A MOV partial valve plate performance deterioration early warning system and method

Abstract

A MOV partial valve piece performance degradation early warning system and method, comprising: the voltage reduction function of the capacitor voltage divider arranged in the spark gap trigger auxiliary loop of the series compensation complete device converts the high voltage of the primary side MOV into low voltage of the secondary side, the low voltage signal of the secondary side is processed through the MOV voltage acquisition channel to obtain the MOV voltage; the current transformer CT in the MOV current loop converts the total circuit current of the primary side MOV and the MOV branch current into small current of the secondary side, the small current of the secondary side is processed through the MOV current acquisition channel arranged in the platform measurement box to obtain the total current of the MOV and the MOV branch current; the early warning analysis processing module takes the total current of the MOV, the MOV branch current and the MOV voltage as the criterion to early warn the performance degradation of the MOV partial valve piece based on the consistency of the volt-ampere characteristic. The present application realizes the prevention of MOV damage and guarantees the safety of the MOV.

Description

Technical Field

[0001] This invention relates to the field of MOV valve plate performance testing, and specifically to an early warning system and method for performance degradation of some MOV valve plates. Background Technology

[0002] Series compensation, also known as a series compensation system, involves connecting capacitor banks in series in an AC transmission line to compensate for the line inductive reactance, thereby shortening the equivalent electrical distance of the transmission line and improving its transmission capacity and grid stability limits. The equivalent electrical principle of series compensation is as follows: Figure 1 As shown, U A Φ A This represents the voltage and phase at one end of the transmission line, and jX represents the equivalent inductive reactance of the transmission line. C U represents the capacitive reactance of a capacitor connected in series with a transmission line. B Φ B This represents the voltage and phase at the other end of the transmission line, and P represents the active power transmitted by the transmission line.

[0003] The main primary electrical equipment of the series compensation system consists of capacitor bank C, metal oxide voltage limiter MOV, spark gap GAP, bypass switch BS, damping device D, high-voltage insulation platform PF, etc. Figure 2 As shown.

[0004] Figure 2 In the diagram, C refers to the three-phase capacitor bank connected in series in the transmission line TL, used to compensate for the equivalent series impedance of the transmission line. MOV, composed of nonlinear metal oxide resistors connected in series and / or parallel, is an overvoltage protection device and a necessary measure for C overvoltage protection. GAP is a backup overvoltage protection device for the series capacitor bank, preventing equipment damage caused by C overvoltage or MOV overcurrent. BS can reliably short-circuit the capacitor bank within tens of milliseconds and also provides a means for C to be put into and taken out of operation. D is used to limit the amplitude and frequency of the C discharge current caused by GAP triggering or BS closing, ensuring the safe operation of C, GAP, and BS. The bypass disconnect switch BDS, series disconnect switch DS, and grounding switch ES provide means for system operation and maintenance.

[0005] Series compensation is connected in series in the transmission line. Once a line fault or overload occurs, an overvoltage will be generated on circuit C. When the overvoltage exceeds the inflection point voltage of the MOV, the MOV will absorb part of the fault current and limit the overvoltage below the protection level of C. However, the MOV's ability to absorb fault current, i.e., its capacity, is limited. To prevent the MOV from being damaged by overcurrent or overload, a GAP is triggered, quickly (within 1ms) transferring the fault current to the GAP circuit. Similarly, to prevent damage to the electrodes (freewheeling electrodes) of the GAP due to prolonged current flow, a command to close the BS is issued simultaneously with triggering the GAP. Under normal circumstances, the BS will close within tens of milliseconds, transferring the fault current to the BS circuit.

[0006] MOVs are composed of nonlinear metal oxide varistors (also called "resistors") connected in series and / or parallel. Due to the nonlinear volt-ampere characteristics of these varistors, such as... Figure 3 As shown, Disk Voltage represents the valve plate voltage, FACTS ProtectorBank VI Curve Including Spares represents the volt-ampere characteristic curve of the flexible transmission protection device (MOV) (including spares), and Column Current (amps peak) represents the column current (peak value). When the overvoltage across the MOV exceeds the inflection point voltage of the MOV, it exhibits a low resistance state, thereby limiting the transient overvoltage across the MOV, while it exhibits a high resistance under normal power frequency voltage.

[0007] When an MOV (Metal Oxide Valves) operates with voltage limiting, it is in a low-resistance state, resulting in a large fault current flowing through it, i.e., absorbing a significant amount of energy. To meet high-capacity requirements, multiple MOVs are connected in parallel. Each MOV connected in parallel should have strictly consistent volt-ampere characteristics to ensure good current sharing among all MOVs in the entire parallel group. Otherwise, if the performance (volt-ampere characteristic) of a single MOV is abnormal, absorbing too much fault current (excessive energy) will lead to overload and overheating damage. Existing series compensation protection for MOV valve plate performance (or current sharing characteristics) is MOV imbalance protection. Its method is to divide the multiple parallel MOVs into two groups and detect the branch currents of the two groups of MOVs (…). Figure 2 The MOV equipment status is detected by the consistency (imbalance) of CT2 and CT3. Under normal circumstances, because multiple parallel MOVs have good current sharing characteristics, after being divided into two groups, the current of each group of MOVs should be the same. If the performance of a certain MOV is abnormal, the MOV in that group will have a larger current flowing through it. When the current imbalance between the two groups of MOVs reaches the protection setting, the MOV current imbalance protection will be activated.

[0008] Based on existing operation and maintenance experience, when the MOV imbalance protection in the series compensation protection system trips, the MOV has generally already experienced pressure release or combustion, meaning the MOV equipment is damaged. This is mainly because when a near-end fault occurs within the series compensation zone (the transmission line where the series compensation is located), the capacitor bank overvoltage is significant. After the MOV voltage limiting action, the fault current flowing through the two branches of the MOV is substantial. When the MOV valve plate performance deteriorates, the large fault current flowing through the abnormal valve plate will directly cause damage to the abnormal valve plate, leading to abnormalities and damage to adjacent valve plates. Furthermore, the development speed of this fault process is extremely rapid (MOV through-breakdown), and the MOV imbalance protection's action speed is insufficient to clear the fault before MOV through-breakdown, thus failing to ensure equipment safety. Currently, the only way to confirm MOV damage is through the MOV imbalance protection, issuing a permanent blocking command for series compensation reactivation to prevent the faulty equipment from being put back into use without proper maintenance. Summary of the Invention

[0009] To address the issue that, based on existing maintenance experience, when the MOV imbalance protection in series compensation protection activates, the MOV has essentially already experienced pressure release or combustion / explosion, meaning the MOV equipment is damaged, this invention proposes an early warning system for the performance degradation of some MOV valve plates, comprising:

[0010] The voltage reduction function of the capacitor voltage divider in the spark gap triggering auxiliary circuit of the series compensation assembly converts the high voltage of the primary side MOV into the low voltage of the secondary side. The low voltage signal of the secondary side is processed by the MOV voltage acquisition channel in the platform measurement box to obtain the MOV voltage.

[0011] The current transformers (CTs) installed in each current loop of the MOV in the series compensation assembly convert the primary side MOV total loop current and MOV branch current into secondary side small currents. The secondary side small currents are processed by the MOV current acquisition channel installed in the platform measurement box to obtain the MOV total current and MOV branch current.

[0012] The early warning analysis and processing module is configured in the series compensation protection device and is connected to the platform measurement box. It is used to provide early warning of the performance degradation of some valve plates in the MOV based on the total current of the MOV, the branch current of the MOV and the voltage of the MOV, with the consistency of the volt-ampere characteristics as the criterion.

[0013] The series compensation assembly includes a series compensation relay protection device.

[0014] Optionally, the MOV voltage acquisition channel adopts a two-stage design. The first-stage design includes: resistor R1, resistor R2, resistor R11, capacitor C11, and operational amplifier U1.

[0015] Resistor R1 and resistor R2 are connected in parallel and then connected to one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C11 and the positive input terminal of operational amplifier U1. The other end of capacitor C11 is grounded. The output terminal of operational amplifier U1 is connected to the negative input terminal of operational amplifier U1. The negative power supply of operational amplifier U1 is grounded.

[0016] The secondary design includes: resistor R12, capacitor C12, and ADC sampling module;

[0017] One end of resistor R12 is connected to the output of operational amplifier U1, and the other end is connected to one end of capacitor C12 and the input of ADC sampling module, respectively. The other end of capacitor C12 is grounded.

[0018] Optionally, the MOV current acquisition channel adopts a three-level module design, the first-level module including: a sensor, a resistor RL and a TVS tube;

[0019] The sensor is connected in parallel with a resistor RL and a TVS diode, respectively.

[0020] The second-level module includes: resistors R22, R23, R24, and R25, as well as operational amplifier U2;

[0021] One end of resistors R22 and R23 is connected to the two ends of the TVS transistor, respectively. The other end of resistor R22 is connected to the positive input terminal of transport amplifier U2 and one end of resistor R24, respectively. The other end of resistor R24 ​​is grounded. The other end of resistor R23 is connected to the negative input terminal of transport amplifier U2 and one end of resistor R25, respectively. The other end of resistor R25 is connected to the output terminal of operational amplifier U2. The negative power supply of operational amplifier U2 is grounded.

[0022] The third-level module includes: resistor R21, capacitor C21, and ADC sampling module;

[0023] One end of resistor R21 is connected to the output of operational amplifier U2, and the other end is connected to one end of capacitor C21 and the ADC sampling module. The other end of capacitor C21 is grounded.

[0024] Optionally, the early warning analysis and processing module is specifically used for:

[0025] The total current, branch current, and voltage of the MOV are processed to obtain the current current-voltage characteristic data;

[0026] The consistency between the current current-voltage characteristic data and the current-voltage characteristic curve fitted at the factory is judged to achieve early warning of the performance degradation of some valve plates in MOV.

[0027] Optionally, the early warning analysis and processing module performs consistency judgment between the current volt-ampere characteristic data and the volt-ampere characteristic curve fitted at the factory, thereby realizing early warning of performance degradation of some valve plates in the MOV. The specific implementation steps include:

[0028] Based on the current volt-ampere characteristic data and the volt-ampere characteristic curve at the time of manufacture, calculate the deviation of the total MOV current value and the deviation of the MOV branch current value corresponding to the same MOV voltage value.

[0029] Determine whether the deviation of the total current value of the MOV or the deviation of the current value of the MOV branch meets the set warning conditions. If it does, the performance of the MOV valve plate deteriorates and a warning message is issued. Otherwise, the performance of the MOV valve plate does not deteriorate and no warning message is issued.

[0030] Optionally, the set warning conditions include:

[0031] The deviation of the current value corresponding to the same voltage value exceeds the set threshold, and the number of voltage values ​​whose current value deviation exceeds the set threshold is greater than the set number.

[0032] Furthermore, this invention also provides a method for early warning of performance degradation of some valve plates in an MOV, including:

[0033] The primary side MOV total circuit current and MOV branch current are converted into secondary side small currents by the current transformers CT installed in each current loop of the MOV in the series compensation complete device. The secondary side small currents are processed by the MOV current acquisition channel installed in the platform measurement box to obtain the MOV total current and MOV branch current.

[0034] The high voltage of the primary MOV is converted into a low voltage of the secondary side by the voltage reduction function of the capacitor voltage divider in the spark gap triggering auxiliary circuit of the series compensation assembly. The low voltage signal of the secondary side is processed by the MOV voltage acquisition channel in the platform measurement box to obtain the MOV voltage.

[0035] The early warning analysis and processing module configured in the series compensation relay protection device provides early warning of the performance degradation of some valve plates in the MOV based on the total MOV current, MOV branch current and MOV voltage, with the consistency of volt-ampere characteristics as the criterion.

[0036] The series compensation assembly includes a series compensation relay protection device.

[0037] Optionally, the early warning analysis and processing module configured in the series compensation relay protection device, based on the total MOV current, MOV branch current, and MOV voltage, and using the consistency of the volt-ampere characteristics as a criterion, provides an early warning of performance degradation of some valve plates in the MOV, including:

[0038] The total MOV current, MOV branch current, and MOV voltage are processed to obtain the current volt-ampere characteristic data;

[0039] By comparing the current current-voltage characteristic data with the current-voltage characteristic curve at the time of manufacture, an early warning can be given for the performance degradation of some valve plates in the MOV.

[0040] Optionally, the step of verifying the consistency between the current volt-ampere characteristic data and the volt-ampere characteristic curve at the time of manufacture to achieve early warning of performance degradation of some valve plates in the MOV includes:

[0041] Based on the current volt-ampere characteristic data and the volt-ampere characteristic curve at the time of manufacture, calculate the deviation of the total MOV current value and the deviation of the MOV branch current value corresponding to the same MOV voltage value.

[0042] Determine whether the deviation of the total current value of the MOV or the deviation of the current value of the MOV branch meets the set warning conditions. If it does, the performance of the MOV valve plate deteriorates and a warning message is issued. Otherwise, the performance of the MOV valve plate does not deteriorate and no warning message is issued.

[0043] Optionally, the acquisition of MOV voltage via a capacitor voltage divider in the spark gap triggering auxiliary circuit of the series compensation assembly and an MOV voltage acquisition channel in the platform measurement box includes:

[0044] The MOV voltage input signal Vin is divided by resistors R1 and R2 in the MOV voltage acquisition channel and then input to the operational amplifier U1 via a side filter composed of resistor R11 and capacitor C11. The output of the operational amplifier U1 is then filtered through the output terminal composed of resistor R12 and capacitor C12 and input to the ADC sampling module to obtain the MOV voltage.

[0045] Specifically, the input signal CT8_I of the MOV total current passes through resistor RL in the MOV total current acquisition channel, then through the signal amplification and conversion stage composed of resistor R22 and operational amplifier U2, and finally through the analog-to-digital conversion stage composed of resistor R21, capacitor C21 and ADC sampling module.

[0046] Furthermore, this application also provides a computing device, comprising: at least one processor and a memory;

[0047] The memory is used to store one or more programs;

[0048] When the one or more programs are executed by the at least one processor, a method for early warning of performance degradation of MOV partial valve plates as described above is implemented.

[0049] In another aspect, this application also provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements the above-described method for early warning of performance degradation of MOV partial valve plates.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] This invention provides an early warning system for the performance degradation of MOV valve plates, comprising: a capacitor voltage divider installed in the spark gap trigger auxiliary circuit of the series compensation assembly to convert the high voltage of the primary side MOV into a low voltage of the secondary side; the low voltage signal of the secondary side is processed by the MOV voltage acquisition channel installed in the platform measurement box to obtain the MOV voltage of the metal oxide voltage limiter; current transformers (CTs) installed in each current circuit of the MOV in the series compensation assembly to convert the total circuit current and branch current of the primary side MOV into small currents of the secondary side; the small currents of the secondary side are processed by the MOV current acquisition channel installed in the platform measurement box to obtain the total current of the MOV and the branch current of the MOV; and an early warning analysis and processing module configured in the series compensation relay protection device and communicatively connected to the platform measurement box, used to provide early warning of the performance degradation of the MOV valve plates based on the total current of the MOV, the branch current of the MOV, and the MOV voltage, with the consistency of the volt-ampere characteristics as the criterion. This invention directly uses the consistency of MOV volt-ampere characteristics as a criterion, and improves the protection range of MOV by providing early warning of the performance degradation of some valve plates in MOV, thereby preventing MOV damage and ensuring MOV safety. Attached Figure Description

[0052] Figure 1 This is an equivalent electrical schematic diagram of a series compensation device in the prior art;

[0053] Figure 2 This is a typical circuit diagram of the series compensation device of the present invention;

[0054] Figure 3 This is a schematic diagram of the typical nonlinear current-voltage characteristic curve of the MOV of the present invention;

[0055] Figure 4 This is a schematic diagram of the MOV capacitor voltage divider of the present invention;

[0056] Figure 5 This is a schematic diagram of the hardware principle of the newly added MOV voltage acquisition channel in this invention;

[0057] Figure 6 This is a circuit diagram of the newly added MOV total current measurement CT series compensation device of the present invention;

[0058] Figure 7 This is a schematic diagram of the hardware principle of the newly added MOV total current acquisition channel in this invention;

[0059] Figure 8 This is a dimensional diagram of the dry hollow CT scanner of the present invention;

[0060] Figure 9 This is a schematic diagram showing the proposed location of the CT in the MOV total current loop of the present invention;

[0061] Figure 10 This is a schematic diagram of an early warning system for performance degradation of a portion of the valve plate in an MOV according to the present invention;

[0062] Figure 11 This is a flowchart of the early warning logic discrimination of the present invention;

[0063] Figure 12 This is a schematic diagram of an electronic device structure according to the present invention. Detailed Implementation

[0064] Existing MOV protection typically targets near-end faults within the protection zone, where capacitor bank overvoltages are significant. After MOV voltage limiting operation, the fault current flowing through the MOV is substantial. However, faults occurring at the far end of the protection zone or on lines outside the zone can also cause MOV voltage limiting operation, although the MOV current is smaller and does not meet the conditions for MOV overcurrent protection operation. This type of MOV voltage limiting operation is defined as the first type of MOV voltage limiting operation. Traditional series compensation protection considers this condition a through-fault for the MOV, therefore it does not monitor this type of MOV voltage limiting operation, nor has it considered using this relatively small MOV current for equipment performance assessment. Although this small MOV current exceeds the boundary conditions of existing MOV protection operation, it can actually reflect the current performance of the operating equipment. Therefore, a method for early warning of MOV valve plate performance degradation under the first type of MOV voltage limiting operation is proposed as a basic approach to optimizing MOV protection.

[0065] This invention proposes a method for early warning of performance degradation of MOV valve plates. It measures the current flowing through the MOV during line faults (including smaller MOV currents during faults in remote areas or outside the area, which existing unbalanced protection cannot operate), and simultaneously measures the MOV voltage. Using the measured MOV current and voltage, it collects current MOV volt-ampere characteristic data, and compares the collected data with the factory-set volt-ampere characteristic curve to predict and warn of performance degradation of MOV valve plates. Since the MOV volt-ampere characteristic reflects the current / voltage characteristics of the entire MOV group, it is necessary to collect the smaller amplitude of the entire MOV current (total MOV current). Therefore, an additional method for collecting the total MOV current is proposed to ensure the accuracy of early warning of MOV valve plate performance degradation. This total MOV current is the sum of the currents of the two MOV branches; therefore, cross-checking among the three current quantities improves the accuracy of MOV volt-ampere characteristic consistency judgment.

[0066] To better understand the present invention, the following description, in conjunction with the accompanying drawings and embodiments, will further illustrate the content of the present invention.

[0067] Example 1:

[0068] An early warning system for performance degradation of partial valve plates in MOV, such as Figure 10 As shown, it includes:

[0069] The voltage reduction function of the capacitor voltage divider C1 to C5 in the spark gap triggering auxiliary circuit of the series compensation assembly converts the high voltage of the primary side MOV into the low voltage of the secondary side. The low voltage signal of the secondary side is processed by the MOV voltage acquisition channel in the platform measurement box to obtain the MOV voltage.

[0070] The current transformers (CTs) installed in each current loop of the MOV in the series compensation assembly convert the primary side MOV total loop current and MOV branch current into secondary side small currents. The secondary side small currents are processed by the MOV current acquisition channel installed in the platform measurement box to obtain the MOV total current and MOV branch current.

[0071] The early warning analysis and processing module is configured in the series compensation relay protection device and is communicatively connected to the platform measurement box. It is used to provide early warning of the performance degradation of some valve plates in the MOV based on the total current of the MOV, the branch current of the MOV and the voltage of the MOV, with the consistency of the volt-ampere characteristics as the criterion.

[0072] Optionally, the voltage reduction function of capacitor dividers C1 to C5 in the spark gap triggering auxiliary circuit of the series compensation assembly converts the high voltage of the primary side MOV into a low voltage of the secondary side. The low voltage signal of the secondary side is then processed by the MOV voltage acquisition channel in the platform measurement box to obtain the MOV voltage. The specific implementation steps include:

[0073] Utilizing the parallel relationship between the MOV and the spark gap (MOV voltage equals spark gap voltage), the high voltage of the primary MOV is converted to a low voltage on the secondary side by the voltage reduction function of the capacitor divider in the auxiliary circuit triggered by the spark gap. This low voltage signal is then transmitted to the signal conditioning board of the platform measurement box via a secondary cable. The signal conditioning board performs isolation, protection, and filtering on this low voltage signal, converting it into a standard analog voltage signal before transmitting it to the AD conversion module. The AD conversion module performs analog-to-digital conversion, converting the analog signal into a digital signal. The electro-optical conversion module then converts the digital electrical signal into a digital optical signal, which is transmitted via optical fiber to the series compensation protection device. This completes the acquisition of the MOV voltage by the series compensation protection device. Figure 10 As shown.

[0074] Optionally, the current transformers (CTs) installed in each current loop of the MOV in the series compensation assembly convert the primary side MOV total loop current and MOV branch current into secondary side small currents. These secondary side small currents are then processed by the MOV current acquisition channel installed in the platform measurement box to obtain the MOV total current and MOV branch current. Specific implementation steps include:

[0075] The current transformers (CTs) installed in each circuit of the MOV convert the primary side MOV total circuit current, MOV1 branch current, and MOV2 branch current into secondary side small currents. These secondary side small current signals are then transmitted to the signal conditioning board of the platform measurement box via secondary cables. The signal conditioning board performs isolation, protection, and filtering on these small current signals, converting them into standardized analog current signals before transmitting them to the AD conversion module. The AD conversion module performs analog-to-digital conversion on these analog signals, converting them into digital signals. The electro-optical conversion module then converts the digital electrical signals into digital optical signals, which are transmitted via optical fiber to the series compensation protection device. This completes the acquisition of MOV current by the series compensation protection device. Figure 10 As shown.

[0076] In existing series compensation protection systems, when the MOV imbalance protection activates, the MOV has essentially already undergone pressure release or combustion / explosion, meaning the MOV equipment is damaged. The specific reasons are as follows:

[0077] 1) MOV current imbalance protection is designed for situations where a near-end fault occurs within the series compensation zone (the transmission line where the series compensation is located). In such cases, the overvoltage across the capacitor bank is high, and after the MOV voltage limiting action, the fault current flowing through the two branches of the MOV is substantial. If the MOV varistors deteriorate, the large fault current flowing through these deteriorated varistors can cause them to fail, leading to the successive failure of adjacent varistors and ultimately resulting in a complete breakdown of the MOV. Due to the extremely rapid fault development, by the time the MOV imbalance protection detects that the imbalance has reached its protection setting, the MOV has already failed. Therefore, it is impossible to clear the fault and ensure equipment safety before the MOV fails.

[0078] 2) For the small MOV current during line faults at remote ends within the zone or outside the zone, it is usually considered a through fault (a fault that will not adversely affect the performance of the MOV). Therefore, such MOV operating conditions are not monitored, and so far, such small MOV currents have not been used to determine equipment performance.

[0079] 3) The existing performance evaluation criteria for MOV equipment is to divide multiple parallel MOVs into two groups (two MOV branches) and then evaluate the current sharing characteristics between the groups (i.e., the current in the two MOV branches). The so-called current sharing characteristics are actually a reflection of the consistency of the MOV's volt-ampere characteristics, so directly evaluating the consistency of the MOV's volt-ampere characteristics is more accurate and reliable.

[0080] Since the current MOV equipment performance assessment only requires the MOV branch current, the platform measurement box does not collect the MOV voltage signal. Therefore, the series compensation relay protection device cannot obtain the MOV voltage signal, and thus cannot fit the actual MOV volt-ampere characteristic curve with the MOV current. The existing capacitor equalization circuit in the GAP trigger auxiliary circuit is used to achieve voltage equalization control of the MOV voltage, thereby realizing the trigger conduction control of the GAP main circuit. Therefore, this capacitor equalization circuit is only used for the trigger conduction control of the GAP main circuit.

[0081] Therefore, it is necessary to improve the existing MOV imbalance protection. By adding an early warning function for the performance degradation of some MOV valve plates, the protection scope of MOV can be expanded, MOV damage can be prevented, and MOV safety can be ensured.

[0082] This invention addresses the aforementioned problems by upgrading the existing capacitor voltage equalization circuit in the GAP trigger auxiliary circuit and adding... Figure 4 The capacitive voltage dividers C1-C5 in the system are upgraded to have MOV voltage acquisition capabilities, and the voltage measurement signal is introduced into the series compensation measurement system (platform measurement box). Simultaneously, hardware design for the MOV voltage acquisition channel is added to the platform measurement box, including filtering, AD conversion (analog-to-digital conversion), data processing, and electro-optic conversion. Then, using the measured MOV current and MOV voltage, the volt-ampere characteristic data at the moment of MOV voltage limiting action can be obtained, and its consistency is compared with the MOV volt-ampere characteristic curve at the factory. Here, A, B, and C represent the three main electrodes of the GAP, T1, T2, and T3 respectively. 2、 T 3、 T4 represents the pulse transformer, R1 and R2 represent current-limiting resistors, and GTCB represents the GAP trigger control box.

[0083] The MOV voltage acquisition channel adopts a two-stage design. The first stage design includes: resistor R1, resistor R2, resistor R11, capacitor C11, and operational amplifier U1.

[0084] Resistor R1 and resistor R2 are connected in parallel and then connected to one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C11 and the positive input terminal of operational amplifier U1. The other end of capacitor C11 is grounded. The output terminal of operational amplifier U1 is connected to the negative input terminal of operational amplifier U1. The negative power supply of operational amplifier U1 is grounded.

[0085] The secondary design includes: resistor R12, capacitor C12, and ADC sampling module;

[0086] One end of resistor R12 is connected to the output of operational amplifier U1, and the other end is connected to one end of capacitor C12 and the input of ADC sampling module, respectively. The other end of capacitor C12 is grounded.

[0087] Figure 4 As shown in C1-C4, a large-capacitance voltage divider capacitor is connected in series, as shown in capacitor voltage dividers C1-C5 in the figure, thus forming a voltage divider capacitor with the existing four GAP equalizing capacitors. The parameters of the voltage divider capacitor should be determined in conjunction with the technical parameters of the equalizing capacitors in different SC projects and the requirements of the platform measurement box for the voltage measurement input signal. Although capacitor voltage dividers C1-C5 measure the voltage across the GAP, considering the parallel connection between the MOV and the GAP, and that the MOV valve plate performance degradation warning is mainly based on the equipment performance judgment under the first type of MOV voltage limiting action condition, the GAP has not yet been triggered to conduct at this time, and the voltage across the GAP is equal to the voltage across the MOV.

[0088] Hardware design scheme for MOV voltage acquisition channel. The newly added MOV voltage acquisition channel hardware circuit is divided into two levels of design, such as... Figure 5 As shown. The first stage consists of resistors R1, R2, and R11, capacitor C11, and operational amplifier U1. The MOV voltage input signal Vin is divided by R1 and R2, filtered at the input side (R11, C11), and then fed into operational amplifier U1, which acts as a voltage follower. The second stage consists of resistor R12, capacitor C12, and an ADC sampling module. The voltage signal is then filtered at the output end (R12, C12) before being fed into the ADC sampling module. Usam represents the MOV sampling voltage input to the ADC chip.

[0089] The sampling frequency of the newly added MOV voltage is controlled by the series compensation relay protection device, maintaining consistency with the existing MOV1 current, MOV2 current, GAP current, capacitor current, etc., and keeping the same sampling frequency per cycle. The sampled data is connected to the existing platform measurement box of the series compensation and transmitted to the series compensation control and protection system along with the existing analog signals.

[0090] The MOV current acquisition channel adopts a three-level module design. The first-level module includes: a sensor, a resistor RL, and a TVS tube.

[0091] The sensor is connected in parallel with a resistor RL and a TVS diode, respectively.

[0092] The second-level module includes: resistors R22, R23, R24, and R25, as well as operational amplifier U2;

[0093] One end of resistors R22 and R23 is connected to the two ends of the TVS transistor, respectively. The other end of resistor R22 is connected to the positive input terminal of transport amplifier U2 and one end of resistor R24, respectively. The other end of resistor R24 ​​is grounded. The other end of resistor R23 is connected to the negative input terminal of transport amplifier U2 and one end of resistor R25, respectively. The other end of resistor R25 is connected to the output terminal of operational amplifier U2. The negative power supply of operational amplifier U2 is grounded.

[0094] The third-level module includes: resistor R21, capacitor C21, and ADC sampling module;

[0095] One end of resistor R21 is connected to the output of operational amplifier U2, and the other end is connected to one end of capacitor C21 and the ADC sampling module. The other end of capacitor C21 is grounded.

[0096] The MOV current acquisition channel includes the MOV total current acquisition channel and the MOV branch current acquisition channel.

[0097] The design range of the MOV total current acquisition channel is relatively large, requiring the addition of a new MOV total current acquisition CT. Because the MOV volt-ampere characteristics reflect the current / voltage characteristics of the entire MOV group, it is necessary to acquire the relatively small amplitude of the entire MOV current (MOV total current). Therefore, a design scheme to add a MOV total current acquisition is proposed, namely, adding a CT8 to the MOV total current loop. Figure 6 As shown, CT1, CT4, CT5, CT6, CT7, and CT8 represent current transformers for collecting line current, platform flashover current, capacitor current, capacitor unbalanced current, GAP current, and MOV total current. The specific installation location of CT8 is shown in [reference needed]. Figure 9 This means it is installed on the MOV circuit busbar. For compatibility considerations, the MOV circuit busbar is considered to be made of 250mm diameter aluminum alloy (maximum diameter, may vary depending on the series compensation). The CT technical parameters can be adjusted appropriately according to the characteristics of the measured current. The structural design can refer to other circuit CTs, and a dry hollow CT is adopted. Figure 8 Taking the medium-sized CT as an example, the CT dimensions are: inner diameter of the core 290mm, outer diameter of the CT 482mm, thickness of the core sheath 300mm, thickness of the CT 140mm, and height of the CT + mounting base 618mm. The MOV circuit can be installed in 800mm of space. This solution is feasible, and R10 indicates the chamfer of the mounting base.

[0098] Hardware design scheme for MOV total current acquisition channel. The hardware design of the newly added MOV total current transformer CT8 secondary current acquisition channel is based on a three-level module design, such as... Figure 7As shown. The first stage mainly consists of a sensor, resistor RL, and a TVS diode. The TVS diode normally operates in an open-circuit state, only clamping protection occurs when the CT8 current exceeds 20 times the rated current, generating a transient high voltage. The second stage mainly consists of resistors R22-R25 and operational amplifier U2, forming a differential analog signal acquisition circuit. The third stage mainly consists of resistor R21, capacitor C21, and an ADC sampling module. The output of the differential circuit is filtered (R21, C21) before being connected to the ADC sampling module. Iin represents the total MOV current signal after sensor isolation, and CT8_I and CT8_Γ represent the two ends of the total MOV current signal from the secondary side of CT8.

[0099] The sampling frequency of the MOV total current CT8 is controlled by the series compensation relay protection device, and the sampling control method is the same as the series compensation MOV voltage sampling control method mentioned in this application.

[0100] Hardware design scheme for MOV branch current acquisition channel. The hardware design of the secondary current acquisition channel of CT (CT2 and CT3) for MOV branch current is based on a three-level module design, such as... Figure 7 As shown. The first stage mainly consists of a sensor, resistor RL, and a TVS diode. The TVS diode normally operates in an open-circuit state, only clamping protection occurs when the currents of CT2 and CT3 exceed 20 times their rated current, generating transient high voltage. The second stage mainly consists of resistors R22-R25 and operational amplifier U2, forming a differential analog signal acquisition circuit. The third stage mainly consists of resistor R21, capacitor C21, and an ADC sampling module. The output of the differential circuit is filtered (R21, C21) before being connected to the ADC sampling module.

[0101] The fitting of the MOV's factory-delivered volt-ampere characteristic curve can be completed using test data from the MOV residual voltage test. The curve is then embedded into the application software before the series compensation relay protection device is commissioned at the factory, and can be called by the MOV valve plate performance degradation early warning analysis module.

[0102] The MOV valve plate performance degradation early warning and judgment logic judges the consistency between the current MOV volt-ampere characteristic data and the MOV volt-ampere characteristic curve at the factory. The deviation range should be configurable. If the voltage value deviation corresponding to multiple (about 10) current values ​​exceeds 5%, it can be considered that there is an inconsistency between the current MOV volt-ampere characteristic data and the MOV volt-ampere characteristic curve at the factory.

[0103] This invention directly uses the consistency of MOV volt-ampere characteristics as a criterion, and improves the protection range of MOV by providing early warning of the performance degradation of some valve plates in MOV, thereby preventing MOV damage and ensuring MOV safety.

[0104] This paper addresses several key issues: MOV voltage acquisition for MOV volt-ampere characteristic data collection; ensuring acquisition accuracy when MOV current is low due to line faults in remote areas or outside the area; hardware design issues related to newly added current and voltage signal acquisition loops; a consistency discrimination algorithm for MOV volt-ampere characteristics; and early warning logic for performance degradation of some MOV valve plates. Figure 11 As shown, the warning judgment activation condition is: when the MOV voltage is greater than the activation value and there is no series compensation protection action, the warning judgment is activated; when the MOV voltage is less than the activation value or there is a series compensation protection action, the warning judgment is terminated. The aim is to completely record the instantaneous values ​​of MOV voltage and total MOV current during the MOV voltage limiting operation. In the figure, m++ represents the counter, indicating the number of sampling points that meet the warning conditions before the warning judgment is activated and terminated; n++ represents the counter, indicating the number of sampling points that meet the warning conditions before the warning judgment is activated and terminated; and k represents the percentage set value of sampling points that meet the warning conditions before the warning judgment is activated and terminated.

[0105] The warning action condition is: the number of sampling points n used for warning judgment is greater than the set value N, and the percentage of sampling points that meet the warning condition is greater than k%. The symbols in the figure are explained as follows:

[0106] I m2 I m3 I m8 : respectively Figure 4 The MOV current values ​​corresponding to the MOV cell currents measured by CT2, CT3, and CT8; U cap I0: Measured instantaneous MOV voltage value, i.e., instantaneous MOV terminal voltage value; I1: Measured instantaneous MOV total current value; U0: Measured instantaneous MOV voltage value. cap The current value corresponds to the factory default VI; n: counter, the number of sampling points before the warning judgment ends after the warning judgment is started; m: counter, the number of sampling points that meet the warning conditions before the warning judgment ends after the warning judgment is started; U: warning judgment start setting value; x: relative deviation percentage setting value of MOV total current when the voltage limiting action is performed.

[0107] The specific details are as follows:

[0108] 1) A method for early warning of MOV valve plate performance degradation is used. This method measures the current flowing through the MOV during line faults, especially the relatively small MOV current during faults in remote areas or outside the area. Such small MOV currents are unlikely to cause continuous valve plate abnormalities (MOV imbalance protection will not activate). Simultaneously, MOV voltage measurement is added. The measured MOV current and voltage are used to collect MOV volt-ampere characteristic data. The collected MOV volt-ampere characteristic data is compared with the factory-set volt-ampere characteristic curve, thereby enabling the prediction and early warning of MOV valve plate performance degradation. This solves the problem that MOV imbalance protection cannot clear faults and ensure equipment safety before MOV failure.

[0109] 2) Because the existing MOV imbalance protection only considers whether the current flowing through the two branches of the MOV is balanced when it operates normally, only CTs (CT2 and CT3) are set up to measure the current of the MOV branches. However, the warning judgment should be based on the volt-ampere characteristics of the entire MOV group, so the total MOV current needs to be used. In order to ensure the measurement accuracy of the total MOV current and even the final warning accuracy, this invention proposes a solution to measure the total MOV current in the MOV total circuit (if the original method of summing the MOV branch currents is used, there is a risk of measurement error superposition).

[0110] 3) The volt-ampere characteristics of MOV are the most direct and effective method to verify the performance of MOV valve plates. By collecting MOV voltage (capacitor bank overvoltage) and MOV current, the actual volt-ampere characteristics of the MOV in operation can be obtained. Therefore, directly determining the consistency between the current volt-ampere characteristics of the MOV and the factory-issued volt-ampere characteristics will more accurately and reliably detect potential performance degradation of some MOV valve plates.

[0111] The first type of MOV voltage limiting operation refers to a situation where, when the voltage limiting action occurs, the current flowing through the MOV does not reach the current corresponding to the MOV overcurrent protection or the time delay protection setting value. Since this operation has little impact on the performance of the MOV equipment, the MOV overcurrent protection will not trip under this condition. The basic characteristics of the MOV current under this condition can be extracted from the actual fault recording data of the series compensation protection. At this time, the MOV current waveform is a steeply rising and slowly falling triangular wave.

[0112] Depend on Figure 2As can be seen from the SC circuit topology, the data reflecting the overall volt-ampere characteristics of the MOV overvoltage operation includes two sets: the total MOV current and MOV voltage measured by current sensor CT8, and the sum of the MOV branch currents and MOV voltage measured by current sensors CT2 and CT3. Combining whether the total MOV current reaches the MOV overcurrent protection operation condition during MOV overvoltage operation, the MOV valve performance degradation warning conditions can be divided into two categories: the first type of MOV voltage limiting operation condition and the second type of MOV high current operation condition. Under the first type of MOV voltage limiting operation condition, if the three current measurements satisfy the relationship that the total current equals the sum of the two branch currents, the current of CT8 and the MOV voltage are used as the current overall volt-ampere characteristic detection data of the MOV. Furthermore, the closer the measured MOV current is to the MOV overcurrent protection setting, the more complete and reliable the overall volt-ampere characteristic detection data.

[0113] The second type of MOV voltage limiting operation refers to a situation where, when the voltage limiting action is activated, the current flowing through the MOV exceeds the corresponding current and time delay protection setting values ​​of the MOV overcurrent protection. Under this condition, the MOV overcurrent protection will activate, and the MOV current waveform will be a rectangular wave with a steep rise and fall.

[0114] Under the second type of MOV voltage limiting operation, the MOV current rises rapidly, and after the MOV overcurrent protection trips, the GAP triggers conduction, causing the MOV current to quickly return to zero. Although the number of MOV current sampling data points (approximately 20) is considerable, they are primarily concentrated in the high-current region of the MOV, with very few low-current sampling data points, making it largely impossible to reflect the overall volt-ampere characteristic (VI) of the entire MOV group. However, considering that the voltage limiting operation may occur more than once under the second type of MOV voltage limiting operation, it is highly likely that it will include the first type of MOV voltage limiting operation. In this case, the volt-ampere characteristic of the entire MOV group can be detected through the sampling data from the included first type of MOV voltage limiting operation.

[0115] 1) Upgrade the gap equalization circuit to enable it to function as a capacitor voltage divider and design an MOV voltage measurement circuit in the platform measurement system. Combine the actual measured MOV voltage and MOV current to obtain the current volt-ampere characteristics of the MOV. Use the consistency between the current volt-ampere characteristics and the factory volt-ampere characteristics as the criterion to provide early warning of the performance degradation of the MOV valve plates.

[0116] 2) The MOV volt-ampere characteristics used for early warning should be the volt-ampere characteristics of the entire MOV group. It is proposed to add a total MOV current measurement CT8 to the MOV total circuit. By directly measuring the MOV total circuit current, the measurement accuracy of MOV current is effectively improved, laying the foundation for the accuracy of the collected MOV volt-ampere characteristic data.

[0117] 3) When the MOV branch current is large, an auxiliary criterion is proposed to fit two MOV branch volt-ampere characteristic curves and one MOV total circuit volt-ampere characteristic curve respectively, and then compare the consistency of the three actual MOV volt-ampere characteristic curves, thereby improving the accuracy and reliability of early warning of performance degradation of MOV valve plates.

[0118] 4) By leveraging the inherent logical relationship between the total MOV current and the currents of the two MOV branches, the accuracy of the MOV current acquisition circuit is verified, improving the reliability of MOV current measurement. Under normal circumstances, the total MOV current is the sum of the currents of the two MOV branches originally used for MOV unbalance protection. If the three measured currents do not satisfy the summation relationship, the current value I of a single MOV unit corresponding to the current measured by the three current transformers can be calculated. m The calculation method is shown in formula (6). Where m is the number of the three current loops corresponding to the three CT numbers, which are 2, 3, and 8 respectively. N is the number of MOV units in each loop.

[0119]

[0120] In the formula, I CTm For CT m The current values ​​of the MOV current loops containing (CT2, CT3, CT8), I m N represents the current value of a single MOV cell. m It's a CT scan. m The number of MOV units in the MOV current loop.

[0121] If I8 is equal to either I2 or I3, the total current measurement is considered accurate. If I8 is not equal to either I2 or I3, but I2 and I3 are equal, the current measurements of both branches are considered accurate, and the sum of the currents of the two branches can be used to replace the measured total MOV current. The low-probability event of two current measurement circuits (including CTs) malfunctioning at the same time is not considered.

[0122] Example 2:

[0123] Based on the same inventive concept, this invention also provides a method for early warning of performance degradation of some valve plates in an MOV, including:

[0124] The primary side MOV total circuit current and MOV branch current are converted into secondary side small currents by the current transformer CT installed in each current circuit of the metal oxide voltage limiter (MOV) in the series compensation complete device. The secondary side small currents are processed by the MOV current acquisition channel installed in the platform measurement box to obtain the MOV total current and MOV branch current.

[0125] The high voltage of the primary MOV is converted into a low voltage of the secondary side by the voltage reduction function of the capacitor voltage divider in the spark gap triggering auxiliary circuit of the series compensation assembly. The low voltage signal of the secondary side is processed by the MOV voltage acquisition channel in the platform measurement box to obtain the MOV voltage.

[0126] The early warning analysis and processing module configured in the series compensation relay protection device provides early warning of the performance degradation of some valve plates in the MOV based on the total MOV current, MOV branch current and MOV voltage, with the consistency of volt-ampere characteristics as the criterion.

[0127] The series compensation assembly includes a series compensation relay protection device.

[0128] Optionally, the early warning analysis and processing module configured in the series compensation relay protection device, based on the total MOV current, MOV branch current, and MOV voltage, and using the consistency of the volt-ampere characteristics as a criterion, provides an early warning of performance degradation of some valve plates in the MOV, including:

[0129] The total current of the MOV and the branch current of the MOV are fitted with the MOV voltage to obtain the current-voltage characteristic curve;

[0130] By comparing the current current-voltage characteristic data with the current-voltage characteristic curve at the time of manufacture, an early warning can be given for the performance degradation of some valve plates in the MOV.

[0131] Optionally, the step of verifying the consistency between the current volt-ampere characteristic data and the volt-ampere characteristic curve at the time of manufacture to achieve early warning of performance degradation of some valve plates in the MOV includes:

[0132] Based on the current current-voltage characteristic data and the current-voltage characteristic curve at the time of manufacture, calculate the current value deviation corresponding to the current value;

[0133] Based on whether the current value deviation meets the set warning conditions, if it does, the performance of the MOV valve plate deteriorates and a warning message is issued; otherwise, the performance of the MOV valve plate does not deteriorate and no warning message is issued.

[0134] Optionally, the acquisition of MOV voltage via a capacitor voltage divider in the spark gap trigger auxiliary circuit of the series compensation assembly and an MOV voltage acquisition channel in the platform measurement box includes:

[0135] The MOV voltage input signal Vin is divided by resistors R1 and R2 in the MOV voltage acquisition channel and then input to the operational amplifier U1 via a side filter composed of resistor R11 and capacitor C11. The output of the operational amplifier U1 is then filtered through the output terminal composed of resistor R12 and capacitor C12 and input to the ADC sampling module to obtain the MOV voltage.

[0136] Specifically, the input signal CT8_I of the MOV total current passes through resistor RL in the MOV total current acquisition channel, then through the signal amplification and conversion stage composed of resistor R22 and operational amplifier U2, and finally through the analog-to-digital conversion stage composed of resistor R21, capacitor C21 and ADC sampling module.

[0137] Example 3

[0138] like Figure 12 As shown, the present invention also provides an electronic device, which may be a computer device, a microcontroller device, a smart mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, processor, and transceiver component are connected via a bus; the memory can be used to store executable programs, and an exemplary executable program may include instructions; the processor is used to execute the instructions stored in the memory. The memory can also be used to store data, which can be accessed and / or modified when instructions are executed.

[0139] The processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, and it is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the storage medium to implement the corresponding method flow or corresponding function, so as to realize the steps of the MOV partial valve plate performance degradation early warning method in the above embodiment.

[0140] Example 4

[0141] Based on the same inventive concept, this invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory). This readable storage medium is a memory device within an electronic device, used to store programs and data. It is understood that the storage medium here can include both built-in storage media within the electronic device and extended storage media supported by the electronic device. The storage medium provides storage space, which stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more executable programs (including program code). It should be noted that the storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. Loading and executing one or more instructions stored in the storage medium by the processor can implement the steps of the MOV partial valve plate performance degradation early warning method in the above embodiments.

[0142] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0143] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0144] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0145] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0146] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A system for early warning of performance degradation of partial valve plates in MOV (Multi-Vehicle Orifice), characterized in that, include: The voltage reduction function of the capacitor voltage divider in the spark gap triggering auxiliary circuit of the series compensation assembly converts the high voltage of the primary side MOV into the low voltage of the secondary side. The low voltage signal of the secondary side is processed by the MOV voltage acquisition channel in the platform measurement box to obtain the MOV voltage. The current transformers (CTs) installed in each current loop of the MOV in the series compensation assembly convert the primary side MOV total loop current and MOV branch current into secondary side small currents. The secondary side small currents are processed by the MOV current acquisition channel installed in the platform measurement box to obtain the MOV total current and MOV branch current. The early warning analysis and processing module is configured in the series compensation relay protection device and is connected to the platform measurement box. It is used to provide early warning of the performance degradation of some valve plates in the MOV based on the total current of the MOV, the branch current of the MOV and the voltage of the MOV, with the consistency of the volt-ampere characteristics as the criterion. The series compensation assembly includes a series compensation relay protection device.

2. The system as described in claim 1, characterized in that, The MOV voltage acquisition channel adopts a two-stage design. The first stage design includes: resistor R1, resistor R2, resistor R11, capacitor C11, and operational amplifier U1. Resistor R1 and resistor R2 are connected in parallel and then connected to one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C11 and the positive input terminal of operational amplifier U1. The other end of capacitor C11 is grounded. The output terminal of operational amplifier U1 is connected to the negative input terminal of operational amplifier U1. The negative power supply of operational amplifier U1 is grounded. The secondary design includes: resistor R12, capacitor C12, and ADC sampling module; One end of resistor R12 is connected to the output of operational amplifier U1, and the other end is connected to one end of capacitor C12 and the input of ADC sampling module, respectively. The other end of capacitor C12 is grounded.

3. The system as described in claim 1, characterized in that, The MOV current acquisition channel adopts a three-level module design. The first-level module includes: a sensor, a resistor RL, and a TVS tube. The sensor is connected in parallel with a resistor RL and a TVS diode, respectively. The second-level module includes: resistors R22, R23, R24, and R25, as well as operational amplifier U2; One end of resistors R22 and R23 is connected to the two ends of the TVS transistor, respectively. The other end of resistor R22 is connected to the positive input terminal of transport amplifier U2 and one end of resistor R24, respectively. The other end of resistor R24 ​​is grounded. The other end of resistor R23 is connected to the negative input terminal of transport amplifier U2 and one end of resistor R25, respectively. The other end of resistor R25 is connected to the output terminal of operational amplifier U2. The negative power supply of operational amplifier U2 is grounded. The third-level module includes: resistor R21, capacitor C21, and ADC sampling module; One end of resistor R21 is connected to the output of operational amplifier U2, and the other end is connected to one end of capacitor C21 and the ADC sampling module. The other end of capacitor C21 is grounded.

4. The system as described in claim 1, characterized in that, The early warning analysis and processing module is specifically used for: The total current, branch current, and voltage of the MOV are processed to obtain the current current-voltage characteristic data; The consistency between the current current-voltage characteristic data and the current-voltage characteristic curve fitted at the factory is judged to achieve early warning of the performance degradation of some valve plates in MOV.

5. The system as described in claim 4, characterized in that, The early warning analysis and processing module performs consistency judgment between the current volt-ampere characteristic data and the volt-ampere characteristic curve fitted at the factory, thereby realizing early warning of performance degradation of some valve plates in the MOV. The specific implementation steps include: Based on the current volt-ampere characteristic data and the volt-ampere characteristic curve at the time of manufacture, calculate the deviation of the total MOV current value and the deviation of the MOV branch current value corresponding to the same MOV voltage value. Determine whether the deviation of the total current value of the MOV or the deviation of the current value of the MOV branch meets the set warning conditions. If it does, the performance of the MOV valve plate deteriorates and a warning message is issued. Otherwise, the performance of the MOV valve plate does not deteriorate and no warning message is issued.

6. The system as described in claim 5, characterized in that, The set warning conditions include: The deviation of the current value corresponding to the same voltage value exceeds the set threshold, and the number of voltage values ​​whose current value deviation exceeds the set threshold is greater than the set number.

7. A method for early warning of performance degradation of partial valve plates in MOVs, characterized in that, include: The primary side MOV total circuit current and MOV branch current are converted into secondary side small currents by the current transformers CT installed in each current loop of the MOV in the series compensation complete device. The secondary side small currents are processed by the MOV current acquisition channel installed in the platform measurement box to obtain the MOV total current and MOV branch current. The high voltage of the primary MOV is converted into a low voltage of the secondary side by the voltage reduction function of the capacitor voltage divider in the spark gap triggering auxiliary circuit of the series compensation assembly. The low voltage signal of the secondary side is processed by the MOV voltage acquisition channel in the platform measurement box to obtain the MOV voltage. The early warning analysis and processing module configured in the series compensation relay protection device provides early warning of the performance degradation of some valve plates in the MOV based on the total MOV current, MOV branch current and MOV voltage, with the consistency of volt-ampere characteristics as the criterion. The series compensation assembly includes a series compensation relay protection device.

8. The method as described in claim 7, characterized in that, The early warning analysis and processing module configured in the series compensation relay protection device provides early warning of performance degradation of some valve plates in the MOV based on the total MOV current, MOV branch current, and MOV voltage, using the consistency of volt-ampere characteristics as a criterion. This includes: The total MOV current, MOV branch current, and MOV voltage are processed to obtain the current volt-ampere characteristic data; By comparing the current current-voltage characteristic data with the current-voltage characteristic curve at the time of manufacture, an early warning can be given for the performance degradation of some valve plates in the MOV.

9. The method as described in claim 8, characterized in that, The step of verifying the consistency between the current volt-ampere characteristic data and the volt-ampere characteristic curve at the time of manufacture, thereby enabling early warning of performance degradation of some valve plates in the MOV, includes: Based on the current volt-ampere characteristic data and the volt-ampere characteristic curve at the time of manufacture, calculate the deviation of the total MOV current value and the deviation of the MOV branch current value corresponding to the same MOV voltage value. Determine whether the deviation of the total current value of the MOV or the deviation of the current value of the MOV branch meets the set warning conditions. If it does, the performance of the MOV valve plate deteriorates and a warning message is issued. Otherwise, the performance of the MOV valve plate does not deteriorate and no warning message is issued.

10. The method as described in claim 7, characterized in that, The method of acquiring MOV voltage via a capacitor voltage divider in the spark gap triggering auxiliary circuit of the series compensation assembly and an MOV voltage acquisition channel in the platform measurement box includes: The MOV voltage input signal Vin is divided by resistors R1 and R2 in the MOV voltage acquisition channel and then input to the operational amplifier U1 via a side filter composed of resistor R11 and capacitor C11. The output of the operational amplifier U1 is then filtered through the output terminal composed of resistor R12 and capacitor C12 and input to the ADC sampling module to obtain the MOV voltage.

11. An electronic device, characterized in that, include: At least one processor and memory; The memory and processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a method for early warning of performance degradation of MOV partial valve plates as described in any one of claims 7 to 10 is implemented.

12. A readable storage medium, characterized in that, It contains an execution program, which, when executed, implements a method for early warning of performance degradation of MOV partial valve plates as described in any one of claims 7 to 10.

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