CN-121831275-B - Power module capacitor capacitance value estimation method, device, medium and equipment

CN121831275BCN 121831275 BCN121831275 BCN 121831275BCN-121831275-B

Abstract

According to the power module capacitor capacitance value estimation method, device, medium and equipment provided by the application, the reference voltages of the capacitor voltage sequence in the stabilizing section and the calibration section are calculated respectively, the references are established in the stabilizing section and the calibration section respectively to determine the reference drift amount, and the original voltage change value is dynamically corrected based on the reference drift amount to obtain a more accurate target voltage change value. Meanwhile, a sectional weighted integral is introduced to the processing of the bridge arm current sequence, and the current weighted integral is calculated according to different dynamic characteristics of the transition section and the input stable section, so that the current integral can more truly reflect the actual energy storage change of the capacitor, and the accuracy of a target current value is further ensured. Finally, the two optimized key physical quantities are used for calculating the capacitance value, so that the result is closer to the actual state of the capacitor. In the process, by means of the structured signal segmentation and dynamic correction strategy, the real-time response capability of the capacity value estimation method is enhanced while high estimation accuracy is guaranteed.

Inventors

HUANG YIHONG
ZOU CHANGYUE
LUO YI
QU ZUOMIN
ZHANG LE
XU JIDONG
HOU TING
LI LINGFEI
CHEN YUEXIAN
GUAN XISHENG
Shi Youjie
LU YIPING
LUO WENBO
PAN KUNNIAN

Assignees

南方电网科学研究院有限责任公司
广东电网有限责任公司阳江供电局

Dates

Publication Date: 20260512
Application Date: 20260316

Claims (10)

1. A method for estimating a capacitance of a capacitor of a power module, the method comprising: Acquiring a bridge arm current sequence and a capacitor voltage sequence of a power module to be tested in a period of time, and determining a target switching stage in the period of time, wherein the target switching stage comprises a stabilizing section, a transition section, a switching stabilizing section and a calibration section; Respectively calculating reference voltages of the capacitor voltage sequence in the stable section and the calibration section to obtain a stable section reference voltage and a calibration section reference voltage; Determining original voltage change values of the power module to be tested before and after the input of the target switching stage, and correcting the original voltage change values based on the reference voltage of the stable section and the reference voltage of the calibration section to obtain a target voltage change value; Respectively calculating the current weighted integral of the bridge arm current sequence in the transition section and the input stable section to determine a target current value; and determining the capacitor capacity value of the power module to be tested at the current moment according to the target voltage change value and the target current value.
2. The method for estimating a capacitor capacitance of a power module according to claim 1, wherein the step of obtaining a bridge arm current sequence and a capacitor voltage sequence of the power module to be measured in a period of time includes: Collecting bridge arm current data and capacitance voltage sequences of a power module to be tested within a period of time; carrying out forward Newton interpolation processing on the bridge arm current data so as to enable the processed bridge arm current data to be matched with the sampling frequency of the capacitor voltage sequence; and generating a bridge arm current sequence according to the processed bridge arm current data.
3. The power module capacitor capacitance estimation method according to claim 1, wherein calculating the reference voltages of the capacitor voltage sequence in the stable section and the calibration section, respectively, to obtain a stable section reference voltage and a calibration section reference voltage, includes: Extracting a first voltage sequence of the capacitor voltage sequence in the stable section, and calculating an average value of the first voltage sequence to obtain a reference voltage of the stable section; And extracting a second voltage sequence of the capacitor voltage sequence in the calibration section, and calculating an average value of the second voltage sequence to obtain a reference voltage of the calibration section.
4. The power module capacitor capacity estimation method according to claim 1, wherein the determining the original voltage change value of the power module to be tested before and after the input of the target switching stage includes: Determining an end point of the input stable segment of the target switching stage; And carrying out difference on the voltage value corresponding to the capacitor voltage sequence between the end point of the input stabilizing section and the end point of the stabilizing section to obtain an original voltage change value.
5. The power module capacitor capacitance estimation method according to claim 1, wherein the correcting the original voltage variation value based on the stable segment reference voltage and the calibration segment reference voltage to obtain a target voltage variation value includes: Calculating an absolute value of a difference between the calibration segment reference voltage and the stable segment reference voltage; If the absolute value is not greater than a preset threshold value, determining the difference between the reference voltage of the calibration segment and the reference voltage of the stable segment as a voltage correction value, otherwise, acquiring a historical average reference of the stable segment and a historical average reference of the calibration segment, and determining the difference between the calibration segment and the historical average reference of the stable segment as the voltage correction value; And after the voltage correction value is determined, correcting the original voltage change value based on the voltage correction value to obtain a corrected voltage change value, determining the proportion of the input stable section of the voltage change to the sum of the transition section and the input stable section, and carrying out secondary correction on the corrected voltage change value based on the proportion to obtain a target voltage change value.
6. The power module capacitor capacitance estimation method according to claim 1, wherein the calculating the current weighted integration of the bridge arm current sequence in the transition section and the input stabilizing section to determine the target current value includes: Acquiring a current compensation coefficient of the transition section and a current compensation coefficient of the input stable section, and extracting a first current sequence of the bridge arm current sequence in the transition section and a second current sequence of the bridge arm current sequence in the input stable section; And integrating the first current sequence and the second current sequence to obtain a first current integral and a second current integral, and respectively carrying out weighted summation on the first current integral and the second current integral by utilizing the current compensation coefficient of the transition section and the current compensation coefficient of the input stabilizing section to obtain a target current value.
7. The power module capacitor capacity estimation method according to any one of claims 1 to 6, wherein the determining the capacitor capacity of the power module to be measured at the current time according to the target voltage variation value and the target current value includes: calculating the quotient of the target current value and the target voltage change value, and determining the calculation result as a preliminary capacitor capacitance value; And acquiring capacitor capacitance values of the first N times at the current time, and carrying out moving average filtering processing on the preliminary capacitor capacitance values according to the capacitor capacitance values of the first N times to obtain the capacitor capacitance value of the power module to be tested at the current time.
8. A power module capacitor capacitance estimation apparatus, the apparatus comprising: The system comprises a data acquisition module, a target switching stage, a calibration module and a control module, wherein the data acquisition module is used for acquiring a bridge arm current sequence and a capacitor voltage sequence of a power module to be tested in a period of time and determining the target switching stage in the period of time; the voltage calculation module is used for respectively calculating the reference voltages of the capacitor voltage sequence in the stable section and the calibration section to obtain the reference voltage of the stable section and the reference voltage of the calibration section; The voltage correction module is used for determining original voltage change values of the power module to be tested before and after the power module is put into the target switching stage, and correcting the original voltage change values based on the reference voltage of the stable section and the reference voltage of the calibration section to obtain a target voltage change value; the current calculation module is used for calculating the current weighted integration of the bridge arm current sequence in the transition section and the input stable section respectively so as to determine a target current value; And the capacitance value determining module is used for determining the capacitance value of the capacitor of the power module to be tested at the current moment according to the target voltage change value and the target current value.
9. A storage medium having stored therein computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of the power module capacitor capacitance estimation method of any one of claims 1 to 7.
10. A computer device includes one or more processors and a memory; stored in the memory are computer readable instructions which, when executed by the one or more processors, perform the steps of the power module capacitor capacitance estimation method of any one of claims 1 to 7.

Description

Power module capacitor capacitance value estimation method, device, medium and equipment Technical Field The present application relates to the field of power electronics technologies, and in particular, to a method, an apparatus, a medium, and a device for estimating a capacitance value of a capacitor of a power module. Background The modularized multi-level converter is used as core equipment in the fields of high-voltage direct-current transmission, new energy grid connection and the like, and the high reliability and the superior electric energy quality of the modularized multi-level converter are highly dependent on the normal operation of the sub-modules. The capacitor in the sub-module is used as a key energy storage element, the capacity value is easy to be reduced due to aging in long-term operation, and once the capacity value is obviously attenuated, the energy storage performance of the sub-module is directly affected, even a system fault is caused, so that the capacitor capacity value is accurately monitored and estimated in real time. Currently, methods for estimating capacitance of a capacitor are mainly divided into two approaches based on a model and based on signal processing. The former estimates the capacitance voltage by means of self-adaptive algorithm by establishing a voltage model of the sub-module, so as to calculate the capacitance value, but the method relies on an accurate mathematical model and has strict requirements on parameter accuracy. The latter directly calculates the capacitance value according to the current and voltage sampling signals of the capacitor and suppresses noise interference by means of a filtering algorithm, however, the noise filtering algorithm adopted by the method is complex in structure and difficult to meet the requirement on real-time processing capability. On the other hand, the capacitance value calculation formula is unified, and the matching degree between the voltage change and the current integration is insufficient, so that the accuracy of the estimation result is influenced. In summary, the capacitor capacitance estimation method in the prior art is difficult to meet the requirements of real-time performance and accuracy. Disclosure of Invention The present application aims to solve at least one of the above technical drawbacks, and in particular, the technical drawbacks of the capacitor capacitance estimation method in the prior art that it is difficult to meet the requirements of real-time performance and accuracy. In a first aspect, the present application provides a method for estimating a capacitance value of a capacitor of a power module, the method comprising: Acquiring a bridge arm current sequence and a capacitor voltage sequence of a power module to be tested in a period of time, and determining a target switching stage in the period of time, wherein the target switching stage comprises a stabilizing section, a transition section, a switching stabilizing section and a calibration section; Respectively calculating reference voltages of the capacitor voltage sequence in the stable section and the calibration section to obtain a stable section reference voltage and a calibration section reference voltage; Determining original voltage change values of the power module to be tested before and after the input of the target switching stage, and correcting the original voltage change values based on the reference voltage of the stable section and the reference voltage of the calibration section to obtain a target voltage change value; Respectively calculating the current weighted integral of the bridge arm current sequence in the transition section and the input stable section to determine a target current value; and determining the capacitor capacity value of the power module to be tested at the current moment according to the target voltage change value and the target current value. In one embodiment, the obtaining the bridge arm current sequence and the capacitor voltage sequence of the power module to be tested in a period of time includes: Collecting bridge arm current data and a capacitor voltage sequence of a power module to be tested in a period of time; carrying out forward Newton interpolation processing on the bridge arm current data so as to enable the processed bridge arm current data to be matched with the sampling frequency of the capacitor voltage sequence; and generating a bridge arm current sequence according to the processed bridge arm current data. In one embodiment, the calculating the reference voltages of the capacitor voltage sequence in the stable segment and the calibration segment to obtain the stable segment reference voltage and the calibration segment reference voltage includes: Extracting a first voltage sequence of the capacitor voltage sequence in the stable section, and calculating an average value of the first voltage sequence to obtain a reference voltage of the stable section; And extracting a second vo