CN-121978447-A - Electric power loop inspection method based on intelligent electric energy meter

CN121978447ACN 121978447 ACN121978447 ACN 121978447ACN-121978447-A

Abstract

The application relates to an electric power loop inspection method based on an intelligent electric energy meter, which comprises the steps of determining working condition grades according to a current load current effective value, determining a first threshold value and a second threshold value from a threshold value mapping relation, obtaining a voltage loop self-monitoring error variation, a current loop self-monitoring error variation and terminal temperature variation of each terminal, executing working condition interference correction on the variation and executing change trend analysis, responding to the condition that at least one of the corrected error variation exceeds the first threshold value and at least one of the corrected terminal temperature variation exceeds the second threshold value, or responding to the change trend analysis, determining that an early degradation terminal exists, determining that a loop abnormality exists, and determining the fault type according to the combination of the corrected double-channel error variation and each terminal temperature variation. According to the application, the self-monitoring error and the terminal temperature are subjected to correlation analysis under the unified load working condition background, so that the accuracy of judging the abnormality of the power circuit under the complex working condition is improved.

Inventors

ZHANG RENFA
YU CHAOLIN
WANG JIALI
ZHOU BO

Assignees

宁波飞羚电气有限公司

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (10)

1. The utility model provides a power loop inspection method based on intelligent ammeter which characterized in that includes: S1, acquiring a current load current effective value, determining a current working condition level according to the ratio of the current load current effective value to rated current, and determining a first threshold value and a second threshold value from a preset threshold value mapping relation according to the current working condition level; S2, acquiring the self-monitoring error variation of the voltage loop and the self-monitoring error variation of the current loop of the metering loop; S3, acquiring terminal temperature variation of each terminal, wherein each terminal comprises a current terminal and a voltage terminal; s4, working condition interference correction is carried out on the voltage loop self-monitoring error variable quantity, the current loop self-monitoring error variable quantity and the terminal temperature variable quantity of each terminal, corrected voltage loop self-monitoring error variable quantity, corrected current loop self-monitoring error variable quantity and corrected terminal temperature variable quantity of each terminal are obtained, and change trend analysis is carried out on the terminal temperature variable quantity of each terminal; S5, determining that a loop abnormality exists in the power loop of the intelligent electric energy meter in response to at least one of the corrected voltage loop self-monitoring error variation and the corrected current loop self-monitoring error variation exceeding the first threshold and at least one of the corrected terminal temperature variation of each terminal exceeding the second threshold, or in response to determining that a terminal in an early degradation state exists in each terminal according to the change trend analysis; S6, in response to determining that the power loop has the loop abnormality, determining the fault type according to the corrected voltage loop self-monitoring error variation, the corrected current loop self-monitoring error variation, the combination of the terminal temperature variation of the current terminal and the terminal temperature variation of the voltage terminal in the terminal temperature variation of each terminal.
2. The power circuit inspection method according to claim 1, wherein S6 comprises the sub-steps of: s61, determining that the fault type is abnormal current terminal contact in response to the corrected current loop self-monitoring error variation exceeding the first threshold and the terminal temperature variation of the current terminals in the corrected terminal temperature variation exceeding the second threshold; S62, determining that the fault type is abnormal contact of the voltage terminals in response to the corrected voltage loop self-monitoring error variation exceeds the first threshold and the terminal temperature variation of the voltage terminals in the corrected terminal temperature variation exceeds the second threshold; s63, determining that the fault type is degradation of a current sampling device in response to the corrected current loop self-monitoring error variation exceeds the first threshold value and the terminal temperature variation of the current terminal in the corrected terminal temperature variation does not exceed the second threshold value; s64, determining that the fault type is degradation of a voltage sampling device in response to the corrected voltage loop self-monitoring error variation exceeds the first threshold and the terminal temperature variation of the voltage terminal in the corrected terminal temperature variation does not exceed the second threshold; S65, determining that the fault type is the reference drift of the metering chip in response to the corrected current loop self-monitoring error variation and the corrected voltage loop self-monitoring error variation both exceeding the first threshold and the corrected terminal temperature variation of each terminal not exceeding the second threshold.
3. The power circuit inspection method according to claim 2, wherein the trend analysis performed on the terminal temperature variation amount of each terminal in S4 includes: s41, calculating the terminal temperature rise rate of each terminal between two adjacent inspection cycles; s42, calculating a terminal temperature difference value between each terminal and the rest of terminals, and determining that the terminal is in an early degradation state in response to the terminal temperature rise rate of one terminal exceeding a third threshold value and the terminal temperature difference value between the terminal and the rest of terminals exceeding a fourth threshold value.
4. A power circuit inspection method according to claim 3, characterized in that S41 comprises the following sub-steps: S411, acquiring a terminal temperature acquisition value of each terminal in a Kth inspection period and a terminal temperature acquisition value of each terminal in a Kth-1 th inspection period, wherein K is a positive integer greater than 1; s412, dividing the difference value between the terminal temperature acquisition value of the Kth inspection period and the terminal temperature acquisition value of the Kth-1 inspection period by the time interval between the two adjacent inspection periods to obtain the terminal temperature rise rate; s413, performing sliding window averaging on N terminal temperature rise rates obtained through calculation of continuous N inspection periods to obtain a smoothed terminal temperature rise rate, and comparing the smoothed terminal temperature rise rate with the third threshold, wherein N is a positive integer greater than or equal to 2.
5. A power loop inspection method according to claim 3, wherein the operating condition disturbance correction in S4 includes at least one of: In response to the change of the current load current effective value in a patrol period exceeding the preset proportion of the rated current, adding a mark for a load transition period to the patrol period, and suspending the judgment that the terminal temperature rise rate exceeds the third threshold value in the load transition period; Before executing the judgment that the terminal temperature difference exceeds the fourth threshold, calculating an average value of the terminal temperature variation amounts of the terminals, subtracting the average value from the terminal temperature variation amounts of the terminals to obtain differential mode temperature variation amounts, and executing the judgment that the fourth threshold is replaced by the differential mode temperature variation amounts; and in response to the fact that the total harmonic distortion rate of the power grid voltage acquired by the intelligent electric energy meter exceeds a harmonic interference threshold, smoothing the self-monitoring error variation of the voltage loop and the self-monitoring error variation of the current loop in a sliding window median mode, and then executing the judgment of the S5.
6. The power circuit inspection method according to claim 5, wherein the determination of the fourth threshold value is performed in accordance with the differential mode temperature variation amount instead of the terminal temperature difference value, comprising the sub-steps of: S71, acquiring a terminal temperature acquisition value of each terminal in each inspection period; S72, calculating a difference value of the terminal temperature acquisition value of each terminal relative to the terminal temperature acquisition value of the previous inspection period to obtain the terminal temperature variation of each terminal; s73, averaging the terminal temperature variation of each terminal to obtain a common mode temperature variation component; S74, subtracting the common mode temperature change component from the terminal temperature change quantity of each terminal to obtain a differential mode temperature change quantity of each terminal; s75, calculating a difference value between the differential mode temperature variation of each terminal and the differential mode temperature variation of the other terminals, and determining that the temperature difference of the terminals is abnormal in response to the difference value exceeding the fourth threshold value.
7. The power circuit inspection method according to claim 5, wherein the adding a flag to the inspection cycle as a load transition further comprises: continuously acquiring terminal temperature acquisition values of all terminals in the load transition period and storing the terminal temperature acquisition values as a transition period temperature sequence; Releasing the mark of the load transition period in response to the variation of the effective value of the current load current in continuous M tour-inspection periods not exceeding the preset proportion of the rated current, wherein M is a positive integer greater than 1; After the mark of the load transition period is released, calculating expected accumulated temperature rise values of all terminals in the load transition period according to the current working condition grade corresponding to all inspection periods in the load transition period, and comparing actual accumulated temperature rise values of all terminals in the transition period temperature sequence with the expected accumulated temperature rise values; In response to the actual accumulated temperature rise value of a terminal exceeding the sum of the expected accumulated temperature rise value and a preset deviation amount, determining that the terminal is present with a superimposed degradation signal during the load transition period, and determining that the terminal with the superimposed degradation signal is in the early degradation state.
8. The method according to claim 5, wherein smoothing the voltage loop self-monitoring error variation and the current loop self-monitoring error variation by using a sliding window to take a median value comprises: Determining a harmonic interference level according to the total harmonic distortion rate of the power grid voltage; selecting the width of the sliding window from a preset window width mapping relation according to the harmonic interference level, wherein the higher the harmonic interference level is, the larger the width of the sliding window is; And in response to the total harmonic distortion rate of the power grid voltage exceeds an extreme interference threshold, marking the self-monitoring error variation of the voltage loop and the self-monitoring error variation of the current loop, which are acquired in a corresponding inspection period, as invalid data, wherein the invalid data are not included in the median calculation of the sliding window.
9. The power circuit inspection method of claim 5, further comprising: determining that the inspection period is in a composite interference state in response to the fact that the mark of the load transition period and the total harmonic distortion rate of the power grid voltage exceed the harmonic interference threshold value simultaneously hold in the same inspection period; Within a preset observation window after the composite interference state is released, respectively reducing the third threshold value and the fourth threshold value to preset proportions of respective nominal values so as to improve the detection sensitivity of the early degradation state which is shielded during the composite interference state; And restoring the third threshold value and the fourth threshold value to respective nominal values in response to a failure to determine that there is a terminal in the early degradation state among the terminals within the preset observation window.
10. The power circuit inspection method according to claim 1, wherein in the threshold mapping relationship, the larger the load current corresponding to the current working condition level is, the larger the second threshold is, and the smaller the first threshold is; the second threshold is determined according to the following modes that according to load current corresponding to the current working condition level and standard contact resistance of each terminal, expected temperature rise values of each terminal under the current working condition level are calculated, and the expected temperature rise values are added with preset allowable deviation values to obtain the second threshold.

Description

Electric power loop inspection method based on intelligent electric energy meter Technical Field The application relates to the field of intelligent electric energy meters, in particular to an electric power loop inspection method based on an intelligent electric energy meter. Background The intelligent electric energy meter plays a core role of electric energy metering in the electric power system. In the long-term operation process, the metering loop of the electric energy meter can be influenced by device aging, environmental change and human factors to cause performance degradation, for example, metering errors are increased due to parameter drift of a sampling device, or contact resistance is increased due to oxidation, looseness and other reasons of a contact surface of a terminal seat, and abnormal heating is generated in a through-flow state. In order to monitor the health of the metering circuit in an operating state, two types of online monitoring means have emerged in the prior art. The method is based on metering error monitoring of self-monitoring signal injection, and is characterized in that an inter-harmonic signal is injected into a sampling loop through a reference source arranged in a metering chip, and the variation of the signal is extracted to judge whether the sampling loop is abnormal or not. The other type is that the temperature of the terminal seat is monitored, the temperature data of each terminal is collected through a temperature sensor, and whether the contact state of the terminal is normal or not is judged. However, the two types of means operate independently in the existing scheme, respectively set respective decision thresholds and respectively trigger respective alarms. This independent operation makes it difficult for existing schemes to distinguish between true loop faults and parameter fluctuations due to non-fault causes. Specifically, when the self-monitoring error is interfered by a dynamic load spectrum during load change, jump is easy to generate, the temperature of a terminal is increased under a large-current normal working condition or when the ambient temperature fluctuates, and the abnormal parameters of the terminal and the ambient temperature do not necessarily mean that a loop fails. Because of the lack of correlation analysis between two types of monitoring results, the abnormal caused by loop faults and the normal fluctuation caused by working condition change cannot be distinguished by judging according to any type of parameters, namely when the load spectrum interference causes self-monitoring error jump, the independent error monitoring cannot eliminate false alarms by means of the normal state of the terminal temperature, and when the terminal temperature rises due to high-current working conditions, the independent temperature monitoring cannot confirm that the temperature rise belongs to a normal range by means of the normal state of the self-monitoring error. The complementary information contained in the two types of monitoring data is not utilized, so that the reliability of a judging result under a complex working condition is insufficient. Disclosure of Invention In order to perform correlation analysis on the self-monitoring error and the terminal temperature under the unified load working condition background, and accurately judge whether the power circuit is abnormal or not, the application provides a power circuit inspection method based on an intelligent electric energy meter. The application provides an electric power loop inspection method based on an intelligent electric energy meter, which adopts the following technical scheme: an electric power loop inspection method based on an intelligent electric energy meter comprises the following steps: S1, acquiring a current load current effective value, determining a current working condition level according to the ratio of the current load current effective value to rated current, and determining a first threshold value and a second threshold value from a preset threshold value mapping relation according to the current working condition level; S2, acquiring the self-monitoring error variation of the voltage loop and the self-monitoring error variation of the current loop of the metering loop; S3, acquiring terminal temperature variation of each terminal, wherein each terminal comprises a current terminal and a voltage terminal; s4, working condition interference correction is carried out on the voltage loop self-monitoring error variable quantity, the current loop self-monitoring error variable quantity and the terminal temperature variable quantity of each terminal, corrected voltage loop self-monitoring error variable quantity, corrected current loop self-monitoring error variable quantity and corrected terminal temperature variable quantity of each terminal are obtained, and change trend analysis is carried out on the terminal temperature variable quantity of each terminal; S5, determi