JP2011053189A - Ground fault detection device for dc electric railway - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly detect a grounding fault constantly with the same sensitivity at both substations when the grounding fault occurs. <P>SOLUTION: A ground fault detection device for a DC electric railway includes voltage measuring parts 18 and 28 for respective substations which measure voltage between a rail 4 of a feeding system of the DC electric railway and grounds 15 and 25 of a plurality of substations 1 and 2 connected to the feeding system, a dedicated communication line 6 for mutually transmitting the measured voltage to the adjacent substations 2 and 1, and sensitivity compensation calculation processing parts 19 and 29 for the respective substations for summing up voltage measured by the own voltage measuring part of the substation with the voltage measured by the voltage measuring part of the adjacent substation and sent through the dedicated communication line 6 to determine the sum as ground fault detecting voltage σ V and for output of a protective signal when the ground fault detecting voltage σ V exceeds a predetermined set value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a ground fault detection device for a DC electric railway that detects a ground fault occurring inside and outside adjacent substations connected to a feeding system of the DC electric railway.

  Substations 1 and 2 are connected to the feeding system of the DC electric railway as shown in FIG. Each of the substations 1 and 2 is generally connected to both ends of the feeder line 3 in one section and supplies DC power.

  The substation 1 includes an AC power supply 11, an AC circuit breaker 12, a rectifier circuit 13, a feeder circuit breaker 14, and the like. The AC power supplied from the AC power supply 11 is converted into required DC power by the rectifier circuit 13, It is supplied to one end side of the feeder 3 through the feeder circuit breaker 14.

  The other substation 2 has the same configuration as that of the substation 1, and the DC power converted by the rectifier circuit 23 is supplied to the other end of the feeder 3 through the feeder circuit breaker 24.

  As a means for detecting a DC ground fault at each of the substations 1 and 2 of the DC electric railway, ground fault detection devices 16 and 26 are provided between the rail 4 of the feeder system and the substation mesh grounds 15 and 25. 3, the local fault detectors 16 and 26 sense the potential increase of the substation mesh grounds 15 and 25, and the feeder circuit breakers 14 and 24 on the substations 1 and 2 side are respectively connected. Open and protect the feeder 3 and the like.

  By the way, when a ground fault occurs in the feeder 3, a ground fault occurs at one of the substations, for example, one ground fault detection device 16 side, according to the distance between the ground fault position and the ground fault detection devices 16 and 26. May be detected, but the ground fault detection device 26 may not be able to detect a ground fault. Of course, the reverse is also possible. This is because the detection sensitivity varies depending on the distance from the ground fault detection devices 16 and 26 to the ground fault position. As a result, it becomes difficult to protect the components of the substations 1 and 2 including the feeder 10.

  Therefore, a ground fault has been detected by connecting a communication device already installed in each substation 1 and 2 as the communication disconnection devices 17 and 27 and connecting the communication disconnection devices 17 and 27 with the communication line 5. The side ground fault detection device 16, for example, opens the feeder circuit breaker 14 of the own substation 1, and further sends a disconnection command signal to the contact disconnection device 27 of the adjacent substation 2 via the communication disconnection device 17. The electric circuit breaker 24 is opened to take measures to avoid the influence of the ground fault accident (Patent Document 1).

JP 2002-040087 A

  However, according to the technique described in Patent Document 1, the communication disconnecting devices 17 and 27 of both substations 1 and 2 are originally installed to exchange various information between the substations 1 and 2. The information includes a shut-off command signal in the event of a ground fault and exchanges information with each other.

  As a result, if a ground fault occurs while transferring other purpose information using the communication line 5, the situation of the ground fault will be notified after completion of the other information transfer, There is a problem that protection of the components of the substations 1 and 2 including the feeder 10 is delayed.

  Further, since the conventional DC ground fault detection means has variations in detection sensitivity depending on the ground fault position as described above, it cannot detect a ground fault at the same speed and at a high speed.

  The present invention has been made in view of the above circumstances. When a ground fault occurs, the ground fault is always detected at a high speed with the same sensitivity at a substation connected to both ends of the feeder line. An object of the present invention is to provide a ground fault detection device for a DC electric railway that protects substation equipment including a grid.

  In order to solve the above problems, a ground fault detection device for a DC electric railway according to the present invention is a protection device installed at a plurality of substations connected to a feeding system of the DC electric railway, A voltage measuring means for each substation that measures the voltage between the rails of the system and the ground of each substation, a dedicated communication line that transmits the voltage measured by each voltage measuring means to the adjacent substations, and The voltage measured by the voltage measuring means of the own substation and the voltage measured by the voltage measuring means of the adjacent substation and sent through the dedicated communication line are added as a ground fault detection voltage, and this ground fault detection And a sensitivity compensation calculation processing unit for each substation that outputs a protection signal when the working voltage exceeds a predetermined set value.

  The ground fault detection apparatus for a DC electric railway according to the present invention includes a voltage measuring unit for each substation that measures a voltage between a rail of the feeder system and the ground of each substation, and each voltage measuring unit. A dedicated communication line that transmits the measured voltage to the adjacent substation, a voltage measured by the voltage measuring means of the own substation, and a voltage measured by the voltage measuring means of the adjacent substation and sent through the dedicated communication line Is multiplied by an amplification coefficient obtained by subtracting the ratio of the subtraction amount of the voltage value measured by the voltage measuring means from the value of the required multiple of the added voltage. After obtaining the fault detection voltage, when the ground fault detection voltage exceeds a predetermined set value, a sensitivity compensation calculation processing unit for each substation that outputs a protection signal is provided.

  According to the present invention, when a ground fault occurs, it is always possible to detect a ground fault at a high speed with the same sensitivity at a substation connected to both ends of the feeder line. It is possible to provide a ground fault detection device for a DC electric railway that reliably protects.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows Embodiment 1, 2 of the ground-fault detection apparatus of the DC electric railway which concerns on this invention. The electrical system diagram at the time of the ground fault of the feeding system of a DC electric railway, and the simple equivalent circuit diagram of the said electrical system. The figure showing the relationship between the ratio of a ground fault point and voltage V1, V2 measured at each adjacent substation, and the assumed value of the component of the equivalent circuit in that case. Ground fault detection voltage σV ′ obtained by calculation from the ratio of ground fault points and voltage V1, V2 measured at each adjacent substation, explaining the second embodiment of the ground fault detection device for DC electric railway according to the present invention. The figure showing the assumption of the component of an equivalent circuit in that case, and the equivalent circuit in that case. The block diagram which shows the ground fault detection apparatus of the conventional DC electric railway.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram showing Embodiment 1 of a ground fault detection apparatus for a DC electric railway according to the present invention. In the figure, the same parts as those in FIG.

  In the feeding system of the DC electric railway, the substations 1 and 2 are connected to both ends of the feeder 3 in one section, respectively, and the required DC power is supplied to the feeder 3 from each of the substations 1 and 2. The

  Each of the substations 1 and 2 has substantially the same configuration as that in FIG. That is, the substation 1 includes an AC power source 11, an AC circuit breaker 12, a rectifier circuit 13, a feeder circuit breaker 14, and the like, and converts AC power supplied from the AC power source 11 into required DC power by the rectifier circuit 13. Then, it is supplied to one end side of the feeder 3 through the feeder circuit breaker 14.

  The other substation 2 is also configured by an AC power source 21, an AC circuit breaker 22, a rectifier circuit 23, a feeder circuit breaker 24, and the like. The AC power supplied from the AC power source 21 is converted into required DC power by the rectifier circuit 23. It is converted and supplied to the other end side of the feeder 3 through the feeder circuit breaker 24.

  Further, the substation 1 is provided between the rail 4 on the substation 1 side and the substation mesh ground 15, and measures a voltage generated between the rail 4 and the ground 15. A sensitivity compensation calculation processing unit 19 is provided that performs a protection process when an accident is detected.

  The sensitivity compensation calculation processing unit 19 includes a communication unit 19A having a transmission / reception function, a storage unit 19B that stores voltage values 18a and 28a measured at the substations 1 and 2, and a voltage measurement unit 18 at the time of a ground fault. The measured voltage 18a (V1) and the voltage 28a (V2) transmitted from the adjacent substation 2 side are stored in the storage unit 19B, and addition operation is performed to obtain a ground fault detection voltage with the same sensitivity. After that, when a predetermined set value is exceeded, a sensitivity compensation calculation unit 19C that determines a ground fault is output, and when a determination result of a ground fault is received, a cutoff signal 19a is output and the feeder circuit breaker 14 is opened. And an operation output unit 19D.

  Furthermore, on the substation 2 side, a voltage measuring unit 28 that measures a voltage generated between the rail 4 and the substation mesh ground 25, and a sensitivity compensation calculation processing unit 29 that executes a protection process when a ground fault is detected, As with the sensitivity compensation calculation processing unit 19, the sensitivity compensation calculation processing unit 29 includes a communication unit 29A, a storage unit 29B that stores voltages 28a (V2) and 18a (V1), and a sensitivity compensation calculation unit 29C. , The operation output unit 29D, and the communication units 19A and 29A of the sensitivity compensation calculation processing units 19 and 29 are connected by a dedicated communication line 6 by wire.

  The sensitivity compensation calculation unit 29C of the compensation calculation processing unit 29 on the substation 2 side is transmitted via the dedicated communication line 6 from the substation 1 side adjacent to the voltage 28a measured by the voltage measurement unit 28 at the time of the ground fault. The incoming voltage 18a is stored in the storage unit 29B, and after addition calculation is performed to obtain a ground fault detection voltage with the same sensitivity, when a predetermined set value is exceeded, a ground fault is determined, and the determination result Is sent to the operation output unit 29D. The operation output unit 29D outputs a cut-off signal 29a and opens the feeder breaker 24.

  Next, prior to the sensitivity compensation computation processing of the sensitivity compensation computation processing units 19 and 29, the ratio of the length of the feeder 3 from the conventional ground fault detection devices 16 and 26 to the ground fault point and the ground fault detection voltage The relationship will be described.

  When a ground fault occurs in the feeder 3, the fault detection of the local fault detectors 16 and 26 is performed according to the ratio of the length to the total length of the feeder 3 from the ground fault detectors 16 and 26 to the ground fault point. The voltage is different. That is, the voltage detection sensitivity at the time of the ground fault differs for each of the substations 1 and 2. This means that when a fixed set value is previously set in each of the ground fault detection devices 16 and 26, the ground fault detection devices 16 and 26 far from the ground fault point cannot detect the ground fault.

  Therefore, in order to detect a ground fault with the same detection sensitivity without being affected by the ratio of the length to the total length of the feeder 3 up to the ground fault point, the voltage detected at each substation 1, 2 side is used. If they are received and added to each other and used as a ground fault detection voltage when a ground fault is detected, the ground fault can be detected stably and at high speed.

  Next, with reference to FIG. 2, a processing example in which each substation 1 and 2 has the same detection sensitivity will be described in consideration of the ratio of the length of the feeder 3 to the ground fault point. FIG. 2 is a simple equivalent circuit when a ground fault occurs in the feeder 3.

  2, when a ground fault 31 occurs in the feeder 3, the fault current I1 of the substation 1, the voltage V1 between the rail 4 and the mesh ground 15, the fault current I2 of the substation 2, Assuming the voltage V2 between the rail 4 and the mesh ground 25, it is considered that almost all of the fault currents I1 and I2 due to the ground fault return to the ground fault point via the rail 4.

As a result, the addition voltage (ground fault detection voltage voltage) σV between the rails 4 of the substations 1 and 2 and the mesh grounds 15 and 25 can be expressed by Expression (1).
σV = V1 + V2 = (I1 + I2) · R _R (1)
Here, the rail resistance R _R can be approximated by a constant value that does not depend on the fault point since the fault currents I1 and I2 almost return to the ground fault point via the rail 4 as described above. it can.

  However, the combined resistance of the entire equivalent circuit changes according to the resistance ratio from the ground fault point of the feeder 3, and accordingly the fault currents I1 and I2 on the substations 1 and 2 side also differ. Based on the equivalent circuit, the combined resistance σR and the fault currents I1 and I2 are solved.

When the internal resistance of the rectifier circuits 13 and 23 of the substations 1 and 2 is R _SR and the feeder resistance is R _F from the lower equivalent circuit in FIG. 2, the combined resistance σR is expressed by the following equation (2).

σR = {(R _SR + dR _F ) (R _SR + (1-d) R _F )} / {2R _SR + dR _F + (1-d) R _F )}
(2)
Here, the ratio d of the resistance R _F from the ground fault point of the feeder 3 can be said to be the ratio d of the ground fault point when the feeder section is “1”.

Therefore, when the fault currents I1 and I2 of the substations 1 and 2 are obtained using the combined resistance σR obtained by the expression (2), they can be expressed by the expressions (3) and (4).
I1 = {1500 / (R _R + Re + σR)} · {(R _SR + (1−d) R _F ) / (2R _SR + dR _F )}
...... (3)
I2 = {1500 / (R _R + Re + σR)} · {(R _SR + dR _F ) / (2R _SR + dR _F )}
...... (4)
Accordingly, the fault currents I1 and I2 of the substations 1 and 2 are obtained based on the equations (3) and (4) while taking into account the ratio d of the ground fault points, and then each substation according to the equation (1). When the detection voltages V1 and V2 between the rail 4 at the stations 1 and 2 and the mesh grounds 16 and 26 are obtained, the detection is completely contradictory according to the change in the ratio d of the ground fault points as shown in FIG. This is a graph of the characteristics of the voltages V1 and V2. However, FIG. 3A shows an example applied to a 1500V DC electric railway.

  Therefore, in the sensitivity compensation calculation processing unit 19, the voltage 18a (V1) measured by the voltage measurement unit 18 of the own substation 1 and the other voltage measurement unit 28 are measured, and from the sensitivity compensation calculation processing unit 29 to the dedicated communication line 6 Is added to the voltage 29a (V2) sent via the, and as shown in FIG. 3A, a substantially constant high ground fault detection voltage σV is obtained without being influenced by the ratio d of the ground fault points. Obtainable.

  The sensitivity compensation calculation processing unit 29 can also obtain the ground fault detection voltage σV exactly the same as in FIG.

  Accordingly, each of the sensitivity compensation calculation processing units 19 and 29 considers a change in an assumed value of a component of the equivalent circuit as shown in FIG. 3B, and uses a ground fault detection voltage σV obtained by adding in advance. If a low predetermined set value (for example, (A) in the figure) is set, the ground fault detection voltage σV at which both substations 1 and 2 have almost the same detection sensitivity are compared with the set value to detect the ground fault. When the working voltage σV exceeds the set value, the interruption signals 19a and 29a are output, respectively, and the feeder circuit breakers 14 and 24 on the substations 1 and 2 side can be opened.

  Therefore, in the embodiment as described above, since the ground fault detection voltage becomes lower as the distance from the substations 1 and 2 to the ground fault point becomes longer, conventionally, at the far end from the substation. The generated ground fault accident cannot be detected, and the detection of the ground fault accident becomes very unstable.

  As a result, in the past, the self-current breaker was opened on the condition that the ground fault detection voltage exceeded a fixed set value, and the self-contact breaker was used to install it at an adjacent substation. Since it is necessary to notify the communication interruption device that there is a ground fault, and the notification is made after waiting for the end of the information for other purposes, the time is delayed.

  In that respect, the present invention immediately transmits the detected voltage measured by the voltage measuring units 18 and 28 to the sensitivity compensation calculation processing units 29 and 19 of the adjacent substations via the communication units 19A and 29A and the dedicated communication line 6. Since the detection voltages measured by the voltage measuring units 18 and 28 are added and calculated, the ground fault detection voltage is obtained and compared with the set value, the sensitivity compensation calculation processing units 19 and 29 are stable with the same detection sensitivity. And a ground fault can be detected at high speed, and the components of the substations 1 and 2 including the feeder 3 can be protected.

  By the way, in the case of voltage addition according to the equation (1), as shown in FIG. 3 (a), the added voltage value becomes lower as the ground fault point becomes near the middle of both substations 1 and 2. Therefore, as a setting value, for example, if a low value is set in advance assuming that a ground fault will occur between the two substations 1 and 2, the detection sensitivity of the ground fault will be the ground fault point. Therefore, both substations 1 and 2 can detect a ground fault with the same detection sensitivity, and can achieve protection at a high speed by using the same detection sensitivity.

(Embodiment 2)
Since the second embodiment of the ground fault detection apparatus for a DC electric railway according to the present invention has the same configuration as that shown in FIG. 1, it will be described here with reference to FIG.

  In particular, the second embodiment differs from the second embodiment in that the voltage for ground fault detection of the sensitivity compensation calculation processing sections 19 and 29 is improved.

  The sensitivity compensation calculation processing units 19 and 29 in the first embodiment use the added voltage value obtained by simply adding the voltages 18a and 28a measured by the voltage measuring units 18 and 28 of both substations 1 and 2 as a ground fault detection voltage. As a result, the detection sensitivity of the ground fault detected by the feeder 3 can be the same detection sensitivity for both the substations 1 and 2 regardless of the ground fault point.

  However, when the voltages 18a and 28a measured by the voltage measuring units 18 and 28 are simply added as described above and used as a ground fault detection voltage, as shown in FIG. When a ground fault occurs near the middle, the distance from the ground fault point becomes longer and the ground fault detection voltage becomes lower. For example, if the fluctuations in the assumed values of the components of the equivalent circuit are considered, the drop in the added voltage value may be further increased. As a result, depending on the determined setting value, the detection of a ground fault may become unstable.

  Therefore, in the second embodiment, a ground fault occurs near the middle of both substations 1 and 2 by multiplying the addition voltage value (V1 + V2) obtained in the first embodiment by a predetermined amplification coefficient. In addition, the ground fault detection voltage σV ′ is obtained by using the addition calculation formula (5) that can obtain the highest predetermined voltage.

σV ′ = (V1 + V2) · [2-{(| V1-V2 |) / (| V1 + V2 |)}]
...... (5)
That is, the ground fault detection voltage σV ′ is a value of a required multiple of the added voltage value (V1 + V2) with respect to the added voltage value σV ′ (= V1 + V2) measured at both substations (for example, 1.5 to 2.0) is obtained by multiplying the amplification factor obtained by subtracting the ratio (| V1-V2 |) / (| V1 + V2 |) of the subtraction amount of the voltage value measured at both substations 1 and 2. Is.

  FIG. 4A is a graph showing a change in the ground fault detection voltage σV ′ with respect to the ratio d of the local fault points determined by the calculation formula of the above formula (5). However, this graph is an example in which the required multiple value is set to “2”.

  Unlike the graph of the ground fault detection voltage σV of the first embodiment, the graph of the ground fault detection voltage σV ′ can increase the voltage value at the time of the ground fault near the middle of the two substations 1 and 2. Therefore, for example, from the addition voltage obtained by adding and calculating the measurement voltages V1 and V2 obtained at the ground fault point of the ground fault point of the first embodiment with the minimum ratio d = 0.0 and the maximum ratio 1.0. If a lower neighborhood value (for example, (b) in the figure) is set, the ground fault can be detected stably and with high sensitivity.

(Other embodiments)
(1) In the above embodiment, a communication device for exchanging information between the substations 1 and 2 is omitted, but a communication device is provided in each substation 1 and 2 as in the prior art, It may be configured to exchange information with each other.

(2) The communication units 19A and 29A of the sensitivity compensation calculation processing units 19 and 29 transmit the measured voltages 18a and 28a on the own substation side to the adjacent counterpart communication units 29A and 19A. 19A and 29A communicate with each other using a communication protocol that receives a reception response result, so that the reliability of protection against a ground fault can be improved.

(3) In the above-described embodiment, the example using the mesh grounds 15 and 25 has been described, but it is needless to say that the mesh ground is not necessarily required.

In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  1, 2 ... substation, 3 ... feeder, 4 ... rail, 6 ... dedicated communication line, 11, 21 ... alternating current power supply, 13, 23 ... rectifier circuit, 14, 24 ... feeder breaker, 18, 28 ... voltage Measurement unit 19, 29 ... Sensitivity compensation calculation processing unit, 19A, 29A ... Communication unit, 19B, 29B ... Storage unit, 19C, 29C ... Sensitivity compensation calculation unit, 19D, 29D ... Operation output unit.

Claims (5)

A protection device installed in a plurality of substations connected to a feeding system of a DC electric railway,
Voltage measuring means for each substation for measuring the voltage between the rails of the feeder system and the ground of each substation;
A dedicated communication line that transmits the voltage measured by each voltage measurement means to the adjacent substations;
The voltage measured by the voltage measuring means of the own substation and the voltage measured by the voltage measuring means of the adjacent substation and sent through the dedicated communication line are added as a ground fault detection voltage, and the ground fault detection A ground fault detection device for a DC electric railway, comprising: a sensitivity compensation calculation processing unit for each substation that outputs a protection signal when a working voltage exceeds a predetermined set value. In the ground fault detection apparatus of the DC electric railway according to claim 1,
The sensitivity compensation calculation processing unit includes a communication unit having a transmission / reception function connected to the dedicated communication line, a storage unit that stores a voltage measured by the voltage measurement unit, and a voltage measurement unit of the substation. The measured voltage and the voltage sent through the dedicated communication line from the adjacent substation side are stored in the storage unit, and the ground fault detection voltage is obtained by addition calculation. When the voltage exceeds the predetermined set value, a sensitivity compensation calculation unit for determining a ground fault, and when receiving a determination result of a ground fault from the sensitivity compensation calculation unit, a protection signal is output, A ground fault detection device for a DC electric railway, characterized by comprising an operation output unit for opening a feeding circuit breaker on the site side. In the ground fault detection apparatus of the DC electric railway according to claim 1,
As for the set value, the ground fault detection voltage obtained by adding the voltage measured by the both voltage measuring means to the ground fault near the middle of the feeders connected to the two substations is the most. A ground fault detection device for a DC electric railway characterized in that a predetermined set value lower than the lowest voltage is set in consideration of lowering. A protection device installed in a plurality of substations connected to a feeding system of a DC electric railway,
Voltage measuring means for each substation for measuring the voltage between the rails of the feeder system and the ground of each substation;
A dedicated communication line that transmits the voltage measured by each voltage measurement means to the adjacent substations;
For an added voltage obtained by adding the voltage measured by the voltage measuring means of the own substation and the voltage measured by the voltage measuring means of the adjacent substation and sent through the dedicated communication line, a predetermined value of the added voltage is determined. After multiplying the amplification factor obtained by subtracting the ratio of the subtraction amount of the voltage value measured by the voltage measuring means from the multiple value to obtain the ground fault detection voltage, the ground fault detection voltage is A ground fault detection device for a DC electric railway, comprising: a sensitivity compensation calculation processing unit for each substation that outputs a protection signal when a predetermined set value is exceeded. In the ground fault detection apparatus of the DC electric railway according to claim 4,
The set value is a neighborhood value lower than the added voltage obtained by adding and calculating the voltage at the ground fault point at which the resistance ratio of the feeders measured at the voltage measuring means of both substations is minimum and maximum. A ground fault detection device for a DC electric railway characterized by being set.

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