Method and device for rapidly and automatically switching power frequency bypass when frequency converter breaks down

Abstract

The invention discloses a method for rapidly and automatically switching a power frequency bypass when a single motor frequency converter of a power plant breaks down. The method comprises the following steps that the voltage of a single motor end and the voltage of a power frequency bypass power supply are detected in real time; calculating an allowable switching phase angle difference between the single motor and the power frequency bypass power supply in real time and calculating an actual voltage phase angle difference in real time based on the impact tolerance condition of the single motor and the detected voltage at the end of the single motor; comparing the allowed switching phase angle difference with the actual voltage phase angle difference; if the actual voltage phase angle difference is smaller than or equal to the allowed switching phase angle difference, once the frequency converter breaks down, if the main power supply of the frequency converter is not disconnected with the single motor, the main power supply of the frequency converter is disconnected with the single motor, and meanwhile, the single motor is connected with the power frequency bypass power supply. According to the method, rapid switching can be ensured, the output of the motor is effectively ensured, and the influence on normal operation of a process system is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of power plants, and in particular to a method and device for quickly and automatically switching to a power frequency bypass when a frequency converter of a single motor in a power plant fails. Background Art

[0002] In order to improve the regulation efficiency of the process system and reduce energy consumption, frequency conversion equipment is often used in power stations to drive motors to adjust process parameters such as flow and pressure by changing the motor speed. This can reduce the loss of process equipment and reduce the power of the motor, effectively saving energy and reducing the power consumption rate of the plant. It is an energy-saving regulation method.

[0003] See also Figure 1 In the prior art, in order to ensure that the motor does not lose its operating output when the inverter fails but the motor is intact, the inverter with power frequency bypass wiring is often used. When the inverter is running normally, CB1 and CB2 are closed and CB3 is open. When the inverter fails, the operating power supply is switched from the inverter to the power frequency bypass, CB1 and CB2 are opened, and CB3 is closed.

[0004] At present, in the prior art, when the inverter fails and the power frequency bypass is switched manually, the time is relatively long. When the inverter fails and the power frequency bypass is switched automatically, the conventional practice is to fix the delay. In order to avoid the motor terminal voltage and the bypass power frequency voltage being reversed when the motor is idling, which may cause a large impact damage to the motor, after opening CB1 and CB2, the motor is delayed to wait for the motor to idle below the residual voltage (such as <20% UN), and then CB3 is automatically closed to reduce damage to the equipment. This delay is not short, and there is a risk of losing the motor output and reducing the capacity of the process system.

[0005] If a fixed phase angle difference blocking similar to the automatic switching of the plant power supply is used, it may be locked and lose the opportunity for rapid switching because the initial phase angle of the motor voltage and the phase angle of the power frequency bypass voltage are greatly different when the inverter fails. The locking phase angle difference of the plant power supply switching is generally not large (such as 20 degrees). Considering the group cluster motor starting on the bus, if the angle is too large, not only the total starting current will be large, but the bus voltage will also be low. Therefore, the switching method of the fixed phase angle difference blocking of the plant power supply is not suitable for the frequency conversion and power frequency switching conditions of a single motor.

[0006] Therefore, there is an urgent need in the art to develop a method and device for quickly and automatically switching to the power frequency bypass when the inverter of a single motor in a power plant fails, which can ensure rapid switching, effectively guarantee the output of the motor, and reduce the impact on the normal operation of the process system. Summary of the invention

[0007] The purpose of the present application is to provide a method and device for quickly and automatically switching to the power frequency bypass when the frequency converter of a single motor in a power plant fails, which can ensure rapid switching, effectively guarantee the output of the motor, and reduce the impact on the normal operation of the process system.

[0008] The present application provides a method for quickly and automatically switching to power frequency bypass when a frequency converter of a single motor in a power plant fails, characterized in that it comprises the following steps:

[0009] Step S1: Real-time detection of the voltage at the end of the single motor And the voltage of the power frequency bypass power supply The single motor is located downstream of the inverter main power supply and the industrial frequency bypass power supply, and the single motor is connected to the inverter main power supply; the inverter main power supply and the industrial frequency bypass power supply are connected in parallel;

[0010] Step S2: Based on the impact tolerance condition of the single motor and the voltage detected at the end of the single motor Calculate in real time the permissible switching phase angle difference between the single motor and the power frequency bypass power supply; wherein the withstand impact condition is that the voltage difference ΔU applied to the variable frequency motor will not exceed the rated voltage of the motor, and the voltage difference ΔU is the difference between the voltage of the power frequency bypass power supply and the terminal voltage of the single motor;

[0011] Step S3: Based on the voltage at the end of the single motor measured in real time And the voltage of the power frequency bypass power supply Calculate the actual voltage phase angle difference in real time;

[0012] Step S4: comparing the allowed switching phase angle difference with the actual voltage phase angle difference;

[0013] Step S5: If the actual voltage phase angle difference is less than or equal to the allowed switching phase angle difference, once the inverter fails, determine whether the inverter main power supply is disconnected from the single motor; if the inverter main power supply is not disconnected from the single motor, execute step S6; if the inverter main power supply is disconnected from the single motor, execute step S7;

[0014] Step S6: disconnecting the inverter main power supply from the single motor, and connecting the single motor to the industrial frequency bypass power supply;

[0015] Step S7: Connecting the single motor to the industrial frequency bypass power supply.

[0016] In another preferred embodiment, in step S2, based on the impact tolerance condition of the single motor and the detected voltage at the end of the single motor, and the voltage of the power frequency bypass power supply The allowable switching phase angle difference between the single motor and the industrial frequency bypass power supply is calculated in real time.

[0017] In another preferred embodiment, the voltage at the end of the single motor detected is used in step S2. The amplitude is also the voltage at the end of the single motor The absolute value of the power frequency bypass supply voltage The amplitude of the power frequency bypass power supply voltage The absolute value of .

[0018] In another preferred example, in step S2, when calculating the allowable switching phase angle difference, the voltage difference ΔU is assumed to be 1.

[0019] In another preferred example, the industrial frequency bypass power supply includes a bypass circuit breaker CB3, one end of the bypass circuit breaker CB3 is electrically connected to the single motor, and the other end of the bypass circuit breaker CB3 is electrically connected to the industrial frequency incoming power supply bus.

[0020] In another preferred embodiment, the allowable switching phase angle difference in step S2 is calculated by the following formula:

[0021]

[0022] Among them, Δδ is the allowable switching phase angle difference, ΔU is the difference between the voltage of the power frequency bypass power supply and the terminal voltage of the single motor, and U B is the voltage of the power frequency bypass power supply, U D is the voltage at the end of the single motor.

[0023] In another preferred embodiment, in the calculation of the allowable switching phase angle difference in step S2, U B It can be approximately 1 or it can be a measured value. Generally, the measured value is close to 1.

[0024] In another preferred example, step S51 is also included after step S4: if the actual voltage phase angle difference is greater than the allowable switching phase angle difference, once the inverter fails, only the inverter main power supply is disconnected from the single motor, and then the process returns to step S2.

[0025] In another preferred example, the inverter main power supply includes an inverter, an upstream circuit breaker CB1 and a downstream circuit breaker CB2, one end of the upstream circuit breaker CB1 is electrically connected to the inverter, and the other end is electrically connected to the industrial frequency power supply incoming bus; one end of the downstream circuit breaker CB2 is electrically connected to the inverter, and the other end is connected to the single motor.

[0026] In another preferred embodiment, CB1 and CB2 are opened, the frequency converter is disconnected, the motor is separated from the frequency converter and independently idles, the voltage at the motor terminals gradually decreases, and the frequency becomes smaller.

[0027] In another preferred example, when the upstream circuit breaker CB1 and the downstream circuit breaker CB2 are opened and the industrial frequency bypass power supply is connected to the single motor, the frequency converter is disconnected, one end of the bypass circuit breaker CB3 is connected to the motor that continues to idle, and the other end of the bypass circuit breaker CB3 is electrically connected to the industrial frequency incoming power supply bus.

[0028] In another preferred example, the industrial frequency bypass power supply is configured to be connected to the idling single motor when the frequency converter fails.

[0029] The present application also provides a device for quickly and automatically switching to power frequency bypass when a frequency converter of a single motor in a power plant fails, comprising:

[0030] a memory for storing computer executable instructions; and,

[0031] A processor, coupled to the memory, is configured to implement the steps in the above method when executing the computer executable instructions.

[0032] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, the steps in the above method are implemented.

[0033] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. It should be understood that the drawings described below are only some implementation examples of the present invention, and ordinary technicians in this field can also obtain other implementation examples based on these drawings without paying creative work.

[0035] Figure 1 A flow chart of a method for quickly and automatically switching to power frequency bypass when a frequency converter fails according to an embodiment of the present application;

[0036] Figure 2 It is the wiring of the motor frequency conversion belt power frequency bypass;

[0037] Figure 3 It is an equivalent circuit diagram of the motor and the power frequency bypass power supply when CB1 and CB2 of the inverter main power supply are disconnected according to the implementation mode of the present application;

[0038] Figure 4 is a schematic diagram of an allowable switching phase angle difference between a single motor and an industrial frequency bypass power supply according to an embodiment of the present application;

[0039] Figure 5 The present invention is a flow chart of a method for quickly and automatically switching to power frequency bypass when a frequency converter fails according to an embodiment. DETAILED DESCRIPTION

[0040] Through extensive and in-depth research, the inventors have developed for the first time a method and device for quickly and automatically switching to the industrial frequency bypass when the frequency converter of a single motor in a power plant fails. The method utilizes the low terminal voltage of the variable frequency running motor and the small impact of the full-voltage starting of a single motor on the motor and the power consumption of the power station. Under the condition of impact tolerance, the method calculates the allowable switching phase angle difference between the variable frequency motor and the industrial frequency bypass in real time, captures the switching opportunity, and promotes rapid switching.

[0041] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0042] the term

[0043] As used herein, "inverter motor" and "motor" are used interchangeably;

[0044] As used herein, "power frequency bypass" and "power frequency bypass power supply" are used interchangeably;

[0045] It should be noted that in the application documents of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one" do not exclude the existence of other identical elements in the process, method, article or device including the elements. In the application documents of this patent, if it is mentioned that an action is performed according to an element, it means that the action is performed at least according to the element, which includes two situations: performing the action only according to the element, and performing the action according to the element and other elements. Expressions such as multiple, multiple, and multiple include 2, 2 times, 2 kinds, and more than 2, more than 2 times, and more than 2 kinds.

[0046] In the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0047] The present invention has at least one of the following advantages

[0048] (a) The method of quickly and automatically switching to the power frequency bypass when the frequency converter fails in the present application fully utilizes the characteristics that the variable frequency motor is not running at the rated voltage, and the full voltage starting of a single motor has little impact on the factory power supply. Based on the impact that the motor is allowed to withstand, the allowable phase angle difference of switching to the power frequency bypass when the frequency converter fails is captured in real time to ensure fast switching, effectively guarantee the output of the motor, and reduce the impact on the normal operation of the process system;

[0049] (b) The method of quickly and automatically switching to the power frequency bypass when the frequency converter fails in the present application calculates the allowable switching phase angle difference according to the impact conditions allowed by the full voltage (rated voltage) start of the motor when the frequency converter motor is not running at the rated voltage. Within a wide initial phase angle range, as long as the allowable conditions are met, CB1 and CB2 can be separated and CB3 can be closed at the same time, which can avoid the impact on the equipment and can capture the switching conditions more quickly than fixed delay or fixed phase angle difference locking, and implement fast switching;

[0050] (c) The method of the present application for quickly and automatically switching to the power frequency bypass when the inverter fails can make full use of the real-time calculation advantage of the larger switching phase angle difference allowed by the voltage of the idling motor continuing to drop once the measured initial phase angle difference is too large to complete the switching immediately, so as to capture the opportunity for another switching, implement the switching as soon as possible, and improve the switching success rate;

[0051] (d) The method of quickly and automatically switching to industrial frequency bypass when the frequency converter fails in the present application is also applicable to power failure switching of a single motor powered by multiple power sources.

[0052] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0053] See also Figure 1 The first embodiment of the present application relates to a method for quickly and automatically switching to power frequency bypass when a frequency converter of a single motor in a power plant fails. The method comprises the following steps:

[0054] Step S1: Real-time detection of the voltage at the end of the single motor And the voltage of the power frequency bypass power supply The single motor is located downstream of the inverter main power supply and the industrial frequency bypass power supply, and the single motor is connected to the inverter main power supply; the inverter main power supply and the industrial frequency bypass power supply are connected in parallel;

[0055] Step S2: Based on the impact tolerance condition of the single motor and the voltage detected at the end of the single motor The amplitude or absolute value or size, and the power frequency bypass power supply voltage The amplitude or absolute value or size of the switching phase angle difference between the single motor and the power frequency bypass power supply is calculated in real time; wherein the withstand impact condition is that the voltage difference ΔU applied to the variable frequency motor will not exceed the rated voltage of the motor, and the voltage difference ΔU is the difference between the voltage of the power frequency bypass power supply and the terminal voltage of the single motor;

[0056] Step S3: Based on the voltage at the end of the single motor measured in real time And the voltage of the power frequency bypass power supply Calculate the actual voltage phase angle difference in real time;

[0057] Step S4: comparing the allowed switching phase angle difference with the actual voltage phase angle difference;

[0058] Step S5: If the actual voltage phase angle difference is less than or equal to the allowed switching phase angle difference, once the inverter fails, determine whether the inverter main power supply is disconnected from the single motor; if the inverter main power supply is not disconnected from the single motor, execute step S6; if the inverter main power supply is disconnected from the single motor, execute step S7;

[0059] Step S6: disconnecting the inverter main power supply from the single motor, and connecting the single motor to the industrial frequency bypass power supply;

[0060] Step S7: Connecting the single motor to the industrial frequency bypass power supply.

[0061] Preferably, after step S4, step S51 is further included: if the actual voltage phase angle difference is greater than the allowable switching phase angle difference, once the inverter fails, only the inverter main power supply is disconnected from the single motor, and then the process returns to step S2. Since the single motor is idling at this time, the voltage of the single motor continues to drop, and the allowable switching phase angle difference is calculated again in real time (due to the voltage drop at the motor end, the allowable switching phase angle difference will be larger), and the opportunity for another switching is captured, and the switching is performed as soon as possible until it is successful, thereby improving the switching success rate.

[0062] Preferably, the allowable switching phase angle difference in step S2 is calculated by the following formula:

[0063]

[0064] Among them, Δδ is the allowable switching phase angle difference, ΔU is the size or amplitude of the difference between the voltage of the power frequency bypass power supply and the terminal voltage of the single motor, and U B is the voltage or amplitude of the power frequency bypass power supply, U D is the voltage size or amplitude at the end of the single motor.

[0065] Preferably, the voltage difference ΔU is assumed to be 1.

[0066] Preferably, U B It is assumed to be 1, because the factory power design must meet the full voltage starting of a single motor without major impact, that is, the full voltage starting of a single motor does not affect the power frequency bypass bus voltage, so U B The per-unit value is approximately 1. In other embodiments, U can also be calculated based on the actual detected voltage. B .

[0067] Preferably, the industrial frequency bypass power supply includes a bypass circuit breaker CB3, one end of the bypass circuit breaker CB3 is electrically connected to the single motor, and the other end of the bypass circuit breaker CB3 is electrically connected to the industrial frequency incoming power supply bus.

[0068] The inverter main power supply includes an inverter, an upstream circuit breaker CB1 and a downstream circuit breaker CB2. One end of the upstream circuit breaker CB1 is electrically connected to the inverter, and the other end is electrically connected to the industrial frequency power supply incoming bus; one end of the downstream circuit breaker CB2 is electrically connected to the inverter, and the other end is connected to the single motor.

[0069] When CB1 and CB2 are opened, the inverter is disconnected, the motor is separated from the inverter and independently idles, the voltage at the motor terminals gradually decreases, and the frequency becomes smaller.

[0070] In other words, when the upstream circuit breaker CB1 and the downstream circuit breaker CB2 are opened and the power frequency bypass power supply is connected to the single motor, the frequency converter is disconnected, one end of the bypass circuit breaker CB3 is connected to the motor that continues to idle, and the other end of the bypass circuit breaker CB3 is electrically connected to the power frequency incoming power bus. That is, the power frequency bypass power supply is configured to be connected to the idle single motor when the frequency converter fails.

[0071] Preferably, a controller is further included, wherein the controller is configured to execute closing and opening operations of the circuit breakers CB1, CB2 and CB3 upon receiving external information on whether the frequency converter is faulty.

[0072] Example 1

[0073] In order to better understand the technical solution of the present application, a specific example is provided below for illustration. The details listed in the example are mainly for ease of understanding and are not intended to limit the scope of protection of the present application.

[0074] When the inverter is running, the output voltage and frequency are not rated parameters. Different operating conditions are different. When the frequency is high, the voltage is high, and when the frequency is low, the voltage is low, so as to avoid overexcitation and overheating of the motor. When the motor voltage is lower than the rated voltage, even if the phase angle difference between the motor voltage and the bypass power frequency voltage is slightly larger, the impact on the equipment is smaller than that at the rated voltage. This embodiment provides a method for quickly and automatically switching to the power frequency bypass by capturing the permissible conditions for tolerating the impact.

[0075] The design of the power supply for power stations allows a single motor to start at full voltage, which will not have a big impact on the bus voltage and can be tolerated by related equipment. Therefore, this application does not use a fixed delay or a fixed phase difference lock, but calculates the allowable switching phase difference in real time based on the voltage and frequency of the running motor. The phase difference is based on the impact that the equipment can tolerate. When the inverter fails, as long as the phase difference between the motor outlet and the power frequency bypass is within the allowable switching phase difference range, CB3 can be automatically closed immediately while CB1 and CB2 are opened, and the switch to the power frequency bypass can be quickly switched in a very short time (see Figure 2 ).

[0076] The impact conditions that the motor can withstand are: the voltage difference applied to the motor will not exceed the rated voltage of the motor; the current will not exceed the current starting multiple when the motor is started at full voltage and zero speed; it will not cause false operation of protection such as motor quick trip.

[0077] When CB1 and CB2 are open, see Figure 3 , the equivalent circuit diagram of the motor and the industrial frequency bypass power supply is as follows:

[0078] is the power frequency bypass voltage vector, is the motor voltage vector;

[0079] is the voltage difference vector applied to the motor and the power supply;

[0080] X B With X D They are the equivalent impedance per unit value of the industrial frequency bypass power supply system and the motor respectively.

[0081] I under voltage difference ch The inrush current is as follows:

[0082]

[0083] The equivalent impedance of a single motor is much larger than the equivalent impedance of the power frequency bypass power supply system. To simplify the calculation, ignore X. B The starting inrush current (per unit value) when the motor is started at full voltage (rated voltage) is (The rated voltage is the reference value, so the unit value of the rated voltage is 1). ch =I ch启动 , that is, in order to ensure that the impact current does not exceed the starting current of a single motor when it is started at full voltage, ΔU = 1.

[0084] The voltage difference vector is:

[0085] See also Figure 4 , the per unit pressure difference is:

[0086] Δδ is and The phase angle difference between them. Then:

[0087]

[0088] When a single motor is started at full voltage, it does not affect the power frequency bypass bus voltage, so U B The per-unit value is approximately 1; the impact condition that the motor can withstand is: the voltage difference applied to the motor will not exceed the rated voltage of the motor, so the per-unit value of the voltage difference ΔU is allowed to be 1. When the per-unit value of the voltage difference is allowed to be 1, the motor starting current will not exceed the normal starting current multiple, and will not cause the motor to trip or other protection malfunctions.

[0089] After simplification, the allowable switching phase angle difference that the motor can tolerate is:

[0090]

[0091] When the inverter runs at the industrial frequency, the motor voltage U D When it is 1, the allowed phase angle difference is

[0092]

[0093] When the inverter runs at 70% fn, the motor voltage U D When 0.7 is taken, the allowed phase angle difference is

[0094]

[0095] Close to 70 degrees.

[0096] The allowable phase angle difference calculated according to the withstand impulse condition is large. The lower the motor voltage, the larger the allowable phase angle difference. Real-time calculation allows the power frequency bypass circuit breaker to be closed within a wide variable window range, thereby improving the success rate of rapid switching. Considering the closing time of the circuit breaker, and the closing time is slightly longer than the opening time, the power frequency bypass power supply will be closed at a smaller phase angle difference. See Figure 5 , the specific steps are as follows:

[0097] Step S100: Calculate in real time the permissible switching phase angle difference between the variable frequency running motor and the industrial frequency bypass power supply;

[0098] Step 200: determining whether the measured phase angle difference between the motor end and the power frequency bypass power supply is within the allowable value range;

[0099] Step S300: If it is within the allowable value, once the inverter fails, determine whether CB1 and CB2 are open. If both are closed, proceed to step S400 to open CB1 and CB2 at the same time and close CB3; if both CB1 and CB2 are open, proceed to step S600 to close CB3.

[0100] Step S500: If the initial phase angle difference is greater than the allowable value, once the inverter fails, only CB1 and CB2 are separated. Then, in step S100, the voltage and phase angle of the continuously idling motor are combined to calculate the allowable phase angle difference between the power frequency bypass power supply in real time to capture the next closing opportunity. Once the measured phase angle difference is within the allowable value range after step S200, CB3 is closed after steps S300 and S600.

[0101] In other embodiments, when calculating the allowable phase angle difference, such as U B The per-unit value is approximately 1, or the actual voltage per-unit value collected can be used. B , but you can also input the specific impedance per unit value instead of ignoring it.

[0102] The second embodiment of the present application relates to a device for quickly and automatically switching to a power frequency bypass when a frequency converter of a single motor in a power plant fails, the device comprising:

[0103] A detection module configured to detect the voltage at the end of a single motor in real time And the voltage of the power frequency bypass power supply

[0104] A calculation module, the calculation module is configured to calculate the voltage at the end of the single motor based on the voltage at the end of the single motor measured by the detection module The amplitude of the single motor is used to calculate the allowable switching phase angle difference between the single motor and the power frequency bypass power supply in real time; at the same time, based on the voltage at the end of the single motor measured by the detection module and the voltage of the power frequency bypass power supply Calculate the actual voltage phase angle difference between two voltage vectors in real time;

[0105] A comparison and judgment module, wherein the comparison module is configured to compare the allowed switching phase angle difference with the actual voltage phase angle difference, and judge whether the actual voltage phase angle difference is less than or equal to the allowed switching phase angle difference;

[0106] A judgment execution module, wherein the execution module is configured to judge whether the inverter main power supply is disconnected from the single motor when the inverter fails if the actual voltage phase angle difference is less than or equal to the allowable switching phase angle difference; if the inverter main power supply is not disconnected from the single motor, the inverter main power supply is disconnected from the single motor and the single motor is connected to the industrial frequency bypass power supply at the same time; if the inverter main power supply has been disconnected from the single motor, the single motor is connected to the industrial frequency bypass power supply.

[0107] In another preferred example, it further includes a transmission module, and the transmission module is configured to transmit information on whether the frequency converter is faulty to the judgment execution module.

[0108] The first implementation manner is a method implementation manner corresponding to the present implementation manner. The technical details in the first implementation manner can be applied to the present implementation manner, and the technical details in the present implementation manner can also be applied to the first implementation manner.

[0109] It should be noted that those skilled in the art should understand that the implementation functions of each module shown in the implementation of the device for quickly and automatically switching to the power frequency bypass when a single motor frequency converter of a power plant fails can be understood by referring to the relevant description of the method for quickly and automatically switching to the power frequency bypass when a single motor frequency converter of a power plant fails. The functions of each module shown in the implementation of the device for quickly and automatically switching to the power frequency bypass when a single motor frequency converter of a power plant fails can be implemented by a program (executable instruction) running on a processor, or by a specific logic circuit. The embodiment of the present application, if the device for quickly and automatically switching to the power frequency bypass when a single motor frequency converter of a power plant fails is implemented in the form of a software function module and sold or used as an independent product, can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiment of the present application can be essentially or in other words, the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk or an optical disk, and other media that can store program codes. Thus, the embodiments of the present application are not limited to any specific combination of hardware and software.

[0110] Accordingly, the embodiments of the present application also provide a computer-readable storage medium, in which computer executable instructions are stored, and when the computer executable instructions are executed by the processor, the various method embodiments of the present application are implemented. Computer-readable storage media include permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be a computer-readable instruction, a data structure, a module of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable storage media does not include temporary computer-readable media (transitory media), such as modulated data signals and carriers.

[0111] In addition, the embodiment of the present application also provides a device for quickly and automatically switching to the power frequency bypass when a single motor inverter of a power plant fails, which includes a memory for storing computer executable instructions, and a processor; the processor is used to implement the steps in the above-mentioned method implementation when executing the computer executable instructions in the memory. Among them, the processor can be a central processing unit (Central Processing Unit, referred to as "CPU"), a graphic processor (Graphic Processing Unit, referred to as "GPU"), a digital signal processor (Digital Signal Processor, referred to as "DSP"), a microcontroller unit (Microcontroller Unit, referred to as "MCU"), a neural network processor (referred to as "NPU"), an application specific integrated circuit (Application Specific Integrated Circuit, referred to as "ASIC"), a field programmable gate array (Field Programmable Gate Array, referred to as "FPGA") or other programmable logic devices, etc. The aforementioned memory can be a read-only memory (read-only memory, referred to as "ROM"), a random access memory (random access memory, referred to as "RAM"), a flash memory (Flash), a hard disk or a solid state drive, etc. The steps of the method disclosed in each embodiment of the present invention can be directly implemented as being executed by a hardware processor, or can be implemented by a combination of hardware and software modules in the processor.

[0112] The serial numbers used in describing the steps of the method do not themselves constitute any limitation on the order of these steps. For example, the step with a larger serial number does not necessarily have to be executed after the step with a smaller serial number. The step with a larger serial number may be executed first and then the step with a smaller serial number. They may also be executed in parallel, as long as this execution order is reasonable for those skilled in the art. For another example, multiple steps with consecutive serial numbers (e.g., step 101, step 102, step 103, etc.) do not limit other steps that can be executed in between. For example, there may be other steps between step 101 and step 102.

[0113] This specification includes combinations of the various embodiments described herein. Individual references to embodiments (e.g., "one embodiment" or "some embodiments" or "preferred embodiments"); however, these embodiments are not mutually exclusive unless indicated as mutually exclusive or it is clear to a person skilled in the art that they are mutually exclusive. It should be noted that the word "or" is used in this specification in a non-exclusive sense unless the context clearly indicates or requires otherwise.

[0114] All documents mentioned in this specification are considered to be included in the disclosure of this application as a whole, so that they can be used as a basis for modification when necessary. In addition, it should be understood that the above is only a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of one or more embodiments of this specification.

[0115] In some cases, the actions or steps described in the claims may be performed in a different order than in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0116] A large number of technical features are recorded in the specification of this application, which are distributed in various technical solutions. If all possible combinations of technical features of this application (i.e., technical solutions) are to be listed, the specification will be too long. In order to avoid this problem, the various technical features disclosed in the above-mentioned invention content of this application, the various technical features disclosed in the various embodiments and examples below, and the various technical features disclosed in the accompanying drawings can be freely combined with each other to form various new technical solutions (these technical solutions are all deemed to have been recorded in this specification), unless the combination of such technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed, and features C and D are equivalent technical means that play the same role. Technically, only one can be used, and it is impossible to use them at the same time. Feature E can be combined with feature C technically. Then, the solution of A+B+C+D should not be deemed to have been recorded because it is technically infeasible, and the solution of A+B+C+E should be deemed to have been recorded.

[0117] All documents mentioned in this application are considered to be included in the disclosure of this application as a whole, so that they can be used as the basis for modification when necessary. In addition, it should be understood that after reading the above disclosure of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A method for quickly and automatically switching to power frequency bypass when the inverter of a single motor in a power plant fails. It is characterized in that The following steps are involved: Step S1: Real-time detection of the voltage at the end of the single motor And the voltage of the power frequency bypass power supply The single motor is located downstream of the inverter main power supply and the industrial frequency bypass power supply, and the single motor is connected to the inverter main power supply; the inverter main power supply and the industrial frequency bypass power supply are connected in parallel; Step S2: Based on the impact tolerance condition of the single motor and the voltage detected at the end of the single motor Calculate in real time the permissible switching phase angle difference between the single motor and the power frequency bypass power supply; wherein the withstand impact condition is that the voltage difference ΔU applied to the variable frequency motor will not exceed the rated voltage of the motor, and the voltage difference ΔU is the difference between the voltage of the power frequency bypass power supply and the terminal voltage of the single motor; Step S3: Based on the voltage at the end of the single motor measured in real time And the voltage of the power frequency bypass power supply Calculate the actual voltage phase angle difference in real time; Step S4: comparing the allowed switching phase angle difference with the actual voltage phase angle difference; Step S5: If the actual voltage phase angle difference is less than or equal to the allowed switching phase angle difference, once the inverter fails, determine whether the inverter main power supply is disconnected from the single motor; if the inverter main power supply is not disconnected from the single motor, execute step S6; if the inverter main power supply is disconnected from the single motor, execute step S7; Step S6: disconnecting the inverter main power supply from the single motor, and connecting the single motor to the industrial frequency bypass power supply; Step S7: Connecting the single motor to the industrial frequency bypass power supply.

2. The method for quickly and automatically switching the power frequency bypass as claimed in claim 1, It is characterized in that In step S2 , when calculating the allowable switching phase angle difference, the voltage difference ΔU is assumed to be 1.

3. The method for quickly and automatically switching the power frequency bypass as claimed in claim 2, It is characterized in that The industrial frequency bypass power supply includes a bypass circuit breaker CB3, one end of the bypass circuit breaker CB3 is electrically connected to the single motor, and the other end of the bypass circuit breaker CB3 is electrically connected to the industrial frequency incoming power supply bus.

4. The method for quickly and automatically switching the power frequency bypass as claimed in claim 3, It is characterized in that The allowed switching phase angle difference in step S2 is calculated by the following formula: Among them, Δδ is the allowable switching phase angle difference, ΔU is the difference between the voltage of the power frequency bypass power supply and the terminal voltage of the single motor, and U B is the voltage of the power frequency bypass power supply, U D is the voltage at the end of the single motor.

5. The method for quickly and automatically switching the power frequency bypass as claimed in claim 4, It is characterized in that In the calculation of the permissible switching phase angle difference in step S2, U B It can be approximately taken as 1 or the actual measured value.

6. The method for quickly and automatically switching the power frequency bypass as claimed in claim 5, It is characterized in that After step S4, the method further includes step S51: if the actual voltage phase angle difference is greater than the allowable switching phase angle difference, once the inverter fails, only the inverter main power supply is disconnected from the single motor, and then the method returns to step S2.

7. The method for quickly and automatically switching the power frequency bypass as claimed in claim 6, It is characterized in that The inverter main power supply includes an inverter, an upstream circuit breaker CB1 and a downstream circuit breaker CB2. One end of the upstream circuit breaker CB1 is electrically connected to the inverter, and the other end is electrically connected to the industrial frequency power supply incoming bus; one end of the downstream circuit breaker CB2 is electrically connected to the inverter, and the other end is connected to the single motor.

8. The method for quickly and automatically switching the power frequency bypass as claimed in claim 7, It is characterized in that When the upstream circuit breaker CB1 and the downstream circuit breaker CB2 are opened and the industrial frequency bypass power supply is connected to the single motor, the frequency converter is disconnected, one end of the bypass circuit breaker CB3 is connected to the motor that continues to idle, and the other end of the bypass circuit breaker CB3 is electrically connected to the industrial frequency incoming power supply bus.

9. A device for quickly and automatically switching to power frequency bypass when a single motor inverter in a power plant fails. It is characterized in that include: A memory for storing computer executable instructions; as well as, A processor, coupled to the memory, configured to implement the steps of the method according to any one of claims 1 to 8 when executing the computer executable instructions.

10. A computer-readable storage medium, It is characterized in that The computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, the steps in the method according to any one of claims 1 to 8 are implemented.

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