CN114740272A - Bus capacitance online monitoring method, device, equipment and storage medium - Google Patents

Bus capacitance online monitoring method, device, equipment and storage medium Download PDF

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CN114740272A
CN114740272A CN202210406630.3A CN202210406630A CN114740272A CN 114740272 A CN114740272 A CN 114740272A CN 202210406630 A CN202210406630 A CN 202210406630A CN 114740272 A CN114740272 A CN 114740272A
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bus
current
voltage
equivalent circuit
capacitance
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CN114740272B (en
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赵朝阳
耿安琪
陶宏伟
胡海涛
何正友
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Southwest Jiaotong University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2605—Measuring capacitance
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Abstract

The application relates to a bus capacitor online monitoring method, a bus capacitor online monitoring device, bus capacitor online monitoring equipment and a storage medium, and belongs to the technical field of capacitor monitoring. The bus capacitance online monitoring method comprises the following steps: acquiring bus reference voltage and a plurality of groups of sampling values, wherein each group of sampling values comprises an average value of bus current and bus voltage; acquiring a preset transient equivalent circuit model; extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor. By the method, the bus capacitor can be monitored simply and conveniently without an additional isolation amplifying circuit.

Description

Bus capacitance on-line monitoring method, device, equipment and storage medium
Technical Field
The present disclosure relates to the field of capacitance monitoring technologies, and in particular, to a method, an apparatus, a device, and a storage medium for on-line monitoring of a bus capacitance.
Background
A typical configuration of an AC-DC power converter system with a direct-current link (DC-link) support capacitor is shown in fig. 1, and the most common application topologies include AC-DC cascaded converter (rectification) and DC-AC cascaded converter (inversion), and the application covers many fields including photovoltaic systems, motor drivers, electric vehicles, and lighting systems. The dc bus capacitor is a key component, and is often used to balance harmonics, suppress ripples, store energy for a short time, and the like. However, capacitance is one of the weakest links in a converter system. Statistics show that more than 30% of converter failures are caused by capacitive failures. The high failure rate of the direct-current bus capacitor brings great potential risks to the converter system, and the system is very easy to shut down unplanned, so that serious safety accidents and economic losses are caused.
Research shows that aging characteristic parameters (such as Equivalent Series Resistance (ESR), capacitance value and the like) of the capacitor change along with the degradation of the capacitor. The aging characteristic parameters of the capacitor in the converter are monitored on line, so that the health state assessment and failure early warning of elements can be realized, and the safe and reliable operation of the system is further guaranteed. Therefore, the bus capacitor is monitored on line, the health state of the bus capacitor is predicted, and the bus capacitor is maintained before serious degradation and failure occur, so that the bus capacitor has important significance for ensuring the reliable operation of a power converter and a power supply system.
However, the existing monitoring method is complex in sampling and signal processing, and generally needs an additional isolation amplifying circuit, which is not beneficial to implementation.
Disclosure of Invention
In order to solve the technical problem of monitoring the bus capacitor simply and conveniently, the application provides a bus capacitor online monitoring method, a bus capacitor online monitoring device, bus capacitor online monitoring equipment and a storage medium.
In a first aspect, the present application provides a method for online monitoring of a bus capacitor, where the method includes:
acquiring bus reference voltage and a plurality of groups of sampling values, wherein each group of sampling values comprises an average value of bus current and bus voltage;
acquiring a preset transient equivalent circuit model;
extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor;
further, extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model, including:
acquiring a parameter identification algorithm;
extracting equivalent circuit parameters based on the parameter identification algorithm according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the parameter identification algorithm comprises at least one of a recursive least square method, a Kalman filtering, a genetic algorithm and a neural network; the equivalent circuit parameters comprise equivalent inductance, equivalent resistance and the direct current bus capacitance value;
further, the transient equivalent circuit model includes:
ΔVdc(t)＝X×e-αt×sin(ωdt)
Figure BDA0003602175580000021
Figure BDA0003602175580000022
Figure BDA0003602175580000023
Figure BDA0003602175580000024
wherein, VdcIs the bus voltage, Δ VdcFor bus voltage VdcAnd bus reference voltage VrefDifference of (a), X, omegadAlpha and omega0Is an intermediate variable, LeqIs an equivalent inductance, ReqIs an equivalent resistance, CdcIs a bus barDirect current bus capacitance value of capacitor i'rearIs the average value of the bus current, Δ i'rearIs i'rearDifference from steady state current signal before transient;
further, the bus voltage is acquired through a voltage sensor; the average value of the bus current is based on the bus current and is obtained through an average value circuit; the bus current is collected through a current sensor; the current sensor is an inductive tunnel magnetoresistive current sensor;
further, obtaining an average value of the bus current includes:
acquiring a steady-state sampling threshold value and a transient-state sampling threshold value;
when the absolute value of the difference value between the bus voltage and the bus reference voltage is smaller than the steady-state sampling threshold value, acquiring a steady-state current signal corresponding to the current switching period;
when the bus voltage is greater than the transient sampling threshold value, acquiring a transient current signal corresponding to the current switching period;
obtaining the average value of the bus current according to the steady-state current signal and the transient current signal;
further, the method further comprises:
acquiring a capacitance reference value corresponding to a bus capacitance and a capacitance health state evaluation standard;
and determining the health state of the bus capacitor according to the capacitance reference value, the direct-current bus capacitance value and the capacitance health state evaluation standard.
In a second aspect, the present application provides an online bus capacitance monitoring device, comprising:
the system comprises a first acquisition module, a second acquisition module and a third acquisition module, wherein the first acquisition module is used for acquiring bus reference voltage and a plurality of groups of sampling values, and each group of sampling values comprises an average value of bus current and bus voltage;
the second acquisition module is used for acquiring a preset transient equivalent circuit model;
the extraction module is used for extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor.
In a third aspect, the present application provides a bus capacitance online monitoring device, including: the device comprises a voltage sampling unit, a current sampling unit, a micro control unit, a self-powered circuit and an upper computer;
the voltage sampling unit is used for acquiring bus voltage and bus reference voltage and sending the bus voltage and the bus reference voltage to the micro control unit;
the current sampling unit is used for acquiring the average value of the bus current and sending the average value to the micro control unit;
the micro control unit is used for sending the average values of the bus voltage, the bus reference voltage and the bus current to the upper computer;
the upper computer is used for extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and a transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor;
the self-powered circuit is used for supplying power to the voltage sampling unit, the current sampling unit and the micro-control unit.
In a fourth aspect, the present application provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, where the processor, the communication interface, and the memory complete communication with each other through the communication bus;
a memory for storing a computer program;
and the processor is used for realizing the steps of the bus capacitor online monitoring method in any embodiment of the first aspect when executing the program stored in the memory.
In a fifth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the bus capacitance online monitoring method according to any embodiment of the first aspect.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
according to the method provided by the embodiment of the application, bus reference voltage and a plurality of groups of sampling values are obtained, wherein each group of sampling values comprises the average value of bus current and bus voltage; acquiring a preset transient equivalent circuit model; extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor. By the method, the bus capacitor can be monitored simply and conveniently without an additional isolation amplifying circuit, and the convenience of on-line monitoring is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a diagram of a typical application of a DC bus capacitor in the prior art;
fig. 2 is a schematic diagram of a transient trajectory-based bus support capacitance monitoring scheme according to an embodiment of the present disclosure;
fig. 3 is a schematic flow chart of a bus capacitor online monitoring method according to an embodiment of the present disclosure;
fig. 4 is a scene diagram of an online monitoring method using a bus capacitor according to an embodiment of the present disclosure;
fig. 5 is a schematic diagram of a hardware structure of an online monitoring method using a bus capacitor according to an embodiment of the present disclosure;
fig. 6 is a schematic flow chart of another bus capacitor online monitoring method according to an embodiment of the present disclosure;
fig. 7 is a schematic diagram of a three-phase interleaved boost topology according to an embodiment of the present disclosure;
fig. 8 is a simulation waveform diagram of a three-phase interleaved boost topology according to an embodiment of the present application;
fig. 9 is a parameter identification result of a three-phase interleaved boost topology structure according to an embodiment of the present disclosure;
fig. 10 is a schematic structural diagram of an on-line bus capacitor monitoring device according to an embodiment of the present disclosure;
fig. 11 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, 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 some 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.
A first embodiment of the present application provides a method for online monitoring of a bus capacitor, which may be applied to a system architecture as shown in fig. 2, where the system architecture at least includes a capacitor bank, a front stage and a rear stage, where the front stage and the rear stage may be any converters without limitation, and the method may be used to make the capacitor bank equivalent to a transient equivalent circuit, so as to simply and conveniently implement online monitoring of a capacitor of the capacitor bank, where V isdcAnd i'rearTwo curves to show that the bus voltage V can be acquired from the positiondcAnd average value of bus Current i'rearCurve (c) of (d).
For real-time online state monitoring of the dc bus capacitor, the method can be classified into a white box method, a black box method and a gray box method according to an implementation method, and a typical case is shown in table 1, for example. As can be seen from table 1, the white-box method depends on the topology, operation mode and control strategy of the converter, and cannot apply the parameter identification model to other types of converters. The black box method requires a large amount of training data and is complex to implement. The steady state ripple and the switch ringing in the gray-box method have the characteristics of high frequency and small amplitude, but a high-frequency sampling device and equipment are required, and the complexity of monitoring the state of the capacitor is increased.
TABLE 1
Figure BDA0003602175580000041
The method for monitoring the gray box based on the capacitance state of the transient response model is provided, an equivalent circuit model of transient response characteristics of a converter is established, and bus capacitance parameters can be deduced by using the transient equivalent circuit. The state monitoring of the capacitor can be realized only by knowing the connection structure of the converter system without knowing the topological structure, the operation mode and the control strategy of the converter, and the method is a universal method. Next, the bus capacitance on-line monitoring method of the present application will be described in detail.
A bus capacitance online monitoring method, as shown in FIG. 3, includes:
step 301, obtaining a bus reference voltage and a plurality of groups of sampling values, wherein each group of sampling values comprises an average value of bus current and bus voltage.
Step 302, a preset transient equivalent circuit model is obtained.
Step 303, extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor.
According to the method, the capacitor bank is equivalent to a transient equivalent circuit, and the direct-current bus capacitance value can be extracted through a transient equivalent circuit model according to the average value of the bus current, the bus voltage and the bus reference voltage, so that the on-line monitoring of the bus capacitance is realized. The method is simple and convenient without additionally adding an isolation amplifying circuit, does not limit the front-stage circuit and the rear-stage circuit, can be suitable for different converters and load working conditions, does not need to know the topological structure, the operation mode and the control strategy of the converter, can realize the state monitoring of the bus capacitor only by knowing the connection structure of a converter system, such as the installation position of the capacitor, and has universality.
In one embodiment, extracting the equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model comprises: acquiring a parameter identification algorithm; extracting equivalent circuit parameters based on a parameter identification algorithm according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the parameter identification algorithm comprises at least one of a recursive least square method, a Kalman filtering method, a genetic algorithm and a neural network; the equivalent circuit parameters comprise equivalent inductance, equivalent resistance and direct current bus capacitance.
In this embodiment, the equivalent circuit parameters in the transient equivalent circuit model, such as equivalent inductance, equivalent resistance, and dc bus capacitance, can be extracted from the average value of the bus current, the bus voltage, and the bus reference voltage through a parameter identification algorithm. The health state of the bus capacitor can be determined according to the capacitance value of the direct current bus, maintenance can be carried out before the bus capacitor is seriously degraded and failed, and the method has important significance for ensuring the reliable operation of a system applying the bus capacitor, such as a power converter, a power supply system and the like.
In one embodiment, a transient equivalent circuit model includes:
ΔVdc(t)＝X×e-αt×sin(ωdt) (1)
Figure BDA0003602175580000051
Figure BDA0003602175580000052
Figure BDA0003602175580000053
Figure BDA0003602175580000054
wherein, VdcIs the bus voltage, Δ VdcFor bus voltage VdcAnd bus reference voltage VrefDifference of (e), X, omegadAlpha and omega0Is an intermediate variable, LeqIs an equivalent inductance, ReqIs an equivalent resistance, CdcIs a DC bus capacitance value of a bus capacitance i'rearIs the average value of the bus current, Δ i'rearIs i'rearDifference from the steady state current signal before the transient.
Based on the proposed concept of transient equivalence, the implementation scheme of bus capacitance state monitoring is shown in fig. 4. The bus voltage is acquired through a voltage sensor, and the bus current is acquired through a current sensor. In order to not destroy the structure of the original circuit, an inductive tunnel magnetoresistive current sensor can be adopted for collecting bus current. It should be noted that the tunnel magnetoresistive current sensor is an implementation manner of the embodiment of the present application that does not destroy the structure of the original circuit, and does not represent a limitation on the current sensor, and other current sensors may also be used.
In one embodiment, the bus voltage is collected by a voltage sensor; the average value of the bus current is based on the bus current and is obtained through an average value circuit; the bus current is collected by a current sensor.
In this embodiment, a detailed schematic diagram of a hardware scheme of the bus capacitance online monitoring device is shown in fig. 5, where the bus capacitance online monitoring device includes: the device comprises a voltage sampling unit, a current sampling unit, a micro control unit, a self-powered circuit and an upper computer;
the voltage sampling unit is used for acquiring bus voltage and bus reference voltage and sending the bus voltage and the bus reference voltage to the micro control unit;
the current sampling unit is used for acquiring the average value of the bus current and sending the average value to the micro control unit;
the micro control unit is used for sending the average values of the bus voltage, the bus reference voltage and the bus current to an upper computer;
the upper computer is used for extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor;
and the self-power supply circuit is used for supplying power to the voltage sampling unit, the current sampling unit and the micro-control unit.
Wherein B represents magnetic induction intensity, MCU is a micro control unit, ADC is an analog-to-digital conversion unit inside MCU, and SCI is a serial port communication unit of MCU. Taking into account the current of the subsequent stage (bus current) i in a cascaded converter systemrearIs a pulsating current and is not easy to sample. Therefore, the sampled post-stage current is processed by a mean value circuit to obtain a mean value i'rearAnd the average value circuit consists of a resistor Rav and a capacitor Cav. In addition, the MCU sends the acquired voltage and current data to the upper computer through the SCI for parameter identification and health status evaluation. The voltage sampling unit can be a Hall sensor, the self-power circuit is used for supplying power to the voltage sampling unit, the current sampling unit (the tunnel magnetoresistive sensor and the average circuit) and the MCU, plug and play of the bus capacitor online monitoring device can be achieved, an additional power supply is not needed, and the use is more convenient.
In one embodiment, obtaining an average value of the bus current comprises: acquiring a steady-state sampling threshold value and a transient-state sampling threshold value; when the absolute value of the difference value between the bus voltage and the bus reference voltage is smaller than a steady-state sampling threshold value, acquiring a steady-state current signal corresponding to the current switching period; when the bus voltage is greater than the transient sampling threshold value, acquiring a transient current signal corresponding to the current switching period; and obtaining the average value of the bus current according to the steady-state current signal and the transient current signal.
By setting a steady-state sampling threshold value and a transient-state sampling threshold value, when the conditions are met, sampling values are obtained respectively, the bus current is sampled, the average value of the bus current is obtained, and an accurate data basis is provided for on-line monitoring of the bus capacitor.
In one embodiment, the method further comprises: acquiring a capacitance reference value corresponding to a bus capacitance and a capacitance health state evaluation standard; and determining the health state of the bus capacitor according to the capacitance reference value, the capacitance value of the direct current bus and the evaluation standard of the health state of the capacitor.
In this embodiment, after the capacitance value of the dc bus is extracted according to the transient equivalent circuit model, the capacitance reference value and the capacitance health state evaluation standard of the bus capacitor are obtained, the health state of the bus capacitor is evaluated, the health state of the bus capacitor is predicted, maintenance can be prompted before serious degradation and failure of the bus capacitor occurs, health state evaluation and failure early warning of the bus capacitor are achieved, and safe and reliable operation of the system is further guaranteed. For example, if the extracted capacitance value of the dc bus is 90 μ F, the capacitance reference value of the bus capacitor is 100 μ F, and the evaluation criterion of the health state of the capacitor is that the state of health in which the actual capacitance value is greater than 80% of the capacitance reference value is a state of health in which the bus capacitor can be normally used, it can be determined that the health state of the bus capacitor is normal. It should be noted that the above capacitance health state evaluation criterion of 80% is only an example, and may be adjusted according to the importance degree of the actual application scenario in the specific application, without limitation.
In this embodiment, the detailed parameter estimation process is shown in fig. 6, and mainly includes two parts, namely, data acquisition and state estimation. Data acquisition is performed by firstly sampling VdcAnd i'rearWhen | Vdc-Vref|＜ΔVth1The time system collects the steady state current signal, records the steady state data, when Vdc＞Vth2The time system collects the transient current signal and records the transient data, wherein, the transient data is DeltaVth1For steady state sampling threshold, Vth2Is the transient sampling threshold. The state estimation comprises Δ V calculation, Δ I estimation, parameter identification and state estimation, wherein the Δ V calculation means that Δ V ═ V is performeddc-VrefThe Δ I estimation means that the calculation of Δ I — I1-I2 is performed, wherein I2 represents the acquired transient current signal, and I1 represents the steady-state current signal before the acquisition of I2. Then, based on the formula (1), the formula (2), the formula (3), the formula (4) and the formula (5), parameters of the RLC equivalent circuit are obtained by using a parameter identification algorithm such as least square, neural network and the like, and parameters of the equivalent circuit such as direct current bus capacitance value are obtained according to the parameters of the equivalent circuitAnd evaluating the state of the bus capacitor.
In one embodiment, the average value of the bus current may also be calculated by collecting the phase current and the sampling time. For example, when the method is applied to an ac-dc motor driver, the average value of the bus current is obtained, which includes:
acquiring a first stator phase current, a second stator phase current and a third stator phase current, and acquiring sampling time;
acquiring the conduction time of a first bridge arm tube corresponding to the first stator phase current, acquiring the conduction time of a second bridge arm tube corresponding to the second stator phase current, and acquiring the conduction time of a third bridge arm tube corresponding to the third stator phase current;
and obtaining the average value of the bus current according to the first stator phase current, the second stator phase current, the third stator phase current, the first bridge arm top tube conduction time, the second bridge arm top tube conduction time, the third bridge arm top tube conduction time and the sampling time.
In this embodiment, specifically, obtaining an average value of the bus current according to the first stator phase current, the second stator phase current, the third stator phase current, the first bridge arm tube conduction time, the second bridge arm tube conduction time, the third bridge arm tube conduction time, and the sampling time includes:
Figure BDA0003602175580000071
wherein isaIs a first stator phase current isbFor the second stator phase current, iscFor the third stator phase current, TsaFor the conduction time of the upper tube of the first bridge arm, TsbFor the conduction time of the upper tube of the first bridge arm, TscFor the conduction time of the upper tube of the first bridge arm, TsIs the sampling time, i'rearIs the average value of the bus current.
I 'calculated by formula (6)'rearIn combination with acquired VdcAnd the direct-current bus capacitance value can be obtained through the formulas (1) to (5), so that the on-line monitoring of the bus capacitance is realized.
Note that i 'in the above examples'rearThe average value of the bus current over a period of time may be a curve of values corresponding to a plurality of switching cycles, VdcSimilarly, the bus voltage over a period of time is represented.
In order to verify the feasibility of the bus capacitor online monitoring method, a three-phase interleaved boost converter is taken as an example, and fig. 7 shows a topological structure of the three-phase interleaved boost converter. Fig. 8 shows a simulation waveform, which is identified by using the transient simulation waveform and any one of the parameter identification algorithms, for example, the least square algorithm, and the result of the parameter identification is shown in fig. 9. Fig. 9 also shows the waveform result of the parameter reverse-estimation obtained by identification, and it can be seen that the waveform result of the parameter reverse-estimation obtained by identification matches the original waveform, i.e. the feasibility of the method is proved.
Based on the same technical concept, a second embodiment of the present application provides an on-line bus capacitance monitoring device, as shown in fig. 10, including:
the first obtaining module 1001 is configured to obtain a bus reference voltage and multiple groups of sampling values, where each group of sampling values includes an average value of a bus current and a bus voltage;
a second obtaining module 1002, configured to obtain a preset transient equivalent circuit model;
an extracting module 1003, configured to extract an equivalent circuit parameter according to the average value of the bus current, the bus voltage, the bus reference voltage, and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor.
The monitoring device enables the capacitor bank to be equivalent to a transient equivalent circuit, the first acquisition module acquires the average value of the bus current, the bus voltage and the bus reference voltage, the extraction module can extract the direct-current bus capacitance value according to the transient equivalent circuit model acquired by the second acquisition module, and online monitoring of the bus capacitance is achieved. The device does not need to additionally increase an isolation amplifying circuit, is simple and convenient, does not limit a preceding-stage circuit and a rear-stage circuit, can be suitable for different converters and load working conditions, does not need to know the topological structure, the operation mode and the control strategy of the converter, only needs to know the connection structure of a converter system, such as the installation position of a capacitor, can realize the state monitoring of a bus capacitor, and has universality.
As shown in fig. 11, a third embodiment of the present application provides an electronic device, which includes a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 complete mutual communication via the communication bus 114,
a memory 113 for storing a computer program;
in an embodiment, the processor 111, when executing the program stored in the memory 113, is configured to implement the method for online monitoring of bus capacitance provided in any one of the foregoing method embodiments, and includes:
acquiring bus reference voltage and a plurality of groups of sampling values, wherein each group of sampling values comprises an average value of bus current and bus voltage;
acquiring a preset transient equivalent circuit model;
extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor.
The communication bus mentioned in the above terminal may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus.
The communication interface is used for communication between the terminal and other equipment.
The Memory may include a Random Access Memory (RAM) or a non-volatile Memory (non-volatile Memory), such as at least one disk Memory. Optionally, the memory may also be at least one memory device located remotely from the processor.
The Processor may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; the Integrated Circuit may also be 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 device, or discrete hardware components.
The fourth embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the bus capacitor online monitoring method provided in any one of the foregoing method embodiments.
In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that includes one or more available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.
It is noted that, in this document, relational terms such as "first" and "second," and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, 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 identical elements in a process, method, article, or apparatus that comprises the element.
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In the description, suffixes such as "module", "part", or "unit" used to indicate elements are used only for facilitating the description of the present invention, and have no particular meaning in itself. Thus, "module", "component" or "unit" may be used mixedly.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A bus capacitance online monitoring method is characterized by comprising the following steps:
acquiring bus reference voltage and a plurality of groups of sampling values, wherein each group of sampling values comprises an average value of bus current and bus voltage;
acquiring a preset transient equivalent circuit model;
extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor.
2. The method of claim 1, wherein extracting equivalent circuit parameters from the average value of the bus current, the bus voltage, the bus reference voltage, and the transient equivalent circuit model comprises:
acquiring a parameter identification algorithm;
extracting equivalent circuit parameters based on the parameter identification algorithm according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the parameter identification algorithm comprises at least one of a recursive least square method, a Kalman filtering, a genetic algorithm and a neural network; the equivalent circuit parameters comprise equivalent inductance, equivalent resistance and the direct current bus capacitance value.
3. The method of claim 1 or 2, wherein the transient equivalent circuit model comprises:
ΔVdc(t)＝X×e-αt×sin(ωdt)
Figure FDA0003602175570000011
Figure FDA0003602175570000012
Figure FDA0003602175570000013
Figure FDA0003602175570000014
wherein, VdcIs the bus voltage, Δ VdcIs the bus voltage VdcAnd bus reference voltage VrefDifference of (e), X, omegadAlpha and omega0Is an intermediate variable, LeqIs an equivalent inductance, ReqIs an equivalent resistance, CdcIs a DC bus capacitance value of a bus capacitance i'rearIs the average value of the bus current, Δ i'rearIs i'rearDifference from the steady state current signal before the transient.
4. The method of claim 1, wherein the bus voltage is collected by a voltage sensor; the average value of the bus current is based on the bus current and is obtained through an average value circuit; the bus current is collected through a current sensor; the current sensor is an inductive tunnel magnetoresistive current sensor.
5. The method of claim 1, wherein obtaining an average value of bus current comprises:
acquiring a steady-state sampling threshold value and a transient-state sampling threshold value;
when the absolute value of the difference value between the bus voltage and the bus reference voltage is smaller than the steady-state sampling threshold value, acquiring a steady-state current signal corresponding to the current switching period;
when the bus voltage is greater than the transient sampling threshold value, acquiring a transient current signal corresponding to the current switching period;
and obtaining the average value of the bus current according to the steady-state current signal and the transient current signal.
6. The method of claim 1, further comprising:
acquiring a capacitance reference value corresponding to a bus capacitor and a capacitance health state evaluation standard;
and determining the health state of the bus capacitor according to the capacitance reference value, the direct-current bus capacitance value and the capacitance health state evaluation standard.
7. A bus capacitance on-line monitoring device, characterized in that the device includes:
the system comprises a first acquisition module, a second acquisition module and a third acquisition module, wherein the first acquisition module is used for acquiring bus reference voltage and a plurality of groups of sampling values, and each group of sampling values comprises an average value of bus current and bus voltage;
the second acquisition module is used for acquiring a preset transient equivalent circuit model;
the extraction module is used for extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and the transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor.
8. A bus capacitance on-line monitoring device, characterized in that the device comprises: the device comprises a voltage sampling unit, a current sampling unit, a micro control unit, a self-powered circuit and an upper computer;
the voltage sampling unit is used for acquiring bus voltage and bus reference voltage and sending the bus voltage and the bus reference voltage to the micro control unit;
the current sampling unit is used for acquiring the average value of the bus current and sending the average value to the micro control unit;
the micro control unit is used for sending the average values of the bus voltage, the bus reference voltage and the bus current to the upper computer;
the upper computer is used for extracting equivalent circuit parameters according to the average value of the bus current, the bus voltage, the bus reference voltage and a transient equivalent circuit model; the equivalent circuit parameters at least comprise a direct current bus capacitance value of the bus capacitor;
the self-powered circuit is used for supplying power to the voltage sampling unit, the current sampling unit and the micro-control unit.
9. An electronic device is characterized by comprising a processor, a communication interface, a memory and a communication bus, wherein the processor and the communication interface are used for realizing mutual communication by the memory through the communication bus;
a memory for storing a computer program;
a processor for implementing the steps of the bus capacitance online monitoring method according to any one of claims 1 to 6 when executing the program stored in the memory.
10. 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 method for on-line monitoring of a bus capacitance according to any one of claims 1 to 6.
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