A harmonic elimination device with self-monitoring function and a monitoring method

Abstract

The application discloses a kind of harmonic elimination device with self-monitoring function and monitoring method, it is related to harmonic elimination device technical field, it includes two relevant parallel zinc oxide resistance, temperature acquisition module and controller, each zinc oxide resistance branch is in series with disconnecting switch, the controller can control the closing and opening of disconnecting switch, the temperature acquisition module is used to collect the temperature information of zinc oxide resistance, the output end of zinc oxide resistance is arranged to ground, and current transformer is arranged on the ground line of zinc oxide resistance.The application has the effect of facilitating the performance degradation of harmonic elimination resistance monitoring.

Description

Technical Field

[0001] This application relates to the field of harmonic elimination devices, and in particular to a harmonic elimination device and monitoring method with self-monitoring function. Background Technology

[0002] Voltage transformers are key devices in power systems used for voltage measurement, protection, and automatic control. Their core functions are voltage transformation, electrical isolation, and signal transmission, providing safe and accurate voltage signals for measurement, protection, and control equipment. Voltage transformers are commonly installed on the outgoing line side of transformers and the high-voltage busbar side of substations.

[0003] During operation, voltage transformers can experience ferroresonance due to single-phase grounding faults, lightning overvoltages, and line switching. This ferroresonance can increase the likelihood of capacitor bank burnout and transformer damage. To mitigate the impact of ferroresonance on electrical equipment, a harmonic suppression resistor (usually a zinc oxide resistor) is installed on the grounding line of the voltage transformer's neutral point. When ferroresonance occurs, the voltage on the voltage transformer's grounding line rises rapidly, causing the resistance of the suppression resistor to change from a high-resistance state to a low-resistance state. After consuming part of the resonant current, the remaining resonant current is connected to the ground through the grounding line, thus suppressing the ferroresonance phenomenon.

[0004] After the harmonic suppression resistor is put into use, as the number of times the ferroresonant phenomenon is suppressed increases, continuous overvoltage will accelerate the destruction of the grain boundary layer of the resistor inside the harmonic suppression resistor, leading to the performance degradation of the harmonic suppression resistor. Once the harmonic suppression performance of the harmonic suppression resistor is severely degraded, it will be difficult to effectively suppress the overvoltage fault caused by the ferroresonant phenomenon, increasing the risk of damage to electrical equipment. Summary of the Invention

[0005] To facilitate monitoring the performance degradation of the harmonic suppression resistor, this application provides a harmonic suppression device and monitoring method with self-monitoring function.

[0006] Firstly, this application provides a harmonic elimination device with self-monitoring function.

[0007] This application provides a harmonic elimination device with self-monitoring function, which adopts the following technical solution:

[0008] A harmonic suppression device with self-monitoring function includes two related parallel zinc oxide resistors, a temperature acquisition module, and a controller. Each branch of the zinc oxide resistor is connected in series with a disconnect switch. The temperature acquisition module is used to collect the temperature information of the zinc oxide resistor. The controller can control the closing and opening of the disconnect switch and analyze the temperature information collected by the temperature acquisition module. The output terminal of the zinc oxide resistor is grounded, and a current transformer is installed on the grounding line of the zinc oxide resistor.

[0009] The operation process and principle of this device are described in detail in the specific implementation method.

[0010] Secondly, based on the aforementioned harmonic elimination device with self-monitoring function, this application also provides a monitoring method for the harmonic elimination device.

[0011] A method for monitoring a harmonic suppression device includes the following processing steps:

[0012] After switching any zinc oxide resistor, obtain the temperature fluctuation information of the zinc oxide resistor, the preset initial temperature value, and the termination temperature value;

[0013] Based on temperature fluctuation information, a temperature fluctuation curve is generated with time as the horizontal axis and temperature value as the vertical axis.

[0014] In the cooling curve of the temperature fluctuation curve, match the initial time corresponding to the initial temperature value and the termination time corresponding to the termination temperature value.

[0015] The actual temperature decay time of the generated zinc oxide resistor is determined based on the initial and final times.

[0016] Obtain the switching cycles and theoretical temperature decay table for the zinc oxide resistor;

[0017] Match the theoretical temperature decay duration corresponding to the number of switching operations in the theoretical temperature decay table;

[0018] If the actual temperature decay time exceeds the theoretical temperature decay time, an alarm message will be generated.

[0019] Through the above technical solution, after any zinc oxide resistor in this device is switched on and participates in the suppression of ferromagnetic resonance, the temperature fluctuation information, preset initial temperature value, and termination temperature value of this zinc oxide resistor are acquired by the temperature acquisition module (which can be a temperature sensor, such as an infrared thermometer). The temperature fluctuation information refers to the information on the temperature fluctuation of the zinc oxide resistor after it participates in suppressing ferromagnetic resonance; this information reflects the change of the zinc oxide resistor over time. The preset initial temperature value and termination temperature value are explained as follows: the subsequent actual temperature decay time is the time elapsed from the initial temperature value to the termination temperature value after the zinc oxide resistor has finished heating.

[0020] Next, using time as the horizontal curve and temperature as the vertical axis, the temperature fluctuation of the zinc oxide resistor reflected by the temperature fluctuation information is displayed in a two-dimensional coordinate system, thus forming a temperature fluctuation curve. This curve can reflect only the temperature fluctuation of the zinc oxide resistor from the initial temperature value to the final temperature value, or it can reflect the temperature fluctuation of the zinc oxide resistor throughout the entire heating and cooling process.

[0021] In the cooling curve of the temperature fluctuation curve, the initial time corresponding to the initial temperature value and the termination time corresponding to the termination temperature value are matched. Then, the initial time is subtracted from the termination time to obtain the length of time that the zinc oxide resistor takes to cool down from the initial temperature value to the termination temperature value, which is the actual temperature decay time of this zinc oxide resistor.

[0022] Obtain the switching count and theoretical temperature decay table for the zinc oxide resistor. The switching count refers to the number of times the zinc oxide resistor participates in ferromagnetic resonance suppression, i.e., how many times it participates in ferromagnetic resonance suppression. The theoretical temperature decay table is a table comparing the temperature decay data obtained from experiments with the zinc oxide resistor used in this device with the number of switching counts. From this theoretical temperature decay table, the following data can be obtained, for example, after the xth switching of the zinc oxide resistor of this specification, it takes y minutes for the temperature to decay from the initial temperature value to the final temperature value.

[0023] By matching the theoretical temperature decay time corresponding to the number of switching cycles in the theoretical temperature decay table, the theoretical temperature decay time of the zinc oxide resistor in this switching cycle can be obtained. Then, the actual temperature decay time is compared with the theoretical temperature decay time. If the actual temperature decay time is longer than the theoretical temperature decay time, it indicates that the zinc oxide resistor has malfunctioned, and an alarm message is generated to remind the staff to inspect or replace it.

[0024] In a preferred embodiment, this application can be further configured such that, if the actual temperature decay time exceeds the theoretical temperature decay time, the following processing steps are included:

[0025] Obtain the control temperature decay time of another zinc oxide resistor corresponding to the number of cutting cycles;

[0026] If the difference between the measured temperature decay time and the actual temperature decay time is greater than the preset temperature decay time error, an alarm message will be generated.

[0027] By comparing the actual temperature decay time of the zinc oxide resistor being switched with the theoretical temperature decay time using the above technical solution, the actual temperature decay time can also be compared with the control temperature decay time of another zinc oxide resistor in the same device at the same number of switching cycles (the actual temperature decay time and the control temperature decay time refer to the temperature decay time of the zinc oxide resistor being switched and the temperature decay time of another zinc oxide resistor at the same number of switching cycles, respectively, and are distinguished by naming). The reason why the two zinc oxide resistors in the same device can be compared at the same number of switching cycles is that the environmental conditions such as temperature and humidity of the two zinc oxide resistors are the same, but they can be different from the test conditions. After verifying with the experimental data, it can also be verified with the data of another zinc oxide resistor, thereby improving the accuracy of the zinc oxide resistor anomaly judgment.

[0028] If the difference between the measured temperature decay time and the actual temperature decay time is greater than the preset temperature decay time error, it indicates that the zinc oxide resistor is very likely to have a performance abnormality. An alarm message will be generated to alert the staff to inspect or even replace the zinc oxide resistor.

[0029] In a preferred embodiment, this application can be further configured such that, after obtaining another zinc oxide resistor following the reference temperature decay time corresponding to the number of cutting cycles, the following processing steps are included:

[0030] If the other zinc oxide resistor does not have the stated number of switching cycles, then obtain the switching temperature decay rate of the zinc oxide resistor, the current number of switching cycles of the other zinc oxide resistor, and the reference temperature decay time of the other zinc oxide resistor at the current number of switching cycles;

[0031] Based on the reference temperature decay time, number of switching, current number of switching, and switching temperature decay rate, calculate the estimated temperature decay time for another zinc oxide resistor to reach the number of switching cycles;

[0032] If the actual temperature decay time of the zinc oxide resistor reaches the estimated temperature decay time of another zinc oxide resistor, an alarm message will be generated.

[0033] Through the above technical solution, due to certain special reasons, the number of times the two zinc oxide resistors in this device are switched may differ. Therefore, it is possible that the cumulative number of times the zinc oxide resistor is switched this time exceeds the cumulative number of times the other zinc oxide resistor is switched, making it difficult to determine whether the zinc oxide resistor after this switch is abnormal based on the reference temperature decay time of the other set of zinc oxide resistors.

[0034] At this point, the switching temperature decay rate of the zinc oxide resistor, the current switching count of the other zinc oxide resistor, and the reference temperature decay time of the other zinc oxide resistor at the current switching count are obtained. Based on this, the estimated temperature decay time of the other set of zinc oxide resistors when the switching count is reached is calculated. If the actual temperature decay time of the zinc oxide resistor reaches the estimated temperature decay time of the other zinc oxide resistor, it indicates that the zinc oxide resistor is very likely to have abnormal performance degradation, and an alarm message is generated to remind the staff to carry out inspection or replacement.

[0035] In a preferred embodiment, this application can be further configured such that the estimated temperature decay time is calculated using the following formula:

[0036] ;

[0037] This is another zinc oxide resistor's estimated temperature decay time after a number of switching cycles. This is the reference temperature decay time for another zinc oxide resistor at the current switching cycle. It refers to the number of switching operations for the zinc oxide resistor. This is the current switching count of another zinc oxide resistor. It is the rate of temperature decay during switching.

[0038] Through the above technical solutions The difference between the number of switching operations of the two zinc oxide resistors is multiplied by the switching decay rate of the zinc oxide resistor (i.e., the time it takes for the temperature to decay after each switching operation). This gives the temperature decay time when the other zinc oxide resistor reaches the number of switching operations, which is the estimated decay time.

[0039] In a preferred embodiment, this application can be further configured such that the calculation of the switching temperature decay rate includes the following processing steps:

[0040] Obtain the preset sampling period;

[0041] According to the sampling cycle, obtain the first temperature decay time after the first switch in each sampling cycle and the last temperature decay time after the last switch in each sampling cycle.

[0042] The periodic temperature decay duration for each sampling cycle is calculated based on the first and last temperature decay durations for each sampling cycle.

[0043] Based on the periodic temperature decay duration and sampling period of the zinc oxide resistor, the switching temperature decay rate within the sampling period is calculated.

[0044] Based on the first and last number of cuts in each sampling period, the cut span range for each sampling period is set.

[0045] Establish a mapping relationship between the switching span interval and the corresponding switching temperature decay rate;

[0046] Based on the current switching count of another set of zinc oxide resistors, the switching span range to which the current switching count belongs is matched, and the switching temperature decay rate of the matched switching span range is obtained.

[0047] Using the above technical solution, the temperature decay rate during switching is calculated. First, a preset sampling period is obtained. The sampling period can be understood as follows: the temperature decay rate is recalculated every certain number of switching cycles. For example, if the switching cycle is five, then the result from the first switching to the completion of the fifth switching is one sampling cycle.

[0048] Next, obtain the first temperature decay duration after the first switch and the last temperature decay duration after the last switch in each sampling period. For example, in the first sampling period, the switching period is five, and the first switch is the first switch. Then, the duration of temperature decay of the zinc oxide resistor after the first switch is the first temperature decay duration. Similarly, in the first period, the last switch is the fifth switch. After the fifth switch, the duration of temperature decay of the zinc oxide resistor is the last temperature decay duration. Then, the last decay duration minus the first temperature decay duration is the periodic decay duration in this sampling period. And so on, calculate the periodic decay duration in each sampling period.

[0049] Based on the periodic temperature decay duration and sampling period of the zinc oxide resistor, the switching temperature decay rate within the sampling period can be calculated. This can be understood as dividing the periodic temperature decay duration by the sampling period to reflect the temperature decay duration of each switching of the zinc oxide resistor within this sampling period.

[0050] Then, based on the first and last cut counts of each sampling period, the cut span range for each sampling period is set. For example, if the sampling period is five, then the first cut count is one and the last cut count is five, so the cut span range for this sampling period is [1,5]. Similarly, the cut span range for the next sampling period is [6,10].

[0051] Then, establish a mapping relationship between the switching span interval and the corresponding switching temperature decay rate, that is, associate the switching span interval with the corresponding switching temperature decay rate to facilitate subsequent data matching and positioning.

[0052] At this point, based on the current switching count of another set of zinc oxide resistors, the switching span interval to which the current switching count belongs is matched, that is, the switching span interval containing the current switching count is matched, and then the switching temperature decay rate of the matched switching span interval is obtained, so that the estimated temperature decay time can be calculated.

[0053] In a preferred embodiment, this application can be further configured such that the periodic temperature decay duration is calculated using the following formula:

[0054] ;

[0055] It is the duration of periodic temperature decay. It is the duration of the last temperature decay in the sampling period. It is the duration of the first temperature decay in the sampling period. It is the sampling period. It is the number of times the zinc oxide resistor is switched on and off in each sampling cycle.

[0056] Using the above technical solution, the above formula is to subtract the first temperature decay time after the first switch in the sampling period from the last temperature decay time after the last switch in the sampling period.

[0057] In a preferred embodiment, this application can be further configured such that the switching temperature decay rate is calculated using the following formula:

[0058] ;

[0059] It is the temperature decay rate during the sampling cycle. It is the duration of periodic temperature decay. It is the sampling period.

[0060] Using the above technical solution and the above formula, namely the ratio of the periodic temperature decay time to the sampling period, the switching temperature decay rate of the sampling period can be obtained.

[0061] In summary, this application includes the following beneficial technical effects:

[0062] 1. This harmonic suppression device alternately switches two zinc oxide resistors, making their usage nearly identical. Whenever one zinc oxide resistor participates in ferromagnetic resonance suppression, the temperature change duration of the zinc oxide resistor is compared with the temperature change duration of the other zinc oxide resistor under the same number of switching cycles, or compared with experimental data. This makes it easier to determine whether there is any abnormality in the zinc oxide resistor that was switched, and thus facilitates monitoring the performance degradation of the harmonic suppression resistor.

[0063] 2. This method can determine the temperature decay of the zinc oxide resistor in the current switching operation by using the other zinc oxide resistor as a reference when two zinc oxide resistors have different switching counts. It uses both theoretical and actual data to perform a double verification of the zinc oxide resistor in this switching operation, thereby improving the accuracy of the assessment of the zinc oxide resistor decay. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the overall structure of the harmonic elimination device according to an embodiment of this application.

[0065] Figure 2This is a flowchart illustrating the monitoring method in the embodiments of this application.

[0066] Figure 3 This is a schematic diagram of the process for evaluating performance degradation using another zinc oxide resistor in an embodiment of this application.

[0067] Figure 4 This is a schematic diagram of the process for calculating the estimated temperature decay time in the embodiments of this application.

[0068] Figure 5 This is a schematic diagram of the switching temperature decay rate in the embodiments of this application. Detailed Implementation

[0069] The following is in conjunction with the appendix Figure 1 -Appendix Figure 5 This application will be described in further detail.

[0070] This application discloses a harmonic elimination device with self-monitoring function and a monitoring method for the device. The subject executing the method can be the aforementioned harmonic elimination device or other systems and terminal devices capable of executing the aforementioned method.

[0071] See attached document Figure 1 As shown, a harmonic suppression device with self-monitoring function includes two related zinc oxide resistors connected in parallel, a temperature acquisition module, and a controller. Each branch containing a zinc oxide resistor is connected in series with a disconnect switch, which controls the switching on and off of the zinc oxide resistor in that branch. The temperature acquisition module collects temperature information from the zinc oxide resistors; an infrared thermometer can be used for this purpose. The controller controls the closing and opening of the disconnect switch and analyzes the temperature information collected by the temperature acquisition module. The output terminal of the zinc oxide resistor is grounded, and a current transformer is installed on the grounding line of the zinc oxide resistor.

[0072] The two zinc oxide resistors in this device are located in the same operating environment, such as the same temperature, humidity, and climate. Therefore, after this harmonic suppression device is put into use, after an overvoltage caused by ferroresonance, by controlling the alternating use of the two zinc oxide resistors, the aging degree of the two zinc oxide resistors is basically the same.

[0073] When a ferroresonant overvoltage occurs at the location of this harmonic suppression device, a sharp voltage rise will occur on the grounding line of the voltage transformer. At this time, the circuit breaker corresponding to one of the zinc oxide resistors is in the closed state, and the circuit breaker corresponding to the other zinc oxide resistor is in the open state. As the voltage rises, the resistance of the zinc oxide resistor corresponding to the closed circuit breaker changes from a high resistance state to a low resistance state, so that the current generated by the overvoltage can be dissipated by heat conversion at the zinc oxide resistor and then conducted to the ground, thereby achieving the purpose of suppressing resonance.

[0074] After the aforementioned ferroresonance phenomenon occurred, the temperature acquisition module collected the temperature changes of the zinc oxide resistor and transmitted the information to the controller. The controller analyzed the temperature changes of the zinc oxide resistor and concluded whether the zinc oxide resistor had become excessively aged. Based on this conclusion, the staff could decide whether to replace the excessively aged zinc oxide resistor.

[0075] After each (or a fixed number of) ferromagnetic resonance phenomenon, one of the zinc oxide resistors will undergo a temperature rise and fall process. This will open the circuit breaker of the zinc oxide resistor that participated in the ferromagnetic resonance suppression this time, and control the circuit breaker of the other zinc oxide resistor to close. This allows the other set of zinc oxide resistors to cope with the next ferromagnetic resonance phenomenon, thereby balancing the number of switching operations of the two zinc oxide resistors and making their usage nearly identical.

[0076] Each time a zinc oxide resistor involved in ferroresonance suppression undergoes a drastic temperature change, firstly, the time it takes for the resistor to cool from one temperature to another can be compared with the experimentally obtained time. If the actual temperature change time is longer than the experimentally obtained time, it indicates an abnormality in the zinc oxide resistor, requiring repair or replacement. Secondly, the temperature change times of two zinc oxide resistors under the same number of switching operations can also be compared. If the temperature change time of the switched resistor is longer than that of the unswitched resistor, it indicates an abnormality in the switched resistor, requiring repair or replacement. Thirdly, both of these comparison principles can be used simultaneously to provide more comprehensive data for reference.

[0077] In summary, when facing ferromagnetic resonance, this harmonic suppression device alternately switches two zinc oxide resistors, ensuring that the two resistors operate in nearly identical conditions. Each time one zinc oxide resistor participates in ferromagnetic resonance suppression, the duration of its temperature change is compared with the duration of the other zinc oxide resistor's temperature change after the same number of switching cycles, or compared with experimental data. This facilitates the determination of whether the switched zinc oxide resistor exhibits any abnormalities, and thus facilitates the monitoring of the harmonic suppression resistor's performance degradation.

[0078] See attached document Figure 1 and attached Figure 2 As shown, based on the above-mentioned harmonic suppression device, the monitoring method disclosed in this application includes the following processing steps:

[0079] S101. After switching any zinc oxide resistor, obtain the temperature fluctuation information of the zinc oxide resistor, the preset initial temperature value, and the termination temperature value.

[0080] In practice, after any zinc oxide resistor in this device is switched on and participates in the suppression of ferromagnetic resonance, the temperature fluctuation information, preset initial temperature value, and termination temperature value of this zinc oxide resistor are obtained through the temperature acquisition module (which can be a temperature sensor, such as an infrared thermometer).

[0081] Among them, temperature fluctuation information refers to the information on the temperature fluctuation of the zinc oxide resistor after it participates in suppressing ferromagnetic resonance. Temperature fluctuation information can reflect the changes of the zinc oxide resistor over time.

[0082] The preset initial temperature value and termination temperature value are explained as follows: The actual temperature decay time mentioned below is the time elapsed from the initial temperature value to the termination temperature value after the zinc oxide resistor has finished heating.

[0083] S102. Based on temperature fluctuation information, a temperature fluctuation curve is generated with time as the horizontal axis and temperature value as the vertical axis.

[0084] In practice, the temperature fluctuation information of the zinc oxide resistor is displayed in a two-dimensional coordinate system to form a temperature fluctuation curve. This curve can reflect the temperature fluctuation of the zinc oxide resistor from the initial temperature value to the final temperature value, or it can reflect the temperature fluctuation of the zinc oxide resistor throughout the entire heating and cooling process.

[0085] S103. In the cooling curve of the temperature fluctuation curve, match the initial time corresponding to the initial temperature value and the termination time corresponding to the termination temperature value.

[0086] S104. Based on the initial time and the termination time, generate the actual temperature decay time of the zinc oxide resistor.

[0087] In practice, the initial time corresponding to the initial temperature value and the termination time corresponding to the termination temperature value are matched in the cooling curve of the temperature fluctuation curve. Then, the initial time is subtracted from the termination time to obtain the length of time that the zinc oxide resistor takes to cool down from the initial temperature value to the termination temperature value, which is the actual temperature decay time of the zinc oxide resistor.

[0088] S105. Obtain the switching times and theoretical temperature decay table for the zinc oxide resistor.

[0089] During implementation, the number of switching operations of the zinc oxide resistor and the theoretical temperature decay table are obtained. The number of switching operations refers to the number of times the zinc oxide resistor participates in ferromagnetic resonance suppression, that is, how many times it participates in ferromagnetic resonance suppression. The theoretical temperature decay table is a table comparing the temperature decay data obtained from the experiment of the zinc oxide resistor used in this device with the number of switching operations. From this theoretical temperature decay table, the following data can be obtained, for example, after the xth switching operation of the zinc oxide resistor of this specification, it takes y minutes for the temperature to decay from the initial temperature value to the final temperature value.

[0090] S106. Match the theoretical temperature decay duration corresponding to the number of switching operations in the theoretical temperature decay table.

[0091] In practice, by matching the theoretical temperature decay time corresponding to the number of switching cycles in the theoretical temperature decay table, the theoretical temperature decay time of the zinc oxide resistor in this switching cycle can be obtained.

[0092] S107. If the actual temperature decay time is longer than the theoretical temperature decay time, an alarm message will be generated.

[0093] During implementation, the actual temperature decay time is compared with the theoretical temperature decay time. If the actual temperature decay time is longer than the theoretical temperature decay time, it indicates that the zinc oxide resistor has become abnormal, and an alarm message is generated to remind staff to carry out maintenance or replacement.

[0094] See attached document Figure 1 Appendix Figure 2 Appendix Figure 3 As shown, in step S107, if the actual temperature decay time is longer than the theoretical temperature decay time, the following processing steps are included:

[0095] S201. Obtain the reference temperature decay time of another zinc oxide resistor at the corresponding number of switching cycles.

[0096] S202. If the difference between the reference temperature decay time and the actual temperature decay time is greater than the preset temperature decay time error, an alarm message will be generated.

[0097] In practice, after comparing the actual temperature decay time of the zinc oxide resistor being switched with the theoretical temperature decay time, the actual temperature decay time can also be compared with the control temperature decay time of another zinc oxide resistor in the same device at the number of switching cycles (the actual temperature decay time and the control temperature decay time refer to the temperature decay time of the zinc oxide resistor being switched and the temperature decay time of another zinc oxide resistor at the number of switching cycles, respectively, and are distinguished by naming).

[0098] If the difference between the measured temperature decay time and the actual temperature decay time is greater than the preset temperature decay time error, it indicates that the zinc oxide resistor is very likely to have a performance abnormality. An alarm message will be generated to alert the staff to inspect or even replace the zinc oxide resistor.

[0099] The reason why the two zinc oxide resistors in this device can be compared under the same number of switching operations is that the environmental conditions such as temperature and humidity of the two zinc oxide resistors are the same, but they can be different from the test conditions. After verifying with the experimental data, they can also be verified with another zinc oxide resistor, thereby improving the accuracy of the zinc oxide resistor anomaly judgment.

[0100] See attached document Figure 1 and attached Figure 4 As shown, step S201, after obtaining another zinc oxide resistor after the reference temperature decay time corresponding to the number of cutting cycles, may further include the following processing steps:

[0101] S301. If the other zinc oxide resistor has no switching count, then obtain the switching temperature decay rate of the zinc oxide resistor, the current switching count of the other zinc oxide resistor, and the reference temperature decay time of the other zinc oxide resistor at the current switching count.

[0102] S302. Based on the reference temperature decay time, number of switching, current number of switching, and switching temperature decay rate, calculate the estimated temperature decay time for another zinc oxide resistor to reach the number of switching cycles.

[0103] In practice, due to certain special reasons, the number of times the two zinc oxide resistors in this device are switched may differ (for example, one zinc oxide resistor is under maintenance while the other is in normal use). Therefore, it is possible that the cumulative number of switching times for the zinc oxide resistor in this instance exceeds the cumulative number of switching times for the other zinc oxide resistor, making it difficult to determine whether there is an abnormality in the zinc oxide resistor after this switch based on the reference temperature decay time of the other set of zinc oxide resistors. In this case, the switching temperature decay rate of the zinc oxide resistor, the current number of switching times for the other zinc oxide resistor, and the reference temperature decay time for the other zinc oxide resistor at the current number of switching times are obtained first, and then the estimated temperature decay time for the other set of zinc oxide resistors when it reaches the number of switching times is calculated.

[0104] S303. If the actual temperature decay time of the zinc oxide resistor reaches the estimated temperature decay time of another zinc oxide resistor, an alarm message is generated.

[0105] In practice, if the actual temperature decay time of a zinc oxide resistor reaches the estimated temperature decay time of another zinc oxide resistor, it indicates that the zinc oxide resistor is very likely to experience abnormal performance degradation, and an alarm message will be generated to remind staff to carry out inspection or replacement.

[0106] The estimated duration of temperature decay can be calculated using the following formula:

[0107] ;

[0108] This is another zinc oxide resistor's estimated temperature decay time after a number of switching cycles. This is the reference temperature decay time for another zinc oxide resistor at the current switching cycle. It refers to the number of switching operations for the zinc oxide resistor. This is the current switching count of another zinc oxide resistor. It is the rate of temperature decay during switching. The difference between the number of switching operations of the two zinc oxide resistors is multiplied by the switching decay rate of the zinc oxide resistor (i.e., the time it takes for the temperature to decay after each switching operation). This gives the temperature decay time when the other zinc oxide resistor reaches the number of switching operations, which is the estimated decay time.

[0109] See attached document Figure 5 As shown, the calculation of the switching temperature decay rate can include the following processing steps:

[0110] S401. Obtain the preset sampling period.

[0111] In practice, the sampling period can be understood as follows: every certain number of switching operations (sampling period), the rate of temperature decay is recalculated. For example, if the switching period is five, then the result from the first switching to the completion of the fifth switching is one sampling period. After this sampling period, the rate of temperature decay needs to be recalculated.

[0112] S402. According to the sampling cycle, obtain the first temperature decay time after the first switching in each sampling cycle of the zinc oxide resistor, and the last temperature decay time after the last switching in each sampling cycle.

[0113] In practice, for example, in the first sampling cycle, the switching cycle is five, and the first switching is the first switching. Then, the time it takes for the temperature of the zinc oxide resistor to decay after the first switching is the first temperature decay time.

[0114] Similarly, in the first cycle, the last switch is the fifth switch, and the duration of temperature decay of the zinc oxide resistor after the fifth switch is the duration of the final temperature decay.

[0115] S403. Calculate the periodic temperature decay duration for each sampling cycle based on the first and last temperature decay durations for each sampling cycle.

[0116] In practice, the periodic decay duration within this sampling period is the sum of the last decay duration and the first temperature decay duration. This process is repeated to calculate the periodic decay duration within each sampling period, as detailed in the formula below.

[0117] S404. Based on the periodic temperature decay time and sampling period of the zinc oxide resistor, calculate the switching temperature decay rate within the sampling period.

[0118] In practice, the decay time of the temperature during each switching of the zinc oxide resistor can be reflected by dividing the periodic temperature decay time by the sampling period. See the detailed formula below.

[0119] S405. Based on the first and last switching counts of each sampling period, set the switching span range for each sampling period.

[0120] In practice, for example, if the sampling period is five, then the first cut is one and the last cut is five, so the cut span of this sampling period is [1,5]; similarly, the cut span of the next sampling period is [6,10].

[0121] S406. Establish the mapping relationship between the switching span interval and the corresponding switching temperature decay rate.

[0122] During implementation, the switching span range is linked to the corresponding switching temperature decay rate to facilitate subsequent data matching and positioning.

[0123] S407. Based on the current switching count of another set of zinc oxide resistors, match the switching span range to which the current switching count belongs, and obtain the switching temperature decay rate of the matched switching span range.

[0124] In practice, the switching span range containing the current switching count is matched, and then the switching temperature decay rate of the matched switching span range is obtained, so that the estimated temperature decay time can be calculated.

[0125] The duration of the periodic temperature decay is calculated using the following formula:

[0126] ;

[0127] It is the duration of periodic temperature decay. It is the duration of the last temperature decay in the sampling period. It is the duration of the first temperature decay in the sampling period. It is the sampling period. This refers to the number of times the zinc oxide resistor is switched at the end of each sampling cycle. The formula above is calculated by subtracting the first temperature decay time after the first switch in the sampling cycle from the last temperature decay time after the last switch.

[0128] In a preferred embodiment, this application can be further configured such that the switching temperature decay rate is calculated using the following formula:

[0129] ;

[0130] It is the temperature decay rate during the sampling cycle. It is the duration of periodic temperature decay. This is the sampling period. The above formula, which is the ratio of the periodic temperature decay time to the sampling period, yields the switching temperature decay rate of the sampling period.

[0131] The embodiments described in this specific implementation are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A harmonic suppression device with self-monitoring function, characterized in that, include: The system comprises two parallel zinc oxide resistors, a temperature acquisition module, and a controller. Each branch of the zinc oxide resistor is connected in series with a disconnect switch. The temperature acquisition module is used to collect the temperature information of the zinc oxide resistor. The controller can control the closing and opening of the disconnect switch and analyze the temperature information collected by the temperature acquisition module. The output terminal of the zinc oxide resistor is grounded, and a current transformer is installed on the grounding line of the zinc oxide resistor. This device employs the following method, which includes: After switching any zinc oxide resistor, obtain the temperature fluctuation information of the zinc oxide resistor, the preset initial temperature value, and the termination temperature value; Based on temperature fluctuation information, a temperature fluctuation curve is generated with time as the horizontal axis and temperature value as the vertical axis. In the cooling curve of the temperature fluctuation curve, match the initial time corresponding to the initial temperature value and the termination time corresponding to the termination temperature value. The actual temperature decay time of the generated zinc oxide resistor is determined based on the initial and final times. Obtain the switching cycles and theoretical temperature decay table for the zinc oxide resistor; Match the theoretical temperature decay duration corresponding to the number of switching operations in the theoretical temperature decay table; If the actual temperature decay time exceeds the theoretical temperature decay time, an alarm message will be generated.

2. A monitoring method for a harmonic suppression device, based on the harmonic suppression device with self-monitoring function as described in claim 1, characterized in that, If the actual temperature decay time is longer than the theoretical temperature decay time, then the following applies: Obtain the control temperature decay time of another zinc oxide resistor corresponding to the number of cutting cycles; If the difference between the measured temperature decay time and the actual temperature decay time is greater than the preset temperature decay time error, an alarm message will be generated.

3. The monitoring method for a harmonic suppression device according to claim 2, characterized in that, The process of obtaining another zinc oxide resistor after the reference temperature decay time corresponding to the number of cutting cycles includes: If the other zinc oxide resistor does not have the stated number of switching cycles, then obtain the switching temperature decay rate of the zinc oxide resistor, the current number of switching cycles of the other zinc oxide resistor, and the reference temperature decay time of the other zinc oxide resistor at the current number of switching cycles; Based on the reference temperature decay time, number of switching, current number of switching, and switching temperature decay rate, calculate the estimated temperature decay time for another zinc oxide resistor to reach the number of switching cycles; If the actual temperature decay time of the zinc oxide resistor reaches the estimated temperature decay time of another zinc oxide resistor, an alarm message will be generated.

4. The monitoring method for a harmonic suppression device according to claim 3, characterized in that, The estimated temperature decay time is calculated using the following formula: ； This is another zinc oxide resistor's estimated temperature decay time after a number of switching cycles. This is the reference temperature decay time for another zinc oxide resistor at the current switching cycle. It refers to the number of switching operations for the zinc oxide resistor. This is the current switching count of another zinc oxide resistor. It is the rate of temperature decay during switching.

5. The monitoring method for a harmonic suppression device according to claim 3, characterized in that, The calculation of the switching temperature decay rate includes: Obtain the preset sampling period; According to the sampling cycle, obtain the first temperature decay time after the first switch in each sampling cycle and the last temperature decay time after the last switch in each sampling cycle. The periodic temperature decay duration for each sampling cycle is calculated based on the first and last temperature decay durations for each sampling cycle. Based on the periodic temperature decay duration and sampling period of the zinc oxide resistor, the switching temperature decay rate within the sampling period is calculated. Based on the first and last number of cuts in each sampling period, the cut span range for each sampling period is set. Establish a mapping relationship between the switching span interval and the corresponding switching temperature decay rate; Based on the current switching count of another set of zinc oxide resistors, the switching span range to which the current switching count belongs is matched, and the switching temperature decay rate of the matched switching span range is obtained.

6. The monitoring method for a harmonic suppression device according to claim 5, characterized in that, The duration of the periodic temperature decay is calculated using the following formula: ； It is the duration of periodic temperature decay. It is the duration of the last temperature decay in the sampling period. It is the duration of the first temperature decay in the sampling period. It is the sampling period. It is the number of times the zinc oxide resistor is switched on and off in each sampling cycle.

7. The monitoring method for a harmonic suppression device according to claim 5, characterized in that, The switching temperature decay rate is calculated using the following formula: ； It is the temperature decay rate during the sampling cycle. It is the duration of periodic temperature decay. It is the sampling period.

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