CN112345839A - Online identification method, device and circuit for secondary side leakage reactance of transformer - Google Patents
Online identification method, device and circuit for secondary side leakage reactance of transformer Download PDFInfo
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Abstract
The invention provides an online identification method, device and circuit for secondary side leakage reactance of a transformer. The method specifically comprises the steps of obtaining secondary side alternating voltage of the transformer; acquiring input voltage and input current of the front end of the converter; calculating a grid-side flux linkage and an alternating-current-side flux linkage based on the secondary-side alternating-current voltage and the input voltage respectively; and calculating the front-end inductance of the converter based on the grid-side flux linkage, the alternating-current-side flux linkage and the input current to represent the secondary side leakage reactance of the transformer. The invention also provides a device and a circuit for realizing the online identification method. According to the transformer secondary side leakage reactance online identification method, device and circuit, the leakage reactance value can be accurately identified, the precision is high, and engineering implementation is facilitated.
Description
Technical Field
The invention relates to the field of control of power electronic converters, in particular to online identification of secondary side leakage reactance of a transformer at the front end of a converter.
Background
The converter, also known as rectifier, net side converter, its one end links to each other with alternating current electric wire netting, and the other end links to each other with direct current return circuit, can realize the two-way flow of energy, all has very extensive application in fields such as some high-power traction transmission, direct current transmission, new forms of energy. Particularly for electrified railways, the performance of the high-power traction converter directly influences the running performance of the locomotive as the heart of a high-power locomotive and a motor train unit serving as core equipment of the electrified railways.
The performance of the high-power traction converter is closely related to a traction transformer at the front end of the converter besides the self design and control strategy. In the control application of the grid-side converter, the front-end inductance parameter of the converter is an important parameter. Because the secondary winding of the traction transformer is connected with the traction converter, the secondary leakage reactance of the transformer is often used as the inductance of the front end of the converter, and therefore, the accuracy of the secondary leakage reactance parameter of the transformer directly influences the control precision, the response speed and the harmonic performance.
Generally speaking, the leakage reactance of the transformer used in the control is data provided by a transformer design file, and the leakage reactance value may have a certain difference from a nominal value due to the difference formed by the manufacturing process and the inductance carried by a connecting cable or a busbar in the practical application of the device, and the deviation may affect the accurate control of the grid-side converter, cause the inaccuracy of the four-quadrant control of the converter, and further affect the harmonic performance of the locomotive. If the error is too large, a system can have large reactive component, sometimes the system can be unstable, the alternating current or direct current voltage is abnormal, and in serious cases the system can be out of control, so that the protection action or the damage of a converter can be caused.
Therefore, an effective method for identifying the leakage reactance of the traction transformer on line is needed, which can accurately identify the inductance parameter required by controlling the grid-side converter through a certain control algorithm without additionally adding any other equipment, thereby providing support for the precise control and optimization of the converter and having universality.
Disclosure of Invention
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
As described above, in order to solve the problem that the secondary side leakage reactance of the transformer at the front end of the converter cannot be accurately identified online in the prior art, the present invention provides an online identification method for the secondary side leakage reactance of the transformer, where the secondary side winding of the transformer is connected to the converter, and the online identification method specifically includes:
acquiring secondary side alternating voltage of the transformer;
acquiring input voltage and input current of the front end of the converter;
calculating a grid-side flux linkage and an alternating-current-side flux linkage based on the secondary-side alternating-current voltage and the input voltage respectively; and
and calculating the front-end inductance of the converter based on the grid-side flux linkage, the alternating-current-side flux linkage and the input current so as to represent the secondary side leakage reactance of the transformer.
In an embodiment of the above online identification method, optionally, the step of calculating the front-end inductance further includes:
calculating a flux linkage difference value between the grid side flux linkage and the alternating current side flux linkage; and
and calculating the ratio of the flux linkage difference value to the input current as the front-end inductance.
In an embodiment of the above online identification method, optionally, the step of calculating the front-end inductance further includes:
converting the flux linkage difference into flux linkage difference direct current quantity; and
converting the input current into an input current direct current quantity; wherein
The step of calculating the above ratio further comprises:
and calculating the ratio of the direct current quantity of the flux linkage difference value to the direct current quantity of the input current to be the front-end inductance.
In an embodiment of the above online identification method, optionally, the step of calculating the front-end inductance further includes:
low-pass filtering the flux linkage difference direct current quantity and the input current direct current quantity respectively; wherein
The step of calculating the above ratio further comprises:
and calculating the ratio of the flux linkage difference direct current quantity after the low-pass filtering treatment to the input current direct current quantity to be the front-end inductor.
In an embodiment of the above online identification method, optionally, the step of obtaining the input voltage further includes:
acquiring a switching function of the converter and a direct-current voltage at the rear end of the converter; and
and calculating the product of the switching function and the direct current voltage as the input voltage.
In an embodiment of the online identification method, optionally, the secondary ac voltage and the input voltage are integrated to obtain the grid-side flux linkage and the ac-side flux linkage, respectively.
In an embodiment of the above online identification method, optionally, the integration operation is an anti-bias integration operation.
The invention also provides an online identification device for secondary side leakage reactance of a transformer, wherein a secondary side winding of the transformer is connected with a current transformer, the online identification device specifically comprises a memory and a processor, and the processor is configured to:
acquiring secondary side alternating voltage of the transformer;
acquiring input voltage and input current of the front end of the converter;
calculating a grid-side flux linkage and an alternating-current-side flux linkage based on the secondary-side alternating-current voltage and the input voltage respectively; and
and calculating the front-end inductance of the converter based on the grid-side flux linkage, the alternating-current-side flux linkage and the input current so as to represent the secondary side leakage reactance of the transformer.
In an embodiment of the above online identification device, optionally, the step of calculating the front-end inductance by the processor further includes:
calculating a flux linkage difference value between the grid side flux linkage and the alternating current side flux linkage; and
and calculating the ratio of the flux linkage difference value to the input current as the front-end inductance.
In an embodiment of the above online identification device, optionally, the step of calculating the front-end inductance by the processor further includes:
converting the flux linkage difference into flux linkage difference direct current quantity; and
converting the input current into an input current direct current quantity; wherein
The step of calculating the ratio by the processor further comprises:
and calculating the ratio of the direct current quantity of the flux linkage difference value to the direct current quantity of the input current to be the front-end inductance.
In an embodiment of the above online identification device, optionally, the step of calculating the front-end inductance by the processor further includes:
low-pass filtering the flux linkage difference direct current quantity and the input current direct current quantity respectively; wherein
The step of calculating the ratio by the processor further comprises:
and calculating the ratio of the flux linkage difference direct current quantity after the low-pass filtering treatment to the input current direct current quantity to be the front-end inductor.
In an embodiment of the online identification device, optionally, the step of the processor obtaining the input voltage further includes:
acquiring a switching function of the converter and a direct-current voltage at the rear end of the converter; and
and calculating the product of the switching function and the direct current voltage as the input voltage.
In an embodiment of the online identification device, optionally, the processor performs an integration operation on the secondary ac voltage and the input voltage to obtain the grid-side flux linkage and the ac-side flux linkage, respectively.
In an embodiment of the above online identification device, optionally, the integration operation is an anti-bias integration operation.
The invention also provides an online identification circuit for secondary side leakage reactance of a transformer, wherein a secondary side winding of the transformer is connected with a current transformer, and the online identification circuit comprises:
a first voltage sensor for acquiring a secondary side alternating voltage of the transformer;
the second voltage sensor is used for acquiring the input voltage of the front end of the converter;
the current sensor is used for acquiring the input current of the front end of the converter;
an integrating circuit for simulating a grid-side flux linkage and an ac-side flux linkage based on the secondary ac voltage and the input voltage; and
and a division circuit for simulating a secondary leakage reactance of the transformer based on the grid-side flux linkage, the alternating-current-side flux linkage, and the input current.
In an embodiment of the above-mentioned online identification circuit, optionally, the online identification circuit further includes:
a subtraction circuit for calculating a flux linkage difference between the grid-side flux linkage and the ac-side flux linkage; wherein
The divider circuit simulates the secondary leakage reactance based on calculating the flux linkage difference and the input current.
In an embodiment of the above-mentioned online identification circuit, optionally, the online identification circuit further includes: the first low-pass filter and the amplifier are used for converting the flux linkage difference into flux linkage difference direct current quantity; converting the input current into an input current direct current quantity; wherein
The division circuit simulates the secondary leakage reactance based on calculating the flux linkage difference DC quantity and the input current DC quantity.
In an embodiment of the above-mentioned online identification circuit, optionally, the online identification circuit further includes: a second low-pass filter for low-pass filtering the flux linkage difference dc component and the input current dc component; wherein
The division circuit simulates the secondary side leakage reactance based on the flux linkage difference direct current quantity and the input current direct current quantity after low-pass filtering processing.
The present invention also provides a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the steps of the online identification method according to any of the above embodiments.
According to the online identification method, the online identification device and the online identification circuit for the transformer secondary side leakage reactance provided by the invention, the operation of current and voltage is skillfully converted into the operation of flux linkage, so that the inductance of the front end of the grid-side converter can be simply and reliably estimated, the secondary side leakage reactance of the transformer is represented, and the possibility is provided for the accurate control and optimization of the converter. The method and the device do not need to additionally add any other equipment, can be generally applied to the application field needing converter control, and have compatibility.
Drawings
The above features and advantages of the present disclosure will be better understood upon reading the detailed description of embodiments of the disclosure in conjunction with the following drawings. In the drawings, components are not necessarily drawn to scale, and components having similar associated characteristics or features may have the same or similar reference numerals.
Fig. 1 shows a topology diagram of a transformer and a grid-side converter;
FIG. 2 is a flow chart of the online identification method provided by the present invention.
FIG. 3 is a flow chart of a preferred embodiment of the online identification method provided by the present invention.
Fig. 4 shows a schematic diagram of an online identification device provided by the present invention.
FIG. 5 is a schematic diagram of a preferred embodiment of the online identification circuit provided by the present invention.
Reference numerals
100 transformer
110 primary winding
120-time side winding
200 current transformer
300 on-line identification device
301 processor
302 memory
410 first voltage sensor
412 second voltage sensor
414 Current sensor
420 integrating circuit
430 subtraction circuit
440 AC-to-DC circuit
442 first low pass filter
444 amplifier
450 second low pass filter
460 division circuit
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. It is noted that the aspects described below in connection with the figures and the specific embodiments are only exemplary and should not be construed as imposing any limitation on the scope of the present invention.
As described above, the present invention provides an effective method for identifying leakage reactance of a traction transformer on-line, which can accurately identify inductance parameters required by controlling a grid-side converter through a certain control algorithm without adding any additional equipment, thereby providing support for accurate control and optimization of the converter, and having universality.
Referring to fig. 1, fig. 1 is a topology diagram illustrating a connection relationship between a transformer and a grid-side converter. It will be understood by those skilled in the art that the structure diagram shown in fig. 1 is only schematic and not limiting to the actual connection relationship between the grid-side converter and the transformer.
As shown in fig. 1, the left side of the dotted line is a transformer 100, wherein the transformer 100 further comprises a primary winding 110 and a plurality of secondary windings 120, and it is understood that the primary winding 110 can be considered to be connected to the input end of the transformer 100, and the secondary windings 120 can be considered to be connected to the output end of the transformer 100, so as to output voltage to a load.
In the schematic diagram shown in fig. 1, the current transformer 200, i.e. the load connected to the secondary winding 120, is to the right of the dashed line. The converter 200 is an alternating current-direct current (AC-DC) rectifier, and is configured to convert an AC power at a grid side into a DC power and output the DC power. Further, the current transformer 200 applicable to the online identification method provided by the present invention is not limited to single-phase or three-phase, and the current transformer 200 may be a single-phase current transformer or a three-phase current transformer, which has universality.
In the structure shown in FIG. 1, U0For the secondary ac voltage of the traction transformer 100, it is understood that the secondary ac voltage is not limited to single-phase or three-phase, and may be single-phase ac or three-phase ac. R and L are the equivalent resistance and the equivalent inductance, U, between the supply network and the network-side AC/DC converter 200, respectivelyabIs the AC input voltage, C, of the grid-side AC/DC converter 200dTo support the capacitance, i is the input current of the grid-side AC/DC converter 200.
In the schematic diagram of the structure shown in fig. 1, the following fixed relational expressions exist for the circuit parameters:
since in practice the resistance R on the connecting cable between the traction transformer secondary winding 120 and the converter 200 is much smaller than the inductance L, i.e.: r L, so to simplify the calculation, the effect of the resistance R can be neglected, resulting in:
in the above formula, since the integral of the voltage with respect to time can be regarded as the magnetic flux, and can be characterized by a virtual flux linkage, the following formula can be obtained:
in the above formula, #0Representing the virtual flux linkage component, ψ, of the power networkabRepresents the virtual flux linkage component of the ac side voltage of the grid side converter and further, it can be seen that the virtual flux linkage psi is based on the grid voltage0Virtual flux linkage psi of AC side voltage with converterabCan be obtained byObtaining a virtual flux linkage equivalent to the secondary leakage reactance of the traction transformer, and obtaining the following formula after transforming the formula:
that is, the virtual flux linkage ψ can be passed through the grid voltage0Virtual flux linkage psi of AC side voltage with converterabThe ratio of the difference value to the current value of (a) represents the equivalent inductance value of the secondary winding of the traction transformer, namely:
therefore, referring to fig. 2 together, fig. 2 shows a flowchart of the online identification method provided by the present invention. In order to accurately monitor a virtual flux linkage equivalent to the leakage reactance of the secondary side of the transformer, the online identification method provided by the invention comprises the following steps:
step S1: acquiring secondary side alternating voltage of the transformer;
step S2: acquiring input voltage and input current of the front end of the converter;
step S3: calculating a power grid side magnetic linkage and an alternating current side magnetic linkage based on the secondary side alternating voltage and the input voltage; and
step S4: and calculating the front-end inductance of the converter based on the power grid side magnetic linkage, the alternating current side magnetic linkage and the input current to represent the secondary side leakage reactance of the transformer.
Specifically, in step S1, it is necessary to obtain the secondary side ac voltage U of the transformer 1000。
In step S2, it is necessary to obtain the AC input voltage U of the grid-side AC/DC converter 200abAnd the input current i of the grid-side AC/DC converter 200.
In the above step S3, the secondary side ac voltage U is passed0Method for obtaining power grid side magnetic linkage psi by integrating time0， ψ0＝∫U0dt; by means of an AC input voltage UabIntegration over time to obtain the AC side flux linkage psiab， ψab＝∫Uabdt。
In the above step S4, the grid-side flux linkage ψ is calculated0And AC side flux linkage psiabAnd calculating the ratio of the flux linkage difference to the input current i to obtain the front-end inductance of the converter to represent the secondary side leakage reactance of the transformer.
Furthermore, in the above embodiment, the AC input voltage UabCan be directly acquired by additionally adding a voltage sensor. In another embodiment, the ac input voltage U is preferably obtained by generating a switching function and monitoring the back-end dc voltage when the network-side converter 200 is operating normally, since the basic function of the network-side converter is to maintain the ac-side unity power factor and stabilize the dc voltage, and the switching function and the dc voltage are obtained automatically when the network-side converter 200 is operating normallyabCan be characterized by the product of the switching function and the dc voltage, see the following equation:
Uab＝f(S1,S2,S3,…)*Ud；
wherein S is1,S2,S3The state of each switching tube in the grid-side converter, f (S)1,S2,S3…) represents a function of the formation of the tube states of these switches, UdThe direct current voltage is output by the rear end of the grid-side converter. By switching function f (S)1,S2,S3…) and a direct voltage UdThe product obtained can obtain equivalent AC input voltage U without adding additional voltage sensorabTherefore, the online identification method provided by the invention has less requirements on hardware structures and is more universal.
Further, preferably, in the above-described embodiment, the alternating voltage U is passed through the secondary side0Method for obtaining power grid side magnetic linkage psi by integrating time0And by an alternating input voltage UabIntegration over time to obtain AC side magnetic linkage psiabStep (2) ofIn order to avoid the problems of integral saturation and initial value caused by pure integration, an anti-bias integral algorithm can be used to replace a pure integration link so as to achieve the purpose of eliminating direct current bias in a steady state. Specifically, those skilled in the art can select suitable parameters to perform the above-mentioned integration algorithm for resisting bias according to actual needs, and the method is not limited herein. It should be noted that the above-mentioned integration algorithm for resisting bias is an integration algorithm for achieving the purpose of eliminating dc bias when reaching steady state, and is a preferred integration algorithm, and is not a limitation of the integration algorithm of the present application. Those skilled in the art can also achieve the same steady-state dc offset cancellation based on other integration algorithms.
Further, in the step of calculating the ratio of the flux linkage difference to the input current i, the virtual flux linkage ψ is calculated due to the grid voltage0Virtual flux linkage psi of AC side voltage with converterabThe input current i of the network side converter is also the power frequency alternating current, and if the input current i is directly divided by the power frequency alternating current and the power frequency alternating current, the input current i can cause great burrs to appear when i is 0, so that great inaccuracy is brought to the estimation of the inductance. Therefore, in an embodiment, preferably, the step of calculating the ratio of the flux linkage difference to the input current i further includes dividing the grid voltage by the virtual flux linkage ψ0Converting into DC, and converting the AC side voltage of the converter into virtual flux psiabAnd converting the input current i into direct current, so that the inductance of the front end of the grid-side converter can be accurately estimated.
In the above embodiment, in order to avoid the division operation of the ac flow rate during the inductance estimation, the dc flow rate may be obtained by extracting the amplitude of the ac flow rate. Further, the step of extracting the ac traffic amplitude may be implemented by Fast Fourier transform (FFT, which is a Fast algorithm of Discrete Fourier Transform (DFT), and is obtained by improving the algorithm of the DFT according to characteristics of odd, even, imaginary, and real of the DFT). It should be understood by those skilled in the art that the above-mentioned conversion of ac flow into dc flow can be achieved by existing or future means, and the above-mentioned examples are only illustrative and not intended to limit the present invention.
Therefore, after the step of converting the ac value into the dc value, the inductance to be obtained can be characterized by the following formula:
therefore, by the method, the inductance parameter of the front end of the converter can be effectively and accurately estimated, and the secondary side leakage reactance parameter of the front-end transformer can be represented.
Preferably, in another embodiment, the online identification method provided by the present invention further includes additionally performing a low-pass filtering process on the obtained flux linkage dc amount and the current dc amount. Because the leakage reactance parameter of the transformer to be monitored is a stable steady-state value and is not mixed with high-frequency components, the high-frequency interference in the signal is filtered by the low-pass filter, so that the stable low-frequency component can be obtained, namely the required leakage reactance value of the transformer can be obtained.
Therefore, referring to fig. 3, fig. 3 shows a flow chart of the online identification method provided by the present invention in combination with all the above preferred embodiments. As shown in fig. 3, in step S110, by obtaining the secondary ac voltage, the switching function and the dc voltage, the front-end ac input voltage of the converter can be obtained without additionally providing a voltage sensor, which effectively reduces the hardware requirement of the method. In step S200, by performing anti-bias integration on the ac input voltage represented by the product of the secondary ac voltage, the switching function, and the dc voltage, a simulated flux linkage can be obtained, and the purpose of eliminating the dc bias in a steady state can be achieved. In step S310, the virtual flux linkage component ψ is given to the above-described power grid0And the virtual flux linkage component psi of the AC side voltage of the grid side converterabThe operation of converting the alternating current quantity into the direct current quantity is carried out, and preparation is made for subsequent more accurate calculation. Also in step S320, for the current transformer acquired in step S120The input current is converted from alternating current to direct current, so that preparation is provided for subsequent more accurate calculation. In step S410 and step S420, low-pass filtering processing is performed on the obtained flux linkage difference dc quantity and the input current dc quantity, so that high-frequency interference in the signal can be filtered out, a relatively stable low-frequency component is obtained, and the calculation requirement is met. Finally, in step S500, the dc link difference value after the low-pass filtering process can be divided by the dc input current to calculate the front-end inductance L of the converter, and the secondary leakage reactance of the front-end transformer can be represented.
According to the online identification method provided by the invention, the inductance parameter required by controlling the network side converter can be accurately identified through a certain control algorithm and a virtual flux linkage under the condition that no other equipment is additionally arranged, and the secondary side leakage reactance of the front-end transformer can be represented. When the front-end transformer has a significant problem, the leakage reactance value of the front-end transformer can be changed, and the transformer fault can be accurately diagnosed by identifying the leakage reactance of the front-end transformer through the online identification method of the secondary side leakage reactance of the front-end transformer. Or when the leakage reactance value of the front-end transformer changes, the accurately identified leakage reactance value can be brought into control to improve the control effect of the grid-side converter, so that support is provided for accurate control and optimization of the converter. The online identification method provided by the invention can be generally applied to the application field needing converter control, and has compatibility.
The invention also provides an online identification device for the secondary side leakage reactance of the transformer, please refer to fig. 4, and fig. 4 shows a schematic diagram of the online identification device. As shown in FIG. 4, the online identification device 300 includes a processor 301 and a memory 302. The processor 301 of the online identification apparatus 300 can implement the online identification method described above when executing the computer program stored in the memory 302, for which reference is specifically made to the description of the online identification method, which is not repeated herein.
Fig. 5 is a schematic diagram of an online identification circuit for secondary side leakage reactance of a transformer, and fig. 5 is a schematic diagram of a preferred embodiment of the online identification circuit provided in the present invention. The online identification circuit provided by the invention comprises a first voltage sensor 410 for obtaining the secondary side alternating voltage in step S100; a second voltage sensor 412 for obtaining the front ac input voltage of the converter; a current sensor 414 for obtaining an analog signal of the input current in step S210; the integrating circuit 420 is used for integrating the secondary side alternating voltage and the alternating input voltage to obtain a simulated grid side magnetic flux linkage and a simulated alternating side magnetic flux linkage; the subtraction circuit 430 is configured to perform subtraction on the grid-side flux linkage and the ac-side flux linkage obtained after passing through the integration circuit 420 to obtain a flux linkage difference value; an ac-dc circuit 440 including a first low pass filter 442 and an amplifier 444, for performing an ac-dc amount operation on the flux linkage difference obtained by the subtraction circuit 430, and performing an ac-dc amount operation on the input current obtained by the current sensor 414; a second low-pass filter 450 for further performing low-pass filtering on the flux linkage difference dc amount and the input current dc amount obtained after passing through the transpose circuit 440; and a division circuit 460, which divides the flux linkage difference dc quantity obtained by the second low-pass filter 450 and the input current dc quantity to obtain a voltage value that can be used to represent the front-end inductance, collects the voltage value, and can also represent the secondary leakage reactance value according to the voltage value.
Those skilled in the art will appreciate that the integrating circuit, the subtracting circuit, the dividing circuit, the low-pass filter, the amplifier, and the like included in the online identification circuit described above can be implemented by building an analog circuit. In addition, various operations of integration, subtraction and division in the integration, subtraction and division circuits can be realized through the existing or different specific circuit structures, signal amplification in the amplifier is realized, and signal conversion, extraction and interference resistance of the low-pass filter are realized.
According to the online identification circuit provided by the invention, the online identification method provided by the invention can be realized through the analog circuit, and the secondary side leakage reactance of the front-end transformer can be simply and efficiently simulated. When the front-end transformer has a significant problem, the leakage reactance value of the front-end transformer can be changed, and the transformer fault can be accurately diagnosed by identifying the leakage reactance of the front-end transformer through the online identification method of the secondary side leakage reactance of the front-end transformer. Or when the leakage reactance value of the front-end transformer changes, the accurately identified leakage reactance value can be brought into control to improve the control effect of the grid-side converter, so that support is provided for accurate control and optimization of the converter. The online identification method provided by the invention can be generally applied to the application field needing converter control, and has compatibility.
The online identification method, device and circuit provided by the invention have been described so far. The present invention also provides a computer storage medium having a computer program stored thereon, which when executed by a processor implements the steps of the above-described online identification method.
Those of skill in the art would understand that information, signals, and data may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits (bits), symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted" and "coupled" are to be construed broadly, e.g., as meaning fixedly attached, detachably attached, or integrally attached; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those of ordinary skill in the art.
The various illustrative logical modules and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.
In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disks) usually reproduce data magnetically, while discs (discs) reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (19)
1. An on-line identification method for secondary side leakage reactance of a transformer, wherein a secondary side winding of the transformer is connected with a current transformer,
acquiring secondary side alternating voltage of the transformer;
acquiring input voltage and input current of the front end of the converter;
calculating a grid side flux linkage and an alternating side flux linkage based on the secondary side alternating voltage and the input voltage respectively; and
and calculating the front-end inductance of the converter based on the power grid side magnetic linkage, the alternating current side magnetic linkage and the input current so as to represent the secondary side leakage reactance of the transformer.
2. The on-line identification method of claim 1, wherein the step of calculating the front-end inductance further comprises:
calculating a flux linkage difference value of the power grid side flux linkage and the alternating current side flux linkage; and
and calculating the ratio of the flux linkage difference value to the input current as the front-end inductance.
3. The on-line identification method of claim 2, wherein the step of calculating the front-end inductance further comprises:
converting the flux linkage difference into flux linkage difference direct current quantity; and
converting the input current into an input current direct current quantity; wherein
The step of calculating the ratio further comprises:
and calculating the ratio of the direct current quantity of the flux linkage difference value to the direct current quantity of the input current as the front-end inductance.
4. The on-line identification method of claim 3, wherein the step of calculating the front-end inductance further comprises:
respectively low-pass filtering the flux linkage difference direct current quantity and the input current direct current quantity; wherein
The step of calculating the ratio further comprises:
and calculating the ratio of the flux linkage difference direct current quantity after the low-pass filtering treatment to the input current direct current quantity to be the front-end inductor.
5. The online identification method of claim 1, wherein the step of obtaining the input voltage further comprises:
acquiring a switching function of the converter and a direct-current voltage at the rear end of the converter; and
and calculating the product of the switching function and the direct current voltage as the input voltage.
6. The online identification method according to claim 1, wherein the secondary ac voltage and the input voltage are integrated to obtain the grid-side flux linkage and the ac-side flux linkage, respectively.
7. The on-line identification method of claim 6, wherein the integration operation is an anti-bias integration operation.
8. An online identification device for secondary side leakage reactance of a transformer, wherein the secondary side winding of the transformer is connected with a current transformer, the online identification device comprises a memory and a processor, and the processor is configured to:
acquiring secondary side alternating voltage of the transformer;
acquiring input voltage and input current of the front end of the converter;
calculating a grid side flux linkage and an alternating side flux linkage based on the secondary side alternating voltage and the input voltage respectively; and
and calculating the front-end inductance of the converter based on the power grid side magnetic linkage, the alternating current side magnetic linkage and the input current so as to represent the secondary side leakage reactance of the transformer.
9. The on-line identification device of claim 8 wherein the step of the processor calculating the front-end inductance further comprises:
calculating a flux linkage difference value of the power grid side flux linkage and the alternating current side flux linkage; and
and calculating the ratio of the flux linkage difference value to the input current as the front-end inductance.
10. The on-line identification method of claim 9, wherein the step of the processor calculating the front-end inductance further comprises:
converting the flux linkage difference into flux linkage difference direct current quantity; and
converting the input current into an input current direct current quantity; wherein
The step of the processor calculating the ratio further comprises:
and calculating the ratio of the direct current quantity of the flux linkage difference value to the direct current quantity of the input current as the front-end inductance.
11. The on-line identification device of claim 10 wherein the step of the processor calculating the front-end inductance further comprises:
respectively low-pass filtering the flux linkage difference direct current quantity and the input current direct current quantity; wherein
The step of the processor calculating the ratio further comprises:
and calculating the ratio of the flux linkage difference direct current quantity after the low-pass filtering treatment to the input current direct current quantity to be the front-end inductor.
12. The online identification device of claim 8, wherein the step of the processor obtaining the input voltage further comprises:
acquiring a switching function of the converter and a direct-current voltage at the rear end of the converter; and
and calculating the product of the switching function and the direct current voltage as the input voltage.
13. The online identification device of claim 8, wherein the processor integrates the secondary ac voltage and the input voltage to obtain the grid-side flux linkage and the ac-side flux linkage, respectively.
14. The online identification device of claim 13, wherein the integration operation is an anti-bias integration operation.
15. An online identification circuit for secondary side leakage reactance of a transformer, wherein a secondary side winding of the transformer is connected with a current transformer, and the online identification circuit comprises:
the first voltage sensor is used for acquiring secondary side alternating voltage of the transformer;
the second voltage sensor is used for acquiring the input voltage of the front end of the converter;
the current sensor is used for acquiring the input current of the front end of the converter;
an integrating circuit for simulating a grid-side flux linkage and an alternating-side flux linkage based on the secondary alternating-current voltage and the input voltage; and
and the division circuit is used for simulating the secondary side leakage reactance of the transformer based on the power grid side magnetic linkage, the alternating current side magnetic linkage and the input current.
16. The online identification circuit of claim 15, wherein the online identification circuit further comprises:
a subtraction circuit configured to calculate a flux linkage difference between the grid-side flux linkage and the ac-side flux linkage; wherein
The division circuit simulates the secondary side leakage reactance based on calculating the flux linkage difference and the input current.
17. The online identification circuit of claim 16, wherein the online identification circuit further comprises: the first low-pass filter and the amplifier are used for converting the flux linkage difference into flux linkage difference direct current quantity; and converting the input current to an input current dc quantity; wherein
The division circuit simulates the secondary side leakage reactance based on calculating the flux linkage difference direct current quantity and the input current direct current quantity.
18. The online identification circuit of claim 17, wherein the online identification circuit further comprises: the second low-pass filter is used for low-pass filtering the flux linkage difference direct current quantity and the input current direct current quantity; wherein
And the division circuit simulates the secondary side leakage reactance based on the flux linkage difference direct current quantity and the input current direct current quantity which are subjected to the low-pass filtering.
19. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the online identification method according to any one of claims 1 to 7.
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