Fault protection method, device and equipment based on current monitoring, readable storage medium and program product

Abstract

The invention relates to a fault protection method and device based on current monitoring, computer equipment, a computer readable storage medium and a computer program product. The method comprises the following steps: acquiring a position signal of a converter transformer incoming circuit breaker in a direct current power transmission system, and acquiring a network side voltage and a network side zero sequence current of the converter transformer; judging whether the direct-current power transmission system meets a closing fault criterion according to the position signal, judging whether the direct-current power transmission system meets a voltage fault criterion according to the grid-side voltage, and judging whether the direct-current power transmission system meets a current fault criterion according to the grid-side zero-sequence current; and determining a fault type of the DC power transmission system according to a judgment result, and determining a fault protection action for the DC power transmission system according to the fault type by using a fault protection strategy. By adopting the method, the safety and the stability of the direct-current power transmission system can be effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of DC power transmission, and in particular, to a fault protection method, device, computer device, computer-readable storage medium, and computer program product based on current monitoring. Background Art

[0002] DC power transmission technology is an emerging power technology and also the development direction of long-distance power transmission projects. The converter transformer is a key device in the DC power transmission system, and the safe operation of the converter transformer has a great impact on the safety and stability of the DC power transmission system.

[0003] In the prior art, zero-sequence overcurrent protection is configured for the converter transformer to ensure the safe operation of the converter transformer and improve the safety and stability of the DC power transmission system.

[0004] However, due to the poor accuracy of this method, it not only affects the availability of the converter transformer but also results in low safety and stability of the DC power transmission system. Summary of the Invention

[0005] Based on this, it is necessary to provide a fault protection method, device, computer device, computer-readable storage medium, and computer program product based on current monitoring with relatively high accuracy for the above technical problems.

[0006] In a first aspect, the present application provides a fault protection method based on current monitoring, including:

[0007] Obtain the position signal of the incoming line breaker of the converter transformer in the DC power transmission system, and obtain the grid-side voltage and grid-side zero-sequence current of the converter transformer;

[0008] Judge whether the DC power transmission system meets the closing fault criterion according to the position signal, judge whether the DC power transmission system meets the voltage fault criterion according to the grid-side voltage, and judge whether the DC power transmission system meets the current fault criterion according to the grid-side zero-sequence current;

[0009] Determine the fault type of the DC power transmission system according to the judgment result, and use the fault protection strategy to determine the fault protection action for the DC power transmission system according to the fault type.

[0010] In one embodiment, the position signal includes a closing position signal and a tripping position signal. Judging whether the DC power transmission system meets the closing fault criterion according to the position signal includes: after the position signal changes from the tripping position signal to the closing position signal, collect the closing duration of the closing position signal; obtain a first time threshold, and determine that the DC power transmission system meets the closing fault criterion when the closing duration is greater than the first time indicated by the first time threshold.

[0011] In one embodiment, determining whether the HVDC transmission system satisfies a voltage fault criterion based on the grid-side voltage includes: obtaining a voltage threshold and a second time threshold, and determining whether the grid-side voltage is greater than the target voltage indicated by the voltage threshold; when the grid-side voltage is greater than the target voltage, determining the duration of the grid-side voltage being greater than the target voltage, and determining whether the voltage duration is greater than the second time indicated by the second time threshold; when the voltage duration is greater than the second time, determining that the HVDC transmission system satisfies the voltage fault criterion.

[0012] In one embodiment, determining whether the HVDC transmission system satisfies a current fault criterion based on the grid-side zero-sequence current includes: obtaining a first current threshold, a second current threshold, a third current threshold, a third time threshold, a fourth time threshold, and a fifth time threshold, where the first current threshold is less than the second current threshold, the second current threshold is less than the third current threshold, the third time threshold is less than the fourth time threshold, and the fourth time threshold is less than the fifth time threshold; when the grid-side zero-sequence current is greater than the first current indicated by the first current threshold and less than the second current indicated by the second current threshold, determining the duration of the grid-side zero-sequence current being greater than the first current and less than the second current, and when the first current duration is greater than the third time indicated by the third time threshold, determining that the HVDC transmission system satisfies the first current fault criterion in the current fault criterion; when the grid-side zero-sequence current is greater than the second current indicated by the second current threshold and less than the third current indicated by the third current threshold, determining the duration of the grid-side zero-sequence current being greater than the second current and less than the third current, and when the second current duration is greater than the fourth time indicated by the fourth time threshold, determining that the HVDC transmission system satisfies the second current fault criterion in the current fault criterion; when the grid-side zero-sequence current is greater than the third current indicated by the third current threshold, determining the duration of the grid-side zero-sequence current being greater than the third current, and when the third current duration is greater than the fifth time indicated by the fifth time threshold, determining that the HVDC transmission system satisfies the third current fault criterion in the current fault criterion.

[0013] In one embodiment, determining the fault type of the HVDC transmission system according to the judgment result includes: when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the first current fault criterion, determining that the fault type of the HVDC transmission system is the first type; when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the second current fault criterion, determining that the fault type of the HVDC transmission system is the second type; when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the third current fault criterion, determining that the fault type of the HVDC transmission system is the third type.

[0014] In one embodiment, using the fault protection strategy to determine the fault protection action for the HVDC transmission system according to the fault type includes: when the fault type is the first type, using the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, and determining the first fault protection action corresponding to the first type according to the first type, where the first fault protection action is to output an alarm message for indicating the overlimit of zero-sequence current; when the fault type is the second type, using the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, and determining the second fault protection action corresponding to the second type according to the second type, where the second fault protection action is to prohibit the tap changer of the converter transformer from adjusting the tap position; when the fault type is the third type, using the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, and determining the third fault protection action corresponding to the third type according to the third type, where the third fault protection action is to disconnect the incoming line breaker of the converter transformer and block the HVDC transmission system.

[0015] In a second aspect, the present application also provides a fault protection device based on current monitoring, including:

[0016] An acquisition module, configured to acquire the position signal of the incoming line breaker of the converter transformer in the HVDC transmission system, and acquire the grid-side voltage and grid-side zero-sequence current of the converter transformer;

[0017] A judgment module, configured to judge whether the HVDC transmission system meets the closing fault criterion according to the position signal, judge whether the HVDC transmission system meets the voltage fault criterion according to the grid-side voltage, and judge whether the HVDC transmission system meets the current fault criterion according to the grid-side zero-sequence current;

[0018] An execution module, configured to determine the fault type of the HVDC transmission system according to the judgment result, and use the fault protection strategy to determine the fault protection action for the HVDC transmission system according to the fault type.

[0019] In one embodiment, the position signal includes a closing position signal and a tripping position signal. The determining module is specifically configured to, after the position signal changes from the tripping position signal to the closing position signal, collect the closing duration of the closing position signal; obtain a first time threshold, and determine that the DC power transmission system meets the closing fault criterion when the closing duration is greater than the first time indicated by the first time threshold.

[0020] In one embodiment, the determining module is specifically configured to obtain a voltage threshold and a second time threshold, and determine whether the grid-side voltage is greater than the target voltage indicated by the voltage threshold; when the grid-side voltage is greater than the target voltage, determine the voltage duration during which the grid-side voltage is greater than the target voltage, and determine whether the voltage duration is greater than the second time indicated by the second time threshold; when the voltage duration is greater than the second time, determine that the DC power transmission system meets the voltage fault criterion.

[0021] In one embodiment, the determining module is specifically configured to obtain a first current threshold, a second current threshold, a third current threshold, a third time threshold, a fourth time threshold, and a fifth time threshold, where the first current threshold is less than the second current threshold, the second current threshold is less than the third current threshold, the third time threshold is less than the fourth time threshold, and the fourth time threshold is less than the fifth time threshold; when the grid-side zero-sequence current is greater than the first current indicated by the first current threshold and less than the second current indicated by the second current threshold, determine the first current duration during which the grid-side zero-sequence current is greater than the first current and less than the second current, and when the first current duration is greater than the third time indicated by the third time threshold, determine that the DC power transmission system meets the first current fault criterion in the current fault criterion; when the grid-side zero-sequence current is greater than the second current indicated by the second current threshold and less than the third current indicated by the third current threshold, determine the second current duration during which the grid-side zero-sequence current is greater than the second current and less than the third current, and when the second current duration is greater than the fourth time indicated by the fourth time threshold, determine that the DC power transmission system meets the second current fault criterion in the current fault criterion; when the grid-side zero-sequence current is greater than the third current indicated by the third current threshold, determine the third current duration during which the grid-side zero-sequence current is greater than the third current, and when the third current duration is greater than the fifth time indicated by the fifth time threshold, determine that the DC power transmission system meets the third current fault criterion in the current fault criterion.

[0022] In one embodiment, the execution module is specifically configured to determine that the fault type of the DC power transmission system is the first type when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the first current fault criterion; determine that the fault type of the DC power transmission system is the second type when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the second current fault criterion; and determine that the fault type of the DC power transmission system is the third type when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the third current fault criterion.

[0023] In one embodiment, the execution module is specifically configured to, when the fault type is the first type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the first fault protection action corresponding to the first type according to the first type, where the first fault protection action is to output an alarm message for prompting over-limit zero-sequence current; when the fault type is the second type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the second fault protection action corresponding to the second type according to the second type, where the second fault protection action is to prohibit the tap changer of the converter transformer from adjusting the tap position; when the fault type is the third type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the third fault protection action corresponding to the third type according to the third type, where the third fault protection action is to disconnect the incoming line breaker of the converter transformer and block the DC power transmission system.

[0024] In a third aspect, the present application further provides a computer device, including a memory and a processor, where the memory stores a computer program, and when the processor executes the computer program, the steps of the method in any one of the embodiments in the first aspect are implemented.

[0025] In a fourth aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method in any one of the embodiments in the first aspect are implemented.

[0026] In a fifth aspect, the present application further provides a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the method in any one of the embodiments in the first aspect are implemented.

[0027] The above-mentioned fault protection method, device, computer device, computer-readable storage medium, and computer program product based on current monitoring first obtain the position signal of the incoming line breaker of the converter transformer in the DC power transmission system, and obtain the grid-side voltage and grid-side zero-sequence current of the converter transformer. Then, it is determined whether the DC power transmission system meets the closing fault criterion according to the position signal, whether the DC power transmission system meets the voltage fault criterion according to the grid-side voltage, and whether the DC power transmission system meets the current fault criterion according to the grid-side zero-sequence current. Then, according to the judgment result, the fault type of the DC power transmission system is determined, and a fault protection strategy is used to determine the fault protection action for the DC power transmission system according to the fault type. Compared with the prior art method of only observing the zero-sequence current to judge whether there is a fault and then performing a protection action, the fault protection method provided by this application also relies on the position signal of the incoming line breaker of the converter transformer and the grid-side voltage of the converter transformer, improving the accuracy of fault judgment, and thus effectively improving the availability of the converter transformer. Moreover, different fault protection actions can be performed according to different fault types, effectively improving the safety and stability of the DC power transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments of the present application or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic flowchart of a fault protection method based on current monitoring in an embodiment;

[0030] Figure 2 It is a schematic flowchart of a method for determining whether a DC power transmission system meets the closing fault criterion according to a position signal in an embodiment;

[0031] Figure 3 It is a schematic flowchart of a method for determining whether a DC power transmission system meets the voltage fault criterion according to the grid-side voltage in an embodiment;

[0032] Figure 4 It is a schematic flowchart of a method for determining whether a DC power transmission system meets the current fault criterion according to the grid-side zero-sequence current in an embodiment;

[0033] Figure 5 It is a schematic flowchart of a method for determining the fault type of a DC power transmission system according to a judgment result in an embodiment;

[0034] Figure 6Schematic flowchart of a method for determining fault protection actions for a HVDC transmission system according to a fault type by using a fault protection strategy in an embodiment;

[0035] Figure 7 Schematic flowchart of a fault protection method based on current monitoring in another embodiment;

[0036] Figure 8 Block diagram of a fault protection device based on current monitoring in an embodiment;

[0037] Figure 9 Internal structure diagram of a computer device in an embodiment;

[0038] Figure 10 Internal structure diagram of a computer device in another embodiment. Detailed implementation manners

[0039] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0040] HVDC transmission technology is an emerging power technology and also the development direction of long-distance power transmission projects. The converter transformer is a key device in the HVDC transmission system, and the safe operation of the converter transformer has a great impact on the safety and stability of the HVDC transmission system.

[0041] In the prior art, zero-sequence overcurrent protection is configured for the converter transformer to ensure the safe operation of the converter transformer and improve the safety and stability of the HVDC transmission system.

[0042] However, this protection cannot cover all working conditions and there are still risks of protection refusal or misoperation. Specifically, for example, when the incoming line breaker of the converter transformer is charged, a large inrush current will be generated, and there is a risk of misoperation for the zero-sequence overcurrent protection. For example, this protection is mainly for the case where the zero-sequence current is large after a ground fault occurs in the converter transformer, and it cannot protect against fault conditions with small currents. Due to the poor accuracy of this method, it not only affects the availability of the converter transformer, but also results in low safety and stability of the HVDC transmission system.

[0043] In view of this, the present application provides a fault protection method based on current monitoring, which can improve the accuracy of fault judgment, thereby improving the availability of the converter transformer and ensuring the safety and stability of the HVDC transmission system.

[0044] The fault protection method based on current monitoring provided by the present application may be executed by a computer device, and the computer device may be a terminal or a server.

[0045] In an exemplary embodiment, as Figure 1 shown, a fault protection method based on current monitoring is provided, and the method includes the following steps:

[0046] Step 101, obtain the position signal of the incoming line breaker of the converter transformer in the HVDC transmission system, and obtain the grid-side voltage and grid-side zero-sequence current of the converter transformer.

[0047] The HVDC transmission system refers to a power system that can transmit electric energy using direct current. Exemplarily, the HVDC transmission system can be composed of three major parts: a rectifier station, an HVDC transmission line, and an inverter station.

[0048] The converter transformer refers to the core device connecting the AC system and the converter bridge in the HVDC transmission system, and is used to realize the mutual conversion between AC and DC.

[0049] The incoming line breaker can be used to connect or disconnect the circuit between the AC system and the converter transformer during normal operation, and realize the power supply control of the converter transformer. In case of a fault, it can quickly cut off the fault current, protect the converter transformer and the AC system from the influence of the fault, and prevent the expansion of the fault.

[0050] The position signal can be used to characterize the working state of the incoming line breaker.

[0051] The grid-side voltage refers to the voltage on the side where the converter transformer is connected to the AC system. The grid-side zero-sequence current refers to a special current that appears on the side where the converter transformer is connected to the AC system (i.e., the grid side) when the HVDC transmission system has a three-phase asymmetric operation condition (such as a single-phase ground fault, a serious imbalance of three-phase loads, etc.).

[0052] In some exemplary embodiments, the position signal of the incoming line breaker of the converter transformer in the HVDC transmission system can be obtained through an auxiliary switch.

[0053] Specifically, the incoming line breaker of the converter transformer is usually equipped with an auxiliary switch, which is connected to the main contact of the breaker through a mechanical linkage device. When the breaker performs a closing or opening operation, the movement of the main contact will drive the contacts of the auxiliary switch to move synchronously. The auxiliary switch generally has multiple contacts, and these contacts will show different on-off states according to the closing and opening states of the breaker. For example, when the breaker is in the closed position, the corresponding normally open contact of the auxiliary switch closes and the normally closed contact opens; when the breaker is open, the normally open contact opens and the normally closed contact closes. The state changes of these contacts represent the position information of the breaker.

[0054] Further, after obtaining the position signal of the incoming breaker of the converter transformer in the HVDC system, the computer device can also obtain the grid-side voltage through a voltage transformer and obtain the grid-side zero-sequence current through a zero-sequence current transformer.

[0055] Step 102: Determine whether the HVDC system meets the closing fault criterion according to the position signal, determine whether the HVDC system meets the voltage fault criterion according to the grid-side voltage, and determine whether the HVDC system meets the current fault criterion according to the grid-side zero-sequence current.

[0056] In some exemplary embodiments, after obtaining the position signal, the grid-side voltage, and the grid-side zero-sequence current, the computer device can determine whether the HVDC system meets the closing fault criterion according to the position signal, determine whether the HVDC system meets the voltage fault criterion according to the grid-side voltage, and determine whether the HVDC system meets the current fault criterion according to the grid-side zero-sequence current.

[0057] Specifically, the computer device can determine whether the HVDC system meets the closing fault criterion based on the position signal and a pre-trained closing fault criterion determination model. The computer device can also determine whether the HVDC system meets the voltage fault criterion based on the grid-side voltage and a pre-trained voltage fault criterion determination model. The computer device can also determine whether the HVDC system meets the current fault criterion based on the grid-side zero-sequence current and a pre-trained current fault criterion determination model.

[0058] Step 103: Determine the fault type of the HVDC system according to the judgment result, and use the fault protection strategy to determine the fault protection action for the HVDC system according to the fault type.

[0059] In some exemplary embodiments, after determining the judgment result, the computer device can input the judgment result into a pre-trained fault type determination model to obtain the fault type of the HVDC system output by the fault type determination model.

[0060] Further, after determining the fault type, the computer device can input the fault type and the fault protection strategy into a pre-trained fault protection action determination model to obtain the fault protection action for the HVDC system output by the fault protection action determination model.

[0061] The above-mentioned fault protection method based on current monitoring first obtains the position signal of the incoming line breaker of the converter transformer in the DC transmission system, and obtains the grid-side voltage and grid-side zero-sequence current of the converter transformer. Then, it judges whether the DC transmission system meets the closing fault criterion according to the position signal, judges whether the DC transmission system meets the voltage fault criterion according to the grid-side voltage, and judges whether the DC transmission system meets the current fault criterion according to the grid-side zero-sequence current. Then, according to the judgment result, it determines the fault type of the DC transmission system, and uses the fault protection strategy to determine the fault protection action for the DC transmission system according to the fault type. Compared with the prior art method of only observing the zero-sequence current to judge whether there is a fault and then performing the protection action, the fault protection method provided by this application also relies on the position signal of the incoming line breaker of the converter transformer and the grid-side voltage of the converter transformer, improving the accuracy of fault judgment, and thus effectively improving the availability of the converter transformer. Moreover, different fault protection actions can be executed according to different fault types, effectively improving the safety and stability of the DC transmission system.

[0062] In an exemplary embodiment, as Figure 2 shown, the position signal includes a closing position signal and a tripping position signal. Judging whether the DC transmission system meets the closing fault criterion according to the position signal includes the following steps:

[0063] Step 201: After the position signal changes from the tripping position signal to the closing position signal, collect the closing duration of the closing position signal.

[0064] The tripping position signal indicates that the incoming line breaker of the converter transformer is in the open state. At this time, the main contacts of the incoming line breaker are separated, cutting off the circuit connection between the AC system and the converter transformer, and current cannot flow through the incoming line breaker.

[0065] The closing position signal indicates that the incoming line breaker of the converter transformer is in the closed state, the main contacts are connected, the circuit between the AC system and the converter transformer is conducting, and current can be transmitted normally.

[0066] The closing signal duration refers to the time elapsed since the position signal of the incoming line breaker of the converter transformer changed from the tripping position signal to the closing position signal until the current moment, during which the breaker has always remained in the closing position signal.

[0067] In some exemplary embodiments, after the computer device obtains the position signal, if it determines that the position signal has changed from the tripping signal to the closing signal, it collects the closing duration of the closing position signal.

[0068] Specifically, if the computer device determines that the position signal is a trip signal after obtaining the position signal at the first moment, and determines that the position signal is a closing signal after obtaining the position signal at the second moment, then start timing from the second moment to collect the closing duration of the closing position signal.

[0069] Step 202: Obtain a first time threshold. When the closing duration is greater than the first time indicated by the first time threshold, determine that the DC power transmission system meets the closing fault criterion.

[0070] Optionally, the first time threshold can be pre-set by a technician according to actual needs. Specifically, the first time indicated by the first time threshold can be 2 minutes.

[0071] In some exemplary embodiments, after the position signal changes from the trip position signal to the closing position signal, the computer can collect the closing duration of the closing position signal.

[0072] Further, the computer device can also obtain the first time threshold, and when the closing duration is greater than the first time indicated by the first time threshold, determine that the DC power transmission system meets the closing fault criterion.

[0073] If the closing duration is less than or equal to the first time indicated by the first time threshold, determine that the DC power transmission system does not meet the closing fault criterion.

[0074] In an exemplary embodiment as Figure 3 shown, determining whether the DC power transmission system meets the voltage fault criterion according to the grid-side voltage includes the following steps:

[0075] Step 301: Obtain a voltage threshold and a second time threshold, and determine whether the grid-side voltage is greater than the target voltage indicated by the voltage threshold.

[0076] Optionally, the voltage threshold can be pre-set by a technician according to actual needs. Specifically, the target voltage indicated by the voltage threshold can be 0.6 p.u. Among them, 1.0 p.u. corresponds to the rated voltage value when the converter transformer operates normally.

[0077] The second time threshold can be pre-set by a technician according to actual needs. Specifically, the second time indicated by the second time threshold can be 50 milliseconds.

[0078] In some exemplary embodiments, the computer device can first obtain the voltage threshold and the second time threshold, and determine whether the grid-side voltage is greater than the target voltage indicated by the voltage threshold.

[0079] Further, if the computer device determines that the grid-side voltage is less than or equal to the target voltage, it determines that the HVDC system does not meet the voltage fault criterion.

[0080] Step 302: When the grid-side voltage is greater than the target voltage, determine the duration of the grid-side voltage being greater than the target voltage, and determine whether the duration is greater than the second time indicated by the second time threshold.

[0081] In some exemplary embodiments, when the grid-side voltage is greater than the target voltage, the computer device can determine the duration of the grid-side voltage being greater than the target voltage, and determine whether the duration is greater than the second time indicated by the second time threshold.

[0082] Further, if the computer device determines that the duration is less than or equal to the second time indicated by the second time threshold, it determines that the HVDC system does not meet the voltage fault criterion.

[0083] Step 303: When the duration is greater than the second time, determine that the HVDC system meets the voltage fault criterion.

[0084] In some exemplary embodiments, when the duration is greater than the second time, the computer device determines that the HVDC system meets the voltage fault criterion.

[0085] In an exemplary embodiment, as Figure 4 shown, determining whether the HVDC system meets the current fault criterion based on the grid-side zero-sequence current includes the following steps:

[0086] Step 401: Obtain a first current threshold, a second current threshold, a third current threshold, a third time threshold, a fourth time threshold, and a fifth time threshold.

[0087] Among them, the first current threshold is less than the second current threshold, the second current threshold is less than the third current threshold, the third time threshold is less than the fourth time threshold, and the fourth time threshold is less than the fifth time threshold.

[0088] Optionally, the first current threshold, the second current threshold, the third current threshold, the third time threshold, the fourth time threshold, and the fifth time threshold can be preset by those skilled in the art according to actual needs.

[0089] Step 402: When the zero-sequence current on the network side is greater than the first current indicated by the first current threshold and less than the second current indicated by the second current threshold, determine the first current duration during which the zero-sequence current on the network side is greater than the first current and less than the second current. And when the first current duration is greater than the third time indicated by the third time threshold, determine that the DC power transmission system meets the first current fault criterion in the current fault criterion.

[0090] Optionally, the first current indicated by the first current threshold may be 60A, and the second current indicated by the second current threshold may be 120A. The third time indicated by the third time threshold may be 100 milliseconds.

[0091] In some exemplary embodiments, when the zero-sequence current on the network side is greater than the first current indicated by the first current threshold and less than the second current indicated by the second current threshold, the computer device may determine the first current duration during which the zero-sequence current on the network side is greater than the first current and less than the second current.

[0092] Further, when the first current duration is greater than the third time indicated by the third time threshold, the computer device determines that the DC power transmission system meets the first current fault criterion in the current fault criterion.

[0093] Step 403: When the zero-sequence current on the network side is greater than the second current indicated by the second current threshold and less than the third current indicated by the third current threshold, determine the second current duration during which the zero-sequence current on the network side is greater than the second current and less than the third current. And when the second current duration is greater than the fourth time indicated by the fourth time threshold, determine that the DC power transmission system meets the second current fault criterion in the current fault criterion.

[0094] Optionally, the third current indicated by the third current threshold may be 200A. The fourth time indicated by the fourth time threshold may be 1000 milliseconds.

[0095] In some exemplary embodiments, when the zero-sequence current on the network side is greater than the second current indicated by the second current threshold and less than the third current indicated by the third current threshold, the computer device may determine the second current duration during which the zero-sequence current on the network side is greater than the second current and less than the third current.

[0096] Further, when the second current duration is greater than the fourth time indicated by the fourth time threshold, the computer device may determine that the DC power transmission system meets the second current fault criterion in the current fault criterion.

[0097] Step 404: When the grid-side zero-sequence current is greater than the third current indicated by the third current threshold, determine the third current duration during which the grid-side zero-sequence current is greater than the third current. When the third current duration is greater than the fifth time indicated by the fifth time threshold, determine that the DC power transmission system satisfies the third current fault criterion in the current fault criterion.

[0098] Optionally, the fifth time indicated by the fifth time threshold may be 5000 milliseconds.

[0099] In some exemplary embodiments, when the grid-side zero-sequence current is greater than the third current indicated by the third current threshold, the computer device may determine the third current duration during which the grid-side zero-sequence current is greater than the third current.

[0100] Further, when the third current duration is greater than the fifth time indicated by the fifth time threshold, the computer device may determine that the DC power transmission system satisfies the third current fault criterion in the current fault criterion.

[0101] In an exemplary embodiment, as Figure 5 shown, determining the fault type of the DC power transmission system according to the judgment result includes the following steps:

[0102] Step 501: When the judgment result indicates that the target DC system satisfies the closing fault criterion, the voltage fault criterion, and the first current fault criterion, determine that the fault type of the DC power transmission system is the first type.

[0103] In some exemplary embodiments, when the judgment result indicates that the target DC system satisfies the closing fault criterion, the voltage fault criterion, and the first current fault criterion, the computer device determines that the fault type of the DC power transmission system is the first type.

[0104] Step 502: When the judgment result indicates that the target DC system satisfies the closing fault criterion, the voltage fault criterion, and the second current fault criterion, determine that the fault type of the DC power transmission system is the second type.

[0105] In some exemplary embodiments, when the judgment result indicates that the target DC system satisfies the closing fault criterion, the voltage fault criterion, and the second current fault criterion, the computer device determines that the fault type of the DC power transmission system is the second type.

[0106] Step 503: When the judgment result indicates that the target DC system satisfies the closing fault criterion, the voltage fault criterion, and the third current fault criterion, determine that the fault type of the DC power transmission system is the third type.

[0107] In some exemplary embodiments, when the judgment result indicates that the target DC system satisfies the closing fault criterion, the voltage fault criterion, and the third current fault criterion, the computer device determines that the fault type of the DC power transmission system is the third type.

[0108] In an exemplary embodiment, as Figure 6 shown, using the fault protection strategy, determining the fault protection action for the DC power transmission system according to the fault type includes the following steps:

[0109] Step 601: When the fault type is the first type, using the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, determine the first fault protection action corresponding to the first type according to the first type.

[0110] Wherein, the first fault protection action is to output an alarm message for prompting over-limit zero-sequence current.

[0111] Exemplarily, the fault protection strategy can be as shown in Table 1, which stores the mapping relationship between the fault type and the fault protection action.

[0112] Table 1

[0113]

[0114] In some exemplary embodiments, when the fault type is the first type, the computer device can use the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy to determine the first fault protection action corresponding to the first type according to the first type.

[0115] Step 602: When the fault type is the second type, using the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, determine the second fault protection action corresponding to the second type according to the second type.

[0116] Wherein, the second fault protection action is to prohibit the tap changer of the converter transformer from adjusting the tap position.

[0117] In some exemplary embodiments, when the fault type is the second type, the computer device can use the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy to determine the second fault protection action corresponding to the second type according to the second type.

[0118] Step 603: When the fault type is the third type, using the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, determine the third fault protection action corresponding to the third type according to the third type.

[0119] Among them, the third fault protection action is to disconnect the incoming line breaker of the converter transformer and block the DC power transmission system.

[0120] In some exemplary embodiments, when the fault type of the computer device is the third type, by using the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, the third fault protection action corresponding to the third type can be determined according to the third type.

[0121] In an exemplary embodiment, as Figure 7 shown, another fault protection method based on current monitoring is provided, and this method includes the following steps:

[0122] Step 701: Obtain the position signal of the incoming line breaker of the converter transformer in the DC power transmission system, and obtain the grid-side voltage and grid-side zero-sequence current of the converter transformer; the position signal includes a closing position signal and a tripping position signal.

[0123] Step 702: After the position signal changes from the tripping position signal to the closing position signal, collect the closing duration of the closing position signal; obtain a first time threshold, and when the closing duration is greater than the first time indicated by the first time threshold, determine that the DC power transmission system meets the closing fault criterion; obtain a voltage threshold and a second time threshold, and determine whether the grid-side voltage is greater than the target voltage indicated by the voltage threshold; when the grid-side voltage is greater than the target voltage, determine the voltage duration during which the grid-side voltage is greater than the target voltage, and determine whether the voltage duration is greater than the second time indicated by the second time threshold; when the voltage duration is greater than the second time, determine that the DC power transmission system meets the voltage fault criterion.

[0124] Step 703: Obtain a first current threshold, a second current threshold, a third current threshold, a third time threshold, a fourth time threshold, and a fifth time threshold, where the first current threshold is less than the second current threshold, the second current threshold is less than the third current threshold, the third time threshold is less than the fourth time threshold, and the fourth time threshold is less than the fifth time threshold; when the grid-side zero-sequence current is greater than the first current indicated by the first current threshold and less than the second current indicated by the second current threshold, determine the first current duration during which the grid-side zero-sequence current is greater than the first current and less than the second current, and when the first current duration is greater than the third time indicated by the third time threshold, determine that the DC power transmission system meets the first current fault criterion in the current fault criterion.

[0125] Step 704: When the grid-side zero-sequence current is greater than the second current indicated by the second current threshold and less than the third current indicated by the third current threshold, determine the duration of the second current during which the grid-side zero-sequence current is greater than the second current and less than the third current. When the duration of the second current is greater than the fourth time indicated by the fourth time threshold, determine that the DC power transmission system meets the second current fault criterion in the current fault criterion; when the grid-side zero-sequence current is greater than the third current indicated by the third current threshold, determine the duration of the third current during which the grid-side zero-sequence current is greater than the third current. When the duration of the third current is greater than the fifth time indicated by the fifth time threshold, determine that the DC power transmission system meets the third current fault criterion in the current fault criterion.

[0126] Step 705: When the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the first current fault criterion, determine that the fault type of the DC power transmission system is the first type; when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the second current fault criterion, determine that the fault type of the DC power transmission system is the second type; when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the third current fault criterion, determine that the fault type of the DC power transmission system is the third type;

[0127] Step 706: When the fault type is the first type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the first fault protection action corresponding to the first type according to the first type. The first fault protection action is to output an alarm message for indicating the overlimit of the zero-sequence current; when the fault type is the second type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the second fault protection action corresponding to the second type according to the second type. The second fault protection action is to prohibit the tap changer of the converter transformer from adjusting the tap position; when the fault type is the third type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the third fault protection action corresponding to the third type according to the third type. The third fault protection action is to disconnect the incoming line breaker of the converter transformer and block the DC power transmission system.

[0128] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are displayed in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, there is no strict order limit for the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0129] Based on the same inventive concept, an embodiment of the present application also provides a fault protection device based on current monitoring for implementing the above-mentioned fault protection method based on current monitoring. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the following fault protection devices based on current monitoring can refer to the limitations on the fault protection method based on current monitoring in the above text, and will not be elaborated here.

[0130] In an exemplary embodiment, as Figure 8 shown, a fault protection device 800 based on current monitoring is provided, including: an acquisition module, a judgment module 801, and an execution module 802, where:

[0131] The acquisition module 801 is configured to acquire the position signal of the incoming line breaker of the converter transformer in the DC transmission system, and acquire the grid-side voltage and grid-side zero-sequence current of the converter transformer;

[0132] The judgment module 802 is configured to judge whether the DC transmission system meets the closing fault criterion according to the position signal, judge whether the DC transmission system meets the voltage fault criterion according to the grid-side voltage, and judge whether the DC transmission system meets the current fault criterion according to the grid-side zero-sequence current;

[0133] The execution module 803 is configured to determine the fault type of the DC transmission system according to the judgment result, and use the fault protection strategy to determine the fault protection action for the DC transmission system according to the fault type.

[0134] In one embodiment, the position signal includes a closing position signal and a tripping position signal. The judgment module 802 is specifically configured to collect the closing duration of the closing position signal after the position signal changes from the tripping position signal to the closing position signal; obtain a first time threshold, and determine that the DC power transmission system satisfies the closing fault criterion when the closing duration is greater than the first time indicated by the first time threshold.

[0135] In one embodiment, the judgment module 802 is specifically configured to obtain a voltage threshold and a second time threshold, and determine whether the grid-side voltage is greater than the target voltage indicated by the voltage threshold; when the grid-side voltage is greater than the target voltage, determine the voltage duration during which the grid-side voltage is greater than the target voltage, and determine whether the voltage duration is greater than the second time indicated by the second time threshold; when the voltage duration is greater than the second time, determine that the DC power transmission system satisfies the voltage fault criterion.

[0136] In one embodiment, the judgment module 802 is specifically configured to obtain a first current threshold, a second current threshold, a third current threshold, a third time threshold, a fourth time threshold, and a fifth time threshold, where the first current threshold is less than the second current threshold, the second current threshold is less than the third current threshold, the third time threshold is less than the fourth time threshold, and the fourth time threshold is less than the fifth time threshold; when the grid-side zero-sequence current is greater than the first current indicated by the first current threshold and less than the second current indicated by the second current threshold, determine the first current duration during which the grid-side zero-sequence current is greater than the first current and less than the second current, and when the first current duration is greater than the third time indicated by the third time threshold, determine that the DC power transmission system satisfies the first current fault criterion in the current fault criterion; when the grid-side zero-sequence current is greater than the second current indicated by the second current threshold and less than the third current indicated by the third current threshold, determine the second current duration during which the grid-side zero-sequence current is greater than the second current and less than the third current, and when the second current duration is greater than the fourth time indicated by the fourth time threshold, determine that the DC power transmission system satisfies the second current fault criterion in the current fault criterion; when the grid-side zero-sequence current is greater than the third current indicated by the third current threshold, determine the third current duration during which the grid-side zero-sequence current is greater than the third current, and when the third current duration is greater than the fifth time indicated by the fifth time threshold, determine that the DC power transmission system satisfies the third current fault criterion in the current fault criterion.

[0137] In one embodiment, the execution module 803 is specifically configured to determine that the fault type of the DC power transmission system is the first type when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the first current fault criterion; determine that the fault type of the DC power transmission system is the second type when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the second current fault criterion; and determine that the fault type of the DC power transmission system is the third type when the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the third current fault criterion.

[0138] In one embodiment, the execution module 803 is specifically configured to, when the fault type is the first type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the first fault protection action corresponding to the first type according to the first type, where the first fault protection action is to output an alarm message for prompting over-limit zero-sequence current; when the fault type is the second type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the second fault protection action corresponding to the second type according to the second type, where the second fault protection action is to prohibit the tap changer of the converter transformer from adjusting the tap position; when the fault type is the third type, use the mapping relationship between the fault type indicated by the fault protection strategy and the fault protection action, and determine the third fault protection action corresponding to the third type according to the third type, where the third fault protection action is to disconnect the incoming line breaker of the converter transformer and block the DC power transmission system.

[0139] Each module in the above fault protection device based on current monitoring can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form to facilitate the processor to call and execute the operations corresponding to the above respective modules.

[0140] In an exemplary embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as Figure 9As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals through a network. When the computer program is executed by the processor, it implements a fault protection method based on current monitoring.

[0141] In an exemplary embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as Figure 10 shown. The computer device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface, the display unit, and the input device are connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner. The wireless manner can be implemented through WIFI, a mobile cellular network, near field communication (Near Field Communication, NFC), or other technologies. When the computer program is executed by the processor, it implements a fault protection method based on current monitoring.

[0142] Those skilled in the art can understand that Figure 9 and Figure 10 the structures shown in

[0143] In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the steps described in any of the above embodiments are implemented.

[0144] In an embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps described in any of the above embodiments are implemented.

[0145] In an embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the steps described in any of the above embodiments are implemented.

[0146] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in this application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in this application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, artificial intelligence (AI) processors, etc., without limitation.

[0147] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this application.

[0148] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A fault protection method based on current monitoring, characterized in that, The method includes: Obtaining the position signal of the incoming breaker of the converter transformer in the HVDC transmission system, and obtaining the grid-side voltage and grid-side zero-sequence current of the converter transformer; Judging whether the HVDC transmission system meets the closing fault criterion according to the position signal, judging whether the HVDC transmission system meets the voltage fault criterion according to the grid-side voltage, and judging whether the HVDC transmission system meets the current fault criterion according to the grid-side zero-sequence current; Determining the fault type of the HVDC transmission system according to the judgment result, and using the fault protection strategy to determine the fault protection action for the HVDC transmission system according to the fault type.

2. The method according to claim 1, characterized in that, The position signal includes a closing position signal and a tripping position signal. Judging whether the HVDC transmission system meets the closing fault criterion according to the position signal includes: After the position signal changes from the tripping position signal to the closing position signal, collecting the closing duration of the closing position signal; Obtaining a first time threshold, and determining that the HVDC transmission system meets the closing fault criterion when the closing duration is greater than the first time indicated by the first time threshold.

3. The method according to claim 2, wherein Judging whether the HVDC transmission system meets the voltage fault criterion according to the grid-side voltage includes: Obtaining a voltage threshold and a second time threshold, and determining whether the grid-side voltage is greater than the target voltage indicated by the voltage threshold; When the grid-side voltage is greater than the target voltage, determining the voltage duration when the grid-side voltage is greater than the target voltage, and determining whether the voltage duration is greater than the second time indicated by the second time threshold; When the voltage duration is greater than the second time, determining that the HVDC transmission system meets the voltage fault criterion.

4. The method according to claim 3, wherein Judging whether the HVDC transmission system meets the current fault criterion according to the grid-side zero-sequence current includes: Obtaining a first current threshold, a second current threshold, a third current threshold, a third time threshold, a fourth time threshold, and a fifth time threshold, where the first current threshold is less than the second current threshold, the second current threshold is less than the third current threshold, the third time threshold is less than the fourth time threshold, and the fourth time threshold is less than the fifth time threshold; When the grid-side zero-sequence current is greater than the first current indicated by the first current threshold and less than the second current indicated by the second current threshold, determining the first current duration when the grid-side zero-sequence current is greater than the first current and less than the second current, and when the first current duration is greater than the third time indicated by the third time threshold, determining that the HVDC transmission system meets the first current fault criterion in the current fault criterion; When the zero-sequence current on the grid side is greater than the second current indicated by the second current threshold and less than the third current indicated by the third current threshold, determine the duration of the second current during which the zero-sequence current on the grid side is greater than the second current and less than the third current. And when the duration of the second current is greater than the fourth time indicated by the fourth time threshold, determine that the DC power transmission system meets the second current fault criterion in the current fault criterion; When the zero-sequence current on the grid side is greater than the third current indicated by the third current threshold, determine the duration of the third current during which the zero-sequence current on the grid side is greater than the third current. And when the duration of the third current is greater than the fifth time indicated by the fifth time threshold, determine that the DC power transmission system meets the third current fault criterion in the current fault criterion.

5. The method according to claim 4, characterized in that, The determining the fault type of the DC power transmission system according to the judgment result includes: When the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the first current fault criterion, determine that the fault type of the DC power transmission system is the first type; When the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the second current fault criterion, determine that the fault type of the DC power transmission system is the second type; When the judgment result indicates that the target DC system meets the closing fault criterion, the voltage fault criterion, and the third current fault criterion, determine that the fault type of the DC power transmission system is the third type.

6. The method according to claim 5, wherein The using the fault protection strategy to determine the fault protection action for the DC power transmission system according to the fault type includes: When the fault type is the first type, use the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, and determine the first fault protection action corresponding to the first type according to the first type. The first fault protection action is to output an alarm message for indicating that the zero-sequence current exceeds the limit; When the fault type is the second type, use the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, and determine the second fault protection action corresponding to the second type according to the second type. The second fault protection action is to prohibit the tap changer of the converter transformer from making tap adjustments; When the fault type is the third type, use the mapping relationship between the fault type and the fault protection action indicated by the fault protection strategy, and determine the third fault protection action corresponding to the third type according to the third type. The third fault protection action is to disconnect the incoming line breaker of the converter transformer and block the DC power transmission system.

7. A fault protection device based on current monitoring, characterized in that, The device includes: An acquisition module, configured to acquire the position signal of the incoming line breaker of the converter transformer in the DC power transmission system, and acquire the grid side voltage and the zero-sequence current on the grid side of the converter transformer; A judgment module, configured to judge whether the HVDC system meets the closing fault criterion according to the position signal, judge whether the HVDC system meets the voltage fault criterion according to the grid-side voltage, and judge whether the HVDC system meets the current fault criterion according to the grid-side zero-sequence current; An execution module, configured to determine the fault type of the HVDC system according to the judgment result, and use a fault protection strategy to determine a fault protection action for the HVDC system according to the fault type.

8. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

Images