Thyristor runaway conduction detection control method and system for dynamic reactive compensation device

Abstract

This invention discloses a thyristor uncontrolled conduction detection and control method and system for a dynamic reactive power compensation device, relating to the field of reactive power compensation technology. The method includes: when there is no trigger command, sampling the gate-cathode voltage of the thyristor and comparing it with the forward voltage drop of the gate-cathode PN junction to determine if a trigger signal is present; when there is no trigger signal, sampling the anode-cathode voltage of the thyristor, calculating the anode-cathode voltage change, and determining the thyristor uncontrolled conduction type based on the comparison of the voltage change with a set voltage threshold, the comparison of the anode-cathode voltage with the on-state voltage drop, and their respective durations; and issuing a corresponding switching command based on the thyristor uncontrolled conduction type to complete the switching control of the capacitor-reactor group. This method not only quickly detects thyristor uncontrolled conduction and determines the type of uncontrolled conduction, but also rapidly controls it, maintaining three-phase current balance and avoiding damage to equipment and impact on the power grid caused by intermittent inrush current.

Description

Technical Field

[0001] This invention relates to the field of reactive power compensation technology, and in particular to a thyristor uncontrolled conduction detection and control method and system for a dynamic reactive power compensation device. Background Technology

[0002] Thyristor-switched dynamic reactive power compensation devices are widely used in applications with large and rapidly changing reactive power fluctuations due to their advantages such as fast response speed and no inrush current during switching. However, in recent years, with the widespread application of thyristor-switched dynamic reactive power compensation devices, uncontrolled conduction of thyristors due to various reasons has become increasingly common. Common examples include uncontrolled conduction caused by a drop in forward blocking voltage and conduction due to breakdown.

[0003] Currently, in most thyristor-switched dynamic reactive power compensation devices, when a thyristor experiences uncontrolled conduction, the controller first disconnects all connected capacitor banks. However, the uncontrolled thyristor is uncontrollable and cannot be turned off. In particular, uncontrolled conduction caused by a drop in the thyristor's forward blocking voltage not only damages other components in the equipment but also has a serious impact on the power grid, while also causing three-phase current imbalance. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a thyristor uncontrolled conduction detection and control method and system for a dynamic reactive power compensation device. This method not only rapidly detects thyristor uncontrolled conduction and determines the type of uncontrolled conduction, but also quickly implements control measures to maintain three-phase current balance and prevent intermittent inrush current from damaging the equipment and impacting the power grid.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a thyristor uncontrolled conduction detection and control method for a dynamic reactive power compensation device, comprising:

[0007] When there is no trigger command, the gate-cathode voltage of the thyristor is sampled and compared with the forward voltage drop of the gate-cathode forward PN junction to determine whether there is a trigger signal.

[0008] When there is no trigger signal, the voltage between the anode and cathode of the thyristor is sampled, the change in voltage between the anode and cathode is calculated, and the type of uncontrolled conduction of the thyristor is determined based on the comparison between the voltage change and the set voltage threshold, the comparison between the voltage between the anode and cathode and the on-state voltage drop, and the duration of each.

[0009] Based on the type of thyristor uncontrolled conduction, a corresponding switching command is issued to complete the switching control of the capacitor-reactor group.

[0010] As an alternative implementation, the process for determining whether there is a trigger signal includes: if the gate-cathode voltage is less than the gate-cathode forward PN junction voltage drop, it indicates that the thyristor has no trigger signal.

[0011] As an alternative implementation, the process of determining the uncontrolled conduction type of the thyristor includes: if the anode-cathode voltage is less than or equal to the on-state voltage drop and the duration is greater than or equal to a set first time period, it indicates that the thyristor is always conducting and has no recovery blocking capability, and it is determined that the thyristor has broken down and conducted.

[0012] As an alternative implementation, the switching control process for the capacitor-reactor group includes: for the capacitor branch where the thyristor has broken down and conducted, triggering the non-faulty thyristor of the capacitor branch to conduct, switching on the non-faulty phase capacitor-reactor group, and maintaining the three-phase current balance.

[0013] As an alternative implementation method, the process for determining the type of uncontrolled thyristor conduction includes:

[0014] If the change in anode-cathode voltage is greater than the set voltage threshold, the anode-cathode voltage of the previous sample is greater than the on-state voltage drop, the anode-cathode voltage of the current sample is less than or equal to the on-state voltage drop, and the anode-cathode voltage of subsequent samples is still less than or equal to the on-state voltage drop and continues for a second time period, it indicates that the thyristor suddenly turns on from the blocking state. If this occurs repeatedly within at least a set number of power frequency cycles, it is determined that the thyristor has lost control and turned on due to a drop in the forward blocking voltage, and this is an intermittent loss of control. The anode-cathode voltage of the previous sample during the drop process is the value after the thyristor's forward blocking voltage drops.

[0015] As an alternative implementation, the switching control process for the capacitor-reactor group includes: for the capacitor branch where the thyristor has run out of control and turned on due to the drop in forward blocking voltage, triggering all thyristors in the capacitor branch to turn on, putting all phase capacitor-reactor groups into operation, and re-triggering the thyristors that have run out of control and turned on due to the drop in blocking voltage, so that the branch current changes from inrush current to steady-state rated current.

[0016] Secondly, the present invention provides a thyristor uncontrolled conduction detection and control system for a dynamic reactive power compensation device, comprising:

[0017] The first detection module is configured to sample the gate-cathode voltage of the thyristor when there is no trigger command, and compare it with the forward voltage drop of the gate-cathode forward PN junction to determine whether there is a trigger signal.

[0018] The second detection module is configured to sample the anode-cathode voltage of the thyristor when there is no trigger signal, calculate the change in anode-cathode voltage, and determine the type of uncontrolled conduction of the thyristor based on the comparison results of the voltage change with the set voltage threshold, the comparison results of the anode-cathode voltage with the on-state voltage drop, and the duration of each.

[0019] The control module is configured to issue corresponding switching commands based on the thyristor uncontrolled conduction type to complete the switching control of the capacitor-reactor group.

[0020] Thirdly, the present invention provides an electronic device including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0021] Fourthly, the present invention provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in the first aspect.

[0022] Fifthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the method described in the first aspect.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention proposes a method and system for detecting and controlling thyristor uncontrolled conduction in a dynamic reactive power compensation device. This system can not only quickly detect thyristor uncontrolled conduction and determine the type of uncontrolled conduction, but also rapidly implement control. For breakdown conduction, capacitor banks in other phases of the faulty thyristor branch are activated to maintain three-phase current balance. For uncontrolled conduction caused by a drop in the forward blocking voltage of the thyristor, the faulty thyristor and other phase thyristors in the same circuit are triggered again, causing intermittent inrush current to enter the steady-state rated current of the faulty thyristor branch. This avoids damage to equipment caused by intermittent inrush current (such as overcurrent breakdown, bulging, or explosion of capacitors; magnetic saturation and coil overheating and burnout of reactors; PN junction breakdown and thermal damage of thyristors, etc.) and impact on the power grid (such as voltage waveform distortion and drops, even causing protection tripping and shutdown of other power grid equipment, causing grid resonance, and further expanding the scope of the fault's impact).

[0025] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a flowchart of the thyristor uncontrolled conduction detection and control method for the dynamic reactive power compensation device provided in Embodiment 1 of the present invention;

[0028] Figure 2 The electrical schematic diagram provided for Embodiment 1 of the present invention;

[0029] Figure 3 This is a schematic diagram of the internal structure of the thyristor provided in Embodiment 1 of the present invention;

[0030] Figure 4 This is a flowchart illustrating the thyristor uncontrolled conduction detection and control principle provided in Embodiment 1 of the present invention.

[0031] Figure 5 This is a waveform diagram of uncontrolled conduction inrush current caused by a drop in thyristor blocking voltage, provided in Embodiment 1 of the present invention.

[0032] Figure 6 This is a waveform diagram of thyristor blocking voltage drop causing uncontrolled conduction and re-triggering provided in Embodiment 1 of the present invention;

[0033] Figure 7 The waveform diagram of thyristor blocking voltage drop causing uncontrolled conduction and re-triggering provided in Embodiment 1 of the present invention is shown. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0036] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0038] As described in the background section, with the widespread application of thyristor-switched dynamic reactive power compensation devices, thyristor uncontrolled conduction frequently occurs due to various reasons, including the following:

[0039] One type of fault is uncontrolled conduction caused by a drop in the forward blocking voltage. The characteristic of this type of fault is that the thyristor is not completely broken down; it can still maintain its blocking characteristics at low voltage, only the blocking voltage is lowered, equivalent to a voltage drop. For example, aging of the internal silicon wafer caused by prolonged high-temperature operation of the thyristor, or the thyristor module being exposed to humid environments where moisture and impurities can easily seep into the internal silicon wafer, leading to increased leakage current and decreased insulation performance, will all cause a drop in the thyristor's forward blocking voltage, resulting in uncontrolled conduction.

[0040] Second, breakdown conduction. Due to voltage spikes caused by the load (such as commutation overvoltage), or operational overvoltage, lightning overvoltage, and insufficient capacity of the conventionally configured absorption circuit, the thyristor may experience complete overvoltage breakdown and conduction. This can also be caused by high harmonic current content in the compensation branch, or by excessive current flowing through the thyristor due to circuit faults. For ease of maintenance, the protection circuit breaker is usually connected outside the delta connection (the protection value is typically selected as 1.5 times the rated current outside the delta). The overcurrent of a fault in one phase inside the delta generally does not reach the circuit breaker's protection action value. In this case, the overcurrent will cause the thyristor junction temperature to rise. When the heat exceeds the power dissipation, the thyristor PN junction will experience overcurrent breakdown and conduction.

[0041] The hazards of uncontrolled thyristor conduction include the following:

[0042] First, there is the hazard of uncontrolled conduction caused by a drop in forward blocking voltage. When the forward blocking voltage of a thyristor is lower than the maximum voltage it can withstand in the circuit, the thyristor will conduct on its own without the control of the trigger signal, generating an inrush current several times its rated current. When the current flowing through the thyristor drops to zero, the thyristor will naturally turn off. This cycle of self-conduction and self-turning occurs repeatedly, resulting in an intermittent and continuous inrush current. Long-term accumulation of this inrush current can easily cause capacitor overcurrent breakdown, bulging, or explosion; cause thyristor PN junction breakdown and thermal damage; and cause series reactors to experience magnetic saturation due to instantaneous large currents, leading to coil overheating and accelerated insulation aging, potentially causing reactor burnout over long-term operation. Inrush current can also be injected into the power grid, generating impulse voltage, causing voltage waveform distortion and drops, and even causing protection tripping and shutdown of other equipment in the power grid. In severe cases, it can even cause grid resonance, further expanding the scope of the fault's impact.

[0043] Second, there is the hazard of breakdown and conduction. Complete overvoltage breakdown and overcurrent breakdown of thyristors are irreversible. The thyristor loses its blocking ability and will continue to conduct. The resulting inrush current usually decays and recovers to the normal rated current waveform within a few milliseconds. It will not have a long-term impact on the equipment. Compared with the hazard of uncontrolled conduction caused by the drop in forward blocking voltage, it will only cause three-phase current imbalance.

[0044] Currently, most thyristor-switched dynamic reactive power compensation devices, when experiencing uncontrolled thyristor conduction, first disconnect all connected capacitor banks. However, the uncontrolled thyristor is uncontrollable and cannot be turned off. In particular, the uncontrolled conduction caused by the drop in the thyristor's forward blocking voltage not only damages other components in the equipment but also has a serious impact on the power grid, while causing three-phase current imbalance.

[0045] Therefore, this invention proposes a thyristor uncontrolled conduction detection and control method for a dynamic reactive power compensation device. This method not only quickly detects thyristor uncontrolled conduction and determines the type of uncontrolled conduction, but also rapidly implements control. For breakdown conduction, capacitor banks in other phases of the faulty thyristor branch are activated to maintain three-phase current balance. For uncontrolled conduction caused by a drop in the forward blocking voltage of the thyristor, the faulty thyristor and other thyristors in the same phase are triggered again, causing intermittent inrush current to enter the steady-state rated current of the faulty thyristor branch, thus avoiding damage to the equipment and impact on the power grid caused by intermittent inrush current.

[0046] Example 1

[0047] This embodiment provides a thyristor uncontrolled conduction detection and control method for a dynamic reactive power compensation device, such as... Figure 1 As shown, it includes:

[0048] When there is no trigger command, the gate-cathode voltage of the thyristor is sampled and compared with the forward voltage drop of the gate-cathode forward PN junction to determine whether there is a trigger signal.

[0049] When there is no trigger signal, the voltage between the anode and cathode of the thyristor is sampled, the change in voltage between the anode and cathode is calculated, and the type of uncontrolled conduction of the thyristor is determined based on the comparison between the voltage change and the set voltage threshold, the comparison between the voltage between the anode and cathode and the on-state voltage drop, and the duration of each.

[0050] Based on the type of thyristor uncontrolled conduction, a corresponding switching command is issued to complete the switching control of the capacitor-reactor group.

[0051] like Figure 2 The diagram shows the electrical schematic of a dynamic reactive power compensation device with thyristor fail-control conduction detection and control, including a control unit, a sampling current transformer, a thyristor voltage detection module, a compensation current transformer, and a capacitor-reactor group. Figure 3 The diagram shown is a schematic of the internal structure of a thyristor.

[0052] The sampling current transformer samples the instantaneous values ​​of system voltage and current. The control unit calculates the system reactive power and required compensation capacity in real time. According to the preset switching logic, it quickly judges and issues the corresponding switching command to complete the switching control of the capacitor and reactor group, and realizes dynamic tracking compensation of load reactive power.

[0053] The control unit incorporates a zero-transition process moment detection and control system to ensure that the capacitor-reactor group is switched on at the zero-transition instant and switched off naturally at the zero-current moment. The switching process is free of transient disturbances, avoiding inrush current impacts and operational overvoltages. It also effectively reduces the electrical stress impact on the thyristors and capacitors during the switching process, improving equipment reliability and service life.

[0054] The thyristor voltage detection module detects the gate-cathode (GK) voltage and anode-cathode (AK) voltage of the thyristor in real time. Based on the detection results and logical judgment, the control unit comprehensively determines the thyristor's uncontrolled conduction type and issues corresponding control commands according to the control logic to complete the detection and control of the uncontrolled thyristor.

[0055] The following is combined Figure 4 The process shown below provides a detailed explanation of the method in this embodiment.

[0056] (1) Determine whether the device is powered on.

[0057] The control unit processes the sampled three-phase voltages U1, U2, and U3 to obtain the effective values ​​U of the three-phase voltages. r1 U r2 U r3The effective value is compared with the set voltage U. S Compare;

[0058] If U r1 >U S AndU r2 >U S AndU r3 >U S If the device is powered on, the following steps can be performed; otherwise, the current detection and control process ends.

[0059] Among them, U S It can be set to 0.85 times the system's rated voltage. For example, for a 400V system, U S =0.85*400=340V.

[0060] (2) Determine if there is a trigger command in the capacitor branch.

[0061] If the device is powered on, the control unit will initiate the detection and judgment of the thyristor gate-cathode (GK) voltage in the capacitor branch without trigger command, based on the issued trigger command signal.

[0062] (3) Determine whether there is trigger signal interference in the capacitor branch.

[0063] The thyristor voltage detection module acquires the gate-cathode (GK) voltage U of the thyristor in real time. GK Each power frequency cycle samples 256 points, performs isolation filtering, and then transmits the data to the control unit.

[0064] Compare U by the control unit GK and gate-cathode forward PN junction on-state voltage drop U G The size of U GK <U G If the signal is positive, it indicates that the thyristor has no trigger signal, and the detection and judgment of the thyristor anode-cathode (AK) terminal voltage can continue; otherwise, the current detection and control process ends.

[0065] Among them, U G It can be set to 0.3V because if there is no trigger signal, the gate-cathode PN junction is cut off, and the measured thyristor GK terminal voltage U GK ≈0V; if there is a trigger signal, the forward voltage drop of the gate-cathode forward PN junction is generally between 0.6 and 1.0V.

[0066] (4) Determine the type of uncontrolled conduction of the thyristor.

[0067] The voltage detection and judgment at the thyristor anode-cathode (AK) terminals of the capacitor branch without a trigger signal are performed as follows:

[0068] (4-1) The thyristor voltage detection module acquires the voltage U at the anode-cathode (AK) terminals of the thyristor in real time. AK Each power frequency cycle samples 256 points, performs isolation filtering, and then transmits the data to the control unit.

[0069] The control unit calculates the difference ΔU between two adjacent sampled voltages. AK (△U) AK =Previous sampling voltage U AK1 -Current sampling voltage U AK2 ).

[0070] Compare △U AK And set the voltage threshold value ΔU; where ΔU can be set to 20V;

[0071] Compare U AK and on-state pressure drop U T The size of U; where U T It can be set to 2.0V, U T It is the voltage value at the AK terminal after the thyristor is triggered and turned on, which is generally between 0.8 and 2.0V.

[0072] (4-2) If U is always present AK ≤U T If the duration is greater than or equal to the set time t1 (e.g., 2s), it indicates that the voltage at the AK terminal of the thyristor is less than or equal to the on-state voltage drop when there is no trigger signal. This means that the thyristor is always conducting and has no recovery blocking capability. It is determined that the thyristor has broken down and is conducting, and the control will issue a thyristor breakdown and conduction alarm for this branch to remind the staff to check the fault.

[0073] (4-3) If △U appears AK >△U (and at this time U AK1 >U T And U AK2 ≤U T ), and subsequent U AK ≤U T And continuously set a time period t2~t3 (e.g., 3~10ms) to indicate that the voltage U at the AK terminal of the thyristor is constant when there is no trigger signal. AK The variation is large, from high voltage (U AK1 >U T The pressure suddenly drops to the through-state pressure drop (U). AK2 ≤U T ) and below, while low voltage (U AK ≤U T This lasts for 3~10ms. This indicates that the thyristor suddenly turns on from the blocking state, and the sampling voltage U before the drop process... AK1 This is the value after the forward blocking voltage of the thyristor decreases.

[0074] Meanwhile, if this phenomenon repeats within a set number of power frequency cycles (e.g., 5 power frequency cycles), it indicates that the process is repeatable and intermittent, confirming that the thyristor is intermittently uncontrolled.

[0075] like Figure 5 The figure shows the inrush current waveform caused by the drop in the forward blocking voltage of the thyristor. The red curve is the AC grid line voltage, the yellow curve is the AC grid phase-to-phase current (AB), and the purple curve is the voltage at the AK terminal. At this time, the blocking voltage of the thyristor drops to about 270V.

[0076] Figure 5 The image shows waveforms from an oscilloscope test. Channel 1 (yellow) represents the AC mains current between phases AB, with 100A indicating 100A / division vertically. Channel 3 (purple) represents the voltage at terminal AK, with 200V indicating 200V / division vertically. Channel 4 (red) represents the AC mains line voltage, with 250V indicating 250V / division vertically. The time 5.000ms indicates 5.000ms / division horizontally.

[0077] The control unit records the value of the thyristor's forward blocking voltage after it drops, and issues an alarm for the thyristor's forward blocking voltage drop in this branch, reminding staff to troubleshoot the fault.

[0078] (5) Control according to the type of thyristor uncontrolled conduction.

[0079] At the same time as the control unit issues an alarm, it also issues a trigger command to the capacitor branch where the thyristor has malfunctioned and turned on.

[0080] For the capacitor branch where the thyristor breaks down and conducts in step (4-1), a trigger command is issued to the capacitor branch to trigger the non-faulty thyristor of the capacitor branch to conduct, and the non-faulty phase capacitor reactor group is put into operation, thereby maintaining the three-phase current balance.

[0081] For the capacitor branch that was turned on by the thyristor's forward blocking voltage drop in step (4-2), a trigger command is issued to this capacitor branch to trigger all thyristors in the capacitor branch to turn on, and all phase capacitor reactor groups are engaged. Figures 6-7 As shown, yellow, green, and red represent the three-phase currents, where... Figure 6 The image shows the waveforms from an oscilloscope test. At the top of the image, channel 1 is yellow (phase A current), channel 2 is green (phase B current), and channel 4 is red (phase C current). 100A indicates 100A / division vertically, and 500.0ms indicates 500.0ms / division horizontally. Figure 7This is a waveform diagram from an oscilloscope test. At the top of the image, channel 1 (yellow) represents phase A current, channel 2 (green) represents phase B current, and channel 4 (red) represents phase C current. 100A indicates 100A per division vertically, and 20.00ms indicates 20.00ms per division horizontally. Re-triggering the thyristor that was blocking the voltage drop causes it to turn on again, and the branch current changes from inrush current to steady-state rated current, avoiding damage to equipment and impact on the power grid caused by intermittent inrush current.

[0082] The method described in this embodiment can not only quickly detect thyristor uncontrolled conduction and determine the type of uncontrolled conduction, but also quickly implement control. For breakdown conduction, capacitor banks in other phases of the faulty thyristor branch are activated to maintain three-phase current balance. For uncontrolled conduction caused by a drop in the forward blocking voltage of the thyristor, the faulty thyristor and other thyristors in the same phase are triggered again, causing intermittent inrush current to enter the steady-state rated current of the faulty thyristor branch, thus avoiding damage to equipment and impact on the power grid caused by intermittent inrush current. Damage to equipment caused by intermittent inrush current includes overcurrent breakdown, bulging, or explosion of capacitors; magnetic saturation and coil overheating and burnout of reactors; and PN junction breakdown and thermal damage of thyristors. The impact of intermittent inrush current on the power grid includes voltage waveform distortion and drops, and may even cause protection tripping and shutdown of other equipment in the power grid. In severe cases, it can cause grid resonance, further expanding the scope of the fault's impact.

[0083] Example 2

[0084] This embodiment provides a thyristor uncontrolled conduction detection and control system for a dynamic reactive power compensation device, including:

[0085] The first detection module is configured to sample the gate-cathode voltage of the thyristor when there is no trigger command, and compare it with the forward voltage drop of the gate-cathode forward PN junction to determine whether there is a trigger signal.

[0086] The second detection module is configured to sample the anode-cathode voltage of the thyristor when there is no trigger signal, calculate the change in anode-cathode voltage, and determine the type of uncontrolled conduction of the thyristor based on the comparison results of the voltage change with the set voltage threshold, the comparison results of the anode-cathode voltage with the on-state voltage drop, and the duration of each.

[0087] The control module is configured to issue corresponding switching commands based on the thyristor uncontrolled conduction type to complete the switching control of the capacitor-reactor group.

[0088] It should be noted that the above modules correspond to the steps described in Embodiment 1, and the examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the content disclosed in Embodiment 1. It should also be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0089] In further embodiments, the following is also provided:

[0090] An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in Embodiment 1. For brevity, further details are omitted here.

[0091] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0092] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0093] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in Embodiment 1.

[0094] The method in Example 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor. The software modules can reside in readily available storage media in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, a detailed description is not provided here.

[0095] A computer program product includes a computer program that, when executed by a processor, implements the method described in Embodiment 1.

[0096] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, which execute in a device on a target real or virtual processor to perform the processes / methods described above. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided among program modules as needed. The machine-executable instructions for the program modules can execute within a local or distributed device. In a distributed device, the program modules can reside in both local and remote storage media.

[0097] The computer program code used to implement the methods of the present invention may be written in one or more programming languages. This computer program code may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the computer or other programmable data processing device, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a computer, partially on a computer, as a stand-alone software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server.

[0098] In the context of this invention, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like. Examples of signals may include electrical, optical, radio, sound, or other forms of propagation signals, such as carrier waves, infrared signals, etc.

[0099] Those skilled in the art will recognize that the units and algorithm steps described in connection with the various examples of this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0100] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for detecting and controlling the uncontrolled conduction of thyristors in a dynamic reactive power compensation device, characterized in that, include: When there is no trigger command, the gate-cathode voltage of the thyristor is sampled and compared with the forward voltage drop of the gate-cathode forward PN junction to determine whether there is a trigger signal. When there is no trigger signal, the voltage between the anode and cathode of the thyristor is sampled, the change in voltage between the anode and cathode is calculated, and the type of uncontrolled conduction of the thyristor is determined based on the comparison between the voltage change and the set voltage threshold, the comparison between the voltage between the anode and cathode and the on-state voltage drop, and the duration of each. The process of determining the type of uncontrolled conduction of a thyristor includes: If the anode-cathode voltage is less than or equal to the on-state voltage drop and the duration is greater than or equal to the set first time period, it indicates that the thyristor is always conducting and has no recovery blocking capability, and it is determined that the thyristor has broken down and is conducting. If the change in anode-cathode voltage is greater than the set voltage threshold, the anode-cathode voltage of the previous sample is greater than the on-state voltage drop, the anode-cathode voltage of the current sample is less than or equal to the on-state voltage drop, and the anode-cathode voltage of subsequent samples is still less than or equal to the on-state voltage drop and continues for a second time period, it indicates that the thyristor suddenly turns on from the blocking state. If this happens repeatedly within at least a set number of power frequency cycles, it is determined that the uncontrolled conduction of the thyristor due to the drop in forward blocking voltage is an intermittent uncontrolled conduction. The anode-cathode voltage of the previous sample during the drop process is the value after the drop in the forward blocking voltage of the thyristor. Based on the type of thyristor uncontrolled conduction, a corresponding switching command is issued to complete the switching control of the capacitor-reactor group.

2. The thyristor uncontrolled conduction detection and control method for the dynamic reactive power compensation device as described in claim 1, characterized in that, The process of determining whether there is a trigger signal includes: if the gate-cathode voltage is less than the gate-cathode forward PN junction voltage drop, it means that the thyristor has no trigger signal.

3. The thyristor uncontrolled conduction detection and control method for the dynamic reactive power compensation device as described in claim 1, characterized in that, The switching control process for the capacitor-reactor bank includes: for the capacitor branch where the thyristor has broken down and is conducting, triggering the non-faulty thyristor of that capacitor branch to conduct, switching on the non-faulty phase capacitor-reactor bank, and maintaining the three-phase current balance.

4. The thyristor uncontrolled conduction detection and control method for the dynamic reactive power compensation device as described in claim 1, characterized in that, The switching control process for the capacitor-reactor group includes: for the capacitor branch where the thyristor has run out of control and turned on due to the drop in forward blocking voltage, triggering all thyristors in the capacitor branch to turn on, putting all phase capacitor-reactor groups into operation, and re-triggering the thyristors that have run out of control and turned on due to the drop in blocking voltage, so that the branch current changes from inrush current to steady-state rated current.

5. A thyristor fail-control conduction detection and control system for a dynamic reactive power compensation device, characterized in that, include: The first detection module is configured to sample the gate-cathode voltage of the thyristor when there is no trigger command, and compare it with the forward voltage drop of the gate-cathode forward PN junction to determine whether there is a trigger signal. The second detection module is configured to sample the anode-cathode voltage of the thyristor when there is no trigger signal, calculate the change in anode-cathode voltage, and determine the type of uncontrolled conduction of the thyristor based on the comparison results of the voltage change with the set voltage threshold, the comparison results of the anode-cathode voltage with the on-state voltage drop, and the duration of each. The process of determining the type of uncontrolled conduction of a thyristor includes: If the anode-cathode voltage is less than or equal to the on-state voltage drop and the duration is greater than or equal to the set first time period, it indicates that the thyristor is always conducting and has no recovery blocking capability, and it is determined that the thyristor has broken down and is conducting. If the change in anode-cathode voltage is greater than the set voltage threshold, the anode-cathode voltage of the previous sample is greater than the on-state voltage drop, the anode-cathode voltage of the current sample is less than or equal to the on-state voltage drop, and the anode-cathode voltage of subsequent samples is still less than or equal to the on-state voltage drop and continues for a second time period, it indicates that the thyristor suddenly turns on from the blocking state. If this happens repeatedly within at least a set number of power frequency cycles, it is determined that the uncontrolled conduction of the thyristor due to the drop in forward blocking voltage is an intermittent uncontrolled conduction. The anode-cathode voltage of the previous sample during the drop process is the value after the drop in the forward blocking voltage of the thyristor. The control module is configured to issue corresponding switching commands based on the thyristor uncontrolled conduction type to complete the switching control of the capacitor-reactor group.

6. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the method according to any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, perform the method described in any one of claims 1-4.

8. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements the method described in any one of claims 1-4.

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