Partial discharge threshold value self-adaption method and device

Abstract

The invention discloses a partial discharge threshold value adaptive method and device. The method comprises the following steps: acquiring a standard power threshold value; judging whether power-off restart occurs or not, and if so, acquiring first power data acquired in a first preset time period adjacent to the power-off restart moment; calculating a first power value according to the first power data; judging whether the first power value is within the change range of the standard power threshold, and if not, acquiring historical power data; calculating a historical power value according to the historical power data; and judging whether the first electric power value is within the change range of the historical electric power value, and if not, taking the first electric power value as the standard electric power threshold value. When the power equipment changes, the discharge threshold value is automatically adjusted according to the environment change, the adaptability is high, a laboratory environment and an additional partial discharge simulation device are not needed, and the cost is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power early warning, and in particular to a partial discharge threshold adaptive method and device. Background Art

[0002] During long-term use, power equipment and power cables may cause partial discharge due to insulation degradation or damage. Therefore, if it is not discovered and resolved in time, it will cause significant economic losses or even casualties.

[0003] Existing partial discharge monitoring equipment detects partial discharge signals and analyzes partial discharge status through ultra-high frequency, ultrasonic waves, geomagnetic waves and other principles. Regardless of the principle, it is necessary to analyze the basic characteristics of the partial discharge signal, such as peak value, mean value, pulse number, etc. Because the on-site RF environment in actual application scenarios is very complex, various interference signals and partial discharge signals overlap. Therefore, a threshold is set when using partial discharge monitoring equipment. For example, when the signal peak is greater than a certain threshold, it is considered that there is a partial discharge signal, otherwise it is considered that there is only an interference signal. Therefore, the value of the threshold determines the accuracy of monitoring.

[0004] At present, the existing technology proposes: by building an experimental environment, using a large-scale partial discharge simulation device to send out a simulated partial discharge signal, and then using the partial discharge monitoring equipment to collect it, and obtaining the threshold value through certain calculation and analysis. This method can be completed before leaving the factory, and the after-sales user does not need to operate it directly, which is very simple. However, the cost is very high, and the simulated partial discharge signal cannot fully consider and simulate the impact of various interference signals on the scene, so the judgment of the threshold value is not very accurate.

[0005] Some other technical solutions propose: in the actual field environment, first install the partial discharge monitoring equipment, then use a portable partial discharge simulation device to send out a simulated partial discharge signal, which is collected by the partial discharge monitoring equipment, and the threshold is obtained after a certain calculation and analysis. This method is often completed by the manufacturer before formal delivery, and the after-sales user does not need to operate it directly, which is very simple; and the influence of various interference signals on site is taken into account, so the accuracy of the threshold judgment is improved. However, power equipment usually has a safety distance requirement, and the simulated partial discharge signal is not directly applied to the power equipment, which is different from the real partial discharge signal. If the simulated partial discharge signal is to be applied directly to the power equipment, it must be shut down first, which is inconvenient to operate.

[0006] Some other technical solutions propose: based on the professional knowledge of professionals combined with various existing experiences, the threshold is obtained by analyzing the actual project situation. Although this method is low-cost, it is very dependent on professional knowledge and experience, and it is difficult to analyze the entire situation of the actual project, and the judgment accuracy is very low. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a partial discharge threshold self-adaptation method and device to improve the accuracy of threshold judgment.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A partial discharge threshold adaptive method, comprising:

[0010] Get the standard power threshold;

[0011] Determine whether a power-off restart occurs, and if so, obtain first power data collected within a first preset time period adjacent to the power-off restart moment;

[0012] Calculate a first power value according to the first power data;

[0013] determining whether the first power value is within a variation range of the standard power threshold, and if not, acquiring historical power data;

[0014] Calculate the historical power value according to the historical power data;

[0015] It is determined whether the first power value is within the variation range of the historical power value; if not, the first power value is used as the standard power threshold.

[0016] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0017] A partial discharge threshold self-adaptation device comprises a storage module, a processing unit and a computer program stored in the storage module and executable on the processing unit. When the processing unit executes the computer program, each step in the partial discharge threshold self-adaptation method as described above is implemented.

[0018] The beneficial effects of the present invention are as follows: by acquiring power data of a corresponding time period after a power outage and restart of the device, and calculating a first power value based on the power data and then comparing it with a standard power threshold, it is determined whether it exceeds the range of the standard power threshold; if it exceeds the range of the standard power threshold, it is further determined whether it exceeds the range of variation of historical power values; if it exceeds the range of variation of historical power values, the first power value is used as the standard power threshold to achieve automatic adjustment of the discharge threshold, and when the power equipment changes, the discharge threshold is automatically adjusted according to environmental changes, the present invention has strong adaptability, does not require a laboratory environment and additional partial discharge simulation equipment, etc., and greatly reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A flowchart of a partial discharge threshold adaptive method according to an embodiment of the present invention;

[0020] Figure 2 is another step flow chart of a partial discharge threshold adaptive method in an embodiment of the present invention;

[0021] Figure 3 It is a structural schematic diagram of a partial discharge threshold adaptive device in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0023] The existing technical solutions usually set the threshold in advance before the partial discharge monitoring equipment is officially delivered and put into operation. However, the power equipment at the project site is not static. For example, expansion and renovation, such as old replacement and renovation, etc., will cause changes in the actual situation. Such pre-set thresholds are often difficult to reduce costs and achieve good results. In response to the above technical problems, the present invention provides a partial discharge threshold adaptive method and device, which are as follows:

[0024] Please refer to Figure 1 , a partial discharge threshold adaptive method, comprising:

[0025] Get the standard power threshold;

[0026] Determine whether a power-off restart occurs, and if so, obtain first power data collected within a first preset time period adjacent to the power-off restart moment;

[0027] Calculate a first power value according to the first power data;

[0028] determining whether the first power value is within a variation range of the standard power threshold, and if not, acquiring historical power data;

[0029] Calculate the historical power value according to the historical power data;

[0030] It is determined whether the first power value is within the variation range of the historical power value; if not, the first power value is used as the standard power threshold.

[0031] From the above description, it can be seen that the beneficial effects of the present invention are: by obtaining power data of the corresponding time period after the equipment is powered off and restarted, and calculating the first power value based on the power data and then comparing it with the standard power threshold, it is determined whether it exceeds the range of the standard power threshold. When it exceeds the range of the standard power threshold, it is further determined whether it exceeds the range of changes in historical power values. When it exceeds the range of changes in historical power values, the first power value is used as the standard power threshold to achieve automatic adjustment of the discharge threshold. When the power equipment changes, the discharge threshold is automatically adjusted according to environmental changes. It has strong adaptability and does not require a laboratory environment and additional partial discharge simulation equipment, etc., which greatly reduces costs.

[0032] Furthermore, the obtaining of the standard power threshold comprises:

[0033] Determine whether the standard power threshold is stored in the storage module, and if not, obtain the second power data collected within a second preset time period;

[0034] The standard power threshold is calculated according to the second power data.

[0035] From the above description, it can be seen that when no standard power threshold is set in the device, the corresponding standard power threshold can be generated by collecting power data. For example, when there is no threshold when the device is powered on for the first time, the corresponding standard power threshold can be automatically generated after the device has been running for a period of time.

[0036] Furthermore, the first preset time period and the second preset time period have the same length.

[0037] From the above description, it can be seen that by setting the first preset time period and the second preset time period to the same time length, that is, the standard power threshold and the first power value are data generated based on the same time length, and are compared based on the same time length, the change in power value under the same time length can be reflected.

[0038] Further, the calculating the standard power threshold according to the second power data includes:

[0039] Calculating the average value of the second power data within the second preset time period;

[0040] The standard power threshold is obtained by multiplying the mean value by a preset coefficient.

[0041] It can be seen from the above description that by calculating the mean of the power data and then multiplying it by the preset coefficient, the reliability of setting the discharge threshold can be improved, and frequent false alarms caused by a low discharge threshold can be avoided.

[0042] Furthermore, before obtaining the standard power threshold, the method further includes:

[0043] Determine whether the preset operation cycle is reached, and if so, execute the step of obtaining the standard power threshold.

[0044] From the above description, it can be seen that by periodically updating the standard power threshold, the device can periodically determine whether the on-site environment has changed, and automatically update the discharge threshold when there is a significant change in the on-site environment to adapt to the changing on-site environment.

[0045] Furthermore, the obtaining of the standard power threshold comprises:

[0046] The third power data collected in the previous operation cycle is acquired, and the standard power threshold is calculated according to the third power data.

[0047] It can be seen from the above description that when the next operation cycle is reached, the standard power threshold is generated by acquiring the power data collected in the previous operation cycle, so that the standard power threshold can change in time with the operation cycle.

[0048] Further, the determining whether the first power value is within the variation range of the standard power threshold value includes:

[0049] Calculating a difference between the first power value and the standard power value, and dividing the difference by the standard power threshold to obtain a first comparison value;

[0050] A first comparison threshold is obtained, and it is determined whether the first comparison value is greater than the first comparison threshold. If so, the first power value is not within the variation range of the standard power threshold.

[0051] From the above description, it can be seen that by calculating the difference between the first power value and the standard power value and then performing ratio calculation, the degree of change of the first power value relative to the standard power value can be effectively reflected, thereby accurately determining whether the discharge threshold needs to be updated.

[0052] Furthermore, the acquiring of historical power data includes:

[0053] Acquiring power data collected within a third preset time period as the historical power data;

[0054] The duration of the third preset time period is longer than the duration of the first preset time period.

[0055] From the above description, it can be seen that the duration of the third preset time period is greater than the duration of the first preset time period, that is, the historical power data is based on data acquired over a longer time period. Therefore, by comparing the first power value with the historical power value, it is possible to reflect the changes in the first power value over a longer time period, thereby accurately determining whether the discharge threshold needs to be updated.

[0056] Further, the determining whether the first power value is within the variation range of the historical power value includes:

[0057] Calculating a difference between the first power value and the historical power value, and dividing the difference by the first power value to obtain a second comparison value;

[0058] A second comparison threshold is obtained, and it is determined whether the second comparison value is greater than the second comparison threshold. If so, the first power value is not within the variation range of the historical power value.

[0059] From the above description, it can be seen that by calculating the difference between the first power value and the historical power value and then performing ratio calculation, the degree of change of the first power value relative to the historical power value can be effectively reflected, thereby accurately determining whether the discharge threshold needs to be updated.

[0060] Another embodiment of the present invention provides a partial discharge threshold self-adaptation device, comprising a storage module, a processing unit, and a computer program stored in the storage module and executable on the processing unit. When the processing unit executes the computer program, each step in the partial discharge threshold self-adaptation method described above is implemented.

[0061] The partial discharge threshold adaptive method and device provided by the present invention can be applied to power detection scenarios, and are described below through specific implementation methods:

[0062] Embodiment 1

[0063] Please refer to Figure 1 , a partial discharge threshold adaptive method, comprising:

[0064] S1. Obtain the standard power threshold; specifically: determine whether the standard power threshold is stored in the storage module, if not, obtain the second power data collected in the second preset time period; calculate the standard power threshold based on the second power data; for example, if the second preset time period is one day, obtain the power data completed on the first day after the device is officially delivered for use to calculate the standard power threshold; or when the device is powered on for the first time and there is no threshold, operate according to the default threshold of 6dB. At the same time, during the operation of the device, the radio frequency signal is periodically detected and recorded as Vre. When the peak value of the radio frequency signal Vre is detected to exceed the discharge threshold V, it is considered that there is a local discharge signal, otherwise it is considered to be an interference signal.

[0065] The specific calculation method of the standard power threshold is as follows: after calculating the average of the second power data in the second preset time period, multiply the average by a preset coefficient to obtain the standard power threshold; for example, 6 times the average of the signal on the first day is taken as V1, which is used as the local discharge judgment threshold V (i.e., the standard power threshold) and stored in the storage module; wherein the preset coefficient can be set according to the historical discharge records of the area, for example, set to 6 times, 7 times, etc.

[0066] S2. Determine whether a power outage and restart occurs. If so, obtain the first power data collected within the first preset time period adjacent to the power outage and restart moment. In one optional implementation, the first preset time period is set to be the same length as the second preset time period, that is, the first preset time period and the second preset time period are both one day. Then, after the power outage and restart, collect the power data of the day; or collect the power data of 12 hours before and after the power outage and restart, or collect the power data of 24 hours before the power outage and restart. The time period can be selected according to actual needs. The power outage and restart specifically include the following situations: ① Simple power outage and restart; ② Maintenance power outage and restart after an abnormality occurs; ③ Power outage and restart due to changes in the monitored equipment (expansion or reduction of the equipment to be detected; and placing the equipment of this scheme in other places to be detected, which can be regarded as a power outage and restart).

[0067] S3. Calculate a first power value based on the first power data; use the same calculation method as that for calculating the standard power threshold to obtain the first power value, that is, calculate 6 times the signal average value for one day and record it as V2.

[0068] S4. Determine whether the first power value is within the variation range of the standard power threshold. If not, obtain historical power data. Specifically:

[0069] S41, calculating the difference between the first power value and the standard power value, and dividing the difference by the standard power threshold to obtain a first comparison value P, that is:

[0070]

[0071] S42, obtain the first comparison threshold, determine whether the first comparison value is greater than the first comparison threshold, if so, the first power value is not within the variation range of the standard power threshold; for example, in this embodiment, the first comparison threshold is 20%, that is, when P≤20%, it is considered that the environment has not changed much, and the previous judgment threshold V1 continues to be used as the discharge threshold; when P>20%, it is considered that there are certain changes in the environment, and further judgment is required, that is, execute step S5. For example, in case ①, the threshold will not fluctuate greatly, so there is no need to overwrite and replace the latest threshold range; and cases ② and ③ both involve certain changes, so the latest cycle data and historical data collected again will be compared; historical data are multiple gradients, and the accuracy is gradually improved. For example, in this embodiment, they are set to 1 day and 10 days respectively for comparison, and then decide whether to replace the new threshold range after comparison.

[0072] S5. Calculate the historical power value based on the historical power data, specifically: obtain the power data collected within the third preset time period as the historical power data; the duration of the third preset time period is greater than the duration of the first preset time period. For example, if the third preset time period is set to 10 days, the historical power data of the 10 days before the power outage and restart is obtained to calculate the historical power value; wherein, the calculation method of the historical power value is the same as the calculation method of the standard power value, recorded as V3; that is, V3 is obtained by finding the average value of the previous ten days, and reading "V1" of each historical day; wherein each day needs to be calculated by a certain coefficient (6 times), and each data of the previous ten days is multiplied by the coefficient, so there is no need to multiply the coefficient when calculating the average value; at the same time, the historical data of the 10 days before the power outage and restart is preset, but the data of the previous 10 days may be 0, and the corresponding situation is: not enough data storage was collected before the power outage and restart.

[0073] S6. Determine whether the first power value is within the variation range of the historical power value. If not, use the first power value as the standard power threshold. The specific determination method is as follows:

[0074] S61, calculating the difference between the first power value and the historical power value, and dividing the difference by the first power value to obtain a second comparison value P3, that is:

[0075]

[0076] S62, obtain a second comparison threshold, determine whether the second comparison value is greater than the second comparison threshold, if so, the first power value is not within the variation range of the historical power value; for example, in this embodiment, the second comparison threshold is 20%, that is, when P≤20%, it is considered that the environment has not changed much, and continue to use the previous judgment threshold V1 as the discharge threshold; when P>20%, it is considered that the environment has changed significantly, and V2 is used as the discharge threshold, which is stored in the storage module, and an alarm is issued to remind the technicians to change the discharge threshold, which is helpful for analyzing the on-site situation.

[0077] Among them, in an optional implementation, the discharge threshold is also updated through the operation cycle, specifically: determine whether the preset operation cycle is reached, and if so, execute the step of obtaining the standard power threshold; wherein, when obtaining the standard power threshold, the third power data collected in the previous operation cycle is obtained, and the standard power threshold is calculated according to the third power data; for example, the operation cycle is one day, and 6 o'clock is used as the start of the day, then when the device runs to 6 o'clock every day, it starts to calculate 6 times the signal mean of the previous day, recorded as v, stored in the historical data, and used as the initial discharge threshold of the day.

[0078] Please refer to Figure 2 , which is an implementation step of an optional implementation mode of this embodiment, including steps A1-A15;

[0079] A1. Obtain the discharge threshold V stored in the storage module, and determine whether the discharge V is equal to 0. If so, execute step A2; if not, execute step A6; that is, execute the above step of obtaining the standard power threshold.

[0080] A2. Collect and record data for one day, and then execute step A3; that is, execute the step of acquiring the second power data collected within the second preset time period in the above step S1.

[0081] A3, calculate the marked power threshold V1, and then execute step A4; that is, execute the step of calculating the standard power threshold in the above step S1.

[0082] A4. Let V=V1, and then execute step A5; that is, use the above calculation result as the discharge threshold.

[0083] A5. Periodically detect the radio frequency signal Vre, and then execute step A14.

[0084] A6, determine whether a power-off restart occurs, if not, execute step A5, if yes, execute step A7; that is, execute the step of determining whether a power-off restart occurs in step S2.

[0085] A7, collect and record data for one day, and then execute step A8; that is, execute the step of acquiring the first power data collected within the first preset time period adjacent to the power off and restart moment in step S2.

[0086] A8. Calculate the first power value V2 and the first comparison value P, and then execute step A9; that is, execute the above step S3.

[0087] A9. Determine whether the first comparison value P is less than or equal to 20%. If so, execute step A5; otherwise, execute step A10; that is, execute step S4.

[0088] A10, obtain the historical data of the previous 10 days, and then execute step A11; that is, execute the step of obtaining historical power data in step S4.

[0089] A11. Calculate the second power value V3 and the second comparison value P3, and then execute step A12; that is, execute step S5.

[0090] A12. Determine whether the second comparison value P3 is less than or equal to 20%. If so, execute step A5; otherwise, execute step A13; that is, execute step S6.

[0091] A13, set V=V2 and give an alarm, then execute step A5; that is, use the first power value as the discharge threshold. The calculated p3 is greater than 20%, which proves that the average value fluctuates greatly. The data of the previous ten days may not be in the same environment as the measurement V2; for example, there are two devices before the power outage and restart, and the number increases to 5 devices after the power outage. The data after the restart will change significantly; in this case, the reference value of historical data is not great, so V2 (the most recently measured true value) is forcibly assigned as the closest average value. At the same time as the assignment, an alarm should be issued to notify the staff of the detected environmental changes.

[0092] A14, determine whether Vre is greater than V, if so, execute step A15, if not, execute step A5;

[0093] A15, alarm, where the alarm method includes but is not limited to alarm lights, buzzers, alarm data upload to the server, etc., and then execute step A5. The alarm in step A15 is different from the alarm in step A13. The alarm here "V=V2 and alarm" mainly reflects the meaning of notification information, and can be processed after running for a period of time; for example, if the P of V2 is less than 20% in the next cycle, it means that the monitoring is on track, and the previous "V=V2 and alarm" does not need to be processed and the equipment can operate normally; while the periodic monitoring alarm is to detect and judge the risk of local discharge, and it is necessary to require the staff to repair it in time.

[0094] Embodiment 2

[0095] Please refer to Figure 3, a local discharge threshold self-adaptation device, comprising a storage module, a processing unit and a computer program stored in the storage module and executable on the processing unit, wherein the processing unit implements the various steps in a local discharge threshold self-adaptation method as described in the first embodiment when executing the computer program. The device further comprises a clock module and an acquisition module, wherein the storage module is used to store data for reading and writing by the processing unit; the clock module provides date and time; the acquisition module realizes the acquisition of radio frequency signals; the processing unit controls the operation of other modules, for example, the processing unit simultaneously obtains the current acquisition value from the acquisition module and the current date and time from the clock module, and stores them together in the storage module as historical data; and when the operation cycle is one day, and 6 o'clock is taken as the start of the day, when the device runs to 6 o'clock every day, it starts to calculate 6 times the signal mean of the previous day, recorded as v, and stores it in the historical data.

[0096] In summary, the present invention provides a partial discharge threshold adaptive method and device, which obtains power data of a corresponding time period after the equipment is powered off and restarted, calculates a first power value based on the power data, and then compares it with the standard power threshold to determine whether it exceeds the range of the standard power threshold. When it exceeds the range of the standard power threshold, it further determines whether it exceeds the range of changes in historical power values. When it exceeds the range of changes in historical power values, the first power value is used as the standard power threshold to achieve automatic adjustment of the discharge threshold. When the power equipment changes, the discharge threshold is automatically adjusted according to environmental changes. It has strong adaptability and does not require a laboratory environment or additional partial discharge simulation equipment, which greatly reduces costs.

[0097] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A partial discharge threshold adaptive method, characterized in that: include: Get the standard power threshold; Determine whether a power-off restart occurs, and if so, obtain first power data collected within a first preset time period adjacent to the power-off restart moment; Calculate a first power value according to the first power data; determining whether the first power value is within a variation range of the standard power threshold, and if not, acquiring historical power data; Calculate the historical power value according to the historical power data; It is determined whether the first power value is within the variation range of the historical power value; if not, the first power value is used as the standard power threshold.

2. A partial discharge threshold adaptive method according to claim 1, characterized in that: The acquisition of the standard power threshold comprises: Determine whether the standard power threshold is stored in the storage module, and if not, obtain the second power data collected within a second preset time period; The standard power threshold is calculated according to the second power data.

3. A partial discharge threshold adaptive method according to claim 2, characterized in that: The first preset time period and the second preset time period have the same length.

4. A partial discharge threshold adaptive method according to claim 2, characterized in that: The calculating the standard power threshold according to the second power data comprises: Calculating the average value of the second power data within the second preset time period; The standard power threshold is obtained by multiplying the mean value by a preset coefficient.

5. A partial discharge threshold adaptive method according to claim 1, characterized in that: Before obtaining the standard power threshold, the method further includes: Determine whether the preset operation cycle is reached, and if so, execute the step of obtaining the standard power threshold.

6. A partial discharge threshold adaptive method according to claim 5, characterized in that: The acquisition of the standard power threshold comprises: The third power data collected in the previous operation cycle is acquired, and the standard power threshold is calculated according to the third power data.

7. A partial discharge threshold adaptive method according to claim 1, characterized in that: The determining whether the first power value is within the variation range of the standard power threshold value includes: Calculating a difference between the first power value and the standard power value, and dividing the difference by the standard power threshold to obtain a first comparison value; A first comparison threshold is obtained, and it is determined whether the first comparison value is greater than the first comparison threshold. If so, the first power value is not within the variation range of the standard power threshold.

8. A partial discharge threshold adaptive method according to claim 1, characterized in that: The acquisition of historical power data includes: Acquiring power data collected within a third preset time period as the historical power data; The duration of the third preset time period is longer than the duration of the first preset time period.

9. A partial discharge threshold adaptive method according to claim 8, characterized in that: The determining whether the first power value is within the variation range of the historical power value includes: Calculating a difference between the first power value and the historical power value, and dividing the difference by the first power value to obtain a second comparison value; A second comparison threshold is obtained, and it is determined whether the second comparison value is greater than the second comparison threshold. If so, the first power value is not within the variation range of the historical power value.

10. A partial discharge threshold adaptive device, comprising a storage module, a processing unit and a computer program stored in the storage module and executable on the processing unit, characterized in that: When the processing unit executes the computer program, each step of the partial discharge threshold adaptive method according to any one of claims 1 to 9 is implemented.

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