Active control method, system and equipment for grid-side harmonic waves and medium

Abstract

The invention relates to the field of electric locomotives, and provides an active control method, system and device for grid-side harmonic waves and a medium, and the method comprises the steps: collecting a grid-side voltage signal, carrying out the de-noising processing, carrying out the BPF filtering calculation and harmonic component detection of the processed voltage signal, and obtaining the grid-side harmonic waves; generating a fault signal according to an actual working condition in response to the condition that the network-side harmonic wave exceeds a threshold value; switching the switching frequency of the four quadrants from 450Hz to 750Hz through the TCU of each axis, and continuously carrying out BPF filtering calculation and harmonic component detection; and in response to the network side harmonic recovery, when the detection signal of each axis is at a low level, switching the switching frequency of the four quadrants from 750Hz to 550Hz through the TCU of each axis. According to the invention, the higher harmonic component generated by the locomotive deviates from the frequency band of the grid-side resonance, so that the Jp current, primary side current THD and secondary side current THD of the locomotive are reduced.

Description

Technical Field

[0001] The present invention relates to the field of electric locomotives, and in particular to an active control method, system, equipment and medium for grid-side harmonics. Background Art

[0002] Harmonics refer to non-sinusoidal waveform components of voltage or current in the power system, whose frequency is an integer multiple of the fundamental frequency. On the electric locomotive grid side, harmonics are mainly generated by non-linear loads, such as rectifiers, inverters and other power electronic devices. When the current flows through these non-linear loads, it is not linearly related to the applied voltage, thus forming a non-sinusoidal current, that is, harmonics are generated in the circuit.

[0003] The order and amplitude of the grid-side harmonics of electric locomotives depend on the type and working state of the power electronic devices. Generally speaking, the rectifier mainly produces odd harmonics, such as the 3rd, 5th, 7th, etc., and the amplitude of the harmonics decreases rapidly as the order of the harmonics increases.

[0004] During the operation of electric locomotives, their loads are moving and changing rapidly, so the harmonics generated are also time-varying. This time-varying property makes the treatment of harmonic pollution more complicated. The emergence of harmonic currents and harmonic voltages will pollute the public power grid and reduce the quality of power supply. Harmonics may increase the voltage drop of lines and transformers, causing power supply voltage fluctuations; at the same time, harmonics will also increase the loss of the core transmission equipment of electric locomotives, reduce equipment efficiency and service life, and affect the normal and safe operation of locomotives.

[0005] In the prior art, relevant measures have been taken for substations. Generally, two measures are adopted: adding active filtering and passive filtering. Passive filters are mainly used for specific harmonics in the system, such as the more harmful 3rd and 5th harmonics, and are composed of L and C series to form a resonant filter. Compared with the passive type, the active filter has a significant advantage, that is, there is no need to use multiple passive filters of specific frequencies in the system, but only one filter can be used to filter any harmonic order, and it will not resonate with the system, which is very suitable for railway electrification systems.

[0006] It is also possible to consider reducing the impact of harmonics on the system by optimizing the structural layout and parameter settings of the electric locomotive traction power supply system, such as reasonably setting the location and capacity of the traction substation and optimizing the impedance matching of the traction network.

[0007] However, due to the current limitations of control technology and the application of high-power components, active filters are still in the research and development stage and have not been promoted. The railway line has a large span and there are many substations along the line. If the location and capacity of the substations need to be reallocated, or multiple passive filters with specific powers need to be added, the operating and maintenance costs of the relevant substations will increase dramatically, and the impact of occasional high-order harmonics cannot be avoided.

[0008] The existing technology adds harmonic filters in electric locomotives, such as LC tuned filters, active power filters, etc. These filters can absorb or offset the harmonic components in the power grid, thereby reducing the harmonic content. However, the voltage level is high, so the size and weight of the filter are large, and the harmonics will be brought to other locomotives through the contact network. Therefore, the capacity must be fully considered during the design, but due to the limitations of weight and volume, it is very difficult to actually implement it on the locomotive.

[0009] Therefore, in order to reduce the impact of grid-side harmonics on electric locomotives, grid-side harmonics must be controlled accordingly. Summary of the invention

[0010] Based on the above objectives, the present invention proposes a method for active control of grid-side harmonics, comprising: Collect the grid-side voltage signal and perform denoising processing, and perform BPF filtering calculation and harmonic component detection on the processed voltage signal to obtain grid-side harmonics; In response to the grid-side harmonic exceeding a threshold, generating a fault signal according to actual operating conditions; The switching frequency of the four quadrants is switched from 450Hz to 750Hz through the TCU of each axis, and BPF filtering calculation and harmonic component detection are continuously performed; In response to the grid-side harmonic recovery, when the detection signals of each axis are at a low level, the switching frequency of the four quadrants is switched back from 750 Hz to 550 Hz through the TCU of each axis.

[0011] In some embodiments, the steps of filtering the processed voltage signal through BPF and detecting harmonic components include: Perform BPF calculations on the third harmonic frequency, the fifth harmonic frequency, and the sum of the harmonic frequencies of 750Hz-3750Hz respectively to obtain filtered signals within each frequency range; The amplitude of the filtered signal is calculated by the root mean square value, and the amplitude is extracted as the corresponding harmonic component.

[0012] In some embodiments, in response to the grid-side harmonic exceeding a threshold, the step of generating a fault signal comprises: In response to detecting that the low-order harmonics or high-order harmonics exceed the threshold, the TCU of the detection shaft generates a fault signal and uploads the fault signal to the TCMS; TCMS receives the signal and outputs four-quadrant frequency switching instructions to the TCU of each axis.

[0013] In some embodiments, in response to detecting that a low-order harmonic or a high-order harmonic exceeds a threshold, the steps are: Compare the corresponding 3rd harmonic component and 5th harmonic component with the set threshold value; When the threshold is exceeded, the corresponding low-order harmonic components are output; Compare the sum of the 750Hz-3750Hz harmonic components with the set threshold; When the threshold is exceeded, the corresponding high-order harmonic components are output.

[0014] In some embodiments, the BPF filtering includes: For the third harmonic frequency, set a BPF with a center frequency of 150Hz; For the 5th harmonic frequency, set a BPF with a center frequency of 250Hz; For the harmonic frequencies of 750 Hz to 3750 Hz, a BPF with a bandwidth covering the frequency range is set.

[0015] In some embodiments, the step of switching the switching frequency of the four quadrants from 450 Hz to 750 Hz through the TCU of each axis includes: Enter TCU; In the parameter setting of TCU, obtain the parameters related to the switching frequency of the four-quadrant rectifier and inverter, and modify the parameter value from 450Hz to 750Hz; The TCU operates at the modified switching frequency, and an oscilloscope is used to observe the current waveforms of the four-quadrant rectifier and inverter.

[0016] In some embodiments, in response to the grid-side harmonic exceeding a threshold, generating a fault signal according to actual working conditions further includes: When the actual working condition is parking and only the APU is working, the four-quadrant switching frequency controlled by the fault signal is 1100 Hz.

[0017] The present invention proposes a system for active control of grid-side harmonics, comprising: a detection module configured to collect grid-side voltage signals and perform denoising processing, and to obtain grid-side harmonics by performing BPF filtering calculation and harmonic component detection on the processed voltage signals; a fault module configured to generate a fault signal in response to the grid-side harmonic exceeding a threshold value according to actual working conditions; A switching module is configured to switch the switching frequency of the four quadrants from 450 Hz to 750 Hz through the TCU of each axis, and continuously perform BPF filtering calculation and harmonic component detection; The recovery module is configured to respond to the grid-side harmonic recovery, and when the detection signals of each axis are at a low level, the switching frequency of the four quadrants is switched back to 550 Hz from 750 Hz through the TCU of each axis.

[0018] The present invention provides a computer device, comprising: At least one processor; and a memory, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the program, the steps of the method for actively controlling grid-side harmonics are performed.

[0019] The present invention proposes a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for actively controlling grid-side harmonics are executed.

[0020] The present invention has at least the following beneficial technical effects: The present invention proposes a method, system, device and medium for active control of grid-side harmonics, the method comprising: collecting grid-side voltage signals and denoising them, and obtaining grid-side harmonics by BPF filtering calculation and harmonic component detection of the processed voltage signals; in response to the grid-side harmonics exceeding a threshold, generating a fault signal according to actual working conditions; switching the switching frequency of the four-quadrant from 450 Hz to 750 Hz through the TCU of each axis, and continuously performing BPF filtering calculation and harmonic component detection; in response to the recovery of the grid-side harmonics, when the detection signals of each axis are at a low level, switching the switching frequency of the four-quadrant from 750 Hz back to 550 Hz through the TCU of each axis.

[0021] The present invention enables the locomotive to automatically identify the low-order and high-order harmonics of the power grid. After the locomotive converter system receives fault signals such as the occurrence of grid-side harmonics, it actively adjusts the working frequency of the locomotive's four quadrants, so that the high-order harmonic components generated by the locomotive deviate from the frequency band (750-3750Hz) of the grid-side resonance, thereby reducing the locomotive Jp current, the primary and secondary current THD, improving the locomotive's operating efficiency, improving the efficiency of the main transformer, stabilizing the grid voltage, and avoiding locomotive damage caused by grid voltage fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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 description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A flow chart of a method for active control of grid-side harmonics provided by the present invention; Figure 2 A system module diagram for active control of grid-side harmonics provided by the present invention; Figure 3 A high and low order harmonic detection diagram of an embodiment of a method for active control of grid-side harmonics provided by the present invention; Figure 4 A control strategy diagram of an embodiment of a method for active control of grid-side harmonics provided by the present invention; Figure 5 A locomotive parameter waveform diagram in frequency conversion of an embodiment of a method for active control of grid-side harmonics provided by the present invention; Figure 6 An analysis diagram of grid-side harmonic contents at different frequencies of an embodiment of a method for active control of grid-side harmonics provided by the present invention; FIG7 is a comparison diagram of different four-quadrant switching frequencies and grid-side parameters according to an embodiment of a method for active control of grid-side harmonics provided by the present invention; Figure 8 A schematic diagram of the structure of an embodiment of a computer device provided by the present invention; Figure 9 A schematic diagram of the structure of an embodiment of a computer-readable storage medium provided by the present invention. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0025] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0026] The present invention proposes a method for active control of grid-side harmonics. Figure 1 ,include: S1, collecting the grid-side voltage signal and performing denoising processing, and performing BPF filtering calculation and harmonic component detection on the processed voltage signal to obtain the grid-side harmonics; S2, in response to the grid-side harmonic exceeding a threshold, generating a fault signal according to actual working conditions; S3, switch the switching frequency of the four quadrants from 450 Hz to 750 Hz through the TCU of each axis, and continue to perform BPF filtering calculation and harmonic component detection; S4. In response to the grid-side harmonic recovery, when the detection signals of each axis are all at a low level, the switching frequency of the four quadrants is switched back from 750 Hz to 550 Hz through the TCU of each axis.

[0027] By actively controlling the grid-side harmonics of electric locomotives, the impact of harmonics on the operation of electric locomotives can be effectively reduced. Harmonics may cause waveform distortion of current and voltage, increase the energy consumption of electric locomotives, and reduce operating efficiency. Actively controlling harmonics can ensure that electric locomotives operate under more stable and efficient conditions, thereby improving overall performance. When harmonic currents flow in the power grid, they may cause resonance of the grid, resulting in large fluctuations in grid voltage and current, and in severe cases may even damage grid equipment. At the same time, harmonics damage the power electronic devices inside the electric locomotive and shorten the service life of the equipment. By actively controlling harmonics, these risks can be effectively reduced and the normal operation of the power grid and electric locomotive equipment can be protected.

[0028] In some embodiments, see Figure 1 and Figure 3 The steps of filtering and calculating the processed voltage signal through BPF and detecting harmonic components include: Perform BPF calculations on the third harmonic frequency, the fifth harmonic frequency, and the sum of the harmonic frequencies of 750Hz-3750Hz respectively to obtain filtered signals within each frequency range; The amplitude of the filtered signal is calculated by the root mean square value, and the amplitude is extracted as the corresponding harmonic component.

[0029] BPF (Berkeley Packet Filter) can accurately identify the components of the third harmonic frequency in the power system through BPF calculation, which helps to detect potential harmonic problems in a timely manner. The third harmonic may cause a variety of problems in the power system, such as equipment overheating and increased power loss. Through BPF calculation, the impact of the third harmonic can be accurately evaluated and measures can be taken to reduce its interference with the system.

[0030] The fifth harmonic is also one of the common harmonics in the power system, which may have an adverse effect on equipment and systems. Through BPF calculation, the impact of the fifth harmonic on equipment and systems can be evaluated, and filters can be installed and equipment parameters adjusted to reduce the harm of the fifth harmonic. By reducing harmonic components such as the fifth harmonic, the power quality of the power system can be improved, ensuring the normal operation of equipment and the power consumption experience of users.

[0031] Harmonics in the frequency range of 750Hz-3750Hz may contain multiple components. Through BPF calculation, the overall characteristics of these harmonics can be comprehensively analyzed to provide comprehensive information for system optimization and governance. By calculating the sum of harmonic frequencies, the main harmonic sources can be identified. High-frequency harmonics pose a threat to the stability of the power system. Through BPF calculation, the stability of the system under the influence of high-frequency harmonics can be evaluated.

[0032] BPF technology has powerful data processing and analysis capabilities, which can significantly improve the diagnostic efficiency of harmonic problems and reduce the difficulty and cost of manual troubleshooting. By accurately analyzing the harmonic frequency characteristics, the configuration of equipment such as filters can be optimized, resource utilization efficiency can be improved, and operating costs can be reduced. By reducing the impact of harmonics on equipment and systems, the reliability of the power system can be enhanced and the safe and stable operation of the power grid can be guaranteed.

[0033] In some embodiments, see Figure 1 , Figure 3 4, the step of generating a fault signal in response to the grid-side harmonic exceeding a threshold value comprises: In response to detecting that the low-order harmonics or high-order harmonics exceed the threshold, the TCU of the detection shaft generates a fault signal and uploads the fault signal to the TCMS; TCMS receives the signal and outputs four-quadrant frequency switching instructions to the TCU of each axis.

[0034] The grid-side harmonics are detected according to the principle shown in Figure 3. When low-order harmonics or high-order harmonics are detected to exceed the threshold, the TCU of the detection axis uploads a fault signal to the TCMS. After receiving the signal, the TCMS outputs the four-quadrant frequency switching instruction to the TCUs of all axes. After receiving the signal, the TCUs of each axis uniformly switch the switching frequency of the four quadrants from 450Hz to 750Hz. When it is detected that the harmonic component has returned to the normal value, the TCMS confirms that the detection signals of all axes are at a low level (L), and then issues instructions to all TCUs. After receiving the signal, the TCUs of each axis uniformly switch the switching frequency of the four quadrants from 750Hz back to 550Hz. The specific control strategy is shown in Figure 4.

[0035] TCMS (Train Control and Management System), TCU (Transmission Control Unit).

[0036] Four-quadrant frequency switching means that the TCU can adjust the operating frequency in four different quadrants according to the instructions of the TCMS, thereby achieving precise control of the train's traction and braking force, helping the train to maintain the best operating state under different operating conditions and improving driving smoothness and passenger comfort.

[0037] During traction, by precisely controlling the operating frequency, the TCU can ensure that the motor operates in the most efficient manner, thereby reducing energy waste. During braking, four-quadrant frequency switching can more effectively recover braking energy, convert it into electrical energy and feed it back to the grid or use it for other auxiliary equipment, thereby achieving energy saving.

[0038] TCMS can quickly adjust the train's operating status by outputting four-quadrant frequency switching instructions to the TCU of each axle, helping the train to take prompt action to ensure driving safety when faced with emergencies or when emergency braking is required.

[0039] In some embodiments, see Figure 1 and Figure 3 , in response to detecting that a low-order harmonic or a high-order harmonic exceeds a threshold, the steps are: Compare the corresponding 3rd harmonic component and 5th harmonic component with the set threshold value; When the threshold is exceeded, the corresponding low-order harmonic components are output; Compare the sum of the 750Hz-3750Hz harmonic components with the set threshold; When the threshold is exceeded, the corresponding high-order harmonic components are output.

[0040] By detecting and responding to situations where harmonics exceed the threshold, measures can be taken to improve the voltage waveform and make it closer to a sine wave, thereby improving the quality of power and maintaining the stability of the power system and ensuring its normal operation.

[0041] In some embodiments, see Figure 1 and Figure 3 , the BPF filtering includes: For the third harmonic frequency, set a BPF with a center frequency of 150Hz; For the 5th harmonic frequency, set a BPF with a center frequency of 250Hz; For the harmonic frequencies of 750 Hz to 3750 Hz, a BPF with a bandwidth covering the frequency range is set.

[0042] By setting the BPF with a center frequency of 150Hz, the third harmonic frequency components in the power system can be accurately filtered out to prevent them from interfering with the normal operation of the power system. By setting the BPF with a center frequency of 250Hz, the pollution of the fifth harmonic to the power system can be effectively reduced. By setting the BPF with a bandwidth covering 750Hz~3750Hz, the harmonic components in this wide frequency band can be effectively filtered out, meeting the needs for high-frequency harmonic governance, comprehensively improving the reliability of the power system, and reducing the failure rate caused by harmonics. After filtering out harmonics, the energy efficiency of the power system can be improved, allowing equipment to operate in a more efficient manner and reducing energy waste.

[0043] In some embodiments, see Figure 1 The step of switching the switching frequency of the four quadrants from 450 Hz to 750 Hz through the TCU of each axis includes: Enter TCU; In the parameter setting of TCU, obtain the parameters related to the switching frequency of the four-quadrant rectifier and inverter, and modify the parameter value from 450Hz to 750Hz; The TCU operates at the modified switching frequency, and an oscilloscope is used to observe the current waveforms of the four-quadrant rectifier and inverter.

[0044] By modifying the switching frequency of the TCU, more precise control of the traction and braking process can be achieved. The current waveform observed by the oscilloscope can reflect the working status of the rectifier and inverter in real time.

[0045] Optimizing the switching frequency helps improve the conversion efficiency of the rectifier and inverter and reduce energy loss. The current waveform monitored by the oscilloscope shows the details of the energy conversion process, helping to identify potential efficiency bottlenecks and make improvements. Abnormal current waveforms observed by the oscilloscope are a precursor to system failure. Through real-time monitoring, potential problems can be discovered and handled in a timely manner to avoid the expansion of faults and improve the stability and reliability of the system. During the operation of the train, the load and operating conditions may change. The current waveform observed by the oscilloscope reflects these changes in real time, allowing the TCU to dynamically adjust the switching frequency to adapt to different loads and operating conditions and maintain stable operation of the system.

[0046] In some embodiments, see Figure 1 4, in response to the grid-side harmonic exceeding the threshold, generating a fault signal according to the actual working conditions also includes: When the actual working condition is parking and only the APU is working, the four-quadrant switching frequency controlled by the fault signal is 1100 Hz.

[0047] In the parking state, the system generates a fault signal with a four-quadrant switching frequency of 1100Hz, which serves as an obvious abnormal indication to help technicians quickly identify problems with the system. Since the fault signal is associated with a specific switching frequency, technicians can more easily locate the problem, such as a control logic error, sensor failure or other hardware problem.

[0048] The present invention proposes a system for active control of grid-side harmonics, see FIG2, comprising: The detection module 100 is configured to collect the grid-side voltage signal and perform denoising processing, and the processed voltage signal is filtered and calculated by BPF and harmonic component detection to obtain grid-side harmonics; A fault module 200 is configured to generate a fault signal according to actual working conditions in response to the grid-side harmonic exceeding a threshold; A switching module 300 is configured to switch the switching frequency of the four quadrants from 450 Hz to 750 Hz through the TCU of each axis, and continuously perform BPF filtering calculation and harmonic component detection; The recovery module 400 is configured to respond to the grid-side harmonic recovery, and when the detection signals of each axis are at a low level, the switching frequency of the four quadrants is switched from 750 Hz back to 550 Hz through the TCU of each axis.

[0049] The present invention can realize the locomotive to automatically identify the low-order and high-order harmonics of the power grid. After the locomotive converter system receives fault signals such as the occurrence of grid-side harmonics, it actively adjusts the working frequency of the locomotive's four quadrants, so that the high-order harmonic components generated by the locomotive deviate from the frequency band (750-3750Hz) of the grid-side resonance, thereby reducing the locomotive Jp current, the primary and secondary current THD, improving the locomotive's operating efficiency, improving the efficiency of the main transformer, stabilizing the grid voltage, and avoiding locomotive damage caused by grid voltage fluctuations.

[0050] In some embodiments, please refer to FIG. 5, FIG. 6 and Figure 7 Through actual tests in locomotive operation, the four quadrants were simulated by software to switch the frequency in normal switching action, and no faults occurred during the switching process. The figure below is the ground joint adjustment test result of alternating switching of the four quadrant switching frequency.

[0051] The four-quadrant switching frequency switching sequence is as follows: 450Hz→750Hz→1100Hz→450Hz As can be seen from the waveform in Figure 5, during the switching process of the four-quadrant switching frequency, the intermediate DC voltage and the primary voltage and current are very stable, and there is no effect on the motor current, etc. The control performance of the four-quadrant switching frequency switching is good.

[0052] It can be seen from Figure 6 that at 550Hz, 750Hz, and 1100Hz, the high-order harmonic components of the primary current have deviated from the grid-side resonant frequency band, avoiding grid voltage resonance in the locomotive. It can also be seen that after the four-quadrant frequency increase, the locomotive Jp current and primary current THD are significantly reduced. Figure 7 As shown. Moreover, the amplitude of the 38% high-order harmonic component current is not much different from that of 42% (very close). When the switching frequency is 750Hz, the JP current and high-order harmonic current amplitudes of 38% and 42% are very close. Therefore, the main transformer short-circuit impedance of 38% will not have a special impact on the large grid compared with 42%.

[0053] Through the promotion and application of the present invention on different electric locomotives, the reliability of locomotive operation can be effectively improved, and the mechanical damage of the whole vehicle caused by grid-side harmonics can be reduced. At the same time, the impact of high-order harmonics on the locomotive transmission system (converter, transformer, traction motor) is also reduced, and the maintenance cost of the whole vehicle throughout its life cycle is reduced.

[0054] Based on the same inventive concept, according to another aspect of the present invention, Figure 8As shown, an embodiment of the present invention further provides a computer device 30, which includes a processor 310 and a memory 320. The memory 320 stores a computer program 321 that can be run on the processor. When the processor 310 executes the program, the steps of the above method are performed.

[0055] Based on the same inventive concept, according to another aspect of the present invention, Figure 9 As shown, an embodiment of the present invention further provides a computer-readable storage medium 40, which stores a computer program 410 for executing the above method when executed by a processor.

[0056] The embodiment of the present invention may also include a corresponding computer device. The computer device includes a memory, at least one processor, and a computer program stored in the memory and executable on the processor, and the processor executes any one of the above methods when executing the program.

[0057] The memory, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules in the embodiments of the present application. The processor executes various functional applications and data processing of the device by running the non-volatile software programs, instructions and modules stored in the memory, that is, implementing the above method.

[0058] The memory may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the device, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In an embodiment, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the local module via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0059] Finally, it should be noted that a person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium of the program can be a disk, an optical disk, a read-only storage memory (ROM) or a random access memory (RAM), etc. The above-mentioned computer program embodiments can achieve the same or similar effects as the corresponding above-mentioned arbitrary method embodiments.

[0060] It will also be appreciated by those skilled in the art that various exemplary logic blocks, modules, circuits and algorithm steps described in conjunction with the disclosure herein can be implemented as electronic hardware, computer software or a combination of the two. In order to clearly illustrate this interchangeability of hardware and software, a general description has been given to the functions of various schematic components, blocks, modules, circuits and steps. Whether this function is implemented as software or hardware depends on specific applications and the design constraints imposed on the entire system. Those skilled in the art can implement the function in various ways for each specific application, but this implementation decision should not be interpreted as causing a departure from the disclosed scope of the embodiments of the present invention.

[0061] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope of the embodiments disclosed in the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. The serial numbers of the embodiments disclosed in the above embodiments of the present invention are for description only and do not represent the advantages and disadvantages of the embodiments. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0062] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0063] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for active control of grid-side harmonics, characterized in that: include: Collect the grid-side voltage signal and perform denoising processing, and perform BPF filtering calculation and harmonic component detection on the processed voltage signal to obtain grid-side harmonics; In response to the grid-side harmonic exceeding a threshold, generating a fault signal according to actual operating conditions; The switching frequency of the four quadrants is switched from 450Hz to 750Hz through the TCU of each axis, and BPF filtering calculation and harmonic component detection are continuously performed; In response to the grid-side harmonic recovery, when the detection signals of each axis are at a low level, the switching frequency of the four quadrants is switched back from 750 Hz to 550 Hz through the TCU of each axis.

2. The method for active control of grid-side harmonics according to claim 1, characterized in that: The steps of filtering and calculating the processed voltage signal through BPF and detecting harmonic components include: Perform BPF calculations on the third harmonic frequency, the fifth harmonic frequency, and the sum of the harmonic frequencies of 750Hz-3750Hz respectively to obtain filtered signals within each frequency range; The amplitude of the filtered signal is calculated by the root mean square value, and the amplitude is extracted as the corresponding harmonic component.

3. The method for active control of grid-side harmonics according to claim 2, characterized in that: The step of generating a fault signal in response to the grid-side harmonic exceeding a threshold comprises: In response to detecting that the low-order harmonics or high-order harmonics exceed the threshold, the TCU of the detection shaft generates a fault signal and uploads the fault signal to the TCMS; TCMS receives the signal and outputs four-quadrant frequency switching instructions to the TCU of each axis.

4. The method for active control of grid-side harmonics according to claim 3, characterized in that: The steps in response to detecting that a low-order harmonic or a high-order harmonic exceeds a threshold are: Compare the corresponding 3rd harmonic component and 5th harmonic component with the set threshold value; When the threshold is exceeded, the corresponding low-order harmonic components are output; Compare the sum of the 750Hz-3750Hz harmonic components with the set threshold; When the threshold is exceeded, the corresponding high-order harmonic components are output.

5. The method for active control of grid-side harmonics according to claim 1, characterized in that: The BPF filtering includes: For the third harmonic frequency, set a BPF with a center frequency of 150Hz; For the 5th harmonic frequency, set a BPF with a center frequency of 250Hz; For the harmonic frequencies of 750 Hz to 3750 Hz, a BPF with a bandwidth covering the frequency range is set.

6. The method for active control of grid-side harmonics according to claim 1, characterized in that: The step of switching the switching frequency of the four quadrants from 450 Hz to 750 Hz by the TCU of each axis includes: Enter TCU; In the parameter setting of TCU, obtain the parameters related to the switching frequency of the four-quadrant rectifier and inverter, and modify the parameter value from 450Hz to 750Hz; The TCU operates at the modified switching frequency, and an oscilloscope is used to observe the current waveforms of the four-quadrant rectifier and inverter.

7. The method for active control of grid-side harmonics according to claim 1, characterized in that: In response to the grid-side harmonic exceeding a threshold, generating a fault signal according to actual working conditions further includes: When the actual working condition is parking and only the APU is working, the four-quadrant switching frequency controlled by the fault signal is 1100 Hz.

8. A system for active control of grid-side harmonics, characterized in that: include: A detection module is configured to collect a grid-side voltage signal and perform denoising processing, and the processed voltage signal is filtered and calculated by BPF and harmonic component detection to obtain grid-side harmonics; a fault module configured to generate a fault signal in response to the grid-side harmonic exceeding a threshold value according to actual working conditions; A switching module is configured to switch the switching frequency of the four quadrants from 450 Hz to 750 Hz through the TCU of each axis, and continuously perform BPF filtering calculation and harmonic component detection; The recovery module is configured to respond to the grid-side harmonic recovery, and when the detection signals of each axis are at a low level, the switching frequency of the four quadrants is switched back to 550 Hz from 750 Hz through the TCU of each axis.

9. A computer device comprising: at least one processor; and a memory storing a computer program executable on the processor, wherein the processor executes the steps of a method for active control of grid-side harmonics as claimed in any one of claims 1 to 7 when executing the program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for active control of grid-side harmonics as claimed in any one of claims 1 to 7 are performed.

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