阅读说明：本技术 用于列车逆变器的三相输出电压电流畸变实时监测方法 (Three-phase output voltage and current distortion real-time monitoring method for train inverter ) 是由 马颖涛 杨二林 康晶辉 崔冬冬 董侃 杨宁 庞玉林 刘伟志 刘东辉 杜玉亮 程龙 于 2021-07-12 设计创作，主要内容包括：本发明提供一种用于列车逆变器的三相输出电压电流畸变实时监测方法,该方法包括：将逆变器输出的三相交流电信号转换为d轴电信号和q轴电信号；根据所述d轴电信号和所述q轴电信号得到畸变分量以及基波有效值；根据所述畸变分量以及所述基波有效值得到畸变因数,用于表征逆变器输出电压电流的谐波含量和三相对称性,可在逆变器工作过程中实时监测逆变器和负载的工作状态,计算较小、可以实时运算,便于集成到既有控制器中。(The invention provides a real-time monitoring method for three-phase output voltage and current distortion of a train inverter, which comprises the following steps: converting three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals; obtaining distortion components and fundamental wave effective values according to the d-axis electric signals and the q-axis electric signals; and obtaining a distortion factor according to the distortion component and the fundamental wave effective value, wherein the distortion factor is used for representing the harmonic content and three-phase symmetry of the output voltage and current of the inverter, the working states of the inverter and a load can be monitored in real time in the working process of the inverter, the calculation is small, the real-time operation can be performed, and the integration into the existing controller is facilitated.)

1. A real-time monitoring method for three-phase output voltage and current distortion of a train inverter is characterized by comprising the following steps:

converting three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals;

obtaining distortion components and fundamental wave effective values according to the d-axis electric signals and the q-axis electric signals;

and obtaining a distortion factor according to the distortion component and the fundamental effective value, and the distortion factor is used for representing the harmonic content and the three-phase symmetry of the output voltage and current of the inverter.

2. The method for monitoring the distortion of the three-phase output voltage and the current of the train inverter in real time according to claim 1, wherein the step of obtaining the distortion factor according to the distortion component and the fundamental effective value comprises the following steps:

dividing the distortion component by the fundamental effective value to obtain the distortion factor.

3. The method for monitoring the distortion of the three-phase output voltage and the current of the train inverter in real time according to claim 1, wherein the step of converting the three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals comprises the following steps:

and converting the three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals under a synchronous rotating coordinate system by adopting synchronous rotating coordinate conversion.

4. The method for real-time monitoring of three-phase output voltage and current distortion of train inverter as claimed in claim 3, wherein the transformation angle adopted in the transformation of synchronous rotation coordinate is a system angle ω for implementing voltage and current closed-loop control₀t, where ω₀To assist the inverter in outputting the fundamental angular frequency of the electrical signal.

5. The method for monitoring the distortion of the three-phase output voltage and the current of the train inverter in real time according to claim 1, wherein the obtaining of the distortion component and the fundamental effective value according to the d-axis electric signal and the q-axis electric signal comprises:

respectively extracting d-axis electric signal direct current components and q-axis electric signal direct current components corresponding to the d-axis electric signals and the q-axis electric signals;

subtracting the direct-current component of the d-axis electric signal from the d-axis electric signal to obtain a d-axis electric signal distortion component;

subtracting the direct-current component of the q-axis electric signal from the q-axis electric signal to obtain a q-axis electric signal distortion component;

obtaining an effective value of a fundamental wave by solving the direct current component of the d-axis electric signal and the direct current component of the q-axis electric signal;

and calculating the square sum, low-pass filtering and square root calculation of the d-axis electric signal distortion component and the q-axis electric signal distortion component to obtain the distortion component.

6. The method for monitoring the distortion of the three-phase output voltage and the current of the train inverter in real time according to claim 5, wherein the step of respectively extracting the d-axis electric signal direct current component and the q-axis electric signal direct current component corresponding to the d-axis electric signal and the q-axis electric signal comprises the following steps:

and performing low-pass filtering on the d-axis electric signal and the q-axis electric signal respectively to obtain a d-axis electric signal direct-current component and a q-axis electric signal direct-current component.

7. The real-time monitoring method for the distortion of the three-phase output voltage and the current of the train inverter as claimed in claim 6, wherein the low-pass filtering is first-order low-pass filtering or second-order low-pass filtering.

8. The utility model provides a three-phase output voltage current distortion real-time supervision device for train inverter which characterized in that includes:

the signal conversion module is used for converting the three-phase alternating current signal output by the inverter into a d-axis electric signal and a q-axis electric signal;

the distortion fundamental wave acquisition module is used for acquiring a distortion component and a fundamental wave effective value according to the d-axis electric signal and the q-axis electric signal;

and the distortion factor calculation module is used for obtaining a distortion factor according to the distortion component and the fundamental wave effective value and representing the harmonic content and the three-phase symmetry of the output voltage and current of the inverter.

9. An electronic device comprising a memory, a processor and a computer program stored on the memory and operable on the processor, wherein the processor when executing the program implements the steps of the method for real-time monitoring of three-phase output voltage current distortion for a train inverter of any one of claims 1 to 7.

10. A computer-readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method for real-time monitoring of three-phase output voltage current distortion for train inverters according to any one of claims 1 to 7.

Technical Field

The invention relates to the technical field of power electronics, in particular to a real-time monitoring method for three-phase output voltage and current distortion of a train inverter, which is suitable for detecting the output voltage and current distortion of vehicle-mounted inverters of motor train units and subway trains.

Background

The traction inverter and the auxiliary inverter are important vehicle-mounted equipment of the railway vehicle and respectively supply power to a traction motor and all other vehicle-mounted loads, including an air conditioner, an air compressor and the like.

The three-phase output current of the traction inverter and the three-phase output voltage and current of the auxiliary inverter can reflect the working state of the system, and indicate whether equipment faults exist or not, whether the load is unbalanced or not and the like. However, to calculate the harmonic distortion degree of the current, special equipment is usually required, and the method is not suitable for large-scale implementation in the operation process. Although the fast Fourier calculation is feasible in principle through the controller in the device, the fast Fourier calculation consumes more processor resources and takes long time, and the real-time control effect of the controller is influenced.

Disclosure of Invention

The invention provides a method, a device, electronic equipment and a computer-readable storage medium for monitoring three-phase output voltage and current distortion of a train inverter in real time, which can at least partially solve the problems in the prior art, can monitor the working states of the inverter and a load in real time in the working process of the inverter, has small calculation and can carry out real-time operation, and is convenient to integrate into the existing controller.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, a method for monitoring distortion of three-phase output voltage and current of a train inverter in real time is provided, which includes:

converting three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals;

obtaining distortion components and fundamental wave effective values according to the d-axis electric signals and the q-axis electric signals;

and obtaining a distortion factor according to the distortion component and the fundamental effective value, and the distortion factor is used for representing the harmonic content and the three-phase symmetry of the output voltage and current of the inverter.

Further, the deriving a distortion factor according to the distortion component and the fundamental effective value includes:

dividing the distortion component by the fundamental effective value to obtain the distortion factor.

Further, the converting the three-phase alternating current signal output by the inverter into a d-axis electric signal and a q-axis electric signal includes:

and converting the three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals under a synchronous rotating coordinate system by adopting synchronous rotating coordinate conversion.

Further, the transformation angle adopted during the transformation of the synchronous rotation coordinate is a system angle omega for implementing voltage and current closed-loop control₀t, where ω₀To assist the inverter in outputting the fundamental angular frequency of the electrical signal.

Further, obtaining a distortion component and a fundamental effective value from the d-axis electrical signal and the q-axis electrical signal includes:

respectively extracting d-axis electric signal direct current components and q-axis electric signal direct current components corresponding to the d-axis electric signals and the q-axis electric signals;

subtracting the direct-current component of the d-axis electric signal from the d-axis electric signal to obtain a d-axis electric signal distortion component;

subtracting the direct-current component of the q-axis electric signal from the q-axis electric signal to obtain a q-axis electric signal distortion component;

obtaining an effective value of a fundamental wave by solving the direct current component of the d-axis electric signal and the direct current component of the q-axis electric signal;

and calculating the square sum, low-pass filtering and square root calculation of the d-axis electric signal distortion component and the q-axis electric signal distortion component to obtain the distortion component.

Further, the extracting d-axis electric signal direct current components and q-axis electric signal direct current components corresponding to the d-axis electric signals and the q-axis electric signals respectively includes:

and performing low-pass filtering on the d-axis electric signal and the q-axis electric signal respectively to obtain a d-axis electric signal direct-current component and a q-axis electric signal direct-current component.

Further, the low-pass filtering is first-order low-pass filtering or second-order low-pass filtering.

In a second aspect, a real-time monitoring device for three-phase output voltage and current distortion of a train inverter is provided, which includes:

the signal conversion module is used for converting the three-phase alternating current signal output by the inverter into a d-axis electric signal and a q-axis electric signal;

the distortion fundamental wave acquisition module is used for acquiring a distortion component and a fundamental wave effective value according to the d-axis electric signal and the q-axis electric signal;

and the distortion factor calculation module is used for obtaining a distortion factor according to the distortion component and the fundamental wave effective value and representing the harmonic content and the three-phase symmetry of the output voltage and current of the inverter.

In a third aspect, an electronic device is provided, which includes a memory, a processor and a computer program stored in the memory and operable on the processor, and the processor implements the steps of the above-mentioned method for real-time monitoring distortion of three-phase output voltage and current of a train inverter when executing the program.

In a fourth aspect, a computer readable storage medium is provided, on which a computer program is stored, which computer program, when being executed by a processor, realizes the steps of the above-mentioned three-phase output voltage current distortion real-time monitoring method for a train inverter.

The invention provides a real-time monitoring method for three-phase output voltage and current distortion of a train inverter, which comprises the following steps: converting three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals; obtaining distortion components and fundamental wave effective values according to the d-axis electric signals and the q-axis electric signals; and obtaining a distortion factor according to the distortion component and the fundamental wave effective value, wherein the distortion factor is used for representing the harmonic content and three-phase symmetry of the output voltage and current of the inverter, the working states of the inverter and a load can be monitored in real time in the working process of the inverter, the calculation is small, the real-time operation can be performed, and the integration into the existing controller is facilitated.

In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. In the drawings:

FIG. 1 is a schematic circuit diagram of a train inverter in an embodiment of the present invention;

FIG. 2 is a schematic flow chart of a real-time monitoring method for three-phase output voltage and current distortion of a train inverter in an embodiment of the invention;

fig. 3 shows the specific steps of step S300 in an embodiment of the present invention;

FIG. 4 illustrates a schematic diagram of real-time monitoring of three-phase output voltage current distortion in an embodiment of the present invention;

fig. 5 is a block diagram of a real-time monitoring device for three-phase output voltage and current distortion in the embodiment of the invention;

FIG. 6 is a block diagram of another real-time monitoring apparatus for three-phase output voltage and current distortion in the embodiment of the present invention;

fig. 7 is a block diagram of an electronic device according to an embodiment of the invention.

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

It should be noted that the terms "comprises" and "comprising," and any variations thereof, in the description and claims of this application and the above-described drawings, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

In the train inverter monitoring technology in the prior art, special equipment is usually required to be adopted if the harmonic distortion degree of current is required to be calculated, and the train inverter monitoring technology is not suitable for large-scale implementation in the operation process. Although the fast Fourier calculation is feasible in principle through the controller in the device, the fast Fourier calculation consumes more processor resources and takes long time, and the real-time control effect of the controller is influenced.

In order to at least partially solve the technical problems in the prior art, the method for monitoring the distortion of the three-phase output voltage and the current of the train inverter in real time provided by the embodiment of the invention can monitor the working states of the inverter and a load in real time in the working process of the inverter, has small calculation and can carry out real-time operation, and is convenient to integrate into the existing controller.

FIG. 1 is a schematic circuit diagram of a train inverter in an embodiment of the present invention; as shown in fig. 1, a direct current input is sequentially passed through an inverter and a filter to obtain a corresponding alternating current output, current collection is performed at an output end of the inverter, voltage collection is performed at an output side of the filter, sampling of a three-phase output voltage or a three-phase output current of the inverter is realized, and the collected current and voltage are output to a controller, so that the controller performs real-time control of the inverter according to a certain control frequency based on the three-phase output voltage or the three-phase output current of the inverter, and the real-time monitoring method for the three-phase output voltage current distortion of the train inverter provided by the embodiment of the invention is executed.

FIG. 2 is a schematic flow chart of a real-time monitoring method for three-phase output voltage and current distortion of a train inverter in an embodiment of the invention; as shown in fig. 2, the real-time monitoring method for three-phase output voltage and current distortion of a train inverter may include the following steps:

step S100: converting three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals;

specifically, synchronous rotation coordinate transformation is adopted to convert three-phase alternating current signals output by the inverter into d-axis electric signals and q-axis electric signals in a synchronous rotation coordinate system, namely two-phase electric signals synchronously rotating at the frequency of the fundamental wave of the inverter.

Wherein, the transformation angle adopted in the transformation of the synchronous rotation coordinate is the system angle omega for implementing voltage and current closed-loop control₀t, where ω₀Outputting fundamental wave angular frequency (such as power frequency 2 pi x 50Hz) of electric signal for the auxiliary inverter, wherein the controller is responsible for inverting output of the inverter, and the control algorithm uses system coordinate transformation angle omega₀t。

It is worth to say that the synchronous rotation coordinate transformation herein is applied to the coordinate transformation angle ω₀the orientation method and the initial angle of t have no special requirements, only the three-phase alternating current quantity is converted into the direct current quantity under the synchronous rotating coordinate system, and the converted electric signal vector does not need to be oriented to the coordinate axis of the specific synchronous rotating coordinate system.

Step S200: obtaining distortion components and fundamental wave effective values according to the d-axis electric signals and the q-axis electric signals;

step S300: and obtaining a distortion factor according to the distortion component and the fundamental effective value, and the distortion factor is used for representing the harmonic content and the three-phase symmetry of the output voltage and current of the inverter.

Specifically, the distortion factor is obtained by dividing the distortion component by the fundamental effective value.

By adopting the technical scheme, although the calculated distortion factor is not the strictly defined total harmonic distortion rate, the harmonic distortion rate of the voltage or the current can be well approximated under the condition that three phases are basically symmetrical. When asymmetry occurs in the three phases, the distortion factor can very sensitively reflect the problem. Therefore, the distortion factor can well reflect abnormal conditions of the output voltage or current of the inverter.

The related calculation is simple algebraic operation, the operation amount is small, and the method is suitable for one iteration in each control period. Real-time calculation can be achieved.

In an alternative embodiment, referring to fig. 3, this step S200 may include the following:

step S210: respectively extracting d-axis electric signal direct current components and q-axis electric signal direct current components corresponding to the d-axis electric signals and the q-axis electric signals;

specifically, the d-axis electrical signals s are respectively aligned_dAnd said q-axis electrical signal s_qLow-pass filtering to obtain d-axis electric signal DC component s_dfQ-axis electric signal direct current component s_qfThis partial quantity corresponds to the symmetrical positive-sequence fundamental component.

The low-pass filtering is first-order low-pass filtering or second-order low-pass filtering, and the cutoff frequency ω c of the low-pass filtering is far lower than the fundamental frequency ω 0 of the electric signal output by the auxiliary inverter.

Step S220: subtracting the direct-current component of the d-axis electric signal from the d-axis electric signal to obtain a d-axis electric signal distortion component;

wherein d-axis electrical signal distortion component s_dr＝s_d-s_df。

Step S230: subtracting the direct-current component of the q-axis electric signal from the q-axis electric signal to obtain a q-axis electric signal distortion component;

wherein the q-axis electric signal distortion component s_qr＝s_q-s_qf。

Step S240: obtaining an effective value of a fundamental wave by solving the direct current component of the d-axis electric signal and the direct current component of the q-axis electric signal;

wherein the fundamental wave effective value s_d＝(s_df ²+s_qf ²)^1/2。

Step S250: and calculating the square sum, low-pass filtering and square root calculation of the d-axis electric signal distortion component and the q-axis electric signal distortion component to obtain the distortion component.

By adopting the technical scheme, the working states of the inverter and the load can be monitored in real time in the working process of the inverter, the calculation is small, the real-time operation can be realized, and the integration into the existing controller is convenient

In order to make those skilled in the art better understand the present application, a method for monitoring distortion of three-phase output voltage and current of a train inverter in real time according to an embodiment of the present invention is described in detail below with reference to fig. 4:

firstly, synchronous rotating coordinate conversion is adopted to convert a three-phase electric signal into a two-phase electric signal of a synchronous rotating coordinate system, and a system coordinate conversion angle omega is used in the conversion₀In the embodiment of the invention, the angle omega is converted to the system coordinate₀t has no special requirements on the orientation method and the initial angle. Converting three-phase electric signals into two-phase electric signals u synchronously rotating at the frequency of the fundamental wave of the inverter through coordinate conversion_d、u_q。

D-and q-axis electric signals u_d、u_qThe low-pass filtering may be first-order low-pass filtering or second-order low-pass filtering. Cut-off angular frequency omega of filter_cShould be much lower than the fundamental angular frequency omega₀In the present embodiment, the fundamental frequency is 2 × pi × 50Hz, and the cutoff angular frequency is 2 × pi × 5 Hz. After low-pass filtering, obtaining direct-current component d and q axis electric signals u_df、u_qf. This partial quantity pairA symmetrical positive sequence fundamental component should be applied.

By d, q-axis electric signals u after conversion_d、u_qSubtracting the symmetric positive sequence fundamental component u_df、u_qfAnd obtaining d and q axis electric signals of distortion components:

u_dr＝u_d-u_df(3)

u_qr＝u_q-u_qf(4)

for d and q axis electric signals u of direct current component_df、u_qfSolving an effective value to obtain a fundamental wave effective value:

u_f＝(u_df ²+u_qf ²)^1/2 (5)。

firstly, distortion components d and q axis electric signals u are processed_drAnd u_qrThe sum of squares is calculated and then passed through a first order low pass filter with a cut-off angular frequency of 2 x pi x 5Hz, resulting in an approximate average. Then, square root is calculated to obtain the distortion component u_r。

Then, the effective value u of the fundamental wave is judged_fWhether the value is less than or equal to a limit value A. If less than or equal to A, u is added_fThe value is assigned a. The value of A can be selected by referring to a rated value of the detected quantity, and an unreliable distortion factor is obtained in the starting process, the transient process or the shutdown state of the inverter. Finally, the distortion component u_rDivided by the fundamental effective value u_fThe distortion factor x% is obtained.

And finally, indicating the harmonic content and the three-phase symmetry of the electric signal output by the inverter through the distortion factor. When the three-phase electrical signal is symmetrical and has no harmonic components, the distortion factor x% is approximately equal to 0. When the distortion factor is larger than a certain limit value, harmonic distortion or three-phase asymmetry of three-phase electric signals is reflected. The limit value is set according to the specific application, for example, 10%, and it can be recognized whether the operating state of the inverter or its load is normal or not by using the method.

Based on the same inventive concept, the embodiment of the present application further provides a real-time monitoring device for three-phase output voltage and current distortion of a train inverter, which can be used to implement the method described in the foregoing embodiment, as described in the following embodiments. The principle of solving the problems of the three-phase output voltage and current distortion real-time monitoring device for the train inverter is similar to that of the method, so the implementation of the three-phase output voltage and current distortion real-time monitoring device for the train inverter can refer to the implementation of the method, and repeated parts are not repeated. As used hereinafter, the term "unit" or "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.

Fig. 5 is a block diagram of a three-phase output voltage and current distortion real-time monitoring device for a train inverter in an embodiment of the invention. As shown in fig. 5, the real-time monitoring device for three-phase output voltage and current distortion of the train inverter specifically includes: the device comprises a signal conversion module 10, a distortion fundamental wave acquisition module 20 and a distortion factor calculation module 30.

The signal conversion module 10 converts the three-phase alternating current signal output by the inverter into a d-axis electric signal and a q-axis electric signal;

the distortion fundamental wave obtaining module 20 obtains a distortion component and a fundamental wave effective value according to the d-axis electric signal and the q-axis electric signal;

the distortion factor calculation module 30 obtains a distortion factor according to the distortion component and the fundamental effective value, and is used for representing the harmonic content and the three-phase symmetry of the inverter output voltage and current.

By adopting the technical scheme, although the calculated distortion factor is not the strictly defined total harmonic distortion rate, the harmonic distortion rate of the voltage or the current can be well approximated under the condition that three phases are basically symmetrical. When asymmetry occurs in the three phases, the distortion factor can very sensitively reflect the problem. Therefore, the distortion factor can well reflect abnormal conditions of the output voltage or current of the inverter.

The related calculation is simple algebraic operation, the operation amount is small, and the method is suitable for one iteration in each control period. Real-time calculation can be achieved.

In another alternative embodiment, referring to fig. 6, it mainly comprises: the device comprises a coordinate transformation module, a direct current and alternating current extraction module, a fundamental wave effective value calculation module, a distortion amount calculation module and a distortion factor calculation module.

The coordinate conversion module adopts synchronous rotation coordinate conversion to convert three-phase alternating current signals output by the inverter and collected by the controller into d-axis and q-axis electric signals s under a synchronous rotation coordinate system_d、s_q.. The transformation angle used in the transformation can be a system angle omega which implements voltage and current closed-loop control in a controller₀t, where ω is₀The fundamental angular frequency of the electrical signal (e.g., power frequency 2 pi x 50Hz) is output for the auxiliary inverter. The synchronous rotating coordinate transformation has no specific requirement on the orientation angle, only the three-phase alternating current quantity is converted into the direct current quantity under the synchronous rotating coordinate system, and the converted electric signal vector does not need to be oriented to the coordinate axis of the specific synchronous rotating coordinate system.

The DC/AC extraction module extracts s_d、s_q.Into a direct current component and an alternating current component. Firstly, the converted d-axis and q-axis electric signals s are processed_d、s_qLow-pass filtering to obtain d-and q-axis electric signals s_df、s_qfThis partial quantity corresponds to the symmetrical positive-sequence fundamental component. The pair of converted d-axis and q-axis electric signals s_d、s_qLow-pass filtering with cut-off frequency omega_cShould be much lower than the fundamental frequency omega of the output electric signal of the auxiliary inverter₀。

By d, q-axis electrical signals s after conversion_d、s_qSubtracting the symmetric positive sequence fundamental component s_df、s_qfTo obtain d and q axis electrical signals s of distortion components_dr＝s_d-s_df、s_qr＝s_q-s_qf。

Fundamental wave effective value calculation module for direct current component d and q axis electric signals s_df、s_qfCalculating effective value to obtain fundamental effective value s_d＝(s_df ²+s_qf ²)^1/2。

The distortion quantity calculating module firstly carries out distortion component d and q axis electric signals s_drAnd s_qrCalculating the sum of squares, then passing through a low-pass filter, and then calculating the square root to obtain a distortion component s_r。

In the distortion factor calculation module, the distortion component s_rDivided by the fundamental effective value s_fAnd obtaining a distortion factor x%, wherein the harmonic content and the three-phase symmetry of the output voltage and current of the inverter can be indicated through the distortion factor.

The apparatuses, modules or units illustrated in the above embodiments may be implemented by a computer chip or an entity, or implemented by a product with certain functions. A typical implementation device is an electronic device, which may be, for example, a personal computer, a laptop computer, a cellular telephone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

In a typical example, the electronic device specifically includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the program to implement the steps of the above-mentioned real-time monitoring method for distortion of three-phase output voltage and current of the train inverter.

Referring now to FIG. 7, shown is a schematic diagram of an electronic device 600 suitable for use in implementing embodiments of the present application.

As shown in fig. 7, the electronic apparatus 600 includes a Central Processing Unit (CPU)601 that can perform various appropriate works and processes according to a program stored in a Read Only Memory (ROM)602 or a program loaded from a storage section 608 into a Random Access Memory (RAM)) 603. In the RAM603, various programs and data necessary for the operation of the system 600 are also stored. The CPU601, ROM602, and RAM603 are connected to each other via a bus 604. An input/output (I/O) interface 605 is also connected to bus 604.

The following components are connected to the I/O interface 605: an input portion 606 including a keyboard, a mouse, and the like; an output portion 607 including a display such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, and a speaker; a storage section 608 including a hard disk and the like; and a communication section 609 including a network interface card such as a LAN card, a modem, or the like. The communication section 609 performs communication processing via a network such as the internet. The driver 610 is also connected to the I/O interface 606 as needed. A removable medium 611 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 610 as necessary, so that a computer program read out therefrom is mounted as necessary on the storage section 608.

In particular, according to an embodiment of the present invention, the processes described above with reference to the flowcharts may be implemented as computer software programs. For example, an embodiment of the present invention includes a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the above-described method for real-time monitoring of three-phase output voltage current distortion for a train inverter.

In such an embodiment, the computer program may be downloaded and installed from a network through the communication section 609, and/or installed from the removable medium 611.

Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules 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, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.

For convenience of description, the above devices are described as being divided into various units by function, and are described separately. Of course, the functionality of the units may be implemented in one or more software and/or hardware when implementing the present application.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.