An energy integral differential protection method and system based on a distributed parameter model

Abstract

The application discloses an energy integral differential protection method and system based on a distribution parameter model, which comprises the following steps: collecting three-phase voltage and three-phase current instantaneous values of a line at a local side and an opposite side in real time; calculating three-phase current calculation values of the local side at the same time based on the three-phase voltage and three-phase current instantaneous values of the opposite side; calculating three-phase current difference currents based on the three-phase current instantaneous values of the local side collected in real time and the three-phase current calculation values of the local side at the same time; calculating three-phase differential current operating quantities based on the three-phase current difference currents; and forming an energy integral differential protection operating criterion by using the three-phase differential current operating quantities, and performing differential protection when the three-phase differential current operating quantities meet the differential protection operating criterion. The application solves the problems of frequency deviation and harmonics of traditional Bergeron phasor differential protection after faults of power electronic devices such as new energy and flexible direct current, and improves the differential protection operating performance in a new energy power transmission scene.

Description

Technical Field

[0001] This invention belongs to the technical field of relay protection, and relates to differential protection technology, and in particular to an energy integral differential protection method and system based on a distributed parameter model. Background Technology

[0002] With the increasing proportion of new energy sources in the power system, the characteristics of the system's power supply are undergoing profound changes. Traditional distance-based and directional protection principles are significantly affected, and in some new energy transmission channels, they have even been forced out of operation. Current differential protection, with its advantages of full-line high-speed operation, absolute selectivity, and immunity to system oscillations, is currently the most important primary protection in the power system. With the further development of new energy sources, long-distance transmission scenarios such as desert and deep-sea wind power are gradually emerging, and the impact of transmission line capacitive current on differential protection is becoming increasingly significant.

[0003] Phasor differential protection based on the Berylon model calculates the differential current using a line distributed parameter model, unaffected by transient and steady-state capacitive currents in the transmission line. However, the sensitivity of the Berylon differential criterion is affected by the unbalanced differential current in the non-faulty phases during a single-phase ground fault within the zone. Furthermore, the protection criterion for phasor differential protection based on the Berylon model requires extraction of power frequency phasors; however, the frequency deviation and harmonic characteristics of fault currents in renewable energy transmission lines often make power frequency phasor extraction based on Fourier algorithms difficult, leading to a decrease in differential protection performance. Therefore, the performance degradation of differential protection in renewable energy transmission lines is specifically manifested in the following ways: when renewable energy is transmitted over long lines, the capacitive current cannot be ignored, affecting the differential protection performance. Traditional Berylon differential protection, in the event of a single-phase ground fault, calculation errors can lead to differential currents in the non-faulty phases, potentially causing maloperation of the protection. Traditional Beryl differential protection uses phasor differential mode. The response characteristics of power electronic equipment such as new energy and flexible DC after AC system faults are highly affected by the control strategy, which may lead to problems such as frequency deviation and harmonics, making it difficult to extract power frequency phasors and affecting the sensitivity and speed of differential protection. Summary of the Invention

[0004] In view of the above-mentioned technical problems existing in the prior art, the present invention proposes an energy integral differential protection method based on a distributed parameter model to improve the differential protection action performance.

[0005] To solve the above-mentioned technical problems, the present invention specifically adopts the following technical solution:

[0006] In a first aspect, the present invention discloses an energy integral differential protection method based on a distributed parameter model, comprising the following steps:

[0007] Step 1: Real-time acquisition of instantaneous values ​​of three-phase voltage and three-phase current on both the local and opposite sides of the line;

[0008] Step 2: Calculate the three-phase current at the same moment on this side based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line;

[0009] Step 3: Based on the real-time acquired instantaneous values ​​of the three-phase current on this side and the calculated values ​​of the three-phase current on this side at the same time, the differential current of the three-phase current is calculated.

[0010] Step 4: Calculate the three-phase differential current action based on the three-phase current differential current;

[0011] Step 5: Use the three-phase differential current action quantity to construct the energy integral differential protection action criterion. When the three-phase differential current action quantity satisfies the differential protection action criterion, the differential protection will operate.

[0012] More preferably,

[0013] In step 1, the instantaneous values ​​of the three-phase voltage and current of the protection device on this side (i.e., side m) are collected at various times, and set as follows: , , , , , Through the signal transmission channel, the instantaneous values ​​of the three-phase voltage and current at the same time on the opposite side of the line, i.e., the nth side, are obtained and denoted as [missing information]. , , , , , .

[0014] More preferably,

[0015] In step 2, the opposite side of the line t Substituting the instantaneous values ​​of voltage and current at time t into the Berylon model equations, the m-side can be calculated. t Calculated value of three-phase current at time , , .

[0016] More preferably,

[0017] In step 3, the three-phase differential current at time t is calculated according to the following formula:

[0018]

[0019] In the formula For the three-phase differential current at time t on side m, The three-phase sampling current at time t on side m is... To calculate the m-side according to the Berylon model t Calculated values ​​of three-phase current at any given time; Values or or , respectively represent , , Three phases.

[0020] More preferably,

[0021] In step 4, the three-phase differential current is calculated according to the following formula:

[0022]

[0023] in For three-phase differential current, Values or or , respectively represent , , Three phases, T It is one cycle time.

[0024] More preferably,

[0025] In step 5, the energy integral differential protection action criterion is as follows:

[0026]

[0027] In the formula: For fixed thresholds; This is the braking coefficient. , , They are respectively , , Three-phase differential current.

[0028] More preferably,

[0029] Fixed threshold Calculate using the following method:

[0030]

[0031] in , Take 50Hz. T For one week of wave duration, This is the setting for differential protection.

[0032] More preferably,

[0033] The braking coefficient is calculated as follows:

[0034]

[0035] In the formula, , These are the non-fault phase difference current and the fault phase difference current obtained according to the Berylon algorithm during a single-phase ground fault, respectively.

[0036] Secondly, this invention discloses an energy integral differential protection system based on a distributed parameter model, comprising:

[0037] The electrical quantity acquisition module on both sides of the line collects the instantaneous values ​​of three-phase voltage and three-phase current on both sides of the line in real time.

[0038] The local current estimation module calculates the local three-phase current at the same moment based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line.

[0039] The three-phase current differential current and differential current action quantity calculation module calculates the three-phase current differential current based on the real-time collected instantaneous value of the three-phase current on this side and the calculated value of the three-phase current on this side at the same time, and further calculates the three-phase differential current action quantity.

[0040] The differential protection judgment module uses the three-phase differential current action quantity to form the energy integral differential protection action criterion. When the three-phase differential current action quantity meets the differential protection action criterion, the differential protection is activated.

[0041] More preferably,

[0042] The dual-sided electrical quantity acquisition module collects real-time instantaneous values ​​of three-phase voltage and three-phase current on both sides of the line, including:

[0043] Collect the instantaneous values ​​of three-phase voltage and current at various times from the protection device on this side (i.e., side m), and set them as follows: , , , , , Through the signal transmission channel, the instantaneous values ​​of the three-phase voltage and current at the same time on the opposite side of the line, i.e., the nth side, are obtained and denoted as [missing information]. , , , , , .

[0044] More preferably,

[0045] The local current calculation module calculates the local three-phase current at the same moment based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line, including:

[0046] opposite side of the line tSubstituting the instantaneous values ​​of voltage and current at time t into the Berylon model equations, the m-side can be calculated. t Calculated value of three-phase current at time , , .

[0047] More preferably,

[0048] The three-phase differential current and differential current action calculation module calculates the three-phase differential current based on the real-time acquired instantaneous values ​​of the local three-phase current and the calculated values ​​of the local three-phase current at the same time, including:

[0049] Calculate the three-phase differential current at time t using the following formula:

[0050]

[0051] In the formula For the three-phase differential current at time t on side m, The three-phase sampling current at time t on side m is... To calculate the m-side according to the Berylon model t Calculated values ​​of three-phase current at any given time; Values or or , respectively represent , , Three phases.

[0052] More preferably,

[0053] The calculation of three-phase differential current action is based on three-phase current differential current, including:

[0054] The three-phase differential current is calculated using the following formula:

[0055]

[0056] in For three-phase differential current, Values or or , respectively represent , , Three phases, T It is one cycle time.

[0057] More preferably,

[0058] The differential protection judgment module uses the three-phase differential current action quantity to construct the energy integral differential protection action criterion. When the three-phase differential current action quantity meets the differential protection action criterion, the differential protection is activated, specifically including:

[0059] The energy integral differential protection action criterion is shown in the following formula:

[0060]

[0061] In the formula: For fixed thresholds; This is the braking coefficient. , , They are respectively , , Three-phase differential current.

[0062] More preferably,

[0063] Fixed threshold Calculate using the following method:

[0064]

[0065] in , Take 50Hz. T For one week of wave duration, This is the setting for differential protection.

[0066] More preferably,

[0067] The braking coefficient is calculated as follows:

[0068]

[0069] In the formula, , These are the non-fault phase difference current and the fault phase difference current obtained according to the Berylon algorithm during a single-phase ground fault, respectively.

[0070] Thirdly, the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory; characterized in that: the processor executes the computer program to implement the steps of the energy integral differential protection method based on the distributed parameter model.

[0071] Fourthly, the present invention discloses a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of an energy integral differential protection method based on a distributed parameter model.

[0072] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0073] This invention provides an energy integral differential protection method based on a distributed parameter model. This method solves the problems of frequency offset and harmonics in traditional Berylone phasor differential protection after faults in power electronic equipment such as new energy sources and flexible DC transmission, which lead to difficulties in extracting power frequency phasors and affect the sensitivity and speed of differential protection. This invention improves the differential protection performance in new energy transmission scenarios and is of great significance for enhancing the safety and stability of new energy transmission systems. Attached Figure Description

[0074] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0075] Figure 1 This is a schematic diagram of an energy integral differential protection method and system based on a distributed parameter model according to an embodiment of the present invention.

[0076] Figure 2 This is a diagram showing the distribution of fault voltage and current within the area.

[0077] Figure 3 Simulation system diagram.

[0078] Figure 4 This is a comparison chart of the calculation results. Detailed Implementation

[0079] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this invention are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0080] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0081] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0082] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0083] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0084] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0085] To address the technical problems existing in the prior art, this invention discloses an energy integral differential protection method based on a distributed parameter model, comprising the following steps:

[0086] Step 1: Real-time acquisition of instantaneous values ​​of three-phase voltage and three-phase current on both the local and opposite sides of the line;

[0087] Collect the instantaneous values ​​of three-phase voltage and current at various times from the protection device on this side (i.e., side m), and set them as follows: , , , , , Through the signal transmission channel, the instantaneous values ​​of the three-phase voltage and current at the same time on the opposite side of the line, i.e., the nth side, are obtained and denoted as [missing information]. , , , , , .

[0088] Step 2: Calculate the three-phase current at the same moment on this side based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line;

[0089] opposite side of the line tSubstituting the instantaneous values ​​of voltage and current at time t into the Berylon model equations, the m-side can be calculated. t Calculated value of three-phase current at time , , .

[0090] Step 3: Based on the real-time acquired instantaneous values ​​of the three-phase current on this side and the calculated values ​​of the three-phase current on this side at the same time, the differential current of the three-phase current is calculated.

[0091] Calculate the three-phase differential current at time t using the following formula:

[0092]

[0093] In the formula For the three-phase differential current at time t on side m, The three-phase sampling current at time t on side m is... To calculate the m-side according to the Berylon model t Calculated values ​​of three-phase current at any given time; Values or or , respectively represent , , Three phases.

[0094] Step 4: Calculate the three-phase differential current action based on the three-phase current differential current;

[0095] The three-phase differential current is calculated using the following formula:

[0096]

[0097] in For three-phase differential current, Values or or , respectively represent , , Three phases, T It is one cycle time.

[0098] Step 5: Construct an energy integral differential protection action criterion using the three-phase differential current action quantity. When the three-phase differential current action quantity satisfies the differential protection action criterion, the differential protection will operate.

[0099] The energy integral differential protection action criterion is shown in the following formula:

[0100]

[0101] In the formula: For fixed thresholds; This is the braking coefficient. , , They are respectively , , Three-phase differential current.

[0102] More preferably,

[0103] Fixed threshold Calculate using the following method:

[0104]

[0105] in , Take 50Hz. T For one week of wave duration, The differential protection setting is set by the user. Taking 300A as an example, the result is obtained using this method. =2.16(kA) 2 .

[0106] More preferably,

[0107] The braking coefficient is calculated as follows:

[0108]

[0109] In the formula, , These are the non-faulty phase difference current and the faulty phase difference current obtained according to the Berylon algorithm during a single-phase ground fault. Taking a 500kV line as an example, considering a certain margin, Take 0.01.

[0110] The present invention also discloses an energy integral differential protection system based on a distributed parameter model that utilizes the aforementioned differential protection method, including a line dual-side electrical quantity acquisition module, a local side current estimation module, a three-phase current differential current and differential current action quantity calculation module, and a differential protection judgment module;

[0111] The electrical quantity acquisition module on both sides of the line collects the instantaneous values ​​of three-phase voltage and three-phase current on both sides of the line in real time.

[0112] The local current estimation module calculates the local three-phase current at the same moment based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line.

[0113] The three-phase current differential current and differential current action quantity calculation module calculates the three-phase current differential current based on the real-time collected instantaneous value of the three-phase current on this side and the calculated value of the three-phase current on this side at the same time, and further calculates the three-phase differential current action quantity.

[0114] The differential protection judgment module uses the three-phase differential current action quantity to form the energy integral differential protection action criterion. When the three-phase differential current action quantity meets the differential protection action criterion, the differential protection is activated.

[0115] Example 1

[0116] Reference Figure 1 As one embodiment of the present invention, this embodiment provides an energy integral differential protection method based on a distributed parameter model, comprising:

[0117] 1. Collect the instantaneous values ​​of three-phase voltage and current at various times obtained by the protection device on this side (m side), and set them as follows: , , , , , Through the signal transmission channel, the instantaneous values ​​of the three-phase voltage and current at the same time on each of the n sides of the line are obtained, and denoted as [missing information]. , , , , , .

[0118] 2. Connect the nth side of the line t Substituting the instantaneous values ​​of voltage and current at time t into the Berylon model equations, the m-side can be calculated. t Calculated value of three-phase current at time , , By using the Beryllon model equations to deduce the current and voltage values ​​on the local side from the current and voltage values ​​on the other side, the influence of capacitor current can be greatly reduced.

[0119] 3. Calculate the three-phase differential current at time t:

[0120]

[0121] In the formula For the three-phase differential current at time t on side m, The three-phase sampling current at time t on side m is... To calculate the m-side (end of the line) according to the Berylon model t Calculated values ​​of three-phase current at any given time.

[0122] 4. Conventional Beryl differential protection, utilizing the solution The power frequency phasor is extracted to obtain the differential current value, which is then compared with the protection threshold to determine the protection action. Extracting the power frequency phasor for fault current in new energy sources is difficult. This invention utilizes time-domain information to perform square integration to calculate the differential current action, unaffected by frequency offset and harmonics.

[0123] Calculate differential flow motion using square integral algorithm

[0124]

[0125] in For three-phase differential current, T The time is one cycle. The protection device, after discrete sampling, converts the data into the following calculation of the differential current action.

[0126]

[0127] Where N represents the number of protection sampling points per cycle.

[0128] 5. In order to overcome the shortcomings of the Beryl differential criterion sensitivity being affected by the unbalanced differential current of the non-faulty phase in the single-phase ground fault within the zone, this invention proposes a protection criterion for braking quantity that uses a fixed threshold combined with the weight of the larger of the differential currents of the other two phases.

[0129] The energy integral differential protection action criterion is constructed using the three-phase differential current action quantity as follows:

[0130]

[0131] In the formula: For fixed thresholds; This is the braking coefficient.

[0132] To prevent maloperation of the protection due to differential current caused by unbalanced current during external faults and other operating conditions, the differential current setting is calculated using the following method based on the conventional differential current setting:

[0133]

[0134] in , Set the frequency to 50Hz. T For one week of wave duration, The differential protection settings are set by the user. When taking 300A, this method is used to obtain it. =2.16(kA) 2 .

[0135] The braking coefficient, which can overcome the influence of the unbalanced differential current of the non-faulted phases in the single-phase ground fault short circuit within the zone on the sensitivity of the Beryl differential criterion, is calculated as follows:

[0136]

[0137] , The two values ​​are the non-faulty phase differential current and the faulty phase differential current obtained by the Berylon algorithm during a single-phase ground fault. By calculating the ratio of the two, the braking coefficient of the non-faulty phase can be obtained by braking the faulty phase differential current. This ensures both reliable braking and sensitivity. The specific calculation method is as follows:

[0138] A fault diagram within the line area is shown below. Figure 2 As shown

[0139] In the picture u m ( t ), u n ( t ), i m ( t ), i n ( t ) represents the voltage and current on both sides of the line, i f ( t ) is the fault point current, τ m τ n Let F be the traveling wave time from terminal F to terminal m and from terminal F to terminal n, respectively. Taking a single-phase grounding of phase A as an example, the three-phase differential current expression can be obtained using the conventional Berylone differential method:

[0140]

[0141] To facilitate understanding, this equation is converted into phasor representation.

[0142]

[0143] in Fault phase difference flow calculated for the Berylon equation. The non-fault phase difference current calculated using the Beryllon equation, taking a 500kV line as an example: L0 = 0.0028632 H / km, L1 = 0.00090846 H / km, C0 = 0.008625 μF / km, C1 = 0.013699 μF / km. When a metallic short circuit occurs in phase A at the n-side outlet, there is...

[0144] , At this time, we obtain

[0145]

[0146] Considering a certain margin, Take 0.01.

[0147] It should be noted that the present invention provides an energy integral differential protection method based on a distributed parameter model. This method solves the problems of frequency deviation and harmonics after faults in power electronic equipment such as new energy sources and flexible DC power transmission, which lead to difficulties in extracting power frequency phasors and affect the sensitivity and speed of differential protection.

[0148] This embodiment also discloses a computer device / equipment / system, including a memory, a processor, and a computer program stored in the memory; characterized in that: the processor executes the computer program to implement the steps of the energy integral differential protection method based on the distributed parameter model.

[0149] This embodiment also discloses a computer-readable storage medium storing a computer program thereon, characterized in that the computer program, when executed by a processor, implements the steps of an energy integral differential protection method based on a distributed parameter model.

[0150] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0151] Example 2

[0152] Using PSCAD software to build a large-scale photovoltaic-storage grid-connected system model, such as Figure 3 As shown in the figure, the new energy side consists of three centralized photovoltaic systems with a capacity of 100MW and one centralized energy storage system with a capacity of 50MW. After being collected by the collection line, the voltage is stepped up to 500kV and connected to the power grid.

[0153] Taking the calculation result of phase A current in a phase-to-ground fault at the end of line A / B as an example, this method is compared with the conventional Beryl differential method. Figure 4 As shown, the fault occurred at 0.09s.

[0154] according to Figure 3The model shown simulates three-phase short circuit, two-phase grounding, phase-to-phase short circuit, and single-phase short circuit at four locations: k1 (new energy outlet side), k2 (line midpoint), k3 (system outlet side), and k4 (outside the zone). The simulation results are shown in Table 1.

[0155] Table 1. Simulation results of typical faults inside and outside the area

[0156]

[0157] As can be seen from the above experiments, this method has better protection performance than the traditional Beryl phasor differential protection.

[0158] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0159] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media are not limited to electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination thereof. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0160] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0161] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. An energy integral differential protection method based on a distributed parameter model, characterized in that, Includes the following steps: Step 1: Real-time acquisition of instantaneous values ​​of three-phase voltage and three-phase current on both the local and opposite sides of the line; Step 2: Calculate the three-phase current at the same moment on this side based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line; Step 3: Based on the real-time acquired instantaneous values ​​of the three-phase current on this side and the calculated values ​​of the three-phase current on this side at the same time, the differential current of the three-phase current is calculated. Step 4: Calculate the three-phase differential current action based on the three-phase current differential current; Step 5: Construct an energy integral differential protection action criterion using the three-phase differential current action quantity. When the three-phase differential current action quantity satisfies the differential protection action criterion, the differential protection operates. The differential protection action criterion is shown in the following formula: In the formula, For fixed thresholds; This is the braking coefficient. , , They are respectively , , Three-phase differential current, , These are the non-fault phase difference current and the fault phase difference current obtained according to the Berylon algorithm during a single-phase ground fault, respectively.

2. The energy integral differential protection method based on a distributed parameter model according to claim 1, characterized in that: In step 1, the instantaneous values ​​of the three-phase voltage and current of the protection device on this side (i.e., side m) are collected at various times, and set as follows: , , , , , Through the signal transmission channel, the instantaneous values ​​of the three-phase voltage and current at the same time on the opposite side of the line, i.e., the nth side, are obtained and denoted as [missing information]. , , , , , .

3. The energy integral differential protection method based on a distributed parameter model according to claim 2, characterized in that: In step 2, the opposite side of the line t Substituting the instantaneous values ​​of voltage and current at time t into the Berylon model equations, the m-side can be calculated. t Calculated value of three-phase current at time , , .

4. The energy integral differential protection method based on a distributed parameter model as described in claim 1, 2, or 3, characterized in that: In step 3, the three-phase differential current at time t is calculated according to the following formula: In the formula For the three-phase differential current at time t on side m, The three-phase sampling current at time t on side m is... To calculate the m-side according to the Berylon model t Calculated values ​​of three-phase current at any given time; Values or or , respectively represent , , Three phases.

5. The energy integral differential protection method based on a distributed parameter model according to claim 4, characterized in that: In step 4, the three-phase differential current is calculated according to the following formula: in For three-phase differential current, Values or or , respectively represent , , Three phases, T It is one cycle time.

6. The energy integral differential protection method based on a distributed parameter model according to claim 1, characterized in that: Fixed threshold Calculate using the following method: in , Take 50Hz. T For one week of wave duration, This is the setting for differential protection.

7. An energy integral differential protection system based on a distributed parameter model, comprising a line dual-side electrical quantity acquisition module, a local current estimation module, a three-phase current differential current and differential current action quantity calculation module, and a differential protection judgment module; characterized in that: The electrical quantity acquisition module on both sides of the line collects the instantaneous values ​​of three-phase voltage and three-phase current on both sides of the line in real time. The local current estimation module calculates the local three-phase current at the same moment based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line. The three-phase current differential current and differential current action quantity calculation module calculates the three-phase current differential current based on the real-time collected instantaneous value of the three-phase current on this side and the calculated value of the three-phase current on this side at the same time, and further calculates the three-phase differential current action quantity. The differential protection judgment module uses the three-phase differential current action quantity to construct the energy integral differential protection action criterion. When the three-phase differential current action quantity meets the differential protection action criterion, the differential protection operates. The energy integral differential protection action criterion is shown in the following formula: In the formula, For fixed thresholds; This is the braking coefficient. , , They are respectively , , Three-phase differential current; , These are the non-fault phase difference current and the fault phase difference current obtained according to the Berylon algorithm during a single-phase ground fault, respectively.

8. The energy integral differential protection system based on a distributed parameter model according to claim 7, characterized in that, The dual-sided electrical quantity acquisition module collects real-time instantaneous values ​​of three-phase voltage and three-phase current on both sides of the line, including: Collect the instantaneous values ​​of three-phase voltage and current at various times from the protection device on this side (i.e., side m), and set them as follows: , , , , , Through the signal transmission channel, the instantaneous values ​​of the three-phase voltage and current at the same time on the opposite side of the line, i.e., the nth side, are obtained and denoted as [missing information]. , , , , , .

9. The energy integral differential protection system based on a distributed parameter model according to claim 8, characterized in that, The local current calculation module calculates the local three-phase current at the same moment based on the instantaneous values ​​of the three-phase voltage and three-phase current on the opposite side of the line, including: opposite side of the line t Substituting the instantaneous values ​​of voltage and current at time t into the Berylon model equations, the m-side can be calculated. t Calculated value of three-phase current at time , , .

10. The energy integral differential protection system based on a distributed parameter model as described in claim 7, 8, or 9, characterized in that, The three-phase differential current and differential current action calculation module calculates the three-phase differential current based on the real-time acquired instantaneous values ​​of the local three-phase current and the calculated values ​​of the local three-phase current at the same time, including: Calculate the three-phase differential current at time t using the following formula: In the formula For the three-phase differential current at time t on side m, The three-phase sampling current at time t on side m is... To calculate the m-side according to the Berylon model t Calculated values ​​of three-phase current at any given time; Values or or , respectively represent , , Three phases.

11. The energy integral differential protection system based on a distributed parameter model according to claim 10, characterized in that, The calculation of three-phase differential current action is based on three-phase current differential current, including: The three-phase differential current is calculated using the following formula: in For three-phase differential current, Values or or , respectively represent , , Three phases, T It is one cycle time.

12. The energy integral differential protection system based on a distributed parameter model according to claim 7, characterized in that: Fixed threshold Calculate using the following method: in , Take 50Hz. T For one week of wave duration, This is the setting for differential protection.

13. A computer device, comprising a memory, a processor, and a computer program stored in the memory; characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1-6.

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

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