to a preset compensation target includes: Each inverter in the inverter group outputs reactive current to the power grid according to the corresponding quality compensation allocation information, so as to compensate the reactive power of the power grid to the preset compensation target.

12. The method according to claim 9, characterized in that, The inverter group includes at least two inverters, and the motor control system also includes a transfer device; The process of collecting power supply data from the power frequency grid through the power quality analysis module, obtaining power quality information based on the power supply data, and sending the power quality information to the frequency converter group includes: The power quality analysis module collects power supply data from the power frequency grid, obtains power quality information based on the power supply data, and sends the power quality information to the relay equipment. The relay equipment determines the quality compensation allocation information for each inverter in the inverter group based on the power supply quality information and the configuration information of the inverter group; and sends the quality compensation allocation information to each inverter in the inverter group. The step of outputting reactive current to the power grid through the frequency converter group according to the power quality information to compensate the reactive power of the power grid to a preset compensation target includes: Each frequency converter receives the quality compensation allocation information sent by the transfer equipment. Each frequency converter outputs reactive current to the power grid according to the corresponding quality compensation allocation information, so as to compensate the reactive power of the power grid to the preset compensation target.

13. The method according to any one of claims 9 to 12, characterized in that, Before the step of collecting power supply data from the power frequency grid through the power quality analysis module, obtaining power quality information based on the power supply data, and sending the power quality information to the frequency converter group, the method further includes: By controlling the first isolating switch to close, the frequency converter group is put into standby preparation state; In the standby preparation state, the inverter group controls the second and fourth isolating switches to close, causing the inverter group to operate in soft start mode; When the inverter group is operating in the soft start mode, the third disconnect switch is closed according to the operating status of the motor, so that the motor operates in the grid-driven mode; When the motor is running in grid-driven mode, the first disconnect switch and the second disconnect switch are closed to allow the inverter group to run in grid management mode.

14. The method according to any one of claims 9 to 12, characterized in that, Before the step of collecting power supply data from the power frequency grid through the power quality analysis module, obtaining power quality information based on the power supply data, and sending the power quality information to the frequency converter group, the method further includes: By controlling the first isolating switch to close, the frequency converter group is put into standby preparation state; In the standby preparation state, the inverter group is operated in the power grid management mode by controlling the closing of the first disconnect switch, the second disconnect switch and the fourth disconnect switch.

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