WO2017134136A1 - Method of locating a fault in a power transmission scheme - Google Patents

Method of locating a fault in a power transmission scheme Download PDF

Info

Publication number
WO2017134136A1
WO2017134136A1 PCT/EP2017/052205 EP2017052205W WO2017134136A1 WO 2017134136 A1 WO2017134136 A1 WO 2017134136A1 EP 2017052205 W EP2017052205 W EP 2017052205W WO 2017134136 A1 WO2017134136 A1 WO 2017134136A1
Authority
WO
WIPO (PCT)
Prior art keywords
voltage
power transmission
phasors
connection point
phasor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2017/052205
Other languages
French (fr)
Inventor
Hengxu Ha
Sankara Subramanian
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GE Vernova GmbH
Original Assignee
General Electric Technology GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Technology GmbH filed Critical General Electric Technology GmbH
Priority to CN201780009737.1A priority Critical patent/CN108603910B/en
Priority to JP2018539944A priority patent/JP2019503642A/en
Priority to BR112018015516A priority patent/BR112018015516A2/en
Priority to CA3012751A priority patent/CA3012751A1/en
Priority to US16/074,797 priority patent/US10830807B2/en
Priority to MX2018009359A priority patent/MX382920B/en
Publication of WO2017134136A1 publication Critical patent/WO2017134136A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H02H7/263—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of measured values
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

Definitions

  • This invention relates to a method of locating a fault in a power transmission scheme, an apparatus for locating a fault in a power transmission scheme, and a power transmission scheme comprising such an apparatus.
  • a method of locating a fault in a power transmission scheme including a plurality of power transmission sections and a plurality of connection points, the plurality of connection points including a first end connection point, a second end connection point and at least one intermediate connection point connected between the first and second end connection points, each of the plurality of power transmission sections arranged to interconnect a respective two of the plurality of connection points such that the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate connection point interconnects a or a respective neighbouring pair of the power transmission sections, the method comprising the steps of:
  • the method of the invention not only results in efficient determination of the location of a fault in a power transmission scheme, but also is accurate due to the consideration of the distributed parameters of the power transmission scheme.
  • the method of the invention is readily scalable to accommodate different topologies of the power transmission scheme. The latter is particularly advantageous for use in a power transmission scheme with a complex layout, such as a multi-ended power transmission scheme.
  • the method of the invention therefore permits quick determination of the location of a fault in a power transmission scheme, which reduces the time required to locate and repair the fault and thereby minimises the downtime of the power transmission scheme.
  • the first and second sets of voltage phasors may be determined in various ways.
  • the method may further include the steps of: measuring first and second end current phasors at the first and second end connection points respectively;
  • the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points that are determined based on the measured first end voltage and current phasors;
  • the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage and current phasors.
  • the power transmission section connected to the first connection point may be designated as a first power transmission section
  • the power transmission section connected to the second connection point may be designated as a second power transmission section
  • the or each other power transmission section connected between the or the respective neighbouring pair of intermediate connection points may be designated as an intermediate power transmission section.
  • the method may further include the steps of:
  • the first set of current phasors includes respective current phasors in the first, second and intermediate power transmission sections that are determined based on the measured first end voltage and current phasors;
  • the second set of current phasors includes respective current phasors in the first, second and intermediate power transmission sections that are determined based on the measured second end voltage and current phasors.
  • the first and second sets of current phasors may be used in the method of the invention to help identify the location of the fault, e.g. by calculating fault distance.
  • the respective voltage phasors at the second and intermediate connection points of the first set of voltage phasors may be determined based on the measured first end voltage phasor and the first set of current phasors
  • the respective voltage phasors at the first and intermediate connection points of the second set of voltage phasors may be determined based on the measured second end voltage phasor and the second set of current phasors.
  • the power transmission scheme may be a multi-ended power transmission scheme.
  • the power transmission scheme may further include a further power transmission section connecting the intermediate connection point to a further connection point or a plurality of further power transmission sections each connecting a respective one of the intermediate connection points to a respective one of a plurality of further connection points.
  • the method may further include the steps of:
  • the or each further current phasor may be used in the method of the invention to help identify the location of the fault, e.g. by calculating the voltage and current phasors of a neighbouring connection point.
  • the respective current phasors in the first, second and intermediate power transmission sections of the first set of current phasors may be determined based on the measured first end voltage and current phasors and the or each further current phasor, and the respective current phasors in the first, second and intermediate power transmission sections of the second set of current phasors may be determined based on the measured second end voltage and current phasors and the or each further current phasor.
  • the method may further include the steps of:
  • the or each further voltage phasor may be used in the method of the invention to help identify the location of the fault, as detailed later.
  • the steps of the method of the invention may include further sub-steps in order to better pinpoint the location of the fault in the power transmission scheme.
  • the step of comparing the first and second sets of voltage phasors may include:
  • the step of comparing the first and second sets of voltage phasors may include:
  • the step of comparing the first and second sets of voltage phasors further includes:
  • the step of comparing the first and second sets of voltage phasors further includes: if the minimum amplitude value is more than the predefined criterion threshold, comparing the phase or amplitude of the subtraction voltage phasor of the connection point corresponding to the minimum amplitude value with the phase or amplitude of the subtraction voltage phasor of a neighbouring connection point to identify the power transmission section corresponding to the location of the fault.
  • the method may further include the step of using the corresponding voltages and currents to form a two-ended system equivalent of the power transmission section identified as the location of the fault.
  • the method may further include the step of determining the distance of the fault along the power transmission section on the basis of the voltage and currents of the two-ended system equivalent.
  • an apparatus for locating a fault in a power transmission scheme including a plurality of power transmission sections and a plurality of connection points, the plurality of connection points including a first end connection point, a second end connection point and at least one intermediate connection point connected between the first and second end connection points, each of the plurality of power transmission sections arranged to interconnect a respective two of the plurality of connection points such that the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate connection point interconnects a or a respective neighbouring pair of the power transmission sections, the apparatus configured to:
  • a power transmission scheme including a plurality of power transmission sections and a plurality of connection points, the plurality of connection points including a first end connection point, a second end connection point and at least one intermediate connection point connected between the first and second end connection points, each of the plurality of power transmission sections arranged to interconnect a respective two of the plurality of connection points such that the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate connection point interconnects a or a respective neighbouring pair of the power transmission sections, wherein the power transmission scheme further includes the apparatus of the second aspect of the invention.
  • Figure 1 shows a schematic representation of the topology of a power transmission scheme according to an embodiment of the invention
  • Figure 2 shows a schematic representation of an apparatus forming a part of the power transmission scheme of Figure 1;
  • Figure 3 illustrates a voltage profile along the power transmission scheme of Figure 1 during the occurrence of a fault
  • Figure 4 shows a flow diagram which illustrates steps in a method of locating a fault in the power transmission scheme of Figure 1.
  • a fault may occur during the operation of a power transmission scheme, thus potentially resulting in downtime in order to ensure the safety of the power transmission scheme and its users.
  • Such downtime however prevents electricity from being supplied via the power transmission scheme. This not only inconveniences end consumers reliant on the electricity transmitted via the power transmission scheme but also results in economic damages to the operator of the power transmission scheme.
  • a power transmission scheme according to an embodiment of the invention is shown in Figure 1.
  • the power transmission scheme comprises a plurality of power transmission sections and a plurality of connection points. Each connection point is in the form of a junction.
  • the plurality of junctions includes a first end junction, a second end junction and a plurality of intermediate junctions connected between the first and second end junctions.
  • the first end junction is indicated as J 0
  • the second end junction is indicated as J 5
  • the intermediate junctions are respectively indicated as J 1 , J 2 , J 3 and J 4 .
  • a first of the power transmission sections is connected between junctions J 0 and J 1 .
  • a second of the power transmission sections is connected between junctions J 4 and J 5 .
  • the three remaining power transmission sections are intermediate power transmission sections connected between junctions J 1 and J 2 , between junctions J 2 and J 3 and between junctions J 3 and J 4 respectively.
  • each of the plurality of power transmission sections is arranged to interconnect a respective two of the plurality of junctions J 0 ,J 1 ,J 2 ,J 3 ,J4,J5 such that the plurality of power transmission sections are connected successively between the first and second end junctions J 0 ,J 5 and such that each intermediate junction J 1 ,J 2 ,J 3 ,J4 interconnects a respective neighbouring pair of the power transmission sections.
  • junction J 0 is directly connected to a first terminal Tl .
  • junction J 5 is directly connected to a second terminal T6.
  • the power transmission scheme further includes a plurality of further power transmission sections.
  • the junction J 1 is connected to a third terminal T2 via a first, further power transmission section
  • the junction J 2 is connected to a third terminal T3 via a second, further power transmission section
  • the junction J 3 is connected to a third terminal T4 via a third, further power transmission section
  • the junction J 4 is connected to a third terminal T5 via a fourth, further power transmission section.
  • the power transmission scheme further includes an apparatus that comprises a plurality of blocks A, B, C and D, as shown in Figure 2.
  • An apparatus that comprises a plurality of blocks A, B, C and D, as shown in Figure 2.
  • the method of the invention is based on the measurement of the voltage phasors at the junctions J 0 and J 5 , the calculation of the voltage phasors in the rest of the power transmission scheme based on the measured voltage phasors, and the comparison of the voltage phasors. For example, if the fault is located between junctions J 2 and J 3 , the voltage at the point of fault calculated based on the voltage phasor at the junction J 0 is the same as the voltage at the point of fault calculated based on the voltage phasor at the junction J 5 .
  • Figure 3 illustrates the voltage profile along the power transmission scheme of Figure 1 during the occurrence of a fault.
  • the method of the invention includes the following steps. Initially voltage phasors are measured at the terminals T1,T2,T3,T4,T5,T6 respectively, and current phasors are measured
  • the measured voltage and current phasors are then fed into Block A of the apparatus to calculate: first and second sets of voltage phasors at the junctions; first and second sets of current phasors in the power transmission sections interconnecting the junctions; and further voltage phasors at the junctions.
  • the following steps are based on J 0 as a starting point and J 5 as an end point. It is envisaged that, in other embodiments of the invention, the following steps are based on J 5 as a starting point and J 0 as an end point. It is also envisaged that, in still other embodiments of the invention, T2 may be used in place of J 0 as a starting point and/or T5 may be used in place of J 5 as an end point.
  • the selection of the starting and end points can be indicated by a topology matrix representing the topology of the power transmission scheme, which is settable and inputted by a user.
  • the topology matrix is defined as follows:
  • the number of rows in the topology matrix equals the number of terminals so that each row of the topology matrix represents each terminal, and the number of columns in the topology matrix equals the number of junctions so that each column of the topology matrix represents each junction.
  • the mth row, nth column of the matrix is set as 1 ; if the mth terminal is not connected with nth junction, then the mth row, nth column of the matrix is set as 0.
  • the voltage phasor at junction the vo ltage phasor at junction the voltage phasor at junction the voltage phasor at junction the voltage phasor at junction and the voltage
  • the current in the power transmission section between junctions In the first set of current phasors the current in the power transmission section between junctions , the current in the power transmission section between junctions the current in the power transmission section between junctions L, the current in the power transmission section between junctions and the current in the power transmission section between junctions
  • the voltage phasor at junction J 0 is equal to the measured voltage phasor V at terminal Tl, and the current I in the power transmission section between junctions
  • J 0 and J 1 is equal to the current phasor ⁇ measured at the terminal Tl .
  • the current phasor of the preceding power transmission section based on the voltage phasor of the preceding junction, the current phasor of the preceding power transmission section, and the current phasor in the further power transmission medium connected to the preceding junction.
  • k ranges from 1 to 5;
  • the k- lth junction to kth the junction is the nth-terminal-to-kth-junction current flowing in the further power transmission medium connected to the kth junction.
  • the voltage phasor at junction the voltage phasor at junction the voltage phasor at junction the voltage phasor at junction the voltage
  • the voltage phasor at junction J 6 is equal to the measured voltage phasor S at terminal T5, and the current in the power transmission section between junctions J 4 and J 5 is equal to the current phasor ⁇ 6 measured at the terminal T6.
  • each of the other current phasors in the respective power transmission sections are based on the voltage phasor of the preceding junction, the current phasor of the preceding power transmission section, and the current phasor in the further power transmission medium connected to the preceding junction.
  • k is the line length of the power transmission section interconnecting the k+ lth junction to the kth junction; is the nth-terminal-to-kth-junction current flowing in the further power transmission medium connected to the kth junction.
  • junction J 1 The further voltage and current phasors for junction J 1 with respect to terminal T2 are calculated by the following equations:
  • interconnecting junction J 1 to terminal T2 is the admittance per length of the further power transmission section
  • interconnecting junction J 1 to terminal T2; is the line length of the further power transmission section interconnecting
  • junction J 4 to terminal T5; is the line length of the further power transmission section interconnecting
  • the first and second sets of voltage phasors VJL,VVR and the further voltage phasors VJT are then fed into Block B to compare the voltage phasors to identify the power transmission section or junction corresponding to the location of the fault, as follows. The following steps are illustrated in the flow diagram of Figure 4.
  • a subtraction voltage phasor for each junction is obtained.
  • the subtraction voltage phasor of each junction is equal to the difference between the corresponding voltage phasors of the first and second sets of voltage phasors VJL,VJR, as shown in the following equation.
  • Vthresl is exemplarily set at 0.02 times ofthe rated voltage ofthe power transmission scheme so that, for example, if the rated voltage is 110 V, then Vthresl is 2.2 V.
  • the minimum amplitude value ⁇ Vmin is less than the predefined voltage threshold Vthresl, it indicates that the fault is either on the junction corresponding to the minimum amplitude value ⁇ Vmin or in the further power transmission section connected to this junction. For example, if it indicates that the fault is either on the junction J 3 or in the further power transmission section interconnecting the junction J 3 and the terminal T 4 .
  • Vthresl is exemplarily set at 0.05 times of the rated voltage of the power transmission scheme so that, for example, if the rated voltage is 110 V, then Vthresl is 5.5 V. If
  • ⁇ Vthres2, then the fault is located on the kth junction. If there are multiple terminals connected to the junction in question, the discriminative criterion is applied to each terminal in turn.
  • the minimum amplitude value ⁇ Vmin is more than the predefined voltage threshold Vthresl, it indicates that the fault is in the power transmission section interconnecting the kth junction and the k+ lth junction. For example, if it indicates that
  • the fault is in the power transmission sections interconnecting the junctions
  • the location of the fault is more accurately determined by comparing the voltage phasor of a given junction with the voltage phasor of a neighbouring junction to identify the power transmission section corresponding to the location of the fault. Different criterion may be applied to determine the power transmission section in which the fault is located.
  • the power transmission section in which the fault is located is determined by comparing the phases of the subtraction voltage phasor of a given junction and the subtraction voltage phasor ⁇ of a neighbouring junction to check whether the comparison meets the followin criterion: If the criterion is met, then the fault is located in the power transmission section interconnecting junctions Jk and Jk+i .
  • the power transmission section in which the fault is located is determined by comparing the amplitudes of the subtraction voltage phasor ⁇ Vjk of a given junction and the subtraction voltage phasor ⁇ Vjk+i of a neighbouring junction to check whether an am litude comparison meets the following criterion:
  • the fault is located in the power transmission section interconnecting junctions Jk and Jk+i .
  • the power transmission section in which the fault is located is determined by comparing the subtraction voltage phasor ⁇ Vjk of a given junction and the subtraction voltage phasor ⁇ Vjk+i of a neighbouring junction to check whether the comparison meets the following criterion.
  • the fault is located in the power transmission section interconnecting junctions Jk and Jk+i .
  • Block C selects the appropriate voltage and current phasors from VJL, VJR, IJL and IJR and forms a two-ended system equivalent of the power transmission section identified as the location of the fault with voltages and currents VM, VN, IM, IN.
  • the relevant power transmission section is connected between junctions Jk and Jk+i , the voltage and current phasors are selected to form the two-ended system equivalent such that:
  • junction Jk is the equivalent end M of the two-ended system equivalent
  • Block C selects the voltage and current phasors at the terminal Tn, the voltage phasor VjkL,VjkR at the junction to which the terminal Tn is connected, and the negative summation of the corresponding current phasors of the first and second sets of current phasors such that: VM
  • terminal Tn is the equivalent
  • Block C feeds the voltage and currents VM,VN,IM,IN of the two-ended system equivalent to Block D, which determines the fault distance using the following equation:
  • x is the distance to the end M of the two-system equivalent
  • z is the impedance per length of corresponding section, which is settable by customer
  • y is the admittance per length of corresponding section, which is settable by customer
  • / is the line length of corresponding section.
  • the topology of the power transmission scheme in the embodiment of Figure 1 is merely chosen to help illustrate the working of the invention, and that the invention is applicable to power transmission schemes based on different topologies.
  • Such power transmission schemes may include, but are not limited to, a different number of power transmissions sections, a different number of junction, a different overall number of terminals, and a different number of terminals connected to each junction.
  • the power transmission scheme of Figure 1 may form the whole of a power transmission network or part of a more complex power transmission network.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Locating Faults (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

There is provided a method of locating a fault in a power transmission scheme. The power transmission scheme includes a plurality of power transmission sections and a plurality of connection points (J0-J5), the plurality of connection points includes a first end connection point (J0), a second end connection point (J5)and at least one intermediate connection point (J1-J4), and each of the plurality of power transmission sections is arranged to interconnect a respective two of the plurality of connection points such that the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate connection point interconnects (J1-J4) a or a respective neighbouring pair of the power transmission sections. The method comprises the steps of: (i) measuring first and second end voltage phasors at the first and second end connection points (J0, J5) respectively; (ii) obtaining a first set of voltage phasors, wherein the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points that are determined based on the measured first end voltage phasor; (iii) obtaining a second set of voltage phasors, wherein the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage phasor; (iv) comparing the first and second sets of voltage phasors to identify the power transmission section or connection point corresponding to the location of the fault, wherein each voltage phasor of the first set of voltage phasors is compared to the respective voltage phasor of the second set of voltage phasors that corresponds to the same connection point.

Description

METHOD OF LOCATING A FAULT IN A POWER TRANSMISSION SCHEME
This invention relates to a method of locating a fault in a power transmission scheme, an apparatus for locating a fault in a power transmission scheme, and a power transmission scheme comprising such an apparatus. According to a first aspect of the invention, there is provided a method of locating a fault in a power transmission scheme, the power transmission scheme including a plurality of power transmission sections and a plurality of connection points, the plurality of connection points including a first end connection point, a second end connection point and at least one intermediate connection point connected between the first and second end connection points, each of the plurality of power transmission sections arranged to interconnect a respective two of the plurality of connection points such that the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate connection point interconnects a or a respective neighbouring pair of the power transmission sections, the method comprising the steps of:
(i) measuring first and second end voltage phasors at the first and second end connection points respectively;
(ii) obtaining a first set of voltage phasors, wherein the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points that are determined based on the measured first end voltage phasor;
(iii) obtaining a second set of voltage phasors, wherein the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage phasor;
(iv) comparing the first and second sets of voltage phasors to identify the power transmission section or connection point corresponding to the location of the fault, wherein each voltage phasor of the first set of voltage phasors is compared to the respective voltage phasor of the second set of voltage phasors that corresponds to the same connection point. The method of the invention not only results in efficient determination of the location of a fault in a power transmission scheme, but also is accurate due to the consideration of the distributed parameters of the power transmission scheme. In addition the method of the invention is readily scalable to accommodate different topologies of the power transmission scheme. The latter is particularly advantageous for use in a power transmission scheme with a complex layout, such as a multi-ended power transmission scheme.
The method of the invention therefore permits quick determination of the location of a fault in a power transmission scheme, which reduces the time required to locate and repair the fault and thereby minimises the downtime of the power transmission scheme.
The first and second sets of voltage phasors may be determined in various ways. For example, in embodiments of the invention, the method may further include the steps of: measuring first and second end current phasors at the first and second end connection points respectively;
obtaining the first set of voltage phasors, wherein the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points that are determined based on the measured first end voltage and current phasors;
obtaining the second set of voltage phasors, wherein the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage and current phasors.
In further embodiments of the invention, the power transmission section connected to the first connection point may be designated as a first power transmission section, the power transmission section connected to the second connection point may be designated as a second power transmission section, the or each other power transmission section connected between the or the respective neighbouring pair of intermediate connection points may be designated as an intermediate power transmission section. In such embodiments the method may further include the steps of:
measuring first and second end current phasors at the first and second end connection points respectively;
obtaining a first set of current phasors, wherein the first set of current phasors includes respective current phasors in the first, second and intermediate power transmission sections that are determined based on the measured first end voltage and current phasors;
obtaining a second set of current phasors, wherein the second set of current phasors includes respective current phasors in the first, second and intermediate power transmission sections that are determined based on the measured second end voltage and current phasors.
The first and second sets of current phasors may be used in the method of the invention to help identify the location of the fault, e.g. by calculating fault distance.
For example, the respective voltage phasors at the second and intermediate connection points of the first set of voltage phasors may be determined based on the measured first end voltage phasor and the first set of current phasors, and the respective voltage phasors at the first and intermediate connection points of the second set of voltage phasors may be determined based on the measured second end voltage phasor and the second set of current phasors.
As discussed above, the power transmission scheme may be a multi-ended power transmission scheme. For example, the power transmission scheme may further include a further power transmission section connecting the intermediate connection point to a further connection point or a plurality of further power transmission sections each connecting a respective one of the intermediate connection points to a respective one of a plurality of further connection points. For such a power transmission scheme, the method may further include the steps of:
measuring a or a respective voltage phasor at the or each further connection point; measuring a or a respective current phasor at the or each further connection point;
determining a or a respective further current phasor flowing into the corresponding intermediate connection point and in the or each further power transmission section based on the measured voltage and current phasors of the corresponding further connection point.
The or each further current phasor may be used in the method of the invention to help identify the location of the fault, e.g. by calculating the voltage and current phasors of a neighbouring connection point.
For example, the respective current phasors in the first, second and intermediate power transmission sections of the first set of current phasors may be determined based on the measured first end voltage and current phasors and the or each further current phasor, and the respective current phasors in the first, second and intermediate power transmission sections of the second set of current phasors may be determined based on the measured second end voltage and current phasors and the or each further current phasor. Furthermore, with respect to the aforementioned multi-ended power transmission scheme, the method may further include the steps of:
measuring a or a respective voltage phasor at the or each further connection point;
measuring a or a respective current phasor at the or each further connection point;
determining a or a respective further voltage phasor at the or each intermediate connection point based on the measured voltage and current phasors of the corresponding further connection point. The or each further voltage phasor may be used in the method of the invention to help identify the location of the fault, as detailed later. The steps of the method of the invention may include further sub-steps in order to better pinpoint the location of the fault in the power transmission scheme. In an exemplary preferred embodiment the step of comparing the first and second sets of voltage phasors may include:
obtaining a subtraction voltage phasor of each connection point, wherein the subtraction voltage phasor of each connection point is equal to the difference between the corresponding voltage phasors of the first and second sets of voltage phasors; determining the minimum amplitude value of the plurality of subtraction voltage phasors;
comparing the minimum amplitude value with a predefined criterion threshold to identify the power transmission section or connection point corresponding to the location of the fault.
In embodiments of the invention based on the use of the minimum amplitude value, the step of comparing the first and second sets of voltage phasors may include:
if the minimum amplitude value is less than the predefined criterion threshold, comparing the voltage phasor and further voltage phasor of the intermediate connection point to determine whether the location of the fault is on the intermediate connection point or in the further power transmission section corresponding to the minimum amplitude value.
In further embodiments of the invention based on the use of the minimum amplitude value, the step of comparing the first and second sets of voltage phasors further includes:
if the minimum amplitude value is more than the predefined criterion threshold, comparing the voltage phasors of the connection point corresponding to the minimum amplitude value with the voltage phasors of a neighbouring connection point to identify the power transmission section corresponding to the location of the fault. In such embodiments, the step of comparing the first and second sets of voltage phasors further includes: if the minimum amplitude value is more than the predefined criterion threshold, comparing the phase or amplitude of the subtraction voltage phasor of the connection point corresponding to the minimum amplitude value with the phase or amplitude of the subtraction voltage phasor of a neighbouring connection point to identify the power transmission section corresponding to the location of the fault.
If a given power transmission section is identified as the location of the fault, the method may further include the step of using the corresponding voltages and currents to form a two-ended system equivalent of the power transmission section identified as the location of the fault. In such embodiments the method may further include the step of determining the distance of the fault along the power transmission section on the basis of the voltage and currents of the two-ended system equivalent.
According to a second aspect of the invention, there is provided an apparatus for locating a fault in a power transmission scheme, the power transmission scheme including a plurality of power transmission sections and a plurality of connection points, the plurality of connection points including a first end connection point, a second end connection point and at least one intermediate connection point connected between the first and second end connection points, each of the plurality of power transmission sections arranged to interconnect a respective two of the plurality of connection points such that the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate connection point interconnects a or a respective neighbouring pair of the power transmission sections, the apparatus configured to:
(i) measure first and second end voltage phasors at the first and second end connection points respectively;
(ii) obtain a first set of voltage phasors, wherein the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points that are determined based on the measured first end voltage phasor;
(iii) obtain a second set of voltage phasors, wherein the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage phasor;
(iv) compare the first and second sets of voltage phasors to identify the power transmission section or connection point corresponding to the location of the fault, wherein each voltage phasor of the first set of voltage phasors is compared to the respective voltage phasor of the second set of voltage phasors that corresponds to the same connection point.
According to a third aspect of the invention, there is provided a power transmission scheme including a plurality of power transmission sections and a plurality of connection points, the plurality of connection points including a first end connection point, a second end connection point and at least one intermediate connection point connected between the first and second end connection points, each of the plurality of power transmission sections arranged to interconnect a respective two of the plurality of connection points such that the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate connection point interconnects a or a respective neighbouring pair of the power transmission sections, wherein the power transmission scheme further includes the apparatus of the second aspect of the invention.
The features and advantages of the method of the first aspect of the invention and its embodiments apply mutatis mutandis to the apparatus of the second aspect of the invention and the power transmission scheme of the third aspect of the invention and its embodiments. Accordingly optional features of the method of the first aspect of the invention may be applied correspondingly to the apparatus of the second aspect of the invention and the power transmission scheme of the third aspect of the invention and its embodiments.
It will also be appreciated that the use of the terms "first" and "second" in the patent specification is merely intended to help distinguish between similar features (e.g. the first and second sets of voltage phasors), and is not intended to indicate the relative importance of one feature over another feature. A preferred embodiment of the invention will now be described, with reference to a non-limiting example, with reference to the accompanying drawings in which: Figure 1 shows a schematic representation of the topology of a power transmission scheme according to an embodiment of the invention;
Figure 2 shows a schematic representation of an apparatus forming a part of the power transmission scheme of Figure 1;
Figure 3 illustrates a voltage profile along the power transmission scheme of Figure 1 during the occurrence of a fault; and
Figure 4 shows a flow diagram which illustrates steps in a method of locating a fault in the power transmission scheme of Figure 1.
A fault may occur during the operation of a power transmission scheme, thus potentially resulting in downtime in order to ensure the safety of the power transmission scheme and its users. Such downtime however prevents electricity from being supplied via the power transmission scheme. This not only inconveniences end consumers reliant on the electricity transmitted via the power transmission scheme but also results in economic damages to the operator of the power transmission scheme.
Restoration of the power transmission scheme to working order requires the repair of the fault, which preferably requires the rapid determination of the location of the fault in the power transmission scheme in order to minimise the length of the downtime. A power transmission scheme according to an embodiment of the invention is shown in Figure 1.
The power transmission scheme comprises a plurality of power transmission sections and a plurality of connection points. Each connection point is in the form of a junction. The plurality of junctions includes a first end junction, a second end junction and a plurality of intermediate junctions connected between the first and second end junctions. In Figure 1 the first end junction is indicated as J0, the second end junction is indicated as J5, and the intermediate junctions are respectively indicated as J1, J2, J3 and J4.
A first of the power transmission sections is connected between junctions J0 and J1. A second of the power transmission sections is connected between junctions J4 and J5. The three remaining power transmission sections are intermediate power transmission sections connected between junctions J1 and J2, between junctions J2 and J3 and between junctions J3 and J4 respectively. In this manner each of the plurality of power transmission sections is arranged to interconnect a respective two of the plurality of junctions J0,J1,J2,J3,J4,J5 such that the plurality of power transmission sections are connected successively between the first and second end junctions J0,J5 and such that each intermediate junction J1,J2,J3,J4 interconnects a respective neighbouring pair of the power transmission sections.
The junction J0 is directly connected to a first terminal Tl . The junction J5 is directly connected to a second terminal T6.
The power transmission scheme further includes a plurality of further power transmission sections. The junction J1 is connected to a third terminal T2 via a first, further power transmission section, the junction J2 is connected to a third terminal T3 via a second, further power transmission section, the junction J3 is connected to a third terminal T4 via a third, further power transmission section, and the junction J4 is connected to a third terminal T5 via a fourth, further power transmission section.
The power transmission scheme further includes an apparatus that comprises a plurality of blocks A, B, C and D, as shown in Figure 2. A method of locating a fault in the power transmission scheme of Figure 1 will now be described as follows, with reference to Figures 1 to 4.
In general the method of the invention is based on the measurement of the voltage phasors at the junctions J0 and J5, the calculation of the voltage phasors in the rest of the power transmission scheme based on the measured voltage phasors, and the comparison of the voltage phasors. For example, if the fault is located between junctions J2 and J3, the voltage at the point of fault calculated based on the voltage phasor at the junction J0 is the same as the voltage at the point of fault calculated based on the voltage phasor at the junction J5. Figure 3 illustrates the voltage profile along the power transmission scheme of Figure 1 during the occurrence of a fault.
More particularly the method of the invention includes the following steps. Initially voltage phasors
Figure imgf000012_0001
are measured at the terminals T1,T2,T3,T4,T5,T6 respectively, and current phasors are measured
Figure imgf000012_0002
at the terminals T1,T2,T3,T4,T5,T6 respectively.
The measured voltage and current phasors are then fed into Block A of the apparatus to calculate: first and second sets of voltage phasors at the junctions; first and second sets of current phasors in the power transmission sections interconnecting the junctions; and further voltage phasors at the junctions.
The following steps are based on J0 as a starting point and J5 as an end point. It is envisaged that, in other embodiments of the invention, the following steps are based on J5 as a starting point and J0 as an end point. It is also envisaged that, in still other embodiments of the invention, T2 may be used in place of J0 as a starting point and/or T5 may be used in place of J5 as an end point. The selection of the starting and end points can be indicated by a topology matrix representing the topology of the power transmission scheme, which is settable and inputted by a user. The topology matrix is defined as follows:
Figure imgf000013_0001
Figure imgf000013_0014
The number of rows in the topology matrix equals the number of terminals so that each row of the topology matrix represents each terminal, and the number of columns in the topology matrix equals the number of junctions so that each column of the topology matrix represents each junction. Thus, if the mth terminal is connected with nth junction, then the mth row, nth column of the matrix is set as 1 ; if the mth terminal is not connected with nth junction, then the mth row, nth column of the matrix is set as 0.
Moving from J0 to J5 (left to right in Figure 1), the first sets of voltage and current phasors are determined.
In the first set of voltage phasors VJL, the voltage phasor at junction
Figure imgf000013_0011
the vo ltage phasor at junction
Figure imgf000013_0002
the voltage phasor at junction
Figure imgf000013_0012
the voltage phasor at junction
Figure imgf000013_0003
the voltage phasor at junction and the voltage
Figure imgf000013_0013
phasor at junction
Figure imgf000013_0004
In the first set of current phasors
Figure imgf000013_0005
the current in the power transmission section between junctions
Figure imgf000013_0006
, the current in the power transmission section between junctions
Figure imgf000013_0007
the current in the power transmission section between junctions
Figure imgf000013_0008
L, the current in the power transmission section between junctions
Figure imgf000013_0009
and the current in the power transmission section between junctions
Figure imgf000013_0010
The voltage phasor
Figure imgf000014_0004
at junction J0 is equal to the measured voltage phasor V
Figure imgf000014_0003
at terminal Tl, and the current I in the power transmission section between junctions
Figure imgf000014_0005
J0 and J1 is equal to the current phasor Ιτι measured at the terminal Tl .
Figure imgf000014_0001
Each of the other voltage phasors at the respective junction
Figure imgf000014_0010
Figure imgf000014_0009
is calculated based on the voltage phasor of the preceding junction and the current phasor of the preceding power transmission section. Each of the other current phasors L in the respective power transmission sections are
Figure imgf000014_0008
based on the voltage phasor of the preceding junction, the current phasor of the preceding power transmission section, and the current phasor in the further power transmission medium connected to the preceding junction.
Figure imgf000014_0006
where k ranges from 1 to 5;
Figure imgf000014_0002
is the impedance per length of the power transmission section
Figure imgf000014_0007
interconnecting the k- lth junction to the kth junction;
Figure imgf000015_0002
the admittance per length of the power transmission section interconnecting the k- lth junction to the kth junction; is the line length of the power transmission section interconnecting
Figure imgf000015_0003
the k- lth junction to kth the junction;
Figure imgf000015_0004
is the nth-terminal-to-kth-junction current flowing in the further power transmission medium connected to the kth junction.
Moving from h to J1 (right to left in Figure 1), the second sets of voltage and current phasors are determined.
In the second set of voltage phasors VJR, the voltage phasor at junction
Figure imgf000015_0016
the voltage phasor at junction
Figure imgf000015_0005
the voltage phasor at junction the voltage
Figure imgf000015_0008
phasor at junction
Figure imgf000015_0006
the voltage phasor at junction and the voltage phasor at junction
Figure imgf000015_0009
Figure imgf000015_0007
In the second set of current phasors
Figure imgf000015_0010
the current in the power transmission section between junctions
Figure imgf000015_0011
the current in the power transmission section between junctions
Figure imgf000015_0012
the current in the power transmission section between junctions
Figure imgf000015_0013
the current in the power transmission section between junctions
Figure imgf000015_0014
and the current in the power transmission section between junctions
Figure imgf000015_0015
The voltage phasor
Figure imgf000015_0017
at junction J6 is equal to the measured voltage phasor
Figure imgf000015_0019
S at terminal T5, and the current
Figure imgf000015_0018
in the power transmission section between junctions J4 and J5 is equal to the current phasor Ιτ6 measured at the terminal T6.
Figure imgf000015_0001
Each of the other voltage phasors at the respective junction
Figure imgf000016_0007
Figure imgf000016_0006
is calculated based on the voltage phasor of the preceding junction and the current phasor of the preceding power transmission section. Each of the other current phasors
Figure imgf000016_0008
in the respective power transmission sections are based on the voltage phasor of the preceding junction, the current phasor of the preceding power transmission section, and the current phasor in the further power transmission medium connected to the preceding junction.
Figure imgf000016_0001
where,
Figure imgf000016_0002
Figure imgf000016_0003
is the impedance per length of the power transmission section interconnecting the k+ lth junction to kth junction; is the admittance per length of the power transmission section
Figure imgf000016_0004
interconnecting the k+ lth junction to the kth junction;
Figure imgf000016_0005
k is the line length of the power transmission section interconnecting the k+ lth junction to the kth junction;
Figure imgf000017_0015
is the nth-terminal-to-kth-junction current flowing in the further power transmission medium connected to the kth junction.
In the further voltage phasors VJT, the further voltage phasor at junction
Figure imgf000017_0006
the further voltage phasor at junction
Figure imgf000017_0013
, the further voltage phasor at junction
Figure imgf000017_0007
Figure imgf000017_0014
and the further voltage phasor at junction
Figure imgf000017_0005
Further current phasors in the respective further power transmissions sections are also calculated. In the further current phasors IJT, the current in the further power transmission section between junction J1 and terminal
Figure imgf000017_0008
the current in the further power transmission section between junction
Figure imgf000017_0009
and terminal
Figure imgf000017_0010
the current in the further power transmission section between junction and terminal T4
Figure imgf000017_0011
is and the current in the further power transmission section between junction
Figure imgf000017_0004
Figure imgf000017_0012
and terminal T5 is
Figure imgf000017_0003
The further voltage and current phasors for junction J1 with respect to terminal T2 are calculated by the following equations:
Figure imgf000017_0001
where,
Figure imgf000017_0002
is the impedance per length of the further power transmission section
Figure imgf000018_0005
interconnecting junction J1 to terminal T2; is the admittance per length of the further power transmission section
Figure imgf000018_0001
interconnecting junction J1 to terminal T2; is the line length of the further power transmission section interconnecting
Figure imgf000018_0006
junction J1 to terminal T2.
The further voltage and current phasors for junction with respect to terminal T3 are
Figure imgf000018_0010
calculated by the following equations:
Figure imgf000018_0002
where,
Figure imgf000018_0003
Figure imgf000018_0007
is the impedance per length of the further power transmission section interconnecting junction to terminal T3;
Figure imgf000018_0008
is the admittance per length of the further power transmission section
Figure imgf000018_0004
interconnecting junction to terminal T3;
Figure imgf000018_0009
Figure imgf000019_0006
is the line length of the further power transmission section interconnecting junction to terminal T3.
The further voltage and current phasors for junction J3 with respect to terminal T4 are calculated by the following equations:
Figure imgf000019_0001
where,
Figure imgf000019_0002
Figure imgf000019_0003
is the impedance per length of the further power transmission section interconnecting junction J3 to terminal T4;
Figure imgf000019_0004
is the admittance per length of the further power transmission section interconnecting junction J3 to terminal T4;
Figure imgf000019_0005
is the line length of the further power transmission section interconnecting junction to terminal T4.
The further voltage and current phasors for junction J4 with respect to terminal T5 are calculated by the following equations: where,
Figure imgf000020_0001
is the impedance per length of the further power transmission section interconnecting junction J4 to terminal T5; is the admittance of the further power transmission section interconnecting
Figure imgf000020_0003
junction J4 to terminal T5; is the line length of the further power transmission section interconnecting
Figure imgf000020_0004
junction J4 to terminal T5).
The first and second sets of voltage phasors VJL,VVR and the further voltage phasors VJT are then fed into Block B to compare the voltage phasors to identify the power transmission section or junction corresponding to the location of the fault, as follows. The following steps are illustrated in the flow diagram of Figure 4.
A subtraction voltage phasor for each junction is obtained. In this regard the subtraction voltage phasor of each junction is equal to the difference between the corresponding voltage phasors of the first and second sets of voltage phasors VJL,VJR, as shown in the following equation.
Figure imgf000021_0001
Then the minimum amplitude value (modular) ΔVmin of the plurality of subtraction voltage phasors ΔVj is determined using the equation: ΔVmin =
Figure imgf000021_0005
0,1,2,3,4,5} .
The minimum amplitude value ΔVmin is subsequently compared with a predefined voltage threshold Vthresl to determine whether ΔVmin is less than Vthresl . In Figure 4, Vthresl is exemplarily set at 0.02 times ofthe rated voltage ofthe power transmission scheme so that, for example, if the rated voltage is 110 V, then Vthresl is 2.2 V.
If the minimum amplitude value ΔVmin is less than the predefined voltage threshold Vthresl, it indicates that the fault is either on the junction corresponding to the minimum amplitude value ΔVmin or in the further power transmission section connected to this junction. For example, if
Figure imgf000021_0002
it indicates that the fault is either on the junction J3 or in the further power transmission section interconnecting the junction J3 and the terminal T4.
Subsequently the location of the fault is more accurately determined by using the discriminative criterion of Vthres2, where Therefore, for
Figure imgf000021_0004
example, if
Figure imgf000021_0003
the discriminative criterion is In
Figure imgf000021_0006
Figure 4, Vthresl is exemplarily set at 0.05 times of the rated voltage of the power transmission scheme so that, for example, if the rated voltage is 110 V, then Vthresl is 5.5 V. If |VjkL-Vjk τη| > Vthres2, then the fault is located in the further power transmission section interconnecting the kth junction and the nth terminal. If |VjkL-Vjk τη| <= Vthres2, then the fault is located on the kth junction. If there are multiple terminals connected to the junction in question, the discriminative criterion is applied to each terminal in turn.
If the minimum amplitude value ΔVmin is more than the predefined voltage threshold Vthresl, it indicates that the fault is in the power transmission section interconnecting the kth junction and the k+ lth junction. For example, if it indicates that
Figure imgf000022_0001
the fault is in the power transmission sections interconnecting the junctions
Figure imgf000022_0002
Subsequently the location of the fault is more accurately determined by comparing the voltage phasor of a given junction with the voltage phasor of a neighbouring junction to identify the power transmission section corresponding to the location of the fault. Different criterion may be applied to determine the power transmission section in which the fault is located.
In a first exemplary criterion, the power transmission section in which the fault is located is determined by comparing the phases of the subtraction voltage phasor
Figure imgf000022_0005
of a given junction and the subtraction voltage phasor Δ
Figure imgf000022_0004
of a neighbouring junction to check whether the comparison meets the followin criterion:
Figure imgf000022_0003
If the criterion is met, then the fault is located in the power transmission section interconnecting junctions Jk and Jk+i .
In a second exemplary criterion, the power transmission section in which the fault is located is determined by comparing the amplitudes of the subtraction voltage phasor ΔVjk of a given junction and the subtraction voltage phasor ΔVjk+i of a neighbouring junction to check whether an am litude comparison meets the following criterion:
Figure imgf000023_0001
where ει is the threshold with per-unit value. For example, ει = -0.01 .
If the criterion is met, then the fault is located in the power transmission section interconnecting junctions Jk and Jk+i .
In a third exemplary criterion, the power transmission section in which the fault is located is determined by comparing the subtraction voltage phasor ΔVjk of a given junction and the subtraction voltage phasor ΔVjk+i of a neighbouring junction to check whether the comparison meets the following criterion.
Figure imgf000023_0002
If the criterion is met, then the fault is located in the power transmission section interconnecting junctions Jk and Jk+i .
If a given power transmission section is identified as the location of the fault, Block C then selects the appropriate voltage and current phasors from VJL, VJR, IJL and IJR and forms a two-ended system equivalent of the power transmission section identified as the location of the fault with voltages and currents VM, VN, IM, IN.
If the relevant power transmission section is connected between junctions Jk and Jk+i , the voltage and current phasors
Figure imgf000023_0003
are selected to form the two-ended system equivalent such that:
Figure imgf000023_0004
That is, junction Jk is the equivalent end M of the two-ended system equivalent,
Figure imgf000023_0005
and junction Jk+i is the equivalent N of the two-ended system equivalent. If the relevant power transmission section is a further power transmission section interconnecting a junction Jk and a terminal Tn, Block C then selects the voltage and current phasors at the terminal Tn, the voltage phasor VjkL,VjkR at the junction to which the terminal Tn is connected, and the negative summation of the corresponding current phasors of the first and second sets of current phasors
Figure imgf000024_0005
such that: VM
That is, terminal Tn is the equivalent
Figure imgf000024_0004
end M of the two-ended system equivalent, and junction Jk is the equivalent end N of the two-ended system equivalent. Based on the two-ended system equivalent the distance of the fault along the power transmission section is determined on the basis of the voltage and currents VM,VN,IM,IN of the two-ended system equivalent. In the apparatus of Figure 2, Block C feeds the voltage and currents VM,VN,IM,IN of the two-ended system equivalent to Block D, which determines the fault distance using the following equation:
Figure imgf000024_0002
where
x is the distance to the end M of the two-system equivalent;
Figure imgf000024_0001
z is the impedance per length of corresponding section, which is settable by customer;
y is the admittance per length of corresponding section, which is settable by customer;
/ is the line length of corresponding section.
The above equation can be simplified as:
Figure imgf000024_0003
In the foregoing manner the method of the invention permits the determination of the location of a fault in a power transmission scheme.
It will be appreciated that the topology of the power transmission scheme in the embodiment of Figure 1 is merely chosen to help illustrate the working of the invention, and that the invention is applicable to power transmission schemes based on different topologies. Such power transmission schemes may include, but are not limited to, a different number of power transmissions sections, a different number of junction, a different overall number of terminals, and a different number of terminals connected to each junction.
It is evident from the foregoing description of the method of locating a fault in the power transmission scheme of Figure 1 that the method of the invention is readily scalable to accommodate different topologies of the power transmission scheme.
It will be also appreciated that the power transmission scheme of Figure 1 may form the whole of a power transmission network or part of a more complex power transmission network.
It will be further appreciated that the values for the parameters described herein are merely chosen to help illustrate the working of the invention, and that these values may vary depending on the application of the power transmission scheme.

Claims

CLAIMS:
1. A method of locating a fault in a power transmission scheme, the power transmission scheme including a plurality of power transmission sections and a plurality of connection points (J0-J5), the plurality of connection points including a first end connection point (J0), a second end connection point (J5) and at least one intermediate connection point (J1-J4) connected between the first and second end connection points (J0, J5), each of the plurality of power transmission sections arranged to interconnect a respective two of the plurality of connection points (J0-J5) such that the plurality of power transmission sections are connected successively between the first and second end connection points (J0, J5) and such that the or each intermediate connection point interconnects (J1-J4), or a respective neighbouring pair of the power transmission sections, the method comprising the steps of:
(i) measuring first and second end voltage phasors at the first and second end connection points (J0, J5) respectively;
(ii) obtaining a first set of voltage phasors, wherein the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points that are determined based on the measured first end voltage phasor;
(iii) obtaining a second set of voltage phasors, wherein the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage phasor;
(iv) comparing the first and second sets of voltage phasors to identify the power transmission section or connection point corresponding to the location of the fault, wherein each voltage phasor of the first set of voltage phasors is compared to the respective voltage phasor of the second set of voltage phasors that corresponds to the same connection point.
2. A method according to Claim 1, further including the steps of: measuring first and second end current phasors at the first and second end connection points respectively;
Figure imgf000027_0004
obtaining the first set of voltage phasors, wherein the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points that are determined based on the measured first end voltage and current phasors; obtaining the second set of voltage phasors, wherein the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage and current phasors.
3. A method according to any one of the preceding claims, wherein the power transmission section connected to the first connection point (J0) is a first power transmission section, the power transmission section connected to the second connection point
Figure imgf000027_0002
( ) is a second power transmission section, the or each other power transmission section connected between the or the respective neighbouring pair of intermediate connection points is an intermediate power transmission section,
Figure imgf000027_0001
the method further including the steps of: measuring first and second end current phasors at the first and second end connection points ) respectively;
Figure imgf000027_0003
obtaining a first set of current phasors, wherein the first set of current phasors includes respective current phasors in the first, second and intermediate power transmission sections that are determined based on the measured first end voltage and current phasors; obtaining a second set of current phasors, wherein the second set of current phasors includes respective current phasors in the first, second and intermediate power transmission sections that are determined based on the measured second end voltage and current phasors.
4. A method according to Claim 3, wherein the respective voltage phasors at the second and intermediate connection points of the first set of voltage phasors are determined based on the measured first end voltage phasor and the first set of current phasors, and the respective voltage phasors at the first (J0) and intermediate connection points (J1-J4) of the second set of voltage phasors are determined based on the measured second end voltage phasor and the second set of current phasors.
5. A method according to any one of the preceding claims, wherein the power transmission scheme further includes a further power transmission section connecting the intermediate connection point to a further connection point or a plurality of further power transmission sections each connecting a respective one of the intermediate connection points to a respective one of a plurality of further connection points, the method further including the steps of: measuring a or a respective voltage phasor at the or each further connection point; measuring a or a respective current phasor at the or each further connection point; determining a or a respective further current phasor flowing into the corresponding intermediate connection point and in the or each further power transmission section based on the measured voltage and current phasors of the corresponding further connection point.
6. A method according to Claim 5, when dependent from Claim 3 or Claim 4, wherein the respective current phasors in the first, second and intermediate power transmission sections of the first set of current phasors are determined based on the measured first end voltage and current phasors and the or each further current phasor, and the respective current phasors in the first, second and intermediate power transmission sections of the second set of current phasors are determined based on the measured second end voltage and current phasors and the or each further current phasor.
7. A method according to any one of the preceding claims, wherein the power transmission scheme further includes a further power transmission section connecting the intermediate connection point to a further connection point or a plurality of further power transmission sections each connecting a respective one of the intermediate connection points to a respective one of a plurality of further connection points, the method further including the steps of: measuring a or a respective voltage phasor at the or each further connection point; measuring a or a respective current phasor at the or each further connection point; determining a or a respective further voltage phasor at the or each intermediate connection point based on the measured voltage and current phasors of the corresponding further connection point.
8. A method according to any one of the preceding claims, wherein the step of comparing the first and second sets of voltage phasors includes: obtaining a subtraction voltage phasor of each connection point, wherein the subtraction voltage phasor of each connection point is equal to the difference between the corresponding voltage phasors of the first and second sets of voltage phasors; determining the minimum amplitude value of the plurality of subtraction voltage phasors; comparing the minimum amplitude value with a predefined criterion threshold to identify the power transmission section or connection point corresponding to the location of the fault.
9. A method according to Claim 8, when dependent from Claim 7, wherein the step of comparing the first and second sets of voltage phasors includes: if the minimum amplitude value is less than the predefined criterion threshold, comparing the voltage phasor and further voltage phasor of the intermediate connection point to determine whether the location of the fault is on the intermediate connection point or in the further power transmission section corresponding to the minimum amplitude value.
10. A method according to Claim 8 or Claim 9, wherein the step of comparing the first and second sets of voltage phasors further includes: if the minimum amplitude value is more than the predefined criterion threshold, comparing the voltage phasors of the connection point corresponding to the minimum amplitude value with the voltage phasors of a neighbouring connection point to identify the power transmission section corresponding to the location of the fault.
11. A method according to Claim 10, wherein the step of comparing the first and second sets of voltage phasors further includes: if the minimum amplitude value is more than the predefined criterion threshold, comparing the phase or amplitude of the subtraction voltage phasor of the connection point corresponding to the minimum amplitude value with the phase or amplitude of the subtraction voltage phasor of a neighbouring connection point to identify the power transmission section corresponding to the location of the fault.
12. A method according to any one of the preceding claims, further including the step of: if a given power transmission section is identified as the location of the fault, using the corresponding voltages and currents to form a two-ended system equivalent of the power transmission section identified as the location of the fault.
13. A method according to Claim 12, further including the step of determining the distance of the fault along the power transmission section on the basis of the voltage and currents of the two-ended system equivalent.
14. An apparatus for locating a fault in a power transmission scheme, the power transmission scheme including a plurality of power transmission sections and a plurality of connection points
Figure imgf000031_0001
the plurality of connection points including a first end connection point (J0), a second end connection point
Figure imgf000031_0006
and at least one intermediate connection point connected between the first and second end
Figure imgf000031_0002
connection points each of the plurality of power transmission sections arranged
Figure imgf000031_0003
to interconnect a respective two of the plurality of connection points such that
Figure imgf000031_0007
the plurality of power transmission sections are connected successively between the first and second end connection points and such that the or each intermediate
Figure imgf000031_0004
connection point (J0-J5) interconnects a or a respective neighbouring pair of the power transmission sections, the apparatus configured to:
(i) measure first and second end voltage phasors at the first and second end connection points respectively;
Figure imgf000031_0005
(ii) obtain a first set of voltage phasors, wherein the first set of voltage phasors includes the measured first end voltage phasor and further includes respective voltage phasors at each of the second and intermediate connection points) that are determined based on the measured first end voltage phasor;
(iii) obtain a second set of voltage phasors, wherein the second set of voltage phasors includes the measured second end voltage phasor and further includes respective voltage phasors at each of the first and intermediate connection points that are determined based on the measured second end voltage phasor;
(iv) compare the first and second sets of voltage phasors to identify the power transmission section or connection point corresponding to the location of the fault, wherein each voltage phasor of the first set of voltage phasors is compared to the respective voltage phasor of the second set of voltage phasors that corresponds to the same connection point.
15. A power transmission scheme including a plurality of power transmission sections and a plurality of connection points the plurality of connection points
Figure imgf000032_0003
including a first end connection point
Figure imgf000032_0004
, a second end connection point and at
Figure imgf000032_0008
least one intermediate connection point
Figure imgf000032_0002
connected between the first and second end connection points each of the plurality of power transmission sections
Figure imgf000032_0001
arranged to interconnect a respective two of the plurality of connection points
Figure imgf000032_0007
such that the plurality of power transmission sections are connected successively between the first and second end connection points
Figure imgf000032_0006
and such that the or each intermediate connection point
Figure imgf000032_0005
interconnects a or a respective neighbouring pair of the power transmission sections, wherein the power transmission scheme further includes the apparatus of Claim 14.
PCT/EP2017/052205 2016-02-02 2017-02-02 Method of locating a fault in a power transmission scheme Ceased WO2017134136A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
CN201780009737.1A CN108603910B (en) 2016-02-02 2017-02-02 Method for locating faults in power transmission schemes
JP2018539944A JP2019503642A (en) 2016-02-02 2017-02-02 How to find faults in power transmission systems
BR112018015516A BR112018015516A2 (en) 2016-02-02 2017-02-02 method and apparatus for locating a fault in a power transmission scheme and power transmission scheme
CA3012751A CA3012751A1 (en) 2016-02-02 2017-02-02 Method of locating a fault in a power transmission scheme
US16/074,797 US10830807B2 (en) 2016-02-02 2017-02-02 Method of locating a fault in a power transmission scheme
MX2018009359A MX382920B (en) 2016-02-02 2017-02-02 METHOD OF LOCATING A FAULT IN A POWER TRANSMISSION SCHEME.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP16275017.8 2016-02-02
EP16275017.8A EP3203248B1 (en) 2016-02-02 2016-02-02 Method of locating a fault in a power transmission scheme

Publications (1)

Publication Number Publication Date
WO2017134136A1 true WO2017134136A1 (en) 2017-08-10

Family

ID=55300450

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2017/052205 Ceased WO2017134136A1 (en) 2016-02-02 2017-02-02 Method of locating a fault in a power transmission scheme

Country Status (8)

Country Link
US (1) US10830807B2 (en)
EP (1) EP3203248B1 (en)
JP (1) JP2019503642A (en)
CN (1) CN108603910B (en)
BR (1) BR112018015516A2 (en)
CA (1) CA3012751A1 (en)
MX (1) MX382920B (en)
WO (1) WO2017134136A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3662553A1 (en) * 2017-08-04 2020-06-10 ABB Power Grids Switzerland AG Method and device for fault section identification in multi-terminal mixed lines
US11035896B2 (en) * 2018-05-22 2021-06-15 Guangdong University Of Technology Method and device for reliability assessment of wide area protection system
CN109580463B (en) * 2018-11-22 2021-08-20 国网天津市电力公司电力科学研究院 A method for measuring the corrosion degree of grounding grid
CN113219298B (en) * 2021-03-24 2022-10-11 昆明理工大学 Fault current traveling wave numerical simulation method for complex alternating current power grid
WO2024251377A1 (en) * 2023-06-09 2024-12-12 Zaphiro Technologies Sa Directional fault locating in a power network

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140229127A1 (en) * 2013-02-13 2014-08-14 Alstom Grid, Inc. Electrical fault location determination in a distribution system based on phasor information

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8131485B2 (en) * 2005-09-14 2012-03-06 Abb Technology Ag Method for fault location in electric power lines
CN100549710C (en) * 2007-06-22 2009-10-14 北京四方继保自动化股份有限公司 Utilize distribution parameter to realize the two ends of electric transmission line distance-finding method
US8072715B2 (en) * 2008-07-16 2011-12-06 Huntington Ingalls Incorporated Method, apparatus and computer program product for fault protection
CN103197204B (en) * 2013-04-07 2015-04-29 山东电力集团公司德州供电公司 Mixed type method of multi-terminal circuit fault location
US9476930B2 (en) * 2014-02-07 2016-10-25 Mitsubishi Electric Research Laboratories, Inc. Locating multi-phase faults in ungrounded power distribution systems

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140229127A1 (en) * 2013-02-13 2014-08-14 Alstom Grid, Inc. Electrical fault location determination in a distribution system based on phasor information

Also Published As

Publication number Publication date
MX382920B (en) 2025-03-13
CA3012751A1 (en) 2017-08-10
CN108603910B (en) 2021-08-24
JP2019503642A (en) 2019-02-07
EP3203248A1 (en) 2017-08-09
CN108603910A (en) 2018-09-28
US10830807B2 (en) 2020-11-10
EP3203248B1 (en) 2023-11-22
MX2018009359A (en) 2018-12-19
US20190041448A1 (en) 2019-02-07
BR112018015516A2 (en) 2018-12-26

Similar Documents

Publication Publication Date Title
WO2017134136A1 (en) Method of locating a fault in a power transmission scheme
RU2571629C1 (en) Method and device for assessment of angle of zero-phase-sequence voltage at single line-to-ground fault
JP6242354B2 (en) Failure place analysis method and system for ungrounded distribution system
US8866487B2 (en) Directional fault sectionalizing system
CN106463945B (en) System and method for identifying faulty sections in a multiphase power network
EP2000811A1 (en) Method for determining location of phase-to-earth fault
WO2018095710A1 (en) Method of locating a fault in a power transmission scheme
US8274294B2 (en) Method and device for capturing a fault in an electrical supply grid
JP2018164363A (en) Voltage prediction method, load distribution determination method, and voltage prediction system
KR20150037415A (en) Device for state estimation of power distribution system
EP3642636B1 (en) Method for detecting impedances in an electrical power distribution grid
JP2014161208A (en) Method and system for finding electric power consumption of load
EP3299826A1 (en) Method to estimate an equivalent grid impedance for power generators
Morales-Espana et al. Fault location method based on the determination of the minimum fault reactance for uncertainty loaded and unbalanced power distribution systems
US3958153A (en) Method and apparatus for fault detection in a three-phase electric network
KR20160023630A (en) Insulation monitoring device
Hossain et al. Distribution high impedance fault location using localized voltage magnitude measurements
JP4906498B2 (en) Ground fault location method and orientation device
Kochneva et al. Impact of technical losses calculation method on bad data validation on the basis of a posteriori analysis
CN111090021A (en) A fault location method for composite low-voltage distribution network
JP6533969B2 (en) Voltage unbalance suppression support method and voltage unbalance suppression support device
EP4488696B1 (en) Fault location detection in tapped power distribution lines
EP3141918B1 (en) Improvements in or relating to determining a fault location in a power transmission medium
RU2558265C1 (en) Determination of distance to points of double earth connection at electric power transmission lines in networks with low earth currents
CN110247401B (en) A voltage compensation method and device for a controllable voltage source

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17702126

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 3012751

Country of ref document: CA

ENP Entry into the national phase

Ref document number: 2018539944

Country of ref document: JP

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: MX/A/2018/009359

Country of ref document: MX

NENP Non-entry into the national phase

Ref country code: DE

REG Reference to national code

Ref country code: BR

Ref legal event code: B01A

Ref document number: 112018015516

Country of ref document: BR

ENP Entry into the national phase

Ref document number: 112018015516

Country of ref document: BR

Kind code of ref document: A2

Effective date: 20180730

122 Ep: pct application non-entry in european phase

Ref document number: 17702126

Country of ref document: EP

Kind code of ref document: A1