Differential protection test method and system for converter transformer valve group in fault process simulation

Abstract

This invention provides a differential protection testing method and system for converter transformer valve groups based on fault process simulation, belonging to the technical field of differential protection testing for converter transformer valve groups. The testing method includes parameter configuration via human-machine interaction; acquiring status data of the DC protection device during normal operation; and, by acquiring data from the DC protection device during normal operation and fault data under various fault conditions, discretizing this data, and then simultaneously sending the AC-side and DC-side discrete data to the DC protection device for sequential differential protection characteristic testing. This enables the testing of the valve group's differential protection characteristics, ensuring more reliable operation of the DC protection device and improving the safety of the protection system.

Description

Technical Field

[0001] This invention relates to the field of differential protection testing technology for converter variable valve groups, and specifically to a differential protection testing method and system for converter variable valve groups that simulates fault processes. Background Technology

[0002] Currently, secondary protection systems lack effective on-site performance testing methods and equipment. Effective on-site testing and experiments cannot be conducted before commissioning or during operation, making it impossible to determine the actual performance and operating conditions of DC transformers and protection equipment. DC protection testing primarily involves RTDS system digital simulation experiments conducted by equipment manufacturers before delivery or PSCAD system digital simulation experiments conducted at research institutes to test various performance aspects of the protection system. Because of the complex coupling relationships between DC transmission control and protection equipment, fault location cannot be timely and effective when equipment malfunctions. After on-site protection software upgrades or device board replacements, a reliable method is needed to verify and test the correctness of the software logic and input / output signals when converter valves fail. Existing DC protection on-site testing can only be performed through simple incremental testing. For some special DC protection requirements, especially those requiring simultaneous AC and DC fault application such as valve short-circuit protection, there are currently no means to achieve on-site testing; testing can only be conducted through dynamic simulation experiments in the laboratory.

[0003] Valve short-circuit protection is used to detect valve short-circuit faults and phase-to-phase faults on the converter transformer valve side, preventing the converter valve from being subjected to overstress during a short circuit. It works by measuring the currents in the Y and D windings on the converter transformer valve side, as well as the valve's high and low voltage outlet currents. The maximum value of the valve-side current is compared to the maximum value of the DC current. Under normal operating conditions, the differential current is very small. If the AC-side current is significantly higher than the DC current, it indicates a fault has occurred, and the protection immediately activates.

[0004] Currently, valve short-circuit protection simultaneously acquires the analog output current value of the conventional AC side current transformer and the digital output current value of the DC side electronic current transformer to complete differential calculations. Since the DC side current lacks a phase concept, the maximum value is used for differential current judgment. Under normal circumstances, the impact of asynchrony on valve short-circuit protection is negligible. However, under fault conditions, the three-phase currents on the AC side are no longer symmetrical, resulting in a difference between the maximum value of the AC three-phase current and the maximum value of the DC current. Under synchronous conditions, the valve short-circuit protection will operate immediately. Under asynchronous conditions, it does not affect the correctness of the valve short-circuit operation, but it may affect the operating speed of the valve short-circuit protection. Therefore, the simple steady-state incremental testing method cannot fully reflect the characteristics and capabilities of the valve group differential protection, as well as the existing risks, thereby reducing the reliability and safety of the protection device and the protection system.

[0005] In the process of realizing this invention, the inventors of this application discovered that the above-mentioned solutions of the prior art have the drawback of reducing the reliability and safety of the protection device and the protection system. Summary of the Invention

[0006] The purpose of this invention is to provide a differential protection test method and system for converter variable valve groups that simulates fault processes. This differential protection test method and system for converter variable valve groups that simulates fault processes has the function of ensuring the reliability and safety of the protection device and the operation of the protection system.

[0007] To achieve the above objectives, embodiments of the present invention provide a differential protection test method for a converter valve group simulating a fault process, comprising:

[0008] Parameters are configured through human-computer interaction;

[0009] Acquire the status data of the DC protection device during normal operation;

[0010] Set multiple fault modes to obtain fault data corresponding to each of the fault modes;

[0011] The fault data is discretized to obtain AC side discrete data and DC side discrete data;

[0012] Drive the synchronous transmission of the AC-side discrete data and the DC-side discrete data;

[0013] Fault simulation tests are performed based on the discrete data from the AC side and the discrete data from the DC side.

[0014] Optionally, the parameter configuration includes system parameters and fault parameters. The system parameters include DC rated voltage, smoothing reactor inductance, and system equivalent impedance. The fault parameters include fault loop resistance, fault loop inductance, fault time, converter valve lockout drop time, and external fault adjustment coefficient.

[0015] Optionally, acquiring the status data of the DC protection device during normal operation includes:

[0016] Set the DC protection device to operate under load;

[0017] The three-phase AC current i of the DC protection device under load is obtained according to formula (1). a (t)=I m *sin(2πft+φ),φ=0,-2 / 3π,2 / 3π, (1)

[0018] Among them, i a (t) represents the three-phase alternating current, I mHere, f is the peak value of the primary load current, t is the time, and φ is the phase.

[0019] The DC side current of the DC protection device under load is obtained according to formula (2).

[0020] i d (t)=I m (2)

[0021] Among them, i d (t) represents the DC-side current.

[0022] Optionally, multiple fault modes can be set to obtain fault data corresponding to the various fault modes, including:

[0023] DC circuit fault in the converter valve;

[0024] The DC-side current during a DC line fault is obtained according to formula (3).

[0025] i d (t)=I m +(I g -I m )(1-e t / τ (3)

[0026] Where τ is the time constant of the first-order step response, I g This represents the peak value of the fault current.

[0027] The three-phase AC current during a DC line fault is obtained according to formula (4).

[0028] i a (t)=I m +(I g -I m )(1-e t / τ )*sin(2πft+φ+α), φ=0, -2 / 3π, 2 / 3π, (4)

[0029] Where α is the real-time phase of the A-phase current at the time of the fault.

[0030] Optionally, setting multiple fault modes to obtain fault data corresponding to multiple fault modes further includes:

[0031] Set up a converter valve lockout fault;

[0032] The DC-side current during a converter valve lock-up fault is obtained according to formula (5).

[0033] i d (t)=I g (5) ′(1-t / T), 0<t<T

[0034] Among them, I g ′ represents the DC current at the time of blocking, and T is the configured value;

[0035] The three-phase AC current during a converter valve lockout fault can be obtained using formula (6).

[0036] i a (t)=I g ′(1-t / T))*sin(2πft+φ+β);φ=0,-2 / 3π,2 / 3π,0 <t<T, (6)

[0037] Wherein, β is the real-time phase of the A-phase current at the moment the converter valve is locked.

[0038] Optionally, setting multiple fault modes to obtain fault data corresponding to multiple fault modes further includes:

[0039] Faults within the zone of the converter valve;

[0040] The three-phase AC current during a fault in the converter valve zone is obtained according to formula (4);

[0041] When a fault occurs within the converter valve zone, the DC side current is zero.

[0042] Optionally, driving the synchronous transmission of the AC-side discrete data and the DC-side discrete data includes:

[0043] First, the discrete data from the AC side is sent;

[0044] After waiting for a preset delay time, the DC-side discrete data is sent.

[0045] Optionally, fault simulation testing based on the AC-side discrete data and the DC-side discrete data includes:

[0046] The discrete data of the DC protection device under load is sent to the test host.

[0047] Discrete data of DC line faults in the converter valve are sent to the test host.

[0048] Obtain the lockout command of the DC protection device;

[0049] Determine whether the control system has received the lockout command from the DC protection device;

[0050] If the control system receives a lockout command from the DC protection device, it will send discrete data of the converter valve lockout fault to the test host.

[0051] The operating characteristics of the DC protection device under different DC electronic instrument transformer delays were tested.

[0052] Adjust the output coefficient of the digital quantity of the DC electronic instrument transformer to make the output waveform of different DC electronic instrument transformers consistent;

[0053] The sensitivity of obtaining faults outside the differential protection zone of the valve group.

[0054] Optionally, the fault simulation test based on the AC-side discrete data and the DC-side discrete data further includes:

[0055] The discrete data of the fault within the area is sent to the test host;

[0056] The differential action time of the valve group is obtained based on the interlocking and tripping commands of the DC protection device.

[0057] Adjust the system parameters and the fault parameters;

[0058] Test the sensitivity of the differential protection zone of the valve group for faults within the zone.

[0059] On the other hand, the present invention also provides a differential protection test system for simulating fault processes in a converter valve group, characterized in that it includes:

[0060] The host computer is used for human-computer interaction and the generation of test data.

[0061] The lower-level machine is connected to the upper-level machine and is used to discretize the test data and perform time control according to the AC / DC output characteristics to complete the non-phase synchronous output;

[0062] A controller for performing differential protection test methods as described above.

[0063] Through the above technical solution, the differential protection test method for converter valve group with fault process simulation provided by the present invention acquires data during normal operation of DC protection device and fault data under various fault modes, discretizes these data, and finally sends the AC side discrete data and DC side discrete data to DC protection device simultaneously to perform differential protection characteristic tests in sequence. This enables the differential protection characteristics of valve group to be tested, ensuring that DC protection device can operate more reliably and improving the safety of protection system.

[0064] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0065] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0066] Figure 1 This is a flowchart of a differential protection test method for a converter valve group simulating a fault process according to an embodiment of the present invention;

[0067] Figure 2 This is a flowchart of a differential protection test method for a converter transformer valve group simulating a fault process according to an embodiment of the present invention, which obtains the status data of DC protection during normal operation;

[0068] Figure 3 This is a flowchart of a differential protection test method for a converter valve group simulating a fault process according to an embodiment of the present invention, which is used to obtain fault data.

[0069] Figure 4 This is a flowchart of a fault simulation method for a differential protection test method of a converter valve group according to an embodiment of the present invention.

[0070] Figure 5 A block diagram of a differential protection test system for a converter variable valve group simulating a fault process according to an embodiment of the present invention. Detailed Implementation

[0071] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0072] Figure 1 This is a flowchart of a differential protection test method for a converter valve group based on a fault process simulation according to an embodiment of the present invention. Figure 1 The differential protection test method may include:

[0073] In step S10, parameter configuration is performed through human-computer interaction. This parameter configuration involves interaction with the host computer, using a user-friendly interface and C language programming. The parameter configuration includes system parameters and fault parameters, which are used as configuration parameters to reduce the workload of on-site testing personnel, allowing for testing without the need for system calculations and analysis.

[0074] In step S11, the state data of the DC protection device during normal operation is obtained. In order to ensure the normal operation of the DC protection device at the beginning of the fault simulation test, that is, to establish the working environment before the test, it is necessary to generate the state data of the DC protection device during normal operation, that is, steady-state data.

[0075] In step S12, multiple fault modes are set to obtain fault data corresponding to each mode. Specifically, to test the operating characteristics of the differential protection of the converter valve, multiple fault modes need to be set, and fault data under these modes needs to be obtained to facilitate accurate fault simulation later.

[0076] In step S13, the fault data is discretized to obtain AC-side discrete data and DC-side discrete data. Specifically, the host computer transmits the fault data to the test host (lower-level computer), which then discretizes the fault data to generate AC-side discrete data and DC-side discrete data. The AC-side discrete data includes normal operation discrete data and fault discrete data, and the DC-side discrete data also includes normal operation discrete data and fault discrete data.

[0077] In step S14, the AC-side discrete data and DC-side discrete data are transmitted synchronously. The AC-side discrete data is controlled by the FPGA chip and sent to the D / A chip in real time according to the sampling rate of the D / A chip. The DC-side discrete data is simulated and encoded according to the sampling rate and sampling protocol of the DC electronic instrument transformer. Specifically, after discretization, a complete sequence of sampled values ​​is formed, and real-time feedback calculation is performed for state switching, ensuring that the test data is uninterrupted. This facilitates subsequent processing of the DC electronic instrument transformer output as a continuous waveform, eliminating the need for secondary interpolation during message transmission.

[0078] In step S15, a fault simulation test is performed based on the AC-side discrete data and the DC-side discrete data. Specifically, sending the AC-side discrete data and the DC-side discrete data to the test host allows for the testing of the differential protection of the valve group.

[0079] In steps S10 to S15, human-machine interaction is first performed via a host computer to configure parameters. After configuration, data from the normal operation of the DC protection device and fault data under various fault conditions are acquired. This data is then discretized and simultaneously sent to the test host to test the differential protection of the converter transformer valve group in the DC protection device.

[0080] Traditional differential calculations for valve short-circuit protection typically employ steady-state incremental testing methods. However, this method cannot fully reflect the characteristics and capabilities of valve group differential protection, as well as the risks involved, thus reducing the reliability and safety of the protection device and system. Furthermore, related testing technologies include integrated digital-analog relay protection testers, RTDS or PSCAD dynamic simulation testing, and static testing of UHVDC protection. Specifically, integrated digital-analog relay protection testers apply AC signals to test the integrated digital-analog relay protection device. Since AC signals have phase information, phase adjustment is generally used to synchronize digital and analog quantities during the sampling time. However, the signal output by a DC electronic current transformer does not contain phase information, so phase adjustment cannot achieve digital-analog synchronization. RTDS or PSCAD dynamic simulation testing requires a large amount of auxiliary equipment and occupies a very large area, therefore it can only be conducted in a laboratory. Furthermore, it requires an integrated test setup of the control system and DC protection system, making it impossible to test the DC protection device separately. The entire testing process is extremely costly and cannot be carried out on-site. Static testing of UHVDC protection typically involves applying static test parameters to the DC protection device to induce its operation and test the overall characteristics and logic relationships. However, this method cannot capture the impact of fault processes or the time delay between digital and analog signals on the DC protection. Furthermore, it cannot test the operating characteristics of valve group differential protection. In this embodiment of the invention, a method that simultaneously transmits discrete data from the AC side and the DC side to the DC protection device effectively tests the differential protection characteristics of the valve group with high measurement accuracy. This ensures more reliable operation of the DC protection device and improves the safety of the protection system.

[0081] In this embodiment of the invention, the specific contents of the system parameters include the DC rated voltage, the smoothing reactor inductance, and the system equivalent impedance.

[0082] In this embodiment of the invention, the specific contents of the fault parameters include fault loop resistance, fault loop inductance, fault time, converter valve lock-up drop time, and external fault adjustment coefficient.

[0083] In this embodiment of the invention, in order to obtain the status data of the DC protection during normal operation, it is also necessary to put the UHVDC protection into a load-bearing operation state. The specific steps are as follows: Figure 2 As shown. Specifically, in Figure 2 The differential protection test method may include:

[0084] In step S20, the DC protection device is set to operate under load. To achieve this, the corresponding parameter configuration parameters need to be adjusted. Specifically, when testing the main unit, the AC current on the valve side (D side) is selected as the test point, and three-phase AC current is applied to the test point, while DC current is applied to the high and low ends of the converter.

[0085] In step S21, the three-phase AC current of the DC protection device under load is obtained according to formula (1).

[0086] i a (t)=I m *sin(2πft+φ),φ=0,-2 / 3π,2 / 3π, (1)

[0087] Among them, i a (t) represents the three-phase alternating current, I m Let f be the peak value of the load current, t be the time, and φ be the phase.

[0088] In step S22, the DC side current of the DC protection device under load is obtained according to formula (2).

[0089] i d (t)=I m (2)

[0090] Among them, i d (t) represents the DC side current.

[0091] In steps S20 to S22, the UHVDC protection is first put into a load-bearing operation state. The three-phase AC current and DC side current at this time are acquired and used as the status data of the DC protection device during normal operation. At the same time, the status data of the control system during normal operation is generated to unlock the DC protection and put the DC protection device into the working state.

[0092] In this embodiment of the invention, in order to obtain AC-side fault data and DC-side fault data under various fault modes, it is also necessary to design various faults and obtain the corresponding fault data. Specific steps can be as follows: Figure 3 As shown. Specifically, in Figure 3 The differential protection test method may include:

[0093] In step S30, a DC line fault is set for the converter valve. Specifically, by adjusting parameter configurations, the DC protection is designed to lock the converter valve after a DC line fault, and then restart the DC system. This verifies the characteristics of the valve differential protection in the event of a fault outside the converter valve zone, and generates fault data based on the time of the fault occurrence.

[0094] In step S31, the DC side current during a DC line fault is obtained according to formula (3).

[0095] i d (t)=I m +(I g -I m )(1-e t / τ (3)

[0096] Where τ is the first-order step response time constant, and τ=L / R, L is the fault loop inductance, R is the fault loop resistance, and I g This represents the peak value of the fault current. Specifically, the DC-side current exhibits a first-order step response characteristic.

[0097] In step S32, the three-phase AC current during a DC line fault is obtained according to formula (4).

[0098] i a (t)=I m +(I g -I m )(1-e t / τ )*sin(2πft+φ+α), φ=0, -2 / 3π, 2 / 3π, (4)

[0099] Where α is the real-time phase of the A-phase current at the moment of the fault. Specifically, at this time, the converter valve is still operating normally, the load current is rising rapidly, and the AC side exhibits three-phase modulation characteristics, with the current rise time constant consistent with the DC step response.

[0100] In step S33, a converter valve lockout fault is set. This can be achieved by configuring parameters to set the converter valve lockout fault.

[0101] In step S34, the DC side current during a converter valve lock-up fault is obtained according to formula (5).

[0102] i d (t)=I g (5) ′(1-t / T), 0<t<T

[0103] Among them, I g ′ represents the DC current at the time of lockout, and T is the configured value. Specifically, after a fault occurs, the overcurrent protection of the converter valve will activate and lock out the converter valve (adjustment first, then stop the output trigger pulse). After the valve is locked out, the DC current exhibits oscillating decay characteristics. Since the characteristics of the converter valve are difficult to be consistent, the converter valve in the discharge process can be simplified to a linear model.

[0104] In step S35, the three-phase AC current during a converter valve lockout fault is obtained according to formula (6).

[0105] ia (t)=I g ′(1-t / T))*sin(2πft+φ+β);φ=0,-2 / 3π,2 / 3π,0 <t<T, (6)

[0106] Where β is the real-time phase of the A-phase current at the moment the converter valve is locked. Specifically, the AC side current also enters the modulation mode and is modulated according to the DC modulation time.

[0107] In step S36, an intra-zone fault is set for the converter valve. This intra-zone fault can be set by configuring parameters.

[0108] In step S37, the three-phase AC current during the fault in the converter valve zone is obtained according to formula (4).

[0109] In step S38, when a fault occurs within the converter valve zone, the DC-side current is zero. Specifically, the DC-side output current exhibits a step response, rapidly decreasing to zero.

[0110] In steps S30 to S38, faults outside and inside the converter valve zone are sequentially set. Specifically, faults outside the zone include DC line faults and converter valve lockout faults. The corresponding AC and DC currents for these faults are then calculated, resulting in AC and DC fault data, respectively. These AC and DC fault data are then input into the test host to simulate these faults.

[0111] In this embodiment of the invention, for the synchronous transmission of discrete data on the AC side and discrete data on the DC side, the discrete data on the AC side can be transmitted first, and then the discrete data on the DC side can be transmitted after a preset delay time. Specifically, the AC side is an analog output with virtually no delay, while the DC side is a digital output from an electronic current transformer, so there is an inherent output delay. In order to achieve synchronization between the digital and analog quantities of AC and DC (i.e., the discrete data on the DC side and AC side), since the DC side current has no phase, phase interpolation cannot be used to achieve digital-analog synchronization. Therefore, absolute delay synchronization can only be achieved by using an FPGA with a waiting delay. The FPGA uses a 50MHz crystal oscillator period and a 20ns clock cycle to transmit the discrete data on the AC side and DC side independently. The AC side analog transmission is counted as 0 and sent to the D / A chip in real time, and then the analog current value is output by the power amplifier. Each digital channel on the DC side has an independent delay time t. yn Taking the FPGA clock cycle as one wait cycle, the number of transmit wait times for each port is N = t. ynThe message is sent from the hardware and software ports of the simulated DC electronic instrument transformer after a clock cycle of 20. Specifically, an absolute delay synchronous transmission method is used to solve the delay problem of synchronous transmission in the simulation of multiple DC electronic instrument transformers, as well as the problem that traditional digital-analog integrated transmission relies on phase adjustment, while DC current does not contain phase information.

[0112] In this embodiment of the invention, in order to test the characteristics of the valve group differential protection, the above-mentioned AC side discrete data and DC side discrete data need to be sequentially input into the test host. The specific steps are as follows: Figure 4 As shown. Specifically, in Figure 4 The differential protection test method may include:

[0113] In step S40, discrete data of the DC protection device operating under load is sent to the test host. Sending discrete data indicating normal operation ensures that the DC protection device simulated by the test host is initialized to a normal operating state.

[0114] In step S41, discrete data of the DC line fault of the converter valve is sent to the test host. Specifically, during testing, an external fault test is performed first, and the discrete data corresponding to the DC line fault is sent to the test host for testing.

[0115] In step S42, the lockout command of the DC protection device is obtained.

[0116] In step S43, it is determined whether the control system has received a lockout command from the DC protection device.

[0117] In step S44, if the control system receives a lockout command from the DC protection device, the discrete data of the converter valve lockout fault is sent to the test host. Specifically, if the control system receives a lockout command from the DC protection device, it indicates that the DC protection device has activated and needs to switch to a lockout fault-tolerant operating state, meaning the discrete data of the converter valve lockout fault is sent to the test host. In particular, a closed-loop approach is used to simulate the changes in AC and DC current during the valve lockout process by receiving the lockout command from the DC protection device for valve overcurrent, thus completing a real fault scenario simulation test of the random lockout moment of the converter transformer valve group differential protection.

[0118] In step S45, the operating characteristics of the DC protection device under different DC electronic instrument transformer delays are tested. Specifically, the sampling rate, output protocol, and output delay of multiple electronic instrument transformers are simulated to test the adaptability of DC electronic instrument transformers from different manufacturers in valve group differential protection.

[0119] In step S46, the output coefficient of the digital quantity of the DC electronic instrument transformer is adjusted to make the output waveform of different DC electronic instrument transformers consistent. Specifically, by adjusting the digital output coefficient, the differential current regulation of the converter transformer valve group differential protection is completed without changing the waveform characteristics, thus achieving the sensitivity test of the valve group differential operation under fault conditions.

[0120] In step S47, the sensitivity of faults outside the valve group differential protection zone is obtained.

[0121] In step S48, discrete data of faults within the zone are sent to the test host. Specifically, faults within the zone are tested only after tests on faults outside the zone are completed.

[0122] In step S49, the differential action time of the valve group is obtained according to the lockout and trip command of the DC protection device.

[0123] In step S50, the system parameters and fault parameters are adjusted.

[0124] In step S51, the sensitivity of the differential protection of the valve group within the zone for faults is tested.

[0125] In steps S40 to S51, external fault simulation and internal fault simulation are sequentially input into the test host to obtain the sensitivity of the valve group after external fault and internal fault. This sensitivity reflects the operating characteristics of the valve group differential protection. Based on these operating characteristics, the characteristics and capabilities of the differential protection of the protection device can be obtained, thereby improving the reliability and safety of the protection device and the protection system.

[0126] On the other hand, the present invention also provides a differential protection test system (test instrument) for simulating fault processes in converter valve groups, such as... Figure 5 As shown. Specifically, in Figure 5 In this system, the host computer and the slave computer controller can be included.

[0127] The host computer is used for human-machine interaction and test data generation, while the controller is used to execute any of the differential protection test methods mentioned above. The slave computer communicates with the host computer, discretizing the test data and performing time control according to the AC / DC output characteristics to achieve non-phase synchronous output. At the same time, the simulation control system communicates with the protection device, providing the control data required for the UHVDC valve protection to operate, and then receives the operation information from the UHVDC valve protection to change the fault current output.

[0128] Through the above technical solution, the differential protection test method for converter valve group with fault process simulation provided by the present invention acquires data during normal operation of DC protection device and fault data under various fault modes, discretizes these data, and finally sends the AC side discrete data and DC side discrete data to the test host in sequence to perform differential protection characteristic tests. In this way, the differential protection characteristics of valve group can be tested to ensure that DC protection device can operate more reliably and improve the safety of protection system.

[0129] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied 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.

[0130] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0131] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0132] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0133] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0134] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0135] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0136] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0137] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method of testing differential protection of a converter transformer valve group for fault process simulation, characterized in that, include: Parameters are configured through human-computer interaction; Acquire the status data of the DC protection device during normal operation; Set multiple fault modes to obtain fault data corresponding to each of the fault modes; The fault data is discretized to obtain AC side discrete data and DC side discrete data; Drive the synchronous transmission of the AC-side discrete data and the DC-side discrete data; Fault simulation tests were performed based on the AC side discrete data and the DC side discrete data. The parameter configuration includes system parameters and fault parameters. The system parameters include DC rated voltage, smoothing reactor inductance, and system equivalent impedance. The fault parameters include fault loop resistance, fault loop inductance, fault time, converter valve lock-up drop time, and external fault adjustment coefficient. The fault data includes both external and internal faults of the converter valve, wherein the external faults include DC line faults and converter valve lock-up faults. Setting multiple fault modes to obtain fault data corresponding to each fault mode includes: Set up a converter valve lockout fault; The DC side current during a converter valve lock-up fault is obtained according to formula (5). ，（5） in, This represents the DC current at the time of blocking. This is a configuration value; The three-phase AC current during a converter valve lockout fault is obtained according to formula (6). ，（6） in, The real-time phase of the A-phase current at the moment the converter valve is locked; A DC circuit fault was detected in the converter valve. The DC-side current during a DC line fault is obtained according to formula (3). ，（3） in, The time constant of the first-order step response. This represents the peak value of the fault current. The three-phase AC current during a DC line fault is obtained according to formula (4). ，（4） in, The real-time phase of phase A current at the moment of the fault; Faults within the zone of the converter valve; The three-phase AC current during a fault in the converter valve zone is obtained according to formula (4); When a fault occurs within the converter valve zone, the DC side current is zero. The fault simulation test based on the AC side discrete data and the DC side discrete data includes: Send discrete data of faults within the zone to the test host; The differential action time of the valve group is obtained based on the interlocking and tripping commands of the DC protection device. Adjust the system parameters and the fault parameters; Test the sensitivity of the differential protection of the valve group for faults within the zone.

2. The differential protection test method according to claim 1, characterized in that, The status data obtained when the DC protection device is operating normally includes: Set the DC protection device to operate under load; The three-phase AC current of the DC protection device under load is obtained according to formula (1). ，（1） in, The three-phase alternating current, This is the peak value of the primary load current. For frequency, For a moment, For phase; The DC side current of the DC protection device under load is obtained according to formula (2). ，（2） in, This refers to the DC-side current.

3. The differential protection test method according to claim 1, characterized in that, Driving the synchronous transmission of the AC-side discrete data and the DC-side discrete data includes: First, the discrete data from the AC side is sent; After waiting for a preset delay time, the DC-side discrete data is sent.

4. The differential protection test method according to claim 1, characterized in that, The fault simulation test based on the AC side discrete data and the DC side discrete data also includes: The discrete data of the DC protection device under load is sent to the test host. Discrete data of DC line faults in the converter valve are sent to the test host. Obtain the lockout command of the DC protection device; Determine whether the control system has received the lockout command from the DC protection device; If the control system receives a lockout command from the DC protection device, it will send discrete data of the converter valve lockout fault to the test host. The operating characteristics of the DC protection device under different DC electronic instrument transformer delays were tested. Adjust the output coefficient of the digital quantity of the DC electronic instrument transformer to make the output waveform of different DC electronic instrument transformers consistent; Sensitivity to faults outside the differential protection zone of the valve group.

5. A differential protection test system for a converter valve group simulating a fault process, characterized in that, include: The host computer is used for human-computer interaction and the generation of test data. The lower-level machine is connected to the upper-level machine and is used to discretize the test data and perform time control according to the AC / DC output characteristics to complete the non-phase synchronous output; A controller for performing the differential protection test method as described in any one of claims 1 to 4.

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