Distance protection method and system based on transient and steady state feature fusion criterion

Abstract

The invention discloses a distance protection method based on transient and steady state feature fusion criterion, and relates to the technical field of relay protection, and the method comprises the steps: outputting various phasor values based on a data sampling value of a protection installation position, and outputting the supply and reception conditions of a power supply connected with the protection installation position according to an included angle between a positive sequence voltage and a positive sequence current before a fault; dynamically adjusting the compensation angle based on the supply and receiving conditions of a power supply connected to the protection installation position; determining a fault direction by using output results of the voltage variation and the current variation after the fault; and the action range of the distance relay is adjusted according to the power supply condition and the fault direction of the power supply. According to the method, through dynamic compensation and action range optimization, the adaptability and reliability of the distance protection device in a complex power system are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection, and in particular to a distance protection method and system based on transient and steady-state feature fusion criteria. Background Art

[0002] With the large-scale integration of renewable energy, the fault characteristics of power systems have changed significantly. Unlike traditional synchronous generators, renewable energy sources are connected to the grid through power electronic equipment, resulting in fault currents with limited amplitude, controlled phase, and high harmonic content. Traditional distance protection is typically based on impedance characteristics. The fault current, provided by the synchronous generator, has high amplitude and a well-defined phase relationship. However, with the integration of renewable energy, the amplitude of the fault current is significantly reduced due to the current limiting control of power electronic equipment, and the phase may shift depending on the control strategy. In particular, when local reactive power support is insufficient at renewable energy sites, the phase relationship between system voltage and current becomes further complicated. Adjusting the protection range by simply shifting it by a fixed angle has limited improvement in protection performance. In recent years, there have been numerous cases of improper phase-to-phase fault distance protection due to renewable energy integration, exposing the limitations of traditional distance protection methods and posing a potential threat to the safe and stable operation of the power grid. Therefore, to address the new challenges brought about by renewable energy integration, in-depth research on new distance protection methods is urgently needed to ensure the safe and stable operation of the power grid. Summary of the Invention

[0003] In view of the above-mentioned problems, the present invention is proposed.

[0004] Therefore, the technical problems solved by the present invention are: the existing distance protection method has insufficient adaptability to new energy access scenarios, rigid fixed compensation mechanism, invalid setting principle, and how to improve the reliability of direction determination.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: a distance protection method based on transient and steady-state characteristic fusion criteria, comprising outputting various types of phasor values ​​based on data sampling values ​​at the protection installation, and outputting the supply and reception conditions of the power supply connected to the protection installation according to the angle between the positive-sequence voltage and the positive-sequence current before the fault; dynamically adjusting the compensation angle based on the supply and reception conditions of the power supply connected to the protection installation; determining the fault direction by utilizing the output results of the voltage change and the current change after the fault; adjusting the operating range of the distance relay according to the supply and reception conditions of the power supply and the fault direction; the outputting various types of phasor values ​​comprises filtering and Fourier transforming the sampled data, and outputting phase voltage phasor values ​​and phase current phasor values; the various types of phasor values ​​comprise phase voltage phasor, phase current phasor, phase-to-phase voltage phasor, phase-to-phase current phasor, positive-sequence voltage phasor and positive-sequence current phasor.

[0006] As a preferred solution of the distance protection method based on transient and steady-state feature fusion criteria described in the present invention, the output of various types of phasor values ​​includes filtering based on the phase voltage and phase current sampling values ​​at the protection installation, processing the phase voltage and phase current using a differential filter, and performing Fourier transform on the filtered sampling values ​​to output the phase voltage phasor value and the phase current phasor value.

[0007] As a preferred solution of the distance protection method based on transient and steady-state feature fusion criteria described in the present invention, the supply and receiving conditions of the power supply connected to the output protection installation location include: based on the positive-sequence voltage phasor and the positive-sequence current phasor, the angle between the positive-sequence voltage phasor and the positive-sequence current phasor before the output fault is compared with the judgment threshold value, and the judgment threshold value is a preset angle value. If the angle is less than the judgment threshold value, the power supply connected to the protection installation location is judged to be the supply-end power supply; if the angle is greater than or equal to the judgment threshold value, the power supply connected to the protection installation location is judged to be the receiving-end power supply.

[0008] As a preferred solution of the distance protection method based on transient and steady-state feature fusion criteria described in the present invention, the dynamic adjustment of the compensation angle includes selecting different compensation strategies according to the supply and reception conditions of the power supply connected to the protection installation location, and determining the supply and reception conditions based on the phase relationship between the positive-sequence voltage phasor value and the positive-sequence current phasor value before the fault. If it is determined to be the supply-end power supply, the first angle compensation method is adopted; if it is determined to be the receiving-end power supply, the second angle compensation method is adopted.

[0009] As a preferred solution of the distance protection method based on transient and steady-state feature fusion criteria described in the present invention, the output results of the post-fault voltage change and current change include outputting the post-fault voltage change based on the sampling values ​​of the voltage at the protection installation at the current moment and the voltage at the protection installation one cycle ahead, and outputting the post-fault current change based on the sampling values ​​of the current at the protection installation at the current moment and the current at the protection installation one cycle ahead, and determining the fault direction based on the post-fault voltage change and the post-fault current change.

[0010] As a preferred solution of the distance protection method based on transient and steady-state feature fusion criteria described in the present invention, the fault direction is determined based on the phase relationship between the measured voltage change and the measured current change after the fault. If the phases of the measured voltage change and the measured current change are consistent, it is determined to be a reverse fault; if the phases of the measured voltage change and the measured current change are opposite, it is determined to be a forward fault.

[0011] As a preferred solution of the distance protection method based on transient and steady-state characteristic fusion criteria described in the present invention, the adjustment of the action range of the distance relay includes selecting a corresponding action equation based on the determined fault direction. If it is determined to be a forward fault, the forward action characteristic equation is adopted; if it is determined to be a reverse fault, the reverse action characteristic equation is adopted. The action characteristic equation is determined by the relationship between the operating voltage and the distance protection setting value.

[0012] Another object of the present invention is to provide a distance protection system based on transient and steady-state characteristic fusion criteria, which can determine the fault direction by utilizing the output results of the voltage change and current change after the fault, thereby solving the problem of poor reliability of direction judgment in current distance protection technology.

[0013] As a preferred solution of the distance protection system based on transient and steady-state feature fusion criteria described in the present invention, it includes: a state perception module, a dynamic compensation decision module, and a fault response and protection module; the state perception module is used to collect electrical quantity data at the protection installation in real time, and outputs the key phasors of phase voltage phasor, phase current phasor, phase-to-phase voltage phasor, phase-to-phase current phasor, positive-sequence voltage phasor and positive-sequence current phasor according to the noise elimination filtering and phasor conversion processing of the acquired phase voltage and phase current sampling values, and uses the angle between the positive-sequence voltage phasor value and the positive-sequence current phasor value to determine the supply and reception status of the power supply connected to the protection installation; the dynamic compensation decision module is used to determine the protection installation based on the protection installation determined by the state perception module. The protection parameters are dynamically adjusted according to the supply and reception conditions of the power supply at the installation location, and the corresponding compensation strategy is selected according to the supply and reception conditions of the power supply. If it is determined to be the power supply at the supply end, the first angle compensation method is adopted; if it is determined to be the power supply at the receiving end, the second angle compensation method is adopted; the fault response and protection module is used to determine the fault direction by measuring the phase relationship between the voltage change and the current change after the output fault. If the phasor directions of the two are consistent, it is determined to be a reverse fault. Otherwise, if the phasor directions of the two are opposite, it is determined to be a forward fault. The action range of the distance relay is adjusted according to the determined fault direction, and the corresponding distance relay action equation is selected. The forward action characteristic equation is adopted in the case of a forward fault, and the reverse action characteristic equation is adopted in the case of a reverse fault.

[0014] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement a distance protection method based on a transient state feature fusion criterion.

[0015] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a distance protection method based on a transient state characteristic fusion criterion.

[0016] Beneficial effects of the present invention: The present invention provides a distance protection method based on transient and steady-state feature fusion criteria, which outputs various types of phasor values ​​based on the data sampling values ​​at the protection installation location, and outputs the supply and reception conditions of the power supply at the protection installation location according to the angle between the positive-sequence voltage and the positive-sequence current before the fault, thereby improving adaptability to complex power grids and preventing false operations. Based on the supply and reception conditions of the power supply at the protection installation location, the compensation angle is dynamically adjusted, the protection action boundary is optimized, and the reliability under complex fault conditions is improved. The output results of the voltage change and current change after the fault are used to determine the fault direction, thereby improving the speed and accuracy of the direction judgment. According to the supply and reception conditions of the power supply and the fault direction, the action range of the distance relay is adjusted to make the protection range more accurate and enhance the reliability of the protection system. The present invention achieves better results in terms of the accuracy of fault direction judgment, the adaptability of the protection range and the adaptability of the complex power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is an overall flow chart of a distance protection method based on transient and steady-state feature fusion criteria provided in the first embodiment of the present invention.

[0019] Figure 2 A schematic diagram of a new energy access system for a distance protection method based on transient and steady-state feature fusion criteria provided by the first embodiment of the present invention.

[0020] Figure 3 A phasor relationship diagram of positive-sequence voltage and positive-sequence current before a fault of a distance protection method based on transient-stable feature fusion criteria is provided in the first embodiment of the present invention.

[0021] Figure 4 A schematic diagram of an additional network for a forward fault of a distance protection method based on transient and steady-state feature fusion criteria provided by the first embodiment of the present invention.

[0022] Figure 5 A schematic diagram of an additional network for reverse faults of a distance protection method based on transient and steady-state feature fusion criteria provided by the first embodiment of the present invention.

[0023] Figure 6 A schematic diagram of the post-fault distance protection action area of ​​a distance protection method based on transient and steady-state feature fusion criteria provided in the first embodiment of the present invention.

[0024] Figure 7 This is a voltage and current waveform diagram of a BC phase-to-phase fault outside the reverse zone on the system side of a distance protection method based on transient and steady-state feature fusion criteria provided by the second embodiment of the present invention.

[0025] Figure 8 A schematic diagram of the angle of phase-to-phase current leading phase-to-phase voltage for a BC phase-to-phase fault outside the reverse zone on the system side according to a distance protection method based on transient and steady-state feature fusion criteria provided in the second embodiment of the present invention.

[0026] Figure 9 This is a schematic diagram of the results of the BC phase-to-phase fault direction element outside the system-side reverse zone of a distance protection method based on transient and steady-state feature fusion criteria provided by the second embodiment of the present invention.

[0027] Figure 10 This is a schematic diagram of the results of distance element discrimination for a BC phase-to-phase fault outside the reverse zone of a system side according to a distance protection method based on transient and steady state feature fusion criteria provided by the second embodiment of the present invention.

[0028] Figure 11 A structural diagram of a simulation model of an offshore wind power flexible DC transmission project, which provides a distance protection method based on transient and steady-state characteristic fusion criteria, according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0029] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0030] Example 1, with reference to Figures 1-6 , which is an embodiment of the present invention, provides a distance protection method based on transient and steady-state feature fusion criteria, including:

[0031] S1: Output various types of phasor values ​​based on the data sampling values ​​at the protection installation location, and output the supply and reception conditions of the power supply connected to the protection installation location according to the angle between the positive sequence voltage and the positive sequence current before the fault.

[0032] Furthermore, outputting various types of phasor values ​​includes filtering based on the phase voltage and phase current sampling values ​​at the protection installation, processing the phase voltage and phase current using a differential filter, and performing Fourier transform on the filtered sampling values ​​to output the phase voltage phasor value and the phase current phasor value.

[0033] The phase voltage sampling values ​​and phase current sampling values ​​are filtered to eliminate noise interference. The phase voltage is expressed as follows using a differential filter:

[0034] y(n)=k1·x(n)+k2·x(n-1)

[0035] Among them, y(n) is the voltage value output by the filter at time ∈, k1 is the filter coefficient, set to 1, x(n) is the voltage value input to the system at time n, k2 is the filter coefficient, set to 0.5.

[0036] The phase current is expressed using a differential filter as:

[0037] y(n)'=k3·x(n)'+k4·x(n-1)'

[0038] Where y(n)' is the current value output by the filter at time n, k3 is the filter coefficient, which is set to 3.82, k4 is the filter coefficient, which is set to -3.61, and x(n)' is the current value input to the system at time n.

[0039] The filtered phase voltage sampling values ​​and phase current sampling values ​​are subjected to Fourier transform to obtain the phase voltage phasor values ​​and the phase current phasor values. The inter-phase voltage phasor values ​​and the inter-phase current phasor values ​​are calculated based on the phase voltage phasor values ​​and the phase current phasor values. The positive-sequence voltage phasor value is calculated based on the phase voltage phasor value, and the positive-sequence current phasor value is calculated based on the phase current phasor value.

[0040] It should be noted that the supply and reception conditions of the power supply connected to the output protection installation location include, based on the positive-sequence voltage phasor and the positive-sequence current phasor, comparing the angle between the positive-sequence voltage phasor and the positive-sequence current phasor before the output fault with a judgment threshold value. The judgment threshold value is a preset angle value. If the angle is less than the judgment threshold value, the power supply connected to the protection installation location is judged to be the supply-end power supply. If the angle is greater than or equal to the judgment threshold value, the power supply connected to the protection installation location is judged to be the receiving-end power supply.

[0041] Obtain the angle between the positive sequence voltage phasor and the positive sequence current phasor before the fault, which can be expressed as:

[0042]

[0043] in, is the angle between the positive sequence voltage phasor and the positive sequence current phasor, is the positive sequence current phasor, is the positive sequence voltage phasor.

[0044] The method for determining the supply and reception status of the power supply connected to the protection installation location is expressed as follows:

[0045]

[0046] wherein, is an angle between the positive sequence voltage phasor and the positive sequence current phasor, θ c is a determination threshold.

[0047] If the angle between the positive sequence voltage phasor and the positive sequence current phasor is less than the determination threshold, it is considered that the power supply connected to the protection installation place is a supply end power supply, and if the angle between the positive sequence voltage phasor and the positive sequence current phasor is greater than or equal to the determination threshold, it is considered that the power supply connected to the protection installation place is a receiving end power supply.

[0048] When a line-to-line fault occurs, the low voltage ride through control system at the new energy station side generally uses negative sequence current suppression measurement, and the output positive sequence component of the fault current is dominant. As shown in the traditional new energy access system, Figure 2 When a line-to-line short-circuit fault occurs in the line area, if the new energy station continues to maintain the active power output mode, it will lead to the refusal of the traditional distance protection element based on power frequency quantities. When a reverse phase-to-phase short-circuit fault occurs at the N side outlet, the fault current is provided by the station side, and the N side protection will malfunction. Therefore, according to the real-time sampling data of the protection installation place, the supply and demand situation of the power supply is determined by the positive sequence voltage phasor and the positive sequence current phasor, and the compensation angle is calculated to improve the reliability of the protection.

[0049] It should be noted that according to the real-time sampling data of the protection installation place, the supply and demand situation of the power supply is determined by the positive sequence voltage phasor and the positive sequence current phasor, which solves the accuracy and real-time problem of power supply state recognition under the interference of high-frequency noise in traditional sampling data, realizes the determination of the supply and demand situation of the power supply under fault scenario, avoids the misjudgment caused by traditional methods, provides a key basis for the relay protection system, and significantly improves the adaptability and reliability of the distance protection under complex environment.

[0050] S2: dynamically adjusting the compensation angle based on the supply and demand situation of the power supply connected to the protection installation place.

[0051] Further, dynamically adjusting the compensation angle includes selecting different compensation strategies according to the supply and demand situation of the power supply connected to the protection installation place, determining the supply and demand situation based on the phase relationship between the positive sequence voltage phasor value and the positive sequence current phasor value before the fault, if it is determined that the power supply is a supply end power supply, a first angle compensation mode is adopted, and if it is determined that the power supply is a receiving end power supply, a second angle compensation mode is adopted.

[0052] It should be noted that the compensation angle is dynamically adjusted according to the supply and demand situation of the power supply connected to the protection installation place, and the first angle compensation mode is represented as:

[0053]

[0054] The second angle compensation method is expressed as:

[0055]

[0056] in, To dynamically adjust the compensation angle, c1 is a fixed compensation angle. is the angle between the positive sequence voltage phasor and the positive sequence current phasor, θ c To determine the threshold.

[0057] When it is determined that the power supply connected to the protection installation location is the supply end power supply, the first angle compensation method is used, otherwise the second angle compensation method is used. Figure 3 As shown in the figure, two typical scenarios are intuitively presented through complex plane coordinates. One is that the protection installation is connected to the supply power supply, and the other is that the protection installation is connected to the receiving power supply. Through the phasor geometric relationship, the role of the phase difference angle, the core parameter of the power property judgment, in the dynamic adjustment of the compensation angle is clarified, providing a theoretical basis for distance protection.

[0058] It should also be noted that by dynamically adjusting the compensation angle through real-time analysis of the phase difference between the positive-sequence voltage phasor value and the positive-sequence current phasor value, the problem of inaccurate distance protection range caused by differences in power supply characteristics in new energy access scenarios is solved, and the operation accuracy of the relay under complex fault conditions with phase offset and amplitude limitation is significantly improved.

[0059] S3: Determine the fault direction using the output results of the voltage change and current change after the fault.

[0060] Furthermore, the output results of the voltage change and current change after the fault include outputting the voltage change after the fault based on the sampling values ​​of the voltage at the protection installation at the current moment and the voltage at the protection installation at one cycle ahead, outputting the current change after the fault based on the sampling values ​​of the current at the protection installation at the current moment and the current at the protection installation at one cycle ahead, and determining the fault direction based on the voltage change after the fault and the current change after the fault.

[0061] The measured voltage change after a fault is expressed as:

[0062]

[0063] in, is the measured voltage change, n' is the time, is the voltage sampling value at the protection installation at time n', is the voltage sampling value at the protection installation point before one cycle, N is the number of sampling points per cycle, and m is the ABC three-phase in the power system, namely a, b, c or ab, bc, ca.

[0064] The measured current change after a fault is expressed as:

[0065]

[0066] in, To measure the current change, The current sampling value at the protection installation at time n' is: This is the current sampling value at the installation point of one cycle of wavefront protection.

[0067] It should be noted that determining the fault direction includes making a judgment based on the phase relationship between the measured voltage change and the measured current change after the fault. If the phases of the measured voltage change and the measured current change are consistent, it is determined to be a reverse fault. If the phases of the measured voltage change and the measured current change are opposite, it is determined to be a forward fault.

[0068] The fault direction is determined as:

[0069]

[0070] in, To measure the voltage change, To measure the change in current.

[0071] If the phase value of the measured voltage change and the measured current change is less than 0, it is determined to be a forward fault, such as Figure 4 As shown in the figure, the action principle during forward fault is demonstrated through the equivalent circuit model, the transmission path of the measured voltage and current changes at the protection installation is marked, and the same-direction characteristics during forward fault are demonstrated in the form of phasors. By superimposing the dynamic adjustment action area, the effect of the compensation angle on the expansion of the forward protection zone is intuitively presented. If the phase value of the measured voltage change and the measured current change is greater than or equal to 0, it is determined to be a reverse fault, such as Figure 5 As shown in the figure, the reverse phase relationship between the measured voltage change and the measured current change during a reverse fault is highlighted. By shrinking the action boundary, false operation due to faults outside the reverse zone is avoided. The impedance trajectory in the receiving power supply scenario and the safe distance of the action zone after adjustment are marked to verify the effectiveness of suppressing false operation due to reverse faults in the flexible DC system.

[0072] It should also be noted that by calculating the voltage and current changes after a fault in real time and analyzing the phase correlation between the two, a method for fault direction identification is performed to solve the problem of misjudgment caused by phase offset of traditional directional components due to the access of new energy power electronic equipment, significantly improving the accuracy and reliability of fault direction identification in complex fault scenarios, and providing key criteria for the correct operation of distance protection.

[0073] S4: Adjust the operating range of the distance relay according to the power supply and fault direction.

[0074] Furthermore, adjusting the operating range of the distance relay includes selecting a corresponding operating equation based on the determined fault direction. If it is determined to be a forward fault, the forward operating characteristic equation is adopted; if it is determined to be a reverse fault, the reverse operating characteristic equation is adopted. The operating characteristic equation is determined by the relationship between the operating voltage and the distance protection setting value.

[0075] It should be noted that the operating range of the distance relay is adjusted according to the determined fault direction. If it is determined to be a forward fault, the distance relay operating equation is expressed as:

[0076]

[0077] in, To dynamically adjust the compensation angle, is the positive sequence voltage phasor, is the operating voltage, To measure voltage phasors at the protection installation, To measure the current phasor at the protection installation, Z set It is the distance protection setting value.

[0078] If it is determined to be a reverse fault, the distance relay action equation is expressed as:

[0079]

[0080] in, To dynamically adjust the compensation angle, is the positive sequence voltage phasor, is the operating voltage.

[0081] The range of distance protection action after fault is as follows: Figure 6 As shown in the figure, the optimization effect of the dynamic compensation angle on the protection action characteristics is revealed by superimposing multiple parameters. The coordinate axis is marked with impedance amplitude and phase angle scale at the same time, which is convenient for direct correspondence with actual system parameters.

[0082] It should also be noted that the dynamic compensation angle and the adaptive action equation adjustment mechanism of the fault direction can solve the problem of false operation caused by the fixed range of traditional distance protection when the system impedance characteristics change due to the access of new energy. This can achieve accurate distance protection under different power supply characteristics and fault directions, provide key technical support for the safe operation of the system, and significantly improve the adaptability of the protection device to complex power grid faults.

[0083] Example 2, reference Figure 7-11 , which is an embodiment of the present invention, provides a distance protection method based on transient and steady-state feature fusion criteria. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0084] First, a BC phase-to-phase fault occurred outside the reverse zone on the system side of the 220kV new energy transmission line. During the fault, the voltage and current waveforms recorded at the system side protection installation were as follows: Figure 7 As shown in , the fault phase voltage is significantly reduced, the fault phase current amplitude is increased, and non-periodic components appear, which is consistent with the characteristics of phase-to-phase fault. Figure 8 As shown, the positive sequence current measured at the protection installation before the fault is Leading positive sequence voltage The angle is 193°, indicating that the system on this side presents the receiving end characteristic, that is, absorbing active power. Further calculation yields the compensation angle Used for subsequent direction determination and distance protection setting. After a fault occurs, the directional element is used to determine the fault direction. The directional element is based on the voltage change measured after the fault. Measuring current change Calculate the fault direction discriminant. Figure 9 As shown, in the initial stage after the fault, Δu m (n') and Δi m If the product of (n') is greater than 0, it is determined to be a reverse fault. Since the fault is outside the reverse zone and the system side is the receiving power supply, in order to prevent the distance relay from malfunctioning, its operating range needs to be adjusted. The adjustment result is as follows Figure 10 As shown in the figure, after adjusting the upper and lower limits of its operating range by 28°, the distance relay will reliably not operate during the BC phase-to-phase fault outside the reverse zone, effectively avoiding false protection operation and ensuring stable system operation.

[0085] Secondly, the system adopts a semi-physical simulation model, and its structure is as follows Figure 11 The simulation parameters are shown in Table 1. The distance protection setting is set to 80% of the full-length line impedance, and multi-type fault simulations are performed at four preset fault points: F1, F2, F3, and F4.

[0086] Table 1 Simulation parameters

[0087]

[0088] The traditional distance protection device, the distance protection device with fixed angle compensation, and the distance protection device based on the dynamic angle compensation of the present invention are connected to the simulation system at positions P1 and P2, respectively. Various types of faults at different positions are simulated, and different control strategies are used. The action results are shown in Table 2.

[0089] Table 2 Action result table

[0090]

[0091]

[0092] As shown in Table 2, the correct operation rate of traditional distance protection devices is low. The distance protection device with fixed angle compensation is a significant improvement over the traditional distance protection device, but it still does not reach a very high level. The protection device of the present invention has a correct operation rate of 100%, which is significantly better than the traditional distance protection device and the distance protection device with fixed angle compensation in terms of performance. It solves the problem of incorrect operation of phase-to-phase fault distance protection caused by the integration of new energy sources and is a more reliable and advanced protection solution.

[0093] Example 3 is an embodiment of the present invention, which provides a distance protection system based on transient and steady-state feature fusion criteria, including a state perception module, a dynamic compensation decision module, and a fault response and protection module.

[0094] Among them, the state perception module is used to collect electrical quantity data at the protection installation in real time. According to the acquired phase voltage and phase current sampling values, after noise elimination filtering and phasor conversion processing, the key phasors of phase voltage phasor, phase-to-phase voltage phasor, phase-to-phase current phasor, positive-sequence voltage phasor and positive-sequence current phasor are output. The angle between the positive-sequence voltage phasor value and the positive-sequence current phasor value is used to determine the supply and reception status of the power supply connected to the protection installation.

[0095] Among them, the dynamic compensation decision module is used to perform dynamic adjustment of protection parameters based on the supply and reception conditions of the power supply connected to the protection installation location determined by the state perception module, and select the corresponding compensation strategy according to the supply and reception conditions of the power supply. If it is determined to be the supply-end power supply, the first angle compensation method is adopted; if it is determined to be the receiving-end power supply, the second angle compensation method is adopted.

[0096] Among them, the fault response and protection module is used to determine the fault direction by measuring the phase relationship between the voltage change and the current change after the output fault. If the phasor directions of the two are consistent, it is determined to be a reverse fault. Otherwise, if the phasor directions of the two are opposite, it is determined to be a forward fault. The determined fault direction is used to adjust the action range of the distance relay and select the corresponding distance relay action equation. The forward action characteristic equation is used for forward faults and the reverse action characteristic equation is used for reverse faults.

Claims

1. A distance protection method based on transient and steady state feature fusion criteria, characterized in that: include: Output various types of phasor values ​​based on the data sampling values ​​at the protection installation location, and output the supply and reception status of the power supply connected to the protection installation location according to the angle between the positive sequence voltage and the positive sequence current before the fault; Dynamically adjust the compensation angle based on the power supply and reception conditions of the protection installation location; Determine the fault direction using the output results of voltage change and current change after the fault; Adjust the operating range of the distance relay according to the power supply and fault direction; Outputting various types of phasor values ​​includes filtering and Fourier transforming the sampled data to output phase voltage phasor values ​​and phase current phasor values; The various types of phasor values ​​include phase voltage phasor, phase current phasor, inter-phase voltage phasor, inter-phase current phasor, positive sequence voltage phasor and positive sequence current phasor.

2. The distance protection method based on transient and steady state feature fusion criteria according to claim 1, characterized in that: The output of various types of phasor values ​​includes: The phase voltage and phase current sampling values ​​at the protection installation are filtered, the phase voltage and phase current are processed by a differential filter, and the filtered sampling values ​​are Fourier transformed to output the phase voltage phasor value and the phase current phasor value.

3. The distance protection method based on transient and steady state feature fusion criteria according to claim 1, characterized in that: The supply and reception conditions of the power supply connected to the output protection installation location include: Based on the positive-sequence voltage phasor and the positive-sequence current phasor, the angle between the positive-sequence voltage phasor and the positive-sequence current phasor before the output fault is compared with a judgment threshold value, where the judgment threshold value is a preset angle value. If the angle is less than the judgment threshold value, it is determined that the power supply connected to the protection installation location is a supply-end power supply. If the angle is greater than or equal to the judgment threshold value, it is determined that the power supply connected to the protection installation location is a receiving-end power supply.

4. The distance protection method based on transient and steady state feature fusion criteria according to claim 1, characterized in that: The dynamic adjustment of the compensation angle includes: Different compensation strategies are selected according to the supply and reception conditions of the power supply connected to the protection installation location. The supply and reception conditions are determined based on the phase relationship between the positive-sequence voltage phasor value and the positive-sequence current phasor value before the fault. If it is determined to be the supply-end power supply, the first angle compensation method is adopted. If it is determined to be the receiving-end power supply, the second angle compensation method is adopted.

5. The distance protection method based on transient and steady state feature fusion criteria according to claim 1, characterized in that: The output results of the voltage change and current change after the fault include: The post-fault voltage change is output based on the sampling values ​​of the voltage at the protection installation at the current moment and the voltage at the protection installation at one cycle ahead. The post-fault current change is output based on the sampling values ​​of the current at the protection installation at the current moment and the current at the protection installation at one cycle ahead. The fault direction is determined based on the post-fault voltage change and the post-fault current change.

6. The distance protection method based on transient and steady state feature fusion criteria according to claim 5, characterized in that: Determining the fault direction includes: The fault is judged based on the phase relationship between the measured voltage change and the measured current change after the fault. If the phases of the measured voltage change and the measured current change are consistent, it is judged as a reverse fault. If the phases of the measured voltage change and the measured current change are opposite, it is judged as a forward fault.

7. The distance protection method based on transient and steady state feature fusion criteria according to claim 1, characterized in that: The operating range of the distance adjustment relay includes: The corresponding action equation is selected based on the determined fault direction. If it is determined to be a forward fault, the forward action characteristic equation is adopted. If it is determined to be a reverse fault, the reverse action characteristic equation is adopted. The action characteristic equation is determined by the relationship between the operating voltage and the distance protection setting value.

8. A distance protection system based on a transient and steady-state feature fusion criterion, employing a distance protection method based on a transient and steady-state feature fusion criterion according to any one of claims 1 to 7, characterized in that: Including state perception module, dynamic compensation decision module, fault response and protection module; The state perception module is used to collect electrical quantity data at the protection installation in real time, and output the key phasors of phase voltage phasor, phase current phasor, phase-to-phase voltage phasor, phase-to-phase current phasor, positive-sequence voltage phasor and positive-sequence current phasor based on the obtained phase voltage and phase current sampling values ​​after noise elimination filtering and phasor conversion processing. The angle between the positive-sequence voltage phasor value and the positive-sequence current phasor value is used to determine the supply and reception status of the power supply connected to the protection installation; The dynamic compensation decision module is used to dynamically adjust the protection parameters based on the supply and reception conditions of the power supply connected to the protection installation location determined by the state sensing module, and select a corresponding compensation strategy according to the supply and reception conditions of the power supply. If it is determined to be a supply-end power supply, a first angle compensation method is adopted; if it is determined to be a receiving-end power supply, a second angle compensation method is adopted; The fault response and protection module is used to determine the fault direction by measuring the phase relationship between the voltage change and the current change after the output fault. If the phasor directions of the two are consistent, it is determined to be a reverse fault; otherwise, if the phasor directions of the two are opposite, it is determined to be a forward fault. The determined fault direction is used to adjust the action range of the distance relay and select the corresponding distance relay action equation. The forward action characteristic equation is used in the case of a forward fault, and the reverse action characteristic equation is used in the case of a reverse fault.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the processor implements the steps of a distance protection method based on transient state feature fusion criterion according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a distance protection method based on transient state feature fusion criterion according to any one of claims 1 to 7 are implemented.

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