JP7514472B2 - Wire short circuit confirmation device and wire short circuit confirmation method - Google Patents

Description

The present invention relates to a line short-circuit confirmation device and a line short-circuit confirmation method for an AT feeding circuit of an AC electric railway, and more specifically, to a line short-circuit confirmation device and a line short-circuit confirmation method that can easily determine whether the overhead lines are in a sound state after construction such as replacing feeder wires, contact wires, and protective wires as overhead lines of an AT feeding circuit of an AC feeding circuit for electric railways, that is, whether the overhead lines arranged so as to cross each other in two dimensions are in a sound state in which they are separated in three dimensions, or in a short-circuited state in which they are in contact.

Conventionally, AC electric railway overhead lines have two types of feeding circuits: BT feeding circuits that use suction transformers and AT feeding circuits that use autotransformers to reduce electromagnetic induction interference to proximity communication lines. In BT feeding circuits, suction transformers are inserted at predetermined distances along the overhead line, for example, every 3 to 4 km, to make the primary and secondary currents of the suction transformer roughly equal, eliminating the current flowing through the rails and reducing leakage current flowing to the ground, thereby reducing electromagnetic induction interference to proximity communication lines.

On the other hand, an AT power supply circuit, which has an autotransformer inserted at a specified interval, such as every 10 km of overhead line, has a transmission voltage at the substation that is approximately twice that of a BT power supply circuit, making it useful in areas where power sources are difficult to obtain.

In addition, through intensive research, the applicant of the present application has invented the earth fault location method shown in Patent Document 1 (JP Patent Publication No. 4-299272), which has now been put to practical use. In other words, when a short circuit occurs while electricity is flowing through an existing overhead line, by using the invention of Patent Document 1, it is possible to record for a certain period of time the relationship between the current data of the fault current that flows when the fault occurs and the voltage data of the applied voltage, and to locate the location of the earth fault point from the relationship between the current data and the voltage data. This provides an indication of the location where restoration work should be carried out, thereby contributing to early restoration.

The applicant also invented a short circuit fault detection device shown in Patent Document 2 (JP Patent Publication No. 11-227503), which has been put to practical use. By using this invention, when a short circuit fault occurs during energization in an AT feeding circuit, it is possible to determine whether the overhead line in which the fault occurred is a contact wire or a feeder wire, by using the phase difference that occurs between the voltage waveform between the rail and contact wire measured at the time of the short circuit fault and the current waveform of the current flowing through the suction wire.

To prevent breakdowns, overhead lines are replaced periodically before ground faults caused by aging occur. By carrying out such planned maintenance work, preventative disaster prevention maintenance can be carried out and the overhead lines can be kept in good condition, allowing for safer and more reliable operation.

Figures 14 and 15 show two states of the AT power supply circuit after it has been replaced, with (A) being a plan view and (B) being a side view.

As shown in Figures 14 and 15, during the maintenance work, the overhead lines 90 (90a, 90b, 90c) of the AT power supply circuit are usually mounted on poles at a predetermined height, and the overhead lines 90a, 90b, 90c are wired between the poles so that they are sufficiently separated from each other with respect to the applied AC voltage.

The rewiring of the overhead line 90 is performed with the feeder 90a, trolley wire 90b, and protective wire 90c sections to be rewired disconnected from the AC power source, and each of the overhead lines to be rewired is connected to ground potential by a grounding wire (not shown) to ensure safety, so that the work is performed in a state prepared for any emergency. Next, at least one of the overhead lines 90a, 90b, and 90c is rewired, and the overhead lines 90a, 90b, and 90c are reattached to poles and connected to the existing overhead line. After the rewiring is complete, the presence or absence of abnormalities is visually confirmed, and the grounding wire is removed before electricity is turned on and normal operation is resumed.

Japanese Patent Application Laid-Open No. 4-299272 Japanese Patent Application Laid-Open No. 11-227503

However, as shown in Figures 14 and 15, the overhead wires 90a, protective wires 90c, and trolley wires 90b of the AT feeding circuit are installed in parallel at a fixed height when viewed vertically, but in some places they cross over when viewed horizontally. When replacing the overhead wires 90 in such a location, as shown in Figure 15, when installing the new overhead wires 90, the overhead wires 90a installed at a lower pole position may accidentally come into contact with the overhead wires 90c installed at a higher pole position. In such a situation, power cannot be fed from the substation, so after the work is completed, the condition of the overhead wires 90 in the work section is visually inspected and confirmed before power is fed again, but this visual inspection is extremely difficult.

In other words, because maintenance work such as replacing the overhead wires 90 is usually performed at night, visual inspections are also performed at night, making it difficult to visually check the condition of the overhead wires 90 in the dark. In other words, because the overhead wires 90 are installed at a fairly high position above the ground, contacts and short circuits between the overhead wires 90a, 90b, and 90c can be overlooked when visually inspecting them from the ground at night. When such an event occurs, contacts and short circuits between the overhead wires 90 cannot be detected until power is supplied from the substation, and a fault current is generated when power supply begins, which not only damages the overhead wires that have just been replaced, but also delays the start of the search for and removal of the fault and the start of restoration, causing significant disruption to train operations.

The overhead wire 90 is replaced in separate work sections in the AT power supply circuit, but the overhead wire 90 of the AT power supply circuit is connected to the power supply wire 90a and the contact wire 90b at regular intervals by an autotransformer. When a DC voltage is applied, a DC current flows through the autotransformer, resulting in a conductive state even if the overhead wire 90 is in a healthy state. As a result, it is not possible to confirm that the overhead wire 90 is in a healthy state using a general insulation meter.

The present invention has been made taking the above into consideration, and its purpose is to provide a line short circuit checking device and line short circuit checking method that can check the electrical state between the overhead lines in the work section immediately after the overhead line re-laying work is completed, and if an abnormality is found, can immediately begin searching for and removing the fault point and restoring the system, minimizing the impact on train operations and checking the state between the overhead lines.

To solve the above problem, the first invention provides a line short circuit confirmation device that is a device for confirming the overhead line state of an AT feeding circuit of an AC electric railway, and is characterized by comprising an AC voltage generation unit that generates an inspection AC voltage of at least one frequency between 200 Hz and 1 kHz, a switch unit that sequentially applies the inspection AC voltage generated by the AC voltage generation unit between two overhead lines among the feeder wire, the trolley wire, and the protective wire that constitute the AT feeding circuit, a current measurement unit that measures the AC current that flows between the overhead lines when the inspection AC voltage is applied between the overhead lines, a calculation processing unit that calculates the reactance between the overhead lines from the relationship between the inspection AC voltage and the AC current, and an overhead line state confirmation unit that confirms that the overhead lines are in a separated state without a short circuit because the reactance is a capacitive characteristic. (Claim 1)

The overhead lines in this invention are the feeder wires, contact wires, and protective wires of the AT feeding circuit of an AC electric railway. When periodic replacement of the overhead lines due to deterioration or the like is carried out as part of the maintenance management of these overhead lines, the replacement work is carried out by connecting a ground wire to each of the three overhead lines in a state where they are disconnected from the AC power source of the substation to ensure safety in case of an emergency. After the newly installed overhead line is pulled up to the pole position and connected to the existing overhead line, the condition of the overhead line can be checked to see if it is in good condition by using the line short circuit checking device of this invention.

The AC voltage generating unit is a power supply unit that generates an AC voltage for inspection that is high enough to supply power to flow a stable AC current when applied between two of the replaced overhead lines, and is suppressed to a voltage that will not cause damage to the overhead lines even if a short-circuit current flows. In other words, it is an AC voltage that is suppressed low for inspection purposes, rather than the high voltage of 25 kV or more required to drive a train.

The frequency of the inspection AC voltage is 200 Hz or more, which is higher than the third harmonic components that may be affected by the AC voltage for driving electric trains and the high-voltage distribution lines installed nearby, and 1 kHz or less, which is the upper limit at which the state of the overhead line can be detected. Taking into consideration that communication lines are laid near the overhead line, it is preferable that the frequency of this inspection AC voltage be avoided near the carrier frequency used for communication to avoid communication interference. It is also preferable to avoid the frequency (720 Hz) equivalent to 360 Hz and its double harmonic components generated by ripples in the full-wave rectification of three-phase AC to avoid malfunctions due to noise from nearby DC feeders.

The switch unit is a switch element for selectively connecting the test AC voltage generated by the AC voltage generator to two of the overhead lines in sequence and applying it between the two overhead lines, and can be, for example, a semiconductor switching element such as a field effect transistor, an electromagnetic relay, or the like. In addition, for example, the connection part with the overhead line is preferably provided with a connection terminal for disconnecting the ground side end of the grounding wire connected to the overhead line after construction from the grounded state and connecting it. It is also easily conceivable to omit this switch unit and have an operator manually connect it to the two overhead lines to be tested in sequence.

The current measuring unit measures the AC current flowing from the AC voltage generating unit to the overhead line, and is disposed, for example, between the AC voltage generating unit and the switch unit. Alternatively, the current measuring unit may be provided between the switch unit and each overhead line. This AC current flows while the test AC voltage is being applied, and although it is conceivable that an unstable current will flow due to a transient phenomenon in the initial stage of application of the test AC voltage, a predetermined stable AC current will flow in response to the test AC voltage applied for a short period of time, depending on the state of the overhead line.

The calculation processing unit determines the magnitude of the AC current component that is 90 degrees out of phase with the test AC voltage from the relationship between the test AC voltage and the AC current, and if this is a leading current, it can detect that it is a capacitive characteristic. Conversely, if a lagging current flows compared to the test AC voltage, it can detect that it is an inductive characteristic.

In other words, the reactance at the frequency of the applied test AC voltage can be found from the relationship between the test AC voltage applied between the overhead lines and the resulting AC current flowing between the overhead lines. If this reactance has capacitive characteristics, it can be determined that the overhead lines are separated and in a healthy state. On the other hand, if the reactance has inductive characteristics, it can be clearly determined that the overhead lines are in a short-circuit state. Furthermore, by sequentially switching the switch unit, it is possible to detect that no short circuit has occurred between different overhead lines, and after confirming that all three overhead lines are in a normal separation state and ensuring safety, the line short-circuit confirmation device can be disconnected from the overhead lines and power can be started to be supplied to the overhead lines.

When the calculation processing unit determines that there is a short circuit between any of the overhead lines, it may output a warning using an alarm generating unit that generates sound and/or display, or may output a short circuit state signal by wired or wireless communication using a communication line. A simple warning from the alarm generating unit may be one that outputs an alarm sound such as a buzzer when a short circuit state is detected, but it may also be one that displays an alarm using a display unit such as an LED or LCD, or one that outputs an alarm both by sound and display, and any of these may be used.

When an abnormality is detected between overhead lines using the line short circuit detection device of the present invention, the contact point can be quickly located and the abnormality can be removed to restore operation without starting power supply from the substation, making it possible to reliably restore a healthy state before trains start operating.

The second invention provides a line short circuit confirmation device that is a device for confirming the overhead line state of an AT feeding circuit of an AC electric railway, and is characterized by comprising an AC voltage generation unit that generates an inspection AC voltage of at least one frequency between 200 Hz and 1 kHz, a switch unit that sequentially applies the inspection AC voltage generated by the AC voltage generation unit between two overhead lines among the feeder wire, the trolley wire, and the protective wire that constitute the AT feeding circuit, a current measurement unit that measures the AC current that flows between the overhead lines when the inspection AC voltage is applied between the overhead lines, a calculation processing unit that calculates the phase angle of the inspection AC voltage with respect to the AC current, and an overhead line state confirmation unit that confirms that the overhead lines are in a separated state without a short circuit because this phase angle is a delayed angle (Claim 2).

The overhead lines in the second invention are the feeder wires, contact wires, and protective wires of the AT feeder circuit of an AC electric railway, and by using the line short circuit confirmation device of the present invention when checking whether the condition of the overhead lines is sound after the overhead line replacement work is completed, the condition of the overhead lines can be easily and reliably confirmed.

The AC voltage generating unit is a power supply unit that generates an AC voltage for inspection that can be applied between two overhead lines to ensure a stable current flow and is kept at a voltage that will not cause a breakdown in the overhead lines even if a short circuit occurs, and generates an AC voltage with a frequency of 200 Hz or more and 1 kHz or less.

The switch unit is made up of semiconductor switching elements such as field effect transistors and electromagnetic relays that selectively connect the test AC voltage generated by the AC voltage generator to two of the overhead lines in sequence and apply it between the two lines.

The current measuring unit is provided between the AC voltage generating unit and the switch unit, or between the switch unit and each overhead line, in order to measure the AC current flowing from the AC voltage generating unit to the overhead line.

The calculation processing unit calculates the phase angle of the test AC voltage with respect to the AC current from the relationship between the test AC voltage and the AC current. If the phase angle determined by this calculation is a lag, the overhead lines are separated and in a healthy state. On the other hand, if the phase angle of the test AC voltage is a lead with respect to the AC current (the AC current lags with respect to the test AC voltage), it can be clearly determined that the overhead lines are in a short circuit state. If the calculation processing unit determines that there is a short circuit between the overhead lines, it may output a warning using a sound and/or display warning means, or may output a short circuit state signal by wired or wireless communication using a communication line.

The third invention provides a line short circuit confirmation device for confirming the overhead line state of an AT feeding circuit of an AC electric railway, comprising: an AC voltage generating unit that generates inspection AC voltages of two different frequencies between 200 Hz and 1 kHz; a switch unit that sequentially applies the inspection AC voltages generated by the AC voltage generating unit between two overhead lines among the feeder wire, the contact wire, and the protection wire that constitute the AT feeding circuit; a current measuring unit that measures the AC current that flows between the overhead lines when the inspection AC voltages of the two frequencies are applied between the overhead lines; a calculation processing unit that calculates the magnitude of the impedance between the overhead lines at both frequencies from the relationship between the inspection AC voltage and the AC current; and an overhead line state confirmation unit that confirms that the overhead lines are in a separated state and not short-circuited when the magnitude of the impedance at the higher of the two frequencies is smaller than the magnitude of the impedance at the lower of the two frequencies (Claim 3).

The overhead lines in the third invention are the feeder wires, contact wires, and protective wires of the AT feeder circuit of an AC electric railway, and by using the line short circuit confirmation device of the present invention when checking whether the overhead lines are in a sound condition after the overhead line replacement work is completed, the condition of the overhead lines can be easily and reliably confirmed.

The AC voltage generating unit is a power supply unit that generates an AC voltage for inspection that can be applied between two overhead lines to allow a stable current to flow and is suppressed to a voltage level that will not cause a breakdown in the overhead lines even if a short circuit occurs, and generates AC voltages of at least two different frequencies between 200 Hz and 1 kHz. The frequency of the AC voltage for inspection can be switched according to a control signal from the calculation processing unit, for example.

The switch unit is made up of semiconductor switching elements such as field effect transistors, electromagnetic relays, etc., which selectively connect the test AC voltages of at least two frequencies generated by the AC voltage generator to two of the overhead lines in sequence and apply them between the two overhead lines.

The current measuring units are provided between the AC voltage generating unit and the switch unit, or between the switch unit and each overhead line, in order to measure the AC current flowing from the AC voltage generating unit to the overhead line. The measured AC current becomes a stable AC current with the same frequency as the frequency of the inspection AC voltage, and each of these is measured by the current measuring unit.

The calculation processing unit calculates the magnitude of impedance between the overhead lines for each frequency from the relationship between the test AC voltage and the AC current, and compares the magnitude of impedance at high frequencies with the magnitude of impedance at low frequencies. Needless to say, at this time, a control signal is output to the AC voltage generating unit to indicate the frequency of the test AC voltage to be transmitted.

Next, if the magnitude of the impedance at high frequency is smaller than the magnitude of the impedance at low frequency, it is determined that the overhead lines are in a healthy separation state with no short circuit, and if the magnitude of the impedance at high frequency is greater than the magnitude of the impedance at low frequency, it is determined that the overhead lines are short circuited. By using the magnitude of the impedance to make the determination, a clearer criterion can be obtained, improving reliability.

When the calculation processing unit detects a short circuit between the overhead lines, it may output a warning using an audible and/or visual warning means, or may output a short circuit status signal via wired or wireless communication using a communication line.

The fourth invention provides a method for checking whether the state of the overhead wires in the AT feeding circuit of an AC electric railway is sound at the work location after the re-laying work and before the start of feeding, which is characterized by generating an inspection AC voltage of at least one frequency between 200 Hz and 1 kHz, measuring the AC current flowing between the overhead wires while applying this inspection AC voltage sequentially between the grounding terminals of the grounding wires used for the re-laying work of two overhead wires among the feeder wire, the contact wire, and the protective wire that make up the AT feeding circuit, determining the impedance between the overhead wires from the relationship between the inspection AC voltage and the AC current, and confirming that the overhead wires are in a separated state and not short-circuited when this impedance is within a range that indicates a separated state (Claim 4).

The overhead lines in the fourth invention are the feeder wires, contact wires, and protective wires of the AT feeding circuit of an AC electric railway, and this is a method for checking whether the condition of the overhead lines is sound at the work site after the completion of replacement work due to deterioration of the overhead lines, etc. This method makes it possible to easily and reliably check the condition of the overhead lines by connecting two of the overhead lines in sequence and applying an inspection AC voltage of at least one frequency between 200 Hz and 1 kHz, to see whether the overhead lines are in a normal state with a distance between them, or in a short-circuited state.

If the test AC voltage is in the range of 50 to 60 Hz, which is the frequency of commercial AC power, and is close to its third harmonic components, it may cause malfunction due to the influence of high-voltage distribution lines that are often installed in parallel with the overhead lines, but by setting the frequency of the test AC voltage to 200 Hz or higher, stable measurements can be performed. In addition, if this frequency is 1 kHz or higher, there will be multiple resonance points, which will weaken the correlation between the measurement value and frequency, making it unsuitable for use.

Within the above frequency bands, when the overhead lines are in contact and short-circuited, the higher the frequency of the test AC voltage, the greater the impedance and the greater the inductive reactance, whereas when the overhead lines are in a normal separation state, the higher the frequency, the smaller the impedance and the capacitive reactance. Therefore, by determining the impedance between the overhead lines from the relationship between the AC current flowing when the test AC voltage is applied and the test AC voltage, it is possible to obtain an indicator of the state of the overhead lines (whether they are in contact or separated).

By checking the change in impedance using multiple frequencies as the inspection AC voltage, it is possible to detect the state of the overhead line more reliably, but it is also possible to check for short circuits between overhead lines simply by checking the change in impedance at one frequency or when the frequency is swept.

In other words, when the impedance between the overhead lines is within the range that indicates the overhead line separation state, it is confirmed that the overhead lines are in a separated state and not touching each other, and after confirming that the separation state is normal between all three overhead lines and ensuring safety, the line short circuit confirmation device can be disconnected from the overhead lines and power can be started to be supplied to the overhead lines.

If it is determined that there is a short circuit between the overhead lines, a warning may be output using an audible and/or visual warning means, or a short circuit status signal may be output by wired or wireless communication using a communication line. In either case, if an abnormality is detected between the overhead lines using the line short circuit confirmation method of the present invention, the contact point can be quickly located and the abnormality can be removed to restore operation without starting power feeding from the substation. The cause can be pursued until safety can be ensured using the line short circuit confirmation method, making it possible to reliably restore a healthy state before train operation begins.

1 is a diagram conceptually showing an example of an overhead line for which short circuit check is performed by the line short circuit check device according to the present invention; 1 is a diagram illustrating an example of checking the insulation state between overhead lines using a line short circuit check device according to the present invention. FIG. 1 is a diagram showing a configuration of a line short-circuit confirmation device according to a first embodiment; 4 is a diagram illustrating a line short-circuit checking method in the line short-circuit checking device shown in FIG. 3. FIG. 11 is a diagram showing frequency characteristics of the magnitude and phase angle of impedance in a state where the feeder wire and the contact wire are separated from each other. FIG. 11 is a diagram showing frequency characteristics of the magnitude and phase angle of impedance in a short-circuit state between a feeder wire and a contact wire. FIG. 11 is a diagram showing frequency characteristics of the magnitude and phase angle of impedance between the contact wire and the guard wire when they are separated from each other. FIG. 11 is a diagram showing frequency characteristics of the magnitude and phase angle of impedance in a short-circuit state between a contact wire and a protection wire. FIG. 13 is a diagram showing frequency characteristics of the magnitude and phase angle of impedance in a state in which a protection wire and a feeder wire are separated from each other. FIG. 13 is a diagram showing frequency characteristics of the magnitude and phase angle of impedance in a short-circuit state between a protection wire and a feeder. FIG. 13 is a diagram showing the configuration of a line short-circuit confirmation device according to a second embodiment. FIG. 13 is a diagram showing the configuration of a line short-circuit confirmation device according to a third embodiment. 13 is a diagram illustrating a line short-circuit checking method in the line short-circuit checking device shown in FIG. 12. FIG. 2 is a diagram for explaining the arrangement of the overhead line when the overhead line is mounted on a pole. FIG. 13 shows a short-circuit state in which the overhead line comes into contact when the overhead line is installed on a pole.

The following describes the line short circuit confirmation device and line short circuit confirmation method according to the first embodiment of the present invention, using Figures 1 to 4.

As shown in FIG. 1, the line short circuit confirmation device 1 of the present invention is a device for confirming that no short circuit faults have occurred between the overhead lines 2 after replacement and construction of the feeder wires 2a, trolley wires 2b, and protective wires 2c that constitute the overhead line 2 for the AT feeding circuit of an AC electric railway. The overhead line 2 of the AT feeding circuit is connected by autotransformers 3a, 3b, for example, every 10 km, and at a substation 4, it is connected to the AC power source 6 for driving the train in a detachable manner by, for example, circuit breakers 5a, 5b. 7 is a rail, and by providing connecting parts 7a, 7b, etc. that are connected to the protective line 2c, for example, near the AT or the midpoint between the ATs, the protective line 2c is configured to have approximately the same potential as the rail.

8 indicates the section to be rewired for renewal due to deterioration of the overhead line 2, and 9 indicates the ground wire used to rewire the overhead line 2 in the section to be rewired 8. In the following explanation, when it is necessary to distinguish between the ground wires 9 of the feeder conductor 2a, the contact wire 2b, and the protective wire 2c, the reference characters 9a, 9b, and 9c are used.

As shown in FIG. 2, the overhead lines 2 are all mounted on poles at a height of several meters to 10 meters above the ground, and 10 is a pole supporting these overhead lines 2a to 2c. 10a is an arm formed near the upper end of the pole 10 and supports the feeder line 2b and protective line 2c, and 10b is a movable bracket supporting the trolley wire 2a.

11 is a vise that is attached so as to ensure a reliable electrical connection to the rail 7, and this vise 11 is equipped with a terminal block 11a to which the ground side terminal of the ground wire 9 is connected.

As shown in FIG. 3, the line short circuit confirmation device 1 of the first embodiment is a device for confirming the state of the overhead line 2 of the AT feeding circuit of an AC electric railway, and includes a power supply unit 20, an AC voltage generating unit 21 that generates an inspection AC voltage Vt of at least one frequency between 200 Hz and 1 kHz, a switch unit 22 that sequentially applies the inspection AC voltage Vt generated by the AC voltage generating unit 21 between two overhead lines 2 of the feeding line 2a, the trolley wire 2b, and the protective wire 2c that constitute the AT feeding circuit, and a switch unit 23 that switches the detection It is equipped with a current measuring unit 23 that measures the AC current It that flows between the overhead wires 2 when an inspection AC voltage Vt is applied between the overhead wires 2, a calculation processing unit 24 that calculates the reactance X between the overhead wires 2 from the relationship between the inspection AC voltage Vt and the AC current It, an overhead wire state confirmation unit 25 that confirms that the overhead wires are in a separated state without a short circuit because this reactance X has a capacitive characteristic, a warning generating unit 26 that displays a warning when the overhead wires 2 are in a contacting state, and an operation input unit 27.

The battery constituting the power supply unit 20 is preferably a readily available general-purpose dry cell, but may also be a rechargeable secondary battery. The AC voltage generating unit 21 is an inverter that converts the power supplied from the power supply unit 20 into an AC voltage for inspection of at least one frequency between 200 Hz and 1 kHz, and the voltage is large enough to allow a stable AC current to flow when applied between the overhead wires 2, and is also small enough to prevent a large current from flowing and damaging the newly replaced overhead wires 2 if a short circuit occurs between the overhead wires 2. The signal Sv of the AC voltage for inspection Vt generated by the AC voltage generating unit 21 is output to the calculation processing unit 24.

The frequency of the test AC voltage Vt may be any frequency within the above range, but it is preferable to avoid the frequencies of carriers used for various communications and the frequencies of harmonic components that occur in the ripples of DC power lines. In this embodiment, the frequency may be selected based on the time constant of the frequency setting circuit in the AC voltage generator 21, or it may be possible to change the frequency to any frequency using a dip switch, rotary switch, etc.

The switch section 22 applies the AC voltage Vt supplied from the AC voltage generator 21 between the two overhead wires 2, and more specifically, it is a circuit that selectively connects one of the overhead wires 2 (2a, 2b, 2c) to a common potential Com using a semiconductor element such as a field effect transistor, while selectively connecting one of the remaining two overhead wires 2 to the AC voltage generator 21. By setting the magnitude of the inspection AC voltage Vt to be equal to or lower than the withstand voltage of the field effect transistor, the switch section 22 can be formed using a switching element made of a semiconductor element, which increases durability and reliability, but it goes without saying that the switch section 22 may also be formed using a contact relay, etc.

The switch unit 22 can check the mutual separation state of the three overhead lines 2a, 2b, and 2c by sequentially switching between the overhead lines 2 to which the test AC voltage Vt is applied using a control signal C from the calculation processing unit 24. In addition, it is preferable that the switch unit 22 includes terminal blocks 22a, 22b, and 22c for connecting the ground side terminal of the ground line 9, making it easy to connect the ground line 9.

The current measuring unit 23 is an ammeter that measures the current It flowing through the overhead line 2. By measuring between the AC voltage generating unit 21 and the switch unit 22, it is possible to measure the AC current It flowing between selected overhead lines 2 even if the test AC voltage Vt is selectively applied between any two of the overhead lines 2. The signal Si of the measured AC current It is output to the calculation processing unit 24.

The calculation processing unit 24 and the overhead line state confirmation unit 25 are both realized by executing a program that can be executed by an arithmetic processing device such as a microcomputer. That is, the calculation processing unit 24 inputs the signals Sv, Si of the inspection AC voltage Vt and the AC current It to a microcomputer and calculates the relationship between the inspection AC voltage Vt and the AC current It, thereby determining the reactance X of the reactive component (complex component) that is 90° out of phase with respect to the inspection AC voltage Vt.

When the reactance X of the complex component is a positive value, the AC current It flows with a delay relative to the test AC voltage Vt, so that the characteristics between the overhead lines 2 are inductive, and when the reactance X is a negative value, the AC current It flows with a lead relative to the test AC voltage Vt, so that the characteristics between the overhead lines 2 are capacitive. Note that the AC current It may not be stable immediately after the test AC voltage Vt is applied due to transient phenomena in various circuits, including between the overhead lines 2, but it stabilizes in a short time, so it is preferable to calculate the reactance once it has been confirmed that the relationship between the test AC voltage Vt and the AC current It is stable.

When the reactance X calculated by the calculation processing unit 24 has a capacitive characteristic (negative value), the overhead line state confirmation unit 25 determines that the overhead lines 2 are in a healthy separation state, and when the reactance X has an inductive characteristic (positive value), it determines that the overhead lines 2 are in contact with each other and in a short-circuit state.

The warning generating unit 26 outputs a warning to the operator by clearly indicating the short-circuited overhead lines 2. For example, it is preferable to clearly indicate the short-circuited overhead lines 2 using red light-emitting diodes 26a, 26b, and 26c arranged as shown in Figures 1 and 2, and at the same time output a warning sound using a buzzer (not shown). On the other hand, after the warning generating unit 26 has confirmed the separation state between all of the overhead lines 2, it outputs a short completion sound indicating the completion of the inspection and lights up the green light-emitting diode 26d.

The method of generating a warning by the warning generating unit 26 can be variously modified, such as displaying a message using an LCD display unit or outputting a short circuit confirmation signal and/or a separation confirmation signal, but it goes without saying that any form can be used as long as it checks the state of the overhead line 2 and outputs a warning if a short circuit occurs.

The operation input unit 27 is a button for inputting operations by an operator. In other words, when the operator presses the button of the operation input unit 27 while the grounding end of the grounding wire 9 is connected to the line short circuit confirmation device 1, the line short circuit confirmation device 1 can execute a series of sequences for confirming the state between each of the overhead lines 2.

Figure 4 is a diagram explaining the line short circuit confirmation method for confirming a line short circuit using the line short circuit confirmation device 1 of this embodiment.

As shown in FIG. 4, when the line short circuit confirmation device 1 is started by pressing a button on the operation input unit 27, the microcomputer constituting the calculation processing unit 24 executes an executable line short circuit confirmation program P, and outputs a control signal C that switches the switch unit 22 to supply the inspection AC voltage Vt from the AC voltage generator 21 between two selected overhead lines 2 from among the overhead lines 2a to 2c (step S1).

The AC voltage generating unit 21 also converts the DC power supplied from the power supply unit 20 into a test AC voltage Vt having one frequency of 200 Hz or more and 1 kHz or less, and applies this test AC voltage Vt to the overhead line 2 selected by the switch unit 22 (step S2). At the same time, the AC voltage generating unit 21 outputs a signal Sv of the test AC voltage Vt that it has generated to the calculation processing unit 24.

Next, when a stable AC current It flows between the overhead lines 2 by applying the test AC voltage Vt, the current measuring unit 23 measures this AC current It and outputs a signal Si to the calculation processing unit 24 (step S3).

The calculation processing unit 24 calculates the reactive current of the AC current It, which is 90° out of phase with respect to the AC voltage Vt, from the relationship between the test AC voltage Vt and the AC current It, and calculates the reactance X between the overhead lines based on this reactive current (step S4). At this time, if the reactance X is positive, it is a lag characteristic, and therefore an inductive characteristic, and if it is negative, it is a lead characteristic, and therefore a capacitive characteristic.

When reactance X is found, it can be determined that the state between the selected overhead lines 2 is a normal separation state because reactance X has capacitive characteristics, and if it has inductive characteristics, it can be determined that the overhead lines 2 are in contact and short-circuited (step S5). If no AC current It flows, the connection to the overhead line 2 is not established and measurement is not possible, so the operator is prompted to check the connection by a display or sound.

If the overhead lines 2 are short-circuited, a warning display can be issued to clearly indicate the short-circuited overhead lines 2, for example by lighting up the light-emitting diodes 26a to 26c constituting the warning generating unit 26 in red, and at the same time, a warning sound such as a buzzer can be generated to issue a warning (step S6). Note that if the overhead lines 2 are separated and in a normal state, the warning generating unit 26 can either not issue any warning display, or can indicate that the separation is normal by lighting up the green light-emitting diodes, issuing a short beep, or the like.

Next, it is confirmed whether the status check between all the overhead lines 2 has been completed (step S7). If there are any overhead lines 2 for which the status check has not been completed, the process returns to step S1, the switch unit 22 is switched to the overhead lines 2 for which the short circuit check has not been performed, and the processes of steps S2 to S6 are repeated. If the status check between all the overhead lines 2 has been completed, the process proceeds to the next step S8.

When the status check between all the overhead lines 2 is completed, the operator is informed of the inspection result by lighting up the green LED and sounding a short buzzer to indicate that the entire sequence for checking for short circuits has been completed (step S8).

By practicing the line short circuit confirmation method using the line short circuit confirmation device 1 configured as described above, it is possible to very easily and reliably confirm that the overhead lines 2 are separated from each other and in a normal state after connecting the rewired overhead lines 2 to the existing overhead lines. This makes it possible to start feeding electricity to the overhead lines 2 after construction with peace of mind.

The overhead line state confirmation unit 25 judges whether the state is separated or short-circuited based on whether the reactance X between the overhead lines 2 has capacitive or inductive characteristics, and since there is a clear criterion for this judgment, it is reliable.

The determination of a short circuit state based on the electrical characteristics between the overhead lines 2 can be made based on other criteria in addition to the reactance X described above.

Figures 5 to 10 show the state between the overhead lines 2, and the frequency characteristics of the magnitude of impedance |Z| and the phase difference θ of the AC voltage Vt with respect to the AC current It. Figure 5 shows the frequency characteristics when the feeder 2a and the trolley wire 2b are in a normal separation state. Figure 6 shows the frequency characteristics when the feeder 2a and the trolley wire 2b are in a short-circuit state 2 km away. Figure 7 shows the frequency characteristics when the trolley wire 2b and the guard wire 2c are in a normal separation state. Figure 8 shows the frequency characteristics when the trolley wire 2b and the guard wire 2c are in a short-circuit state 2 km away. Figure 9 shows the frequency characteristics when the guard wire 2c and the feeder 2a are in a normal separation state. Figure 10 shows the frequency characteristics when the guard wire 2c and the feeder 2a are in a short-circuit state 2 km away.

As shown in Figures 5 to 10, when the overhead wires 2 are in a normal separation state between any two of the overhead wires 2, the phase angle θ of the inspection AC voltage Vt with respect to the AC current It is a negative value, whereas when the overhead wires 2 are in contact with each other and in a short-circuit state, the phase angle θ of the inspection AC voltage Vt with respect to the AC current It is a positive value. Therefore, the state between the overhead wires 2 may be checked using this phase difference θ as a judgment criterion.

Figure 11 is a diagram showing the configuration of a wire short circuit confirmation device 30 according to the second embodiment. Note that in Figure 11, components with the same reference numerals as those in Figure 3 are the same or equivalent components, and detailed descriptions thereof will be omitted.

As shown in FIG. 11, in the line short circuit confirmation device 30 of this embodiment, 31 is a calculation processing unit that calculates the phase difference θ of the test AC voltage Vt with respect to the AC current It based on the relationship between the test AC voltage Vt applied between the overhead wires 2 and the AC current It that flows when this test AC voltage Vt is applied, and 32 is an overhead wire state confirmation unit that confirms the state between the overhead wires 2 using the phase difference θ. In this example, the overhead wire state confirmation unit 32 determines that the overhead wires 2 are separated when the phase angle θ is negative, and determines that the overhead wires 2 are short-circuited when the phase angle θ is positive.

Figure 12 is a diagram showing the configuration of a line short circuit confirmation device 40 according to a third embodiment of the present invention. In Figure 12, 41 is an AC voltage generation unit that generates an inspection AC voltage Vt with a frequency between 200 Hz and 1 kHz indicated by a frequency control signal Cf using DC power supplied from the power supply unit 20, 42 is a calculation processing unit that outputs a frequency control signal Cf to this AC voltage generation unit 41 to sequentially specify two different transmission frequencies and calculates the magnitude |Z| of the impedance Z between the overhead line 2 from the relationship between the inspection AC voltage Vt and the AC current It, and 43 is an overhead line state confirmation unit that confirms the state between the overhead line 2 using the slope obtained from the relationship between the two specified frequencies and the magnitude |Z| of the impedance Z at each frequency.

The frequency characteristics of the magnitude |Z| of the impedance Z are as shown in Figures 5 to 10, so the overhead line state confirmation unit 43 can determine that the overhead lines are in a separated state without a short circuit by the fact that the magnitude of the impedance at high frequencies is smaller than the magnitude of the impedance at low frequencies. Other points are the same as those of the line short circuit confirmation device of the first and second embodiments, so detailed explanations are omitted.

Figure 13 is a diagram explaining the line short circuit confirmation method for confirming a line short circuit using the line short circuit confirmation device 40 of the third embodiment.

As shown in FIG. 13, when the line short circuit confirmation device 1 is started by pressing a button on the operation input unit 27, the microcomputer constituting the calculation processing unit 42 executes an executable line short circuit confirmation program P1, and outputs a control signal C that switches the switch unit 22 to supply the inspection AC voltage Vt from the AC voltage generator 41 between two selected overhead lines 2 of the overhead lines 2a to 2c (step S10).

The AC voltage generating unit 41 also converts the frequency control signal Cf from the calculation processing unit 42 into a test AC voltage Vt having a specified first frequency of 200 Hz or more and 1 kHz or less, and generates the test AC voltage Vt, and applies the test AC voltage Vt between the overhead lines 2 selected by the switch unit 22 (step S11).

When a stable AC current It flows between the overhead lines 2 by applying the test AC voltage Vt of the first frequency, the current measuring unit 23 measures this AC current It and outputs a signal Si to the calculation processing unit 42 (step S12).

The calculation processing unit 42 calculates the magnitude |Z| of the impedance Z between the overhead lines 2 at the first frequency from the relationship between the test AC voltage Vt and the AC current It. (Step S13)

Next, the AC voltage generating unit 41 converts the frequency control signal Cf from the calculation processing unit 42 into a test AC voltage Vt having a specified second frequency of 200 Hz or more and 1 kHz or less, and generates the test AC voltage Vt, and applies the test AC voltage Vt between the overhead lines 2 selected by the switch unit 22 (step S14).

When a stable AC current It flows between the overhead lines 2 by applying the second frequency test AC voltage Vt, the current measuring unit 23 measures this AC current It and outputs a signal Si to the calculation processing unit 42 (step S15).

The calculation processing unit 42 calculates the magnitude |Z| of the impedance Z between the overhead lines 2 at the second frequency from the relationship between the test AC voltage Vt and the AC current It. (Step S16)

Once the magnitude |Z| of impedance Z at two frequencies has been determined, the state between the selected overhead lines 2 can be determined by comparing the magnitude |Z| of impedance Z at the high frequency with the magnitude |Z| of impedance Z at the low frequency. In other words, if the magnitude |Z| of impedance Z at the high frequency is smaller than the magnitude |Z| of impedance Z at the low frequency, it can be determined that the overhead lines are in a separated state with no short circuit (step S17).

If there is a short circuit between the overhead lines 2, a warning can be displayed on the warning generating unit 26, and at the same time, a warning sound such as a buzzer can be generated to generate a warning (step S18).

Next, it is confirmed whether the status check between all the overhead lines 2 has been completed (step S19). If there are any overhead lines 2 for which the status check has not been completed, the process returns to step S10, the switch unit 22 is switched to the overhead lines 2 for which the short-circuit check has not been performed, and the processes of steps S10 to S19 are repeated. If the status check between all the overhead lines 2 has been completed, the process proceeds to the next step S20.

When the status check between all the overhead lines 2 is completed, the operator is informed of the inspection result by lighting up the green LED and sounding a short buzzer to indicate that the entire sequence for checking for short circuits has been completed (step S20).

By practicing the line short circuit confirmation method using the line short circuit confirmation device 40 configured as described above, the state of the overhead lines can be confirmed by comparing the magnitude |Z| of the impedance Z between the overhead lines 2, so that the short circuit state and the separation state can be confirmed more reliably. This makes it possible to start feeding electricity to the overhead line 2 after construction with peace of mind.

Claims (4)

A line short circuit confirmation device that is a device for checking the overhead line state of an AT feeding circuit of an AC electric railway, and is characterized by comprising: an AC voltage generation unit that generates an inspection AC voltage of at least one frequency between 200 Hz and 1 kHz; a switch unit that sequentially applies the inspection AC voltage generated by the AC voltage generation unit between two overhead lines of the feeding wire, the contact wire, and the protective wire that make up the AT feeding circuit; a current measurement unit that measures the AC current that flows between the overhead lines when the inspection AC voltage is applied between the overhead lines; a calculation processing unit that calculates the reactance between the overhead lines from the relationship between the inspection AC voltage and the AC current; and an overhead line state confirmation unit that confirms that the overhead lines are separated and not shorted because the reactance has a capacitive characteristic. A line short circuit confirmation device that is a device for checking the overhead line state of an AT feeding circuit of an AC electric railway, and is characterized by comprising an AC voltage generation unit that generates an inspection AC voltage of at least one frequency between 200 Hz and 1 kHz, a switch unit that sequentially applies the inspection AC voltage generated by the AC voltage generation unit between two overhead lines of the feeding wire, the contact wire, and the protective wire that make up the AT feeding circuit, a current measurement unit that measures the AC current that flows between the overhead lines when the inspection AC voltage is applied between the overhead lines, a calculation processing unit that calculates the phase angle of the inspection AC voltage with respect to the AC current, and an overhead line state confirmation unit that confirms that the overhead lines are in a separated state and not short-circuited because this phase angle is a delayed angle. a switch unit that sequentially applies the inspection AC voltages generated by the AC voltage generating unit between two of the power feeder wire, the contact wire, and the protective wire that constitute the AT feeding circuit; a current measuring unit that measures the AC current that flows between the overhead wires when the inspection AC voltages of the two frequencies are applied between the overhead wires; a calculation processing unit that calculates the magnitude of impedance between the overhead wires at both frequencies from the relationship between the inspection AC voltage and the AC current; and an overhead wire state checking unit that checks whether the overhead wires are in a separated state and not short-circuited, based on the fact that the magnitude of impedance at the higher of the two frequencies is smaller than the magnitude of impedance at the lower of the two frequencies . A method for checking whether the state of the overhead wires at the location of the AT feeding circuit of an AC electric railway after its re-laying work is sound before the start of feeding, the method comprising the steps of: generating an inspection AC voltage of at least one frequency between 200 Hz and 1 kHz; sequentially applying this inspection AC voltage between the grounding terminals of the grounding wires used for the re-laying work of two overhead wires out of the feeder wire, contact wire, and protective wire that make up the AT feeding circuit; measuring the AC current flowing between the overhead wires; determining the impedance between the overhead wires from the relationship between the inspection AC voltage and the AC current; and confirming that the overhead wires are in a separated state and not short-circuited when this impedance is within a range that indicates a separated state.

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