CN113030635A - Non-contact type traveling wave fault location method and device - Google Patents
Non-contact type traveling wave fault location method and device Download PDFInfo
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- CN113030635A CN113030635A CN202110174546.9A CN202110174546A CN113030635A CN 113030635 A CN113030635 A CN 113030635A CN 202110174546 A CN202110174546 A CN 202110174546A CN 113030635 A CN113030635 A CN 113030635A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- H—ELECTRICITY
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- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
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- H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
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- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The application relates to a non-contact traveling wave fault location method, which is used for solving the problem of detecting the fault of a power transmission line under the condition of not contacting primary equipment of a power system and effectively avoiding the fault and hidden danger of the equipment caused by the fact that a monitoring device contacts the primary equipment of the power transmission line. The method in the embodiment of the application comprises the following steps: receiving a space magnetic field signal of the power transmission line through a magnetic field sensor; comparing the space magnetic field signal with a first magnetic field signal, wherein the first magnetic field signal is a preset threshold range when the power transmission line normally operates; determining whether to trigger the recording of the fault traveling wave according to the comparison result of the space magnetic field signal and the first magnetic field signal; if the fault traveling wave recording is triggered, recording a first trigger time, a second trigger time, a third trigger time and a fourth trigger time according to the fault traveling wave recording result; and calculating a fault distance according to the first trigger time, the second trigger time, the third trigger time and the fourth trigger time, wherein the fault distance is the distance from a fault point of the power transmission line to a monitoring point.
Description
Technical Field
The application relates to the field of fault maintenance, in particular to a non-contact traveling wave fault location method and a non-contact traveling wave fault location device.
Background
With the continuous expansion of the power grid scale and the continuous improvement of the transmission power and the voltage grade of the power transmission line, the requirement of users on the safety of the power grid is higher and higher, so that the accurate fault location becomes the important guarantee of rapidly removing faults and improving the transient stability of the system, and the detection accuracy of the traveling wave signal directly influences the accuracy of the traveling wave location and the reliability of the traveling wave protection.
At present, the fault location technology of the traveling wave method becomes the mainstream technology of the rapid fault location of the power transmission line, and in the fault location technology of the traveling wave method, the traveling wave signal of the power transmission line is detected by adopting the principle of a voltage transformer or a current transformer, which comprises the following steps: 1) the voltage traveling wave signal is generally extracted from the secondary side of the voltage transformer, and a voltage traveling wave sensor can be sleeved on the ground wire of the CVT to detect the voltage traveling wave signal; 2) the current traveling wave signal can be directly extracted from the secondary side of a current transformer (rogowski coil current transformer).
No matter in the prior art, no matter a voltage transformer or a current transformer principle is adopted to detect a transmission line traveling wave signal, the transmission line traveling wave signal is required to be in direct contact with primary equipment of a transmission line, construction inconvenience is caused, interference of the primary equipment is easily caused, certain hidden danger is caused to safe operation of the transmission line, and application requirements of a traveling wave technology are difficult to meet. Meanwhile, in the existing traveling wave method fault location technology, a power-taking CT is generally adopted to take power on a power transmission line by an electromagnetic induction principle to maintain the operation of the traveling wave distance measurement device, but when the load current of the power transmission line is small, such as a low-load hot standby line and a terminal line, the power-taking CT cannot obtain a stable power supply, cannot ensure the stable operation of the traveling wave distance measurement device, and cannot ensure the accuracy of a detection result.
Disclosure of Invention
In order to solve the problems in the prior art, the non-contact traveling wave fault location method solves the problem of detecting the fault of the power transmission line under the condition of not contacting primary equipment of the power system, and effectively avoids the faults and hidden dangers of the equipment caused by the fact that a monitoring device contacts the primary equipment of the power transmission line.
The non-contact traveling wave fault location method provided by the first aspect of the application comprises the following steps:
receiving a space magnetic field signal of the power transmission line through a magnetic field sensor;
comparing the space magnetic field signal with a first magnetic field signal, wherein the first magnetic field signal is a preset threshold range when the power transmission line normally operates;
determining whether to trigger the recording of the fault traveling wave according to the comparison result of the space magnetic field signal and the first magnetic field signal;
if the fault traveling wave recording is triggered, recording a first trigger time, a second trigger time, a third trigger time and a fourth trigger time according to the fault traveling wave recording result;
and calculating a fault distance according to the first trigger time, the second trigger time, the third trigger time and the fourth trigger time, wherein the fault distance is the distance from a fault point of the power transmission line to a monitoring point.
In one embodiment of the present application, the method comprises:
the magnetic field sensor includes: a shield, a coil, and a magnetic core;
the coil is tightly wound on the surface of the magnetic core;
the appearance of magnetic core is the cylinder, and the preparation material of magnetic core includes: soft magnetic ferrite, amorphous alloy or silicon steel sheet;
the shielding case is used for preventing the magnetic field inductor from being interfered by the external environment.
In one embodiment of the present application, the method comprises:
the sum of the diameter lengths of the wires of the coils is less than the length of the magnetic core; the number of turns of the coil is less than 5000 turns.
In one embodiment of the present application, the method comprises:
the spatial magnetic field signal includes: traveling wave current, magnetic induction and induced electromotive force;
the traveling wave current generates a magnetic field ring around the transmission line, and the magnetic field ring is perpendicular to the propagation direction of the traveling wave current;
the magnetic induction intensity is the magnetic flux density of the magnetic field ring;
the induced electromotive force is generated by the magnetic field sensor induced magnetic field loop.
In an embodiment of the present application, if the spatial magnetic field signal is magnetic induction, receiving the spatial magnetic field signal of the power transmission line through the magnetic field sensor includes:
obtaining magnetic induction intensity according to the traveling wave current and the induction distance, wherein the mathematical expression of the magnetic induction intensity is formula A):
wherein B is magnetic induction, mu0The magnetic field sensor is a vacuum magnetic conductivity, I is a traveling wave current, pi is a circumferential ratio, l is an induction distance, and the induction distance is the distance from any point in the magnetic field sensor to a power transmission line.
In an embodiment of the present application, if the spatial magnetic field signal is induced electromotive force, receiving the spatial magnetic field signal of the power transmission line through the magnetic field sensor includes:
calculating induced electromotive force according to the magnetic induction intensity and the traveling wave current, wherein the mathematical expression of the induced electromotive force is a formula B):
wherein E is induced electromotive force, n is the number of turns of the magnetic field sensor coil, E is the rate of change of magnetic flux, μ0For vacuum permeability,. pi.is the circumferential ratio,. is(t) is a function of the time variation of the traveling wave current in the induction period, t is induction time, l is induction distance, l is1And l2The distances between the near side and the far side of the magnetic field sensor and the power transmission line are respectively.
In one embodiment of the present application, the method comprises:
the comparison result of the spatial magnetic field signal and the second magnetic field signal comprises the following steps:
the comparison result of the traveling wave current, the comparison result of the magnetic induction intensity or the comparison result of the induced electromotive force;
determining whether to trigger the recording of the fault traveling wave according to the comparison result of the space magnetic field signal and the first magnetic field signal, wherein the determining step comprises the following steps:
and if the space magnetic field signal is not within the threshold range set by the first magnetic field signal, a fault traveling wave signal exists in the power transmission line, and the fault traveling wave is triggered to be recorded.
In one embodiment of the present application, the method comprises:
the monitoring points comprise: a first monitoring point and a second monitoring point;
recording a first trigger time, a second trigger time, a third trigger time and a fourth trigger time according to a recording result of the fault traveling wave, and the method comprises the following steps:
determining the waveform characteristics of the fault traveling wave signal, wherein the waveform characteristics are that the time difference from the wave trough to the wave crest and the time difference from the wave crest to the wave trough are minimum and the amplitude is maximum;
extracting a waveform with waveform characteristics;
according to the extraction result, the waveform with the waveform characteristics recorded for the first time by the first monitoring point is a first waveform, the first waveform corresponds to the fault traveling wave signal and reaches the first monitoring point from the fault point for the first time, and the moment corresponding to the peak value of the first waveform is recorded as a first trigger moment;
according to the extraction result, the waveform with the waveform characteristics recorded for the first time by the second monitoring point is a second waveform, the second waveform corresponds to the fault traveling wave signal and reaches the second monitoring point from the fault point for the first time, and the moment corresponding to the peak value of the second waveform is recorded as a second trigger moment;
according to the extraction result, the waveform with the waveform characteristics recorded by the first monitoring point for the second time is a third waveform, the fault traveling wave signal corresponding to the third waveform starts from the first monitoring point and reaches the first monitoring point for the second time after being reflected by the first transformer substation, and the time corresponding to the peak value of the third waveform is recorded as a third trigger time;
according to the extraction result, the waveform with the waveform characteristics recorded for the second time by the second monitoring point is a fourth waveform, the fault traveling wave signal corresponding to the fourth waveform starts from the second monitoring point and reaches the second monitoring point for the second time after being reflected by the second transformer substation, and the moment corresponding to the peak value of the fourth waveform is recorded as a fourth trigger moment;
the first transformer substation and the second transformer substation are power systems at two ends of the power transmission line and are used for transmitting fault traveling wave signals.
In one embodiment of the present application, the method comprises:
calculating the transmission speed of the fault traveling wave signal according to the first triggering time, the third triggering time and the distance from the first monitoring point to the first substation, wherein the mathematical expression of the transmission speed of the fault traveling wave signal is formula C):
v is the transmission speed of the fault traveling wave signal, L1 is the distance from the first monitoring point to the first substation, t1 is the first triggering time, and t3 is the third triggering time.
In one embodiment of the present application, calculating the fault distance according to the first trigger time, the second trigger time, the third trigger time, and the fourth trigger time includes:
calculating the fault distance by formula D), the mathematical expression of the fault distance being formula D):
wherein x1 is the distance from the fault point to the first monitoring point, x2 is the distance from the fault point to the second monitoring point, v is the transmission speed of the fault traveling wave signal, t1 is the first triggering time, t2 is the second triggering time, t3 is the third triggering time, t4 is the fourth triggering time, and L is the distance from the first monitoring point to the second monitoring point;
and feeding back the calculation result of the fault distance and executing an alarm process.
A second aspect of the embodiments of the present application provides a non-contact traveling wave fault location apparatus, including:
the magnetic field sensor is used for receiving a space magnetic field signal of the power transmission line;
the monitoring and recording device is used for monitoring and recording the waveform of the fault traveling wave signal and recording a first trigger time, a second trigger time, a third trigger time and a fourth trigger time;
the distance measurement analysis device is used for calculating a fault distance;
the information feedback device is used for feeding back the calculation result of the fault distance and executing an alarm process;
and the power supply device is powered by adopting a storage battery and a photovoltaic panel and is used for maintaining the stable use of the non-contact traveling wave fault location device.
According to the technical scheme, the embodiment of the application has the following beneficial effects:
the embodiment of the application determines the existence of a fault traveling wave signal by designing a non-contact magnetic field sensor, detects the space magnetic field signal, and determines the existence of the fault traveling wave signal by comparing the space magnetic field signal with a preset threshold range (namely, a first magnetic field signal) when a power transmission line normally runs, thereby starting a fault traveling wave recording function, recording four trigger moments when the fault traveling wave passes through a monitoring point according to the recorded result of the fault traveling wave, calculating the fault distance of the fault traveling wave signal, solving the problem that the traditional online fault distance measuring device can monitor the fault of the power transmission line and measure the fault distance only by contacting with primary equipment of a power system, and effectively avoiding faults and hidden dangers caused to the primary equipment by contacting with the primary equipment of the power transmission line. Meanwhile, the device provided by the embodiment of the application adopts the storage battery and the photovoltaic panel to supply power, so that the problem of power taking of the traditional online fault distance measuring device in a high-voltage power transmission line is solved, and the sustainability and the stability of the operation of the device are ensured.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The foregoing and other objects, features and advantages of the application will be apparent from the following more particular descriptions of exemplary embodiments of the application, as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the application.
FIG. 1 is a schematic flow chart of an embodiment of a non-contact traveling wave fault location method according to an embodiment of the present application;
FIG. 2 is a schematic flow chart of an embodiment of a non-contact traveling wave fault location method according to an embodiment of the present application;
FIG. 3 is a schematic flow chart of an embodiment of a non-contact traveling wave fault location method according to an embodiment of the present application;
FIG. 4 is a schematic view of a scenario of a non-contact traveling wave fault location method in an embodiment of the present application;
fig. 5 is a schematic wave head characteristic diagram of a non-contact traveling wave fault location method in an embodiment of the present application.
Detailed Description
Preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
It should be understood that although the terms "first," "second," "third," etc. may be used herein to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present application. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.
Example one
Referring to fig. 1, a first embodiment of a non-contact traveling wave fault location method in the embodiment of the present application includes:
101. receiving a space magnetic field signal of the power transmission line through a magnetic field sensor;
when current flows through the power transmission line, any conducting wire passing through the current can generate a magnetic field around the conducting wire according to the current magnetic effect, and a space magnetic field can also be generated around the power transmission line.
The spatial magnetic field signal is a combination of characteristic physical quantity data of the spatial magnetic field, and reflects the property and the change condition of the spatial magnetic field.
The magnetic field sensor is close to the power transmission line to receive characteristic physical quantity data of the space magnetic field and detect the property and the change condition of the space magnetic field.
In a calculation manner of the induced electromotive force, the induced electromotive force is calculated according to the magnetic induction intensity and the traveling wave current, and a mathematical expression of the induced electromotive force is a formula B):
wherein E is the induced electromotive force, n is the number of turns of the magnetic field sensor coil, E is a rate of change in magnetic flux, μ0For vacuum permeability,. pi.is the circumferential ratio,. is(t) is a function of the time variation of the traveling wave current in the induction period, t is induction time, l is the induction distance, l is1And l2The distances between the near edge and the far edge of the magnetic field sensor and the power transmission line are respectively.
It will be appreciated that in practical applications, other ways of detecting the nature of the spatial magnetic field and its variation are possible, and the above detection ways are merely exemplary and should not be taken as the only limitation for detecting the spatial magnetic field.
When the power transmission line has a fault, a fault traveling wave is generated at a fault point, the voltage and the current of the power transmission line can be changed in the transmission process of the traveling wave, and the change condition of the current in the line can be reflected in real time by an electromagnetic field detected around the line, so that various characteristic information of a fault traveling wave signal can be obtained by detecting a space magnetic field signal.
102. Comparing the spatial magnetic field signal with the first magnetic field signal;
in the embodiment of the application, a threshold range of the spatial magnetic field signal when the power transmission line normally operates is preset, that is, the first magnetic field signal, and when the comparison operation is performed, the magnetic field sensor collects characteristic physical quantity data of the spatial magnetic field, that is, the spatial magnetic field signal, and the characteristic physical quantity threshold range of the first magnetic field signal is compared in a one-to-one correspondence or one-to-one correspondence manner, that is, the comparison is performed based on the same characteristic physical quantity.
103. Determining whether to trigger the recording of the fault traveling wave according to the comparison result of the space magnetic field signal and the first magnetic field signal;
if the comparison result shows that the comparison result is within the threshold value range of normal operation, the fault traveling wave recording is not triggered; and if the comparison result shows that the comparison result is outside the threshold range of normal operation, triggering the recording of the fault traveling wave.
104. If the fault traveling wave recording is triggered, recording a first trigger time, a second trigger time, a third trigger time and a fourth trigger time according to the fault traveling wave recording result;
after the fault traveling wave recording is started, the electric wave signals transmitted in the line are recorded and stored, and the recorded waveforms cover the waveforms of the fault traveling wave signals.
The first trigger time, the second trigger time, the third trigger time and the fourth trigger time are respectively corresponding times when the waveform of the fault traveling wave signal appears.
105. And calculating the fault distance according to the first trigger time, the second trigger time, the third trigger time and the fourth trigger time.
The fault distance is the distance from the fault point of the power transmission line to the monitoring point.
According to the technical scheme, the non-contact magnetic field sensor is designed, the space magnetic field signal is detected, the existence of the fault traveling wave signal is determined by comparing the space magnetic field signal with a preset threshold range (namely, the first magnetic field signal) when the power transmission line normally runs, so that the fault traveling wave recording function is started, four trigger moments when the fault traveling wave passes through monitoring points are recorded according to the recorded fault traveling wave result, the fault distance of the fault traveling wave signal is calculated, the problems that the traditional online fault distance measuring device can monitor the fault of the power transmission line and measure the fault distance only through one-time equipment contact with the power system are solved, and faults and hidden dangers caused to one-time equipment due to the fact that the monitoring device contacts the one-time equipment of the power transmission line.
For convenience of understanding, an application embodiment of the non-contact traveling wave fault location method is provided below for explanation, and referring to fig. 2, a second embodiment of the non-contact traveling wave fault location method in the application embodiment includes:
in the embodiment of the application, the fault distance measurement principle is realized by adopting a double-end traveling wave fault positioning principle, so that the monitoring points comprise a first monitoring point and a second monitoring point.
201. Receiving a space magnetic field signal of the power transmission line through a magnetic field sensor;
in the embodiment of the application, the magnetic field sensor consists of a shielding case, a coil and a magnetic core from outside to inside. The magnetic field sensor has the characteristics of low pass frequency and high stop frequency, namely, the higher the traveling wave current frequency is, the higher the impedance of the magnetic field sensor is, and the impedance calculation formula is as follows:
in the formula: r is the resistance of the sensor coil in unit length, s is the length of the sensor coil, w is the frequency of the current of the travelling wave of the transmission line, and l is the inductance of the sensor
However, in the embodiment of the present application, the traveling wave fault current generated at the fault point is a high frequency, and a magnetic field sensor is used to detect a spatial magnetic field signal change caused by the fault traveling wave current, so that the used magnetic field sensor needs to have a high frequency passing characteristic, and in order to reduce the impedance of the magnetic field sensor, the number of turns of a magnetic field sensor coil should not be too large to cause signal distortion, so that the magnetic core should be selected from materials such as soft magnetic ferrite, amorphous alloy, silicon steel sheet and the like during the design of the magnetic field sensor, the shape of the magnetic core should be a cylinder or a square cylinder, and the length of the iron core should not be less than the length of; the number of turns of the magnetic field sensor coil should not be greater than 5000 turns. In order to ensure that the magnetic field sensor is not interfered by the external environment, a shielding measure is taken for the magnetic field sensor, and a shielding cover is added outside the magnetic field sensor.
Meanwhile, as the space magnetic field signal is detected without contacting with the power transmission line in the embodiment, the storage battery and the photovoltaic panel are adopted for supplying power.
202. Comparing the spatial magnetic field signal with the first magnetic field signal;
in the embodiment of the present application, the content of step 202 is the same as the content of step 102 in the first embodiment, and is not described herein again.
203. Determining whether to trigger the recording of the fault traveling wave according to the comparison result of the space magnetic field signal and the first magnetic field signal;
in the embodiment of the application, when the power transmission line normally works, the value of a space magnetic field signal around the power transmission line is x, and a magnetic field threshold value preset by a system is also x, and at this time, the triggering condition cannot be met, and the wave recording device does not work; when the transmission line is in fault, fault traveling wave current is generated at a fault point, the traveling wave current generates a new magnetic field z, when the new magnetic field flows to a detection point along with the traveling wave current, z and x are superposed to generate a new magnetic field y, y is equal to z plus x, so that y is larger than a preset magnetic field threshold value x, a trigger condition is reached, and the wave recording device receives a signal for starting wave recording and starts to work for wave recording.
204. If the fault traveling wave recording is triggered, recording a first trigger time, a second trigger time, a third trigger time and a fourth trigger time according to the fault traveling wave recording result;
in the embodiment of the present application, according to the obvious difference between the fault traveling wave current, the fault traveling wave voltage, and the noise signal, as shown in fig. 5, the time difference between the wave trough and the wave crest of the pulse signal and the time difference between the wave crest and the wave trough of the pulse signal are two minimum values, and the amplitude value is the maximum value, then 50% of the amplitude value of the wave crest can be defined according to two characteristics of the wave head, that is, the time difference between a and b is tp, that is, the wave head of the pulse signal reflected from the fault point can be identified by the wave crest with the minimum tp and the maximum amplitude value, and then the time when the fault signal reaches the detection point can be automatically recorded in sequence, and specifically, how many times.
Analyzing the waveform result obtained by recording the fault traveling wave, determining the waveform characteristics of the fault traveling wave signal in the fault traveling wave recording result, wherein the waveform characteristics are that the time difference from the trough to the wave peak and the time difference from the wave peak to the wave peak are the minimum and the amplitude is the maximum, filtering out the waveforms which do not accord with the characteristics, and the rest is the waveform corresponding to the fault traveling wave.
It will be appreciated that in practical applications, the waveform characteristics of the fault traveling wave may be defined in other ways, and the above fault traveling wave waveform characteristics are merely exemplary and should not be taken as the only definition of the fault traveling wave waveform characteristics.
And assuming that the propagation track of one end of the fault traveling wave signal starts from a fault point, propagates to the monitoring point for the first time, then continues to propagate along the current direction to reach the transformer substation, and then reaches the monitoring point for the second time after being reflected by the transformer substation.
The reflection occurs because the node readjusts and distributes the current, voltage and energy of the fault traveling wave signal, so that the reflection phenomenon of the fault traveling wave occurs at the node.
The node is a place where the uniformity in the line begins to be damaged, and in this embodiment, the substation, the monitoring point, and the fault point can all be regarded as nodes.
The first trigger time: according to the extraction result, the waveform with the waveform characteristics recorded for the first time by the first monitoring point is a first waveform, the first waveform corresponds to the fault traveling wave signal and reaches the first monitoring point from the fault point for the first time, and the time corresponding to the peak value of the first waveform is recorded as a first trigger time;
the second trigger time is: according to the extraction result, the waveform with the waveform characteristics recorded for the first time by the second monitoring point is a second waveform, the second waveform corresponds to the fault traveling wave signal and reaches the second monitoring point from the fault point for the first time, and the time corresponding to the peak value of the second waveform is recorded as a second trigger time;
the third trigger time: according to the extraction result, the waveform with the waveform characteristics recorded by the first monitoring point for the second time is a third waveform, the fault traveling wave signal corresponding to the third waveform starts from the first monitoring point and reaches the first monitoring point for the second time after being reflected by the first transformer substation, and the time corresponding to the peak value of the third waveform is recorded as a third trigger time;
the fourth trigger time: according to the extraction result, the waveform with the waveform characteristics recorded for the second time by the second monitoring point is a fourth waveform, the fault traveling wave signal corresponding to the fourth waveform starts from the second monitoring point and reaches the second monitoring point for the second time after being reflected by the second transformer substation, and the moment corresponding to the peak value of the fourth waveform is recorded as a fourth trigger moment;
205. calculating the speed of the fault traveling wave according to the first triggering time, the third triggering time and the distance from the first monitoring point to the first transformer substation;
as can be seen from the propagation trace of the fault traveling wave, the fault traveling wave signal arrives at the first monitoring point again from the first monitoring point at the time t1 to the time t3, and the fault traveling wave signal propagates the distance from the first monitoring point to the first substation two times in the period of time, so that the mathematical expression of the transmission speed of the fault traveling wave signal can be defined as formula C):
v is the transmission speed of the fault traveling wave signal, L1 is the distance from the first monitoring point to the first substation, t1 is the first trigger time, and t3 is the third trigger time.
Similarly, the fault traveling wave speed passing through the second monitoring point can be calculated according to the second triggering time, the fourth triggering time and the distance from the second monitoring point to the second transformer substation, and the calculation result is consistent with the fault traveling wave speed.
206. And calculating the fault distance of the fault traveling wave signal according to the transmission speed of the fault traveling wave signal, the first trigger time and the second trigger time.
As illustrated in fig. 4, the fault distance is calculated by formula D):
wherein x1 is the distance from the fault point to the first monitoring point M, x2 is the distance from the fault point N to the second monitoring point, v is the transmission speed of the fault traveling wave signal, t1 is the first trigger time, t2 is the second trigger time, t3 is the third trigger time, t4 is the fourth trigger time, and L is the distance from the first monitoring point to the second monitoring point;
according to the expression, v (t2-t1) can be understood as the distance from the fault point to the second monitoring point is more than the distance from the fault point to the first monitoring point, L is the distance from the first monitoring point to the second monitoring point, and the distance from the two fault points to the first monitoring point can be calculated by subtracting the more distances;
similarly, in the second formula, L is the distance from the first monitoring point to the second monitoring point, and the distance between the two sections of fault points and the second monitoring point can be calculated by adding the excess distance.
The embodiment of the application determines the existence of a fault traveling wave signal by designing a non-contact magnetic field sensor, detects the space magnetic field signal, and determines the existence of the fault traveling wave signal by comparing the space magnetic field signal with a preset threshold range (namely, a first magnetic field signal) when a power transmission line normally runs, thereby starting the fault traveling wave recording function, and adopts a double-end traveling wave fault positioning principle, two monitoring points are utilized, four triggering moments of the fault traveling wave passing through the monitoring points are recorded according to the recording result of the fault traveling wave, and the fault distance of the fault traveling wave signal is calculated. Furthermore, in the embodiment of the application, a specially-made magnetic field sensor capable of passing high frequency is adopted, so that the magnetic field sensor can detect the magnetic field change caused by the fault traveling wave current more truly.
For convenience of understanding, an application embodiment of the non-contact traveling wave fault location method is provided below for explanation, and referring to fig. 3, a third embodiment of the non-contact traveling wave fault location method in the embodiment of the present application includes:
in this embodiment of the application, the method for triggering the recording of the traveling wave may adopt a magnetic induction intensity as a comparison between a spatial magnetic field signal and a preset magnetic induction intensity threshold of the first magnetic field signal.
301. Receiving a space magnetic field signal of the power transmission line through a magnetic field sensor;
in this embodiment, the spatial magnetic field signal is magnetic induction intensity, the magnetic induction intensity is dynamically changed according to traveling wave current in the power transmission line and the distance between the magnetic field sensor and the power transmission line, and a mathematical expression of the magnetic induction intensity is as follows: formula a):
wherein B is the magnetic induction, mu0And the induction distance is the distance from any point in the magnetic field sensor to the power transmission line.
302. Comparing the space magnetic field signal with a preset magnetic field threshold, and triggering the recording of the fault traveling wave if the space magnetic field signal reaches the preset magnetic field threshold;
the comparison result shows that the magnetic induction intensity is within the threshold value range of normal operation, and the fault traveling wave recording is not triggered; and if the comparison result shows that the magnetic induction intensity is out of the threshold range of normal operation, triggering the recording of the fault traveling wave.
303. Determining the triggering time when the fault signal reaches the detection point according to the recording result of the fault traveling wave;
in this embodiment of the present application, there is only one detection point, and there are two trigger times recorded, including:
time T1 at which the spatial magnetic field signal first reaches the magnetic field sensor;
the second reflection of the spatial magnetic field signal from the point of failure back to the magnetic field sensor is at time T2.
304. And calculating the fault distance according to the triggering moment.
In the embodiment of the application, the fault distance X is calculated according to the theoretical transmission speeds V, T1 and T2 of the traveling wave. As shown in the following formula:
in the embodiment of the application, adopt single-ended travelling wave fault location principle to carry out the range finding, need not to carry out accurate time to, required range unit is few simultaneously.
The embodiment of the present application further provides a non-contact traveling wave fault location device, including:
the magnetic field sensor is used for receiving a space magnetic field signal of the power transmission line;
the monitoring and wave recording device is used for monitoring and recording the waveform of the fault traveling wave signal and recording the first trigger time, the second trigger time, the third trigger time and the fourth trigger time;
the distance measurement analysis device is used for calculating the fault distance;
the information feedback device is used for feeding back the calculation result of the fault distance and executing an alarm process;
and the power supply device supplies power in the form of a storage battery and a photovoltaic panel.
In this embodiment, reference may be made to the above method embodiment for specific implementation steps of a non-contact traveling wave fault location method, which are not described herein again in detail.
The aspects of the present application have been described in detail hereinabove with reference to the accompanying drawings. In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments. Those skilled in the art should also appreciate that the acts and modules referred to in the specification are not necessarily required in the present application. In addition, it can be understood that the steps in the method of the embodiment of the present application may be sequentially adjusted, combined, and deleted according to actual needs, and the modules in the device of the embodiment of the present application may be combined, divided, and deleted according to actual needs.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the applications disclosed herein may be implemented as electronic hardware, computer software, or combinations of both.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Having described embodiments of the present application, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
1. A non-contact traveling wave fault location method is characterized by comprising the following steps:
receiving a space magnetic field signal of the power transmission line through a magnetic field sensor;
comparing the space magnetic field signal with a first magnetic field signal, wherein the first magnetic field signal is a preset threshold range when the power transmission line normally operates;
determining whether to trigger the recording of the fault traveling wave according to the comparison result of the space magnetic field signal and the first magnetic field signal;
if the fault traveling wave recording is triggered, recording a first trigger time, a second trigger time, a third trigger time and a fourth trigger time according to the fault traveling wave recording result;
and calculating a fault distance according to the first trigger time, the second trigger time, the third trigger time and the fourth trigger time, wherein the fault distance is the distance from a fault point of the power transmission line to a monitoring point.
2. A non-contact traveling wave fault location method according to claim 1,
the magnetic field sensor includes: a shield, a coil, and a magnetic core;
the coil is tightly wound on the surface of the magnetic core;
the appearance of magnetic core is the cylinder, the preparation material of magnetic core includes: soft magnetic ferrite, amorphous alloy or silicon steel sheet;
the shielding case is used for preventing the magnetic field inductor from being interfered by external environment;
the sum of the wire diameter lengths of the coils is less than the core length;
the number of turns of the coil is less than 5000 turns.
3. A non-contact traveling wave fault location method according to claim 1,
the spatial magnetic field signal comprises: traveling wave current, magnetic induction and induced electromotive force;
the traveling wave current generates a magnetic field ring around the transmission line, and the magnetic field ring is perpendicular to the propagation direction of the traveling wave current;
the magnetic induction intensity is the magnetic flux density of the magnetic field ring;
the induced electromotive force is generated by the magnetic field sensor inducing the magnetic field loop.
4. The non-contact traveling wave fault location method according to claim 3, wherein if the spatial magnetic field signal is the magnetic induction intensity, the receiving the spatial magnetic field signal of the power transmission line by the magnetic field sensor includes:
obtaining the magnetic induction intensity according to the traveling wave current and the induction distance, wherein the mathematical expression of the magnetic induction intensity is a formula A):
A):
wherein B is the magnetic induction, mu0And the induction distance is the distance from any point in the magnetic field sensor to the power transmission line.
5. The method according to claim 3, wherein if the spatial magnetic field signal is the induced electromotive force, the receiving the spatial magnetic field signal of the power transmission line by the magnetic field sensor comprises:
calculating the induced electromotive force according to the magnetic induction intensity and the traveling wave current, wherein the mathematical expression of the induced electromotive force is a formula B):
B)：
wherein E is the induced electromotive force, n is the number of turns of the magnetic field sensor coil, E is a rate of change in magnetic flux, μ0For vacuum permeability,. pi.is the circumferential ratio,. is(t) is a function of the time variation of the traveling wave current in the induction period, t is induction time, l is the induction distance, l is1And l2The distances between the near edge and the far edge of the magnetic field sensor and the power transmission line are respectively.
6. A non-contact traveling wave fault location method according to any one of claims 1-5,
the comparison result of the spatial magnetic field signal and the first magnetic field signal comprises:
the comparison result of the traveling wave current, the comparison result of the magnetic induction intensity or the comparison result of the induced electromotive force;
the determining whether to trigger the recording of the fault traveling wave according to the comparison result of the space magnetic field signal and the first magnetic field signal includes:
and if the space magnetic field signal is not within the range of the set threshold value of the first magnetic field signal, a fault traveling wave signal exists in the power transmission line, and the fault traveling wave is triggered to be recorded.
7. A non-contact traveling wave fault location method according to claim 1,
the monitoring points comprise: a first monitoring point and a second monitoring point;
the recording of the first trigger time, the second trigger time, the third trigger time and the fourth trigger time according to the recording result of the fault traveling wave comprises:
determining the waveform characteristics of the fault traveling wave signal, wherein the waveform characteristics are that the time difference from the trough to the peak and from the peak to the trough is minimum and the amplitude is maximum;
extracting a waveform having the waveform feature;
according to the extraction result, the waveform with the waveform characteristics recorded for the first time by the first monitoring point is a first waveform, the first waveform corresponds to a fault traveling wave signal and reaches the first monitoring point for the first time from the fault point, and the time corresponding to the peak value of the first waveform is recorded as the first trigger time;
according to the extraction result, the waveform with the waveform characteristics recorded for the first time by the second monitoring point is a second waveform, the second waveform corresponds to the fault traveling wave signal and reaches the second monitoring point for the first time from the fault point, and the time corresponding to the peak value of the second waveform is recorded as the second trigger time;
according to the extraction result, the waveform with the waveform characteristics recorded by the first monitoring point for the second time is a third waveform, the fault traveling wave signal corresponding to the third waveform starts from the first monitoring point and reaches the first monitoring point for the second time after being reflected by the first substation, and the moment corresponding to the peak value of the third waveform is recorded as the third trigger moment;
according to the extraction result, the waveform with the waveform characteristics recorded by the second monitoring point for the second time is a fourth waveform, the fault traveling wave signal corresponding to the fourth waveform starts from the second monitoring point and reaches the second monitoring point for the second time after being reflected by a second transformer substation, and the moment corresponding to the peak value of the fourth waveform is recorded as the fourth trigger moment;
the first transformer substation and the second transformer substation are power systems at two ends of the power transmission line and are used for transmitting fault traveling wave signals.
8. The non-contact traveling wave fault location method of claim 7, comprising:
calculating the transmission speed of the fault traveling wave signal according to the first triggering time, the third triggering time and the distance from the first monitoring point to the first substation, wherein the mathematical expression of the transmission speed of the fault traveling wave signal is a formula C):
C)：
v is the transmission speed of the fault traveling wave signal, L1 is the distance from the first monitoring point to the first substation, t1 is the first trigger time, and t3 is the third trigger time.
9. The method according to claim 1, wherein the calculating a fault distance according to the first trigger time, the second trigger time, the third trigger time, and the fourth trigger time comprises:
the fault distance is calculated by the formula D),
the mathematical expression of the fault distance is formula D):
D)：
wherein x1 is the distance from the fault point to the first monitoring point, x2 is the distance from the fault point to the second monitoring point, v is the transmission speed of the fault traveling wave signal, t1 is the first triggering time, t2 is the second triggering time, t3 is the third triggering time, t4 is the fourth triggering time, and L is the distance from the first monitoring point to the second monitoring point;
and feeding back the calculation result of the fault distance and executing an alarm process.
10. A non-contact traveling wave fault location device, comprising:
the magnetic field sensor is used for receiving a space magnetic field signal of the power transmission line;
the monitoring and wave recording device is used for monitoring and recording the waveform of the fault traveling wave signal and recording the first trigger time, the second trigger time, the third trigger time and the fourth trigger time;
the distance measurement analysis device is used for calculating the fault distance;
the information feedback device is used for feeding back the calculation result of the fault distance and executing an alarm process;
and the power supply device supplies power in the form of a storage battery and a photovoltaic panel.
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