Method for detecting bypass protection thyristor of power module of flexible direct current converter valve and related equipment

Abstract

The invention discloses a flexible DC converter valve power module bypass protection thyristor detection method and related equipment, a to-be-detected thyristor is selected from a plurality of bypass protection thyristors to access a flexible DC converter valve power module, AC voltage and AC current are increased according to a first preset gradient, and a volt-ampere characteristic curve is constructed; performing leakage current detection according to the volt-ampere characteristic curve to generate a first detection result; if the first detection result is passing, small current detection is executed, and a second detection result is generated; if the second detection result is passing, large current detection is executed, and a third detection result is generated; and if the third detection result is passing, determining that each bypass protection thyristor passes the detection. Thyristors put into engineering application are ensured to pass strict multi-stage tests, and the power module fault risk during operation of the converter valve is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of thyristor detection, and in particular to a detection method and related equipment for a bypass protection thyristor of a flexible DC converter valve power module. Background Art

[0002] The intermittent and volatile nature of renewable energy sources places higher demands on the transmission capacity, stability, and flexibility of power systems. Flexible DC transmission technology, with its advantages in enabling asynchronous grid interconnection, rapid and flexible power regulation, and power quality control, has become a core transmission technology for building new power systems. It is crucial for ensuring the efficient integration of renewable energy and the stable operation of power systems.

[0003] As a key component of flexible DC transmission systems, flexible DC converter valves typically utilize a modular multilevel topology. Within each power module, bypass protection thyristors are a crucial component of most technology approaches. Currently, the design of power modules for flexible DC converter valves primarily utilizes three types: conventional forward shunt thyristors, bidirectional breakdown thyristors, and bypass protection thyristors with both forward current flow and reverse breakdown capabilities. These different thyristor types perform specific protective functions within the power module, and their performance directly impacts the operation of the converter valve and, ultimately, the entire flexible DC transmission system.

[0004] However, due to inconsistent quality control of bypass protection thyristors, the breakover voltage deviation of the bypass protection thyristors is large, increasing the risk of failure of the flexible DC transmission system. Summary of the Invention

[0005] The present invention provides a detection method and related equipment for the bypass protection thyristors of the power module of a flexible direct current converter valve, which solves the technical problem that the bypass protection thyristors have large breakover voltage deviations due to inconsistent quality control, thereby increasing the risk of failure in the flexible direct current transmission system.

[0006] The present invention provides a method for detecting a bypass protection thyristor of a flexible DC converter valve power module, comprising:

[0007] Selecting a thyristor to be tested from a plurality of bypass protection thyristors and connecting it to a flexible DC converter valve power module, and increasing the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve;

[0008] Perform leakage current detection according to the volt-ampere characteristic curve to generate a first detection result;

[0009] If the first detection result is passed, a low current detection is performed to generate a second detection result;

[0010] If the second detection result is passed, performing a high current detection to generate a third detection result;

[0011] If the third detection result is passed, it is determined that each of the bypass protection thyristors has passed the test.

[0012] Optionally, performing leakage current detection according to the volt-ampere characteristic curve to generate a first detection result includes:

[0013] Comparing the volt-ampere characteristic curve with a preset leakage current curve to calculate the curve similarity;

[0014] If the curve similarity is greater than or equal to a preset similarity threshold, the first detection result is determined to be passed;

[0015] If the curve similarity is less than a preset similarity threshold, the first detection result is determined to be failed.

[0016] Optionally, if the first detection result is a pass, performing a low current detection to generate a second detection result includes:

[0017] If the first detection result is passed, increasing the AC voltage and the AC current according to a second preset gradient, and detecting the voltage across the thyristor to be tested;

[0018] When the voltages at both ends return to zero, the AC voltage and AC current at the current moment are maintained and the capacitor voltage of the flexible DC converter valve power module is monitored in real time;

[0019] If the current holding time of the flexible DC converter valve power module is not less than the preset holding threshold and the capacitor voltage drops to zero, the current of the thyristor to be tested is disconnected;

[0020] If the resistance of the thyristor to be tested is in a high-resistance state, determining that the second test result is passed;

[0021] If the current holding time of the flexible DC converter valve power module is less than the preset holding threshold, or the capacitor voltage does not drop to zero, or the resistance of the thyristor to be tested is not in a high-resistance state, the second detection result is determined to be failed.

[0022] Optionally, if the second detection result is a pass, performing a high current detection to generate a third detection result includes:

[0023] If the second detection result is passed, increasing the AC voltage and the AC current according to a third preset gradient, and monitoring the module voltage of the flexible DC converter valve power module;

[0024] When the thyristor to be tested is broken down and the module voltage decays to zero, the current of the thyristor to be tested is disconnected;

[0025] If the resistance of the thyristor to be tested is within a preset resistance range, determining that the third test result is passed;

[0026] If the thyristor to be tested is not broken down, or the module voltage is not decayed to zero, or the resistance of the thyristor to be tested is not within a preset resistance range, the third test result is determined to be failed.

[0027] Optionally, the method further includes:

[0028] If the first test result, the second test result or the third test result is failure, it is determined that the thyristor to be tested has failed the test;

[0029] Selecting a new thyristor to be tested from the remaining plurality of bypass protection thyristors, and connecting the new thyristor to be tested to the flexible DC converter valve power module;

[0030] Jump to the step of increasing the AC voltage and AC current according to the first preset gradient to construct a volt-ampere characteristic curve;

[0031] If the number of times that the thyristor to be tested is determined to have failed the test is greater than a preset determination threshold, it is determined that each of the bypass protection thyristors has failed the test.

[0032] The present invention also provides a detection device for a bypass protection thyristor of a flexible DC converter valve power module, comprising:

[0033] a curve construction module, configured to select a thyristor to be tested from a plurality of bypass protection thyristors, connect the thyristor to the flexible DC converter valve power module, and increase the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve;

[0034] a leakage current detection module, configured to perform leakage current detection according to the volt-ampere characteristic curve and generate a first detection result;

[0035] A low current detection module, configured to perform a low current detection and generate a second detection result if the first detection result is a pass;

[0036] A high current detection module, configured to perform high current detection and generate a third detection result if the second detection result is a pass;

[0037] The detection pass determination module is configured to determine whether each of the bypass protection thyristors has passed the detection if the third detection result is a pass.

[0038] Optionally, the leakage current detection module is specifically used to:

[0039] Comparing the volt-ampere characteristic curve with a preset leakage current curve to calculate the curve similarity;

[0040] If the curve similarity is greater than or equal to a preset similarity threshold, the first detection result is determined to be passed;

[0041] If the curve similarity is less than a preset similarity threshold, the first detection result is determined to be failed.

[0042] Optionally, the low current detection module is specifically used to:

[0043] If the first detection result is passed, increasing the AC voltage and the AC current according to a second preset gradient, and detecting the voltage across the thyristor to be tested;

[0044] When the voltages at both ends return to zero, the AC voltage and AC current at the current moment are maintained and the capacitor voltage of the flexible DC converter valve power module is monitored in real time;

[0045] If the current holding time of the flexible DC converter valve power module is not less than the preset holding threshold and the capacitor voltage drops to zero, the current of the thyristor to be tested is disconnected;

[0046] If the resistance of the thyristor to be tested is in a high-resistance state, determining that the second test result is passed;

[0047] If the current holding time of the flexible DC converter valve power module is less than the preset holding threshold, or the capacitor voltage does not drop to zero, or the resistance of the thyristor to be tested is not in a high-resistance state, the second detection result is determined to be failed.

[0048] Optionally, the high current detection module is specifically used to:

[0049] If the second detection result is passed, increasing the AC voltage and the AC current according to a third preset gradient, and monitoring the module voltage of the flexible DC converter valve power module;

[0050] When the thyristor to be tested is broken down and the module voltage decays to zero, the current of the thyristor to be tested is disconnected;

[0051] If the resistance of the thyristor to be tested is within a preset resistance range, determining that the third test result is passed;

[0052] If the thyristor to be tested is not broken down, or the module voltage is not decayed to zero, or the resistance of the thyristor to be tested is not within a preset resistance range, the third test result is determined to be failed.

[0053] Optionally, the device further includes a recheck module, specifically configured to:

[0054] If the first test result, the second test result or the third test result is failure, it is determined that the thyristor to be tested has failed the test;

[0055] Selecting a new thyristor to be tested from the remaining plurality of bypass protection thyristors, and connecting the new thyristor to be tested to the flexible DC converter valve power module;

[0056] Jump to the step of increasing the AC voltage and AC current according to the first preset gradient to construct a volt-ampere characteristic curve;

[0057] If the number of times that the thyristor to be tested is determined to have failed the test is greater than a preset determination threshold, it is determined that each of the bypass protection thyristors has failed the test.

[0058] It can be seen from the above technical solutions that the present invention has the following advantages:

[0059] The present invention selects a thyristor to be tested from multiple bypass protection thyristors and connects it to the flexible DC converter valve power module. The AC voltage and AC current are increased according to a first preset gradient to construct a volt-ampere characteristic curve. Leakage current detection is performed according to the volt-ampere characteristic curve to generate a first test result. If the first test result is a pass, a low current test is performed to generate a second test result. If the second test result is a pass, a high current test is performed to generate a third test result. If the third test result is a pass, each bypass protection thyristor is determined to have passed the test. This ensures that all thyristors put into engineering applications have passed rigorous multi-stage testing, reducing the risk of power module failure during converter valve operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0061] Figure 1 A flowchart of the steps of a method for detecting bypass protection thyristors of a flexible DC converter valve power module provided by an embodiment of the present invention;

[0062] Figure 2 A schematic diagram of a bypass protection thyristor current flow function after breakdown provided by an embodiment of the present invention;

[0063] Figure 3 A schematic diagram of a flexible DC converter valve composed of a power module provided in an embodiment of the present invention;

[0064] Figure 4 A schematic diagram of the structure of a test circuit provided by an embodiment of the present invention;

[0065] Figure 5 A schematic diagram of a leakage current curve provided by an embodiment of the present invention;

[0066] Figure 6 A schematic diagram of a voltage-equalizing circuit for an equivalent series power module provided by an embodiment of the present invention;

[0067] Figure 7 This is a structural block diagram of a detection device for bypass protection thyristors of a flexible DC converter valve power module provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0068] An embodiment of the present invention provides a method and related equipment for detecting bypass protection thyristors of a flexible DC converter valve power module, which is used to solve the technical problem that due to inconsistent quality control of bypass protection thyristors, the breakover voltage deviation of the bypass protection thyristors is large, thereby increasing the risk of failure of the flexible DC transmission system.

[0069] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0070] See also Figure 1 , Figure 1 A flowchart of the steps of a method for detecting bypass protection thyristors of a flexible DC converter valve power module provided by an embodiment of the present invention.

[0071] The present invention provides a method for detecting a bypass protection thyristor of a flexible DC converter valve power module, comprising:

[0072] Step 101: Selecting a thyristor to be tested from a plurality of bypass protection thyristors and connecting it to a flexible DC converter valve power module, and increasing the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve;

[0073] The bypass protection thyristor in this embodiment refers to a thyristor with a breakover function and capable of withstanding both forward and reverse arm currents, and its breakdown voltage is between 4200V and 4400V. Taking a half-bridge module as an example, the bypass protection thyristor's breakover function after the breakover is shown in the figure below. Figure 2 As shown, the flexible DC converter valve power module is as follows Figure 3As shown in the figure, a flexible DC converter valve using a modular multilevel converter is composed of multiple power modules connected in series on each bridge arm. The power modules can be all half-bridge power modules, all full-bridge power modules, or a combination of half-bridge power modules and full-bridge power modules. A half-bridge power module mainly consists of two switching devices - a diode pair (or a pair with the same function) and a DC capacitor. Figure 3 The full-bridge power module mainly consists of four switching devices - diode pairs (or with the same function) and DC capacitors.

[0074] In this embodiment, after obtaining multiple bypass protection thyristors of the same batch, any one bypass protection thyristor is selected as the thyristor to be tested, and it is connected to the flexible DC converter valve power module to obtain the following Figure 4 The test circuit shown. At this time, according to the first preset gradient, the power module is used as the test object, and the AC voltage of the test is continuously increased to below the transition breakdown voltage of 4200V, and the AC current of the test circuit is increased. This AC current is the current flowing into the power module, part of which flows into the thyristor and part flows into the capacitor and equalizing resistor of the power module. The current flowing into the thyristor at this time is called leakage current. When the leakage current reaches 500mA, the test ends. When the capacitor voltage stabilizes and no longer increases, it is determined that the leakage current stage has ended, and the voltage, current and leakage current data at this time are recorded. Based on the above data, the leakage current stage volt-ampere characteristic curve is drawn to verify the blocking ability of the thyristor under test at low current.

[0075] Step 102, performing leakage current detection according to the volt-ampere characteristic curve to generate a first detection result;

[0076] In one example of the present application, step 102 may include the following sub-steps:

[0077] Compare the volt-ampere characteristic curve with the preset leakage current curve and calculate the curve similarity;

[0078] If the curve similarity is greater than or equal to the preset similarity threshold, the first test result is determined to be passed;

[0079] If the curve similarity is less than a preset similarity threshold, the first detection result is determined to be failed.

[0080] The leakage current curve is as follows Figure 5 As shown, at this stage, the internal energy of the power module reaches dynamic equilibrium, and the thyristor stably flows leakage current. In this embodiment, after the volt-ampere characteristic curve is plotted, the volt-ampere characteristic curve is compared with a preset leakage current curve, and the corresponding curve similarity is calculated. If the curve similarity is greater than or equal to a preset similarity threshold, the first test result is determined to be a pass; if the curve similarity is less than the preset similarity threshold, the first test result is determined to be a fail.

[0081] In addition, during the leakage current detection phase, when the converter valve is fully charged and in the locked state, the main factors affecting the power module voltage balancing are the voltage balancing resistor, the energy source, and the leakage current characteristics of the thyristor. A simplified equivalent series power module voltage balancing circuit is used as an example for theoretical analysis. Figure 6 The power modules are mainly equalized by equalizing resistors. For the static equalization effect of each power module of the converter valve, it is necessary to analyze the static working current of the internal components of the power module, mainly including: the static leakage current of the DC capacitor , discharge resistor current , the input current of the energy source and thyristor leakage current Therefore, the total static operating current of the power module is for:

[0082]

[0083] Where U is the voltage on the power module capacitor; Ric is the DC capacitor insulation resistance, which should be in the megohm range or above; R is the balancing resistor, which can be 34kΩ; A and B are parameters of the volt-ampere characteristic curve. Since Ric >> R, the static leakage current of the capacitor can be ignored. PS is the input power of the energy source, which can be 20W (including the power consumption of all circuit boards powered by the energy source and the power source's own losses). The energy source is a constant-power load, and its leakage current is inversely proportional to the voltage, while the balancing resistor and thyristor leakage current are directly proportional to the voltage.

[0084] When the leakage current characteristics of the thyristor are not considered in the circuit, it is assumed that due to the resistance of the voltage-sharing resistor and the power dispersion of the energy source, the voltage U1 of the first power module is greater than the voltage U2 of the second power module. Definition:

[0085]

[0086] In this state, considering the power module contains thyristors, since U1 > U2, the current flowing through the thyristors, IT1 > IT2. At this point, if the voltage remains constant, the increased current flowing through the thyristors cannot guarantee a constant current across the entire series-connected power module system. Therefore, to rebalance the first power module's resistive current, a larger proportion of the leakage current will be diverted by the thyristors. This means that the voltage of the first power module will decrease while the voltage of the second power module will increase. Therefore, the thyristor's leakage current characteristic is beneficial to the circuit voltage balancing characteristics, reducing the dispersion of voltages between power modules and providing a greater safety margin for the power module voltages.

[0087] Step 103: If the first test result is passed, a low current test is performed to generate a second test result;

[0088] In an example of the present application, step 103 may include the following sub-steps:

[0089] If the first detection result is passed, the AC voltage and AC current are increased according to a second preset gradient, and the voltage across the thyristor to be tested is detected;

[0090] When the voltage at both ends returns to zero, the current AC voltage and AC current are maintained and the capacitor voltage of the flexible DC converter valve power module is monitored in real time;

[0091] If the current holding time of the flexible DC converter valve power module is not less than the preset holding threshold and the capacitor voltage drops to zero, the current of the thyristor to be tested is disconnected;

[0092] If the resistance of the thyristor to be tested is in a high resistance state, the second test result is determined to be passed;

[0093] If the current holding time of the flexible DC converter valve power module is less than the preset holding threshold, or the capacitor voltage does not drop to zero, or the resistance of the thyristor to be tested is not in a high-resistance state, the second test result is determined to be failed.

[0094] In this embodiment, if the first test result is a pass, the test system test voltage and current can be further increased based on the leakage current. The bypass thyristor will enter the low current stage. When the voltage across the monitoring thyristor changes from the capacitor voltage to zero, the test voltage and current are maintained unchanged. The power module is maintained for a period of no less than a preset holding threshold of 2 hours. During this period, the capacitor voltage gradually drops to zero. The power can be turned off. If the measured thyristor resistance is still in a high-resistance state, it indicates that the thyristor has undergone a transition in this low current stage but has not been broken down. After the transition, it stably passes a low current, and the second test result is determined to be a pass.

[0095] If the current holding time of the flexible DC converter valve power module is less than the preset holding threshold, or the capacitor voltage does not drop to zero, or the resistance of the thyristor to be tested is not in a high-resistance state, the second test result is determined to be failed.

[0096] Step 104: If the second test result is passed, perform a high current test to generate a third test result;

[0097] In one example of the present application, step 104 may include the following sub-steps:

[0098] If the second detection result is passed, the AC voltage and AC current are increased according to a third preset gradient, and the module voltage of the flexible DC converter valve power module is monitored;

[0099] When the thyristor to be tested is broken down and the module voltage decays to zero, the current of the thyristor to be tested is disconnected;

[0100] If the resistance of the thyristor to be tested is within the preset resistance range, the third test result is determined to be passed;

[0101] If the thyristor to be tested is not broken down, or the module voltage is not decayed and is not zero, or the resistance of the thyristor to be tested is not within the preset resistance range, the third test result is determined to be failed.

[0102] In this embodiment, after completing the low-current test, a high-current test can be performed. The voltage and current are further increased until the thyristor breaks down, at which point the entire current flows through the thyristor. After power is removed, the thyristor resistance is measured (approximately tens of milliohms, indicating breakdown conduction). When the bypass thyristor breaks down, the power module voltage is 4320V. Afterward, the power module voltage decays to 0. After breakdown, the entire test current flows through the thyristor. After power is removed, the thyristor resistance is measured to be approximately tens of milliohms, indicating that the thyristor has broken down after the transition, thus achieving long-term stable current flow in the power module.

[0103] Step 105: If the third test result is passed, it is determined that each bypass protection thyristor has passed the test.

[0104] In this embodiment, if the third test result is also a pass, the remaining bypass protection thyristors can be determined to have passed the test, completing the random inspection of the bypass protection thyristors, and can be applied to various power modules. The thyristor volt-ampere characteristics are verified through a three-stage test, and the optimization effect of leakage current on voltage balancing is combined with simulation analysis to ensure the reliability of the module under normal operation and fault scenarios. The thyristor breakdown voltage threshold is confirmed to ensure reliable bypass in the event of a fault, and the leakage current characteristics are used to reduce voltage dispersion and reduce the risk of module overvoltage. At the same time, it provides a data basis for the thyristor selection and voltage balancing resistor configuration of the converter valve power module, optimizing the topology design of the modular multilevel converter (MMC).

[0105] In another example of the present application, the method further includes the following steps:

[0106] If the first test result, the second test result or the third test result is failed, it is determined that the thyristor to be tested has failed the test;

[0107] Selecting a new thyristor to be tested from the remaining multiple bypass protection thyristors, and connecting the new thyristor to be tested to the flexible DC converter valve power module;

[0108] Jump to the step of increasing the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve;

[0109] If the number of times that the thyristor to be tested is determined to have failed the test is greater than a preset determination threshold, it is determined that each bypass protection thyristor has failed the test.

[0110] In an embodiment of the present application, if a single thyristor to be tested fails the test, a retry mechanism is activated, and a new sample is selected from the remaining thyristors in the same batch for retesting. At the same time, a maximum number of retries for a single sample is set (a preset judgment threshold). If the cumulative number of unqualified times exceeds the threshold, the entire batch of thyristors is determined to have failed the test.

[0111] In addition, when the bypass protection thyristor fails the test, a corresponding batch test report can be generated and the reasons for failure can be marked, such as breakdown voltage offset, leakage current exceeding the standard, etc.

[0112] In an embodiment of the present application, a thyristor to be tested is selected from a plurality of bypass protection thyristors and connected to a flexible DC converter valve power module, and the AC voltage and AC current are increased according to a first preset gradient to construct a volt-ampere characteristic curve; leakage current detection is performed according to the volt-ampere characteristic curve to generate a first detection result; if the first detection result is a pass, a small current detection is performed to generate a second detection result; if the second detection result is a pass, a large current detection is performed to generate a third detection result; if the third detection result is a pass, it is determined that each bypass protection thyristor has passed the test, thereby ensuring that the thyristors put into engineering application have passed strict multi-stage testing, thereby reducing the risk of power module failure during the operation of the converter valve.

[0113] See also Figure 7 , Figure 7 This is a structural block diagram of a detection device for bypass protection thyristors of a flexible DC converter valve power module provided by an embodiment of the present invention.

[0114] An embodiment of the present invention further provides a detection device for a bypass protection thyristor of a flexible DC converter valve power module, comprising:

[0115] A curve construction module 1001 is configured to select a thyristor to be tested from a plurality of bypass protection thyristors, connect the thyristor to the flexible DC converter valve power module, and increase the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve;

[0116] A leakage current detection module 1002 is configured to perform leakage current detection according to a volt-ampere characteristic curve and generate a first detection result;

[0117] A low current detection module 1003 is configured to perform a low current detection and generate a second detection result if the first detection result is a pass;

[0118] A high current detection module 1004 is configured to perform a high current detection and generate a third detection result if the second detection result is a pass;

[0119] The detection pass determination module 1005 is configured to determine whether each bypass protection thyristor has passed the detection if the third detection result is pass.

[0120] Optionally, the leakage current detection module 1002 is specifically configured to:

[0121] Compare the volt-ampere characteristic curve with the preset leakage current curve and calculate the curve similarity;

[0122] If the curve similarity is greater than or equal to the preset similarity threshold, the first test result is determined to be passed;

[0123] If the curve similarity is less than a preset similarity threshold, the first detection result is determined to be failed.

[0124] Optionally, the low current detection module 1003 is specifically configured to:

[0125] If the first detection result is passed, the AC voltage and AC current are increased according to a second preset gradient, and the voltage across the thyristor to be tested is detected;

[0126] When the voltage at both ends returns to zero, the current AC voltage and AC current are maintained and the capacitor voltage of the flexible DC converter valve power module is monitored in real time;

[0127] If the current holding time of the flexible DC converter valve power module is not less than the preset holding threshold and the capacitor voltage drops to zero, the current of the thyristor to be tested is disconnected;

[0128] If the resistance of the thyristor to be tested is in a high resistance state, the second test result is determined to be passed;

[0129] If the current holding time of the flexible DC converter valve power module is less than the preset holding threshold, or the capacitor voltage does not drop to zero, or the resistance of the thyristor to be tested is not in a high-resistance state, the second test result is determined to be failed.

[0130] Optionally, the high current detection module 1004 is specifically configured to:

[0131] If the second detection result is passed, the AC voltage and AC current are increased according to a third preset gradient, and the module voltage of the flexible DC converter valve power module is monitored;

[0132] When the thyristor to be tested is broken down and the module voltage decays to zero, the current of the thyristor to be tested is disconnected;

[0133] If the resistance of the thyristor to be tested is within the preset resistance range, the third test result is determined to be passed;

[0134] If the thyristor to be tested is not broken down, or the module voltage is not decayed and is not zero, or the resistance of the thyristor to be tested is not within the preset resistance range, the third test result is determined to be failed.

[0135] Optionally, the device further includes a recheck module, specifically configured to:

[0136] If the first test result, the second test result or the third test result is failed, it is determined that the thyristor to be tested has failed the test;

[0137] Selecting a new thyristor to be tested from the remaining multiple bypass protection thyristors, and connecting the new thyristor to be tested to the flexible DC converter valve power module;

[0138] Jump to the step of increasing the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve;

[0139] If the number of times that the thyristor to be tested is determined to have failed the test is greater than a preset determination threshold, it is determined that each bypass protection thyristor has failed the test.

[0140] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0141] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules is merely a logical function division. In actual implementation, there may be other division methods, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0142] The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules may be selected to achieve the purpose of the present embodiment according to actual needs.

[0143] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting bypass protection thyristors of a flexible DC converter valve power module, characterized in that: include: Selecting a thyristor to be tested from a plurality of bypass protection thyristors and connecting it to a flexible DC converter valve power module, and increasing the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve; Perform leakage current detection according to the volt-ampere characteristic curve to generate a first detection result; If the first detection result is passed, a low current detection is performed to generate a second detection result; If the second detection result is passed, performing a high current detection to generate a third detection result; If the third detection result is passed, it is determined that each of the bypass protection thyristors has passed the test.

2. The method according to claim 1, characterized in that The performing leakage current detection according to the volt-ampere characteristic curve to generate a first detection result includes: Comparing the volt-ampere characteristic curve with a preset leakage current curve to calculate the curve similarity; If the curve similarity is greater than or equal to a preset similarity threshold, the first detection result is determined to be passed; If the curve similarity is less than a preset similarity threshold, the first detection result is determined to be failed.

3. The method according to claim 1, characterized in that If the first detection result is passed, performing a low current detection to generate a second detection result includes: If the first detection result is passed, increasing the AC voltage and the AC current according to a second preset gradient, and detecting the voltage across the thyristor to be tested; When the voltages at both ends return to zero, the AC voltage and AC current at the current moment are maintained and the capacitor voltage of the flexible DC converter valve power module is monitored in real time; If the current holding time of the flexible DC converter valve power module is not less than the preset holding threshold and the capacitor voltage drops to zero, the current of the thyristor to be tested is disconnected; If the resistance of the thyristor to be tested is in a high-resistance state, determining that the second test result is passed; If the current holding time of the flexible DC converter valve power module is less than the preset holding threshold, or the capacitor voltage does not drop to zero, or the resistance of the thyristor to be tested is not in a high-resistance state, the second detection result is determined to be failed.

4. The method according to claim 1, wherein If the second detection result is passed, performing a high current detection to generate a third detection result includes: If the second detection result is passed, increasing the AC voltage and the AC current according to a third preset gradient, and monitoring the module voltage of the flexible DC converter valve power module; When the thyristor to be tested is broken down and the module voltage decays to zero, the current of the thyristor to be tested is disconnected; If the resistance of the thyristor to be tested is within a preset resistance range, determining that the third test result is passed; If the thyristor to be tested is not broken down, or the module voltage is not decayed to zero, or the resistance of the thyristor to be tested is not within a preset resistance range, the third test result is determined to be failed.

5. The method according to claim 1, wherein The method further comprises: If the first test result, the second test result or the third test result is failed, it is determined that the thyristor to be tested has failed the test; Selecting a new thyristor to be tested from the remaining plurality of bypass protection thyristors, and connecting the new thyristor to be tested to the flexible DC converter valve power module; Jump to the step of increasing the AC voltage and AC current according to the first preset gradient to construct a volt-ampere characteristic curve; If the number of times that the thyristor to be tested is determined to have failed the test is greater than a preset determination threshold, it is determined that each of the bypass protection thyristors has failed the test.

6. A detection device for bypass protection thyristors of a flexible DC converter valve power module, characterized in that: include: a curve construction module, configured to select a thyristor to be tested from a plurality of bypass protection thyristors, connect the thyristor to the flexible DC converter valve power module, and increase the AC voltage and AC current according to a first preset gradient to construct a volt-ampere characteristic curve; a leakage current detection module, configured to perform leakage current detection according to the volt-ampere characteristic curve and generate a first detection result; A low current detection module, configured to perform a low current detection and generate a second detection result if the first detection result is a pass; A high current detection module, configured to perform high current detection and generate a third detection result if the second detection result is a pass; The detection pass determination module is configured to determine whether each of the bypass protection thyristors has passed the detection if the third detection result is a pass.

7. The device according to claim 6, characterized in that The leakage current detection module is specifically used for: Comparing the volt-ampere characteristic curve with a preset leakage current curve to calculate the curve similarity; If the curve similarity is greater than or equal to a preset similarity threshold, the first detection result is determined to be passed; If the curve similarity is less than a preset similarity threshold, the first detection result is determined to be failed.

8. The device according to claim 6, characterized in that The small current detection module is specifically used for: If the first detection result is passed, increasing the AC voltage and the AC current according to a second preset gradient, and detecting the voltage across the thyristor to be tested; When the voltages at both ends return to zero, the AC voltage and AC current at the current moment are maintained and the capacitor voltage of the flexible DC converter valve power module is monitored in real time; If the current holding time of the flexible DC converter valve power module is not less than the preset holding threshold and the capacitor voltage drops to zero, the current of the thyristor to be tested is disconnected; If the resistance of the thyristor to be tested is in a high-resistance state, determining that the second test result is passed; If the current holding time of the flexible DC converter valve power module is less than the preset holding threshold, or the capacitor voltage does not drop to zero, or the resistance of the thyristor to be tested is not in a high-resistance state, the second detection result is determined to be failed.

9. The device according to claim 6, characterized in that The high current detection module is specifically used for: If the second detection result is passed, increasing the AC voltage and the AC current according to a third preset gradient, and monitoring the module voltage of the flexible DC converter valve power module; When the thyristor to be tested is broken down and the module voltage decays to zero, the current of the thyristor to be tested is disconnected; If the resistance of the thyristor to be tested is within a preset resistance range, determining that the third test result is passed; If the thyristor to be tested is not broken down, or the module voltage is not decayed to zero, or the resistance of the thyristor to be tested is not within a preset resistance range, the third test result is determined to be failed.

10. The device according to claim 6, characterized in that The device also includes a retest module, specifically configured to: If the first test result, the second test result or the third test result is failed, it is determined that the thyristor to be tested has failed the test; Selecting a new thyristor to be tested from the remaining plurality of bypass protection thyristors, and connecting the new thyristor to be tested to the flexible DC converter valve power module; Jump to the step of increasing the AC voltage and AC current according to the first preset gradient to construct a volt-ampere characteristic curve; If the number of times that the thyristor to be tested is determined to have failed the test is greater than a preset determination threshold, it is determined that each of the bypass protection thyristors has failed the test.

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