Power cable fault in-trench positioning system and method based on UWB distance measurement and sound

Abstract

The invention discloses a power cable fault in-trench positioning system based on UWB distance measurement and sound. The system comprises a pulse generator, a reference measurement station and a mobile measurement station. The pulse generator periodically applies pulse signals to the power cable to excite a fault point of the power cable to emit sound signals; the reference measurement station obtains a first UWB signal and a first sound signal with a timestamp, sends the first UWB signal and the first sound signal to the mobile measurement station, and receives a second UWB signal sent by the mobile measurement station; and the mobile measurement station establishes communication with the reference measurement station after being movably installed and fixed each time, obtains a second UWB signal generated each time and a second sound signal stamped with a timestamp, and determines the final position of the fault point in combination with the first UWB signal sent by the reference measurement station each time and the first sound signal stamped with the timestamp. By implementing the method, the defects existing in positioning the fault point of the power cable by an existing acoustic-magnetic synchronization method can be overcome, so that the fault point of the power cable can be quickly and accurately positioned.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a system and method for locating a power cable fault in a trench based on UWB ranging and sound. Background Art

[0002] Power cables are an important part of the power system and an important guarantee for the development of the modern national economy and people's lives. Especially in urban areas with high population density, the scale of power cable laying is getting larger and larger as the power system expands with the urbanization process. In order to save the limited land area in the city and beautify the environment, most power cables are buried underground or in cable trenches, which has become the main way of cable laying. With the extension of the service life, power cable failures are inevitable. Although regular power cable safety inspection and troubleshooting can effectively reduce the probability of cable failure, if the fault point of the power cable cannot be located in time when the fault occurs, it will cause great inconvenience and economic losses to the surrounding factories and residents. Therefore, it is necessary for power cable managers to quickly and accurately find the fault point of the faulty cable, thereby improving the reliability of power cable power supply and reducing losses and maintenance costs. Therefore, fast and accurate power cable fault location not only has social and practical significance, but also has engineering practical value.

[0003] The environment in which buried power cables are located is relatively complex, which makes it relatively difficult to detect and locate power cable faults. The power cable fault detection operation steps can be divided into determining the nature of the power cable fault, roughly measuring the fault distance, finding the path of the faulty power cable, and accurately determining the location. The so-called accurate location is to limit the location of the fault point to a very small range, thereby avoiding the impact of large-scale excavation on the surrounding and other pipelines, and at the same time improving the efficiency of troubleshooting.

[0004] At present, the current power cable fault troubleshooting method mainly uses the acoustic-magnetic synchronization method to determine the exact location of the power cable fault point. Specifically, a pulse generator is used to apply a high-voltage DC pulse signal to the faulty power cable. Under the action of the DC pulse signal, the fault point produces a discharge phenomenon and releases sound signals and magnetic field signals to the surrounding environment. These two signals are collected and analyzed respectively, and then the fault point is accurately located.

[0005] However, the above-mentioned method of using the acoustic-magnetic synchronization method to determine the fault point of the power cable has the following defects, which are: (1) The sound signal will propagate along the power cable. Due to its fast propagation speed and slow attenuation, the overall accuracy of using the signal to locate the fault point is low; (2) When the sound signal propagates in the groove, there will be extremely serious multipath propagation phenomenon. Under the superposition of multipath effects, the sound signal will be strengthened in the groove and propagate farther, which introduces a large error in distance judgment and reduces the accuracy of fault point positioning; (3) Near the fault point, the true path of the fault sound signal is submerged in the superposition of the power cable propagation path and the groove multipath, making it impossible to accurately determine the true position of the fault point.

[0006] Therefore, there is an urgent need for a new power cable fault location method that can solve the defects of the existing acoustic-magnetic synchronous method for locating power cable fault points, thereby achieving rapid and accurate positioning of power cable fault points. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a system and method for locating power cable faults in a trench based on UWB ranging and sound, which can solve the defects of the existing acoustic and magnetic synchronization method for locating power cable fault points, thereby realizing rapid and accurate positioning of power cable fault points.

[0008] In order to solve the above technical problems, the embodiment of the present invention provides a system for implementing a power cable fault trench positioning system based on UWB ranging and sound, including a pulse generator, a reference measurement station and a mobile measurement station; wherein,

[0009] The pulse generator is loaded on the power cable in the cable trench;

[0010] The reference measurement station is fixedly installed in the cable trench; the reference measurement station is provided with a first UWB data transmission module and a first microphone connected to the power cable;

[0011] The mobile measuring station is movably installed in the cable trench, and after each movably installed, it maintains a certain distance from the reference measuring station and establishes communication with the reference measuring station; the mobile measuring station is provided with a second UWB data transmission module, a data calculation module and a second microphone connected to the power cable; the second UWB data transmission module of the mobile measuring station and the first UWB data transmission module of the reference measuring station realize communication interconnection and establishment;

[0012] The pulse generator is used to periodically apply a high-voltage DC pulse signal to the power cable, so that when a fault point exists in the power cable, the fault point can be stimulated to emit a sound signal;

[0013] The reference measurement station is used to timestamp the first sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator based on the first microphone collected in real time, and generate a first UWB signal using the first UWB data transmission module, and send the first sound signal with the timestamp together with the first UWB signal to the mobile measurement station; and use the first UWB data transmission module to receive the second UWB signal sent by the mobile measurement station; wherein the first UWB signal carries the ID number of the reference measurement station and the timestamp and synchronous positioning information generated by it; and the second UWB signal carries the ID number of the mobile measurement station and the timestamp and synchronous positioning information generated by it;

[0014] The mobile measuring station is used to generate a second UWB signal using the second UWB data transmission module and send it to the reference measuring station each time the mobile measuring station establishes communication with the reference measuring station after being installed and fixed, and to receive the first UWB signal and the first sound signal with a timestamp sent by the reference measuring station, and further to timestamp the second sound signal generated when the high-voltage DC pulse signal applied to the power cable by the pulse generator is collected in real time by the second microphone; and

[0015] The final location of the fault point in the power cable is determined using the data calculation module based on the second UWB signal and the second sound signal with a time stamp obtained after each active installation and fixation, and combined with the first UWB signal and the first sound signal with a time stamp sent by the reference measurement station each time.

[0016] Wherein, the data calculation module includes:

[0017] A relative distance measurement submodule, for determining that the total number of times the mobile measurement station establishes communication with the reference measurement station after being installed and fixed is k, and based on the second UWB signal generated by the mobile measurement station after 1 to k times of installation and fixation and its corresponding first UWB signal received from the reference measurement station, and the first UWB signal generated by the reference measurement station 1 to k times and its corresponding second UWB signal received from the mobile measurement station, obtain k relative distances formed between the mobile measurement station and the reference measurement station after 1 to k times of installation and fixation, and further combine the preset coordinate position of the reference measurement station to obtain the coordinate position of the mobile measurement station after 1 to k times of installation and fixation; wherein k is a positive integer greater than 1;

[0018] A sound signal decomposition submodule is used to intercept the second sound signal with a time stamp collected by the mobile measurement station at times 1 to k and the first sound signal with a time stamp collected by the reference measurement station at times 1 to k, so as to obtain the signal segments corresponding to the intercepted signal of the mobile measurement station and the reference measurement station at times 1 to k, and use a preset ensemble empirical mode decomposition (EEMD) algorithm to decompose the intercepted 2k signal segments to obtain the eigenmode function groups corresponding to the mobile measurement station and the reference measurement station at times 1 to k;

[0019] A signal time difference processing submodule, for extracting the cable propagation path signals and atmospheric propagation path signals corresponding to the mobile measurement station and the reference measurement station at times 1 to k based on the eigenmode function groups of the mobile measurement station and the reference measurement station outputted by the sound signal decomposition submodule, so as to further obtain the time delay differences formed by the sound signals propagating in the power cable and the air at times 1 to k for the mobile measurement station and the reference measurement station;

[0020] An air propagation speed acquisition submodule, for calculating k first propagation speeds of the sound signal propagating in the air based on the k relative distances between the mobile measuring station and the reference measuring station after 1 to k times of active installation and fixation outputted by the relative distance measurement submodule, and combining the atmospheric propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station at 1 to k times;

[0021] A cable propagation speed acquisition submodule, for calculating k second propagation speeds of the sound signal when propagating in the power cable based on the k relative distances between the mobile measuring station and the reference measuring station after 1 to k times of active installation and fixation outputted by the relative distance measurement submodule, and combining the cable propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station at 1 to k times;

[0022] The fault point positioning submodule is used to construct an objective function based on the time delay difference formed by the mobile measuring station when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position after being installed and fixed, and the time delay difference formed by the reference measuring station when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position, and combined with the obtained k first propagation speeds of the sound signal when propagating in the air and the k second propagation speeds when propagating in the power cable, and use the particle swarm optimization algorithm and the Levenberg-Marquardt algorithm to find the optimal solution of the objective function, and the obtained optimal solution is output as the final position of the fault point in the power cable.

[0023] Among them, the objective function is in,

[0024] is the estimated position of the fault point in the power cable; p is the quantity to be estimated at the position of the fault point; the superscript j represents the number of measurements, and j=1, 2, ..., k; the subscript i represents the type of measurement site, i=1 represents the reference measurement site, and i=2 represents the mobile measurement site; represents the coordinate position of the i-th type measurement station at the jth time, represents the coordinate position of the reference measuring station at the jth time and they are defined as represents the coordinate position of the mobile measuring station at the jth time and they are defined as represents the relative distance between the mobile measuring station and the reference measuring station after the mobile measuring station is installed and fixed for the jth time; is the first propagation speed of the sound signal when it propagates in the air for the jth time; is the second propagation speed of the sound signal when it propagates in the jth power cable; represents the time delay difference caused by the sound signal propagating in the power cable and the air at the i-th measurement site for the jth time, represents the time delay difference formed by the reference measurement station when the sound signal propagates in the power cable and the air for the jth time, It represents the time delay difference formed by the mobile measuring station when the sound signal propagates in the power cable and the air for the jth time.

[0025] Among them, through the formula Obtain the k-th corresponding eigenmode function group of the reference measurement station; and, by formula Get the k-th corresponding eigenmode function group of the mobile measuring station; where,

[0026] From imf1 1,k , extracting the cable propagation path signal corresponding to the kth time at the reference measurement station; and from imf3 1,k ~imf5 1,k , extracting the atmospheric propagation path signal corresponding to the kth time at the reference measurement station;

[0027] From imf1 2,k , extracting the cable propagation path signal corresponding to the kth time at the mobile measuring station; and from imf3 2,k ~imf5 2,k , extracting the atmospheric propagation path signal corresponding to the kth time at the mobile measurement station;

[0028] m represents the maximum number of eigenmode function groups.

[0029] Among them, through the formula The time delay difference formed by the reference measuring station when the sound signal propagates in the power cable and the air for the kth time is calculated. and the time delay difference formed by the mobile measuring station when the sound signal propagates in the power cable and the air for the kth time in,

[0030] Through the threshold method, we get represents the k-th time delay of the i-th type measurement station on the power cable propagation path, represents the k-th time delay of the reference measurement station on the power cable propagation path, represents the k-th time delay of the mobile measuring station on the power cable propagation path; represents the k-th time delay of the i-th type measurement station on the air propagation path, represents the k-th time delay of the reference measurement station on the air propagation path, represents the k-th time delay of the mobile measuring station on the air propagation path; f s is a fixed threshold parameter.

[0031] Among them, through the formula Calculate the first propagation speed of the sound signal when it propagates in the air for the kth time; and, through the formula The second propagation velocity of the sound signal when it propagates in the power cable for the kth time is calculated.

[0032] Among them, the k-th time delay of the reference measurement station on the air propagation path is and the kth time delay of the mobile measuring station on the air propagation path They are all predicted by the Bayesian filtering method based on the previous k-1 time delays on the air propagation path.

[0033] The embodiment of the present invention further provides a method for locating a power cable fault in a trench based on UWB ranging and sound, which is implemented on the aforementioned power cable fault locating system based on UWB ranging and sound, and the method comprises the following steps:

[0034] The pulse generator periodically applies a high-voltage DC pulse signal to the power cable, so that when there is a fault point in the power cable, the fault point can be stimulated to emit a sound signal;

[0035] The reference measurement station generates a first UWB signal, receives a second UWB signal sent by the mobile measurement station, and timestamps a first sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator based on real-time acquisition, and further sends the timestamped first sound signal together with the first UWB signal to the mobile measurement station; wherein the first UWB signal carries the ID number of the reference measurement station and the timestamp and synchronous positioning information generated by it; and the second UWB signal carries the ID number of the mobile measurement station and the timestamp and synchronous positioning information generated by it;

[0036] When the mobile measuring station establishes communication with the reference measuring station after each active installation and fixation, it generates a second UWB signal and sends it to the reference measuring station, and timestamps the second sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator in real time, and further determines the final location of the fault point in the power cable by combining the first UWB signal sent by the reference measuring station and the first sound signal with the timestamp.

[0037] The mobile measuring station generates a second UWB signal and sends it to the reference measuring station each time it establishes communication with the reference measuring station after each active installation and fixation, and timestamps the second sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator in real time, and further combines the first UWB signal sent by the reference measuring station and the first sound signal with the timestamp to determine the final position of the fault point in the power cable. The specific steps include:

[0038] Determine that the total number of times the mobile measurement station establishes communication with the reference measurement station after being installed and fixed is k, and based on the second UWB signal generated by the mobile measurement station after 1 to k times of installation and fixation and its corresponding first UWB signal received from the reference measurement station, as well as the first UWB signal generated by the reference measurement station 1 to k times and its corresponding second UWB signal received from the mobile measurement station, obtain k relative distances formed between the mobile measurement station and the reference measurement station after 1 to k times of installation and fixation, and further combine the preset coordinate position of the reference measurement station to obtain the coordinate position of the mobile measurement station after 1 to k times of installation and fixation; wherein k is a positive integer greater than 1;

[0039] The second sound signal with a time stamp collected by the mobile measuring station at times 1 to k and the first sound signal with a time stamp collected by the reference measuring station at times 1 to k are intercepted to obtain the signal segments corresponding to the mobile measuring station and the reference measuring station at times 1 to k, and the 2k intercepted signal segments are decomposed using a preset ensemble empirical mode decomposition (EEMD) algorithm to obtain the eigenmode function groups corresponding to the mobile measuring station and the reference measuring station at times 1 to k;

[0040] Based on the eigenmode function groups of the mobile measuring station and the reference measuring station at 1 to k times, the cable propagation path signals and the atmospheric propagation path signals corresponding to the mobile measuring station and the reference measuring station at 1 to k times are extracted to further obtain the time delay difference formed by the sound signal propagating in the power cable and the air at 1 to k times of the mobile measuring station and the reference measuring station;

[0041] Based on the k relative distances between the mobile measuring station and the reference measuring station after being installed and fixed for 1 to k times, and in combination with the atmospheric propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station for 1 to k times, k first propagation velocities of the sound signal propagating in the air are calculated;

[0042] Based on k relative distances between the mobile measuring station and the reference measuring station after being installed and fixed for 1 to k times, and in combination with the cable propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station for 1 to k times, k second propagation velocities of the sound signal when propagating in the power cable are calculated;

[0043] According to the time delay difference formed by the mobile measuring station 1 to k times when the sound signal propagates in the power cable and the air and its coordinate position after being installed and fixed, and the time delay difference formed by the reference measuring station 1 to k times when the sound signal propagates in the power cable and the air and its coordinate position, and combined with the obtained k first propagation speeds of the sound signal when propagating in the air and the k second propagation speeds when propagating in the power cable, an objective function is constructed, and the particle swarm optimization algorithm and the Levenberg-Marquardt algorithm are used to find the optimal solution of the objective function, and the obtained optimal solution is output as the final position of the fault point in the power cable.

[0044] Implementing the embodiments of the present invention has the following beneficial effects:

[0045] 1. The present invention realizes the rapid location of cable fault points based on UWB system and sound technology, integrates the reference measurement station and the mobile measurement station for synchronous data transmission, greatly reduces the system complexity and system power consumption, and thus solves the defects of the existing acoustic and magnetic synchronization method for locating power cable fault points;

[0046] 2. The present invention uses a reference measuring station and a mobile measuring station to form a relative coordinate system, thereby obtaining high-precision position information in the local coordinate system, and then based on the relative distance between the reference measuring station and the mobile measuring station, calibrates the propagation speed of the sound signal in the power cable and the air in real time, thereby improving the fault location accuracy;

[0047] 3. The present invention converts the fault point location estimation problem in the objective function into a nonlinear weighted least squares problem, and then uses a heuristic algorithm to solve it to gradually improve the fault point location accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0049] Figure 1 A schematic diagram of the structure of a power cable fault trench positioning system based on UWB ranging and sound provided in an embodiment of the present invention;

[0050] Figure 2 A functional structure diagram of a reference measuring station and a mobile measuring station in a power cable fault trench positioning system based on UWB ranging and sound provided by an embodiment of the present invention;

[0051] Figure 3 A functional structure diagram of a data calculation module included in a mobile measurement station in a power cable fault trench positioning system based on UWB ranging and sound provided by an embodiment of the present invention;

[0052] Figure 4 A schematic diagram of the propagation of sound signals in a power cable trench in a power cable fault trench positioning system based on UWB ranging and sound provided by an embodiment of the present invention;

[0053] Figure 5 A schematic diagram of multipath component analysis of sound signals in a power cable fault trench positioning system based on UWB ranging and sound provided by an embodiment of the present invention;

[0054] Figure 6A schematic diagram of an application scenario of a power cable fault trench positioning system based on UWB ranging and sound provided in an embodiment of the present invention;

[0055] Figure 7 A flow chart of a method for locating a power cable fault in a trench based on UWB ranging and sound is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0057] like Figure 1 and Figure 2 As shown, in an embodiment of the present invention, a power cable fault trench positioning system based on UWB ranging and sound is proposed, including a pulse generator 1, a reference measurement station 2 and a mobile measurement station 3; wherein,

[0058] The pulse generator 1 is loaded on the power cable L in the cable trench;

[0059] The reference measuring station 2 is fixedly installed in the cable trench; the reference measuring station 2 is provided with a first UWB data transmission module 21 and a first microphone 22 connected to the power cable L;

[0060] The mobile measuring station 3 is installed in the cable trench, and after each installation, it maintains a certain distance from the reference measuring station 2 and establishes communication with the reference measuring station 2; the mobile measuring station 3 is provided with a second UWB data transmission module 31, a data calculation module 33 and a second microphone 32 connected to the power cable L; the second UWB data transmission module 31 of the mobile measuring station 3 and the first UWB data transmission module 21 of the reference measuring station 2 are interconnected and established for communication, and can realize functions such as positioning, ranging and time synchronization;

[0061] The pulse generator 1 is used to periodically (once every 30 seconds) apply a high-voltage DC pulse signal to the power cable L, so that when there is a fault point in the power cable L, the fault point can be stimulated to emit a sound signal;

[0062] The reference measuring station 2 is used to timestamp the first sound signal generated when the power cable L is applied with a high-voltage DC pulse signal by the pulse generator 1 based on the real-time acquisition of the first microphone 22, and generate a first UWB signal using the first UWB data transmission module 21, and send the first sound signal with the timestamp together with the first UWB signal to the mobile measuring station 3; and receive the second UWB signal sent by the mobile measuring station 3 using the first UWB data transmission module 21; wherein the first UWB signal carries the ID number of the reference measuring station and the timestamp and synchronous positioning information generated by it; and the second UWB signal carries the ID number of the mobile measuring station and the timestamp and synchronous positioning information generated by it;

[0063] The mobile measuring station 3 is used to generate a second UWB signal using the second UWB data transmission module 31 and send it to the reference measuring station 2 each time the mobile measuring station 3 establishes communication with the reference measuring station 2 after being installed and fixed, and receive the first UWB signal and the first sound signal with a timestamp sent by the reference measuring station 2, and further timestamp the second sound signal generated when the high-voltage DC pulse signal applied to the power cable L by the pulse generator 1 is collected in real time by the second microphone 32; and,

[0064] The final position of the fault point in the power cable L is determined using the data calculation module 33 based on the second UWB signal and the second sound signal with a time stamp obtained after each active installation and fixation, and combined with the first UWB signal and the first sound signal with a time stamp sent by the reference measurement station 2 each time.

[0065] It can be understood that first, a reference site is randomly selected (as far away from the fault point as possible), and then the reference measurement station 2 is placed on the reference site; secondly, the position of the mobile measurement station 3 can be changed multiple times. Each time the position is changed, the mobile measurement station 3 will form a relative coordinate system with the reference measurement station 2 through the UWB communication protocol, and then obtain high-precision position information in the local coordinate system, and then synchronously measure the sound signal. After that, the mobile measurement station 3 counts the results of each measurement to estimate the final position of the fault point in the power cable. At this time, the number of times the mobile measurement station 3 establishes communication and performs measurements with the reference measurement station 2 can be changed once to measure multiple times at the position or only once, which is specifically set according to the actual situation.

[0066] It should be noted that the structures of the microphones used in the reference measurement station 2 and the mobile measurement station 3 are the same, and the sampling frequency of the sound signal is 48 kHz.

[0067] In the embodiment of the present invention, after each communication measurement is completed, the data collected by the reference measurement station 2 is sent to the mobile measurement station 3 , and a fast position estimation of the fault point is performed in the data calculation module 33 of the mobile measurement station 3 .

[0068] like Figure 3 As shown, the data calculation module 33 includes a relative distance measurement submodule 331, a sound signal decomposition submodule 332, a signal time difference processing submodule 333, an air propagation speed acquisition submodule 334, a cable propagation speed acquisition submodule 335 and a fault point location submodule 336.

[0069] At this time, the relative distance measurement submodule 331 is used to determine that the total number of times the mobile measurement station 3 establishes communication with the reference measurement station 2 after being installed and fixed flexibly (i.e., the total number of measurements) is k, and based on the second UWB signal generated by the mobile measurement station 3 after 1 to k times of active installation and fixation and its corresponding first UWB signal received from the reference measurement station 2, as well as the first UWB signal generated by the reference measurement station 2 1 to k times and its corresponding second UWB signal received from the mobile measurement station 3, k relative distances formed between the mobile measurement station 3 and the reference measurement station 2 after 1 to k times of active installation and fixation are obtained, and further combined with the preset coordinate position of the reference measurement station 2, the coordinate position of the mobile measurement station 3 after 1 to k times of active installation and fixation is obtained; wherein k is a positive integer greater than 1.

[0070] It should be noted that the relative distance measurement submodule 331 obtains k relative distances between the mobile measurement station 3 and the reference measurement station 2 after 1 to k active installations based on the UWB ranging principle. At this time, the UWB ranging principle is implemented based on the two-way time of flight method (TW-TOF), that is, each UWB data transmission module will generate an independent timestamp from the start. For example, the first UWB data transmission module 21 of the reference measurement station 2 transmits a first UWB signal of a request nature at Ta1 on its timestamp, so that the second UWB data transmission module 22 of the mobile measurement station 2 can receive the first UWB signal at Tb1 on its timestamp, and after a certain processing means is applied to the first UWB signal, the second UWB data transmission module 22 of the mobile measurement station 2 transmits a second UWB signal of a response nature at time Tb2, which is received by the first UWB data transmission module 21 of the reference measurement station 2 at its own timestamp time Ta. Thus, the flight time of the pulse signal between the two UWB data transmission modules can be calculated, so as to determine the relative distance of the flight as S=speed of light C×[(Ta2-Ta1)-(Tb2-Tb1)].

[0071] For example, for the kth measurement, the mobile measurement station 3 and the reference measurement station 2 perform positioning, time synchronization and ranging through the UWB communication protocol. The coordinate position of the reference measurement station 2 at the kth time is recorded as The coordinate position of the mobile measuring station 3 at the kth time is in, is the relative distance between the mobile measuring station 3 and the reference measuring station 2 at the kth measurement, which is obtained by the UWB ranging principle.

[0072] At this time, the sound signal decomposition submodule 332 is used to intercept the second sound signal with a time stamp collected by the mobile measurement station 3 at times 1 to k and the first sound signal with a time stamp collected by the reference measurement station 2 at times 1 to k, so as to obtain the signal segments corresponding to the mobile measurement station 3 and the reference measurement station 2 respectively intercepted at times 1 to k, and use the preset ensemble empirical mode decomposition EEMD algorithm to decompose the intercepted 2k signal segments to obtain the eigenmode function groups corresponding to the mobile measurement station 3 and the reference measurement station 2 respectively at times 1 to k.

[0073] For example, first, for the kth measurement, the first sound signal with a time stamp collected by the reference measurement station 2 is recorded as And the second sound signal with a time stamp collected by the mobile measuring station 3 is recorded as

[0074] Then, if Figure 4 and Figure 5 As shown in Figure 1, the propagation paths of sound signals are mainly divided into power cable propagation path, atmospheric line-of-sight propagation path and atmospheric multipath propagation path. Since the propagation speed of sound signals in power cables is greater than 5000m / s, and the propagation speed in air is about 340m / s, both reference measurement station 2 and mobile measurement station 3 will first receive the signal on the power cable propagation path, and then the signal on the atmospheric line-of-sight propagation path. There is a certain time delay difference between the two (such as Figure 5 As shown in FIG. 1 ), when the mobile measuring station 3 gradually approaches the fault point, the time delay difference gradually decreases and becomes difficult to separate, which is also the biggest difficulty and challenge currently faced by the acoustic-magnetic synchronization method.

[0075] Since the sound signal excited by the fault point is a typical pulse signal with broadband characteristics, the attenuation degree of the high-frequency component of the broadband signal in the atmosphere is much greater than that of the metal medium. Therefore, the signal on the power cable propagation path and the signal on the atmospheric propagation path can be separated by performing empirical mode decomposition (EMD) on it. In order to further improve the decomposition accuracy and avoid aliasing, the integrated empirical mode decomposition (EEMD) method can be used to achieve this. Therefore, for the kth measurement, the first sound signal and second sound signal Perform EEMD decomposition respectively, and obtain the intrinsic mode function (IMF, Intrinsic Mode Function) group, denoted as That is, the eigenmode function group corresponding to the reference measurement station 2 at the kth time; and, denoted as That is, the eigenmode function group corresponding to the kth time of mobile measuring station 3 Where m is the maximum number of eigenmode function groups.

[0076] It should be noted that the maximum number of iterations of the EEMD is predefined to be 100, the added noise signal-to-noise ratio is 20 dB, and the maximum number of decomposition layers of the eigenmode function group is 10 layers.

[0077] At this time, the signal time difference processing submodule 333 is used to extract the cable propagation path signals and atmospheric propagation path signals corresponding to the mobile measurement station 3 and the reference measurement station 2 at times 1 to k based on the eigenmode function groups output by the sound signal decomposition submodule 332, so as to further obtain the time delay difference formed by the mobile measurement station 3 and the reference measurement station 2 at times 1 to k when the sound signal propagates in the power cable and the air.

[0078] For example, first, for the kth measurement, imf1 i,k Usually, it contains high-frequency components in the signal, but in signal denoising applications, it is considered to carry a large amount of high-frequency noise sound signals. In the present invention, since the pulse signal is a broadband signal, the sound signal propagated along the power cable path will be in the imf1 i,k Therefore, from imf1 1,k Extract the cable propagation path signal corresponding to the kth time of reference measurement station 2, and extract the signal from imf1 2,k The cable propagation path signal corresponding to the mobile measuring station 3 at the kth time is extracted.

[0079] Since atmospheric propagation attenuates the high-frequency components of sound signals quickly, The strong energy atmospheric propagation path signal is observed in the imf3, thus realizing the separation of the power cable propagation path and the atmospheric propagation path signal. 1,k ~imf5 1,k Extract the atmospheric propagation path signal corresponding to the kth time of the reference measurement station 2 from imf3 2,k ~imf5 2,k The atmospheric propagation path signal corresponding to the kth time of the mobile measuring station 3 is extracted.

[0080] Secondly, the threshold method formula (1) is used to obtain the k-th time delay of the i-th type measurement station on the power cable propagation path: and the kth time delay of the i-th measurement station on the air propagation path

[0081]

[0082] in, represents the k-th time delay of reference measurement station 2 on the power cable propagation path, represents the k-th time delay of mobile measuring station 3 on the power cable propagation path; represents the k-th time delay of reference measurement station 2 on the air propagation path, represents the kth time delay of mobile measuring station 3 on the air propagation path; f s is a fixed threshold parameter.

[0083] Furthermore, by using formula (2), we can get the time delay difference when the sound signal propagates in the power cable and the atmosphere:

[0084]

[0085] in, represents the time delay difference formed by the reference measuring station 2 when the sound signal propagates in the power cable and the air for the kth time; It represents the time delay difference formed by the mobile measuring station 3 at the kth time when the sound signal propagates in the power cable and the air.

[0086] It should be noted that the k-th time delay of reference measurement station 2 on the air propagation path is and the kth time delay of mobile measuring station 3 on the air propagation path They can all be predicted based on the previous k-1 time delays on the air propagation path using the Bayesian filtering method.

[0087] For example, in order to improve the estimation accuracy of the time delay of the sound signal on the air propagation path, the k-th time delay of the reference measurement station 2 and the mobile measurement station 3 on the air propagation path can be calculated based on the measurement data of the previous k-1 moments and the following formula (3): and Make predictions.

[0088]

[0089] Then, from the Moment and Cut off at each moment and signal and fill it with zeros at the end to make it the same length, denoted as and

[0090] Then, the collected acoustic signals are analyzed based on the EEMD algorithm. and Decompose, and the obtained eigenmode function groups are denoted as and

[0091] Furthermore, based on equation (1), the time delays of the reference measurement station 2 and the mobile measurement station 3 on the kth air propagation path are obtained: and Then update the posterior probability according to formula (4).

[0092]

[0093] in, is a normalization constant to ensure It is worth noting that when i=1, it is the reference measurement station 2. Since the reference measurement station 2 is stationary, the Bayesian filter can be equivalent to the mean filter.

[0094] At this time, the air propagation speed acquisition submodule 334 is used to calculate the k relative distances between the mobile measurement station 3 and the reference measurement station 2 after 1 to k times of active installation and fixation based on the corresponding output of the relative distance measurement submodule 331, and combined with the atmospheric propagation path signals correspondingly extracted by the mobile measurement station 3 and the reference measurement station 2 at 1 to k times, to obtain the k first propagation speeds of the sound signal when propagating in the air.

[0095] For example, for the kth measurement, based on formula (1), and through formula (5), the first propagation velocity of the sound signal when it propagates in the air for the kth time is calculated:

[0096]

[0097] At this time, the cable propagation speed acquisition submodule 335 is used to calculate the k relative distances between the mobile measuring station 3 and the reference measuring station 2 after 1 to k times of active installation and fixation based on the corresponding output of the relative distance measurement submodule 331, and combined with the cable propagation path signals extracted from the mobile measuring station 3 and the reference measuring station 2 respectively at 1 to k times, to obtain the k second propagation speeds of the sound signal when propagating in the power cable.

[0098] For example, for the kth measurement, based on formula (1), and through formula (6), the second propagation velocity of the sound signal when it propagates in the power cable for the kth time is calculated as:

[0099]

[0100] At this time, the fault point positioning submodule 336 is used to construct an objective function based on the time delay difference formed by the mobile measuring station 3 when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position after active installation and fixation, and the time delay difference formed by the reference measuring station 2 when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position, and combined with the obtained k first propagation speeds of the sound signal when propagating in the air and the k second propagation speeds when propagating in the power cable, and use the particle swarm optimization algorithm and the Levenberg-Marquardt algorithm to find the optimal solution of the objective function, and the obtained optimal solution is output as the final position of the fault point in the power cable.

[0101] The objective function is expressed as follows:

[0102]

[0103] in, is the estimated position of the fault point in the power cable L; p is the quantity to be estimated at the fault point; the superscript j represents the number of measurements, and j = 1, 2, ..., k; the subscript i represents the type of measurement site, i = 1 represents the reference measurement site 2, and i = 2 represents the mobile measurement site 3; represents the coordinate position of the i-th type measurement station at the jth time, represents the coordinate position of the reference measuring station 2 at the jth time and both are represents the coordinate position of mobile measuring station 3 at the jth time and are represents the relative distance between the mobile measuring station 3 and the reference measuring station 2 after the jth active installation and fixation; is the first propagation speed of the sound signal when it propagates in the air for the jth time; is the second propagation speed of the sound signal when it propagates in the jth power cable; represents the time delay difference caused by the sound signal propagating in the power cable and the air at the i-th measurement site for the jth time, represents the time delay difference formed by the reference measurement station 2 when the sound signal propagates in the power cable and the air for the jth time, It represents the time delay difference formed by the mobile measuring station 3 when the sound signal propagates in the power cable and the air for the jth time.

[0104] At this time, the inventor found that the method of estimating the position through the objective function can be converted into a nonlinear least squares problem. Since the measurement information will increase with the increase of the number of measurements, it is necessary to use an intelligent search algorithm, Newton descent method or Levenberg-Marquardt algorithm to solve it. Therefore, the particle swarm optimization algorithm and the Levenberg-Marquardt algorithm are used to find the optimal solution to the objective function, and the optimal solution output is the final position of the fault point in the power cable.

[0105] It should be noted that using intelligent search algorithms, Newton descent methods or Levenberg-Marquardt algorithms to solve nonlinear least square problems is a common technical means in this field and will not be described in detail here.

[0106] like Figure 6 As shown, an application scenario of a power cable fault trench positioning system based on UWB ranging and sound in an embodiment of the present invention is further described as follows:

[0107] exist Figure 6 In the process of locating the cable fault point in the urban cable trench, a reference measuring station, a mobile measuring station and a pulse generator are used. At this time, the pulse generator is used to pass a high-voltage pulse electrical signal to the faulty cable at a fixed period to stimulate the fault point to emit a sound signal. The reference measuring station is arranged at a distance away from the fault point, within a range of 20 to 30 meters, and its coordinates do not need to be manually calibrated. The mobile measuring station is carried by the operator. After measuring 3 to 5 times at a single measuring position, it moves a distance towards the fault point. After 2 to 3 transformations, the precise location of the fault point can be obtained.

[0108] First, the reference measurement station and the mobile measurement station are clock synchronized through the UWB communication protocol. In the kth measurement process, the coordinates of the reference measurement station are recorded as The coordinates of the mobile reference station are

[0109]

[0110] The pulse generator generates a high-voltage pulse signal at 30-second intervals, which stimulates the fault point to emit a sound signal, and collects the sound signal through the corresponding microphones set on the reference measurement station and the mobile measurement station. At this time, the sampling frequency of the sound signal is 48kHz.

[0111] The reference measurement station encapsulates the first sound signal with the time stamp and the first UWB signal into a data packet, and sends the data packet to the mobile measurement station via the first UWB data transmission module.

[0112] The mobile measurement station constructs the objective function formula (7) according to the above formulas (1) to (6) based on the second UWB signal and the second sound signal with a time stamp generated by itself and the first UWB signal and the first sound signal with a time stamp generated by the reference measurement station. The particle swarm optimization algorithm (PSO) is further used to estimate the position of the fault point based on formula (7), and then it is used as the initial value to accurately solve the coordinates of the fault point based on the LM algorithm.

[0113] like Figure 7 As shown, a method for locating a power cable fault trench based on UWB ranging and sound is provided in an embodiment of the present invention. The method is implemented on a power cable fault trench locating system based on UWB ranging and sound in an embodiment of the present invention. The method comprises the following steps:

[0114] Step S1, the pulse generator periodically applies a high-voltage DC pulse signal to the power cable, so that when there is a fault point in the power cable, the fault point can be stimulated to emit a sound signal;

[0115] Step S2, the reference measurement station generates a first UWB signal, receives a second UWB signal sent by the mobile measurement station, and adds a timestamp to a first sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator based on real-time acquisition, and further sends the timestamped first sound signal together with the first UWB signal to the mobile measurement station; wherein the first UWB signal carries the ID number of the reference measurement station and the timestamp and synchronous positioning information generated by it; and the second UWB signal carries the ID number of the mobile measurement station and the timestamp and synchronous positioning information generated by it;

[0116] Step S3: When the mobile measuring station establishes communication with the reference measuring station after each active installation and fixation, it generates a second UWB signal and sends it to the reference measuring station, and timestamps the second sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator in real time, and further determines the final location of the fault point in the power cable by combining the first UWB signal received from the reference measuring station and the first sound signal with the timestamp.

[0117] The specific process is as follows: in step S1, the pulse generator periodically (eg, once every 30 seconds) applies a high-voltage DC pulse signal to the power cable, so that when a fault point exists in the power cable, the fault point can be stimulated to emit a sound signal.

[0118] In step S2, the reference measurement station generates a first UWB signal carrying the ID number of the reference measurement station and a timestamp and synchronization positioning information generated by the reference measurement station, and receives a second UWB signal sent by the mobile measurement station carrying the ID number of the mobile measurement station and a timestamp and synchronization positioning information generated by the mobile measurement station, and timestamps the first sound signal generated when a high-voltage DC pulse signal is applied to the power cable by a pulse generator based on real-time collection, and further sends the first sound signal with the timestamp to the mobile measurement station together with the first UWB signal.

[0119] In step S3, first, the total number of times the mobile measurement station establishes communication with the reference measurement station after being installed and fixed is determined to be k, and based on the second UWB signal generated by the mobile measurement station after 1 to k times of installation and fixation and its corresponding first UWB signal received from the reference measurement station, as well as the first UWB signal generated by the reference measurement station 1 to k times and its corresponding second UWB signal received from the mobile measurement station, k relative distances formed between the mobile measurement station and the reference measurement station after 1 to k times of installation and fixation are obtained, and further combined with the preset coordinate position of the reference measurement station, the coordinate position of the mobile measurement station after 1 to k times of installation and fixation is obtained; wherein k is a positive integer greater than 1;

[0120] Next, the second sound signal with a time stamp collected by the mobile measuring station at times 1 to k and the first sound signal with a time stamp collected by the reference measuring station at times 1 to k are intercepted to obtain the signal segments corresponding to the mobile measuring station and the reference measuring station at times 1 to k, and the 2k intercepted signal segments are decomposed using a preset ensemble empirical mode decomposition (EEMD) algorithm to obtain the eigenmode function groups corresponding to the mobile measuring station and the reference measuring station at times 1 to k;

[0121] Next, based on the eigenmode function groups of the mobile measuring station and the reference measuring station at 1 to k times, the cable propagation path signals and the atmospheric propagation path signals corresponding to the mobile measuring station and the reference measuring station at 1 to k times are extracted, so as to further obtain the time delay difference formed by the sound signal propagating in the power cable and the air at 1 to k times of the mobile measuring station and the reference measuring station;

[0122] Next, based on the k relative distances between the mobile measuring station and the reference measuring station after being installed and fixed at the 1st to kth times, and in combination with the atmospheric propagation path signals correspondingly extracted at the mobile measuring station and the reference measuring station at the 1st to kth times, the k first propagation velocities of the sound signal propagating in the air are calculated;

[0123] Next, based on the k relative distances between the mobile measuring station and the reference measuring station after being installed and fixed at the 1st to kth times, and combined with the cable propagation path signals correspondingly extracted at the mobile measuring station and the reference measuring station at the 1st to kth times, the k second propagation velocities of the sound signal when propagating in the power cable are calculated;

[0124] Finally, according to the time delay difference formed by the mobile measuring station when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position after movable installation and fixation, as well as the time delay difference formed by the reference measuring station when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position, and combined with the obtained k first propagation velocities of the sound signal when propagating in the air and the k second propagation velocities when propagating in the power cable, an objective function is constructed, and the particle swarm optimization algorithm and the Levenberg-Marquardt algorithm are used to find the optimal solution of the objective function, and the optimal solution is output as the final position of the fault point in the power cable.

[0125] Implementing the embodiments of the present invention has the following beneficial effects:

[0126] 1. The present invention realizes the rapid location of cable fault points based on UWB system and sound technology, integrates the reference measurement station and the mobile measurement station for synchronous data transmission, greatly reduces the system complexity and system power consumption, and thus solves the defects of the existing acoustic and magnetic synchronization method for locating power cable fault points;

[0127] 2. The present invention uses a reference measuring station and a mobile measuring station to form a relative coordinate system, thereby obtaining high-precision position information in the local coordinate system, and then based on the relative distance between the reference measuring station and the mobile measuring station, calibrates the propagation speed of the sound signal in the power cable and the air in real time, thereby improving the fault location accuracy;

[0128] 3. The present invention converts the fault point location estimation problem in the objective function into a nonlinear weighted least squares problem, and then uses a heuristic algorithm to solve it to gradually improve the fault point location accuracy.

[0129] It is worth noting that in the above system embodiment, the various system modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the various functional modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0130] A person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, CD-ROM, etc.

[0131] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power cable fault trench positioning system based on UWB ranging and sound, characterized in that: It includes a pulse generator, a reference measuring station and a mobile measuring station; wherein, The pulse generator is loaded on the power cable in the cable trench; The reference measurement station is fixedly installed in the cable trench; the reference measurement station is provided with a first UWB data transmission module and a first microphone connected to the power cable; The mobile measuring station is movably installed in the cable trench, and after each movably installed, it maintains a certain distance from the reference measuring station and establishes communication with the reference measuring station; the mobile measuring station is provided with a second UWB data transmission module, a data calculation module and a second microphone connected to the power cable; the second UWB data transmission module of the mobile measuring station and the first UWB data transmission module of the reference measuring station realize communication interconnection and establishment; The pulse generator is used to periodically apply a high-voltage DC pulse signal to the power cable, so that when a fault point exists in the power cable, the fault point can be stimulated to emit a sound signal; The reference measurement station is used to timestamp the first sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator based on the first microphone collected in real time, and generate a first UWB signal using the first UWB data transmission module, and send the first sound signal with the timestamp together with the first UWB signal to the mobile measurement station; and use the first UWB data transmission module to receive the second UWB signal sent by the mobile measurement station; wherein the first UWB signal carries the ID number of the reference measurement station and the timestamp and synchronous positioning information generated by it; and the second UWB signal carries the ID number of the mobile measurement station and the timestamp and synchronous positioning information generated by it; The mobile measuring station is used to generate a second UWB signal using the second UWB data transmission module and send it to the reference measuring station each time the mobile measuring station establishes communication with the reference measuring station after being installed and fixed, and to receive the first UWB signal and the first sound signal with a timestamp sent by the reference measuring station, and further to timestamp the second sound signal generated when the high-voltage DC pulse signal applied to the power cable by the pulse generator is collected in real time by the second microphone; and The final location of the fault point in the power cable is determined using the data calculation module based on the second UWB signal and the second sound signal with a time stamp obtained after each active installation and fixation, and combined with the first UWB signal and the first sound signal with a time stamp sent by the reference measurement station each time.

2. The power cable fault trench positioning system based on UWB ranging and sound as claimed in claim 1, characterized in that: The data calculation module includes: A relative distance measurement submodule, for determining that the total number of times the mobile measurement station establishes communication with the reference measurement station after being installed and fixed is k, and based on the second UWB signal generated by the mobile measurement station after 1 to k times of installation and fixation and its corresponding first UWB signal received from the reference measurement station, and the first UWB signal generated by the reference measurement station 1 to k times and its corresponding second UWB signal received from the mobile measurement station, obtain k relative distances formed between the mobile measurement station and the reference measurement station after 1 to k times of installation and fixation, and further combine the preset coordinate position of the reference measurement station to obtain the coordinate position of the mobile measurement station after 1 to k times of installation and fixation; wherein k is a positive integer greater than 1; A sound signal decomposition submodule is used to intercept the second sound signal with a time stamp collected by the mobile measurement station at times 1 to k and the first sound signal with a time stamp collected by the reference measurement station at times 1 to k, so as to obtain the signal segments corresponding to the intercepted signal of the mobile measurement station and the reference measurement station at times 1 to k, and use a preset ensemble empirical mode decomposition (EEMD) algorithm to decompose the intercepted 2k signal segments to obtain the eigenmode function groups corresponding to the mobile measurement station and the reference measurement station at times 1 to k; A signal time difference processing submodule, for extracting the cable propagation path signals and atmospheric propagation path signals corresponding to the mobile measurement station and the reference measurement station at times 1 to k based on the eigenmode function groups of the mobile measurement station and the reference measurement station outputted by the sound signal decomposition submodule, so as to further obtain the time delay differences formed by the sound signals propagating in the power cable and the air at times 1 to k for the mobile measurement station and the reference measurement station; An air propagation speed acquisition submodule, for calculating k first propagation speeds of the sound signal propagating in the air based on the k relative distances between the mobile measuring station and the reference measuring station after 1 to k times of active installation and fixation outputted by the relative distance measurement submodule, and combining the atmospheric propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station at 1 to k times; A cable propagation speed acquisition submodule, for calculating k second propagation speeds of the sound signal when propagating in the power cable based on the k relative distances between the mobile measuring station and the reference measuring station after 1 to k times of active installation and fixation outputted by the relative distance measurement submodule, and combining the cable propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station at 1 to k times; The fault point positioning submodule is used to construct an objective function based on the time delay difference formed by the mobile measuring station when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position after being installed and fixed, and the time delay difference formed by the reference measuring station when the sound signal propagates in the power cable and the air 1 to k times and its coordinate position, and combined with the obtained k first propagation speeds of the sound signal when propagating in the air and the k second propagation speeds when propagating in the power cable, and use the particle swarm optimization algorithm and the Levenberg-Marquardt algorithm to find the optimal solution of the objective function, and the obtained optimal solution is output as the final position of the fault point in the power cable.

3. The power cable fault trench positioning system based on UWB ranging and sound as claimed in claim 2, characterized in that: The objective function is in, is the estimated position of the fault point in the power cable; p is the quantity to be estimated at the position of the fault point; the superscript j represents the number of measurements, and j=1, 2, ..., k; the subscript i represents the type of measurement site, i=1 represents the reference measurement site, and i=2 represents the mobile measurement site; represents the coordinate position of the i-th type measurement station at the jth time, represents the coordinate position of the reference measuring station at the jth time and they are defined as represents the coordinate position of the mobile measuring station at the jth time and they are defined as represents the relative distance between the mobile measuring station and the reference measuring station after the mobile measuring station is installed and fixed for the jth time; is the first propagation speed of the sound signal when it propagates in the air for the jth time; is the second propagation speed of the sound signal when it propagates in the jth power cable; represents the time delay difference caused by the sound signal propagating in the power cable and the air at the i-th measurement site for the jth time, represents the time delay difference formed by the reference measurement station when the sound signal propagates in the power cable and the air for the jth time, It represents the time delay difference formed by the mobile measuring station when the sound signal propagates in the power cable and the air for the jth time.

4. The power cable fault trench positioning system based on UWB ranging and sound as described in claim 3 is characterized in that: By formula Obtain the k-th corresponding eigenmode function group of the reference measurement station; and, by formula Get the k-th corresponding eigenmode function group of the mobile measuring station; where, From imf1 1,k , extracting the cable propagation path signal corresponding to the kth time at the reference measurement station; and from imf3 1,k ~imf5 1,k , extracting the atmospheric propagation path signal corresponding to the kth time at the reference measurement station; From imf1 2,k , extracting the cable propagation path signal corresponding to the kth time at the mobile measuring station; and from imf3 2,k ~imf5 2,k , extracting the atmospheric propagation path signal corresponding to the kth time at the mobile measurement station; m represents the maximum number of eigenmode function groups.

5. The power cable fault trench positioning system based on UWB ranging and sound as described in claim 4, characterized in that: By formula The time delay difference formed by the reference measuring station when the sound signal propagates in the power cable and the air for the kth time is calculated. and the time delay difference formed by the mobile measuring station when the sound signal propagates in the power cable and the air for the kth time in, Through the threshold method, we get represents the k-th time delay of the i-th type measurement station on the power cable propagation path, represents the k-th time delay of the reference measurement station on the power cable propagation path, represents the k-th time delay of the mobile measuring station on the power cable propagation path; represents the time delay of the kth measurement site of the i-th type on the air propagation path, represents the k-th time delay of the reference measurement station on the air propagation path, represents the k-th time delay of the mobile measuring station on the air propagation path; f s is a fixed threshold parameter.

6. The power cable fault trench positioning system based on UWB ranging and sound as described in claim 5, characterized in that: By formula Calculate the first propagation speed of the sound signal when it propagates in the air for the kth time; and, through the formula The second propagation velocity of the sound signal when it propagates in the power cable for the kth time is calculated.

7. The power cable fault trench positioning system based on UWB ranging and sound as claimed in claim 6, characterized in that: The k-th time delay of the reference measurement station on the air propagation path and the kth time delay of the mobile measuring station on the air propagation path They are all predicted by the Bayesian filtering method based on the previous k-1 time delays on the air propagation path.

8. A method for locating power cable faults in trenches based on UWB ranging and sound, characterized in that: It is implemented on the power cable fault trench positioning system based on UWB ranging and sound as described in claim 7, and the method comprises the following steps: The pulse generator periodically applies a high-voltage DC pulse signal to the power cable, so that when there is a fault point in the power cable, the fault point can be stimulated to emit a sound signal; The reference measurement station generates a first UWB signal, receives a second UWB signal sent by the mobile measurement station, and timestamps a first sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator based on real-time acquisition, and further sends the timestamped first sound signal together with the first UWB signal to the mobile measurement station; wherein the first UWB signal carries the ID number of the reference measurement station and the timestamp and synchronous positioning information generated by it; and the second UWB signal carries the ID number of the mobile measurement station and the timestamp and synchronous positioning information generated by it; When the mobile measuring station establishes communication with the reference measuring station after each active installation and fixation, it generates a second UWB signal and sends it to the reference measuring station, and timestamps the second sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator in real time, and further determines the final location of the fault point in the power cable by combining the first UWB signal sent by the reference measuring station and the first sound signal with the timestamp.

9. The method for locating a power cable fault in a trench based on UWB ranging and sound according to claim 8, characterized in that: The mobile measuring station generates a second UWB signal and sends it to the reference measuring station each time it establishes communication with the reference measuring station after each active installation and fixation, and timestamps the second sound signal generated when the power cable is applied with a high-voltage DC pulse signal by the pulse generator in real time, and further combines the first UWB signal sent by the reference measuring station and the first sound signal with the timestamp to determine the final position of the fault point in the power cable. The specific steps include: Determine that the total number of times the mobile measurement station establishes communication with the reference measurement station after being installed and fixed is k, and based on the second UWB signal generated by the mobile measurement station after 1 to k times of installation and fixation and its corresponding first UWB signal received from the reference measurement station, as well as the first UWB signal generated by the reference measurement station 1 to k times and its corresponding second UWB signal received from the mobile measurement station, obtain k relative distances formed between the mobile measurement station and the reference measurement station after 1 to k times of installation and fixation, and further combine the preset coordinate position of the reference measurement station to obtain the coordinate position of the mobile measurement station after 1 to k times of installation and fixation; wherein k is a positive integer greater than 1; The second sound signal with a time stamp collected by the mobile measuring station at times 1 to k and the first sound signal with a time stamp collected by the reference measuring station at times 1 to k are intercepted to obtain the signal segments corresponding to the mobile measuring station and the reference measuring station at times 1 to k, and the 2k intercepted signal segments are decomposed using a preset ensemble empirical mode decomposition (EEMD) algorithm to obtain the eigenmode function groups corresponding to the mobile measuring station and the reference measuring station at times 1 to k; Based on the eigenmode function groups of the mobile measuring station and the reference measuring station at 1 to k times, the cable propagation path signals and the atmospheric propagation path signals corresponding to the mobile measuring station and the reference measuring station at 1 to k times are extracted to further obtain the time delay difference formed by the sound signal propagating in the power cable and the air at 1 to k times of the mobile measuring station and the reference measuring station; Based on the k relative distances between the mobile measuring station and the reference measuring station after being installed and fixed for 1 to k times, and in combination with the atmospheric propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station for 1 to k times, k first propagation velocities of the sound signal propagating in the air are calculated; Based on k relative distances between the mobile measuring station and the reference measuring station after being installed and fixed for 1 to k times, and in combination with the cable propagation path signals correspondingly extracted by the mobile measuring station and the reference measuring station for 1 to k times, k second propagation velocities of the sound signal when propagating in the power cable are calculated; According to the time delay difference formed by the mobile measuring station 1 to k times when the sound signal propagates in the power cable and the air and its coordinate position after being installed and fixed, and the time delay difference formed by the reference measuring station 1 to k times when the sound signal propagates in the power cable and the air and its coordinate position, and combined with the obtained k first propagation speeds of the sound signal when propagating in the air and the k second propagation speeds when propagating in the power cable, an objective function is constructed, and the particle swarm optimization algorithm and the Levenberg-Marquardt algorithm are used to find the optimal solution of the objective function, and the obtained optimal solution is output as the final position of the fault point in the power cable.

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