Time-domain distance protection method and system resistant to impact of transition resistance

Abstract

A time-domain distance protection method and system resistant to the impact of transition resistance. The used technical solution is: using voltage and current sampling sequences at a protection installation position to construct a time-domain equation, adjusting a zero-sequence current angle on the basis of system-related parameters, and solving a fault location and transition resistance; and determining whether a calculated fault distance is smaller than a preset value, and using same as a condition for triggering the action of protection. Therefore, the problem of time-domain distance protection overreaching caused by transition resistance is solved, thereby improving the applicability of distance protection of power transmission lines.

Description

A time domain distance protection method and system for resisting the influence of transition resistance Technical Field

[0001] The invention belongs to the field of power systems and relates to a relay protection method, in particular to a time domain distance protection method that is resistant to the influence of transition resistance. Background Art

[0002] As power systems rapidly evolve toward a high proportion of renewable energy and power electronic equipment, ensuring the reliability of protection on renewable energy transmission lines is becoming increasingly important for improving system stability. However, the current phase control, frequency deviation, and high harmonic characteristics exhibited by power electronic power supplies significantly affect the operating characteristics of traditional power frequency distance protection, even causing false or non-operation of distance protection, seriously impacting safe system operation.

[0003] In principle, time-domain distance protection is unaffected by the characteristics of the back-side power supply, offering significant advantages over traditional power-frequency distance protection. Existing methods, including those based on error weight matrices and improved differential equations, primarily aim to improve computational speed and accuracy. However, due to the mismatch in zero-sequence impedance angles on both sides of the fault point, time-domain distance protection can cause overshoot and false tripping when a fault passes through a transition resistor.

[0004] For example, ABB's patent application CN201780066228.2 in China discloses a time-domain distance protection method, which includes the following steps: obtaining a sampled value of a voltage at a measuring point on an electrical line, where a protection device for protecting the line is installed; obtaining a sampled value of a current at the measuring point; calculating an instantaneous measuring point voltage value specified by an operating standard of the protection device from the sampled values ​​of the voltage at the measuring point and the sampled values ​​of the current at the measuring point by using a measurement differential equation based on a time-domain lumped parameter model for the electrical line; calculating an instantaneous comparative voltage value specified by an operating standard of the protection device from the sampled values ​​of the voltage at the measuring point and the sampled values ​​of the current at the measuring point by using a comparison differential equation based on a time-domain lumped parameter model for the electrical line; and performing fault detection based on a comparison result of the instantaneous measuring point voltage value and the instantaneous comparative voltage value. This method does not explain the transition resistance situation, and the selection of relevant parameters is unclear.

[0005] ABB's patent application CN202010266162.5 in China discloses a polarity comparison-based time-domain distance protection method for transmission lines. This method obtains instantaneous measurement results of the local voltage and local current of the transmission line, obtains filtered measurement results of the local voltage and local current by performing low-pass filtering on the measurement results, obtains compensated voltage measurement results by performing a differential equation-based algorithm on the filtered measurement results, and performs fault detection by forming a ratio between the compensated voltage measurement results and the filtered voltage measurement results. If the ratio is a negative value less than a threshold, an internal fault is determined. Otherwise, an external fault is determined. However, this method is applicable to metallic faults and does not accurately describe faults containing transition resistance. It may still exceed the threshold in the case of a short-circuit fault with transition resistance.

[0006] Chinese patent application CN202011228262.5 discloses a time-domain distance protection method for wind farm transmission lines, specifically including the following steps: collecting the instantaneous values ​​of phase voltage, phase current, and zero-sequence current, each forming a signal sequence; constructing the signal sequence into a Hankel matrix and performing singular value decomposition on it to extract the component signals corresponding to the signal sequence; calculating the differential equation of the corresponding protection installation after the line fault occurs, and using the difference method to obtain the differential equation with the positive sequence resistance and inductance of the line from the fault point to the protection installation as unknown quantities; substituting the elements of the component signal of each electrical quantity into the equation and solving it to obtain the estimated values ​​of the resistance parameter and the inductance parameter, and calculating the accurate resistance parameter and inductance parameter based on the sampled data. This patented technology uses an internal improved differential equation, but the differential equation described in this method is not suitable for describing the fault characteristics of a short circuit containing a transition resistor, so it has poor applicability when a fault occurs through a transition resistor.

[0007] Therefore, it is very important to study a time domain distance protection method that is resistant to the influence of transition resistance. Summary of the Invention

[0008] In order to avoid the overrunning malfunction problem caused by a transition resistance fault, the present invention provides an improved time domain distance protection method that is resistant to the influence of transition resistance.

[0009] A time domain distance protection method for resisting the influence of transition resistance, characterized by comprising the following steps:

[0010] (1) Collect the instantaneous values ​​of the fault phase current and voltage at the protection installation and construct the fault location equation using the time domain information;

[0011] (2) Calculating the zero-sequence current angle and the adjusted zero-sequence current value based on system parameters;

[0012] (3) According to the adjusted zero-sequence current value, the equivalent transition resistance voltage drop in the fault distance equation is adjusted to solve the fault distance, and compared with the preset value of the protection range. When the fault distance is less than the preset value of the protection range, the time domain distance protection action is triggered.

[0013] The present invention further includes the following preferred embodiments.

[0014] In step (1), the fault location equation is constructed using time domain information:

[0015] Where u m (t), i m (t) are the instantaneous values ​​of the fault phase voltage and current at the protection installation location, i m0 (t) is the instantaneous value of zero sequence current, K r is the resistance zero sequence compensation coefficient, K l is the zero-sequence inductance compensation coefficient, r0 and l0 are the zero-sequence resistance and inductance of the line per unit length, r1 and l1 are the positive-sequence resistance and inductance of the line per unit length, x is the fault distance, R' F is the equivalent transition resistance.

[0016] Resistance zero-sequence compensation coefficient K r =(r0-r1) / 3r1;

[0017] Inductance zero-sequence compensation coefficient K l =(l0-l1) / 3l1.

[0018] In step (2), the adjusted zero-sequence current value is calculated according to the following formula: m0 (t)'=i m0 (t)*cosθ+(i m0 (t)-i m0 (t-△t)) / (△t)*sinθ / 2*π*f

[0019] Among them, i m0 (t) is the value of zero-sequence current sampling at time t, △t is the sampling interval, f is the frequency, which is 50HZ, θ is the zero-sequence current angle, i m0 (t)' is the value of the adjusted zero-sequence current at time t.

[0020] The adjusted zero-sequence current value is used to adjust the equivalent transition resistance voltage drop in the fault location equation in step (1).

[0021] The zero-sequence current angle θ is calculated according to the following formula:

[0022] where Z N0 is the equivalent zero-sequence impedance of the opposite system, Z M0is the zero-sequence impedance of the local system, Z L0 is the line zero-sequence impedance, and θ is the calculated zero-sequence current adjustment angle.

[0023] The fault location equation after adjusting the zero-sequence current value is as follows:

[0024] i' m0 (t) is the zero-sequence current after adjustment,

[0025] The fault distance x is compared with the preset value X of the protection range. set For comparison, when x <X set It is determined that the fault occurs within the protection range and the time domain distance protection action is triggered.

[0026] X set The value is determined based on actual conditions, generally 80% of the total line length.

[0027] The present application also seeks to protect a time domain distance protection system resistant to the influence of transition resistance, comprising a phase current and phase voltage acquisition module, a fault distance equation construction module, a post-fault zero-sequence current adjustment module, a fault distance calculation module, and a protection action judgment module, characterized in that:

[0028] The phase current and phase voltage acquisition module is used to collect the instantaneous values ​​of the fault phase current and voltage at the protection installation in real time;

[0029] The fault location equation construction module is used to construct a fault location equation using time domain information;

[0030] The post-fault zero-sequence current adjustment module is used to calculate the adjusted zero-sequence current value according to the post-fault zero-sequence current angle;

[0031] The fault distance calculation module is used to calculate the fault distance according to the fault distance equation and the adjusted zero-sequence current value;

[0032] The protection action judgment module is used to determine the fault distance x and the protection range preset value X. set To determine whether to trigger the time domain distance protection action.

[0033] More preferably,

[0034] The post-fault zero-sequence current adjustment module further includes a zero-sequence current angle calculation unit and a zero-sequence current adjustment value calculation unit;

[0035] The zero-sequence current angle calculation unit is used to calculate the zero-sequence current angle after a fault according to the following formula:

[0036] where Z N0 is the zero-sequence impedance of the equivalent system on the opposite side, Z M0is the equivalent zero-sequence impedance of the local system, f is the frequency, which is 50 Hz, and θ is the zero-sequence current angle;

[0037] The zero-sequence current adjustment value calculation unit is used to calculate the adjusted zero-sequence current value according to the following formula: m0 (t)'=i m0 (t)*cosθ+(i m0 (t)-i m0 (t-△t)) / (△t)*sinθ / 2*π*f

[0038] Among them, i m0 (t) is the value of zero-sequence current sampling at time t, △t is the sampling interval, f is the frequency, which is 50HZ, θ is the zero-sequence current angle, i m0 (t)' is the adjusted zero-sequence current value.

[0039] A computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to perform the distance protection method described above.

[0040] A computing device, comprising:

[0041] One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for executing the distance protection method.

[0042] Compared to existing technologies, the present invention provides an improved time-domain distance protection method and system that is resistant to the effects of transition resistance. This method calculates the zero-sequence current adjustment angle based on system parameters and provides a zero-sequence current angle compensation method. This solves the problem of false overrunning outside the time-domain distance protection zone caused by transition resistance, improving the operational stability and reliability of the time-domain distance protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is a flow chart of the time domain distance protection method against the influence of transition resistance of the present invention

[0044] Figure 2 is a schematic diagram of a single-phase short-circuit system for a transmission line;

[0045] Figure 3 is a fault voltage distribution vector diagram;

[0046] Figure 4 is a schematic diagram of a zero-sequence network for a transmission line fault;

[0047] Figure 5 Transmission line fault simulation system diagram

[0048] Figure 6 shows the distance measurement results when conventional time domain distance protection is used when a metallic short circuit fault occurs in F1 of Figure 5.

[0049] Figure 7 shows the distance measurement results after adjusting the angle by -5° using the improved time domain distance protection when a metallic fault occurs on F1.

[0050] Figure 8 shows the distance measurement results when conventional time domain distance protection is used when a 5Ω transition resistance ground short circuit fault occurs in F1.

[0051] Figure 9 shows the distance measurement results after the improved time domain distance protection is adjusted to -5° when a 5Ω transition resistance ground short circuit fault occurs in F1.

[0052] Figure 10 shows the distance measurement results when conventional time domain distance protection is used when a 10Ω transition resistance ground short circuit fault occurs in F1.

[0053] Figure 11 shows the distance measurement results after the improved time domain distance protection is adjusted to -5° when a 10Ω transition resistance ground short circuit fault occurs in F1.

[0054] Figure 12 shows the distance measurement results when conventional time domain distance protection is used when a 20Ω transition resistance ground short circuit fault occurs in F1.

[0055] Figure 13 shows the distance measurement results after the improved time domain distance protection is adjusted to -5° when a 20Ω transition resistance ground short circuit fault occurs in F1. DETAILED DESCRIPTION

[0056] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0057] FIG1 is a flow chart of an improved time domain distance protection method for resisting the influence of transition resistance according to the present invention, which comprises the following steps:

[0058] (1) Construct the time domain distance protection equation.

[0059] For a single-phase metallic ground fault, based on the line lumped parameter model shown in Figure 2, the fault location equation is constructed using the time domain sampling information at the protection installation:

[0060] In the above formula, u m (t), i m (t) are the instantaneous values ​​of the fault phase voltage and current at the protection installation location, i m (t) is the instantaneous value of the sampling current, K r =(r0-r1) / 3r1 is the resistance zero sequence compensation coefficient, Kl =(l0-l1) / 3l1 is the zero-sequence inductance compensation coefficient, r0 and l0 are the zero-sequence resistance and inductance values ​​per unit length of the line respectively, r1 and l1 are the positive-sequence resistance and inductance values ​​per unit length of the line respectively, and x is the fault distance.

[0061] The fault distance x is compared with the preset value X of the protection range. set For comparison, when x <X set It is considered that the fault occurs within the protection range and the time domain distance protection action is triggered.

[0062] From the above formula, we can see that only the fault distance x is an unknown number. By using the voltage and current sampling values ​​within a period of time after the fault to construct an equation, the fault distance can be obtained by the least squares method and compared with the preset value X of the protection range. set For comparison, when x <X set It can be considered that the fault occurs within the protection range, triggering the time domain distance protection action.

[0063] For a single-phase grounding fault through a transition resistor, based on the lumped parameter line model shown in Figure 2, the fault location equation is constructed using the time domain sampling information at the protection installation:

[0064] Where i f (t) is the fault point current, R' F is the equivalent transition resistance, and the other variables have the same meanings as in formula (5).

[0065] In formula (6), i f (t) is the current flowing through the transition resistance of the fault point. Since this quantity cannot be directly obtained, the zero-sequence current i collected by the protection on this side is used. m0 Substitution is a method commonly used in existing technologies. When the zero-sequence impedance angles on both sides of the fault point are consistent, i m0 replace i f Only affects R' F Calculate the value, i.e. R' F =cR F , where R F is the actual transition resistance and will not affect the fault location x. However, when the zero-sequence equivalent impedance angles on both sides of the fault point are inconsistent, especially when a fault occurs at the end of the line, the zero-sequence impedance angles on both sides of the fault point differ greatly, which will have a significant impact on the value of the fault location x. This situation is further discussed below.

[0066] As shown in Figure 3, the zero-sequence network diagram of the system, the following equation can be obtained:

[0067] in, To measure the voltage at the protection installation, Measuring current, To measure zero-sequence current, k is the zero-sequence compensation coefficient Z0 and Z1 are the zero-sequence and positive-sequence impedances of the line respectively, α is the fault distance, which is the fault distance / total line length. is the current flowing through the fault point, R F is the transition resistance.

[0068] Substituting the zero-sequence current of the local side for the zero-sequence current of the fault point yields:

[0069] R' F is the equivalent transition resistance, and the system voltage distribution diagram shown in Figure 3 can be obtained from formula (8). If Angle greater than The calculated result is too low, resulting in far-end overtaking.

[0070] (2) Compensation of zero-sequence current angle on this side and solving fault distance

[0071] To prevent terminal misoperation, a negative angle is compensated based on the zero-sequence current on this side to reduce the zero-sequence current angle used in the equation. As shown in Figure 4, the zero-sequence current satisfies the following relationship

[0072] where Z N0 is the equivalent zero-sequence impedance of the opposite system, generally the zero-sequence impedance of the opposite step-down transformer, Z M0 is the zero-sequence impedance of the local system, generally the zero-sequence impedance of the boost transformer on this side, Z L0 is the line zero-sequence impedance, and θ is the calculated zero-sequence current adjustment angle.

[0073] Considering the maximum compensation angle at the end of the line to prevent overtaking, combined with formula (9), when α = 1, the compensation angle is:

[0074] Furthermore, the zero-sequence current after compensation is obtained: i m0 (t)'=i m0 (t)*cosθ+(i m0 (t)-i m0 (t-△t)) / (△t)*sinθ / 2*π*f

[0075] where i m0 (t) is the value of zero-sequence current sampling at time t, △t is the sampling interval, f is the frequency, which is 50HZ, θ is the zero-sequence current angle, i m0 (t)' is the value of the zero-sequence current at point k after adjustment. The zero-sequence current sampling value in the fault location equation in step (1) is replaced by the adjusted zero-sequence current value.

[0076] (3) Protection action judgment

[0077] The fault distance x is compared with the preset value X of the protection range. set For comparison, when x <X set It is determined that the fault occurs within the protection range and the time domain distance protection action is triggered.

[0078] The present application also claims protection for a time domain distance protection system based on the distance protection method that is resistant to the influence of transition resistance, comprising a phase current and phase voltage acquisition module, a fault distance equation construction module, a post-fault zero-sequence current adjustment module, a fault distance calculation module, and a protection action judgment module, characterized in that:

[0079] The phase current and phase voltage acquisition module is used to collect the instantaneous values ​​of the fault phase current and voltage at the protection installation in real time;

[0080] The fault location equation construction module is used to construct a fault location equation using time domain information;

[0081] The post-fault zero-sequence current adjustment module is used to calculate the adjusted zero-sequence current value according to the post-fault zero-sequence current angle;

[0082] The fault distance calculation module is used to calculate the fault distance according to the fault distance equation and the adjusted zero-sequence current value;

[0083] The protection action judgment module is used to determine the fault distance x and the protection range preset value X. set To determine whether to trigger the time domain distance protection action.

[0084] The post-fault zero-sequence current adjustment module further includes a zero-sequence current angle calculation unit and a zero-sequence current adjustment value calculation unit;

[0085] The zero-sequence current angle calculation unit calculates the zero-sequence current angle after a fault according to the following formula:

[0086] where Z N0 is the zero-sequence impedance of the equivalent system on the opposite side, Z M0 is the equivalent zero-sequence impedance of the local system, f is the frequency, which is 50 Hz, and θ is the zero-sequence current angle;

[0087] The zero-sequence current adjustment value calculation unit is used to calculate the adjusted zero-sequence current value according to the following formula: m0 (t)'=i m0 (t)*cosθ+(i m0 (t)-i m0 (t-△t)) / (△t)*sinθ / 2*π*f

[0088] Among them, i m0(t) is the value of zero-sequence current sampling at time t, △t is the sampling interval, f is the frequency, which is 50HZ, θ is the zero-sequence current angle, i m0 (t)' is the adjusted zero-sequence current value.

[0089] In another embodiment, the above-mentioned time domain distance protection system resistant to the influence of transition resistance includes: a processor, wherein the processor is used to execute the above-mentioned program modules and units stored in the memory, including: a phase current and phase voltage acquisition module, a fault distance measurement equation construction module, a post-fault zero-sequence current adjustment module, a fault distance calculation module, a protection action judgment module, a zero-sequence current angle calculation unit and a zero-sequence current adjustment value calculation unit.

[0090] A computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to perform the distance protection method described above.

[0091] Simulation Verification

[0092] The experiment was conducted on the 220kV simulation system shown in Figure 5. The line length was 20km, the zero-sequence impedance per unit length was 0.323+j1.2Ω, the positive-sequence impedance was 0.0705+j0.4Ω, the main transformer capacity on this side was 280WM, and the main transformer capacity on the opposite side was 3000WM. The short-circuit time was 3s, the fault location was the line end F1, the short-circuit type was a single-phase grounding fault, the protection range was 80% of the line length, and the adjustment angle was calculated based on the line parameters to be -5°. The simulation ranging results are shown in the figure and summarized in the following table. Figure 6 in the table is the ranging result diagram when conventional time domain distance protection is used when a metallic short circuit fault occurs in Figure 5F1, Figure 7 is the ranging result diagram when the improved time domain distance protection is used to adjust the angle to -5° when a metallic fault occurs in F1, Figure 8 is the ranging result diagram when conventional time domain distance protection is used when a 5Ω transition resistance grounding short circuit fault occurs in F1, Figure 9 is the ranging result diagram when the improved time domain distance protection is used to adjust the angle to -5° when a 5Ω transition resistance grounding short circuit fault occurs in F1, and Figure 10 Figure 5 shows the ranging results when conventional time domain distance protection is used when a 10Ω transition resistance ground short circuit fault occurs on F1. Figure 11 shows the ranging results when the improved time domain distance protection is used after the angle is adjusted to -5° when a 10Ω transition resistance ground short circuit fault occurs on F1. Figure 12 shows the ranging results when conventional time domain distance protection is used when a 20Ω transition resistance ground short circuit fault occurs on F1. Figure 13 shows the ranging results when the improved time domain distance protection is used after the angle is adjusted to -5° when a 20Ω transition resistance ground short circuit fault occurs on F1.

[0093] Table 1 Calculation results of improved time domain distance protection

[0094] The distance measurement results show that for metallic faults, the distance measurement results remain unchanged before and after the angle adjustment. When the line passes through a transition resistance fault, the distance measurement results of time-domain distance protection, which does not trip based on the zero-sequence current angle, are low, which can easily lead to false protection operation. The improved time-domain distance protection provides more accurate distance measurement results after adjusting the zero-sequence current angle, which can solve the problem of distance protection end-of-line overshoot. The following table compares the operation of conventional time-domain distance protection at the end of the line for different transition resistance faults:

[0095] Table 2 Action status comparison table

[0096] It can be seen from the simulation results that the present invention effectively solves the distance protection overrun problem caused by transition resistance.

[0097] The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0098] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination thereof. As used herein, a computer-readable storage medium is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

[0099] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions to be stored in the computer-readable storage medium in each computing / processing device.

[0100] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state 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++, and conventional procedural programming languages ​​such as "C" language or similar programming languages. Computer-readable program instructions may be executed entirely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or entirely on a remote computer or server. In the case of 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., utilizing an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be personalized by utilizing the state information of the computer-readable program instructions. The electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A time domain distance protection method against the influence of transition resistance, characterized in that: The following steps are involved: (1) Collect the instantaneous values ​​of the fault phase current and voltage at the protection installation and construct the fault location equation using the time domain information; (2) Calculating the zero-sequence current angle and the adjusted zero-sequence current value based on system parameters; (3) According to the adjusted zero-sequence current value, the equivalent transition resistance voltage drop in the fault distance equation is adjusted to solve the fault distance, and compared with the preset value of the protection range. When the fault distance is less than the preset value of the protection range, the time domain distance protection action is triggered.

2. The time domain distance protection method against transition resistance influence according to claim 1, characterized in that: In step (1), the fault location equation is constructed using time domain information: Where u m (t), i m (t) are the instantaneous values ​​of the fault phase voltage and current at the protection installation location, i m0 (t) is the instantaneous value of zero sequence current, K r is the resistance zero sequence compensation coefficient, K l is the zero-sequence inductance compensation coefficient, r0 and l0 are the zero-sequence resistance and inductance of the line per unit length, r1 and l1 are the positive-sequence resistance and inductance of the line per unit length, x is the fault distance, R' F is the equivalent transition resistance.

3. The time domain distance protection method against transition resistance influence according to claim 2, characterized in that: Resistance zero-sequence compensation coefficient K r =(r0-r1) / 3r1; Inductance zero-sequence compensation coefficient K l =(l0-l1) / 3l1.

4. The time domain distance protection method against transition resistance influence according to claim 1 or 2, characterized in that: In step (2), the adjusted zero-sequence current value is calculated according to the following formula: i m0 (t)'=i m0 (t)*cosθ+(i m0 (t)-i m0 (t-△t)) / (△t)*sinθ / 2*π*f Among them, i m0 (t) is the value of zero-sequence current sampling at time t, △t is the sampling interval, f is the frequency, which is 50HZ, θ is the zero-sequence current angle, i m0 (t)' is the zero-sequence current value after adjustment; The adjusted zero-sequence current value is used to adjust the equivalent transition resistance voltage drop in the fault location equation in step (1).

5. The time domain distance protection method against transition resistance influence according to claim 4, characterized in that: The zero-sequence current angle θ is calculated according to the following formula: where Z N0 is the equivalent zero-sequence impedance of the opposite system, Z M0 is the equivalent zero-sequence impedance of the local system, Z L0 is the line zero-sequence impedance, and θ is the calculated zero-sequence current adjustment angle.

6. The time domain distance protection method against the influence of transition resistance according to claim 5, characterized in that: The fault location equation after adjusting the zero-sequence current value is as follows: i' m0 (t) is the adjusted zero-sequence current; The fault distance x is compared with the preset value X of the protection range. set For comparison, when x <X set It is determined that the fault occurs within the protection range and the time domain distance protection action is triggered.

7. The time domain distance protection method against transition resistance influence according to claim 6, characterized in that: X set The value is determined based on actual conditions, generally 80% of the total line length.

8. A time-domain distance protection system resistant to transition resistance, comprising a phase current and phase voltage acquisition module, a fault distance equation construction module, a post-fault zero-sequence current adjustment module, a fault distance calculation module, and a protection action judgment module, characterized in that: The phase current and phase voltage acquisition module is used to collect the instantaneous values ​​of the fault phase current and voltage at the protection installation in real time; The fault location equation construction module is used to construct a fault location equation using time domain information; The post-fault zero-sequence current adjustment module is used to calculate the adjusted zero-sequence current value according to the post-fault zero-sequence current angle; The fault distance calculation module is used to calculate the fault distance according to the fault distance equation and the adjusted zero-sequence current value; The protection action judgment module is used to determine the fault distance x and the protection range preset value X. set To determine whether to trigger the time domain distance protection action.

9. The time domain distance protection system resistant to transition resistance influence according to claim 8, characterized in that: The post-fault zero-sequence current adjustment module further includes a zero-sequence current angle calculation unit and a zero-sequence current adjustment value calculation unit; The zero-sequence current angle calculation unit is used to calculate the zero-sequence current angle after a fault according to the following formula: where Z N0 is the zero-sequence impedance of the equivalent system on the opposite side, Z M0 is the equivalent zero-sequence impedance of the local system, f is the frequency, which is 50 Hz, and θ is the zero-sequence current angle; The zero-sequence current adjustment value calculation unit is used to calculate the adjusted zero-sequence current value according to the following formula: i m0 (t)'=i m0 (t)*cosθ+(i m0 (t)-i m0 (t-△t)) / (△t)*sinθ / 2*π*f Among them, i m0 (t) is the value of zero-sequence current sampling at time t, △t is the sampling interval, f is the frequency, which is 50HZ, θ is the zero-sequence current angle, i m0 (t)' is the adjusted zero-sequence current value.

10. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any one of the methods according to claims 1-7.

11. A computing device, characterized in that include: One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing any of the methods according to claims 1-7.

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