A contact network short circuit detection and positioning device and method

Abstract

The embodiment of the present application applies for a contact network short-circuit detection and positioning device and method, the contact network includes an overhead contact line; the contact network short-circuit detection and positioning device includes: a measuring transformer installed at both ends of the overhead contact line; the frequency response of the measuring transformer is linear at least in the frequency range of 5kHz~10kHz, and the measuring transformer is used to collect parameters of the contact network, and the parameters include the voltage and line current at both ends of the contact network; an embedded system is arranged in the measuring transformer, and is used to transmit the parameters; a processing system is used to receive the parameters and determine the fault location point of the contact network based on the parameters. The contact network short-circuit detection and positioning device proposed in the present application enables the corresponding instrument measurement to have the characteristics of a dynamic mode when the contact network is short-circuited, which can significantly improve the accuracy and rapidity of fault detection and positioning, and reduce operating costs.

Description

Technical Field

[0001] The present application relates to the technical field of safety of overhead power supply systems, and in particular to an overhead short-circuit detection and positioning device and method. Background Art

[0002] In recent years, accidents have occurred frequently due to foreign objects such as kites and dust nets hanging on the railway power supply contact network, causing power outages or abnormal power supply to the contact network, delaying the normal operation of trains. These consequences are catastrophic, often causing huge economic losses and negative social effects.

[0003] For short-circuit faults caused by foreign object intrusion in the contact network, the existing methods have different applicable scopes and different accuracy when determining the distance to the fault point. The main methods include fault recording analysis method, traveling wave method and impedance method. The voltage and current are measured by inductive current transformers and voltage transformers, which have the problems of low accuracy or high cost.

[0004] During the measurement process, when the inductive current transformer exceeds 120% of its rated current, the measurement accuracy is uncertain. In addition, the core material of the inductive current transformer has a nonlinear magnetization curve, which makes the initial data ambiguous and the short-circuit current value uncertain. The measured current can only be estimated, resulting in low accuracy in measuring short-circuit current. The accuracy level of voltage transformers corresponds to a voltage range of 80-120% of the rated voltage. There is no data on their operation in dynamic mode, which also reduces the accuracy of existing fault detection and location methods. Summary of the invention

[0005] In order to solve the above technical problems or at least partially solve the above technical problems, the present application provides a contact network short circuit detection and positioning device and method.

[0006] In a first aspect, the present application provides a contact network short-circuit detection and positioning device, wherein the contact network includes an overhead contact line; the contact network short-circuit detection and positioning device includes:

[0007] A measuring transformer is installed at the head end and the tail end of the overhead contact line; the frequency response of the measuring transformer is linear at least in the frequency range of 5kHz to 10kHz, and the measuring transformer is used to collect the measured parameters of the contact network, and the measured parameters include the head end voltage, the tail end voltage and the line current of the contact network;

[0008] An embedded system, arranged in the measuring transformer, for transmitting the measured parameters;

[0009] A processing system is used to receive the measured parameters and determine the fault location point of the contact network based on the measured parameters.

[0010] In a second aspect, the present application provides a contact network short circuit detection and positioning method, which is performed based on a contact network short circuit detection and positioning device, wherein the contact network short circuit detection and positioning device includes a measuring transformer, an embedded system, and a processing system; the contact network short circuit detection and positioning method includes:

[0011] Obtaining measured parameters of the overhead contact network, the measured parameters including the head-end voltage, tail-end voltage and line current of the overhead contact network, the measured parameters being obtained based on the measurement of the overhead contact network to be measured by the measuring transformer in a steady-state mode, the measuring transformer being installed at the head-end and tail-end of the overhead contact line, and the frequency response being linear in a frequency range of at least 5kHz to 10kHz;

[0012] Based on the measured parameters, a fault location point of the contact network is determined.

[0013] Optionally, the obtaining of measured parameters of the contact network includes:

[0014] A first type of measured parameters of the contact network in a normal state are obtained, and a second type of measured parameters of the contact network in a short-circuit state are obtained.

[0015] Optionally, determining the fault location point of the contact network based on the measured parameters includes:

[0016] Based on the first type of measured parameters, determining the parameters of the overhead contact line;

[0017] Based on the second type of measured parameters, determining operating parameters under the short-circuit state;

[0018] Based on the operating parameters under the short-circuit state and the parameters of the overhead contact line, a fault location point of the contact network is determined.

[0019] Optionally, determining the parameters of the overhead contact line based on the first type of measured parameters includes:

[0020] Based on the first type of measured parameters, determining actual line parameters; the actual line parameters include line impedance, line resistance and line inductance;

[0021] Based on the actual line parameters, the parameters of the overhead contact line are determined; the parameters of the overhead contact line include unit resistance and unit inductance.

[0022] Optionally, determining actual line parameters based on the first type of measured parameters includes:

[0023] Based on the head-end voltage, tail-end voltage and line current of the contact network in a normal state, the corresponding root mean square values ​​are calculated respectively, as well as the first phase and the second phase; wherein the root mean square value includes the root mean square value of the head-end voltage, the root mean square value of the tail-end voltage and the root mean square value of the line current; the first phase is the phase between the line current and the head-end voltage, and the second phase is the phase between the line current and the tail-end voltage;

[0024] Based on the RMS value, the line impedance is calculated using Formula 1; wherein Formula 1 is:

[0025] Formula 1

[0026] Where Z represents the line impedance, represents the RMS value of the voltage at the first end, represents the RMS value of the tail voltage, Represents the RMS value of the line current;

[0027] Based on the line impedance and the second phase, the line resistance is calculated using Formula 2; wherein Formula 2 is:

[0028] Formula 2

[0029] Where R represents the line resistance, φ 2 Represents the second phase;

[0030] Based on the line resistance and the second phase, the line inductance is calculated using Formula 3; wherein Formula 3 is:

[0031] Formula 3

[0032] Where X represents the line inductance;

[0033] The step of determining the parameters of the overhead contact line based on the actual line parameters comprises:

[0034] Based on the line resistance and in combination with the line length, the unit resistance is calculated using Formula 4; wherein Formula 4 is:

[0035] Formula 4

[0036] in, r 0 Represents unit resistance, l line Represents the line length;

[0037] Based on the line inductance and in combination with the line length, the unit inductance is calculated using Formula 5; wherein Formula 5 is:

[0038] Formula 5

[0039] in, x 0 Represents unit inductance.

[0040] Optionally, determining the operating parameters under the short-circuit state based on the second-category measured parameters includes:

[0041] Based on the second type of measured parameters, solving the unknown parameters in the expression formula of the short-circuit current at any point under the short-circuit state and the expression formula of the voltage at the head end of the line, and obtaining the voltage amplitude and current amplitude under the short-circuit state;

[0042] Based on the voltage amplitude and the current amplitude, the line impedance value up to the point where the short circuit occurs is calculated using Formula 8;

[0043] Among them, the expression formula of short-circuit current at any point under short-circuit state is:

[0044] Formula 6

[0045] in, i 1 (t) Represents the short-circuit current at any point in the short-circuit state, I m represents the current amplitude, ω represents the angular frequency, α represents the initial angle of the current, Φs.c. represents the phase angle of the short-circuit impedance, i a (0) represents the initial value of the non-periodic component of the short-circuit current, Ta represents the time constant of the non-periodic component, and t represents the value at a certain moment;

[0046] The voltage expression formula of the line head end in the short circuit state is:

[0047] Formula 7

[0048] in, u 1 (t) Represents the voltage at the beginning of the line under short-circuit condition, U m represents the voltage amplitude, ω represents the angular frequency, β represents the initial voltage phase, Φ U Represents the initial angle of the voltage, u a (0) represents the initial value of the non-periodic voltage component, Tu represents the time constant of the non-periodic component, and t represents the value at a certain moment;

[0049] The formula 8 is:

[0050] Formula 8

[0051] Among them, Z S.C. Represents the line impedance value up to the point where the short circuit occurs.

[0052] Optionally, based on the second type of measured parameters, solving the unknown parameters in the expression formula of the short-circuit current at any point in the short-circuit state and the expression formula of the voltage at the first end of the line to obtain the voltage amplitude and the current amplitude in the short-circuit state includes:

[0053] Select at least 5 first-end voltages at different times from the second type of measured parameters, substitute them into the formula 7, and combine them to obtain a first set of equations;

[0054] Solving the first set of equations to obtain a voltage amplitude under a short-circuit state;

[0055] as well as

[0056] Select at least 5 line currents at different times from the second type of measured parameters, substitute them into the formula 6, and combine them to obtain a second set of equations;

[0057] The second set of equations is solved to obtain the current amplitude under the short-circuit state.

[0058] Optionally, determining the fault location point of the contact network based on the operating condition parameters in the short-circuit state and the parameters of the overhead contact line includes:

[0059] Determining the distance to the point where the short circuit occurs based on the operating parameters under the short circuit state and the parameters of the overhead contact line;

[0060] Based on the distance, the fault location point is determined.

[0061] Optionally, determining the distance to the point where the short circuit occurs includes:

[0062] The distance to the point where the short circuit occurs is calculated using Formula 9; where Formula 9 is:

[0063]

[0064] in, l S.C. Represents the distance to the point where the short circuit occurs; Z S.C. represents the line impedance value up to the point where the short circuit occurs, which is the operating condition parameter; r 0 Represents unit resistance, x 0 represents unit inductance, which are parameters of the overhead contact line.

[0065] Compared with the prior art, the technical solution provided by this application has the following advantages:

[0066] The contact network short-circuit detection and positioning device proposed in the present application collects the parameters of the contact network to be tested through the measuring transformer, and the parameters include the voltage and line current at both ends of the contact network to be tested, and then transmits the parameters through the embedded system inside the measuring transformer, and finally the processing system receives the parameters and determines the fault location point of the contact network to be tested based on the parameters. The contact network short-circuit detection and positioning device proposed in the present application enables the corresponding instrument to measure the real-time collection of the parameters of the contact network to be tested through the measuring transformer when the contact network is short-circuited, and then transmits the parameters through the embedded system inside the measuring transformer, and finally the processing system receives the parameters and determines the fault location point of the contact network to be tested based on the parameters. Therefore, it has the characteristics of a dynamic mode, which can significantly improve the accuracy and speed of fault detection and positioning. At the same time, the fault detection and positioning method proposed in the present invention has a lower operating cost, and can effectively reduce the fault time of the contact network caused by foreign matter, and the linear frequency response characteristics can effectively improve the accuracy of the fault detection and positioning method. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0068] In order to more clearly illustrate the embodiments of the present application 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0069] Figure 1 A schematic diagram of the structure of a contact network short-circuit detection and positioning device provided in an embodiment of the present application;

[0070] Figure 2 A schematic diagram of the installation position of a contact network short-circuit detection and positioning device provided in an embodiment of the present application;

[0071] Figure 3 A schematic diagram of the installation principle of a contact network short-circuit detection and positioning device provided in an embodiment of the present application;

[0072] Figure 4 A schematic diagram of a flow chart of a method for detecting and locating a short circuit in a contact network provided in an embodiment of the present application;

[0073] Figure 5 A steady-state equivalent circuit diagram of an overhead contact line provided in an embodiment of the present application;

[0074] Figure 6 An overhead contact line steady-state vector diagram provided in an embodiment of the present application. DETAILED DESCRIPTION

[0075] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0076] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only part of the embodiments of the present application, rather than all of the embodiments.

[0077] Before introducing the contact network short-circuit detection and positioning device and method proposed in this scheme, the problems existing in the current contact network short-circuit detection and positioning device and method and the solutions of the prior art are first introduced to make it easier to understand this scheme later.

[0078] In recent years, accidents have occurred frequently due to foreign objects such as kites and dust nets hanging on the railway power supply contact network, causing power outages or abnormal power supply to the contact network, delaying the normal operation of trains, and even causing contact network disconnection accidents. These consequences are catastrophic and often cause huge economic losses and negative social effects.

[0079] For short-circuit faults caused by foreign body intrusion in the contact network, the existing methods have different applicable scopes and different accuracy in determining the distance of the fault point. The main methods include fault recording analysis method, traveling wave method and impedance method. The existing methods will be introduced in detail below.

[0080] First, the fault recording analysis method is introduced in detail. The fault recording analysis method is a general method that lists the distance measurement equation according to the system parameters and the voltage and current of the distance measurement point when a fault occurs in the transmission line, and then analyzes and calculates it to find the distance between the fault point and the distance measurement point. With the development of computer technology and artificial intelligence technology, the fault recording analysis method can be quickly completed by automated equipment. However, this method will be affected by the system impedance and the transition impedance of the fault point, resulting in a decrease in the accuracy of fault distance measurement.

[0081] Next, the traveling wave method is introduced in detail. The traveling wave method is a fault distance measurement method based on the principle of traveling wave transmission. When a fault occurs in the distribution network, a traveling wave will be generated at the fault point and propagate to both ends of the line. The traveling wave method calculates the fault distance by detecting the time difference between the traveling wave reaching both ends of the line. The advantage of the traveling wave method is that it has high ranging accuracy and is not affected by line parameters, system operation mode and fault type. In addition, the traveling wave method can also be used to determine the direction of the fault point, which helps to quickly locate the fault area. However, the implementation of the traveling wave method requires high-precision traveling wave detection equipment and complex algorithm support, which is costly. At the same time, the traveling wave may be affected by factors such as attenuation, dispersion and distortion during transmission, resulting in reduced ranging accuracy.

[0082] Finally, the impedance method is introduced in detail. The impedance method is a fault distance measurement method based on the relationship between line impedance and fault distance. When a fault occurs in the distribution network, the voltage and current at the fault point will change, resulting in a change in line impedance. The impedance method calculates the line impedance by measuring the voltage and current at the fault point, and then infers the fault distance. The advantages of the impedance method are that its principle is simple, easy to implement, and has low requirements for equipment. However, the distance measurement accuracy of the impedance method is affected by many factors, such as line parameters, system operation mode, fault type, etc.

[0083] Through the above description of the existing short-circuit fault analysis method, inductive current transformers and voltage transformers are used when measuring voltage and current, which may cause problems of low accuracy or high cost. Because during the measurement process, when the inductive current transformer exceeds 120% of its rated current, there is uncertainty in the measurement accuracy, and the core material of the inductive current transformer has a nonlinear magnetization curve, which makes the initial data fuzzy and the short-circuit current value uncertain. The measured current can only be estimated, resulting in low accuracy in measuring short-circuit current. The accuracy level of the voltage transformer corresponds to a voltage range of 80-120% of the rated voltage, and there is no data on their operation in dynamic mode, which also reduces the accuracy of existing fault detection and positioning methods.

[0084] In order to solve the problems of low accuracy or high cost of the contact network short-circuit fault detection equipment in the prior art, and the lack of data running in dynamic mode, which reduces the accuracy of the existing fault detection and positioning methods, this solution provides a contact network short-circuit detection and positioning device and method, which can effectively solve the problems in the prior art. The following text first introduces the contact network short-circuit detection and positioning device provided by this solution.

[0085] For example, Figure 1 A schematic diagram of the structure of a contact network short circuit detection and positioning device provided in an embodiment of the present application. Figure 1As shown, the contact network short circuit detection and positioning device provided in the embodiment of the present application includes a measuring transformer 101, an embedded system 102 and a processing system 103.

[0086] The contact network includes an overhead contact line 104. The measuring transformer 101 is installed at both ends of the overhead contact line 104. Figure 2 or Figure 3 As shown, the frequency response of the measuring transformer 101 is linear at least in the frequency range of 5kHz to 10kHz, and the measuring transformer 101 is used to collect the parameters of the contact network, including the voltage at both ends of the contact network and the line current. Among them, 105 represents an insulator, and 106 represents a pole tower, which is used to erect the overhead contact line 104.

[0087] The embedded system 102 is arranged in the measuring transformer 101 and is used to transmit parameters. The processing system 103 is used to receive the parameters and determine the fault location point of the contact network based on the parameters. For example, the processing system 103 can be arranged in the measuring transformer 101, such as Figure 1 As shown; in other embodiments, the processing system 103 may also be disposed outside the measuring transformer 101 and be communicatively connected to the measuring transformer 101, which is not limited here.

[0088] In some embodiments, an inductive current transformer and a voltage transformer are installed on the overhead contact line itself for measuring and protecting the overhead contact line. When the contact network short-circuit detection and positioning device provided in the embodiment of the present application is installed on the overhead contact line, the measuring transformer is installed at both ends of the overhead contact line for collecting parameters of the contact network, including the voltage and line current at both ends of the contact network.

[0089] For example, reference Figure 2 and Figure 3 , the inductive current transformer CT, the inductive voltage transformer VT and the overhead contact network short-circuit detection and positioning equipment UMT are all connected to the overhead contact network line. Among them, the inductive current transformer CT and the inductive voltage transformer VT are installed in the overhead contact network line to measure data and protect the line; the overhead contact network short-circuit detection and positioning equipment UMT is the overhead contact network short-circuit detection and positioning equipment provided in the embodiment of the present application, which is installed at both ends of the overhead contact line to collect the parameters of the overhead contact network. Exemplarily, Figure 3 China-Israel u 1 (t) , u 2 (t) and i(t) The first-end voltage, the tail-end voltage and the line current are shown respectively.

[0090] In some embodiments, the measuring transformer can measure up to 31st harmonics when measuring current and line-to-ground voltage. The advantage for fault detection and location problem is that no external power supply is required and data transmission is carried out through a special embedded system. Based on this device, a flexible system needs to be established to measure the contact network parameters and determine the fault location point of the contact network.

[0091] The contact network short-circuit detection and positioning device proposed in the embodiment of the present application collects parameters of the contact network to be tested by measuring the transformer, the parameters including the voltage and line current at both ends of the contact network to be tested, and then transmits the parameters through the embedded system inside the measuring transformer. Finally, the processing system receives the parameters and determines the fault location point of the contact network to be tested based on the parameters.

[0092] Therefore, the contact network short-circuit detection and positioning device provided in the embodiment of the present application can be linear in a wider frequency range, and has a specific system for data transmission. The contact network short-circuit detection and positioning device is installed at both ends of the contact network to be tested to measure the parameters of the overhead contact line, and thereby determine the fault location point of the overhead contact line. Moreover, when using the contact network short-circuit detection and positioning device provided in the embodiment of the present application, the corresponding instrument measurement has the characteristics of a dynamic mode when the contact network is short-circuited, which can significantly improve the accuracy and speed of fault detection and positioning. At the same time, the fault detection and positioning method proposed by the present invention has a lower operating cost, and can effectively reduce the fault time of the contact network caused by foreign matter, and the linear frequency response characteristics can effectively improve the accuracy of the fault detection and positioning method.

[0093] Based on the contact network short-circuit detection and positioning equipment, an embodiment of the present application also provides a contact network short-circuit detection and positioning method for determining a fault location point of the contact network.

[0094] It should be noted that in some implementations, the contact wire, that is, the contact network conductor, is divided into power supply sections, and the length of a power supply section can be 20 kilometers to 30 kilometers, and electrical insulation isolation is set between adjacent power supply sections. Among them, when the train passes through the electrical insulation isolation between adjacent power supply sections, the pantograph on the top of the train will form conduction between the two contact wires between the adjacent power supply sections, resulting in the effect of temporarily adding load (i.e. short circuit); for this process, the positioning method provided by the embodiment of the present disclosure can be verified multiple times a day, and the positioning data obtained by the positioning method provided by the embodiment of the present disclosure can be compared with the on-board positioning data of the train to form a correlation relationship, so that the on-board positioning data of the train can be used as reference data, and the positioning error of the positioning method provided by the embodiment of the present disclosure can be corrected through the large amount of on-board positioning data of the train collected, so as to achieve higher positioning accuracy.

[0095] For example, Figure 4The present invention provides a schematic flow chart of a method for detecting and locating a short circuit in a contact network. The method is performed based on a short circuit detection and locating device for the contact network. The short circuit detection and locating device for the contact network includes a measuring transformer, an embedded system, and a processing system. For details, please refer to the above text. Figure 4 As shown, the contact network short circuit detection and positioning method may include the following steps:

[0096] Step 401: Obtain measured parameters of the contact network, including the head-end voltage, tail-end voltage and line current of the contact network, and the measured parameters are obtained based on the measurement of the contact network to be measured by a measuring transformer in a steady-state mode. The measuring transformer is installed at the head and tail ends of the overhead contact line, and the frequency response is linear at least in the frequency range of 5kHz~10kHz.

[0097] In some embodiments, in step 401, obtaining measured parameters of the contact network may specifically include: obtaining first-type measured parameters of the contact network in a normal state, and obtaining second-type measured parameters of the contact network in a short-circuit state. This facilitates determining the contact network parameters itself in combination with the measured parameters in a normal state, and locating the short-circuit fault point in combination with the measured parameters in a short-circuit state.

[0098] Step 402: Determine the fault location point of the overhead line based on the measured parameters.

[0099] Exemplarily, this step may include performing data processing on the above-mentioned measured parameters to determine the fault location of the contact network, that is, to determine the fault location point.

[0100] The contact network short-circuit detection and positioning method proposed in the embodiment of the present application obtains the parameters of the contact network based on the contact network short-circuit detection and positioning equipment. The parameters are obtained based on the measurement of the contact network to be measured by the measuring transformer in the steady-state mode. The parameters include the voltage and line current at the two ends of the contact network to be measured. The parameters are then transmitted by the embedded system inside the measuring transformer. Finally, the processing system receives the parameters and determines the fault location point of the contact network to be measured based on the parameters.

[0101] Therefore, the contact network short-circuit detection and positioning equipment proposed in the embodiment of the present application enables the corresponding instrument measurement to have the characteristics of a dynamic mode when the contact network is short-circuited, which can significantly improve the accuracy and speed of fault detection and positioning. At the same time, the fault detection and positioning method proposed in the present invention has lower operating costs, and can effectively reduce the fault time of the contact network caused by foreign objects, and the linear frequency response characteristics can effectively improve the accuracy of the fault detection and positioning method.

[0102] In step 402, the fault location point of the contact network is determined based on the measured parameters, including: determining the parameters of the overhead contact line based on the first type of measured parameters; determining the operating parameters under the short-circuit state based on the second type of measured parameters; determining the fault location point of the contact network based on the operating parameters under the short-circuit state and the parameters of the overhead contact line.

[0103] In a specific implementation, the parameters of the overhead contact line are determined based on the first type of measured parameters, including: determining the actual line parameters based on the first type of measured parameters; the actual line parameters include line impedance, line resistance and line inductance; determining the parameters of the overhead contact line based on the actual line parameters; the parameters of the overhead contact line include unit resistance and unit inductance. Determining the actual line parameters based on the first type of measured parameters includes: calculating the corresponding root mean square values ​​based on the head end voltage, tail end voltage and line current of the contact network in a normal state, and calculating the first phase and the second phase; wherein the root mean square value includes the root mean square value of the head end voltage, the root mean square value of the tail end voltage and the root mean square value of the line current; the first phase is the phase between the line current and the head end voltage, and the second phase is the phase between the line current and the tail end voltage.

[0104] When the overhead contact line is measured in steady-state mode based on the contact network short-circuit detection and positioning equipment, the voltage instantaneous value u at both ends of the overhead contact line is measured based on the contact network short-circuit detection and positioning equipment. ph1 (t) (i.e. u 1 (t) )、u ph2 (t) (i.e. u 2 (t) ) and line current i(t), determine the RMS value of the voltage at both ends of the contact network to be tested , and the line current RMS value , and the phase between the current and voltage at both ends of the overhead contact line Φ 1 (t) and Φ 2 (t).

[0105] For example, Figure 5 A steady-state equivalent circuit diagram of an overhead contact line provided in an embodiment of the present application, Figure 6 An overhead contact line steady-state vector diagram provided in an embodiment of the present application.

[0106] Combination Figure 5 and Figure 6 , based on the contact network short-circuit detection and positioning equipment, the overhead contact line is measured in steady-state mode to determine the unit resistance value and unit inductance value of the overhead contact line.

[0107] Based on the RMS value, the line impedance is calculated using Equation 1, where Equation 1 is:

[0108] Formula 1

[0109] Where Z represents the line impedance, represents the RMS value of the voltage at the first end, represents the RMS value of the tail voltage, Represents the RMS value of the line current;

[0110] Based on the line impedance and the second phase, the line resistance is calculated using Formula 2; where Formula 2 is:

[0111] Formula 2

[0112] Where R represents the line resistance, φ 2 Represents the second phase;

[0113] Based on the line resistance and the second phase, the line inductance is calculated using Equation 3; where Equation 3 is:

[0114] Formula 3

[0115] Where X represents the line inductance;

[0116] Based on the actual line parameters, determine the parameters of the overhead contact line, including:

[0117] Based on the line resistance and the line length, the unit resistance is calculated using Formula 4; where Formula 4 is:

[0118] Formula 4

[0119] in, r 0 Represents unit resistance, l line Represents the line length;

[0120] Based on the line inductance and line length, the unit inductance is calculated using Formula 5; where Formula 5 is:

[0121] Formula 5

[0122] in, x 0 Represents unit inductance.

[0123] In some embodiments, when determining the unit resistance r of the contact line 0 With unit inductance x 0If the temperature factor needs to be considered, the corresponding temperature coefficient needs to be added for correction.

[0124] Therefore, using the overhead contact network short-circuit detection and positioning equipment provided in the embodiment of the present application can obtain more accurate parameter values ​​of the overhead contact network equivalent circuit than using traditional inductive current transformers and voltage transformers.

[0125] Through the above-mentioned measurement of the overhead contact line in the steady-state mode, when a short circuit occurs in the overhead contact line, the unit resistance and inductance of the overhead contact line can be used; when a short circuit occurs, the voltage amplitude and current amplitude are calculated by combining multiple short-circuit current and line head voltage expressions, and the line impedance value up to the point where the short circuit occurs is calculated. Finally, the distance to the short-circuit point is calculated through the unit resistance and inductance of the contact line.

[0126] Based on the second type of measured parameters, the expression formula of the short-circuit current at any point under the short-circuit state and the unknown parameters in the expression formula of the voltage at the head end of the line are solved to obtain the voltage amplitude and current amplitude under the short-circuit state; based on the voltage amplitude and current amplitude, Formula 8 is used to calculate the line impedance value up to the point where the short circuit occurs.

[0127] Among them, the expression formula of short-circuit current at any point under short-circuit state is:

[0128] Formula 6

[0129] in, i 1 (t) represents the short-circuit current at any point under the short-circuit condition, ω represents the angular frequency, I m represents the current amplitude, α represents the initial angle of the current, Φs.c. represents the phase angle of the short-circuit impedance, i a (0) represents the initial value of the non-periodic component of the short-circuit current, Ta represents the time constant of the non-periodic component, and t represents the value at a certain moment;

[0130] The voltage expression formula of the line head end in the short circuit state is:

[0131] Formula 7

[0132] in, u 1 (t) Represents the voltage at the beginning of the line under short-circuit condition, U m represents the voltage amplitude, ω represents the angular frequency, β represents the initial voltage phase, Φ U Represents the initial angle of the voltage, u a (0) represents the initial value of the non-periodic voltage component, Tu represents the time constant of the non-periodic component, and t represents the value at a certain moment;

[0133] Formula 8 is:

[0134] Formula 8

[0135] Among them, Z S.C. Represents the line impedance value up to the point where the short circuit occurs.

[0136] Based on the second type of measured parameters, the expression formula of the short-circuit current at any point in the short-circuit state and the unknown parameters in the expression formula of the line head end voltage are solved to obtain the voltage amplitude and current amplitude in the short-circuit state, including: selecting the head end voltage at at least 5 different times from the second type of measured parameters, substituting them into formula 7, and combining to obtain the first set of equations; solving the first set of equations to obtain the voltage amplitude in the short-circuit state; and selecting the line current at at least 5 different times from the second type of measured parameters, substituting them into formula 6, and combining to obtain the second set of equations; solving the second set of equations to obtain the current amplitude in the short-circuit state.

[0137] In a specific implementation, five moments are selected and substituted into Formula 6 to form a set of equations 1 consisting of five expressions; these five moments can be substituted into Formula 7 to form a set of equations 2 consisting of five expressions to calculate the voltage amplitude Um and the current amplitude Im;

[0138] In some embodiments, five moments t = 0.005s, 0.010s, 0.015s, 0.020s, and 0.025s are selected and substituted into Formula 6 to form a set of equations 1 consisting of five expressions:

[0139] Equation 1

[0140] Select t = 0.005s, 0.010s, 0.015s, 0.020s, 0.025s and substitute them into Formula 7 to form Equation Group 2 consisting of five expressions:

[0141] Equation 2

[0142] By solving equation group 1, the five unknown quantities can be calculated to obtain the current amplitude I m ; By solving equation group 2, the five unknown quantities can also be calculated, thus obtaining the voltage amplitude U m In the embodiment of the present application, the fault may be a metal foreign body fault or other types of short circuit faults, which are not limited here.

[0143] In some embodiments, the selection of time is not limited to the five times t = 0.005s, 0.010s, 0.015s, 0.020s, and 0.025s, and any other five different time points can be selected according to the requirements of the detection and positioning method, which is not limited here.

[0144] When the voltage amplitude U is obtained under the short-circuit state of the contact network to be tested m and the current amplitude I m Afterwards, based on the voltage amplitude U under the short-circuit state of the contact network to be tested m and the current amplitude I m , the line impedance value up to the point where the short circuit occurs can be calculated and determined.

[0145] In some embodiments, the fault location point of the contact network is determined based on the operating parameters under the short-circuit state and the parameters of the overhead contact line. Specifically, it may include: determining the distance to the point where the short circuit occurs based on the operating parameters under the short-circuit state and the parameters of the overhead contact line; determining the fault location point based on the distance.

[0146] Wherein, determining the distance to the point where the short circuit occurs may specifically include: using Formula 9 to calculate the distance to the point where the short circuit occurs; wherein Formula 9 is:

[0147]

[0148] in, l S.C. Represents the distance to the point where the short circuit occurs; Z S.C. Represents the line impedance value up to the point where the short circuit occurs, which is the operating condition parameter; r 0 Represents unit resistance, x 0 Represents unit inductance, all of which are parameters of overhead contact lines.

[0149] The contact network short-circuit detection and positioning method provided in the embodiment of the present application is based on the contact network short-circuit detection and positioning equipment. By performing steady-state measurement on the overhead contact line, the impedance value, resistance value and inductance value of the actual line are calculated, and then the unit resistance value and inductance value of the contact line are calculated; when a short circuit occurs, the voltage amplitude and current amplitude are calculated by combining multiple short-circuit current and line head end voltage expressions, and the line impedance value up to the point where the short circuit occurs is calculated, and finally the distance to the short-circuit point is calculated by the unit resistance value and inductance value of the contact line.

[0150] Therefore, the contact network short-circuit detection and positioning method provided in the embodiment of the present application enables the corresponding instrument measurement to have the characteristics of a dynamic mode when the contact network is short-circuited, which can significantly improve the accuracy and speed of fault detection and positioning. At the same time, the fault detection and positioning method proposed in the present invention has lower operating costs, and can effectively reduce the fault time of the contact network caused by foreign objects, and the linear frequency response characteristics can effectively improve the accuracy of the fault detection and positioning method.

[0151] In some embodiments, a contact network short-circuit detection and positioning device and method provided in the embodiments of the present application can measure short-circuit currents within a wider frequency range and can also accurately obtain measurement result values.

[0152] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0153] The above is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features applied for herein.

Claims

1. A method for detecting and locating a short circuit in a contact network, characterized in that: Executed based on a contact network short-circuit detection and positioning device, the contact network short-circuit detection and positioning device includes a measuring transformer, an embedded system and a processing system; The contact network short circuit detection and positioning method comprises: Obtaining measured parameters of the contact network, the measured parameters including the head-end voltage, tail-end voltage and line current of the contact network, the measured parameters being obtained based on the measurement of the contact network to be measured by the measuring transformer in a steady-state mode, the measuring transformer being installed at the head-end and tail-end of the overhead contact line, and the frequency response being linear in a frequency range of at least 5kHz to 10kHz; Based on the measured parameters, determining the fault location point of the contact network; The obtaining of the measured parameters of the contact network comprises: Acquiring first-type measured parameters of the contact network in a normal state, and acquiring second-type measured parameters of the contact network in a short-circuit state; The determining of the fault location point of the contact network based on the measured parameters includes: Based on the first type of measured parameters, determining the parameters of the overhead contact line; Based on the second type of measured parameters, determining operating parameters under the short-circuit state; Determining a fault location point of the contact network based on the operating parameters under the short-circuit state and the parameters of the overhead contact line; The step of determining the parameters of the overhead contact line based on the first type of measured parameters includes: Based on the first type of measured parameters, determining actual line parameters; the actual line parameters include line impedance, line resistance and line inductance; Based on the actual line parameters, determining the parameters of the overhead contact line; the parameters of the overhead contact line include unit resistance and unit inductance; The determining the actual line parameters based on the first type of measured parameters includes: Based on the head-end voltage, tail-end voltage and line current of the contact network in a normal state, the corresponding root mean square values ​​are calculated respectively, as well as the first phase and the second phase; wherein the root mean square value includes the root mean square value of the head-end voltage, the root mean square value of the tail-end voltage and the root mean square value of the line current; the first phase is the phase between the line current and the head-end voltage, and the second phase is the phase between the line current and the tail-end voltage; Based on the RMS value, the line impedance is calculated using Formula 1; wherein Formula 1 is: Formula 1 Where Z represents the line impedance, represents the RMS value of the voltage at the first end, represents the RMS value of the tail voltage, represents the RMS value of the line current; Based on the line impedance and the second phase, the line resistance is calculated using Formula 2; wherein Formula 2 is: Formula 2 Where R represents the line resistance, φ 2 represents the second phase; Based on the line resistance and the second phase, the line inductance is calculated using Formula 3; wherein Formula 3 is: Formula 3 Where X represents the line inductance; The step of determining the parameters of the overhead contact line based on the actual line parameters comprises: Based on the line resistance and in combination with the line length, the unit resistance is calculated using Formula 4; wherein Formula 4 is: Equation 4 in, r 0 represents unit resistance, l line Represents the line length; Based on the line inductance and in combination with the line length, the unit inductance is calculated using Formula 5; wherein Formula 5 is: Formula 5 in, x 0 represents unit inductance.

2. The contact network short circuit detection and positioning method according to claim 1, characterized in that: Based on the second type of measured parameters, the operating parameters under the short circuit state are determined, including: Based on the second type of measured parameters, solving the unknown parameters in the expression formula of the short-circuit current at any point under the short-circuit state and the expression formula of the voltage at the head end of the line, and obtaining the voltage amplitude and current amplitude under the short-circuit state; Based on the voltage amplitude and the current amplitude, the line impedance value up to the point where the short circuit occurs is calculated using Formula 8; Among them, the expression formula of short-circuit current at any point under short-circuit state is: Formula 6 in, i 1 (t) Represents the short-circuit current at any point in the short-circuit state, I m represents the current amplitude, ω represents the angular frequency, α represents the initial angle of the current, Φs.c. represents the phase angle of the short-circuit impedance, i a (0) represents the initial value of the non-periodic component of the short-circuit current, Ta represents the time constant of the non-periodic component, and t represents the value at a certain moment; The voltage expression formula of the line head end in the short circuit state is: Formula 7 in, u 1 (t) Represents the voltage at the beginning of the line under short-circuit condition, U m represents the voltage amplitude, ω represents the angular frequency, β represents the initial voltage phase, Φ U Represents the initial angle of the voltage, u a (0) represents the initial value of the non-periodic voltage component, Tu represents the time constant of the non-periodic component, and t represents the value at a certain moment; The formula 8 is: Formula 8 Among them, Z S.C. Represents the line impedance value up to the point where the short circuit occurs.

3. The contact network short circuit detection and positioning method according to claim 2 is characterized in that: The method of solving the unknown parameters in the expression formula of the short-circuit current at any point under the short-circuit state and the expression formula of the voltage at the first end of the line based on the second type of measured parameters, and obtaining the voltage amplitude and current amplitude under the short-circuit state, includes: Select at least 5 first-end voltages at different times from the second type of measured parameters, substitute them into the formula 7, and combine them to obtain a first set of equations; Solving the first set of equations to obtain a voltage amplitude under a short-circuit state; as well as Select at least 5 line currents at different times from the second type of measured parameters, substitute them into the formula 6, and combine them to obtain a second set of equations; The second set of equations is solved to obtain the current amplitude under the short-circuit state.

4. The contact network short circuit detection and positioning method according to claim 1, characterized in that: The determining of the fault location point of the contact network based on the operating condition parameters in the short-circuit state and the parameters of the overhead contact line comprises: Determining the distance to the point where the short circuit occurs based on the operating parameters under the short circuit state and the parameters of the overhead contact line; Based on the distance, the fault location point is determined.

5. The contact network short circuit detection and positioning method according to claim 4, characterized in that: The determining of the distance to the point where the short circuit occurs comprises: The distance to the point where the short circuit occurs is calculated using Formula 9; where Formula 9 is: in, l S.C. Represents the distance to the point where the short circuit occurs; Z S.C. represents the line impedance value up to the point where the short circuit occurs, which is the operating condition parameter; r 0 represents unit resistance, x 0 represents unit inductance, which are the parameters of the overhead contact line.

6. A contact network short circuit detection and positioning device, characterized in that: Used to implement the contact network short-circuit detection and positioning method according to any one of claims 1 to 5; the contact network includes an overhead contact line; the contact network short-circuit detection and positioning device includes: A measuring transformer is installed at the head end and the tail end of the overhead contact line; the frequency response of the measuring transformer is linear at least in the frequency range of 5kHz to 10kHz, and the measuring transformer is used to collect the measured parameters of the contact network, and the measured parameters include the head end voltage, the tail end voltage and the line current of the contact network; An embedded system, arranged in the measuring transformer, for transmitting the measured parameters; A processing system is used to receive the measured parameters and determine the fault location point of the contact network based on the measured parameters.

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