CN-115856703-B - Transformer traversing fault monitoring, evaluating and short circuit model correcting device and method

CN115856703BCN 115856703 BCN115856703 BCN 115856703BCN-115856703-B

Abstract

The invention belongs to the technical field of power engineering, and discloses a device and a method for monitoring, evaluating and correcting a short circuit model of a transformer penetrability fault, wherein the device comprises a data acquisition device, a data processing module, a fault identification module, a state evaluation module and a correction module; the data acquisition device acquires voltage and current signals of the transformer and the bus as digital signals, the data processing module analyzes the acquired voltage and current data, corrects or eliminates outlier and missing data, the fault identification module identifies the transformer crossing fault on the basis of the corrected data, the state evaluation module evaluates and early warns the state of the transformer, and the correction module performs checksum correction on the impedance value of the short circuit model. The invention realizes automatic correction of the external penetrability short circuit model by real-time monitoring data, and can evaluate and early warn faults of the transformer.

Inventors

TONG TAO
LI TANGBING
WAN HUA
TONG CHAO
WANG PENG
XU BICHUAN
ZENG LEILEI
ZHANG JING

Assignees

国网江西省电力有限公司电力科学研究院
国家电网有限公司
南昌科晨电力试验研究有限公司

Dates

Publication Date: 20260505
Application Date: 20221021

Claims (9)

1. A method for monitoring, evaluating and correcting a short circuit model of a transformer penetrating fault is characterized by comprising the following steps: Step one, a data acquisition device samples and collects the voltage transformer and the current transformer secondary side of the outgoing line side and the bus of the power transformer, and acquired data are transmitted to a data processing module for data processing; Step two, the data processing module judges that the data is outlier when the current signal or the voltage signal exceeds an outlier threshold compared with the predicted value according to each data point of the acquired digital signal, calculates an outlier interval and corrects or eliminates the outlier data; analyzing the corrected current and voltage data by a fault identification module to identify the transformer crossing fault, wherein the fault identification module is used for identifying the transformer crossing fault when the high, medium and low voltage side current and voltage of the transformer meet the requirement in a monitoring mode And is also provided with Judging that a penetrating short circuit fault occurs in the transformer, wherein k coil is the transformer winding transformation ratio, I H is the high-voltage side current of the transformer, U H/M/L is the voltage of any one side of high, medium and low voltages of the transformer, I M/L is the current of the medium and low voltages of the transformer, f s is the sampling rate set by a platform corresponding to the time t, f 0 is the rated frequency of the power system, q is the sampling point ordinal number, and t s is the fault starting time; Step four, a state evaluation module calculates overvoltage and crossing current of the transformer, and evaluates and early warns the state of the transformer, wherein the risk coefficient k r of the current crossing fault of the transformer is calculated according to the following formula: , Wherein the method comprises the steps of 、 For the times including the current time when the historical dynamic stability current ratio exceeds 80% and 20%, deltat d 、△t t is the current time duration of dynamic stability and thermal stability, k D is the current time ratio of the current time of cross-over fault short-circuit current and k T is the current time ratio of the current time of cross-over fault short-circuit current; And fifthly, correcting a short circuit model, namely checking and correcting an impedance value of the short circuit model and a maximum short circuit current model which can bear under dynamic and thermal stability according to the penetrating short circuit fault data, wherein the total impedance value Z a of the short circuit model is as follows: , Wherein t max is the moment of the maximum instantaneous value of the short-circuit current, Δt d is the short-circuit dynamic stability duration, U is the short-circuit side voltage transient value, and I is the short-circuit side current transient value.
2. The method for monitoring, evaluating and correcting a short-circuit model of a transformer according to claim 1, wherein in the first step, the sampling rate is dynamically changed along with waveform history characteristics, outlier data and feedback data of the crossing fault identification, and the data acquisition device has three modes of a basic mode, a monitoring mode and a fault recording mode according to different feedback data.
3. The method for monitoring, evaluating and correcting a short-circuit model for transformer penetrating faults as claimed in claim 1, wherein the processing procedure of the second step is specifically as follows: the predicted value at time t is: ; wherein t is time, fsig (t) and Sig (t) are respectively a predicted value and an actual measured value of t time data, p is a cycle prediction factor, and is determined by cycle fluctuation and calculated according to the following formula: ; Let t q be the single point outlier time or the collective outlier start time, t r be any time within the collective outlier time period, and k s 、k e be the outlier start value and the outlier return value respectively, when the time t q exists, the following is satisfied: Then, it is determined that the data at time t q is single-point outlier, and the outlier data is corrected to be ; Any time t r when there is a time period t q to t q +f 0 /f s satisfies: Then determining the collective outlier in the period from t q to t q +f 0 /f s , correcting the data in the collective outlier interval to be 。
4. The method for monitoring, evaluating and correcting a short-circuit model of transformer traversing faults as claimed in claim 3, wherein the specific process of the third step is as follows: For three-phase voltage/current data, when the current/voltage ramp coefficients simultaneously satisfy the following: ; Wherein r u is a voltage mutation coefficient, r i is a current mutation coefficient, U A/B/C and I A/B/C are respectively the phase voltage and current at the fault starting moment A, B, C, As the voltage step-up threshold value, Is a current abrupt threshold; The current signal and the voltage signal corresponding to the analysis data are judged to be abnormal, the fault identification module feeds back the data to the data acquisition device to enter a monitoring mode from a basic mode, and the sampling rate is adjusted to be not less than: ; Wherein f w 、f a is the reference frequency and the index frequency in the monitoring mode, respectively.
5. The method for monitoring, evaluating and correcting a short-circuit model of a transformer according to claim 4, wherein the fault recognition module feeds back a signal to the data acquisition device to enter a monitoring mode from a basic mode after the occurrence of the short-circuit, and adjusts the sampling rate to a maximum frequency.
6. The method for monitoring, evaluating and correcting a short-circuit model for transformer penetrating fault according to claim 5, wherein in step four, the calculation modes of k D and k T are as follows: ; ; T max is the maximum moment corresponding to the transformer current, I D is the maximum short-circuit current which can be borne under the dynamic stability of the transformer, and I T is the maximum short-circuit current which can be borne under the thermal stability of the transformer.
7. The method for monitoring, evaluating and correcting a short-circuit model of a transformer according to claim 1, wherein the maximum short-circuit current that can be sustained under the dynamic and thermal stability of the transformer is corrected as follows: ; Wherein, I D is the maximum short-circuit current that can be borne under the dynamic stability of the transformer, I T is the maximum short-circuit current that can be borne under the thermal stability of the transformer, and U m is the highest operating voltage of the short-circuit side of the transformer.
8. A device for realizing the transformer penetrability fault monitoring, evaluating and short circuit model correcting method according to any one of claims 1-7 is characterized by comprising a data acquisition device, a data processing module, a fault identification module, a state evaluation module and a correction module, wherein the data acquisition device is connected with a voltage transformer and a current transformer secondary wiring terminal of a power transformer outgoing line side and a bus and is used for acquiring voltage and current signals of the transformer and the bus into digital signals, the data processing module analyzes the acquired voltage and current data and corrects or eliminates outlier and missing data, the fault identification module identifies the transformer penetrability fault on the basis of the corrected data, the state evaluation module evaluates and early warns the state of the transformer, and the correction module verifies and corrects the impedance value of the short circuit model.
9. A non-volatile computer storage medium having stored thereon computer executable instructions for performing the transformer ride-through fault monitoring, evaluation and short circuit model correction method of any one of claims 1 to 7.

Description

Transformer traversing fault monitoring, evaluating and short circuit model correcting device and method Technical Field The invention belongs to the field of transformer state monitoring, and particularly relates to a device and a method for monitoring, evaluating and correcting a short circuit model of a transformer crossing fault. Background The transformer is used as a junction point and core equipment of the power system, and the reliable operation of the transformer directly affects the safety and stability of the power system. The protection of the transformer comprises differential protection and gas protection, mainly protects the internal or regional faults of the transformer, and the traversing faults caused by external short circuits to the transformer can also influence the stable operation of the transformer. The prior art mainly monitors the external operation state of the transformer through a fault wave recording device, and the fault wave recording device has certain defects when in use and needs to be improved. Firstly, the existing fault wave recording device cannot automatically identify the external short-circuit and other penetrability faults, the waveform is required to be read and judged manually, the difficulty of on-line work is increased, secondly, the existing fault wave recording device cannot automatically correct the external penetrability short-circuit model based on real-time monitoring data, the fault wave recording device does not have the functions of evaluating and early warning faults of the transformer, and the lean maintenance work of the transformer cannot be effectively guided. Disclosure of Invention The technical problems to be solved by the invention are that the existing fault wave recording device cannot automatically identify the penetrating faults such as external short circuits and the like, the waveform is required to be read and judged manually, the difficulty of one-line work is increased, and secondly, the existing transformer fault wave recording device cannot automatically correct the external penetrating short circuit model based on real-time monitoring data, does not have the functions of evaluating and early warning the faults of the transformer, and cannot effectively guide the lean maintenance work of the transformer. The technical scheme includes that the transformer traversing fault monitoring, evaluating and short circuit model correcting device comprises a data acquisition device, a data processing module, a fault identification module, a state evaluation module and a correcting module, wherein the data acquisition device is connected with a voltage transformer and a current transformer secondary wiring terminal of a power transformer outgoing line side and a bus and is used for acquiring voltage and current signals of the transformer and the bus into digital signals, the data processing module analyzes the acquired voltage and current data, corrects or eliminates outlier and missing data, the fault identification module identifies the transformer traversing fault on the basis of the corrected data, the state evaluation module evaluates and early warns the state of the transformer, and the correcting module checks and corrects the impedance value of the short circuit model. A method for monitoring, evaluating and correcting a short circuit model of a transformer penetrating fault comprises the following steps: Step one, a data acquisition device samples and collects the voltage transformer and the current transformer secondary side of the outgoing line side and the bus of the power transformer, and acquired data are transmitted to a data processing module for data processing; Step two, the data processing module judges that the data is outlier when the current signal or the voltage signal exceeds an outlier threshold compared with the predicted value according to each data point of the acquired digital signal, calculates an outlier interval and corrects or eliminates the outlier data; step three, the fault identification module analyzes the corrected current and voltage data and identifies the transformer penetrability fault; step four, a state evaluation module calculates the overvoltage and the crossing current of the transformer, and evaluates and early-warns the state of the transformer; and fifthly, correcting the short circuit model, namely checking and correcting the impedance value of the short circuit model and the maximum short circuit current model which can bear under dynamic and thermal stability according to the penetrating short circuit fault data. In the first step, the sampling rate is dynamically changed along with the waveform history characteristics, outlier data and feedback data of the penetrating fault recognition, and the data acquisition device has three modes of a basic mode, a monitoring mode and a fault recording mode according to different feedback data. Further preferably, the treatment process of the second step