Detection method and system adaptable to multiple types of high-voltage direct current commutation failures

Abstract

A detection method and system adaptable to multiple types of high-voltage direct current commutation failures, relating to the technical field of electric power. In the present invention, on the basis of a single commutation failure criterion obtained via pre-analysis, a valve-side current waveform of a target system is first analyzed to accurately obtain a single commutation result; then an interval between two commutation failures is determined on the basis of a commutation failure moment of the single commutation failure; and by incorporating a dual-commutation failure criterion obtained via pre-analysis, a dual-commutation result is finally obtained. In the present invention, results of different types of commutations in a high-voltage direct current transmission system can be accurately identified, whether different commutation failures occur can be accurately determined, thereby improving the operation stability of the high-voltage direct current transmission system.

Description

A method and system for detecting commutation failures in high-voltage DC transmissions that are compatible with multiple types.

[0001] This application claims priority to Chinese Patent Application No. 202510023399.3, filed on January 7, 2025, entitled "A Method and System for Detecting Multiple Types of High Voltage Direct Current Commutation Failure", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of power technology, and in particular to a method and system for detecting commutation failures of various types of high-voltage direct current. Background Technology

[0003] The susceptibility of inverters to commutation failure is one of the main drawbacks of HVDC transmission projects using grid-commutated converters. In a single power frequency cycle, a 6-pulse converter will experience at most two commutation failures, and there are only three types of commutation failures: single commutation failure, two consecutive commutation failures, and two discontinuous commutation failures. Currently, in practical engineering, a differential current criterion based on the AC / DC current on the valve side is used to detect commutation failures. This differential current criterion characterizes the abnormal valve state after the converter bypasses, and it lacks the ability to detect commutation failures before bypass, leading to a mismatch between the differential current timing of the valve zone protection criterion and the timing of the abnormal valve state. Furthermore, the differential current criterion is susceptible to insufficient sensitivity due to various factors such as fault type, system strength, fault intensity, DC operating conditions, fault closing angle, and control regulation.

[0004] Therefore, accurate detection of commutation failure is crucial for the stable operation of high-voltage direct current (HVDC) transmission systems. Currently, existing technologies for commutation failure detection utilize two typical dynamic characteristics to identify a single commutation failure. However, in actual operating scenarios, power systems exhibit complex and variable operating states, with diverse fault types and conditions. Relying solely on two typical dynamic characteristics cannot comprehensively cover all possible situations. This leads to the inability to accurately identify commutation failures under certain special operating conditions or complex fault combinations, thus affecting the reliability and stability of the entire HVDC transmission system. Summary of the Invention

[0005] This invention provides a method and system for detecting commutation failures in high-voltage direct current (HVDC) systems that are compatible with various types, thus solving the technical problem of how to improve the operational stability of HVDC transmission systems.

[0006] The first aspect of this invention provides a method for detecting multiple types of high-voltage direct current commutation failures, comprising:

[0007] In response to a commutation detection request for the target system, the valve-side current waveform and commutation characteristic data of the target system are acquired;

[0008] Based on the valve-side current waveform and the preset first commutation failure criterion, the first commutation result is determined;

[0009] When the result of a single commutation is a commutation failure, the interval between two commutation failures is determined based on the commutation failure time and the commutation characteristic data.

[0010] Based on the two commutation failure intervals, the valve-side current waveform, and the preset two commutation failure criteria, the two commutation results are determined.

[0011] Optionally, the preset first-phase commutation failure criterion includes an atypical commutation failure criterion and a typical commutation failure criterion, and the step of determining the first-phase commutation result based on the valve-side current waveform and the preset first-phase commutation failure criterion includes:

[0012] If the valve-side current waveform satisfies the atypical commutation failure criterion, then the target system is determined to have experienced an atypical commutation failure.

[0013] If the valve-side current waveform satisfies the typical commutation failure criterion, then the target system is determined to have experienced a typical commutation failure.

[0014] If there is no atypical commutation failure or no typical commutation failure, then a commutation result is determined as no commutation failure has occurred.

[0015] When either the atypical commutation failure or the typical commutation failure exists, a commutation result is determined to be a commutation failure.

[0016] Optionally, determining that the target system has experienced an atypical commutation failure when the valve-side current waveform satisfies the atypical commutation failure criterion includes:

[0017] Obtain the first phase valve-side current waveform and the second phase valve-side current waveform when the valve-side current is negative.

[0018] Determine whether the current waveform on the valve side of the first phase has an increasing trend;

[0019] If the current waveform on the first phase valve side shows an increasing trend, then determine whether the increasing trend is greater than a preset first current threshold.

[0020] If the increasing trend is greater than the preset first current threshold, it is determined that there is a first commutation failure feature;

[0021] Determine whether the current waveform on the second phase valve side has a minimum value;

[0022] If the current waveform on the valve side of the second phase has a minimum value, it is determined that there is a second commutation failure characteristic.

[0023] After the second phase valve side current waveform reaches the minimum value, determine whether the increasing trend of the second phase valve side current waveform is greater than the preset second current threshold.

[0024] If the increasing trend of the current waveform on the valve side of the second phase is greater than the preset second current threshold, it is determined that there is a third commutation failure feature.

[0025] If the valve-side current waveform simultaneously exhibits the first commutation failure characteristic, the second commutation failure characteristic, and the third commutation failure characteristic, then the target system is determined to have experienced an atypical commutation failure.

[0026] Optionally, the commutation characteristic data includes steady-state commutation angle, steady-state trigger angle, steady-state trigger phase interval, first converter valve pre-contact angle, and second converter valve pre-contact angle. The two commutation failure intervals include two consecutive commutation failure intervals and two discontinuous commutation failure intervals. Determining the two commutation failure intervals based on the commutation failure time of one commutation failure and the commutation characteristic data includes:

[0027] Using the commutation failure time and the steady-state commutation angle, the lower limit of the interval between the two consecutive commutation failures is determined;

[0028] Using the commutation failure time and the steady-state firing angle, the upper limit of the interval between the two consecutive commutation failures is determined;

[0029] The lower limit of the interval between the two discontinuous commutation failures is determined by using the commutation failure time, the steady-state trigger angle, and the pre-contact angle of the first converter valve.

[0030] The upper limit of the interval between the two discontinuous commutation failures is determined by using the commutation failure time, the steady-state trigger phase interval, the steady-state trigger angle, and the pre-contact angle of the second converter valve.

[0031] Optionally, the preset two-stage commutation failure criteria include two consecutive commutation failure criteria and two discontinuous commutation failure criteria. The step of determining the two commutation results based on the two commutation failure intervals, the valve-side current waveform, and the preset two-stage commutation failure criteria includes:

[0032] Based on the two consecutive commutation failure intervals, the valve-side current waveform, and the two consecutive commutation failure criteria, the results of the two consecutive commutations are determined.

[0033] Based on the two consecutive commutation failure intervals, the two discontinuous commutation failure intervals, the valve-side current waveform, and the two discontinuous commutation failure criteria, the results of the two discontinuous commutation failures are determined.

[0034] Optionally, determining the two consecutive commutation results based on the two consecutive commutation failure intervals, the valve-side current waveform, and the two consecutive commutation failure criteria includes:

[0035] When a commutation failure is detected, it is determined whether the running time of the target system is within the interval between two consecutive commutation failures;

[0036] If the running time of the target system is within the interval of the two consecutive commutation failures, then it is determined that there is a fourth commutation failure feature.

[0037] Determine whether the current waveform on the valve side of the first phase has an increasing trend;

[0038] If the current waveform on the first phase valve side shows an increasing trend, then determine whether the current waveform on the first phase valve side has a maximum value.

[0039] If the current waveform on the first phase valve side has a maximum value, then determine whether the increasing trend of the current waveform on the first phase valve side has a decay trend after reaching the maximum value.

[0040] When the increasing trend of the current waveform on the valve side of the first phase reaches its maximum value and then shows a decaying trend, it is determined that there is a fifth commutation failure characteristic.

[0041] Determine whether the attenuation trend is greater than a preset third current threshold;

[0042] If the attenuation trend is greater than the preset third current threshold, it is determined that there is a sixth commutation failure feature;

[0043] The first phase valve-side current, obtained from the waveform of the first phase valve-side current, is the first transformed phase valve-side current in the transformed coordinate system.

[0044] The first sum is generated by summing the current on the first phase valve side and the current on the first changing phase valve side.

[0045] Determine whether the first sum is less than a preset first sum threshold;

[0046] If the first sum is less than the preset first sum threshold, then a seventh commutation failure feature is determined to exist.

[0047] If the valve-side current waveform does not simultaneously exhibit the fourth commutation failure feature, the fifth commutation failure feature, the sixth commutation failure feature, and the seventh commutation failure feature, then it is determined that the target system has not experienced two consecutive commutation failures, and it is determined that an eighth commutation failure feature exists.

[0048] If the valve-side current waveform simultaneously exhibits the fourth commutation failure characteristic, the fifth commutation failure characteristic, the sixth commutation failure characteristic, and the seventh commutation failure characteristic, then it is determined that the target system has experienced two consecutive commutation failures.

[0049] Optionally, determining the two discontinuous commutation results based on the two consecutive commutation failure intervals, the two discontinuous commutation failure intervals, the valve-side current waveform, and the two discontinuous commutation failure criteria includes:

[0050] When a commutation failure is detected, it is determined whether the running time of the target system is within the interval between the two discontinuous commutation failures.

[0051] If the running time of the target system is within the interval between the two discontinuous commutation failures, then it is determined that there is a ninth commutation failure feature.

[0052] Determine whether the current waveform on the first phase valve side exhibits a decay trend;

[0053] If the current waveform on the first phase valve side has a decaying trend, then determine whether there is an increasing trend after the decaying trend of the current waveform on the first phase valve side reaches a minimum value.

[0054] If the attenuation trend of the current waveform on the valve side of the first phase reaches a minimum value and then shows an increasing trend, it is determined that there is a tenth commutation failure feature.

[0055] Determine whether the increasing trend is greater than a preset fourth current threshold;

[0056] If the increasing trend is greater than the preset fourth current threshold, it is determined that there is an eleventh commutation failure feature.

[0057] A second sum is generated by summing the first phase valve-side current from the first phase valve-side current waveform and the second phase valve-side current from the second phase valve-side current waveform.

[0058] Determine whether the second sum is less than a preset second sum threshold;

[0059] If the second sum is less than the preset second sum threshold, then the twelfth commutation failure feature is determined to exist;

[0060] If the valve-side current waveform does not simultaneously exhibit the ninth commutation failure feature, the tenth commutation failure feature, the eleventh commutation failure feature, and the twelfth commutation failure feature, or if the eighth commutation failure feature is present, then it is determined that the target system has not experienced two discontinuous commutation failures.

[0061] If the valve-side current waveform simultaneously exhibits the ninth commutation failure feature, the tenth commutation failure feature, the eleventh commutation failure feature, and the twelfth commutation failure feature, and does not exhibit the eighth commutation failure feature, then the target system is determined to have experienced two discontinuous commutation failures.

[0062] The second aspect of this invention provides a multi-type high-voltage DC commutation failure detection system, comprising:

[0063] The response module is used to respond to the commutation detection request of the target system and acquire the valve-side current waveform and commutation characteristic data of the target system.

[0064] A single commutation determination module is used to determine the single commutation result based on the valve-side current waveform and a preset single commutation failure criterion.

[0065] The interval determination module is used to determine the interval between two commutation failures based on the commutation failure time and the commutation characteristic data when the result of a commutation failure is a commutation failure.

[0066] The two-phase commutation determination module is used to determine the two-phase commutation results based on the two-phase commutation failure intervals, the valve-side current waveform, and the preset two-phase commutation failure criteria.

[0067] A third aspect of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the multi-type high-voltage DC commutation failure detection method as described in any of the preceding claims.

[0068] The fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements the method for detecting multiple types of high-voltage DC commutation failure as described in any of the preceding claims.

[0069] As can be seen from the above technical solutions, the present invention has the following advantages:

[0070] In this invention, in response to a commutation detection request for the target system, the valve-side current waveform and commutation characteristic data of the target system are acquired. Based on the valve-side current waveform and a preset first commutation failure criterion, a first commutation result is determined. When the first commutation result indicates a first commutation failure, the interval between two commutation failures is determined based on the commutation failure time and commutation characteristic data. Based on the interval between two commutation failures, the valve-side current waveform, and the preset two commutation failure criterion, the results of two commutations are determined. This invention first analyzes the valve-side current waveform of the target system using a pre-analyzed first commutation failure criterion to accurately obtain the first commutation result. Then, it determines the interval between two commutation failures based on the commutation failure time of the first commutation failure. Combining this with the pre-analyzed two commutation failure criterion, the results of two commutations are finally obtained. This invention can accurately identify the results of different types of commutation in a high-voltage direct current transmission system, accurately determine whether different commutation failure situations have occurred, and improve the operational stability of the high-voltage direct current transmission system. Attached Figure Description

[0071] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0072] Figure 1 is a flowchart of the steps of a method for detecting commutation failure of high voltage DC transmission that is adapted to multiple types, provided in Embodiment 1 of the present invention.

[0073] Figure 2 is a flowchart of a multi-type high-voltage DC commutation failure detection method provided in Embodiment 2 of the present invention;

[0074] Figure 3 is a schematic diagram of the valve-side current waveform, which is a typical feature of the first commutation failure.

[0075] Figure 4 is a schematic diagram of the valve-side current waveform of the second typical characteristic of a single commutation failure.

[0076] Figure 5 is a schematic diagram of the valve-side current waveform, which shows the atypical characteristics of a single commutation failure.

[0077] Figure 6 is a schematic diagram of the valve-side current waveform after two consecutive commutation failures;

[0078] Figure 7 is a schematic diagram of the valve-side current waveforms after two discontinuous commutation failures.

[0079] Figure 8 shows the valve-side current waveform of the first phase, i. x A schematic diagram of the criterion logic;

[0080] Figure 9 shows the valve-side current waveform of the second phase, i.y A schematic diagram of the criterion logic;

[0081] Figure 10 is a schematic diagram of obtaining the effect level in different time intervals of two commutation failures;

[0082] Figure 11 shows the valve-side current waveform of the first phase, i. x A schematic diagram of the attenuation criterion;

[0083] Figure 12 is a schematic diagram of the acquisition of detection signals for two consecutive commutation failures;

[0084] Figure 13 is a schematic diagram of the acquisition of detection signals for two discontinuous commutation failures;

[0085] Figure 14 is a schematic diagram of the commutation failure detection loop in DC engineering model 1 under a three-phase fault.

[0086] Figure 15 is a schematic diagram of the commutation failure detection loop when phase A fault occurs in DC engineering model 1.

[0087] Figure 16 is a schematic diagram of the commutation failure detection loop when a C-phase fault occurs in DC engineering model 2.

[0088] Figure 17 is a schematic diagram of the commutation failure detection loop in DC engineering model 2 under three-phase fault.

[0089] Figure 18 is a schematic diagram of the commutation failure detection loop when phase A fault occurs in DC engineering model 2.

[0090] Figure 19 is a structural block diagram of a multi-type high-voltage DC commutation failure detection system provided in Embodiment 3 of the present invention;

[0091] Figure 20 is a structural block diagram of a computer device provided in Embodiment 4 of the present invention. Detailed Implementation

[0092] This invention provides a method and system for detecting commutation failures in high-voltage direct current (HVDC) systems that are compatible with various types, in order to address the technical problem of improving the operational stability of HVDC transmission systems.

[0093] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0094] Existing technologies disclose a method for predicting commutation failure by calculating the turn-off angle using the node impedance matrix and node voltage interaction factor, and comparing the turn-off angle with the minimum turn-off angle. However, this method has limited effectiveness. Existing technologies also disclose a method for detecting commutation failure using the dynamic characteristics of valve current and valve voltage, respectively. However, in practice, most HVDC projects cannot obtain valve current and valve voltage information. Existing technologies also disclose a method for identifying primary commutation failure using two typical dynamic characteristics of the converter transformer valve-side current under AC faults. Compared to practical engineering solutions, this method improves the reliability and speed of primary commutation failure detection. However, for atypical primary commutation failures, this method may fail to operate or may malfunction. Existing technologies also disclose a method for predicting commutation failure by introducing a waveform similarity coefficient, but the activation threshold for the commutation failure prediction stage lacks theoretical basis. Existing technologies also disclose a method for calculating valve current using the polarity characteristics of valve-side current and judging commutation failure based on converter valve conduction and turn-off criteria, but this scheme is difficult to implement in engineering.

[0095] Therefore, while the aforementioned technologies provide a reference for detecting the operating status of converters, they still suffer from problems such as poor timeliness, low reliability, and lack of identification of commutation failure types. Actual engineering solutions and existing technologies still have significant room for improvement in terms of detection reliability, sensitivity, and engineering implementation, and none of them can identify commutation failure types.

[0096] In high-voltage direct current (HVDC) transmission systems, accurate detection of commutation failure is crucial for stable system operation. However, existing technologies for commutation failure detection have several shortcomings, resulting in insufficient detection accuracy. For example, some existing technologies utilize the typical dynamic characteristics of the valve-side current of the converter transformer under AC faults to identify primary commutation failure. While this improves the reliability and speed of primary commutation failure detection to some extent, existing detection methods often fail to operate or operate falsely for atypical characteristics of the valve-side current. This means that in actual HVDC system operation, the inability to accurately detect commutation failures under such special circumstances may threaten system stability.

[0097] Furthermore, existing technologies lack in-depth research on two consecutive and two discontinuous commutation failures when dealing with multiple commutation failures. Specifically, there is no clear method for determining the time interval range of two consecutive and two discontinuous commutation failures, nor is there analysis of the operational level structure for this situation. At the same time, the lack of effective detection criteria and structures specifically for two-phase commutation failures makes it difficult for existing technologies to accurately detect and judge these complex commutation failure scenarios, thus affecting the safe, stable, and efficient operation of HVDC systems.

[0098] In summary, existing technologies have insufficient accuracy in commutation failure detection, mainly in terms of limited ability to detect commutation failures with atypical characteristics and imperfect detection methods for multiple commutation failures. This poses potential risks and challenges to the stable operation of HVDC systems.

[0099] This invention provides a detection scheme for multiple types of high-voltage DC commutation failure based on the valve-side current characteristics in different time intervals. It accurately determines the time intervals of three types of commutation failure and the dynamic change characteristics of their respective valve-side currents, and accurately proposes effective detection criteria and structures. It has universal applicability to the detection of commutation failure in various DC engineering projects. Compared with actual engineering solutions and existing technologies, this invention has greater advantages in terms of detection reliability, sensitivity, and commutation failure type identification ability.

[0100] Please refer to Figure 1, which is a flowchart of a method for detecting commutation failures of high voltage DC systems adapted to multiple types, provided in Embodiment 1 of the present invention.

[0101] This invention provides a method for detecting commutation failures in high-voltage direct current systems adapted to various types, comprising:

[0102] Step 101: Respond to the commutation detection request of the target system and obtain the valve-side current waveform and commutation characteristic data of the target system.

[0103] The target system refers to the high-voltage direct current transmission system.

[0104] A commutation test request refers to a test request command initiated to check whether the commutation process in a high-voltage direct current transmission system is normal.

[0105] Valve-side current waveform: A curve showing the change of current flowing through the converter valve over time.

[0106] Commutation characteristic data refers to relevant data that can reflect the characteristics of the commutation process in the target system, including but not limited to steady-state commutation angle, steady-state trigger angle, steady-state trigger phase interval, first converter valve pre-contact angle and second converter valve pre-contact angle.

[0107] In this embodiment of the invention, in response to a received detection request command for whether the commutation process in the high voltage direct current transmission system is normal, the valve-side current waveform of the current flowing through the converter valve of the target system changes with time, and commutation characteristic data reflecting the characteristics of the commutation process in the target system are acquired.

[0108] Step 102: Determine the commutation result based on the valve-side current waveform and the preset commutation failure criterion.

[0109] The preset commutation failure criterion refers to obtaining the valve-side current waveform of the converter transformer in the event of a commutation failure by analyzing the valve-side current relationship of the transformer in the event of a commutation failure, and then analyzing the valve-side current waveform of the transformer in the event of a commutation failure to obtain an auxiliary criterion for the commutation failure.

[0110] In this embodiment of the invention, the valve-side current waveform of the target system is analyzed in real time based on the pre-analyzed commutation failure criterion, thereby obtaining the commutation result of the target system.

[0111] Step 103: When a commutation result is a commutation failure, the interval between two commutation failures is determined based on the commutation failure time and commutation characteristic data of the commutation failure.

[0112] The interval between two commutation failures refers to the time range during system operation where two commutation failures occur. This time range can be divided into two types based on the order and interval of the two commutation failures: the interval between two consecutive commutation failures and the interval between two discontinuous commutation failures.

[0113] The interval between two consecutive commutation failures refers to a situation in which two commutation failures occur in quick succession within a short period of time, without any successful commutation in between.

[0114] The interval between two discontinuous commutation failures refers to the situation where there is a successful commutation between two commutation failures.

[0115] In this embodiment of the invention, based on the commutation failure time of a single commutation failure and combined with commutation characteristic data, the intervals of two consecutive commutation failures and two discontinuous commutation failures are determined.

[0116] Step 104: Based on the two commutation failure intervals, valve-side current waveforms, and preset two commutation failure criteria, determine the two commutation results.

[0117] The pre-set commutation failure criterion refers to obtaining the valve-side current waveforms of the converter transformer after two commutation failures by analyzing the valve-side current relationship of the converter transformer after two commutation failures. Then, the valve-side current waveforms of the two commutation failures are analyzed to obtain auxiliary criteria for two commutation failures. There are two types: two consecutive commutation failure criteria and two discontinuous commutation failure criteria.

[0118] The criterion for two consecutive commutation failures refers to the basis or standard used to determine whether two consecutive commutation failures have occurred in a high-voltage direct current transmission system.

[0119] The criterion for two discontinuous commutation failures refers to the basis or standard used to determine whether two discontinuous commutation failures have occurred in a high-voltage direct current transmission system.

[0120] In this embodiment of the invention, the valve-side current waveform is analyzed based on the two commutation failure intervals and the preset two commutation failure criteria to obtain the two commutation results of the target system.

[0121] In this invention, in response to a commutation detection request for the target system, the valve-side current waveform and commutation characteristic data of the target system are acquired. Based on the valve-side current waveform and a preset first commutation failure criterion, a first commutation result is determined. When the first commutation result indicates a first commutation failure, the interval between two commutation failures is determined based on the commutation failure time and commutation characteristic data. Based on the interval between two commutation failures, the valve-side current waveform, and the preset two commutation failure criterion, the results of two commutations are determined. This invention first analyzes the valve-side current waveform of the target system using a pre-analyzed first commutation failure criterion to accurately obtain the first commutation result. Then, it determines the interval between two commutation failures based on the commutation failure time of the first commutation failure. Combining this with the pre-analyzed two commutation failure criterion, the results of two commutations are finally obtained. This invention can accurately identify the results of different types of commutation in a high-voltage direct current transmission system, accurately determine whether different commutation failure situations have occurred, and improve the operational stability of the high-voltage direct current transmission system.

[0122] Please refer to Figure 2, which is a flowchart of a multi-type high-voltage DC commutation failure detection method provided in Embodiment 2 of the present invention.

[0123] This invention provides a method for detecting commutation failures in high-voltage direct current systems adapted to various types, comprising:

[0124] Step 201: Respond to the commutation detection request of the target system and obtain the valve-side current waveform and commutation characteristic data of the target system.

[0125] In this embodiment of the invention, the specific implementation process of step 201 is similar to that of step 101, and will not be repeated here.

[0126] Furthermore, the pre-defined criteria for a single commutation failure include atypical commutation failure criteria and typical commutation failure criteria. The pre-defined criteria for two commutation failures include two consecutive commutation failure criteria and two discontinuous commutation failure criteria.

[0127] It is worth mentioning that this invention obtains the valve-side current relationship and waveform under various commutation failure types. By analyzing the valve-side current relationship of the converter transformer under one commutation failure, two consecutive commutation failures, and two discontinuous commutation failures, the valve-side current waveform under commutation failure is obtained. The following analysis focuses on converter valve V1. y To V3 y Commutation failure process:

[0128] (1) Obtain the valve-side current waveform during a single commutation failure.

[0129] Process 1: When u yba Located on the positive half-axis and V3 y When a trigger pulse signal is received, V1 y Start moving towards V3 y Commutation. V1 before i1 drops to 0. y V2 y and V3 y Simultaneously activated: i a +i b =-i c =-I d (1)

[0130] In the formula, L T i represents the commutation reactance referred to the valve side. a i b i c These represent the three-phase valve-side currents, flowing from the converter valves to the AC system, I. d Represents direct current, u yba This represents the commutation voltage.

[0131] Process 2: u yba When the negative crosses zero, V1 y If the circuit is not turned off or the remaining carriers are not exhausted after the circuit is turned off, V1 y It will continue or restart conduction due to the presence of a positive voltage, V3 y It begins to turn off when subjected to reverse voltage. yba From the negative zero crossing to V4 y Before conduction, the current relationship can still be expressed by formulas (1) and (2), but its initial value is different from that of process 1.

[0132] Process 3: V1 y To V3 y The phase switching process is not yet complete; V2 of the common anode group... y It has begun to move to V4 y Commutation, at this time V1 y V2 y V3 y and V4 y Simultaneously activated: i a +i b +i c =0 (3)

[0133] Process 4: V4 y Whether it is triggered early and the extent to which it is triggered early will affect V2. y and V3 y The order of shutdown.

[0134] Case 1: V4 y When triggered, V1 y To V3 y The commutation process is nearing completion, the i3 has been degraded for a long time, and the V3... y Before V2 y Off. V3 y After shutdown to V2 y Before shutdown, V1 y V2 y and V4 y Simultaneous conduction:

[0135] Case 2: V1 y To V3 y V4 in the early stages of commutation or even before commutation y It has already been triggered, V2 y Before V3 y Off. V2 y After shutting down to V3 y Before shutdown, V1 y V3 y and V4 y Simultaneous conduction:

[0136] Process 5: V1 only y and V4 y On, DC side short circuit: i a =i b =i c =0 (9)

[0137] According to V4 y The degree of early triggering can be used to obtain the valve-side current waveforms with two typical characteristics and one atypical characteristic of a single commutation failure, as shown in Figures 3-5.

[0138] Figure 3 is a schematic diagram of the valve-side current waveform, which is a typical feature of the first commutation failure.

[0139] Figure 4 is a schematic diagram of the valve-side current waveform of the second typical characteristic of a single commutation failure.

[0140] Figure 5 is a schematic diagram of the valve-side current waveform, which shows the atypical characteristics of a single commutation failure.

[0141] In the diagram, i s This represents the steady-state current; "on" indicates conduction, and "off" indicates deactivation. (U represents the steady-state current.) yba The positive zero-crossing phase is the reference phase "0". Normally, V3... y The trigger phase is 142°, V4 yThe trigger phase is 202°. In Figure 3, the trigger phase of V4y is 200°, indicating a very small degree of premature triggering; in Figure 4, V4... y The trigger phase is 180°, indicating a significant degree of premature triggering. (Figure 5 shows V4...) y The trigger phase is 189°, where V2 y and V3 y The phase interval between shutdowns is approximately 4°.

[0142] (2) Obtain the valve-side current waveform after two consecutive commutation failures.

[0143] Two consecutive commutation failures refer to two consecutive failures in V1. y To V3 y Based on the failure of commutation, V2 y To V4 y Commutation failure. Two consecutive commutation failures often develop from a single commutation failure in scenario 1 of step 4, with the following subsequent process:

[0144] Process 5: -u yac When the negative crosses zero, V2 y If the circuit is not turned off or the remaining carriers are not exhausted after the circuit is turned off, V2 y It will continue or restart conduction due to the presence of a positive voltage, V4 y It begins to shut down when subjected to reverse voltage:

[0145] Process 6: V6 y After conduction, V4 y and V5 y The following will be shut down sequentially: i a +i b +i c =0 (12)

[0146] Process 7: V5 y Shut down to V6 y Before shutdown, V1 at this time y V2 y and V6 y Simultaneously activated: i b +i c =-i a =I d (14)

[0147] Process 8: V6y is turned off, leaving only V1y and V2y conducting:

[0148] Figure 6 shows the valve-side current waveform after two consecutive commutation failures. Figure 6 is a schematic diagram of the valve-side current waveform after two consecutive commutation failures.

[0149] (3) Obtain the valve-side current waveforms after two discontinuous commutation failures.

[0150] Two discontinuous commutation failures refer to two instances of failure in V1. y To V3 y Based on the failure of commutation, V2 y To V4 y Successful phase change, V4 y To V6 y Commutation failure. Two discontinuous commutation failures often develop from a single commutation failure (case 1 of 4). The first commutation failure follows the same process as the first commutation failure, with the subsequent steps as follows:

[0151] Process 6: V1 y To V3 y The commutation forces V3 y After being turned off, V5 y The commutation voltage is determined by u ycb Change to u yca V5 y The conduction conditions are: (1) the potential at point c is higher than the potential at point a; (2) V5 y The trigger pulse has been generated:

[0152] Scenario 1: V5 y Conductive:

[0153] Scenario 2: V5 y Non-conductive: i a =i b =i c =0 (19)

[0154] Process 7: V6 y Turn on to V2 y Before conduction, V1 is at this time y V4 y and V6 y Simultaneous conduction:

[0155] Process 8: V2 y Is it in V6? y The effect of turning off the circuit before it is turned on on affects the subsequent commutation circuit:

[0156] Case 1: V1 y V2 y V4 y and V6 y Simultaneously activated: i a +i b +i c =0 (22)

[0157] Scenario 2: V6 y V2 before shutdown y Not conducting, only V1 y and V4 y Conductive, DC side short circuit.

[0158] Process 9: Regardless of the state of Process 8, it is V1 at this point. y V2 y and V4 y When the circuit is turned on, the current relationship is consistent with formulas (17) and (18).

[0159] Process 10: V1 only y and V4 y On, DC side short circuit: i a =i b =i c =0 (24)

[0160] Figure 7 shows the valve-side current waveforms after two discontinuous commutation failures. Figure 7 is a schematic diagram of the valve-side current waveforms after two discontinuous commutation failures.

[0161] Step 202: If the valve-side current waveform meets the atypical commutation failure criterion, then the target system is determined to have experienced an atypical commutation failure.

[0162] Based on the above process, the criteria for atypical commutation failure are obtained:

[0163] During a commutation failure with atypical characteristics, from V3 y When the bypass pair appears, i a The negative half-axis shows a trend of gradually increasing to 0, i b The negative half-axis exhibits a trend of first decaying to a minimum value and then increasing to 0. This constitutes an auxiliary criterion for a single commutation failure.

[0164] (1) The valve-side current of the AC phase connected to the converter valve that failed to shut off (referred to as "i") x The current value increases on the negative half-axis, and the increase is greater than the current threshold I1 (the preset first current threshold).

[0165] (2) The valve-side current of the AC phase connected to the converter valve that is forced to shut down (referred to as "i") y ", its lag i x A local minimum exists on the negative half-axis (phase 120°);

[0166] (3)i y After reaching a minimum value, the current increases, and the increase is greater than the current threshold I2 (the preset second current threshold).

[0167] Furthermore, step 202 may include the following sub-steps:

[0168] S11. Obtain the first phase valve-side current waveform and the second phase valve-side current waveform when the valve-side current is negative.

[0169] S12. Determine whether the current waveform on the valve side of the first phase has an increasing trend.

[0170] S13. When the current waveform on the first phase valve side shows an increasing trend, determine whether the increasing trend is greater than the preset first current threshold.

[0171] S14. When the increasing trend is greater than the preset first current threshold, it is determined that there is a first commutation failure feature.

[0172] S15. Determine whether the current waveform on the valve side of the second phase has a minimum value.

[0173] S16. If the current waveform on the valve side of the second phase has a minimum value, it is determined that there is a second commutation failure characteristic.

[0174] S17. Determine whether the increasing trend of the second phase valve side current waveform after the second phase valve side current waveform reaches its minimum value is greater than the preset second current threshold.

[0175] S18. When the increasing trend of the current waveform on the valve side of the second phase is greater than the preset second current threshold, it is determined that there is a third commutation failure feature.

[0176] S19. When the valve-side current waveform simultaneously exhibits the first commutation failure characteristic, the second commutation failure characteristic, and the third commutation failure characteristic, it is determined that the target system has experienced an atypical commutation failure.

[0177] For ease of understanding, please refer to Figures 8 and 9. The atypical commutation failure detection logic for steps S11-S19 is as follows:

[0178] Please refer to Figure 8, which shows the valve-side current i of the first phase valve-side current waveform. x A schematic diagram of the criterion logic;

[0179] Please refer to Figure 9, which shows the valve-side current i of the second phase valve-side current waveform. y A schematic diagram of the criterion logic;

[0180] In Figures 8-9, L incx and L incy These are reflections of i x and i y Whether the signal level is increasing, L decy It reflects i y Whether the signal level is attenuated, P incx and P incy These are reflections of L incx and L incy Rising edge pulse signal, irx and i ry They are i x and i y Incrementing initial value, L rx It is the level signal reflecting the auxiliary criterion (1), L miny It is the level signal reflecting the auxiliary criterion (2), L ry It reflects i y The level signal that meets the increasing requirement on the negative half-axis.

[0181] Please refer to Figure 8, i x The specific control steps for the judgment are as follows:

[0182] 1. Input the valve-side current of the converter transformer and determine whether it increases. If it increases, output an increasing signal.

[0183] 2. Detect the rising edge of the incrementing signal, and output a pulse signal when the rising edge arrives;

[0184] 3. Record the valve-side current i at the moment of the pulse signal. x The value is i rx ;

[0185] 4. Input i x with i rx The difference is used to determine whether it is greater than a threshold. If it is, a high-level signal is output.

[0186] 5. Determine i x If the value is less than 0, output a high-level signal.

[0187] 6. Perform a logical AND operation on the high-level signals in 4 and 5, and widen them to output the level signal of the auxiliary criterion (1).

[0188] Please refer to Figure 9, i y The specific control steps for the judgment are as follows:

[0189] 1. Input the valve-side current of the converter transformer and determine whether it is increasing or decreasing. If it is increasing, output an increasing signal; if it is decreasing, output a decreasing signal.

[0190] 2. Input an increasing signal and an decreasing signal to determine whether there is a minimum value in the valve-side current. If so, output a level signal and widen it to obtain a level signal L that reflects the auxiliary criterion (2). miny ;

[0191] 3. Detect the rising edge of the incrementing signal, and output a pulse signal when the rising edge arrives;

[0192] 4. Record the valve-side current i at the moment of the pulse signal. y The value is L ry ;

[0193] 5. Input i y With L ry The difference is used to determine whether it is greater than a threshold. If it is, a high-level signal is output.

[0194] 6. Determine i y If the value is less than 0, output a high-level signal.

[0195] 7. Perform a logical AND operation on the high-level signals in 4 and 5, widen the output, and reflect i. y The level signal L that meets the increment requirement on the negative half-axis ry .

[0196] In this embodiment of the invention, when i is detected x When the negative semi-axis increases and the increase is greater than the threshold, L rx Convert to high level; when i is detected y When a minimum point exists on the negative half-axis, L miny Convert to high level; when i is detected y When the negative half-axis increases and the increase is greater than the threshold, L ry Convert to high level; when L rx ,L miny and L ry When the signal is at a high level, the first atypical commutation failure is detected.

[0197] Step 203: When the valve-side current waveform meets the typical commutation failure criterion, it is determined that the target system has experienced a typical commutation failure.

[0198] Typical commutation failure criteria refer to the standards or bases used to determine whether a typical commutation failure has occurred in a high-voltage direct current transmission system.

[0199] It should be noted that the valve-side current waveform is one of the important bases for judging typical commutation failure. When a typical commutation failure occurs, the valve-side current waveform will show obvious abnormal characteristics.

[0200] In this embodiment of the invention, the valve-side current waveform of the target system is acquired in real time, and it is determined whether the commutation characteristics in the valve-side current waveform meet the commutation failure characteristics in the typical commutation failure criterion. The typical commutation failure criterion is obtained through the above-mentioned analysis of the valve-side current waveform during a single commutation failure.

[0201] The first typical commutation failure criterion:

[0202] 1) Valve-side current of the AC phase connected to the converter valve that failed to shut down (referred to as "i") x 1) It shows an increasing trend on the negative half-axis; 2) When it increases to near zero but less than zero, it begins to decay on the negative half-axis; 3) Then it quickly turns to increase again and eventually increases to zero on the negative half-axis.

[0203] The second typical commutation failure criterion:

[0204] 1) Valve-side current of the AC phase connected to the converter valve that failed to shut down (referred to as "i") x 1) It shows an increasing trend on the negative half-axis; 2) When it increases to near zero but less than zero, it crosses the zero value and rapidly increases to a certain value on the positive half-axis in a short period of time; 3) Then it quickly turns to decay and eventually decays to zero.

[0205] By using the two typical commutation failure criteria mentioned above, it can be determined whether the target system has experienced a typical commutation failure and the type of such failure. The typical commutation failure detection logic here is similar to the atypical commutation failure detection logic mentioned above, and will not be elaborated further here.

[0206] Step 204: If there is no atypical commutation failure or typical commutation failure, then the commutation result is determined as no commutation failure has occurred.

[0207] In this embodiment of the invention, when there is no atypical commutation failure or typical commutation failure, that is, when there is neither atypical commutation failure nor typical commutation failure, a commutation result is determined to be no commutation failure.

[0208] Step 205: When there is an atypical commutation failure or a typical commutation failure, the commutation result is determined as a commutation failure.

[0209] In this embodiment of the invention, when there is an atypical commutation failure or a typical commutation failure, that is, when there is either an atypical commutation failure or a typical commutation failure, then a commutation result is determined to be a commutation failure.

[0210] Step 206: When a commutation result is a commutation failure, the interval between two commutation failures is determined based on the commutation failure time and commutation characteristic data of the commutation failure.

[0211] Furthermore, the commutation characteristic data includes steady-state commutation angle, steady-state trigger angle, steady-state trigger phase interval, first converter valve pre-contact angle, and second converter valve pre-contact angle. The two commutation failure intervals include two consecutive commutation failure intervals and two discontinuous commutation failure intervals. Step 206 may include the following sub-steps:

[0212] S21. Using the commutation failure time and steady-state commutation angle, determine the lower limit of the interval between two consecutive commutation failures.

[0213] The lower limit of the interval between two consecutive commutation failures is encapsulated into a calculation formula, as follows:

[0214] In the formula, tconlower t represents the lower limit of the interval between two consecutive commutation failures. CF μ represents the moment of commutation failure. ref This represents the steady-state commutation angle, specifically 23°.

[0215] S22. Using the commutation failure time and steady-state trigger angle, determine the upper limit of the interval between two consecutive commutation failures.

[0216] The upper limit of the interval between two consecutive commutation failures is encapsulated into a calculation formula, as follows:

[0217] In the formula, t conupper α represents the upper limit of the interval between two consecutive commutation failures. ref This indicates the steady-state firing angle, specifically 142°.

[0218] In this embodiment of the invention, the time of occurrence of a commutation failure is determined by step 205. That is, when either atypical or typical commutation failure exists, the time corresponding to the first pulse signal emitted is the time of occurrence of a commutation failure, and the time of occurrence of a commutation failure is t. cf Considering the phase interval from the start to the end of the first commutation is 23°, and the time interval is 1.28ms, 1.28ms corresponds to 23°, and the steady-state commutation angle is 23°. Even if we optimistically assume that the commutation failure detection signal is issued at the very beginning of the first commutation, t cf At +0.00128s, the next converter valve has also been turned on. After the next converter valve is turned on, i x It shows an increasing trend. Conservatively assuming V6y did not trigger prematurely, then V6... y Conduction distance V1 y To V3 y The conservative phase interval at the commutation start point is 142°, corresponding to a time interval of 7.88ms. 7.88ms corresponds to 142°, and the steady-state firing angle is 142°. Therefore, t∈[t cf +0.00128s,t cf +0.00788s] can effectively distinguish between the first and second commutation failures without affecting the detection of the second commutation failure. In t∈[t cf +0.00128s,t cf Within the time interval of +0.00788s, if i is detected... x The existence of a maximum value necessarily means that the second commutation failure has occurred.

[0219] S23. Using the commutation failure time, steady-state firing angle, and the pre-contact angle of the first converter valve, determine the lower limit of the interval between two discontinuous commutation failures.

[0220] The lower limit of the interval between two discontinuous commutation failures is encapsulated into a calculation formula, as follows:

[0221] In the formula, tinconlower represents the lower limit of the interval between two discontinuous commutation failures, and Δα6 represents the pre-contact angle of the first converter valve, specifically V6. y The angle for early triggering is 30°.

[0222] S24. Using the commutation failure time, steady-state trigger phase interval, steady-state trigger angle, and the pre-contact angle of the second converter valve, determine the upper limit of the interval between two discontinuous commutation failures.

[0223] The upper limit of the interval between two discontinuous commutation failures is encapsulated into a calculation formula, as follows:

[0224] In the formula, t i nconupper This represents the upper limit of the interval between two discontinuous commutation failures. This indicates the steady-state trigger phase interval, specifically referring to the steady-state trigger phase interval of a 6-pulse converter, 60°. Δα2 represents the pre-contact angle of the second converter valve, specifically referring to V2. y The angle for early triggering is 40°, and 5 indicates V2. y Commutation voltage positive zero crossing point and V3 y There are 5 trigger phase intervals between the positive zero-crossing points of the commutation voltage.

[0225] In this embodiment of the invention, a conservative estimate is that the response delay of a single commutation failure detection signal is approximately 1.5ms, and that the control system typically generates the trigger pulse for the subsequent commutator valve in advance after a commutation failure. An optimistic estimate is made for V6. y If it is triggered 30° in advance, then V6 y The earliest possible conduction time is approximately 5ms after the first commutation failure detection signal is issued. This considered early trigger time margin will not cause false detections because, in the case of two discontinuous failures, the first bypass pair will appear up to V6. y Before being triggered, i a It is always non-negative.

[0226] Furthermore, without considering the commutation voltage phase shift, V6 y It begins to bear reverse voltage at a phase of 360°, at which point it is at a distance of V1. y To V3 y The time interval for the commutation start point is 10ms. V6 y When subjected to reverse voltage, i a The negative half-axis increases significantly from its minimum value.

[0227] Optimistically considering V2 y Triggered 40° in advance, i.e., V2 y If it conducts at a phase of 402°, then V2 y The trigger phase and V1 y To V3 y The phase interval at the commutation initiation point is 222°, corresponding to a time interval of 12.33 ms. Therefore, the time interval between the two discontinuous commutation failures is t∈[t cf +0.005s,t cf +0.01233s].

[0228] Please refer to Figure 10, which is a schematic diagram of obtaining the effect level in different time intervals of two commutation failures;

[0229] In the diagram, P CF and L CF These represent the detection pulse and the widened level for a single commutation failure, respectively. Time is the system runtime, and L... con It is a level signal reflecting the time interval between two consecutive commutation failures, L incon It is a level signal that reflects the time interval between two discontinuous commutation failures.

[0230] The specific control steps are as follows:

[0231] 1. Input the system running time and the pulse signal of a commutation failure. Sample the system running time. The sampled pulse is the pulse signal of a commutation failure. The sampled time is the time of the commutation failure.

[0232] 2. Send the time of one commutation failure to the module that calculates the upper and lower limits of the time interval, and output the upper and lower limits of the time intervals for two consecutive and two discontinuous commutation failures;

[0233] 3. Compare the time interval limit with the system running time, and output the time interval level of two consecutive commutation failures and the time interval level of two discontinuous commutation failures.

[0234] Step 207: Based on the two commutation failure intervals, the valve-side current waveform, and the preset two commutation failure criteria, determine the two commutation results.

[0235] Furthermore, the preset commutation failure criteria include two consecutive commutation failure criteria and two discontinuous commutation failure criteria. Step 207 may include the following sub-steps:

[0236] S31. Based on the intervals of two consecutive commutation failures, the valve-side current waveform, and the two consecutive commutation failure criteria, determine the results of the two consecutive commutations.

[0237] The criteria and structure for detecting two consecutive commutation failures are as follows:

[0238] The detection criteria for two consecutive commutation failures are:

[0239] (1) At t cf A commutation failure signal is detected at any time.

[0240] (2) In t∈[t cf +0.00128s,t cf Within the time interval of +0.00788s, i x The negative half-axis shows a trend of first increasing to the maximum point and then decreasing, with the decrease amplitude being greater than I3 (the preset third current threshold); 0.05kA is directly used to replace I3.

[0241] (3)i x +i z < ε, ε is slightly greater than 0. Where i z (The first phase valve-side current, in the transformed coordinate system, leads i) x Phase 120°.

[0242] i x i y i z These represent the three-phase currents on the valve side of the converter transformer. They are in relative transformed coordinates, for example: i x For i a i y For i b i z For i c i x For i b i y For i c i z For i a .

[0243] Furthermore, S31 may include the following sub-steps:

[0244] S311. When a commutation failure is detected, determine whether the running time of the target system is within the interval of two consecutive commutation failures.

[0245] S312. When the running time of the target system is within the interval of two consecutive commutation failures, it is determined that there is a fourth commutation failure feature.

[0246] S313. Determine whether the current waveform on the valve side of the first phase has an increasing trend.

[0247] S314. When the current waveform on the valve side of the first phase shows an increasing trend, determine whether the current waveform on the valve side of the first phase has a maximum value.

[0248] S315. When the current waveform on the valve side of the first phase has a maximum value, determine whether there is a decay trend after the increasing trend of the current waveform on the valve side of the first phase reaches the maximum value.

[0249] S316. When the increasing trend of the current waveform on the valve side of the first phase reaches its maximum value and then shows a decaying trend, it is determined that there is a fifth commutation failure characteristic.

[0250] S317. Determine whether the attenuation trend is greater than the preset third current threshold.

[0251] S318. When the attenuation trend is greater than the preset third current threshold, it is determined that there is a sixth commutation failure feature.

[0252] S319. Obtain the first phase valve side current waveform. The first phase valve side current is the first transformed phase valve side current under the transformed coordinate.

[0253] S3110. The sum of the first phase valve side current and the first transformation phase valve side current is used to generate the first sum.

[0254] S3111. Determine whether the first sum is less than the preset first sum threshold.

[0255] S3112. When the first sum is less than the preset first sum threshold, it is determined that there is a seventh commutation failure feature.

[0256] S3113. If the valve-side current waveform does not simultaneously exhibit the fourth, fifth, sixth, and seventh commutation failure characteristics, then it is determined that the target system has not experienced two consecutive commutation failures, and the eighth commutation failure characteristic is identified.

[0257] S3114. When the valve-side current waveform simultaneously exhibits the fourth, fifth, sixth, and seventh commutation failure characteristics, it is determined that the target system has experienced two consecutive commutation failures.

[0258] For ease of understanding, please refer to Figures 11-12. The logic for the two consecutive commutation detection steps S311-S3114 is as follows:

[0259] In the diagram, L decx It reflects i x Whether the signal level is attenuated, P decx It reflects L decx Rising edge pulse signal, L dx It reflects i x Does the signal level meet the attenuation requirement on the negative half-axis? dx is i x The initial value of the decay, L maxx It reflects i xDoes a level signal with a maximum value exist, L? subcon It reflects i x +i z <ε level signal, L CFcon It is a detection signal indicating two consecutive commutation failures.

[0260] Figure 11 shows the valve-side current waveform of the first phase, i. x A schematic diagram of the attenuation criterion;

[0261] Figure 12 is a schematic diagram of the acquisition of detection signals for two consecutive commutation failures;

[0262] Please refer to Figure 11. The specific control steps for the attenuation criterion are as follows:

[0263] 1. Input the valve-side current of the converter transformer, determine whether it is attenuated, and if it is attenuated, output an attenuation signal;

[0264] 2. Detect the rising edge of the attenuation signal, and output a pulse signal when the rising edge arrives;

[0265] 3. Record the valve-side current i at the moment of the pulse signal. x The value is i dx ;

[0266] 4. Input i dx with i x The difference is used to determine whether it is greater than a threshold. If it is, a high-level signal is output.

[0267] 5. Determine i x If the value is less than 0, output a high-level signal.

[0268] 6. Perform a logical AND operation on the high-level signals in 4 and 5, widen the output, and reflect i. x Attenuated level signal L dx .

[0269] Please refer to Figure 12 for the specific control steps for acquiring the detection signals of two consecutive commutation failures:

[0270] 1. Input the valve-side current of the converter transformer and determine whether it is increasing or decreasing. If it is increasing, output an increasing signal; if it is decreasing, output a decreasing signal.

[0271] 2. Input the attenuated signal and the broadened increasing signal. Through a logical AND operation, if the two signals have a high-level intersection, the output reflects i. x Level signal L with a maximum value maxx ;

[0272] 3. Determine i x with i zIf the modulus of the sum is less than the threshold, output the level signal L that reflects the detection criterion (3) for two consecutive commutation failures. subcon ;

[0273] 4. Enter L maxx L subcon , reflecting i x Attenuated level signal L dx The effective level L during the time interval of two consecutive commutation failures con The four signals are ANDed together. If a high-level intersection is found among the four signals, a detection signal L indicating two failed commutations is output. CFcon .

[0274] In this embodiment of the invention, when the first commutation failure is detected and Time falls within the time interval of two consecutive commutation failures, L con Convert to high level; when i is detected x When the negative half-axis exhibits a characteristic of first increasing to a maximum value and then decaying, L maxx Convert to high level; when i is detected x When the attenuation amplitude of the negative half-axis is greater than the threshold, L dx Convert to high level; when i is detected x +i z When L < ε subcon Convert to high level; when L con ,L maxx ,L dx and L subcon When L is at a high level, CFcon A switch to a high level indicates that two consecutive commutation failures have been detected.

[0275] S32. Based on the two consecutive commutation failure intervals, the two discontinuous commutation failure intervals, the valve-side current waveform, and the two discontinuous commutation failure criteria, determine the results of the two discontinuous commutation failures.

[0276] Criteria and structure for detecting two discontinuous commutation failures:

[0277] The detection criteria for two discontinuous commutation failures are as follows:

[0278] (1) At t cf A commutation failure signal is detected at any time.

[0279] (2) During the time interval t∈[t] of the two consecutive commutation failures cf +0.00128s,t cf Within +0.00788s, no two consecutive commutation failure signals were detected;

[0280] (3) In t∈[t cf +0.005s,tcf Within the time interval [+0.01233s], i x The negative half-axis shows a trend of first decaying to a minimum point and then increasing significantly.

[0281] (4)i x +i y <ε, ε is slightly greater than 0.

[0282] Furthermore, S32 may include the following sub-steps:

[0283] S321. When a commutation failure is detected, determine whether the running time of the target system is within the interval of two discontinuous commutation failures.

[0284] S322. When the running time of the target system is within the interval of two discontinuous commutation failures, it is determined that there is a ninth commutation failure feature.

[0285] S323. Determine whether the current waveform on the valve side of the first phase has a decay trend.

[0286] S324. When the current waveform on the valve side of the first phase has a decaying trend, determine whether there is an increasing trend after the decaying trend of the current waveform on the valve side of the first phase reaches a minimum value.

[0287] S325. When the attenuation trend of the current waveform on the valve side of the first phase reaches a minimum value and then shows an increasing trend, it is determined that there is a tenth commutation failure characteristic.

[0288] S326. Determine whether the increasing trend is greater than the preset fourth current threshold.

[0289] S327. When the increasing trend is greater than the preset fourth current threshold, it is determined that there is an eleventh commutation failure feature.

[0290] S328. The sum of the first phase valve-side current and the second phase valve-side current of the first phase valve-side current waveform and the second phase valve-side current waveform is used to generate a second sum.

[0291] S329. Determine whether the second sum is less than the preset second sum threshold.

[0292] S3210. When the second sum is less than the preset second sum threshold, it is determined that there is a twelfth commutation failure feature.

[0293] S3211. If the valve-side current waveform does not simultaneously exhibit the ninth, tenth, eleventh, and twelfth commutation failure characteristics, or if the eighth commutation failure characteristic is present, then it is determined that the target system has not experienced two discontinuous commutation failures.

[0294] S3212. When the valve-side current waveform simultaneously exhibits the ninth, tenth, eleventh, and twelfth commutation failure characteristics, and does not exhibit the eighth commutation failure characteristic, it is determined that the target system has experienced two discontinuous commutation failures.

[0295] For ease of understanding, please refer to Figure 13. The logic for the two discontinuous commutation detection steps S321-S3212 is as follows:

[0296] Figure 13 is a schematic diagram of the acquisition of detection signals for two discontinuous commutation failures;

[0297] In the diagram, L minx It reflects i x Does a minimum level signal exist, L? subincon It reflects i x +i y <ε level signal, L CFincon It is a detection signal indicating two discontinuous commutation failures.

[0298] The specific control steps for acquiring the detection signals of two discontinuous commutation failures are as follows:

[0299] 1. Input the valve-side current of the converter transformer and determine whether it is increasing or decreasing. If it is increasing, output an increasing signal; if it is decreasing, output a decreasing signal.

[0300] 2. Input an incrementing signal and a broadened attenuated signal. Through a logical AND operation, if the two signals have a high-level intersection, the output reflects i. x Level signal L with a minimum value minx ;

[0301] 3. Determine i x with i y If the modulus of the sum is less than the threshold, output the level signal L that reflects the detection criterion (4) for two discontinuous commutation failures. subincon ;

[0302] 4. Enter L minx L subincon , reflecting i x Increasing level signal L rx The effective level L during the time interval of two discontinuous commutation failures CFincon The four signals are ANDed together. If there is a high-level intersection among the four signals, a high-level signal is output.

[0303] 5. Input the detection signal for two failed commutations, widen it, invert it, and then AND it with the output signal from step 4. If the two signals have a high-level intersection, output the detection signal L reflecting two failed commutations. CFincon .

[0304] In this embodiment of the invention, when the first commutation failure is detected and Time belongs to the time interval of two discontinuous commutation failures, L incon Convert to high level; when i is detected x When the negative half-axis exhibits a characteristic of first decaying to a minimum and then increasing, L minx Convert to high level; when i is detected x When the increment of the negative half-axis is greater than the threshold, L rx Convert to high level; when i is detected x +i y When L < ε subincon Switches to high level. When L incon ,L minx ,L rx and L subincon Simultaneously at high level and L CFcon When L is at a low level CFincon A switch to a high level indicates that two discontinuous commutation failures have been detected.

[0305] In this invention, in response to a commutation detection request for the target system, the valve-side current waveform and commutation characteristic data of the target system are acquired. Based on the valve-side current waveform and a preset first commutation failure criterion, a first commutation result is determined. When the first commutation result indicates a first commutation failure, the interval between two commutation failures is determined based on the commutation failure time and commutation characteristic data. Based on the interval between two commutation failures, the valve-side current waveform, and the preset two commutation failure criterion, the results of two commutations are determined. This invention first analyzes the valve-side current waveform of the target system using a pre-analyzed first commutation failure criterion to accurately obtain the first commutation result. Then, it determines the interval between two commutation failures based on the commutation failure time of the first commutation failure. Combining this with the pre-analyzed two commutation failure criterion, the results of two commutations are finally obtained. This invention can accurately identify the results of different types of commutation in a high-voltage direct current transmission system, accurately determine whether different commutation failure situations have occurred, and improve the operational stability of the high-voltage direct current transmission system.

[0306] The following provides specific simulation verification examples:

[0307] 1. Simulation Verification of DC Engineering Model 1

[0308] Simulation Scenario 1: When the system runs for 3.992s, a three-phase ground fault with a fault inductance of 0.04H and a duration of 0.1s occurs in the AC system. The response of the commutation failure detection loop is shown in Figure 14. Figure 14 is a schematic diagram of the commutation failure detection loop response under a three-phase fault in DC engineering model 1.

[0309] Simulation Scenario 2: When the system has been running for 4 seconds, a ground fault with an inductance of 0.01H occurs in phase A and lasts for 0.1 seconds. The response of the commutation failure detection circuit is shown in Figure 15. Figure 15 is a schematic diagram of the commutation failure detection circuit response when phase A is faulty in DC engineering model 1.

[0310] Where i Y and i D These represent the valve-side currents of the YNy0 and YNd1 type converter transformers, respectively. Level = 1 indicates that the commutation failure detection circuit has been activated. CF ,L SCF_con and L SCF_in L represents the output signals of the detection circuit for one, two consecutive, and two discontinuous commutation failures, respectively. CF_0 This represents the detection signal used in the actual engineering project. L CF L SCF_con L CF_0

[0311] Table 1 summarizes the trigger phase of the relevant valves in Figures 14 and 15, the response time of commutation failure detection within the first power frequency cycle after an AC fault, and the determination results of this invention. The relevant valve refers to the first valve after the forced shut-off valve, and its phase reference point is the positive zero-crossing point of the commutation voltage of the forced shut-off valve.

[0312] Combining Figures 14 and 15 with Table 1, in DC engineering model 1, regardless of whether it is a three-phase fault or a single-phase fault, the response time of the present invention for detecting commutation failure is significantly faster than that of the actual engineering scheme, and the present invention can accurately identify the type of commutation failure.

[0313] Table 1. Commutation failure information for DC engineering model 1

[0314] 2. Simulation Verification of DC Engineering Model 2

[0315] Simulation Case 3: When the system runs for 7.9933s, a ground fault with an inductance of 0.04H occurs in phase C and lasts for 0.1s. The response of the commutation failure detection circuit is shown in Figure 16. Figure 16 is a schematic diagram of the commutation failure detection circuit response when a phase C fault occurs in DC engineering model 2.

[0316] Simulation Scenario 4: When the system runs for 8 seconds, a three-phase ground fault with a fault inductance of 0.07H occurs in the AC system and lasts for 0.1 seconds. The response of the commutation failure detection loop is shown in Figure 17. Figure 17 is a schematic diagram of the commutation failure detection loop response under a three-phase fault in DC engineering model 2.

[0317] Simulation Scenario 5: When the system has been running for 8 seconds, a ground fault with an inductance of 0.02H occurs in phase A and lasts for 0.1 seconds. The response of the commutation failure detection circuit is shown in Figure 18. Figure 18 is a schematic diagram of the commutation failure detection circuit response when phase A is faulty in DC engineering model 2.

[0318] Among them, L CF_1 and L CF_2 L represents the detection signals of prior art features 1 and 2, respectively. CF_s This indicates the detection signal of the auxiliary detection stage for a single commutation failure in this invention.

[0319] In Figure 16, the existing technology does not operate, while the auxiliary detection stage for commutation failure of the present invention can operate reliably. In Figures 17 and 18, the present invention can accurately identify the type of commutation failure. Table 2 summarizes the relevant valve trigger phases in Figures 16 to 18, the response time of commutation failure detection within the first power frequency cycle after the occurrence of AC fault, and the judgment results of the present invention.

[0320] Combining Figures 16-18 and Table 2, in DC engineering model 2, the present invention can solve the problem of non-operation under atypical single commutation failure characteristics of the prior art. At the same time, the response speed of the present invention is no slower than that of the actual engineering scheme in most cases, and solves the problem that the actual engineering scheme cannot identify the type of commutation failure.

[0321] Table 2. Commutation failure information for DC engineering model 2

[0322] It should be noted that in Figures 14-18, the vertical axis "Level" represents the degree of response.

[0323] Please refer to Figure 19, which is a structural block diagram of a multi-type high-voltage DC commutation failure detection system provided in Embodiment 3 of the present invention.

[0324] This invention provides a multi-type high-voltage DC commutation failure detection system, comprising:

[0325] The response module 301 is used to respond to the commutation detection request of the target system and acquire the valve-side current waveform and commutation characteristic data of the target system; the single commutation determination module 302 is used to determine the single commutation result based on the valve-side current waveform and the preset single commutation failure criterion; the interval determination module 303 is used to determine the interval between two commutation failures based on the commutation failure time and commutation characteristic data when the single commutation result is a single commutation failure; the two commutation determination module 304 is used to determine the two commutation results based on the two commutation failure intervals, the valve-side current waveform and the preset two commutation failure criterion.

[0326] Furthermore, the preset commutation failure criteria include atypical commutation failure criteria and typical commutation failure criteria. The commutation determination module 302 includes: an atypical commutation failure submodule, used to determine that the target system has experienced atypical commutation failure when the valve-side current waveform meets the atypical commutation failure criteria; a typical commutation failure submodule, used to determine that the target system has experienced typical commutation failure when the valve-side current waveform meets the typical commutation failure criteria; a first determination submodule, used to determine that the commutation result is no commutation failure when there is no atypical commutation failure or typical commutation failure; and a second determination submodule, used to determine that the commutation result is a commutation failure when there is an atypical commutation failure or typical commutation failure.

[0327] Furthermore, the atypical commutation failure submodule includes: a waveform acquisition unit, used to acquire the first-phase valve-side current waveform and the second-phase valve-side current waveform when the valve-side current is negative; a first judgment unit, used to determine whether the first-phase valve-side current waveform has an increasing trend; a second judgment unit, used to determine whether the increasing trend is greater than a preset first current threshold when the first-phase valve-side current waveform has an increasing trend; a third judgment unit, used to determine that a first commutation failure characteristic exists when the increasing trend is greater than the preset first current threshold; and a fourth judgment unit, used to determine whether the second-phase valve-side current waveform has a minimum value. The fifth judgment unit is used to determine the existence of a second commutation failure feature when the valve-side current waveform of the second phase has a minimum value; the sixth judgment unit is used to determine whether the increasing trend of the valve-side current waveform of the second phase after reaching a minimum value is greater than a preset second current threshold; the seventh judgment unit is used to determine the existence of a third commutation failure feature when the increasing trend of the valve-side current waveform of the second phase is greater than a preset second current threshold; the eighth judgment unit is used to determine that an atypical commutation failure has occurred in the target system when the valve-side current waveform simultaneously exhibits the first commutation failure feature, the second commutation failure feature, and the third commutation failure feature.

[0328] Furthermore, the commutation characteristic data includes steady-state commutation angle, steady-state trigger angle, steady-state trigger phase interval, first converter valve pre-contact angle, and second converter valve pre-contact angle. The two commutation failure intervals include two consecutive commutation failure intervals and two discontinuous commutation failure intervals. The interval determination module 303 includes: a first lower limit submodule, used to determine the lower limit value of the two consecutive commutation failure intervals using the commutation failure time and steady-state commutation angle; a first upper limit submodule, used to determine the upper limit value of the two consecutive commutation failure intervals using the commutation failure time and steady-state trigger angle; a second lower limit submodule, used to determine the lower limit value of the two discontinuous commutation failure intervals using the commutation failure time, steady-state trigger angle, and first converter valve pre-contact angle; and a second upper limit submodule, used to determine the upper limit value of the two discontinuous commutation failure intervals using the commutation failure time, steady-state trigger phase interval, steady-state trigger angle, and second converter valve pre-contact angle.

[0329] Furthermore, the preset two-phase-commutation-failure criteria include two consecutive-phase-commutation-failure criteria and two discontinuous-phase-commutation-failure criteria. The two-phase-commutation-determination module 304 includes: a two-consecutive-phase-commutation-result submodule, used to determine the two-consecutive-phase-commutation-result based on the two-consecutive-phase-failure intervals, the valve-side current waveform, and the two-consecutive-phase-failure criteria; and a two-discontinuous-phase-commutation-result submodule, used to determine the two-discontinuous-phase-commutation-result based on the two-consecutive-phase-failure intervals, the two-discontinuous-phase-commutation-failure intervals, the valve-side current waveform, and the two-discontinuous-phase-commutation-failure criteria.

[0330] Furthermore, the two consecutive commutation result submodule includes: a first continuous processing unit, used to determine whether the running time of the target system is within the interval of two consecutive commutation failures when a commutation failure is detected; a second continuous processing unit, used to determine the existence of a fourth commutation failure feature when the running time of the target system is within the interval of two consecutive commutation failures; a third continuous processing unit, used to determine whether there is an increasing trend in the first phase valve-side current waveform; a fourth continuous processing unit, used to determine whether there is a maximum value in the first phase valve-side current waveform when there is an increasing trend; a fifth continuous processing unit, used to determine whether there is a decaying trend after the increasing trend of the first phase valve-side current waveform reaches its maximum value when there is a maximum value; a sixth continuous processing unit, used to determine the existence of a fifth commutation failure feature when there is a decaying trend after the increasing trend of the first phase valve-side current waveform reaches its maximum value; a seventh continuous processing unit, used to determine whether the decaying trend is greater than a preset third current threshold; and an eighth continuous processing unit, used to determine whether the decaying trend is greater than a preset third current threshold. If a sixth commutation failure feature is found to exist at a preset third current threshold, the ninth continuous processing unit is used to acquire the first phase valve-side current of the first phase valve-side current waveform under the transformed coordinates; the tenth continuous processing unit is used to perform a sum operation on the first phase valve-side current and the first transformed phase valve-side current to generate a first sum; the eleventh continuous processing unit is used to determine whether the first sum is less than a preset first sum threshold; the twelfth continuous processing unit is used to determine that a seventh commutation failure feature exists when the first sum is less than the preset first sum threshold; the first continuous determination unit is used to determine that the target system has not experienced two consecutive commutation failures and to determine that an eighth commutation failure feature exists when the valve-side current waveform does not simultaneously exhibit the fourth, fifth, sixth, and seventh commutation failure features; the second continuous determination unit is used to determine that the target system has experienced two consecutive commutation failures when the valve-side current waveform simultaneously exhibits the fourth, fifth, sixth, and seventh commutation failure features.

[0331] Furthermore, the two discontinuous commutation result submodule includes: a first discontinuity processing unit, used to determine whether the operating time of the target system is within the interval between two discontinuous commutation failures when a commutation failure is detected; a second discontinuity processing unit, used to determine that a ninth commutation failure feature exists when the operating time of the target system is within the interval between two discontinuous commutation failures; a third discontinuity processing unit, used to determine whether there is a decay trend in the first phase valve-side current waveform; a fourth discontinuity processing unit, used to determine whether there is an increasing trend after the decay trend of the first phase valve-side current waveform reaches a minimum value when there is a decay trend; a fifth discontinuity processing unit, used to determine that a tenth commutation failure feature exists when the decay trend of the first phase valve-side current waveform reaches a minimum value and there is an increasing trend; a sixth discontinuity processing unit, used to determine whether the increasing trend is greater than a preset fourth current threshold; and a seventh discontinuity processing unit, used to determine whether a tenth commutation failure feature exists when the increasing trend is greater than a preset fourth current threshold. The system includes: an eleventh commutation failure feature; an eighth discontinuity processing unit, used to perform a summation operation on the first phase valve-side current waveform of the first phase valve-side current and the second phase valve-side current waveform of the second phase valve-side current to generate a second sum; a ninth discontinuity processing unit, used to determine whether the second sum is less than a preset second sum threshold; a tenth discontinuity processing unit, used to determine that a twelfth commutation failure feature exists when the second sum is less than the preset second sum threshold; a third continuity determination unit, used to determine that the target system has not experienced two discontinuous commutation failures when the valve-side current waveform does not simultaneously exhibit the ninth, tenth, eleventh, and twelfth commutation failure features, or exhibits the eighth commutation failure feature; and a fourth continuity determination unit, used to determine that the target system has experienced two discontinuous commutation failures when the valve-side current waveform simultaneously exhibits the ninth, tenth, eleventh, and twelfth commutation failure features, and does not exhibit the eighth commutation failure feature.

[0332] In this invention, in response to a commutation detection request for the target system, the valve-side current waveform and commutation characteristic data of the target system are acquired. Based on the valve-side current waveform and a preset first commutation failure criterion, a first commutation result is determined. When the first commutation result indicates a first commutation failure, the interval between two commutation failures is determined based on the commutation failure time and commutation characteristic data. Based on the interval between two commutation failures, the valve-side current waveform, and the preset two commutation failure criterion, the results of two commutations are determined. This invention first analyzes the valve-side current waveform of the target system using a pre-analyzed first commutation failure criterion to accurately obtain the first commutation result. Then, it determines the interval between two commutation failures based on the commutation failure time of the first commutation failure. Combining this with the pre-analyzed two commutation failure criterion, the results of two commutations are finally obtained. This invention can accurately identify the results of different types of commutation in a high-voltage direct current transmission system, accurately determine whether different commutation failure situations have occurred, and improve the operational stability of the high-voltage direct current transmission system.

[0333] Please refer to Figure 20, which is a structural block diagram of a computer device provided in Embodiment 4 of the present invention.

[0334] An electronic device according to an embodiment of the present invention includes: a memory 401 and a processor 402. The memory 402 stores a computer program. When the computer program is executed by the processor 402, the processor 402 executes a high-voltage DC commutation failure detection method adapted to multiple types as described in any of the above embodiments.

[0335] Memory 401 may be an electronic memory such as flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), EPROM, hard disk, or ROM. Memory 401 has storage space 403 for program code 413 for performing any of the method steps described above. For example, storage space 403 for program code may include individual program codes 413 for implementing the various steps in the methods described above. This program code can be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, CDs, memory cards, or floppy disks. The program code may be compressed, for example, in a suitable form. When run by a computing processing device, this code causes the computing processing device to perform the various steps in the methods described above. This program code can be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, CDs, memory cards, or floppy disks. The program code may be compressed, for example, in a suitable form. When this code is run by a computing device, it causes the computing device to perform the various steps in the adaptive multi-type high-voltage DC commutation failure detection method described above.

[0336] Embodiment 5 of the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the adaptive multi-type high-voltage DC commutation failure detection method as described in any of the above embodiments.

[0337] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0338] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between apparatuses or units, and may be electrical, mechanical, or other forms.

[0339] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0340] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0341] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0342] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting commutation failures in high-voltage direct current systems adapted to multiple types, characterized in that, include: In response to a commutation detection request for the target system, the valve-side current waveform and commutation characteristic data of the target system are acquired; Based on the valve-side current waveform and the preset first commutation failure criterion, the first commutation result is determined; When the result of a single commutation is a commutation failure, the interval between two commutation failures is determined based on the commutation failure time and the commutation characteristic data. Based on the two commutation failure intervals, the valve-side current waveform, and the preset two commutation failure criteria, the two commutation results are determined.

2. The method for detecting multiple types of high-voltage DC commutation failures according to claim 1, characterized in that, The preset first-phase commutation failure criterion includes atypical commutation failure criteria and typical commutation failure criteria. The step of determining the first-phase commutation result based on the valve-side current waveform and the preset first-phase commutation failure criterion includes: If the valve-side current waveform satisfies the atypical commutation failure criterion, then the target system is determined to have experienced an atypical commutation failure. If the valve-side current waveform satisfies the typical commutation failure criterion, then the target system is determined to have experienced a typical commutation failure. If there is no atypical commutation failure or no typical commutation failure, then a commutation result is determined as no commutation failure has occurred. When either the atypical commutation failure or the typical commutation failure exists, a commutation result is determined to be a commutation failure.

3. The method for detecting multiple types of high-voltage DC commutation failures according to claim 2, characterized in that, The step of determining that the target system has experienced an atypical commutation failure when the valve-side current waveform satisfies the atypical commutation failure criterion includes: Obtain the first phase valve-side current waveform and the second phase valve-side current waveform when the valve-side current is negative. Determine whether the current waveform on the valve side of the first phase has an increasing trend; If the current waveform on the first phase valve side shows an increasing trend, then determine whether the increasing trend is greater than a preset first current threshold. If the increasing trend is greater than the preset first current threshold, it is determined that there is a first commutation failure feature; Determine whether the current waveform on the second phase valve side has a minimum value; If the current waveform on the valve side of the second phase has a minimum value, it is determined that there is a second commutation failure characteristic. After the second phase valve side current waveform reaches the minimum value, determine whether the increasing trend of the second phase valve side current waveform is greater than the preset second current threshold. If the increasing trend of the current waveform on the valve side of the second phase is greater than the preset second current threshold, it is determined that there is a third commutation failure feature. If the valve-side current waveform simultaneously exhibits the first commutation failure characteristic, the second commutation failure characteristic, and the third commutation failure characteristic, then the target system is determined to have experienced an atypical commutation failure.

4. The method for detecting multiple types of high-voltage DC commutation failures according to claim 3, characterized in that, The commutation characteristic data includes steady-state commutation angle, steady-state trigger angle, steady-state trigger phase interval, first converter valve pre-contact angle, and second converter valve pre-contact angle. The two commutation failure intervals include two consecutive commutation failure intervals and two discontinuous commutation failure intervals. Determining the two commutation failure intervals based on the commutation failure time of one commutation failure and the commutation characteristic data includes: Using the commutation failure time and the steady-state commutation angle, the lower limit of the interval between the two consecutive commutation failures is determined; Using the commutation failure time and the steady-state firing angle, the upper limit of the interval between the two consecutive commutation failures is determined; The lower limit of the interval between the two discontinuous commutation failures is determined by using the commutation failure time, the steady-state trigger angle, and the pre-contact angle of the first converter valve. The upper limit of the interval between the two discontinuous commutation failures is determined by using the commutation failure time, the steady-state trigger phase interval, the steady-state trigger angle, and the pre-contact angle of the second converter valve.

5. The method for detecting multiple types of high-voltage DC commutation failures according to claim 4, characterized in that, The preset two-phase-failure criteria include two consecutive commutation failure criteria and two discontinuous commutation failure criteria. Determining the two commutation results based on the two commutation failure intervals, the valve-side current waveform, and the preset two-phase-failure criteria includes: Based on the two consecutive commutation failure intervals, the valve-side current waveform, and the two consecutive commutation failure criteria, the results of the two consecutive commutations are determined. Based on the two consecutive commutation failure intervals, the two discontinuous commutation failure intervals, the valve-side current waveform, and the two discontinuous commutation failure criteria, the results of the two discontinuous commutation failures are determined.

6. The method for detecting multiple types of high-voltage DC commutation failures according to claim 5, characterized in that, The determination of the two consecutive commutation results based on the two consecutive commutation failure intervals, the valve-side current waveform, and the two consecutive commutation failure criteria includes: When a commutation failure is detected, it is determined whether the running time of the target system is within the interval between two consecutive commutation failures; If the running time of the target system is within the interval of the two consecutive commutation failures, then it is determined that there is a fourth commutation failure feature. Determine whether the current waveform on the valve side of the first phase has an increasing trend; If the current waveform on the first phase valve side shows an increasing trend, then determine whether the current waveform on the first phase valve side has a maximum value. If the current waveform on the first phase valve side has a maximum value, then determine whether the increasing trend of the current waveform on the first phase valve side has a decay trend after reaching the maximum value. When the increasing trend of the current waveform on the valve side of the first phase reaches its maximum value and then shows a decaying trend, it is determined that there is a fifth commutation failure characteristic. Determine whether the attenuation trend is greater than a preset third current threshold; If the attenuation trend is greater than the preset third current threshold, it is determined that there is a sixth commutation failure feature; The first phase valve-side current, obtained from the waveform of the first phase valve-side current, is the first transformed phase valve-side current in the transformed coordinate system. The first sum is generated by summing the current on the first phase valve side and the current on the first changing phase valve side. Determine whether the first sum is less than a preset first sum threshold; If the first sum is less than the preset first sum threshold, then a seventh commutation failure feature is determined to exist. If the valve-side current waveform does not simultaneously exhibit the fourth commutation failure feature, the fifth commutation failure feature, the sixth commutation failure feature, and the seventh commutation failure feature, then it is determined that the target system has not experienced two consecutive commutation failures, and it is determined that an eighth commutation failure feature exists. If the valve-side current waveform simultaneously exhibits the fourth commutation failure characteristic, the fifth commutation failure characteristic, the sixth commutation failure characteristic, and the seventh commutation failure characteristic, then it is determined that the target system has experienced two consecutive commutation failures.

7. The method for detecting multiple types of high-voltage DC commutation failures according to claim 6, characterized in that, The determination of the two discontinuous commutation results based on the two consecutive commutation failure intervals, the two discontinuous commutation failure intervals, the valve-side current waveform, and the two discontinuous commutation failure criteria includes: When a commutation failure is detected, it is determined whether the running time of the target system is within the interval between the two discontinuous commutation failures. If the running time of the target system is within the interval between the two discontinuous commutation failures, then it is determined that there is a ninth commutation failure feature. Determine whether the current waveform on the first phase valve side exhibits a decay trend; If the current waveform on the first phase valve side has a decaying trend, then determine whether there is an increasing trend after the decaying trend of the current waveform on the first phase valve side reaches a minimum value. If the attenuation trend of the current waveform on the valve side of the first phase reaches a minimum value and then shows an increasing trend, it is determined that there is a tenth commutation failure feature. Determine whether the increasing trend is greater than a preset fourth current threshold; If the increasing trend is greater than the preset fourth current threshold, it is determined that there is an eleventh commutation failure feature. A second sum is generated by summing the first phase valve-side current from the first phase valve-side current waveform and the second phase valve-side current from the second phase valve-side current waveform. Determine whether the second sum is less than a preset second sum threshold; If the second sum is less than the preset second sum threshold, then the twelfth commutation failure feature is determined to exist; If the valve-side current waveform does not simultaneously exhibit the ninth commutation failure feature, the tenth commutation failure feature, the eleventh commutation failure feature, and the twelfth commutation failure feature, or if the eighth commutation failure feature is present, then it is determined that the target system has not experienced two discontinuous commutation failures. If the valve-side current waveform simultaneously exhibits the ninth commutation failure feature, the tenth commutation failure feature, the eleventh commutation failure feature, and the twelfth commutation failure feature, and does not exhibit the eighth commutation failure feature, then the target system is determined to have experienced two discontinuous commutation failures.

8. A high-voltage DC commutation failure detection system adaptable to multiple types, characterized in that, include: The response module is used to respond to the commutation detection request of the target system and acquire the valve-side current waveform and commutation characteristic data of the target system. A single commutation determination module is used to determine the single commutation result based on the valve-side current waveform and a preset single commutation failure criterion. The interval determination module is used to determine the interval between two commutation failures based on the commutation failure time and the commutation characteristic data when the result of a commutation failure is a commutation failure. The two-phase commutation determination module is used to determine the two-phase commutation results based on the two-phase commutation failure intervals, the valve-side current waveform, and the preset two-phase commutation failure criteria.

9. An electronic device, characterized in that, The device includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the multi-type high-voltage DC commutation failure detection method as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the multi-type high-voltage DC commutation failure detection method as described in any one of claims 1-7.

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