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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
  • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
  • G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
  • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
  • B60L3/0069—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to the isolation, e.g. ground fault or leak current
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
  • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
  • G01R27/08—Measuring resistance by measuring both voltage and current
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L2200/00—Type of vehicles
  • B60L2200/26—Rail vehicles
• • 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
  • G01R31/005—Testing of electric installations on transport means
  • G01R31/008—Testing of electric installations on transport means on air- or spacecraft, railway rolling stock or sea-going vessels

Definitions

• the present invention relates, in general, to fields of the measurement of the impedance of a trolley catenary and, more particularly, to an apparatus for measuring the impedance of a trolley catenary and a method of localizing a fault using the apparatus, which can measure the line constants of the trolley catenary and analyze the status of a fault through an actual system without applying shocks to a power system, in order to detect a fault location when a ground fault occurs in a distribution system for supplying power, and to determine and analyze the status of variation in power flow when a protective relay is out of order.
• a power system is always supplied with voltage and exposed to external environments, so that there exists a probability that a fault occurs due to contact with foreign materials or external shocks, as well as variation in temperature, humidity and wind.
• power equipment is continuously stressed, and is then operated in abnormally harsh conditions compared to typical power equipment.
• a precise fault location must be calculated by a distance relay or a fault localization device installed in a substation.
• the impedance R+jX from a reference point to a fault location is calculated by a distance relay or fault localization device installed in a substation or a Sectioning Post (SP), and is divided by an impedance value per unit distance, so that the distance to the fault location is calculated. Therefore, it is essential to obtain a precise impedance value to detect a precise fault location or to perform the precise operation of a protective relay.
• the impedance of a trolley catenary does not linearly increase in proportion to distance, but increases (T-R short circuit impedance) while forming a mountain-shaped curve between the locations at which a Connector of a Protective Wire (CPW) (measurement point ⁇ ) and an Autotransformer (AT) (measurement point ⁇ ) are located, because the CPW or the AT is installed at a plurality of spaced locations of a feeder line (F), unlike the impedance of a typical feeder line (F) that linearly increases in proportion to distance (T-F short circuit impedance).
• CPW Protective Wire
• AT Autotransformer
• Line constants may include a serial impedance Z (resistance, inductance), parallel admittance Y (capacitance and leakage conductance), etc.
• the line impedance Z acts on a power system in series, and is thus related to fault current, voltage drop, fault localization and the correction of a protective relay.
• an object of the present invention is to provide a scheme, which safely measures and detects the impedance of all sections of a trolley catenary by effectively adjusting a ground fault current, and which easily and precisely measures the impedance of a line without applying shocks to power equipment even if a high voltage is not interrupted, or the traveling of an electric car on a railroad.
• the present invention provides an apparatus for measuring an impedance of a trolley catenary, the apparatus being installed on a crossing, which includes a pantagraph connected to a trolley line and a ground part connected through a rail and which is movable on a rail, comprising a power analysis unit disposed between the pantagraph and the ground part and adapted to measure a voltage, a current and a power factor; and a current limiter connected in series between a rear end of the power analysis unit and the ground part.
• the apparatus may further comprise an input terminal switch controlled by an overcurrent relay, the power analysis unit being connected to a line between the input terminal switch and the ground part via the overcurrent relay.
• the current limiter may be implemented using an inductor having an equivalent resistor.
• the inductor may comprise a plurality of taps to provide a variable inductance.
• the current limiter may be an inductor having an equivalent resistor coupled to a transformer through a coil connected to a motor load circuit.
• the present invention provides a method of localizing a fault using the apparatus for measuring the impedance of the trolley catenary, comprising the steps of (a) locating the trolley catenary impedance measurement apparatus at a test point; (b) measuring a voltage(V ), a current (I ), and a power factor (cos ⁇ ) through a power supply stage of the trolley catenary; (c) measuring a voltage(V ), a current (I ), and a power factor (cos ⁇ ) through a power analysis unit (P ) of the apparatus in syn- m m chronization with the step (b); and (d) determining a trolley catenary impedance (Z ) at the test point using the following equation
• the method may further comprise the steps of selecting a plurality of test points from a test target line section, and repeating the steps (a) to (d); and expressing line impedances corresponding to distances in the target line section as functions.
• the method may further comprise the step of measuring a line impedance through the power supply stage, and reading a distance corresponding to the line impedance from the functions, thus determining a fault location.
• FIG. 1 illustrates the entire electric distribution system for a railroad car
• FIG. 2 illustrates the shape of impedance relative to the distance of a trolley catenary
• FIG. 3 illustrates an embodiment of an apparatus for measuring the impedance of a trolley catenary
• FIG. 4 illustrates an equivalent circuit of an apparatus for measuring the impedance of a trolley catenary
• FIG. 5 illustrates another embodiment of an apparatus for measuring the impedance of a trolley catenary.
• FIG. 1 illustrates the entire electric distribution system for a railroad car.
• a left portion of the drawing indicates a substation which is a power supply stage, and a right portion thereof indicates a trolley catenary.
• a trolley line T, a rail R, a feeder line F, and a protective wire PW are sequentially shown from the upper portion.
• fifty thousand volts is applied as a feeding voltage
• twenty five thousand volts is used as a voltage to be applied to the trolley catenary.
• auto- transformers ATs
• the rail R has a Connector of a Protective Wire (CPW) connected to the Protective Wire (PW).
• CPW Protective Wire
• an apparatus 100 for measuring the impedance of a trolley catenary is installed on a crossing provided with a pantagraph for connecting to the trolley line T and a ground part connected through the rail R, and is constructed so that a current limiter 110, capable of adjusting the amount of current flowing between the pantagraph and the ground part, is provided to be able to measure impedance using appropriate current. Since the measurement of the impedance of the trolley catenary can be performed during the traveling of the crossing, a frequency to be used is preferably a commercial frequency.
• the current limiter 110 includes an equivalent resistor R and an inductor m connected in series between the rear end of a power analysis unit P and the ground m part.
• the inductor generates inductance and provides a reactance X , which will be described later.
• the current limiter 110 is connected in series between the pantagraph and the ground part, and includes taps formed to provide a variable inductance, thus limiting the amount of current. Accordingly, the amount of current flowing from the pantagraph to the ground part can be limited.
• the trolley catenary impedance measurement apparatus 100 is constructed such that a voltage transformer PT for transforming a high AC voltage into a low standard voltage and an input terminal switch CB controlled by an overcurrent relay OCR are provided under the pantagraph connected to the trolley line T, thus enabling the measurement apparatus 100 to be protected from overcurrent, and such that the power analysis unit P connected to the line between the input terminal switch CB and the m ground part through the overcurrent relay OCR is provided, thus individually measuring a voltage V , a current I , and a power factor cos ⁇ . m m m
• FIG. 4 illustrates a simplified impedance equivalent circuit in a state in which the trolley catenary impedance measurement apparatus, including the power analysis unit P of FIG. 4, is connected. If it is assumed that voltages, currents and power factors re- m spectively measured by the power analysis units P and P , are V , I , and cos ⁇ , and V , I , and cos ⁇ , the following Equations: m m m
• V m (R m +jX m )I m
• R1 +jX1 is determined using the measured values V 1 , I1 , and cos ⁇ l and Vm , Im , and cos ⁇ .
• test results can be expressed as functions of line impedances relative to distance in the target line section.
• the power supply stage measures line impedance and reads a distance corresponding to the line impedance from the functions, thus determining a fault location.
• the impedance measurement apparatus are operated to be synchronized with each other. Further, the function of allowing the values measured by the power analysis unit P to be received in real time by the power analysis unit P of the impedance measurement apparatus through communication, and calculating the impedance at the location through which the trolley catenary impedance measurement apparatus passes, is provided. Contrary to the above method, it is possible for the power analysis unit P of the substation to calculate the data measured by the power analysis unit P of the m measurement apparatus, and it is also possible to synchronize the power analysis unit P of the substation and the power analysis unit P of the measurement apparatus with
• impedance values relative to distances calculated at corresponding locations can be expressed as a distance-impedance graph and can be used as the impedance trace of an actual system.
• the impedance values can be calculated for respective orders of harmonics.
• FIG. 5 illustrates an example of the installation of the measurement apparatus of the present invention in an electric car in travel, which shows that a current limiter 110, implemented using an inductor that has an equivalent resistor coupled to a transformer through a coil, is connected to the motor load circuit of the electric car.
• a transformer PT and a current transformer CT installed in the control device of the electric car can be used for the purpose of this invention, so that the load current and load factor of the electric car measured by the power analysis unit P are compared to data measured by the power analysis unit P installed in a substation, on the basis of the voltage of a load stage.
• the complex impedance of the trolley catenary is calculated by summing the impedance at the location, through which the electric car passes, and the impedance at the location (substation), at which P is installed, using the same method as the trolley catenary impedance measurement method. Impedance values relative to distances at respective locations are calculated in association with the distances between the passing locations of the electric car and the starting point thereof, and thus an impedance trace based on the impedance values is created and utilized.
• the present invention is advantageous in that it adjusts an actual fault current, which is currently being activated, thus measuring the impedance of the trolley catenary.
• the present invention is advantageous in that it adjusts an actual fault current, which is currently being activated, thus measuring the impedance of a trolley catenary.
• the calculation of a line impedance is difficult in a power feed system, such as for an electric railroad, so that the line resistance and reactance, which will appear when a fault occurs, are detected using the apparatus and method of the present invention, and impedances corresponding to respective locations are arranged into a database, thus precisely detecting a fault location and perfectly protecting the protection sections of a distance relay when a fault occurs.
• the present invention can also be usefully applied to a typical high voltage distribution system as well as a distribution system for electric cars.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Power Engineering (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Locating Faults (AREA)
• Measurement Of Resistance Or Impedance (AREA)
• Emergency Protection Circuit Devices (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=39200651

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (11)

Family Cites Families (9)

• 2006
  • 2006-09-21 KR KR1020060091608A patent/KR100821702B1/ko not_active Expired - Fee Related
• 2007
  • 2007-04-09 WO PCT/KR2007/001708 patent/WO2008035841A1/en not_active Ceased
  • 2007-04-09 EP EP07745871A patent/EP2082248A4/de not_active Withdrawn

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