New energy station sending-out line protection method and system based on current model identification

Abstract

The invention discloses a new energy station sending-out line protection method and system based on current model identification. A fault component network is adopted to avoid the influence of the system operation state. Errors caused by a line distributed capacitance model can be eliminated by constructing a mathematical model based on a Bergeron model. Multi-frequency quantity information in a transient process can be effectively extracted by using a matrix pencil algorithm; setting calculation can be simplified by calculating system model parameters through power frequency quantity information, and meanwhile the protection method can adapt to various types of power sources; and the model error is calculated by using the non-power-frequency transient quantity, so that the rapid action of protection can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of control and protection of new energy power generation systems, and specifically relates to a new energy station transmission line protection method and system based on current model identification. Background Art

[0002] The emergence of new power systems, primarily based on renewable energy, has promoted the widespread application of power electronics. Unlike synchronous generators, power electronic power supplies are less tolerant to overcurrent and overvoltage. Their weak support and low noise immunity lead to greater uncertainty in fault response. The integration of a large number of power electronic devices has profoundly altered the fault characteristics of these new power systems, overturning the traditional theoretical basis for relay protection based on the characteristics of synchronous generators.

[0003] Relay protection is the first line of defense for the safe operation of power systems. Transmission lines are the electrical components with the highest failure rates in power systems. To ensure the rapid and reliable removal of line faults, comprehensive line protection devices are essential. Longitudinal protection, which utilizes electrical quantities at both ends, offers advantages such as high sensitivity and inherent phase selection, and is widely used as the primary protection for transmission lines. However, the diverse control strategies of converters for renewable energy power sources complicate the operating parameters and power characteristics of converter-type power sources, making protection difficult to set. Furthermore, the flexible and ever-changing power system network topology complicates protection coordination. Consequently, new power systems present challenges for setting and coordinating protection.

[0004] Traditional line protection in new energy station transmission systems will face challenges such as increased speed requirements, changes in power supply fault characteristics, and difficulties in setting and coordination. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a new energy station transmission line protection method and system based on current model identification, which is used to solve the technical problems faced by the new energy station transmission line protection in terms of speed, power supply characteristics and setting coordination.

[0006] The present invention adopts the following technical solutions: A first aspect of the present invention provides a method for protecting a new energy station transmission line based on current model identification, comprising the following steps: S1. Collect the current of each phase on the new energy side and each phase current on the grid side ; S2, for each phase current and each phase current Perform zero sequence compensation to obtain the current after compensation and ; S3, the current after compensation and Subtract the current of the previous cycle to get the fault component current and ; S4. For each phase current, use the matrix bundle algorithm to extract the fault component current and Complex amplitude at each characteristic frequency and , Extracted by the matrix bundle algorithm N characteristic frequencies; S5. According to the complex amplitude at each characteristic frequency and Computation and Streaming Hechaliu ; S6. Find the characteristic frequency closest to the power frequency , according to the characteristic frequency Down and flow Hechaliu Calculate the equivalent inductance of the new energy station on the new energy side and the equivalent inductance of the grid at the grid side ; S7, according to the equivalent inductance and Calculate the eigenfrequency The theoretical and differential current ratios at other characteristic frequencies except and ; S8. Search The characteristic frequencies corresponding to the attenuated DC component and the two highest harmonic components with the lowest frequency generate a set Ω, and then according to the characteristic frequencies , The flow Hechaliu and the ratio of theoretical and differential currents and Calculating the error function and ; S9, according to the error function and Action threshold The relationship between the fault location and the action threshold is determined It is determined based on the maximum unbalance of the error function when a fault outside the phase zone occurs.

[0007] Preferably, the compensated current The calculation formula is as follows:

[0008] in, For protection device m The measured zero sequence current, , is the zero-sequence inductance per unit length of the line, is the positive sequence inductance per unit length of the line.

[0009] Preferably, in step S8, the characteristic frequency used The characteristic frequency components include the attenuated DC component and the two highest harmonic components with the lowest frequency.

[0010] Preferably, the sum flow at each characteristic frequency Hechaliu The calculation formula is as follows: .

[0011] Preferably, the theoretical and differential current ratios at each characteristic frequency are and The calculation is as follows:

[0012] in, is the line wave impedance; is the hyperbolic sine function; is the hyperbolic cosine function; γ is the line propagation coefficient, d is the line length.

[0013] Preferably, if or , it is judged as a fault outside the phase area, and the line protection will not be activated; and , if it is judged as a fault in the phase area, the line protection will be activated.

[0014] Preferably, the error function and The calculation formula is as follows:

[0015] in, is the characteristic frequency Down and flow, and is the characteristic frequency The complex amplitude of the lower fault component current; and is the characteristic frequency The theoretical and differential current ratio under .

[0016] A second aspect of the present invention provides a new energy station transmission line protection system based on current model identification, comprising: Acquisition module, using the new energy side protection device of the new energy transmission line m and grid-side protection devices n The current sensor collects the current on both sides and , perform zero-sequence compensation on each phase current to obtain the compensated current and ; The extraction module subtracts the current of the previous cycle from the compensated current to obtain the fault component current and For each phase current, a matrix bundle algorithm is used to extract the complex amplitude of the fault component current at each characteristic frequency. and , Extracted by the matrix bundle algorithm N characteristic frequencies; The first calculation module calculates the sum flow at each characteristic frequency Hechaliu ; The second calculation module is to find the characteristic frequency closest to the power frequency , according to the characteristic frequency Down and flow Hechaliu Calculate the equivalent inductance of the new energy station on the new energy side and the equivalent inductance of the grid at the grid side ; According to the equivalent inductance and Calculate the eigenfrequency The theoretical and differential current ratios at other characteristic frequencies except and ; The judgment module looks for the characteristic frequency generation set Ω corresponding to the attenuated DC component and the two highest harmonic components with the lowest frequency, and calculates the error function and ; According to the error function and Action threshold The relationship between the fault location and the action threshold is determined It is determined based on the maximum unbalance of the model error (error function) when a fault outside the phase zone occurs.

[0017] In a third aspect, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above-mentioned method for protecting transmission lines of new energy stations based on current model identification are implemented.

[0018] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for protecting transmission lines of new energy stations based on current model identification.

[0019] In a fifth aspect, a chip comprises a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above-mentioned method for protecting transmission lines of new energy stations based on current model identification are implemented.

[0020] In a sixth aspect, an embodiment of the present invention provides an electronic device, comprising a computer program, which, when executed by the electronic device, implements the steps of the above-mentioned method for protecting transmission lines of new energy stations based on current model identification.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: A new energy station transmission line protection method based on current model identification uses a matrix bundle algorithm to extract transient current signal characteristics, calculates system model parameters using power frequency quantities, and then calculates model errors based on non-power frequency transient quantities. The fault occurrence interval is determined based on the model errors.

[0022] Furthermore, the protection principle extracts transient current signal characteristics through a matrix bundle algorithm, which can utilize the abundant non-power frequency harmonic signals in the transient process and operate faster.

[0023] Furthermore, the protection principle performs model identification based on the fault component network and line distributed parameter model, eliminating the error caused by the line distributed capacitance and is not affected by the system operating status.

[0024] Furthermore, the system model parameters are calculated using power frequency information, which simplifies the setting calculation and makes the protection scheme applicable to various types of power systems.

[0025] It can be understood that the beneficial effects of the second to sixth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0026] In summary, the use of a fault component network can mitigate the impact of system operating conditions; constructing a mathematical model based on the Berelon model eliminates errors introduced by the line distributed capacitance model. The matrix bundle algorithm effectively extracts multi-frequency information from transient processes; calculating system model parameters using power frequency information simplifies setting calculations and makes the proposed protection method adaptable to a variety of power sources; and calculating model errors using non-power frequency transient quantities enables rapid protection action.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 This is a flow chart of a low-frequency transmission line protection method based on time-domain model identification; Figure 2 Schematic diagram of the simulation model of the present invention; Figure 3 This is a schematic diagram of the wind farm transmission line model of the present invention; Figure 4 is a schematic diagram of the three-phase fault simulation results, where (a) is f 1 fault, (b) is f 2 faults, (c) is f 3 faults, (d) is f 4 faults, (e) is f 5. Fault; Figure 5 is a schematic diagram of the simulation results of a single-phase grounding fault, where (a) is f 1 fault, (b) is f 2 faults, (c) is f 3 faults, (d) is f 4 faults, (e) is f 5. Fault; Figure 6 A schematic diagram of a computer device provided in accordance with an embodiment of the present invention; Figure 7 The present invention is a block diagram of an electronic device according to an embodiment of the present invention.

[0030] Among them, 60. Computer device; 61. Processor; 62. Memory; 63. Computer program; 600. Electronic device; 610. Processing unit; 620. Storage unit; 6201. Random access memory unit; 6202. Cache memory unit; 6203. Read-only memory unit; 6204. Program / Utility; 6205. Program module; 630. Bus; 640. Display unit; 650. Input / output interface; 660. Network adapter; 700. External device. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0033] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0034] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0035] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0036] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0037] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0038] The present invention provides a new energy station transmission line protection method based on current model identification. According to the fault component network and the Berelon model, a mathematical model of the ratio of the sum and difference of the fault component currents at both ends when an out-of-zone fault occurs is established, and a model error calculation function is constructed as a protection criterion; the frequency and complex amplitude information of the current are extracted using the least squares matrix bundle algorithm, the system model parameters are calculated using the power frequency quantity information, the non-power frequency transient quantity is substituted into the model error calculation formula, the model error is calculated, and the fault occurrence interval is judged based on this.

[0039] The use of a fault component network mitigates the impact of system operating conditions; constructing a mathematical model based on the Berelon model eliminates errors introduced by the line distributed capacitance model. A matrix bundle algorithm effectively extracts multi-frequency information from transient processes; calculating system model parameters using power-frequency information simplifies setting calculations and makes the proposed protection method adaptable to a variety of power sources. Calculating model errors using non-power-frequency transients enables rapid protection action.

[0040] Example 1 See also Figure 1 The present invention provides a new energy station transmission line protection method based on current model identification. The method calculates system model parameters based on power frequency quantities, calculates model errors based on non-power frequency quantities, and determines the fault occurrence interval based on the model errors to implement line protection. The specific steps are: Step 1: Use the new energy side protection device of the new energy transmission line m and grid-side protection devices n The current sensor collects the current on both sides and ( ϕ = A,B,C, indicating A, B, and C phases).

[0041] Step 2: Perform zero-sequence compensation on each phase current to obtain the compensated current and ,by For example, Similarly, the calculation method is as follows: (1) in For protection devicem The measured zero sequence current, , 、 is the zero-sequence and positive-sequence inductance per unit length of the line Step 3: Subtract the current of the cycle before the fault from the compensated current to obtain the fault component current and

[0042] Step 4: For each phase current, use the matrix bundle algorithm to extract the complex amplitude of the fault component current at each characteristic frequency and , Extracted by the matrix bundle algorithm N A characteristic frequency.

[0043] Step 5: Calculate the Hechaliu The calculation formula is as follows: (2) Step 6: Find the characteristic frequency closest to the power frequency , calculate the system model (new energy station model and grid equivalent model) parameters (i.e. the equivalent inductance of the new energy station and grid at the installation locations of the protection devices on both sides) based on the power frequency information and , the calculation formula is as follows: (3) in , γ is the line propagation coefficient, d is the line length.

[0044] Step 7: Calculate the ratio of theoretical and differential current at each characteristic frequency and , the calculation formula is as follows: (4) Step 8: Find the characteristic frequency generation set Ω corresponding to the attenuated DC component and the two lowest-frequency high-order harmonic components, and calculate the error function and , the calculation formula is as follows: (5) Step 9: Determine the fault location based on the following criteria: or , it is judged as a fault outside the phase area, and the protection does not operate; and , it is judged as a fault in the phase area, and the protection is activated; is the action threshold, which is determined according to the maximum unbalance of the model error (error function) when a fault outside the phase zone occurs.

[0045] Those skilled in the art will appreciate that various aspects of the present invention may be implemented as systems, methods, or program products. Accordingly, various aspects of the present invention may be implemented in the following forms: entirely in hardware, entirely in software (including firmware, microcode, etc.), or in a combination of hardware and software, collectively referred to herein as "circuits," "modules," or "platforms."

[0046] Example 2 The present invention provides a new energy station transmission line protection system based on current model identification. The system can be used to implement the above-mentioned new energy station transmission line protection method based on current model identification. Specifically, the new energy station transmission line protection system based on current model identification includes an acquisition module, an extraction module, a first calculation module, a second calculation module and a judgment module.

[0047] Among them, the acquisition module uses the new energy side protection device of the new energy transmission line m and grid-side protection devices n The current sensor collects the current on both sides and , perform zero-sequence compensation on each phase current to obtain the compensated current and ; The extraction module subtracts the current of the previous cycle before the fault from the compensated current to obtain the fault component current and , for one phase current, run the matrix bundle program to extract the complex amplitude of the fault component current at each characteristic frequency and , Extracted by the matrix bundle algorithm N characteristic frequencies; The first calculation module calculates the sum flow at each characteristic frequency Hechaliu ; The second calculation module is to find the characteristic frequency closest to the power frequency , calculate the system model parameters based on the power frequency information and ; Calculate the theoretical and differential current ratios at each characteristic frequency and ; The judgment module looks for the characteristic frequency generation set Ω corresponding to the attenuated DC component and the two highest harmonic components with the lowest frequency, and calculates the error function and ; According to the error function and Action threshold The fault location is determined by the relationship between the fault location and the maximum unbalanced value of the model error when the fault occurs outside the area.

[0048] Example 3 The present invention provides a terminal 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, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), 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 to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of the new energy station transmission line protection method based on current model identification, including: Utilize the new energy side protection device of the new energy transmission line m and grid-side protection devices n The current sensor collects the current on both sides and ; Perform zero-sequence compensation on each phase current to obtain the compensated current and ; Subtract the current of the previous cycle before the fault from the compensated current to obtain the fault component current and ; For one phase current, run the matrix bundle program to extract the complex amplitude of the fault component current at each characteristic frequency and , Extracted by the matrix bundle algorithm N characteristic frequencies; calculate the sum flow at each characteristic frequency Hechaliu ; Find the characteristic frequency closest to the power frequency , calculate the system model parameters based on the power frequency information and ; Calculate the theoretical and differential current ratios at each characteristic frequency and ; Find the characteristic frequency generation set Ω corresponding to the attenuated DC component and the two highest harmonic components with the lowest frequency, and calculate the error function and ; According to the error function and Action threshold The fault location is determined by the relationship between the fault location and the maximum unbalanced value of the model error when the fault occurs outside the area.

[0049] See also Figure 6 The terminal device is a computer device. The computer device 60 of this embodiment includes: a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61. When the computer program 63 is executed by the processor 61, it implements the method for protecting the transmission line of a new energy station based on current model identification in the embodiment. To avoid repetition, it is not described in detail here. Alternatively, when the computer program 63 is executed by the processor 61, it implements the functions of each model / unit in the protection system for the transmission line of a new energy station based on current model identification in the embodiment. To avoid repetition, it is not described in detail here.

[0050] The computer device 60 may be a desktop computer, a notebook computer, a PDA, a cloud server, or other computing devices. The computer device 60 may include, but is not limited to, a processor 61 and a memory 62. Those skilled in the art will appreciate that Figure 6 This is merely an example of the computer device 60 and does not constitute a limitation of the computer device 60 . The computer device 60 may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the computer device may also include input and output devices, network access devices, buses, etc.

[0051] The processor 61 may be a central processing unit (CPU), or other general-purpose processors, a graphics processing unit (GPU), a tensor processing unit (TPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0052] The memory 62 may be an internal storage unit of the computer device 60, such as a hard disk or memory of the computer device 60. The memory 62 may also be an external storage device of the computer device 60, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the computer device 60.

[0053] Furthermore, the memory 62 may include both an internal storage unit of the computer device 60 and an external storage device. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 may also be used to temporarily store data that has been output or is about to be output.

[0054] See also Figure 7 The terminal device is an electronic device 600, which is implemented as a general-purpose computing device. The components of the electronic device may include, but are not limited to, at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including the storage unit 620 and the processing unit 610), and a display unit 640.

[0055] The storage unit stores program codes, which can be executed by the processing unit 610, so that the processing unit 610 performs the steps according to various exemplary embodiments of the present invention described in the above method section of this specification. For example, the processing unit 610 can perform the following steps: Figure 1 Follow the steps shown in .

[0056] The storage unit 620 may include a readable medium in the form of a volatile storage unit, such as a random access memory unit (RAM) 6201 and / or a cache memory unit 6202 , and may further include a read-only memory unit (ROM) 6203 .

[0057] The storage unit 620 may also include a program / utility 6204 having a set (at least one) of program modules 6205, such program modules 6205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0058] Bus 630 may represent one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0059] The electronic device 600 may also communicate with one or more external devices 700 (e.g., a keyboard, a pointing device, a Bluetooth device, etc.), one or more devices that enable a user to interact with the electronic device 600, and / or any device that enables the electronic device 600 to communicate with one or more other computing devices (e.g., a router, a modem). Such communication may occur via an input / output interface 650. Furthermore, the electronic device 600 may also communicate with one or more networks (e.g., a local area network, a wide area network, and / or a public network, such as the Internet) via a network adapter 660. The network adapter 660 may communicate with other modules of the electronic device 600 via a bus 630. It should be understood that, although not shown in the figures, other hardware and / or software modules may be used in conjunction with the electronic device 600, including but not limited to microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0060] Example 4 The present invention also provides a storage medium, specifically a computer-readable storage medium. The computer-readable storage medium is a memory device in a terminal device, used to store programs and data. It is understood that the computer-readable storage medium herein may include both the built-in storage medium in the terminal device and, of course, the extended storage medium supported by the terminal device. It may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for being loaded and executed by a processor. These instructions may be one or more computer programs (including program code). It should be noted that more specific examples of the computer-readable storage medium herein include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical fiber, a portable compact disk read-only memory, an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0061] Computer-readable storage media also include data signals propagated in baseband or as part of a carrier wave, which carry readable program code. Such propagated data signals can take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable storage medium can also be any readable medium other than a readable storage medium, which can send, propagate, or transmit programs for use by or in conjunction with an instruction execution system, device, or device. The program code contained on the readable storage medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical cable, radio frequency, etc., or any suitable combination of the above.

[0062] The program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, C++, and the like, as well as conventional procedural programming languages such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a stand-alone software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device via any type of network, including a local area network or a wide area network, or may be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0063] The processor may load and execute one or more instructions stored in a computer-readable storage medium to implement corresponding steps of the method for protecting the transmission lines of a new energy station based on current model identification in the above embodiment.

[0064] The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may include, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic units, data processing logic units based on quantum computing, and the like.

[0065] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0066] In order to verify the correctness of the protection method proposed in this invention, a wind farm transmission line simulation model is established in MATLAB / Simulink, as shown in the following figure: Figure 2 As shown, a fault is set on the transmission line of the wind farm. f 1. f 5 are back-side faults on the wind farm side and the system side respectively. f 2. f 4 are the wind farm transmission lines that are affected by terminal faults, f 3 is a fault at the midpoint of the wind farm transmission line.

[0067] The wind farm uses a single-unit direct-drive wind turbine equivalent model, with a single wind turbine capacity of 2 MW and a number of 50 units. The collector voltage level is 35 kV, the equivalent resistance is 0.275 Ω, and the equivalent inductance is 1024 μH. The wind farm main transformer capacity is 100 MW, and the short-circuit voltage is 14%. The wind farm transmission line voltage level is 220 kV, the length is 100 km, and a frequency-variable parameter model is used. Figure 3 As shown; the equivalent inductance on the system side is 0.0633H.

[0068] The fault data sampling frequency is 10kHz, the data window length is 10ms, and it slides within 20ms after the fault occurs; the action threshold Set to 0.3.

[0069] When the fault type is set to three-phase fault, the result is shown in Figure 4. m side, the system is n On the side, the red line is the action threshold. f 1. f 5 o'clock, E m 、 E n The protection does not operate if the value is not greater than the action threshold at the same time; and a fault occurs in the area f 2. f 3. f 4, after 10ms, E m 、 E n Stability is greater than the action threshold, protecting the action.

[0070] When the fault type is set to single-phase grounding fault, the results are shown in Figure 5. The simulation results are very similar to those of three-phase fault. The protection does not operate when the fault occurs outside the zone, but operates reliably when the fault occurs inside the zone.

[0071] In summary, the present invention proposes a method and system for protecting transmission lines at renewable energy stations based on current model identification. This method utilizes transient currents to rapidly, reliably, and sensitively protect transmission lines at renewable energy stations. It is easy to configure and adapt to various types of renewable energy power systems, resolving challenges faced by relay protection for transmission lines at renewable energy stations. Simulation results demonstrate the correctness and reliability of the proposed protection method.

[0072] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0073] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0074] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0075] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical functional division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, and can be electrical, mechanical, or other forms.

[0076] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0077] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0078] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above-mentioned various method embodiments. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0079] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices, 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.

[0080] 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.

[0081] 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 The steps for the function specified in one or more boxes.

[0082] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A new energy station transmission line protection method based on current model identification, characterized in that: The following steps are involved: S1. Collect the current of each phase on the new energy side and each phase current on the grid side ; S2, for each phase current and each phase current Perform zero sequence compensation to obtain the current after compensation and ; S3, the current after compensation and Subtract the current of the previous cycle to get the fault component current and ; S4. For each phase current, use the matrix bundle algorithm to extract the fault component current and Complex amplitude at each characteristic frequency and , are the N eigenfrequencies extracted by the matrix bundle algorithm; S5. According to the complex amplitude at each characteristic frequency and Computation and Streaming Hechaliu ; S6. Find the characteristic frequency closest to the power frequency , according to the characteristic frequency Down and flow Hechaliu Calculate the equivalent inductance of the new energy station on the new energy side and the equivalent inductance of the grid at the grid side ; S7, according to the equivalent inductance and Calculate the eigenfrequency The theoretical and differential current ratios at other characteristic frequencies except and ; S8. Search The characteristic frequencies corresponding to the attenuated DC component and the two highest harmonic components with the lowest frequency generate a set Ω, and then according to the characteristic frequencies , The flow Hechaliu and the ratio of theoretical and differential currents and Calculating the error function and ; S9, according to the error function and Action threshold The relationship between the fault location and the action threshold is determined It is determined based on the maximum unbalance of the error function when a fault outside the phase zone occurs.

2. The new energy station transmission line protection method based on current model identification according to claim 1 is characterized in that: The compensated current The calculation formula is as follows: in, is the zero-sequence current measured by the protection device m, , is the zero-sequence inductance per unit length of the line, is the positive sequence inductance per unit length of the line.

3. The new energy station transmission line protection method based on current model identification according to claim 1 is characterized in that: In step S8, the characteristic frequency used The characteristic frequency components include the attenuated DC component and the two highest harmonic components with the lowest frequency.

4. The new energy station transmission line protection method based on current model identification according to claim 1 is characterized in that: Sum flow at each characteristic frequency Hechaliu The calculation formula is as follows: 。 5. The new energy station transmission line protection method based on current model identification according to claim 1 is characterized in that: Theoretical and differential current ratios at each characteristic frequency and The calculation is as follows: in, is the line wave impedance; is the hyperbolic sine function; is the hyperbolic cosine function; γ is the line propagation coefficient, and d is the line length.

6. The new energy station transmission line protection method based on current model identification according to claim 1 is characterized in that: like or , it is judged as a fault outside the phase area, and the line protection will not be activated; and , if it is judged as a fault in the phase area, the line protection will be activated.

7. The new energy station transmission line protection method based on current model identification according to claim 6 is characterized in that: Error function and The calculation formula is as follows: in, is the characteristic frequency Down and flow, and is the characteristic frequency The complex amplitude of the lower fault component current; and is the characteristic frequency The theoretical and differential current ratio under .

8. A new energy station transmission line protection system based on current model identification, characterized in that: include: The acquisition module uses the current sensors of the new energy side protection device m and the grid side protection device n of the new energy transmission line to collect the current on both sides and , perform zero-sequence compensation on each phase current to obtain the compensated current and ; The extraction module subtracts the current of the previous cycle from the compensated current to obtain the fault component current and For each phase current, a matrix bundle algorithm is used to extract the complex amplitude of the fault component current at each characteristic frequency. and , are the N eigenfrequencies extracted by the matrix bundle algorithm; The first calculation module calculates the sum flow at each characteristic frequency Hechaliu ; The second calculation module is to find the characteristic frequency closest to the power frequency , according to the characteristic frequency Down and flow Hechaliu Calculate the equivalent inductance of the new energy station on the new energy side and the equivalent inductance of the grid at the grid side ; According to the equivalent inductance and Calculate the eigenfrequency The theoretical and differential current ratios at other characteristic frequencies except and ; The judgment module looks for the characteristic frequency generation set Ω corresponding to the attenuated DC component and the two highest harmonic components with the lowest frequency, and calculates the error function and ; According to the error function and Action threshold The relationship between the fault location and the action threshold is determined It is determined based on the maximum unbalance of the error function when a fault outside the phase zone occurs.

9. 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 the method of any one of claims 1 to 7.

10. A computing 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 steps for executing the method according to any one of claims 1 to 7.

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