Judgment method and system for interlocking commutation failure of alternating-current and direct-current hybrid power grid

Abstract

The invention discloses a method and a system for judging interlocking commutation failure of an alternating-current and direct-current hybrid power grid, and belongs to the technical field of safety and stability analysis and control of large power grids. The judgment method provided by the invention comprises the following steps: determining a transformation relation between the voltage variation of a converter bus and reactive power for an alternating-current and direct-current hybrid power grid; according to the monitoring data of the AC / DC hybrid power grid, calculating a voltage value of a converter bus based on the transformation relation, and comparing the voltage value of the converter bus with a critical converter bus voltage value to obtain a comparison result; and based on the comparison result, determining whether the alternating-current and direct-current hybrid power grid fails or not. According to the method, the voltage drop amount of the commutation bus is calculated from the perspective of mechanism by starting from the quasi-steady-state model of the direct-current system, so that the cascading failure mechanism of the alternating-current and direct-current hybrid system after the failure can be revealed, whether multi-loop direct-current successive commutation failure exists or not can be quickly predicted, the method does not depend on a power grid operation mode, and a theoretical basis is provided for subsequent control.

Description

Technical Field

[0001] The present invention relates to the technical field of large power grid security and stability analysis and control, and more specifically, to a method and system for determining interlocking commutation failure in an AC / DC hybrid power grid. Background Art

[0002] Currently, most of my country's existing high-voltage, long-distance direct current (DC) transmission systems are based on LCC-HVDC. The rapid development of ultra-high voltage DC transmission has led to a sharp shift in the conflict between strong DC and weak AC. Because LCC-HVDC's commutation devices are thyristors, semi-controlled devices that cannot shut down autonomously, commutation failure has become one of the most common faults in DC transmission systems.

[0003] With the gradual commissioning of numerous DC transmission projects, scenarios with densely populated DC feed-ins are increasingly emerging. The close coupling between DC lines can easily lead to commutation failures occurring sequentially across multiple lines, a phenomenon known as cascading commutation failures. These commutation failures can cause significant instantaneous power shortfalls in the DC transmitting and receiving systems. Insufficient reactive power support can even lead to voltage stability issues and system-level cascading failures, seriously threatening the safe and stable operation of the system.

[0004] As the scale of AC / DC hybrid power grids increases, they exhibit complex characteristics of strong nonlinearity and strong coupling. In scenarios where multiple DC loops are fed into AC systems, undesirable interactions between converter buses are a major cause of cascading commutation failures. To quantify this mutual influence between converter buses, the International Conference on Large Electric Systems (CIGRE) proposed the Multi-Infeed Interaction Factor (MIIF) to characterize the closeness of the connection between converter buses. By analyzing the relationship between converter station AC bus voltage drop and system node impedance, a node impedance expression for converter station AC bus voltage drop can be established. Using the critical commutation failure voltage drop or the critical DC power interruption voltage drop as the criterion, the critical fault impedance boundary of a single converter station can be delineated on the grid topology diagram based on the node impedance matrix. Subsequently, researchers improved on MIIF and proposed an AC / DC interaction factor to describe the strength of the coupling relationship between the AC node and the DC commutation bus, expanding the scope of application of MIIF from DC-DC to AC-DC. Based on this, the AC / DC interaction factor and critical interaction factor between the fault node in the AC system and the DC commutation bus are compared to determine commutation failures caused by voltage distortion. The above method is mainly used to determine local or simultaneous commutation failures, but it is still insufficient for determining chained commutation failures. The method based on MIIF and its generalized voltage interaction factor focuses on the tightness of the coupling between the fault node and the inverter station commutation bus. By comparing the voltage interaction factor between the fault point and the commutation bus with the corresponding critical value during the fault, it is determined whether commutation failure and chained commutation failure will occur.

[0005] Research has found that the amount of reactive power exchanged between different DC systems is also an important factor affecting the successive commutation failures of multiple DC systems. During the chain commutation failure process, one manifestation of the commutation failure propagation is that the DC control system takes effect, causing the flow of reactive power, resulting in reactive power shortages in different DC inverter stations, causing voltage drops and leading to successive commutation failures.

[0006] Therefore, it is urgent to deeply explore and study the method of judging the failure of multiple DC commutation cycles in AC / DC hybrid systems. Summary of the Invention

[0007] In response to the above problems, the present invention proposes a method for determining interlocking commutation failure in an AC / DC hybrid power grid, comprising:

[0008] For AC / DC hybrid power grids, determine the conversion relationship between commutation bus voltage variation and reactive power;

[0009] calculating a voltage value of a commutation bus according to the monitoring data of the AC / DC hybrid power grid and based on the transformation relationship, and comparing the voltage value of the commutation bus with a critical commutation bus voltage value to obtain a comparison result;

[0010] Based on the comparison result, it is determined whether the AC / DC hybrid power grid fails.

[0011] Optionally, the calculation formula for the voltage value of the commutation bus is as follows:

[0012] When t≥t f +t dur hour:

[0013]

[0014] When t <t f +t dur hour:

[0015]

[0016] Where t is time, t f is the fault time, t dur is the fault duration, is the voltage value of the commutation bus, S ac is the short-circuit capacity, Q cik is the reactive compensation of the DC inverter side filter, Q acik is the reactive power exchange between the inverter and the AC system, Q′ kj is the reactive exchange power between the kth converter station and the adjacent jth converter station after the fault, Q dik The reactive power consumed by the kth converter station, Q cikis the reactive compensation of the filter on the DC inverter side, j is the jth converter station on the DC inverter side, k is the kth converter station on the DC inverter side, It is the per-unit voltage value when the fault is cleared.

[0017] Optionally, determining whether the AC / DC hybrid power grid fails based on the comparison result includes:

[0018] When comparing the results:

[0019] Commutation bus voltage Determine if commutation failure occurs on the commutation bus.

[0020] Optional, The calculation formula is as follows:

[0021]

[0022] Among them, X k % is the per unit reactance of the converter transformer, is the per-unit value of the DC operating current, and β is the leading trigger angle of the commutation bus.

[0023] In another aspect, the present invention further provides a system for determining interlocking commutation failure in an AC / DC hybrid power grid, comprising:

[0024] An initialization unit is used to determine the conversion relationship between the commutation bus voltage variation and reactive power for an AC / DC hybrid power grid;

[0025] a comparing unit, which calculates a voltage value of a commutation bus according to the monitoring data of the AC / DC hybrid power grid and based on the transformation relationship, and compares the voltage value of the commutation bus with a critical commutation bus voltage value to obtain a comparison result;

[0026] A judgment unit is used to determine whether the AC / DC hybrid power grid has failed based on the comparison result.

[0027] Optionally, the calculation formula for the voltage value of the commutation bus is as follows:

[0028] When t≥t f +t dur hour:

[0029]

[0030] When t <t f +t dur hour:

[0031]

[0032] Where t is time, t f is the fault time, t duris the fault duration, is the voltage value of the commutation bus, S ac is the short-circuit capacity, Q cik is the reactive compensation of the DC inverter side filter, Q acik is the reactive power exchange between the inverter and the AC system, Q′ kj is the reactive exchange power between the kth converter station and the adjacent jth converter station after the fault, Q dik The reactive power consumed by the kth converter station, Q cik is the reactive compensation of the filter on the DC inverter side, j is the jth converter station on the DC inverter side, k is the kth converter station on the DC inverter side, It is the per-unit voltage value when the fault is cleared.

[0033] Optionally, determining whether the AC / DC hybrid power grid fails based on the comparison result includes:

[0034] When comparing the results:

[0035] Commutation bus voltage Determine if commutation failure occurs on the commutation bus.

[0036] Optional, The calculation formula is as follows:

[0037]

[0038] Among them, X k % is the per unit reactance of the converter transformer, is the per-unit value of the DC operating current, and β is the leading trigger angle of the commutation bus.

[0039] In yet another aspect, the present invention further provides a computing device comprising: one or more processors;

[0040] a processor for executing one or more programs;

[0041] When the one or more programs are executed by the one or more processors, the above-described method is implemented.

[0042] In another aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, the method described above is implemented.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a method for determining chain commutation failure in an AC / DC hybrid power grid, comprising: determining, for the AC / DC hybrid power grid, a conversion relationship between a commutation bus voltage change and reactive power; calculating, based on the conversion relationship and monitoring data of the AC / DC hybrid power grid, a commutation bus voltage value; comparing the commutation bus voltage value with a critical commutation bus voltage value to obtain a comparison result; and determining, based on the comparison result, whether the AC / DC hybrid power grid has failed. Starting from a quasi-steady-state model of the DC system, the present invention calculates the commutation bus voltage drop from a mechanistic perspective, which is beneficial for revealing the chain failure mechanism of the AC / DC hybrid system after a fault, and rapidly predicting whether there are multiple DC commutation failures. This method is independent of the grid operation mode and provides a theoretical basis for subsequent control. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a flow chart of the method of the present invention;

[0046] Figure 2 Schematic diagram of a four-area AC / DC hybrid system according to an embodiment of the method of the present invention;

[0047] Figure 3 A schematic diagram of a multi-infeed DC system according to an embodiment of the method of the present invention;

[0048] Figure 4 Schematic diagram of an equivalent circuit of an inverter commutation process according to an embodiment of the method of the present invention;

[0049] Figure 5 A schematic diagram of a judgment flow of an embodiment of the method of the present invention;

[0050] Figure 6 A schematic diagram of a turn-off angle curve in an embodiment of the method of the present invention;

[0051] Figure 7 It is a structural diagram of the system of the present invention. DETAILED DESCRIPTION

[0052] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0053] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0054] Example 1:

[0055] The present invention proposes a method for judging the failure of interlocking commutation in AC / DC hybrid power grid. Figure 1 Shown, including:

[0056] Step 1: For an AC / DC hybrid power grid, determine the conversion relationship between the commutation bus voltage variation and reactive power;

[0057] Step 2: Calculate the voltage value of the commutation bus based on the conversion relationship according to the monitoring data of the AC / DC hybrid power grid, and compare the voltage value of the commutation bus with the critical commutation bus voltage value to obtain a comparison result;

[0058] Step 3: Based on the comparison result, determine whether the AC / DC hybrid power grid fails.

[0059] The calculation formula for the voltage value of the commutation bus is as follows:

[0060] When t≥t f +t dur hour:

[0061]

[0062] When t <t f +t dur hour:

[0063]

[0064] Where t is time, t f is the fault time, t dur is the fault duration, is the voltage value of the commutation bus, S ac is the short-circuit capacity, Q cik is the reactive compensation of the DC inverter side filter, Q acik is the reactive power exchange between the inverter and the AC system, Q′ kj is the reactive exchange power between the kth converter station and the adjacent jth converter station after the fault, Q dik The reactive power consumed by the kth converter station, Q cik is the reactive compensation of the filter on the DC inverter side, j is the jth converter station on the DC inverter side, k is the kth converter station on the DC inverter side, It is the per-unit voltage value when the fault is cleared.

[0065] Wherein, determining whether the AC / DC hybrid power grid fails based on the comparison result includes:

[0066] When comparing the results:

[0067] Commutation bus voltage Determine if commutation failure occurs on the commutation bus.

[0068] in, The calculation formula is as follows:

[0069]

[0070] Among them, X k % is the per unit reactance of the converter transformer, is the per-unit value of the DC operating current, and β is the leading trigger angle of the commutation bus.

[0071] The present invention will be further described below with reference to specific implementation cases:

[0072] According to the actual power grid structure in my country, a four-region AC / DC hybrid power system is constructed, such as Figure 2 For the receiving system in area 2, a three-phase n-1 fault occurred within the regional system, causing multiple DC commutation failures. The commutation bus voltage drop was the direct cause of the DC commutation failure, which was closely related to the reactive power exchange between the inverter and the system.

[0073] For Figure 3 For the multi-DC infeed system shown, the DC quasi-steady-state model is expressed as the following series of formulas.

[0074] Among them, the no-load voltages of the DC transmitting and receiving ends are:

[0075]

[0076] Among them, U r0 、U i0 are the no-load voltages of the DC rectifier side and the inverter side respectively; N r 、N i is the number of 6-pulse converters per pole in the rectifier station and inverter station; T r 、T i is the commutation ratio of the rectifier station and the inverter station; U r 、U i is the commutation bus voltage on the rectifier and inverter sides.

[0077] The voltages on the DC rectifier and inverter sides are:

[0078]

[0079] Where, X cr and X ci I is the commutation reactance of the rectifier station and inverter station; d is a direct current.

[0080] The relationship between the voltage and current at the DC sending and receiving ends is:

[0081] U dr -U di =R d I d

[0082] Where R d is the DC line resistance.

[0083] The power factor angles at the sending and receiving ends are:

[0084]

[0085] The active power on both sides of the DC is:

[0086]

[0087] The reactive power exchanged between the DC rectifier station and the inverter station and the system is:

[0088]

[0089] Where B r 、B i It is the filter susceptance of DC rectifier station and inverter station.

[0090] For example Figure 3 In the AC / DC hybrid receiving-end grid with multiple DC feeds shown, whether a cascading DC commutation failure will occur after an AC system fault n-1 occurs can be determined by the relationship between the inverter station and the AC system reactive power. For the kth inverter in the system, the relationship between the inverter and the AC system reactive power can be inferred as follows:

[0091] Before an AC fault n-1 occurs in the system, the relationship between the reactive power of the kth inverter in the receiving system and the AC system is expressed as:

[0092]

[0093] Therefore, we can get:

[0094]

[0095] Where Q dik is the reactive power consumption of the kth inverter, Q acik is the reactive power exchange between the inverter and the AC system, Q ckThe reactive power provided by the filter of the k-th inverter station, ΔQ kj is the reactive exchange power between the kth converter station and the adjacent jth converter station.

[0096] After a fault occurs in the AC system, the differential equation of the DC dynamic process is:

[0097]

[0098] Where, L r , L i , L d They are the inductance of the smoothing reactor on the rectifier side, the inverter side and the DC line inductance respectively.

[0099] The voltage drop of the commutation bus after a fault is dynamic and is related to the change in the reactive power exchange of the system. The reactive power change is shown in the following formula:

[0100]

[0101] To analyze the reactive power variation in the above formula, the following variables need to be analyzed:

[0102] Reactive power Q' provided by the filter after the fault ck

[0103] because

[0104] You can get:

[0105] Where U Lik is the commutation bus voltage, which is the rated value U before the fault LikN .

[0106] Therefore, the change in reactive power provided by the filter can be obtained as:

[0107]

[0108] So we can get:

[0109] Converter reactive power consumption Q' after fault dik

[0110] The equivalent circuit of the inverter commutation process is as follows: Figure 4 As shown, the inverter satisfies the following equation:

[0111]

[0112] i a +i b =I di

[0113] Integrating both sides yields:

[0114]

[0115] In the initial state, i b (α i )=0

[0116] When commutation ends: i b (α i +μ i )=I di (α i +μ i )

[0117] When the DC system is operating normally: I di (α i )=I di (α i +μ i )=I di

[0118] Therefore, we can get:

[0119] The power factor angle can be obtained as:

[0120] The reactive power consumed by the kth inverter is:

[0121]

[0122] The DC voltage is:

[0123]

[0124] The relationship between the reactive power consumed by the kth inverter and the voltage is as follows:

[0125]

[0126] Therefore, the reactive power consumed by the kth inverter after the fault can be calculated as follows:

[0127]

[0128] Through the above derivation of reactive power exchange in AC and DC systems, the relationship between the commutation bus voltage change and the AC and DC reactive power exchange is further analyzed as follows:

[0129]

[0130] Among them, S ac is the short-circuit capacity.

[0131] There is a transient relationship between the commutation bus voltage and the reactive exchange amount. The time sequence is divided into two periods: from after the fault to before the fault is cleared and after the fault is cleared. The commutation bus voltage can be written as:

[0132]

[0133] Among them, U Likf is the voltage after short circuit.

[0134] The reactive power exchange with the AC system is:

[0135]

[0136] The commutation bus voltage change can be further obtained:

[0137]

[0138] Therefore, the relationship between the commutation bus voltage change and reactive power is established.

[0139] The solution calculation is performed in two stages:

[0140] (1)t≥t f +t dur

[0141]

[0142] (2)t<t f +t dur

[0143]

[0144] The above formulas can be transformed into:

[0145] (1)t≥t f +t dur

[0146]

[0147] Calculation yields:

[0148]

[0149] (2)t<t f +t dur

[0150]

[0151] Calculation yields:

[0152]

[0153] The commutation bus voltages in these two phases reflect the bus voltage changes before and after the fault is cleared. After an AC fault occurs, the voltage drops of multiple commutation buses can be determined from the perspective of reactive power exchange. When a commutation bus voltage drops below a certain limit, commutation failure is determined.

[0154] Where, the instantaneous fault voltage is:

[0155]

[0156] Assuming that the fault point occurs at the AC bus m, the interaction factor is:

[0157]

[0158] In the above formula, Z km is the mutual impedance between the kth commutation bus and the AC bus m; Z mm is the self-impedance of the AC bus m.

[0159] The voltage value corresponding to the minimum arc extinction angle of the inverter is:

[0160] The critical commutation voltage value per unit of the p-th commutation bus voltage is:

[0161]

[0162] in is the critical commutation voltage per unit value of the p-th commutation bus voltage, X k % is the per unit reactance of the converter transformer, β is the leading trigger angle of the commutation bus, is the per-unit value of the DC operating current.

[0163] when When the commutation bus fails, the judgment process is as follows: Figure 5 shown.

[0164] The present invention is applied to a provincial power grid in my country. The calculation data is based on the annual calculation data of the provincial power grid. The power grid has four UHV DC feeds, two of which are layered DC with two high and low converter stations. Therefore, the receiving-end power grid has six converter stations. At the same time, the receiving-end power grid also has UHV AC feed-in power. The AC fault is set as follows: a UHV AC line n-1 of the provincial power grid fails in the vicinity of the low-converter 1 converter station. After the failure, whether a commutation failure will occur is predicted. The calculated converter station voltage and critical voltage are shown in Table 1:

[0165] Table 1

[0166] Converter Station The lowest voltage point after the fault (pu) Critical voltage (pu) Low Exchange 1 0.6 0.65 High Exchange 1 0.83 0.85 Low Swap 2 0.4 0.5 High Change 2 0.67 0.75 East Exchange 0.75 0.8 Qinghuan 0.79 0.8

[0167] By comparison, it is determined that the four DC circuits will have commutation failure at different times. Compared with the time domain simulation results, the effectiveness of this method is verified. The four DC circuit turn-off angle curves are shown in Figure 2. Figure 6 shown.

[0168] Example 2:

[0169] The present invention also proposes a system 200 for determining interlocking commutation failure in an AC / DC hybrid power grid. Figure 7 Shown, including:

[0170] The initialization unit 201 is used to determine the conversion relationship between the commutation bus voltage variation and reactive power for the AC / DC hybrid power grid;

[0171] A comparison unit 202 calculates a voltage value of a commutation bus according to the monitoring data of the AC / DC hybrid power grid and based on the transformation relationship, and compares the voltage value of the commutation bus with a critical commutation bus voltage value to obtain a comparison result;

[0172] The judgment unit 203 is configured to determine whether the AC / DC hybrid power grid has failed based on the comparison result.

[0173] The calculation formula for the voltage value of the commutation bus is as follows:

[0174] When t≥t f +t dur hour:

[0175]

[0176] When t <t f +t dur hour:

[0177]

[0178] Where t is time, t f is the fault time, t dur is the fault duration, is the voltage value of the commutation bus, S ac is the short-circuit capacity, Q cik is the reactive compensation of the DC inverter side filter, Q acik is the reactive power exchange between the inverter and the AC system, Q′ kj is the reactive exchange power between the kth converter station and the adjacent jth converter station after the fault, Q dik The reactive power consumed by the kth converter station, Q cik is the reactive compensation of the filter on the DC inverter side, j is the jth converter station on the DC inverter side, k is the kth converter station on the DC inverter side, It is the per-unit voltage value when the fault is cleared.

[0179] Wherein, determining whether the AC / DC hybrid power grid fails based on the comparison result includes:

[0180] When comparing the results:

[0181] Commutation bus voltage Determine if commutation failure occurs on the commutation bus.

[0182] in, The calculation formula is as follows:

[0183]

[0184] Among them, X k % is the per unit reactance of the converter transformer, is the per-unit value of the DC operating current, and β is the leading trigger angle of the commutation bus.

[0185] The present invention fully considers factors such as the reactive power consumption of the DC inverter after an AC system fault, the amount of DC reactive compensation, and the reactive interaction between adjacent multi-circuit DC systems. The reactive power exchange between the AC and DC systems after the fault is obtained through an analytical method, and the commutation bus voltage is derived from the reactive power exchange amount. By comparing the critical voltage value corresponding to the minimum arcing angle, it is determined whether a chain commutation failure will occur in the multi-input DC.

[0186] Starting from the quasi-steady-state model of the DC system, the present invention calculates the commutation bus voltage drop from a mechanism perspective, which is conducive to revealing the cascading failure mechanism of the AC / DC hybrid system after a fault, and quickly predicting whether there are multiple DC commutation failures in succession. It is independent of the grid operation mode and provides a theoretical basis for subsequent control.

[0187] Example 3:

[0188] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the method in the above embodiment.

[0189] Example 4:

[0190] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space that stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiment.

[0191] It will be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention may be implemented in various computer languages, for example, the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0192] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, 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 flowcharts and / or block diagrams. 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.

[0193] 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.

[0194] 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.

[0195] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0196] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for determining interlocking commutation failure in an AC / DC hybrid power grid, characterized in that: include: For AC / DC hybrid power grids, determine the conversion relationship between commutation bus voltage variation and reactive power; calculating a voltage value of a commutation bus according to the monitoring data of the AC / DC hybrid power grid and based on the transformation relationship, and comparing the voltage value of the commutation bus with a critical commutation bus voltage value to obtain a comparison result; Based on the comparison result, it is determined whether the AC / DC hybrid power grid fails.

2. The judgment method according to claim 1, characterized in that: The calculation formula for calculating the voltage value of the commutation bus is as follows: When t≥t f +t dur hour: When t <t f +t dur hour: Where t is time, t f is the fault time, t dur is the fault duration, is the voltage value of the commutation bus, S ac is the short-circuit capacity, Q cik is the reactive compensation of the DC inverter side filter, Q acik is the reactive power exchange between the inverter and the AC system, Q′ kj is the reactive exchange power between the kth converter station and the adjacent jth converter station after the fault, Q dik The reactive power consumed by the kth converter station, Q cik is the reactive compensation of the filter on the DC inverter side, j is the jth converter station on the DC inverter side, k is the kth converter station on the DC inverter side, It is the per-unit voltage value when the fault is cleared.

3. The judgment method according to claim 1, characterized in that: The determining whether the AC / DC hybrid power grid fails based on the comparison result includes: When comparing the results: Commutation bus voltage ≤pth critical commutation bus voltage value When , it is determined that the commutation bus fails.

4. The judgment method according to claim 3, characterized in that: described The calculation formula is as follows: Among them, X k % is the per unit reactance of the converter transformer, is the per-unit value of the DC operating current, and β is the leading trigger angle of the commutation bus.

5. A system for determining interlocking commutation failure in an AC / DC hybrid power grid, characterized in that: include: An initialization unit is used to determine the conversion relationship between the commutation bus voltage variation and reactive power for an AC / DC hybrid power grid; a comparing unit, which calculates a voltage value of a commutation bus according to the monitoring data of the AC / DC hybrid power grid and based on the transformation relationship, and compares the voltage value of the commutation bus with a critical commutation bus voltage value to obtain a comparison result; A judgment unit is used to determine whether the AC / DC hybrid power grid has failed based on the comparison result.

6. The judgment system according to claim 5, characterized in that: The calculation formula for calculating the voltage value of the commutation bus is as follows: When t≥t f +t dur hour: When t <t f +t dur hour: Where t is time, t f is the fault time, t dur is the fault duration, is the voltage value of the commutation bus, S ac is the short-circuit capacity, Q cik is the reactive compensation of the DC inverter side filter, Q acik is the reactive power exchange between the inverter and the AC system, Q′ kj is the reactive exchange power between the kth converter station and the adjacent jth converter station after the fault, Q dik The reactive power consumed by the kth converter station, Q cik is the reactive compensation of the filter on the DC inverter side, j is the jth converter station on the DC inverter side, k is the kth converter station on the DC inverter side, It is the per-unit voltage value when the fault is cleared.

7. The judgment system according to claim 5, characterized in that: The determining whether the AC / DC hybrid power grid fails based on the comparison result includes: When comparing the results: Commutation bus voltage ≤pth critical commutation bus voltage value When , it is determined that the commutation bus fails.

8. The judgment system according to claim 7, characterized in that: described The calculation formula is as follows: Among them, X k % is the per unit reactance of the converter transformer, is the per-unit value of the DC operating current, and β is the leading trigger angle of the commutation bus.

9. A computer device, characterized in that: include: one or more processors; a processor for executing one or more programs; When the one or more programs are executed by the one or more processors, the method according to any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed, the method according to any one of claims 1 to 4 is implemented.

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