A fault location method and system for FA under a multi-energy scenario based on FTU communication

Abstract

The application discloses a kind of multi-function scene under the method and system for fault locating of FTU communication-based FA, method includes: in backbone line FTU section distance and unit line impedance data;Determine whether the fault occurs in feeder, determine fault loop and according to the direction of fault power determine each FTU is located upstream or downstream of fault;Determine whether line circuit breaker is tripped, and determine the fault loop voltage change and current change measured at each FTU at tripping instant;Get the equivalent impedance of the downstream line associated with each FTU downstream of the fault, and send to adjacent upstream backbone line FTU, determine fault locating point;Get the fault distance when each sub-section in adjacent downstream section respectively occurs fault;Determine the corresponding fault distance as the correct fault distance.The application formula is relatively simple, which is conducive to completing the ranging work locally in FTU, effectively solves the fault locating problem of FA in the scene of feeder along the line distribution load branch and DG branch.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution network fault location, and in particular to a FA fault ranging method and system based on FTU communication in a multi-energy scenario. BACKGROUND

[0002] Power distribution network fault location can be divided into fault section location and fault ranging. The latter should be able to accurately find the specific location of the fault point in the section, so as to reduce the line patrol intensity of field operation and maintenance personnel, timely repair of fault lines, improve the power supply reliability of the power distribution network, and ensure the safe and stable operation of the power system. Fault section location can be completed by feeder automation (FA). At present, FA does not include fault ranging function. FTU (Feeder Terminal Unit) has the functions of real-time data acquisition and processing and communication, and has the condition of further expanding the fault ranging function. For example, FTU expands the ranging function. When the FA fault section location is performed, the field personnel can read the ranging data of the adjacent upstream FTU in the section to find the specific location of the fault point.

[0003] At present, the methods for short-circuit fault ranging of the power distribution network mainly include traveling wave method, impedance method and artificial intelligence method. The traveling wave method needs to install traveling wave acquisition devices at multiple positions in the power distribution network, whether it is single-ended traveling wave or double-ended traveling wave positioning. On the other hand, when the power distribution network has DG (Distributed Generation) access containing power electronic equipment, the equipment will generate a large amount of high-order harmonics. At this time, the reliability and sensitivity based on the traveling wave method will be affected to a certain extent. The impedance method calculates the fault line impedance by using the line parameters and the measured values of the node voltage and current at the fault time, so as to estimate the position between the fault point and the measured node. The impedance method based on the measured data of the existing measuring equipment further brings the problem of complex calculation when considering the influence of load branch and DG access branch. The large amount of data samples accumulated in the operation of the power distribution network can be used for the ranging method of artificial intelligence, but this method needs more measuring equipment, strictly synchronized information and complex calculation. In summary, there is no simple and effective fault ranging method suitable for the existing FTU condition in a multi-energy scenario at present. SUMMARY

[0004] This part aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part and the abstract and title of the specification of the present application to avoid obscuring the purpose of this part, the abstract and the title of the specification. Such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the above existing problems, the present application is proposed. Therefore, the present application provides a FTU communication-based FA fault ranging method in a multi-energy scenario to solve the problem of how to simply and effectively implement FA fault ranging, quickly locate the fault point, eliminate the fault, and reduce the power outage time.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a FTU communication-based FA fault ranging method in a multi-energy scenario, comprising: storing the section distance and unit line impedance data of the adjacent downstream backbone line section and each small section in the backbone line section in the backbone line FTU;

[0008] Judging whether the feeder is faulty, if there is a fault, determining the fault loop, and judging the location of each FTU according to the fault power direction;

[0009] Based on the fault, judging the line circuit breaker tripping state, if it has tripped, determining the fault loop voltage change and current change measured at each FTU at the tripping moment;

[0010] According to the fault loop voltage change and current change measured at each FTU, obtaining the equivalent impedance of the downstream line connected to each FTU downstream of the fault, and sending it to the adjacent upstream backbone line FTU to determine the fault ranging point;

[0011] The FTU at the fault ranging point obtains the fault distance when each small section in the adjacent downstream section fails by opening the additional network and according to the stored data and the received equivalent impedance data;

[0012] According to the FTU at the fault ranging point, it is determined whether each fault distance converges in the corresponding small section, if it converges in the corresponding small section, the corresponding fault distance is determined as the correct fault distance.

[0013] As a preferred scheme of the FTU communication-based FA fault ranging method in a multi-energy scenario, wherein: judging the fault comprises:

[0014] If the feeder fails, each FTU judges whether the downstream fails through the current protection, determines the fault loop based on the fault type, and judges whether it is in the fault upstream according to the fault power direction;

[0015] If the fault power direction is positive, i.e. from the bus to the feeder, it is judged that it is in the fault upstream;

[0016] If the fault power direction is negative, i.e. from the feeder to the bus, or the fault current is 0, it is judged that it is in the fault downstream.

[0017] As a preferred scheme of the FA fault ranging method based on FTU communication in the multi-energy scenario, wherein: the determination of whether the line circuit breaker is tripped includes:

[0018] The FTU detects the current change amount, determines whether the line circuit breaker is tripped, and if not, the fault loop voltage change amount and the current change amount are not calculated.

[0019] If the tripping record is recorded, the local voltage change amount and the current change amount of each FTU at the tripping moment after the fault are calculated.

[0020] As a preferred scheme of the FA fault ranging method based on FTU communication in the multi-energy scenario, wherein: the determination of the fault loop voltage change amount and the current change amount measured at the tripping moment of each FTU includes:

[0021] The phase voltage change amount is the difference between the current voltage and the voltage of the two power frequency periods before tripping, and the phase current change amount is the difference between the current current and the current of the two power frequency periods before tripping.

[0022] The phase voltage change amount of the fault loop measured at each FTU is subtracted to obtain the fault loop voltage change amount, and the phase current change amount of the fault loop measured at each FTU is subtracted to obtain the fault loop current change amount.

[0023] As a preferred scheme of the FA fault ranging method based on FTU communication in the multi-energy scenario, wherein: the determination of the fault ranging point includes:

[0024] The fault loop voltage change amount and the current change amount measured at the tripping moment of each FTU located downstream of the fault are divided to obtain the equivalent impedance of the corresponding downstream line associated with each FTU located downstream of the fault.

[0025] The obtained equivalent impedance value and phase are transmitted to the adjacent upstream backbone line FTU through communication, and the location of the FTU located upstream of the fault and receiving the equivalent impedance data is taken as the fault ranging point.

[0026] As a preferred scheme of the FA fault ranging method based on FTU communication in the multi-energy scenario, wherein: the acquisition of the fault distance when each small section in the adjacent downstream section fails includes:

[0027] Based on the open circuit additional network, i.e. single-sided power supply network, the fault ranging iterative formula corresponding to the fault of each small section in the section is generated based on the fault loop voltage and current change amount of the fault ranging point, the equivalent impedance of the FTU downstream of the fault at the tripping moment, and the distance and line parameters of each section.

[0028]

[0029] wherein, n represents the iteration number, l ak(n+1) , R g(n+1) respectively represent the fault distance and transition resistance obtained in the n+1th iteration, y X(n) , y Y(n) respectively represent y X , y Y , x X(n) , x Y(n)

[0030] respectively represent x X , x Y , l' Fak represents the estimated fault distance, R Fg represents the estimated transition resistance, x represents the current ratio of the equivalent impedance between the trunk line sectional switch and the load branch access point to the equivalent impedance from the load branch access point to the fault point, y represents the current ratio of the current flowing through the fault transition resistance to the current flowing through the equivalent impedance between the trunk line sectional switch and the load branch access point, r1 and x1 respectively represent the resistance value and reactance value of the unit line parameter.

[0031] As a preferred scheme of the FA fault distance measurement method based on FTU communication in the multi-energy scenario, wherein: determining whether each fault distance converges in the corresponding small section comprises:

[0032] According to the FTU located at the fault distance measurement point, it is assumed that a fault occurs in each small section, and it is sequentially judged whether the fault point determined by the fault distance is located in the corresponding small section;

[0033] If the fault point is located in the corresponding small section, it is determined that the fault distance converges in the corresponding small section, if the fault point is not located in the corresponding small section, it is determined that the fault distance does not converge in the corresponding small section, and it is confirmed that the fault does not occur in this small section, and the ranging formula of other small sections is replaced to calculate again.

[0034] In a second aspect, the application provides a FA fault distance measurement system based on FTU communication in a multi-energy scenario, comprising,

[0035] A storage module is used to store the section distance and unit line impedance data of the adjacent downstream trunk line section and each small section in the trunk line section in the trunk line FTU;

[0036] A first judgment module is used to judge whether a feeder line has a fault, if there is a fault, a fault loop is determined, and the position of each FTU is determined according to the fault power direction;

[0037] A second judging module is configured to judge the tripping state of the line circuit breaker based on the fault, and determine the fault loop voltage variation and the current variation measured at each FTU at the tripping moment if the line circuit breaker has been tripped.

[0038] A first calculating module is configured to acquire the equivalent impedance of each downstream line associated with each FTU downstream of the fault according to the fault loop voltage variation and the current variation measured at each FTU, and send the equivalent impedance to the FTU of the adjacent upstream main line to determine the fault ranging point.

[0039] A second calculating module is configured to acquire the fault distance when each sub-section in the adjacent downstream section respectively occurs a fault by opening the additional network and according to the stored data and the received equivalent impedance data.

[0040] An output module is configured to determine whether each fault distance converges in the corresponding sub-section according to the FTU at the fault ranging point, and determine the corresponding fault distance as the correct fault distance if the fault distance converges in the corresponding sub-section.

[0041] In a third aspect, the present application provides an electronic device, comprising:

[0042] a memory and a processor;

[0043] The memory is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions, so as to realize the steps of the FTU communication based FA fault ranging method in the multi-energy scenario.

[0044] In a fourth aspect, the present application provides a computer readable storage medium, which stores computer executable instructions, and the computer executable instructions are executed by the processor to realize the steps of the FTU communication based FA fault ranging method in the multi-energy scenario.

[0045] Compared with the prior art, the application has the beneficial effects that: according to the fault loop voltage variation and the current variation measured at each FTU, the equivalent impedance of the downstream line associated with each FTU downstream of the fault is determined, the equivalent impedance of the downstream line associated with each FTU downstream of the fault is sent to the adjacent upstream backbone line FTU, and the fault ranging point is determined, so that at the moment of the outgoing line breaker tripping, the FTU at the head of the load branch calculates the equivalent load branch impedance based on the local voltage and current variation, without equating the branch to a mathematical model related to the actual voltage and frequency, thereby simplifying the calculation; at the moment of the outgoing line breaker tripping, the FTU at the head of the DG branch calculates the equivalent DG branch impedance based on the local voltage and current variation, without equating the branch to a potential source or current source branch, thereby simplifying the calculation; and the equivalent impedance of the load branch and the DG branch is calculated locally at the head of the branch FTU, and then the impedance value and phase are communicated to the adjacent upstream backbone line FTU of the backbone line, and the communication does not need to be strictly synchronized; the open-circuit additional network is a single-sided power supply network, the current relationship between each part of the network is relatively simple, the ranging calculation is facilitated, and based on the fault ranging iteration formula of the single-sided power supply network, each coefficient can be represented by the parallel and series relationship of the network impedance, without complex matrix calculation, the calculation is relatively simple, and the ranging work can be completed locally at the FTU, thereby effectively solving the fault ranging problem of the FA in the scene of the load branch and the DG branch distributed along the feeder. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor. Among them:

[0047] Figure 1 The overall flowchart of the FA fault ranging method based on FTU communication in the multi-energy scene according to an embodiment of the application;

[0048] Figure 2 The small-current grounding system feeder diagram with load branches and DG branches connected to the section of the FA fault ranging method based on FTU communication in the multi-energy scene according to an embodiment of the application;

[0049] Figure 3 The open-circuit additional network diagram of the CB tripping of the FA fault ranging method based on FTU communication in the multi-energy scene according to an embodiment of the application; Figure 2 The open-circuit additional network diagram of the CB tripping of the FA fault ranging method based on FTU communication in the multi-energy scene according to an embodiment of the application; DETAILED DESCRIPTION

[0050] In order to make the above objectives, characteristics and advantages of the present application more obvious and comprehensible, the specific embodiments of the present application are described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the present application.

[0051] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application, however, can be practiced in a variety of ways beyond the specific details set forth herein without departing from the scope of the present application. It can be appreciated by those skilled in the art that the present application can be practiced without such specific details.

[0052] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. The "in one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent of or selected from other embodiments.

[0053] The present application is described in detail with reference to the drawings. In the detailed description of the embodiments of the present application, the sectional view of the device structure is partially enlarged without the general proportion for the convenience of description, and the schematic view is only an example, which should not limit the scope of protection of the present application. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in actual production.

[0054] Meanwhile, in the description of the present application, it should be noted that the terms "upper, lower, inner and outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first, second or third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0055] Unless otherwise specifically defined and limited, the terms "mounting, connecting, connection" in the present application should be understood broadly, for example: it can be fixed connection, detachable connection or integral connection; it can also be mechanical connection, electrical connection or direct connection, it can also be indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0056] Example 1

[0057] Reference Figures 1-3For an embodiment of the present application, a FTU communication-based FA fault location method in a multi-energy scenario is provided, as shown in Figure 1 , comprising:

[0058] S101, storing in the backbone FTU the adjacent downstream backbone section, the section distance of each sub-section in the backbone section, and the unit line impedance data;

[0059] Specifically, as shown in Figure 2 , a schematic diagram of a small-current grounding system feeder with load branches and DG branches connected to the section, wherein CB is the outgoing circuit breaker of the feeder, FS1, FS2, and FS3 are sectional switches of the backbone, each provided with FTU1, FTU2, and FTU3; FS11, FS12, and FS13 are branch line head switches, each provided with FTU11, FTU12, and FTU13; LS is a tie switch, and LD is a load, wherein a is the load branch access point, DG is a distributed power source, b is the distributed power source branch access point, and the distributed power source can be accessed, and k1, k2, and k3 are fault points.

[0060] FTU1 stores the sub-section distance l 1a between FS1 and a, l ab between a and b, l b2 between b and FS2, and the unit line impedance data corresponding to each sub-section, similarly, FTU2 and FTU3 store the corresponding data.

[0061] It should be noted that, Figure 2 , the 10kV small-current grounding system is taken as an example, the DG is a small hydropower, the large power source on the grid side is an ideal power source, the step-down transformer is 50MVA (not shown on the figure), and the equivalent reactance is 0.1pu. The fault section [FS1, FS2] is 120km long (l 1a is 3km long, l ab is 100km long, and l b2 is 17km long), z1=r1+jx1=(0.1253+j0.2885)Ω, simulated by a π-type line, z1 represents the unit line impedance, r1 and x1 represent the resistance value and reactance value of the unit line parameter respectively; the DG11 capacity is 2MVA; LD11, LD12, and LD2 are each 0.5MW+j0.1mVAR.

[0062] S102, judging whether a fault occurs on the feeder, if a fault exists, determining the fault loop, and judging the position of each FTU according to the fault power direction;

[0063] Specifically, the data measured by the sampling is applied to start the algorithm to determine whether a fault occurs in step S102, and when it is determined that a fault occurs, a related algorithm is applied to determine the fault type and determine the fault loop. For example, if the fault type is an AB phase-to-phase short circuit, the fault loop is the A and B phases; if the fault type is an AC phase-to-phase short circuit, the fault loop is the A and C phases; if the fault type is a BC phase-to-phase short circuit, the fault loop is the B and C phases; and if it is an ABC three-phase short circuit, there are three fault loops of AB, BC and CA.

[0064] Further, if a feeder fails, each FTU determines whether a fault occurs downstream through current protection, determines a fault loop based on a fault type determination, and determines whether it is upstream of the fault according to a fault power direction;

[0065] If the fault power direction is positive, i.e., from the bus to the feeder, it is determined that it is upstream of the fault;

[0066] If the fault power direction is negative, i.e., from the feeder to the bus, or the fault current is 0, it is determined that it is downstream of the fault.

[0067] In the embodiment, the FTU upstream of the fault is referred to as FTUshang, and the FTU downstream of the fault is referred to as FTUxia. Figure 2 When the feeder fails at the k2 fault point, FTU1 determines that a fault occurs based on current protection, determines a fault loop based on a fault type determination, and determines that it is upstream of the fault according to a fault power direction, which is referred to as FTUshang. FTU11, FTU12, FTU2, FTU3 and FTU31 determine that a fault occurs and determine a fault loop, and determine that they are all downstream of the fault according to a fault power direction, which are referred to as FTUxia.

[0068] S103, based on the fault, determining the tripping state of the line circuit breaker, if it has tripped, determining the fault loop voltage variation and current variation measured at each FTU at the tripping moment;

[0069] Further, the FTU detects the current variation to determine whether the line circuit breaker has tripped, if not, there is no fault loop voltage variation and current variation;

[0070] If the tripping record of the line circuit breaker at the fault moment is recorded, the local voltage variation and current variation of each phase of each FTU at the tripping moment are calculated, so as to obtain the fault loop voltage variation and current variation measured at each FTU.

[0071] Further, in an embodiment of the application, determining the fault loop voltage variation and current variation measured at each FTU at the tripping moment comprises:

[0072] The voltage change of each phase is the difference between the voltage before the circuit breaker trips and the voltage of the two power frequency cycles before the circuit breaker trips; the current change of each phase is the difference between the current before the circuit breaker trips and the current of the two power frequency cycles before the circuit breaker trips.

[0073] The voltage change of each phase of the fault loop is obtained by subtracting the voltage changes of each phase of the fault loop measured at each FTU, and the current change of each phase of the fault loop is obtained by subtracting the current changes of each phase of the fault loop measured at each FTU.

[0074] Specifically, assuming that k2 is a phase-to-phase short circuit between phases B and C, the voltage change Δu at phase B at FTU1 is... 1B It is determined by the current voltage u 1B (n F Subtract the voltage u of the two power frequency cycles before the circuit breaker trips. 1B (n F -2N), to obtain the voltage change Δu at the moment of B-phase tripping at FTU1. 1B =u 1B (n F )-u 1B (n F -2N), similar to the voltage change Δu at the instantaneous tripping of phase C at FTU1. 1C The change in phase B current at FTU1 is the current i 1B (n F Subtract the current i from the two power frequency cycles before the circuit breaker trips. 1B (n F -2N), to obtain the instantaneous current change Δi at the B-phase tripping moment of FTU1. 1B =i 1B (n F )-i 1B (n F -2N), similar to the instantaneous current change Δi at the C-phase tripping point of FTU1. 1C Where N is the number of sampling points in a power frequency cycle, n F The nth time after the circuit breaker is tripped F One sampling point.

[0075] The fault loop consists of phases B and C. The voltage and current changes in the fault loop measured at FTU1 are Δu and Δu, respectively. 1Fm =Δu 1FmBC =Δu 1B -Δu 1C , Δi 1Fm =Δi 1FmBC =Δi 1B -Δi 1C The power frequency variation component is obtained by Fourier transform and represented by phasors.

[0076] Figure 2 The FTU11 obtains the fault loop voltage and current variation at the moment of switching off as The FTU12 obtains the fault loop voltage and current variation at the moment of switching off as The FTU2 obtains the fault loop voltage and current variation at the moment of switching off as The FTU3 obtains the fault loop voltage and current variation at the moment of switching off as The FTU31 obtains the fault loop voltage and current variation at the moment of switching off as

[0077] In S104, the equivalent impedance of the downstream line associated with each FTU downstream of the fault is obtained according to the measured fault loop voltage and current variation at each FTU, and is sent to the adjacent upstream backbone line FTU to determine the fault ranging point.

[0078] It should be noted that the time for obtaining the variation is very short, and during this time, the downstream line of the FTUxia can be represented by a constant impedance, wherein the downstream line of the FTUxia can be a load branch, a DG branch (including a parallel branch of the DG and the load) or a downstream line associated with the FTUxia.

[0079] The determination of the fault ranging point includes:

[0080] The fault loop voltage and current variation measured at the moment of switching off at each FTU downstream of the fault are divided to obtain the equivalent impedance of the downstream line associated with each FTU downstream of the fault.

[0081] The obtained equivalent impedance value and phase are transmitted to the adjacent upstream backbone line FTU through communication, and only the FTUshang adjacent to the fault section upstream of the fault receives the impedance information. According to the position of the FTU located upstream of the fault and receiving the equivalent impedance data, the FTU is taken as the fault ranging point, and the FTU is called FTUceju.

[0082] Specifically, Figure 2 The equivalent impedance of the DG branch where the FS11 is located can be represented by Z 11.eq , the equivalent impedance of the load branch at the FS12 can be represented by Z 12.eq , the equivalent impedance of the downstream part of the FS2 can be represented by Z 2.eq , the equivalent impedance of the downstream part of the FS3 can be represented by Z 3.eq , the equivalent impedance of the load branch at the FS31 can be represented by Z 31.eq , and the specific formula is as follows:

[0083]

[0084] Among them, FTU11, FTU12, and FTU2 will respectively Z 11.eq Z 12.eq Z 2.eq The communication is sent to FTU1, which is FTUshang. If it also receives impedance data, it becomes FTUceju. FTU3 will then transmit Z... 3.eq Communication is sent to FTU2, but FTU2 is FTUxia, so it is not FTUceju. FTU1 is FTUshang, so there is no need to transmit upstream. If there is another FTUshang upstream of FTU1, the latter will not receive impedance data, so it can be determined that it is not FTUceju. Therefore, only the FTUshang adjacent to the fault point on the feeder is FTUceju.

[0085] S105, the FTU located at the fault location point, obtains the fault distance when each small cell in the adjacent downstream segment experiences a fault through an open-circuit supplementary network and based on stored data and received equivalent impedance data.

[0086] In this embodiment, the open-circuit supplementary network is a single-sided power supply network. The voltage and current change data of the fault loop at FTUceju have been obtained. The constant impedance of the downstream part of FTUxia adjacent to FTUceju at the moment of tripping has been communicated to FTUceju. Furthermore, the distances and line parameters of this section are also known. Based on the open-circuit supplementary network, the ranging iteration formula corresponding to each small segment of this section when it is faulty can be generated.

[0087] Specifically, Figure 2 When a phase-to-phase short-circuit fault occurs at point k2, the open-circuit auxiliary network after the CB trips is as follows: Figure 3 As shown, since the current after the circuit breaker is used is a sampled value of two power frequency cycles, the sampling moment after the circuit breaker is very short, and there is no need to consider the changes in the large power grid side and the equivalent potential source of DG and their respective internal impedances and loads at the moment of circuit breaker opening.

[0088] Figure 3 In the middle, Z S It is the equivalent impedance on the power grid side of the busbar, Z S1 Z is the equivalent impedance between the busbar and FS1. 1a It is the equivalent impedance (Z) between FS1 and point a. 1a =l 1a z1), Z ak It is the equivalent impedance between a and k2, where Z ak =l ak z1,l ak Z is the distance between a and k2.kb is the equivalent impedance between k2 and b, Z b2 is the equivalent impedance between b and FS2, R g is the fault transition resistance.

[0089] current source is the fault loop current frequency variation at the point of the circuit breaker CB at the moment of opening, the open additional network is a single-sided power supply network, the fault loop voltage variation at each point of FS11, FS12, FS2 (not shown in the figure), are the fault loop current frequency variations at the moment of opening through Z 1a , Z ak , and R g respectively.

[0090] According to the above data information, the distance measurement formula is expressed as:

[0091]

[0092] wherein, l' Fak represents the estimated fault distance, R' Fg represents the estimated transition resistance, x represents Figure 3 the ratio of the current flowing through Z ak to the current flowing through Z 1a , and y represents the ratio of the current flowing through R g to the current flowing through Z 1a ; The relationship between x and y currents is expressed as the relationship between impedances, which is expressed as:

[0093]

[0094]

[0095] Further decompose x and y into virtual and real impedance expressions, which are expressed as:

[0096] x = x X +jx Y , y = y X +jy Y

[0097] wherein, x X and x Y represent the real and imaginary parts of x respectively, y X and y Y represent the real and imaginary parts of y respectively, x​​​​X x Y y X y Y Both are consistent with the actual l ak and R g Related;

[0098] in,

[0099]

[0100]

[0101] Among them, Z bG.eq express Figure 3 The branch impedance Z at point b 12.eq The sum of the two series impedances of the other branch (Z) b2 +Z 2.eq The parallel impedance of ).

[0102] The imaginary and real solutions of the distance measurement formula are transformed and expressed as follows:

[0103]

[0104] The iterative equation derived from the above transformation is expressed as:

[0105]

[0106] Where n represents the number of iterations, l ak(n+1) R g(n+1) Let y represent the fault distance and transition resistance obtained in the (n+1)th iteration, respectively. X(n) y Y(n) Let y be the result of the nth iteration. X y Y x X(n) x Y(n) Let x represent the result of the nth iteration. X x Y .

[0107] Similarly, it can be concluded that... Figure 2 The iterative ranging formulas at FTU1 when k1 and k3 are faults are given.

[0108] S106. Based on the FTU located at the fault location point, determine whether each fault distance converges within the corresponding cell segment. If it converges within the corresponding cell segment, then determine the corresponding fault distance as the correct fault distance.

[0109] Specifically, according to the FTU located at the fault ranging point, the corresponding fault distance is calculated according to the iterative ranging formula of each subsection, it is judged whether the fault distance converges in the corresponding subsection, if the fault distance converges in the corresponding subsection, the corresponding fault distance is determined as the correct fault distance, if the fault distance does not converge in the corresponding subsection, it is determined that the fault does not occur in the subsection, then the ranging formula of other subsection is replaced to calculate.

[0110] Further, according to the FTU located at the fault ranging point, it is assumed that the fault occurs in each subsection, and it is judged whether the fault point determined by the fault distance is located in the corresponding subsection;

[0111] If the fault point is located in the corresponding subsection, it is determined that the fault distance converges in the corresponding subsection, if the fault point is not located in the corresponding subsection, it is determined that the fault distance does not converge in the corresponding subsection.

[0112] Specifically, Figure 2 When k2 fault occurs, FTU1 first assumes that k3 fault occurs, the result obtained after convergence by using the corresponding iterative calculation formula will not be between b and FS2, then FTU1 assumes that k2 fault occurs, the result obtained after convergence by using the corresponding iterative calculation formula will be between a and b, and the result is the correct fault distance.

[0113] It should be noted that the FA of the present application can combine fault section judgment and take advantage of the FTU multi-point arrangement and the communication between FTUs to further perform fault ranging on the FTU of the adjacent upstream backbone line in the fault section. The existing distribution line ranging method considering load branches and DG access requires higher requirements for the arrangement of measuring points and is more complex in calculation, which is not conducive to realizing fault ranging locally at the FTU under the existing equipment conditions. The present application proposes to obtain the fault loop voltage and current variation measured by each FTU at the instant of opening of the outgoing circuit breaker, to equivalently model the downstream phase connection part of FTUxia as a constant impedance model, and to calculate the fault distance by using the iterative ranging formula of each subsection. The calculation formula is relatively simple, which is conducive to completing the ranging work locally at the FTU. The method effectively solves the fault ranging problem of the FA in the scene of load branches and DG branches distributed along the feeder, and can be used as an extended function of the FA.

[0114] The above is a schematic scheme of the FA fault ranging method based on FTU communication in the multi-energy scene of the present embodiment. It should be noted that the technical scheme of the FA fault ranging system based on FTU communication in the multi-energy scene belongs to the same concept as the technical scheme of the FA fault ranging method based on FTU communication in the multi-energy scene described above. The technical scheme of the FA fault ranging system based on FTU communication in the multi-energy scene of the present embodiment is not described in detail, and can be referred to the description of the technical scheme of the FA fault ranging method based on FTU communication in the multi-energy scene.

[0115] The FTU communication-based FA fault location system in the multi-energy scenario in the embodiment comprises:

[0116] A storage module is configured to store the section distance and unit line impedance data of the adjacent downstream backbone line section and each small section in the backbone line section of the backbone line FTU.

[0117] A first judgment module is configured to determine whether a fault occurs in the feeder, and if a fault exists, determine the fault loop and determine the location of the fault of each FTU according to the fault power direction.

[0118] A second judgment module is configured to determine the line breaker tripping state based on the fault, and if the breaker has tripped, determine the fault loop voltage variation and current variation measured at each FTU at the tripping moment.

[0119] A first calculation module is configured to obtain the equivalent impedance of the downstream line associated with each FTU downstream of the fault according to the fault loop voltage variation and current variation measured at each FTU, and send the equivalent impedance to the adjacent upstream backbone line FTU to determine the fault location point.

[0120] A second calculation module is configured to obtain the fault distance when each small section in the adjacent downstream section fails by opening the additional network and according to the stored data and the received equivalent impedance data.

[0121] An output module is configured to determine whether each fault distance converges in the corresponding small section according to the FTU at the fault location point, and if it converges in the corresponding small section, determine the corresponding fault distance as the correct fault distance.

[0122] The embodiment also provides an electronic device suitable for the FTU communication-based FA fault location in the multi-energy scenario, comprising:

[0123] A memory and a processor, the memory is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions to implement the multi-energy scenario-based FTU communication-based FA fault location method proposed in the above embodiment.

[0124] The embodiment also provides a storage medium having a computer program stored thereon, the program being executed by a processor to implement the multi-energy scenario-based FTU communication-based FA fault location method proposed in the above embodiment.

[0125] The storage medium proposed in this embodiment and the FA fault ranging method based on FTU communication in a multi-energy scenario proposed in the above embodiment belong to the same inventive concept, and the technical details not described in detail in this embodiment can be seen from the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0126] Through the above description of the embodiments, those skilled in the art can clearly understand that the present application can be realized by software and necessary general hardware, and of course can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a floppy disk, a read-only memory (ROM), a random access memory (RAM), a FLASH, a hard disk or an optical disk, etc., including a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the method of each embodiment of the present application.

[0127] Embodiment 2

[0128] Referring to Table 1, for an embodiment of the present application, a FA fault ranging method based on FTU communication in a multi-energy scenario is provided, in order to verify its beneficial effects, economic benefit calculation and simulation experiment are carried out for scientific demonstration.

[0129] In this embodiment, the operation and maintenance personnel can determine the FTUceju position based on the FA and read the ranging data of the FTU, realize the FA fault ranging, and Table 1 is the iteration calculation result when the fault distance is changed, wherein the fault transition resistance R g = 5Ω, the unit of distance is km, and the unit of resistance is Ω.

[0130] Wherein, l ak.z , R g.z is the result of iteration calculation, respectively called quasi-fault distance and quasi-transition resistance, and the error is represented as:

[0131]

[0132] The simulation step is 50μs, and the iteration convergence conditions of fault distance and transition resistance are respectively:

[0133] |l ak(n+1) -l ak(n) |<ε l

[0134] |R g(n+1) -R g(n) |<εR

[0135] wherein, l ak(n) , R g(n) respectively represent the fault distance and transition resistance obtained by the nth iteration, ε l , ε R respectively represent a small positive number given in advance for judging whether the iteration calculation of the fault distance and the iteration calculation of the transition resistance converge, and ε l = 0.01 km and ε R = 0.01 Ω.

[0136] Table 1: Iteration calculation result of changing fault distance

[0137] l ak ]]> l ak.z ]]> [R g.z ]]> Δl ak %]] 90 91.5 4.5 1.67 50 50.8 4.65 1.6 10 10.39 4.88 3.9

[0138] As can be seen from Table 1, the fault distance measurement method of the present application is convenient, fast and more accurate for the feeder with load and DG connected along the line, and the method has more advantages in long fault distance measurement. In addition, based on the fault section positioning function of the FA, the operator can know that the section between FS1 and FS2 is the fault section, and FTU1 is FTUceju, so the measurement result can be directly read at FTU1, thereby facilitating fast troubleshooting and reducing power outage time. Figure 2

[0139] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and all should be covered in the scope of the claims of the present application.​

Claims

1. A fault location method for FA under multi-energy scenarios based on FTU communication, characterized in that, The method comprises the following steps: Storing the distance between the FTU and the next downstream FTU, the distance between each section in the trunk line section and the unit line impedance data in the FTU; Determining whether the feeder is faulty, and if so, determining the fault loop and the location of each FTU based on the fault power direction; Based on the fault, determining the open state of the circuit breaker, and if so, determining the fault loop voltage and current variation measured by each FTU at the moment of opening; Based on the fault loop voltage and current variation measured by each FTU, obtaining the equivalent impedance of the downstream line associated with each FTU downstream of the fault, and sending it to the next upstream FTU to determine the fault ranging point; The FTU at the fault ranging point obtains the fault distance of each section in the next downstream section by opening the additional network and based on the stored data and the received equivalent impedance data; Based on the FTU at the fault ranging point, determining whether each fault distance converges in the corresponding section, and if so, determining the corresponding fault distance as the correct fault distance; Obtaining the fault distance of each section in the next downstream section when a fault occurs in each section includes: Based on the fault loop voltage and current variation at the fault ranging point, the equivalent impedance of the FTU downstream of the fault at the moment of opening, and the distance and line parameters of the section, the corresponding ranging iteration formula of each section fault in the section is generated based on the open additional network, i.e. single-sided power network, which is represented as: wherein n represents the iteration number, l ak(n+1) , R g(n+1) respectively represent the fault distance and transition resistance obtained in the n+1th iteration, y X(n) , y Y(n) respectively represent y X , y Y obtained in the nth iteration, x X(n) , x Y(n) respectively represent x X , x Y obtained in the nth iteration, l' Fak represents the estimated fault distance, R' Fg represents the estimated transition resistance, x represents the current ratio of the equivalent impedance between the trunk line sectionalizer and the load branch access point to the equivalent impedance of the load branch access point to the fault point, y represents the current ratio of the current flowing through the fault transition resistance to the current flowing through the equivalent impedance between the trunk line sectionalizer and the load branch access point, r1 and x1 respectively represent the resistance value and the reactance value of the unit line parameter.

2. The FTU communication based FA fault location method under multi-energy scenario of claim 1, wherein, The determination of the fault includes: If the feeder is faulty, each FTU determines whether the downstream is faulty based on the current protection, determines the fault loop based on the fault type, and determines whether it is upstream of the fault based on the fault power direction; If the fault power direction is positive, it is determined that it is upstream of the fault; If the fault power direction is negative or the fault current is 0, it is determined that it is downstream of the fault.

3. The FTU communication based FA fault location method under multi-energy scenarios according to claim 1 or 2, characterized in that, The determination of whether the line circuit breaker is open includes: Detecting the current variation by the FTU to determine whether the line circuit breaker is open, and if not, there is no fault loop voltage and current variation; If the opening record of the line circuit breaker is recorded at the moment of opening after the fault, the local voltage and current variation of each phase of each FTU at the moment of opening are calculated respectively.

4. The FTU communication based FA fault location method under multi-energy scenario of claim 3, wherein, The determination of the fault loop voltage and current variation measured by each FTU at the moment of opening includes: The voltage variation of each phase is the difference between the current voltage and the voltage of the two power frequency cycles before opening, and the current variation of each phase is the difference between the current and the current of the two power frequency cycles before opening; The voltage variation of each phase of the fault loop measured by each FTU is subtracted to obtain the fault loop voltage variation, and the current variation of each phase of the fault loop measured by each FTU is subtracted to obtain the fault loop current variation.

5. The FTU communication based FA fault location method under multi-energy scenario of claim 4, wherein, The determination of the fault ranging point includes: Dividing the fault loop voltage and current variation measured by each FTU downstream of the fault at the moment of opening to obtain the equivalent impedance of the downstream line associated with each FTU downstream of the fault; The obtained equivalent impedance value and phase are transmitted to an adjacent upstream backbone line FTU through communication, and the FTU located at the fault upstream and receiving the equivalent impedance data is taken as a fault ranging point.

6. The FTU communication based FA fault location method under multi-energy scenario of claim 1, wherein, The determination of whether the fault distance converges in the corresponding section includes: According to the FTU located at the fault ranging point, assuming that a fault occurs in each section, and judging in turn whether the fault point determined by the fault distance is located in the corresponding section; If the fault point is located in the corresponding section, it is determined that the fault distance converges in the corresponding section, if the fault point is not located in the corresponding section, it is determined that the fault distance does not converge in the corresponding section, and it is confirmed that the fault does not occur in this section, and the ranging formula of other sections is replaced for calculation again.

7. A FTU communication based FA fault location system under multi-energy scenario, characterized in that, It includes, A storage module is configured to store the section distance and unit line impedance data of the adjacent downstream backbone line section and each section in the backbone line section in the backbone line FTU; A first judgment module is configured to judge whether a feeder line is faulty, and if there is a fault, determine a fault loop, and determine the position of each FTU according to the fault power direction; A second judgment module is configured to judge the line circuit breaker opening state based on the fault, and if it has been opened, determine the fault loop voltage change and current change measured at each FTU at the opening moment; A first calculation module is configured to obtain the equivalent impedance of the downstream line associated with each FTU downstream of the fault according to the fault loop voltage change and current change measured at each FTU, and send it to the adjacent upstream backbone line FTU to determine the fault ranging point; A second calculation module is configured to obtain the fault distance when each section in the adjacent downstream section respectively occurs a fault by the FTU located at the fault ranging point through the open additional network and according to the stored data and the received equivalent impedance data; An output module is configured to determine whether the fault distance converges in the corresponding section according to the FTU located at the fault ranging point, and if it converges in the corresponding section, determine the corresponding fault distance as the correct fault distance. The obtaining of the fault distance when each section in the adjacent downstream section respectively occurs a fault includes: According to the fault loop voltage and current change of the fault ranging point, the equivalent impedance of the FTU adjacent to the fault downstream at the opening moment, and the distance and line parameters of the section, the ranging iterative formula corresponding to each section fault of the section is generated based on the open additional network, i.e. single-sided power network, which is expressed as: wherein n represents the iteration number, l ak(n+1) , R g(n+1) respectively represent the fault distance and transition resistance obtained in the n+1th iteration, y X(n) , y Y(n) respectively represent y X , y Y obtained in the nth iteration, x X(n) , x Y(n) respectively represent x X , x Y obtained in the nth iteration, l' Fak represents the estimated fault distance, R' Fg represents the estimated transition resistance, x represents the current ratio of the equivalent impedance between the trunk line sectionalizing switch and the load branch access point to the equivalent impedance from the load branch access point to the fault point, y represents the current ratio of the current flowing through the fault transition resistance to the current flowing through the equivalent impedance between the trunk line sectionalizing switch and the load branch access point, r1 and x1 respectively represent the resistance value and the reactance value of the unit line parameter. 8.An electronic device comprising: a memory and a processor; the memory is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions, and the computer executable instructions, when executed by the processor, implement the steps of the FTU communication based FA fault ranging method in the multi-energy scenario according to any one of claims 1 to 6. 9.A computer readable storage medium storing computer executable instructions, the computer executable instructions, when executed by a processor, implement the steps of the FTU communication based FA fault ranging method in the multi-energy scenario according to any one of claims 1 to 6.

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