Fault power loss cooperative calculation method and system of DC power transmission system of parallel converter topology, and electronic equipment

Abstract

The invention discloses a fault power loss cooperative calculation method and system for a DC power transmission system of a parallel converter topology, and electronic equipment. The method comprises the following steps: establishing communication between a stability control device and DC control and protection equipment of the DC power transmission system; the stability control device judges that the fault-caused locking of the current converter comprises fault-caused locking of the current converter on the side, fault-caused locking of the current converter on the opposite side and locking faults of double sets of crashed fault-pole current converters on the basis of a signal sent by the direct-current control and protection system; according to the direct current pole control mode, whether the sound current converter has the power conversion capability or not when the intra-pole single current converter breaks down is judged, and the direct current fault power loss amount is calculated based on the maximum transmittable power of the remaining sound current converter after the fault. According to the method, the problem of inaccurate fault power loss calculation under complex working conditions of opposite-side single converter locking, bipolar control crash and the like is solved, the effect of accurately calculating the fault power loss amount is achieved, and the method is of great significance to fault analysis, reliability evaluation and safe and stable control of the parallel converter topology direct-current power transmission system.

Description

Technical Field

[0001] The present invention relates to a method, system and electronic equipment for collaborative calculation of fault power loss in a DC power transmission system with a parallel converter topology, and belongs to the technical field of reliability assessment of DC power transmission systems. Background Art

[0002] To reduce voltage stress on primary equipment, all UHVDC transmission systems utilize a series connection of high-voltage and low-voltage converters. When a converter on one side of a pole is shut down due to a fault or maintenance, that pole must switch from full-voltage operation to half-voltage operation, and the corresponding converter on the other side must be shut down simultaneously.

[0003] After the DC expansion, each station and each pole will operate in parallel with two converters. There is a situation where both converters in the pole on the opposite side are in operation after the single converter at the converter station on the opposite side is locked. At the same time, because the converters in the DC pole are operated in parallel, when the single converter in the pole fails when the pole is in the single-pole current control mode, the other healthy converter can still transfer power. There are significant differences in characteristics compared with the existing DC transmission projects, and it is necessary to redesign the calculation method of the DC transmission power loss capacity after the converter lockout fault. Summary of the Invention

[0004] To address the problems of the prior art, the present invention provides a method, system, and electronic device for collaboratively calculating fault power loss in a DC transmission system with a parallel converter topology, which can accurately calculate the amount of transmission power loss in a DC transmission system with a parallel converter topology when a converter lockout fault occurs.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology, wherein the DC power transmission system with a parallel converter topology includes two converter stations, one on the rectifier side and the other on the inverter side. The DC power transmission system of each converter station is bipolar, and each pole adopts a topology structure in which two high and low converters are connected in parallel. During normal operation, the high and low converters operate in parallel. The method comprises:

[0007] Establish communication between the stabilization control device and the DC control and protection equipment of the DC transmission system. The DC control and protection equipment will send signals indicating abnormal shutdown of the converter at the opposite site, sudden power changes at the local pole, and failure of the other pole control dual set.

[0008] The stabilization control device determines that the converter is locked due to a fault based on the collected information and the signal received from the DC control and protection system; the converter locked due to a fault includes the converter on the local side being locked due to a fault and the converter on the opposite side being locked due to a fault; the determination of the converter locked due to a fault also includes determining that the converter is locked due to a faulty pole converter fault caused by the failure of both pole control systems;

[0009] The DC pole control mode is used to determine whether the healthy converter has the power transfer capability when a single converter in the pole fails. The DC fault power loss is calculated based on the maximum transmittable power of the remaining healthy converter after the fault.

[0010] Preferably, the method for determining whether the opposite-side converter is locked due to a fault is:

[0011] When all the following conditions are met, it is determined that the opposite converter is locked due to a fault:

[0012] 1) Receive the "abnormal shutdown" signal of the opposite-side converter sent by the DC control and protection system;

[0013] 2) Receive the "power drop" signal of the fault pole on the local side sent by the DC control and protection system;

[0014] 3) The current or power of any converter in the fault pole on this side suddenly changes and starts.

[0015] Preferably, the step of determining whether the converter has a locked-pole converter fault due to a fault in which both pole control systems are dead includes:

[0016] When the DC control system detects that both sets of control systems of a certain pole are dead, it sends a "double-pole control of the other pole is dead" signal to the stability control system through the normal pole control system. The stability control system combines the electrical quantity characteristics of the converter to determine the fault of the faulty pole converter lockout.

[0017] Preferably, the step of determining whether the converter has a locked-pole converter fault due to a fault in which both pole control systems are dead includes:

[0018] When all of the following conditions are met, it is determined that the converter has a pole converter lockout fault due to a fault in which both pole control systems are dead:

[0019] A. Startup due to sudden change in current or power on the AC side of the converter;

[0020] B. Pdc_≥Pdcrun, where Pdc_ is the active power of the converter AC side 200ms before startup, and Pcdrun is the converter operating power setting;

[0021] C. Pdck < Pdcstop, where Pdck is the real-time active power on the AC side of the converter and Pdcstop is the converter shutdown power setting;

[0022] D. Idck<Idcstop, where Idck is the real-time current on the AC side of the converter and Idcstop is the current setting when the converter is stopped.

[0023] E. The bipolar control crash signal mark position 1 of the converter pole sent by the DC control and protection system.

[0024] Preferably, the determining, based on the DC pole control mode, whether a healthy converter has the power transfer capability when a single converter in the pole fails includes:

[0025] When the following two conditions are met, the converter is judged to be healthy and capable of power transfer, and the transfer is certain to be successful:

[0026] A. The inverter is running before starting;

[0027] B. When the corresponding converter is locked, in the current pole control mode, when the control mode of the pole where the healthy converter is located is at the same level as that of the faulty converter, the healthy converter has the power transfer capability; when the control mode of the pole where the healthy converter is located is at a different level from that of the faulty converter, if the control mode of the pole where the healthy converter is located is bipolar power control, it has the power transfer capability, otherwise it does not have the power transfer capability.

[0028] Preferably, the maximum transmittable power of the remaining healthy converters after the fault is calculated as follows:

[0029] If the healthy converter is in bipolar power control mode, the maximum transmittable power of the healthy converter after the fault is the sum of the maximum transmittable powers of all operating converters;

[0030] If the healthy converter pole is in unipolar power control mode and unipolar current control mode, the maximum transmittable power of the healthy converter pole after the fault is: the minimum value of the sum of the maximum transmittable powers of the remaining operating converters and the sum of the converter operating powers before the fault.

[0031] Preferably, the calculation of the DC fault power loss based on the maximum transmittable power of the remaining healthy converters after the fault includes:

[0032] Pdclos=(Pdc1_+ Pdc2_+ Pdc3_ + Pdc4_) – Ppole1max – Ppole2max,

[0033] Where Pdclost is the DC fault power loss, Pdc1_, Pdc2_, Pdc3_, and Pdc4_ are the steady-state DC transmission power command values ​​of the four converters before the fault, Ppole1max is the maximum transmittable power of pole 1 after the fault, and Ppole2max is the maximum transmittable power of pole 2 after the fault.

[0034] Preferably, the calculation of the DC fault power loss based on the maximum transmittable power of the remaining healthy converters after the fault further includes:

[0035] The DC control and protection system sends an abnormal shutdown signal of the faulty converter to the stabilization device 50ms after the fault occurs. The stabilization device selects the maximum transmittable power of the remaining healthy converters at that moment to calculate the DC fault power loss.

[0036] Preferably, the steady-state DC transmission power command values ​​of the four converters before the fault are determined as follows:

[0037] When the stabilization control device detects a sudden power or current change on the AC side of any converter, it sets the stabilization control device to the startup state and locks the power transmission command value of each converter at the preset time before the stabilization control device is started as the steady-state DC transmission power command value of each converter.

[0038] Preferably, the preset time is 200ms.

[0039] In a second aspect, the present invention provides a fault power loss collaborative calculation system for a DC power transmission system with a parallel converter topology, wherein the DC power transmission system with a parallel converter topology includes two converter stations, one on the rectifier side and the other on the inverter side. The DC power transmission system of each converter station is bipolar, and each pole adopts a topology structure in which two high and low converters are connected in parallel. During normal operation, the high and low converters operate in parallel. The system includes:

[0040] DC control and protection equipment, which establishes communication with the stabilization control device, and newly sends signals indicating abnormal shutdown of the converter at the opposite site, sudden power changes at the local pole, and a double-set shutdown of the other pole control, as well as the maximum transmittable power of each converter after a fault.

[0041] A stabilization control device, configured to determine, based on collected information and a signal received from a DC control and protection system, that a converter is locked due to a fault; the converter being locked due to a fault includes the converter being locked due to a fault on the local side and the converter being locked due to a fault on the opposite side; the determination of the converter being locked due to a fault also includes determining that the converter is locked due to a faulty pole converter failure caused by a double-set freeze of the pole control system; and,

[0042] The DC pole control mode is used to determine whether the healthy converter has the power transfer capability when a single converter in the pole fails. The DC fault power loss is calculated based on the maximum transmittable power of the remaining healthy converter after the fault.

[0043] In a third aspect, the present invention provides a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to perform any one of the methods for collaborative calculation of fault power losses in a direct current transmission system with a parallel converter topology according to the aforementioned method.

[0044] In a fourth aspect, the present invention provides an electronic device comprising one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any one of the methods for collaborative calculation of fault power losses in a direct current transmission system with a parallel converter topology according to the above-mentioned method.

[0045] Through the above technical means, the beneficial effects achieved by the present invention are as follows:

[0046] The present invention solves the problem of inaccurate calculation of fault power loss under complex working conditions such as opposite-side single converter lockout and bipolar control freeze, and achieves the effect of accurately calculating the transmission power loss of a DC transmission system with a parallel converter topology when a converter lockout fault occurs. This is of great significance to the fault analysis, reliability assessment and safe and stable control of the DC transmission system with a parallel converter topology, helps to improve the reliability and stability of the system operation, provides strong support for research and practice in related fields, and promotes the development and improvement of DC transmission technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic flow chart of a method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology provided by an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of the structure of a DC power transmission system with a parallel converter topology provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0050] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show structures and / or processing steps closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0051] It should be emphasized that the term "include / comprises" when used herein refers to the existence of features, elements, steps or components, but does not exclude the existence or addition of one or more other features, elements, steps or components.

[0052] It should also be noted that, unless otherwise specified, the term "connection" herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0053] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0054] It should be emphasized here that the step marks mentioned below do not limit the order of the steps, but it should be understood that the steps can be executed in the order mentioned in the embodiment, or in a different order from the embodiment, or several steps can be executed simultaneously.

[0055] The embodiment of the present invention provides a method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology, which is applied to a DC power transmission system with a parallel converter topology, such as Figure 2 As shown, the DC transmission system consists of two converter stations: the rectifier and inverter stations. Each station features a bipolar DC transmission system, with a topology consisting of two parallel high-voltage and low-voltage converters. During normal operation, the high and low-voltage converters operate in parallel, sharing the power transmission task.

[0056] Example 1

[0057] This embodiment 1 provides a method for collaboratively calculating DC fault power loss in a DC power transmission system with a parallel converter topology. Figure 1 , including the following steps:

[0058] S101. A stabilization control device receives operation and fault information of each converter sent by a DC transmission system.

[0059] The stabilization and control device establishes communication with the DC control and protection equipment of the DC transmission system based on the "GDW 11764-2017 Technical Specification for the Interface of DC Control, Protection and Stabilization Devices of High-Voltage DC Projects". The DC control and protection equipment newly sends abnormal shutdown signals of the converters at the opposite site, sudden power changes at the local pole, and double-set shutdown signals of the other pole.

[0060] S102: When the stabilization control device detects a sudden power change or a sudden current change on the AC side of any converter, the stabilization control device is set to a startup state.

[0061] The stabilization device collects the three-phase voltage and three-phase current on the AC side of the converter and calculates the power on the AC side of the converter. When a sudden power or current change occurs on the AC side of any converter, the stabilization device is set to the startup state.

[0062] S103. Locking the power transmission command values ​​of each converter at a preset time before the stabilization control device is activated as steady-state DC transmission power command values ​​of each converter, for use in calculating the steady-state DC transmission power of the DC transmission system. It should be noted that the steady-state DC transmission power of the DC transmission system is equal to the sum of the steady-state DC transmission power command values ​​of each converter.

[0063] In some embodiments, after the stabilization control device is set to a startup state, the power transmission command value of each converter 200ms before startup is locked as the steady-state DC power transmission command value of each converter.

[0064] S104: Detect whether the converter is locked due to a fault.

[0065] The stabilization control device collects the three-phase voltage and three-phase current on the AC side of the converter, receives the converter unlocking, locking, and abnormal shutdown signals sent by the DC control and protection system, and detects whether the converter on this side is locked due to a fault based on the method disclosed in the Chinese invention patent CN200510123098.0 "Comprehensive Judgment Method for Pole Lockout of DC Transmission System".

[0066] In some embodiments, when the converter of the opposite converter station is locked due to a fault, the converter station on this side cannot sense the fault, and a method for determining the fault locking of the opposite converter station needs to be added.

[0067] Specifically, the opposite-side converter is determined to be locked due to a fault when all of the following conditions are met, including:

[0068] 1) Receive the "abnormal shutdown" signal (ESOF signal) of the opposite-side converter sent by the DC control and protection system;

[0069] 2) Receive the "power drop" signal of the fault pole on the local side sent by the DC control and protection system;

[0070] 3) The current or power of any converter in the fault pole on this side suddenly changes and starts.

[0071] In some embodiments, when the DC control and protection system detects that both sets of a certain pole control system have crashed, it sends a "double-pole control of the other pole has crashed" signal to the stability control system through the normal pole control system. The stability control system combines the electrical quantity characteristics of the converter to determine the fault of the faulty pole converter lockout.

[0072] Specifically, the converter is determined to be actively locked due to a failure of both pole control systems when all of the following conditions are met:

[0073] 1) The converter starts with a sudden change in current or power on the AC side.

[0074] 2) Pdc_≥Pdcrun, where Pdc_ is the active power of the converter on the AC side 200ms before startup, and Pcdrun is the rated operating power of the converter. Considering the possible DC voltage reduction operation, the setting is 0.07 times the rated operating power.

[0075] 3) Pdck<Pdcstop, Pdck is the real-time active power of the converter AC side, Pdcstop is the converter shutdown power setting, which is adjusted to 0.8 times the converter operating power setting.

[0076] 4) Idck<Idcstop, where Idck is the real-time current on the AC side of the converter, and Idcstop is the current constant when the converter is stopped, which is converted according to the converter's stopped power.

[0077] 5) The bipolar control failure signal flag position of the converter pole sent by the DC control and protection system is 1.

[0078] When the above five conditions are met at the same time, it is determined that the converter is actively locked due to the failure of both sets of the pole control system.

[0079] S105: Receive the maximum transmittable power value of each converter after a fault, sent by the DC control and protection system.

[0080] It should be noted that the maximum transmittable power value after each converter fails is calculated by the DC control and protection system when a converter in the DC transmission system is locked due to a fault.

[0081] Since the maximum transmittable power of the converter will change according to the changes in the operating mode of the DC transmission system, in order to ensure the accurate calculation of the power loss of the stabilization and control system after an accident, the DC control and protection system will send the converter ESOF signal to the stabilization and control system only after the maximum transmittable power of the converter is adjusted to the correct level when a DC lockout fault occurs (the converter on this side or the opposite side is locked). After receiving the ESOF signal and determining that the converter is fault locked, the stabilization and control system uses the power command value at the time of fault detection and the maximum transmittable power to calculate the power loss.

[0082] According to the DC pole control mode, the maximum transmittable power of each pole after the converter fault can be calculated according to the method in Table 1, where Pdc1_, Pdc2_, Pdc3_, and Pdc4_ are the operating powers of the four converters before the fault, and Pdc1max, Pdc2max, Pdc3max, and Pdc4max are the maximum transmittable powers of the converters. The calculation principle is as follows:

[0083] (1) If the pole is in bipolar power control mode, the maximum transmittable power of the pole after the accident is the sum of the maximum transmittable powers of all operating converters;

[0084] (2) If the pole is in the unipolar power control mode and the unipolar current control mode, since power can only be transferred to the remaining healthy converters of the pole when the converter of the pole is locked, the maximum transmittable power of the pole after the accident is the minimum value of the sum of the maximum transmittable powers of the remaining operating converters and the sum of the operating powers of the converters before the accident.

[0085] Table 1 Calculation of maximum DC power transferable after a fault under various power control modes

[0086]

[0087] Considering that the maximum transmittable power of the remaining healthy converter after the converter fault is in the dynamic adjustment stage, the DC control system sends the faulty converter ESOF signal when calculating the maximum transmittable power of the remaining healthy converter after the fault (within 50ms after the fault), and updates the maximum transmittable power of the healthy converter at the same time. The stability control system calculates the DC fault power loss based on the maximum transmittable power of the remaining healthy converter after the fault.

[0088] S106: Determine whether the healthy converter has power transfer capability according to the DC pole control mode.

[0089] In this embodiment, whether a healthy converter has the power transfer capability is determined as follows:

[0090] The stability control system obtains the pole control mode, the maximum transferable power of each converter, and the operating power information from the DC control system to determine whether each converter can be transferred. If the following conditions A and B are met, the converter is judged to be transferable and the transfer is considered to be successful.

[0091] A. The inverter is running before starting;

[0092] B. When the corresponding converter is locked, in the current pole control mode, this converter can be switched, as shown in Table 2.

[0093] Table 2 Relationship between power transfer and pole power control mode

[0094]

[0095] Different from the DC transmission system with high-low valve series topology, the DC transmission system with parallel converter topology can transfer power if one converter in the pole fails during "unipolar current control".

[0096] S107. Calculate the power loss after the converter is locked due to a fault. The calculation method is:

[0097] Pdclos=(Pdc1_+ Pdc2_+ Pdc3_ + Pdc4_) – Ppole1max – Ppole2max,

[0098] Where Pdclost is the DC fault power loss, Pdc1_, Pdc2_, Pdc3_, and Pdc4_ are the operating powers of the four converters before the fault, Ppole1max is the maximum transmittable power of pole 1 after the fault, and Ppole2max is the maximum transmittable power of pole 2 after the fault. Ppole1max and Ppole2max are calculated according to Table 1.

[0099] It should be noted that the operating power of the four converters before the fault refers to the steady-state DC transmission power command value of each converter locked in the above step S103.

[0100] Example 2

[0101] In this second embodiment, in conjunction with a high-voltage direct current transmission project with a rated transmission power of 1200 MW, the collaborative calculation method for DC fault power loss in the DC transmission system provided in the above embodiment is used to calculate power loss under different working conditions as follows.

[0102] Under operating condition A, assume a UHVDC transmission project with a rated transmission power of 1200 MW. A bipolar four-valve group operates at 1200 MW, with both poles 1 and 2 using bipolar power control. A fault occurs in converter 1 of pole 1, and the intact valve group operates at full power. During the converter 1 fault, the stabilization control device detects that the corresponding converter transformer current and power meet the sudden change startup conditions. The device enters the startup state and simultaneously locks the power command values ​​for each converter 200 ms before startup as the steady-state DC power command values ​​for each converter. The steady-state DC power command value is equal to the sum of the steady-state DC power command values ​​for each converter, which is 1200 MW. The stabilization control device determines whether the valve group is locked due to a fault based on the unlocking, locking, or abnormal shutdown signals for converter 1 of pole 1 sent by the DC control and protection system and the current and power data collected by the stabilization control device. 50ms after the fault, the abnormal shutdown signal of the pole 1 converter 1 is received. The stabilization control device uses the maximum transmittable power value of the healthy converter at that time, 345MW (1.15 times the overload capacity). Then the stabilization control device determines the power loss amount 50ms after the fault. .

[0103] Under operating condition B, assume a bipolar four-valve group operating at 1000MW, with both poles 1 and 2 controlled by unipolar current. A fault occurs in converter 1 of pole 1 on the opposite side of the converter station, while the four converters on this side remain in operation. The stabilization control device detects that the current and power of the two converter transformers in pole 1 meet the sudden change startup conditions. The device enters the startup state and simultaneously locks the power transfer command values ​​of each converter 200ms before startup as the steady-state DC power transfer command values ​​for each converter. The steady-state DC power transfer is equal to the sum of the steady-state DC power transfer command values ​​of each converter, which is 1000MW. The stabilization control device determines whether the opposite side converter is locked due to a fault based on the abnormal shutdown signal of the opposite side converter in pole 1 sent by the DC control and protection system, the power sudden drop signal on this side, and the current and power of the pole 1 converter collected by the stabilization control device. 50ms after the fault, the abnormal shutdown signal of the opposite pole 1 converter 1 is received. The stabilization control device uses the maximum transmittable power value of each converter of the local pole 1 at that moment, which is 172MW (the opposite pole 1 converter 2 operates at 345MW). The converters of pole 2 do not have the power transfer capability. Then the stabilization control device determines the power loss amount 50ms after the fault. .

[0104] Working condition C, assuming that the bipolar four-valve group operates at 1000MW, poles 1 and 2 are both bipolar power controlled, and a bipolar control crash occurs in pole 1. The DC control protection system locks the two converters of pole 1 after detecting the fault, and sends an "other pole bipolar control crash" signal to the stabilization device through the pole 2 control system 50ms after the fault. The stabilization device comprehensively judges whether a lockout fault has occurred in the pole 1 converter based on the signal and the current and power of the pole 1 converter collected by the stabilization device. 50ms after the fault, the stabilization device receives the maximum transmittable power value of each converter of pole 2, which is 345MW. The stabilization device judges the power loss amount. .

[0105] The embodiment of the present invention realizes the calculation of the power transmission loss due to a DC fault by the stabilization control device, fully considers various operating modes of DC control and protection and the processing solutions under abnormal conditions, meets the requirements of reliability, rapidity, sensitivity and selectivity of the relay protection device, and can effectively reduce the risk of over-cutting or under-cutting the control object of the power grid stability control system due to inaccurate calculation of the power transmission loss due to a DC fault.

[0106] Example 3

[0107] This embodiment 3 provides a fault power loss collaborative calculation system for a DC power transmission system with a parallel converter topology. The DC power transmission system with a parallel converter topology is Figure 2 The DC transmission system shown in the figure includes two converter stations: the rectifier and inverter stations. Each converter station has a bipolar DC transmission system, with each pole adopting a topology structure in which two high-voltage and low-voltage converters are connected in parallel. During normal operation, the high-voltage and low-voltage converters operate in parallel. The collaborative computing system includes:

[0108] DC control and protection equipment: This equipment establishes communication with the stabilization and control device. It also sends signals indicating abnormal shutdown of the converter at the opposite site, sudden power changes at the local pole, and a shutdown of the other pole control dual set. It also sends the maximum transmittable power of each converter after a fault.

[0109] A stabilization control device, configured to determine, based on collected information and a signal received from a DC control and protection system, that a converter is locked due to a fault; the converter being locked due to a fault includes the converter being locked due to a fault on the local side and the converter being locked due to a fault on the opposite side; the determination of the converter being locked due to a fault also includes determining that the converter is locked due to a faulty pole converter failure caused by a double-set freeze of the pole control system; and,

[0110] The DC pole control mode is used to determine whether the healthy converter has the power transfer capability when a single converter in the pole fails. The DC fault power loss is calculated based on the maximum transmittable power of the remaining healthy converter after the fault.

[0111] It is worth pointing out that this system embodiment corresponds to the above-mentioned method embodiment, and the implementation methods of the above-mentioned method embodiment are applicable to this system embodiment and can achieve the same or similar technical effects, so they will not be described in detail here.

[0112] Example 4

[0113] This embodiment 4 provides a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to perform any one of the methods for collaboratively calculating fault power losses in a DC transmission system with a parallel converter topology according to the above-mentioned embodiments.

[0114] Example 5

[0115] This embodiment 5 provides an electronic device, including one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any one of the methods for collaborative calculation of fault power losses in a direct current transmission system with a parallel converter topology according to the above-mentioned embodiments.

[0116] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0117] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0118] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0119] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology, wherein the DC power transmission system with a parallel converter topology comprises two converter stations, one on the rectifier side and the other on the inverter side. Each converter station DC power transmission system is bipolar, and each pole adopts a topology structure in which two high-side and low-side converters are connected in parallel. During normal operation, the high-side and low-side converters operate in parallel. The method comprises: Establish communication between the stabilization control device and the DC control and protection equipment of the DC transmission system. The DC control and protection equipment will send signals indicating abnormal shutdown of the converter at the opposite site, sudden power changes at the local pole, and failure of the other pole control dual set. The stabilization control device determines that the converter is locked due to a fault based on the collected information and the signal received from the DC control and protection system; the converter locked due to a fault includes the converter on the local side being locked due to a fault and the converter on the opposite side being locked due to a fault; the determination of the converter locked due to a fault also includes determining that the converter is locked due to a faulty pole converter fault caused by the failure of both pole control systems; The DC pole control mode is used to determine whether the healthy converter has the power transfer capability when a single converter in the pole fails. The DC fault power loss is calculated based on the maximum transmittable power of the remaining healthy converter after the fault.

2. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 1, characterized in that: The judgment method of the opposite side converter being locked due to a fault is: When all the following conditions are met, it is determined that the opposite converter is locked due to a fault: 1) Receive the "abnormal shutdown" signal of the opposite-side converter sent by the DC control and protection system; 2) Receive the "power drop" signal from the DC control and protection system indicating the faulty pole on the local side; 3) The current or power of any converter in the fault pole on this side suddenly changes and starts.

3. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 1, characterized in that: The method of judging a converter locked fault due to a fault in a pole control system dual-set shutdown of the converter includes: When the DC control system detects that both control systems of a certain pole have failed, it sends a "double-pole control failure of the other pole" signal to the stability control system through the normal pole control system. The stability control system then uses the electrical characteristics of the converter to determine the faulty converter lockout fault.

4. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 3, characterized in that: The method of judging a converter locked fault due to a fault in a pole control system dual-set shutdown of the converter includes: When all of the following conditions are met, it is determined that the converter has a pole converter lockout fault due to a fault in which both pole control systems are dead: A. Startup due to sudden change in current or power on the AC side of the converter; B. Pdc_≥Pdcrun, where Pdc_ is the active power of the converter AC side 200ms before startup, and Pcdrun is the converter operating power setting; C. Pdck < Pdcstop, where Pdck is the real-time active power on the AC side of the converter and Pdcstop is the converter shutdown power setting; D. Idck<Idcstop, where Idck is the real-time current on the AC side of the converter and Idcstop is the current setting when the converter is stopped. E. The bipolar control crash signal mark position 1 of the converter pole sent by the DC control and protection system.

5. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 1, characterized in that: The method of judging whether a healthy converter has the power transfer capability when a single converter in a pole fails according to the DC pole control mode includes: When the following two conditions are met, the converter is judged to be healthy and capable of power transfer, and the transfer is certain to be successful: A. The inverter is running before starting; B. When the corresponding converter is locked, in the current pole control mode, when the control mode of the pole where the healthy converter is located is at the same level as that of the faulty converter, the healthy converter has the power transfer capability; when the control mode of the pole where the healthy converter is located is at a different level from that of the faulty converter, if the control mode of the pole where the healthy converter is located is bipolar power control, it has the power transfer capability, otherwise it does not have the power transfer capability.

6. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 5, characterized in that: The maximum transmittable power of the remaining healthy converter after the fault is calculated as follows: If the healthy converter is in bipolar power control mode, the maximum transmittable power of the healthy converter after the fault is the sum of the maximum transmittable powers of all operating converters; If the healthy converter pole is in unipolar power control mode and unipolar current control mode, the maximum transmittable power of the healthy converter pole after the fault is: the minimum value of the sum of the maximum transmittable powers of the remaining operating converters and the sum of the converter operating powers before the fault.

7. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 6, characterized in that: The calculation of the DC fault power loss based on the maximum transmittable power of the remaining healthy converter after the fault includes: Pdclos=(Pdc1_+ Pdc2_+ Pdc3_ + Pdc4_) – Ppole1max – Ppole2max, Where Pdclost is the DC fault power loss, Pdc1_, Pdc2_, Pdc3_, and Pdc4_ are the steady-state DC transmission power command values ​​of the four converters before the fault, Ppole1max is the maximum transmittable power of pole 1 after the fault, and Ppole2max is the maximum transmittable power of pole 2 after the fault.

8. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 7, characterized in that: The calculation of the DC fault power loss based on the maximum transmittable power of the remaining healthy converter after the fault further includes: The DC control and protection system sends an abnormal shutdown signal of the faulty converter to the stabilization device 50ms after the fault occurs. The stabilization device selects the maximum transmittable power of the remaining healthy converters at that moment to calculate the DC fault power loss.

9. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 7, characterized in that: The method for determining the steady-state DC transmission power command values ​​of the four converters before the fault is as follows: When the stabilization control device detects a sudden power or current change on the AC side of any converter, it sets the stabilization control device to the startup state and locks the power transmission command value of each converter at the preset time before the stabilization control device is started as the steady-state DC transmission power command value of each converter.

10. The method for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claim 9, characterized in that: The preset time is 200ms.

11. A fault power loss collaborative calculation system for a DC power transmission system with a parallel converter topology, wherein the DC power transmission system with a parallel converter topology comprises two converter stations, one on the rectifier side and the other on the inverter side. Each converter station DC power transmission system is bipolar, and each pole adopts a topology structure in which two high and low converters are connected in parallel. During normal operation, the high and low converters operate in parallel, characterized in that: The computing system includes: DC control and protection equipment, which establishes communication with the stabilization control device, and newly sends signals indicating abnormal shutdown of the converter at the opposite site, sudden power changes at the local pole, and a double-set shutdown of the other pole control, as well as the maximum transmittable power of each converter after a fault. A stabilization control device, configured to determine, based on collected information and a signal received from a DC control and protection system, that a converter is locked due to a fault; the converter being locked due to a fault includes the converter being locked due to a fault on the local side and the converter being locked due to a fault on the opposite side; the determination of the converter being locked due to a fault also includes determining that the converter is locked due to a faulty pole converter failure caused by a double-set freeze of the pole control system; and, The DC pole control mode is used to determine whether the healthy converter has the power transfer capability when a single converter in the pole fails. The DC fault power loss is calculated based on the maximum transmittable power of the remaining healthy converter after the fault.

12. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions, which, when executed by a computing device, cause the computing device to perform any one of the methods for collaboratively calculating fault power loss in a DC power transmission system with a parallel converter topology according to claims 1 to 10.

13. An electronic device, characterized in that: include, One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any one of the methods for collaboratively calculating fault power losses in a DC transmission system with a parallel converter topology according to claims 1 to 10.

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