JP2023035317A - Dc high voltage ground relay - Google Patents

Abstract

To provide an erroneous detection prevention type DC voltage ground relay having a high reliability so as to prevent train operations from being affected without malfunction due to ground faults on a secondary side line of high-voltage distribution transformers installed in DC substations for electric railways, and so on.SOLUTION: A DC high voltage ground relay includes: a potential difference measurement unit 5 that is provided between a ground mat 3 and a return line 4 of a DC substation 2 for an electric railway and measures the potential difference; a DC ground fault determination output unit 6 that determines a DC ground fault using the potential difference and outputs a DC ground fault signal Fd; and a malfunction prevention unit 13 that prevents the DC ground fault determination output unit 6 from outputting the determination of the DC ground fault signal Fd when the potential difference occurred between the ground mat 3 and the return line 4 is due to a ground fault in an AC electric circuit 2A.SELECTED DRAWING: Figure 1

Description

The present invention relates to a DC high-voltage earthing relay, and more specifically, it malfunctions when a ground fault occurs in an AC high-voltage distribution line other than a DC bus line of an electric railway installed in a DC substation for electric railways. It relates to a DC high voltage grounding relay with high reliability without

Conventionally, in DC substations for electric railways, when a serious fault such as a ground fault occurs in a DC bus, a large amount of ground fault current flows, causing failures such as burning of substation equipment. Therefore, the potential difference between the grounding mat and the return line (rail) of the DC substation for electric railways is detected, and when this potential difference exceeds a predetermined level, the substation is shut down as soon as possible. DC high voltage grounding relays are installed to limit damage to station equipment and protect substations.

FIG. 14 is a diagram showing the configuration of a DC substation for electric railways to which a conventional DC high-voltage earthing relay 90 is installed. As shown in FIG. 14, in a DC substation for electric railways, power is branched from a busbar of an extra-high voltage distribution line and supplied to facilities such as traffic lights, lighting, escalators, and ticket vending machines via transformers Ta for high-voltage distribution lines. A high-voltage distribution line 91A to which the power is supplied, and a DC distribution line (DC bus) 91B, which is DC-converted by the rectifier B via the rectifier transformer Tb and supplied to the feeder line, is supplied with power.

FIG. 15 is a diagram showing the configuration of a conventional DC high-voltage grounding relay represented by Patent Document 1. In FIG. A DC high voltage grounding relay 90 shown in FIG. 15 is installed between a grounding mat 92 and a return line 93 (rail R) of a substation and has a potential difference measuring section 94A for measuring the potential difference therebetween. detects a potential difference equal to or greater than the threshold, the ground fault determination output unit 94B determines a DC ground fault, and outputs a cutoff signal (DC ground fault signal) to the AC circuit breaker 90A (see FIG. 14) and the DC high-speed circuit breaker 90B. is sent and the power supply to the feeder line 95 and the DC bus 91B is interrupted.

When a ground fault occurs in the DC bus 91B, the potential of the ground mat 92 becomes higher than that of the return wire 93 due to the effect of the ground fault. Fault detection can be done within a very short operating time of the order of 40 ms. Therefore, by breaking the AC circuit breaker 90A and the DC high-speed circuit breaker 90B as soon as possible, damage to the equipment can be minimized.

JP 2010-42784 A

However, when a ground fault occurs in the secondary line (high voltage distribution line 91A) of the high voltage distribution transformer Ta of the conventional DC substation for electric railways, a high AC voltage is applied to the grounding mat 92, , the DC high-voltage grounding relay 90 may erroneously detect an AC ground fault.

That is, in general, the AC ground fault of the secondary side line (high voltage distribution line 91A) of the high voltage distribution transformer Ta is prevented by the AC circuit breaker 96, 96A ~ Although it should be cut off and protected by 96C, when a ground fault occurs in the high-voltage distribution line 91A of the electric railway DC substation, the potential of the grounding mat 92 of the substation fluctuates due to the ground fault voltage. Therefore, a relatively large potential difference is generated between the ground mat 92 and the return line 93 connected to the rail R at a location remote from the ground mat 92 .

FIG. 16 is a diagram showing an AC voltage waveform of a 50 Hz, 6600 V system. More specifically, with reference to FIG. 16, when a ground fault occurs in the high-voltage distribution line 91A, depending on the ground fault situation, assume that the full voltage is applied between the ground mat and the return line (rail). For example, an AC half-wave voltage is applied to the potential difference measuring section 94A of the DC high-voltage grounding relay 90 having a set value of 500V.

Therefore, due to the potential difference (AC voltage), a half-wave AC voltage on the circuit is applied to the potential difference measuring section 94A of the DC high voltage grounding relay 90. For example, a DC voltage equivalent to a set threshold value of 500 V or more is applied for about 9.7 ms. It will be applied continuously. Therefore, when the ground fault voltage is high, the DC high-voltage grounding relay 90 malfunctions, and the AC circuit breaker 90A and the DC high-speed circuit breaker 90B of the substation are erroneously cut off, thereby stopping the power supply to the train. There was a problem with what happened.

In this way, when an AC ground fault occurs on the high voltage distribution line 91A side and the DC high voltage grounding relay 90 malfunctions, the state of the substation will be a total blackout state due to its function. It takes a lot of time, and there was a problem that it caused a big obstacle to the operation of the train.

Through years of intensive research, the applicant has found that the conventional DC high-voltage grounding relay 90 installed in a DC substation for electric railways is replaced by a secondary side line of a high-voltage distribution transformer Ta installed in the same substation. We pursued the cause of the malfunction due to the ground fault and found out that the above-mentioned phenomenon is related to this malfunction.

Therefore, it is easily conceivable to intentionally slow down the reaction speed of the ground fault judgment output section 94B to prevent the occurrence of malfunction. That is, when an AC ground fault occurs on the high voltage distribution line 91A side, the AC ground fault is detected on the high voltage distribution line 91A side, and the high voltage distribution line transformer Ta is cut off in about 100 ms. The effect of an AC ground fault is reduced. Therefore, the response speed of the ground fault determination output section 94B is intentionally slowed, and the ground fault determination output section 94B is activated only when a potential difference of 400 to 600 V or more, which is the set value, can be confirmed over a time period of about 100 ms. It is conceivable to prevent malfunction by detecting a ground fault in the DC distribution line 91B and sending a disconnection signal to the AC circuit breaker 90A and the DC high-speed circuit breaker 90B to cut off the power supply to the DC bus 91B. .

However, in this case, although the malfunction of the DC high-speed circuit breaker 90B can be avoided, even if a DC ground fault occurs in the DC power distribution path 91B, it will take at least 100 ms or more from the occurrence of the effect of the ground fault current. Therefore, if a large fault current continues to flow for 100 ms or more, there is a problem that the possibility of damage such as damage to the facility increases remarkably.

The present invention has been made in consideration of the above-mentioned matters, and its object is to prevent malfunction due to a ground fault or the like in the secondary line of a high-voltage distribution transformer installed in a DC substation for electric railways. Disclosed is a high-reliability erroneous detection prevention type DC high-voltage grounding relay capable of interrupting a fault current as quickly as possible when a ground fault occurs in a DC power distribution path. That's what it is.

A first invention comprises a potential difference measuring unit provided between a grounding mat and a return line of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. a direct current ground fault determination output unit for outputting; an auxiliary power supply unit charged using the rail potential generated between the grounding mat and the return line; and the potential difference measurement unit using the electric power charged in the auxiliary power supply unit. and an AC ground fault that determines an AC ground fault when the commercial frequency component computed by the fast Fourier transform unit exceeds a threshold value for determining a ground fault in the AC circuit. An erroneous detection prevention device comprising: a judging section; and a malfunction prevention section for blocking judgment output of a DC ground fault by the DC ground fault judgment output section when the AC ground fault judging section judges an AC ground fault. provide a type DC high voltage earthing relay. (Claim 1)

The ground mat is grounded to the ground potential of the substation via grounding resistors, whereas the potential of the return line connected to the rail at a remote location with respect to this ground mat is above it. Since current flows through the running train, some rail potential is generated between the grounding mat and the return line, and the auxiliary power supply section is charged using this rail potential. Always charged. The auxiliary power supply unit may be a secondary battery that can be charged and discharged, but it is preferable to use a capacitor with a simpler configuration. More preferably, an electric double layer capacitor is used to increase the capacity.

The electric power charged in the auxiliary power supply is used by the fast Fourier transform unit to perform a fast Fourier transform operation on the potential difference measured by the potential difference measuring unit. An FFT circuit for obtaining frequency components is conceivable, but it may also be, for example, an arithmetic processing unit and a fast Fourier transform program that can be executed by this arithmetic processing unit. Moreover, the frequency component obtained by the fast Fourier transform is at least the commercial frequency component (the frequency component of the commercial power supply), which is 60 Hz in the Kansai region of Japan and 50 Hz in the Kanto region of Japan. The output of this fast Fourier transform unit is accurate enough to reliably detect a ground fault in an AC power supply based on the calculation result for one wavelength of commercial frequency (16.7 ms for Kansai and 20 ms for Kanto). can be obtained.

The AC ground fault determination unit determines an AC ground fault when the commercial frequency component frequency-analyzed by fast Fourier transform operation exceeds a threshold value for determining a ground fault in the AC electric circuit. It is possible to reliably determine an AC ground fault within a short time of about 16.7 to 20 ms from the time of occurrence. This ground fault determination unit is also realized by an AC ground fault determination program that can be executed by the same arithmetic processing unit as the fast Fourier transform unit, thereby simplifying the configuration and reducing the manufacturing cost. It goes without saying that this is possible.

The malfunction prevention unit prevents the DC ground fault determination output unit from outputting a determination of a DC ground fault from the time when the AC ground fault determination unit determines an AC ground fault. A switch section that does not output a DC ground fault signal while judging an AC ground fault, or a switch section that does not input a potential difference signal to the DC ground fault judgment output section while judging an AC ground fault can be considered. .

Therefore, when a ground fault occurs in the high-voltage distribution line of a substation, the AC ground fault determination unit quickly and reliably determines the ground fault by making full use of the fast Fourier transform, and the malfunction prevention unit detects the DC ground fault. Since malfunction of the discrimination output unit can be prevented, malfunction of the DC high-voltage grounding relay due to ground fault in the high-voltage distribution line in the substation is eliminated, and reliability is improved accordingly.

A second invention comprises a potential difference measuring unit provided between a grounding mat and a return wire of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. A DC ground fault detection output unit that outputs output, a current measurement unit that measures the current flowing in the electric circuit between the grounding mat and the return line, and an auxiliary that is charged using the rail potential generated between the grounding mat and the return line a power supply unit, a fast Fourier transform unit that performs a fast Fourier transform operation on the output of the current measurement unit using the power charged in the auxiliary power supply unit, and a commercial frequency component calculated by the fast Fourier transform unit for the AC electric line. an AC ground fault determination unit that determines an AC ground fault when a threshold value for determining a ground fault is exceeded; and a DC ground fault by the DC ground fault determination output unit when the AC ground fault is determined by the AC ground fault determination unit. There is provided an erroneous detection prevention type DC high voltage grounding relay characterized by comprising a malfunction prevention part for blocking the judgment output of. (Claim 2)

The current measuring unit measures the current flowing in the electric circuit between the grounding mat and the return wire. , the magnitude of the current on the secondary side is preferably converted into a measurable magnitude for measurement. That is, when there is a change in the current flowing through the primary side of the current transformer, the change in the magnetic flux density excited by this causes a current of a magnitude divided by the turns ratio to flow in the secondary side, causing an AC ground fault. occurs, a secondary current proportional to the magnitude of the AC ground fault flows and can be measured.

The ground mat is grounded to the ground potential of the substation via grounding resistors, whereas the potential of the return line connected to the rail at a remote location with respect to this ground mat is above it. Since current flows through the running train, some rail potential is generated between the grounding mat and the return line, and the auxiliary power supply section is charged using this rail potential. Always charged. The auxiliary power supply unit may be a secondary battery that can be charged and discharged, but it is preferable to use a capacitor with a simpler configuration. More preferably, an electric double layer capacitor is used to increase the capacity.

The power charged in the auxiliary power supply section is used by the fast Fourier transform section to perform fast Fourier transform calculations on the current measured by the current measuring section. An FFT circuit for obtaining frequency components is conceivable, but it may also be, for example, an arithmetic processing unit and a fast Fourier transform program that can be executed by this arithmetic processing unit. Moreover, the frequency component obtained by the fast Fourier transform is at least the commercial frequency component (the frequency component of the commercial power supply), which is 60 Hz in the Kansai region of Japan and 50 Hz in the Kanto region of Japan. The output of this fast Fourier transform unit is accurate enough to reliably detect a ground fault in an AC power supply based on the calculation result for one wavelength of commercial frequency (16.7 ms for Kansai and 20 ms for Kanto). can be obtained.

The AC ground fault determination unit determines an AC ground fault when the commercial frequency component frequency-analyzed by fast Fourier transform operation exceeds a threshold value for determining a ground fault in the AC electric circuit. It is possible to reliably determine the AC ground fault within a short time of about 16.7 to 20 ms from the time of occurrence. This ground fault determination unit is also realized by an AC ground fault determination program that can be executed by the same arithmetic processing unit as the fast Fourier transform unit, thereby simplifying the configuration and reducing the manufacturing cost. It goes without saying that this is possible.

The malfunction prevention unit prevents the DC ground fault determination output unit from outputting a determination of a DC ground fault from the time when the AC ground fault determination unit determines an AC ground fault. A switch section that does not output a DC ground fault judgment while judging an AC ground fault in , or a switch section that does not input a potential difference signal to the DC ground fault judgment output section while judging an AC ground fault can be considered. .

Therefore, when a ground fault occurs in the high-voltage distribution line of a substation, the AC ground fault determination unit quickly and reliably determines the ground fault by making full use of the fast Fourier transform, and the malfunction prevention unit detects the DC ground fault. Since malfunction of the discrimination output unit can be prevented, malfunction of the DC high-voltage grounding relay due to ground fault in the high-voltage distribution line in the substation is eliminated, and reliability is improved accordingly.

A third invention comprises a potential difference measuring unit provided between a grounding mat and a return wire of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. A DC ground fault detection output unit that outputs output, a current measurement unit that measures the current flowing in the electric circuit between the grounding mat and the return line, and an auxiliary that is charged using the rail potential generated between the grounding mat and the return line a power supply unit, an effective value calculation unit for calculating an effective value from at least the output of the current measurement unit using the power charged in the auxiliary power supply unit, and an effective value calculated by the effective value calculation unit for the AC electric circuit an AC ground fault determination unit that determines an AC ground fault when a threshold value for determining a ground fault is exceeded; and a DC ground fault by the DC ground fault determination output unit when the AC ground fault is determined by the AC ground fault determination unit. There is provided an erroneous detection prevention type DC high voltage grounding relay characterized by comprising a malfunction prevention part for blocking the judgment output of. (Claim 3)

The current measuring unit measures the current flowing in the electric circuit between the grounding mat and the return wire. , the magnitude of the current on the secondary side is preferably converted into a measurable magnitude for measurement. That is, when there is a change in the current flowing through the primary side of the current transformer, the change in the magnetic flux density excited by this causes a current of a magnitude divided by the turns ratio to flow in the secondary side, causing an AC ground fault. occurs, a secondary current proportional to the magnitude of the AC ground fault flows and can be measured.

The ground mat is grounded to the ground potential of the substation via grounding resistors, whereas the potential of the return line connected to the rail at a remote location with respect to this ground mat is above it. Since current flows through the running train, some rail potential is generated between the grounding mat and the return line, and the auxiliary power supply section is charged using this rail potential. Always charged. The auxiliary power supply unit may be a secondary battery that can be charged and discharged, but it is preferable to use a capacitor with a simpler configuration. More preferably, an electric double layer capacitor is used to increase the capacity.

The electric power charged in the auxiliary power supply section is used by the effective value calculation section to calculate the effective value using the current measured by the current measurement section. Further, it is needless to say that the measurement accuracy can be improved by obtaining the average value of the obtained instantaneous effective values as the effective value. The effective value calculator may be, for example, an arithmetic processing unit and an effective value arithmetic program executable by the arithmetic processing unit. The effective value obtained by the effective value calculator is of a magnitude that can accurately determine the magnitude of the AC ground fault current in a short period of about half of 16.7 to 20 ms of one cycle from the occurrence of the AC ground fault.

Since the AC ground fault determination unit determines an AC ground fault when the effective value exceeds the threshold for determining a ground fault in the AC electric circuit, within several ms to several tens of ms from the time when the AC ground fault occurs It is possible to reliably determine an AC ground fault in a short period of time. This ground fault determination unit is also realized by an AC ground fault determination program that can be executed by the same arithmetic processing unit as the fast Fourier transform unit, thereby simplifying the configuration and reducing the manufacturing cost. It goes without saying that this is possible.

The malfunction prevention unit prevents the DC ground fault determination output unit from outputting a determination of a DC ground fault from the time when the AC ground fault determination unit determines an AC ground fault. A switch section that does not output a DC ground fault judgment while judging an AC ground fault in , or a switch section that does not input a potential difference signal to the DC ground fault judgment output section while judging an AC ground fault can be considered. .

Therefore, when a ground fault occurs in the high-voltage distribution line of a substation, the AC ground fault determination unit quickly and reliably determines the ground fault by making full use of the calculation of the effective value, and the malfunction prevention unit determines the DC ground fault. Since the malfunction of the fault determination output section can be prevented, the malfunction of the DC high voltage grounding relay due to the ground fault of the high voltage distribution line in the substation is eliminated, and the reliability is improved accordingly.

A fourth invention comprises a potential difference measuring unit provided between a grounding mat and a return wire of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. a DC ground fault determination output unit for outputting; an AC ground fault determination unit for determining an AC ground fault when the potential difference between the grounding mat and the return line exceeds a threshold value for determining a ground fault in the AC electric circuit; Provided is an erroneous detection prevention type DC high voltage grounding relay characterized by comprising a malfunction prevention unit that prevents the DC ground fault determination output unit from outputting a DC ground fault determination when the ground fault determination unit determines an AC ground fault. do. (Claim 4)

The AC ground fault determination unit compares the potential difference between the grounding mat and the return line with a threshold for determining a ground fault in the AC electric circuit, and if the potential difference between the grounding mat and the return line exceeds the threshold, AC ground faults can be determined instantaneously. That is, when a ground fault occurs in an AC circuit of a DC substation for electric railways, the potential of the return line connected to the rail at a remote location is stable, whereas the grounding of the DC substation for electric railways is An AC voltage close to the power supply voltage is applied to the mat, depending on the ground fault situation, and a large potential difference instantaneously occurs between the ground mat and the return wire compared to a DC ground fault.

It is preferable that the AC ground fault determination section quickly determine an AC ground fault when the instantaneous value of the potential difference exceeds the DC feeding voltage, and output an AC ground fault determination signal, for example, via a voltage dividing resistor. It is conceivable that it is a relay that inputs a voltage divided by The relay is preferably a non-contact relay using a semiconductor element capable of high speed response, but a contact relay may be used.

The malfunction prevention unit prevents the DC ground fault determination output unit from outputting a determination of a DC ground fault from the time when the AC ground fault determination unit determines an AC ground fault. A switch section that does not output a DC ground fault judgment while judging an AC ground fault in , or a switch section that does not input a potential difference signal to the DC ground fault judgment output section while judging an AC ground fault can be considered. .

Therefore, when a ground fault occurs in the high-voltage distribution line of the substation, the AC ground fault determination unit catches the rise of the AC voltage that caused the ground fault and quickly and reliably determines the ground fault, and the malfunction prevention unit can prevent the malfunction of the DC ground fault determination output section, the malfunction of the DC high voltage grounding relay due to the ground fault of the high voltage distribution line in the substation is eliminated, and the reliability is improved accordingly.

A fifth invention comprises a potential difference measuring unit provided between a grounding mat and a return line of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. A DC ground fault determination output unit for outputting, a current measurement unit for measuring the current flowing in the electric circuit between the grounding mat and the return wire, and a threshold value for determining a ground fault in the AC electric circuit based on the current measured by this current measurement unit. and an AC ground fault determination unit that determines an AC ground fault when the AC ground fault is determined by the AC ground fault determination unit. An erroneous detection prevention type DC high voltage grounding relay characterized by comprising a prevention part. (Claim 5)

The current measuring unit measures the current flowing in the electric circuit between the grounding mat and the return wire. , the magnitude of the current on the secondary side is preferably converted into a measurable magnitude for measurement. That is, when there is a change in the current flowing through the primary side of the current transformer, the change in the magnetic flux density excited by this causes a current of a magnitude divided by the turns ratio to flow in the secondary side, causing an AC ground fault. occurs, a secondary current proportional to the magnitude of the AC ground fault flows and can be measured.

The AC ground fault determination unit compares the current measured by the current measurement unit with a threshold for determining a ground fault in the AC electric circuit, and instantly determines an AC ground fault when the threshold is exceeded. is. In other words, when a ground fault occurs in the AC circuit of a DC substation for electric railways, a ground fault current flows through the grounding mat of the DC substation for electric railways, and a large fault current (alternating current) flows on the far rail side. ) flows.

The AC ground fault determination unit quickly determines an AC ground fault when the instantaneous value of the alternating current measured by the current measurement unit exceeds a threshold value used for determining a DC ground fault by the DC ground fault determination output unit, A relay that outputs a ground fault determination signal is preferable, and for example, a relay that receives an alternating current is conceivable. The relay is preferably a non-contact relay using a semiconductor element capable of high speed response, but a contact relay may be used.

The malfunction prevention unit prevents the DC ground fault determination output unit from outputting a determination of a DC ground fault from the time when the AC ground fault determination unit determines an AC ground fault. A switch section that does not output a DC ground fault judgment while judging an AC ground fault in , or a switch section that does not input a potential difference signal to the DC ground fault judgment output section while judging an AC ground fault can be considered. .

Therefore, when a ground fault occurs in the high-voltage distribution line of the substation, the AC ground fault determination unit catches the rise of the AC voltage that caused the ground fault and quickly and reliably determines the ground fault, and the malfunction prevention unit can prevent the malfunction of the DC ground fault determination output section, the malfunction of the DC high voltage grounding relay due to the ground fault of the high voltage distribution line in the substation is eliminated, and the reliability is improved accordingly.

A sixth invention comprises a potential difference measuring unit provided between a grounding mat and a return wire of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. an AC ground fault determination output unit that outputs an output; an AC ground fault determination unit that determines an AC ground fault when the output of the potential difference measurement unit exceeds a threshold value for determining a ground fault in the AC electric circuit; and the AC ground fault determination unit. an erroneous detection prevention type DC high voltage grounding relay characterized by comprising a malfunction prevention unit for preventing a DC ground fault determination output by the DC ground fault determination output unit when determining an AC ground fault by means of. (Claim 6)

The AC ground fault determination unit compares the potential difference measured by the potential difference measurement unit with a threshold for determining a ground fault in the AC electric circuit, and instantaneously when the potential difference measured by the potential difference measurement unit exceeds the threshold. AC ground fault is determined immediately. That is, when a ground fault occurs in an AC circuit of a DC substation for electric railways, the potential of the return line connected to the rail at a remote location is stable, whereas the grounding of the DC substation for electric railways is An AC voltage close to the power supply voltage is applied to the potential of the mat, depending on the ground fault situation, and the potential difference measuring unit instantaneously measures a larger potential difference than the DC ground fault.

When the instantaneous value of the potential difference exceeds the threshold value used for determining a DC ground fault by the DC ground fault determination output section, the AC ground fault determination section quickly determines an AC ground fault and outputs an AC ground fault determination signal. For example, a relay for inputting a voltage obtained by dividing the voltage via a voltage dividing resistor can be considered. The relay is preferably a non-contact relay using a semiconductor element capable of high speed response, but a contact relay may be used.

The malfunction prevention unit prevents the DC ground fault determination output unit from outputting a determination of a DC ground fault from the time when the AC ground fault determination unit determines an AC ground fault. A switch section that does not output a DC ground fault judgment while judging an AC ground fault in , or a switch section that does not input a potential difference signal to the DC ground fault judgment output section while judging an AC ground fault can be considered. .

Therefore, when a ground fault occurs in the high-voltage distribution line of the substation, the AC ground fault determination unit catches the rise of the AC voltage that caused the ground fault and quickly and reliably determines the ground fault, and the malfunction prevention unit can prevent the malfunction of the DC ground fault determination output section, the malfunction of the DC high voltage grounding relay due to the ground fault of the high voltage distribution line in the substation is eliminated, and the reliability is improved accordingly.

A seventh invention comprises a potential difference measuring unit provided between a grounding mat and a return line of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. an AC ground fault determination output unit for outputting an AC ground fault, an AC ground fault determination unit for determining an AC ground fault when the potential difference occurring between the grounding mat and the return line exceeds a threshold value for determining a ground fault in the AC electric circuit, and the AC When the ground fault determination unit determines an AC ground fault, the switching unit disconnects the connection between the grounding mat and the return wire and the potential difference measurement unit, thereby preventing the DC ground fault determination output by the DC ground fault determination output unit. An erroneous detection prevention type DC high voltage grounding relay characterized by comprising a prevention part. (Claim 7)

The AC ground fault determination unit compares the potential difference between the grounding mat and the return line with a threshold for determining a ground fault in the AC electric circuit, and if the potential difference between the grounding mat and the return line exceeds the threshold, AC ground faults can be determined instantaneously. That is, when a ground fault occurs in an AC circuit of a DC substation for electric railways, the potential of the return line connected to the rail at a remote location is stable, whereas the grounding of the DC substation for electric railways is Depending on the ground fault situation, an AC voltage close to the power supply voltage is applied to the potential of the mat, and a large potential difference instantaneously occurs between the ground mat and the return wire compared to a DC ground fault. . It is preferable that the AC ground fault determination section quickly determine the AC ground fault when the instantaneous value of the potential difference exceeds the DC feeding voltage, and output an AC ground fault determination signal. Moreover, it is desirable to give a delay time of about 5 ms to the DC ground fault determination units that are likely to operate simultaneously.

The malfunction prevention unit includes a switch unit for disconnecting the connection between the grounding mat and the return line and the potential difference measurement unit when the AC ground fault determination unit determines that the AC ground fault has occurred. To prevent erroneous operation of DC ground fault determination by eliminating an input signal for DC ground fault determination when a ground fault occurs. Note that the switch section may be formed using a relay circuit for inputting a voltage divided through voltage dividing resistors, for example. The relay circuit is preferably a contact relay that generates almost no contact resistance, but a non-contact relay using a semiconductor device capable of high-speed response may be used.

Therefore, when a ground fault occurs in the high-voltage distribution line of a substation, the AC ground fault determination unit detects the rise of the AC voltage that caused the ground fault and quickly determines the ground fault. Since the malfunction of the ground fault determination output section can be prevented, the malfunction of the DC high voltage grounding relay due to the ground fault of the high voltage distribution line in the substation can be prevented, and the reliability is improved accordingly.

The eighth invention comprises a potential difference measuring unit provided between a grounding mat and a return line of a DC substation for electric railways and measuring the potential difference, and determining a DC ground fault using the potential difference and generating a DC ground fault signal. When the potential difference generated between the output DC ground fault determination output unit and the ground mat and return wire is caused by a ground fault in the AC circuit, the DC ground fault determination output unit erroneously detects the potential difference due to this AC ground fault. an AC ground fault voltage suppressing circuit that attenuates to the extent that it does not cause a malfunction, interposed between the grounding mat and the return wire, and the DC ground fault determination output unit, thereby preventing a DC ground fault determination output. To provide a DC high-voltage grounding relay with a characteristic false detection prevention type. (Claim 8)

The AC ground fault voltage suppression circuit is an attenuating circuit that attenuates the potential difference between the grounding mat and the return line to the extent that the DC ground fault judgment output unit does not erroneously detect the ground fault in the AC electric circuit when the potential difference occurs. is preferable, and it is preferable to use a passive filter such as a low-pass filter or a notch filter that can attenuate 6600 V of the commercial power frequency of 50 to 60 Hz to at least 2000 V or less, preferably 400 V or less, but an active filter may also be used.

The malfunction prevention unit interposes the AC ground fault voltage suppressing circuit between the ground mat and the return wire and the DC ground fault judgment output unit, thereby preventing the ground mat and the return wire caused by a ground fault in the AC electric circuit. By inputting to the DC ground fault determination output section in a state in which the potential difference between the voltages is sufficiently attenuated, it is possible to prevent the determination output of the DC ground fault.

Therefore, even if a ground fault occurs in the high-voltage distribution line of the substation, the DC ground fault determination output section is in a state where the AC voltage at which the ground fault has occurred is attenuated by the AC ground fault voltage suppression circuit of the malfunction prevention section. Since it is possible to prevent malfunction of the DC ground fault determination output section by inputting to the , the DC high voltage grounding relay will not malfunction due to the ground fault of the high voltage distribution line in the substation, and the reliability will be improved accordingly. do.

When the potential difference measuring unit and the DC ground fault determination output unit are units of an existing DC high voltage grounding relay, and the malfunction prevention unit is interposed between this existing DC high voltage grounding relay, the grounding mat, and the return wire ( In claim 9), when an existing DC high voltage ground fault relay is connected between the grounding mat and the return line, the malfunction prevention part is interposed to prevent the ground fault in the secondary line of the high voltage distribution transformer. It is possible to quickly determine a DC ground fault and output a DC ground fault signal without being affected by a failure.

As described above, according to the erroneous detection prevention type DC high-voltage grounding relay of the present invention, the influence of a ground fault or the like on the secondary side line of a high-voltage distribution transformer can be quickly determined, Since the output of the DC ground fault determination of the fault determination output unit can be blocked, malfunction of the DC high voltage ground relay can be prevented, and obstruction to train operation can be prevented.

According to the erroneous detection prevention type DC high voltage grounding relay of the first invention, the fast Fourier transform section performs frequency analysis of the potential difference generated between the grounding mat and the return line by the fast Fourier transform, and the AC ground fault determination section uses the commercial power supply. It is possible to accurately and quickly determine a ground fault caused by an AC ground fault using the magnitude of the frequency component of , and the malfunction prevention unit prevents the determination output of a DC ground fault when a ground fault occurs due to an AC ground fault. can be done.

According to the erroneous detection prevention type DC high voltage grounding relay of the second invention, the fast Fourier transform section analyzes the frequency of the current flowing between the grounding mat and the return wire by fast Fourier transform, A ground fault due to an AC ground fault can be determined accurately and quickly using the magnitude of the frequency component. can.

According to the erroneous detection prevention type DC high voltage grounding relay of the third invention, the effective value calculation unit calculates the effective value using the current flowing between the grounding mat and the return wire, and uses the magnitude of this effective value A ground fault due to an AC ground fault can be determined accurately and quickly, and the malfunction prevention unit can block a determination output of a DC ground fault when a ground fault due to an AC ground fault occurs.

According to the erroneous detection prevention type DC high voltage grounding relay of the fourth invention, when the potential difference between the grounding mat and the return wire exceeds the threshold, it is possible to quickly determine the AC ground fault, and the malfunction prevention unit It is possible to prevent the determination output of the DC ground fault when a failure occurs.

According to the erroneous detection prevention type DC high voltage grounding relay of the fifth invention, when the magnitude of the current flowing in the electric circuit between the grounding mat and the return line exceeds the threshold, it is possible to quickly determine the AC ground fault, and the malfunction prevention unit It is possible to prevent the determination output of a DC ground fault when a ground fault occurs due to an AC ground fault.

According to the erroneous detection prevention type DC high-voltage grounding relay of the sixth invention, when the output of the potential difference measuring unit exceeds the threshold value, the AC ground fault can be quickly determined, and the malfunction prevention unit is activated when a ground fault occurs due to the AC ground fault. It is possible to prevent the determination output of the DC ground fault.

According to the erroneous detection prevention type DC high voltage grounding relay of the seventh invention, when the potential difference between the grounding mat and the return line exceeds the threshold value, the AC ground fault is quickly determined, and the switch section of the malfunction prevention section detects the grounding mat , and the connection between the return line and the DC ground fault determination output unit, and the DC ground fault determination output can be blocked when a ground fault occurs due to an AC ground fault.

According to the erroneous detection prevention type DC high voltage grounding relay of the eighth aspect of the invention, the potential difference due to the AC ground fault is attenuated by the AC ground fault voltage suppressing circuit of the malfunction prevention section, and erroneous detection can be prevented by the DC ground fault determination output section. Therefore, it is possible to prevent the determination output of the DC ground fault when a ground fault occurs due to the AC ground fault.

The malfunction prevention part is interposed between the existing DC high voltage grounding relay, the grounding mat and the return wire, so that the existing DC high voltage grounding relay is utilized to form a false detection type DC high voltage grounding relay. becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of a DC electric railway substation in which an erroneous detection prevention type DC high voltage earthing relay according to the present invention is installed; 1 is a diagram showing a configuration of an erroneous detection prevention type DC high voltage grounding relay according to a first embodiment; FIG. FIG. 10 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay according to a second embodiment; FIG. 11 is a diagram showing the configuration of a misdetection prevention type DC high voltage grounding relay according to a third embodiment; FIG. 12 is a diagram showing the configuration of an erroneous detection prevention type DC high-voltage grounding relay according to a fourth embodiment; FIG. 11 is a diagram showing the configuration of an erroneous detection prevention type DC high-voltage grounding relay according to a fifth embodiment; FIG. 12 is a diagram showing the configuration of an erroneous detection prevention type DC high-voltage grounding relay according to a sixth embodiment; FIG. 14 is a diagram showing the configuration of an erroneous detection prevention type DC high-voltage grounding relay according to a seventh embodiment; FIG. 20 is a diagram showing the configuration of an erroneous detection prevention type DC high-voltage grounding relay according to an eighth embodiment; FIG. 10 is a diagram showing an example of an AC ground fault voltage suppression circuit in the erroneous detection prevention type DC high voltage grounding relay of FIG. 9; FIG. 20 is a diagram showing the configuration of a DC railway substation in which a misdetection prevention type DC high-voltage earthing relay according to a ninth embodiment is installed; FIG. 20 is a diagram showing the configuration of an erroneous detection prevention type DC high-voltage grounding relay according to a ninth embodiment; FIG. 20 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay according to a tenth embodiment; 1 is a diagram showing the configuration of a DC substation for electric railways to which a conventional DC high-voltage earthing relay is installed; FIG. 1 is a diagram showing a configuration of a conventional DC high-voltage grounding relay; FIG. It is a figure which shows the alternating voltage waveform of a high voltage distribution line.

FIG. 1 is a diagram showing the configuration of a DC electric railway substation in which the false detection prevention type DC high voltage grounding relay of the present invention is installed, and FIG. 2 is the configuration of the false detection prevention type DC high voltage grounding relay according to the first embodiment. It is a figure which shows. 1 and 2, a specific embodiment of an erroneous detection prevention type DC high voltage grounding relay according to a first embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, an erroneous detection prevention type DC high voltage grounding relay 1 is provided between a grounding mat 3 and a return line 4 of a substation 2, and measures a potential difference between the grounding mat 3 and the return line 4. It has a measurement unit 5 and a DC ground fault judgment output unit 6 that judges a ground fault using the measured potential difference. In addition, the power line in the substation 2 includes a high voltage line 2A that supplies AC power to the loads R of each facility such as traffic lights, lighting, escalators, and ticket vending machines via a high voltage distribution transformer 7A, and a rectifier transformer. The power converted to DC by the rectifier 8 via 7B is divided into a DC distribution line (DC bus) 2B that supplies the power to the feeder 9, and Ba is a circuit breaker that cuts off the power supply to the high voltage distribution transformer 7A. Bb is a circuit breaker for interrupting the power supply to the rectifying transformer 7B, and 8A is a DC high-speed circuit breaker for interrupting the power supply to the feeder 9 at high speed.

As shown in FIG. 2, the erroneous detection prevention type DC high-voltage grounding relay 1 of the present invention includes the potential difference measuring unit 5 and the DC ground fault determination output unit 6, as well as the grounding mat 3 and the return line 4. A fast Fourier transform unit 11 that performs a fast Fourier transform operation on the output of the potential difference measuring unit 5 using the power charged in the auxiliary power unit 10, and this an AC ground fault determination unit 12 that determines an AC ground fault when the commercial frequency component calculated by the fast Fourier transform unit 11 exceeds a threshold for determining a ground fault in the AC electric circuit; A malfunction prevention unit 13 for blocking the DC ground fault signal Fd of the DC ground fault from the DC ground fault determination output unit 6 when determining the ground fault.

Since the grounding mat 3 is buried under the substation 2, it can be considered to be connected to the true grounding point G via the resistance value 3R. On the other hand, the rails where the return line 4 is located away from the substation 3 can be considered to be connected from the true ground point G via the rail leakage resistor 4R. Here, if a ground fault occurs at the fault location F in the high-voltage line 2A, it is considered that the fault location F is connected to the nearest grounding mat 3 by the resistor 2R.

The potential difference measuring section 5 includes a voltage dividing resistor 5A for dividing the voltage applied between the return line 4 and the grounding mat 3, and a rectifier 5B connected in parallel to the potential difference measuring section 5 with the return line 4 and the grounding mat 3 in the forward direction. and measures the positive potential difference of the grounding mat 3 with the return line 4 as a reference.

The DC ground fault determination output unit 6 determines that the potential difference measured by the potential difference measurement unit 5 reaches a set value that serves as a reference for a DC ground fault, and a DC ground fault determination unit 6A that determines that a DC ground fault has occurred. and a ground fault determination output section 6B for outputting a determination result determined by the DC ground fault determination section 6A as a DC ground fault signal Fd. It forms part 13 . Reference numeral 6C denotes a ground fault display unit formed using an LED or the like so that the DC ground fault signal Fb can be visually confirmed.

The auxiliary power supply unit 10 preferably includes, for example, an electric double layer capacitor and a charge/discharge control circuit for the electric double layer capacitor, and is always charged and has a long life. That is, while the train is running, a rail voltage of approximately 200 to 300 V is generated between the ground mat 3 and the return wire 4, and this rail voltage can be used to charge the electric double layer capacitor. As a result, the fast Fourier transform section 11 can use the electric power charged in the auxiliary power supply section 10 to perform fast Fourier transform arithmetic processing. Further, in this embodiment, the electric power charged in the auxiliary power supply unit 10 is also used to supply power to the AC ground fault determination unit 12 , the malfunction prevention unit 13 and the DC ground fault determination output unit 6 . This makes it possible to correctly determine a ground fault even when the power supply from the outside is interrupted.

The fast Fourier transform unit 11 performs fast Fourier transform on the output of the potential difference measuring unit 5 and supplies the output to the AC ground fault determination unit 12 . The arithmetic processing of this fast Fourier transform is performed at least on the frequency component of the commercial power source (that is, the commercial frequency component), which is 60 Hz in the Kansai region of Japan and 50 Hz in the Kanto region of Japan. The commercial frequency component obtained by processing this fast Fourier transform for one cycle of the commercial power supply (that is, 16.7 ms or 20 ms) is the potential difference between the grounding mat 3 and the return line 4 containing various noise components. This serves as a guideline for determining that the AC voltage due to the ground fault of the line 2A is definitely included. The fast Fourier transform unit 11 may be formed by making full use of hardware such as a programmable logic device (FPGA). Cost can be reduced.

Similarly, each of the units 6, 12, and 13 has a program executable by an arithmetic processing unit such as a microcomputer (although not shown, a DC ground fault determination program, an AC ground fault determination program, a malfunction prevention program, etc.). may be implemented using

The AC ground fault determination unit 12 determines a ground fault in the high-voltage line 2A, and the magnitude of the commercial frequency component calculated by the fast Fourier transform unit 11 exceeds a threshold for determining a ground fault in the AC line. It sometimes determines an AC ground fault. When this threshold reaches 2000 V, far exceeding the set value of 400 to 600 V, which is the set value for determining a DC ground fault by the DC ground fault determination unit 6A, there is a possibility of false detection. This AC ground fault is determined. By using the commercial frequency component subjected to the fast Fourier transform, it is possible to reliably determine the ground fault of the high-voltage line 2A in a short time of about several tens of milliseconds. A double frequency component of the commercial frequency may be calculated, and the magnitude of the double frequency component may be used as a criterion for further speeding up.

The malfunction prevention unit 13 outputs the DC ground fault signal Fd from the DC ground fault determination output unit 6 when the AC ground fault determination unit 12 determines a ground fault in the high-voltage line 2A. The DC ground fault signal Fd of the ground fault is blocked, and more specifically, the DC ground fault signal Fd is cut off using a switch circuit. As a result, even if the DC ground fault determination unit 6A determines that a DC ground fault has occurred due to a potential difference fluctuation due to a ground fault in the high-voltage line 2A, the DC ground fault signal Fd for the DC ground fault is output. It is configured so that it does not happen.

Note that the malfunction prevention unit 13 may be any device as long as it can block the DC ground fault signal Fd from the DC ground fault determination output unit 6. and the ground fault determination output section 6B.

By using the erroneous detection prevention type DC high voltage grounding relay 1 having the above configuration, when a DC ground fault occurs in the DC distribution line (DC bus) 2B, the return line 4 is affected by the ground fault current caused by this. The potential of the grounding mat 3 with respect to the abruptly increases, and the potential difference measurement unit 5 measures this potential difference. When the potential difference exceeds a set value (for example, 400 V to 600 V) for ground fault determination, the DC ground fault determination output unit 6 outputs a DC ground fault signal Fd for DC ground fault, so that the high-speed circuit breaker 8A and the circuit breaker Bb can be cut off immediately to minimize the damage caused by a large fault current. Therefore, the high voltage line 2A is not adversely affected.

On the other hand, when an AC ground fault occurs at the fault location F of the high-voltage line 2A of the substation 2, the power supplied to this fault location F is supplied to the grounding mat 3 via the resistor 2R. , an AC voltage close to the power supply voltage (3300 V or 6600 V) is applied to the ground mat 3 . At this time, the potential difference measuring unit 5 measures an extremely large AC potential difference (waveform half-wave rectified by the rectifier 5B).

The fast Fourier transform unit 11 always analyzes the commercial frequency component of the potential difference measured by the potential difference measurement unit 5, and detects the difference during at least one cycle (16.6 ms to 20 ms) of the commercial power supply from the time when the AC ground fault occurs. The commercial frequency component of the AC ground fault appears largely in . The AC ground fault determination unit determines a ground fault in the high voltage line 2A when the commercial frequency component obtained by the fast Fourier transform unit 11 exceeds a predetermined threshold value, and the malfunction prevention unit 13 determines a DC ground fault. The DC ground fault signal Fd of the DC ground fault from the determination output unit 6 is blocked.

Therefore, when an AC ground fault occurs, the malfunction prevention unit 13 first determines a ground fault in the high-voltage line 2A, and even if the DC ground fault determination output unit 6 malfunctions due to a large AC potential difference, the DC Malfunction can be prevented by blocking the DC ground fault signal Fd of the ground fault. Although not shown, a ground fault is also detected on the side of the high-voltage line 2A and the circuit breaker Ba is interrupted. The potential becomes equal to or lower than the set value of the DC ground fault determined by the DC ground fault determination output unit 6, thereby recovering the state in which the DC ground fault can be detected.

That is, in the erroneous detection prevention type DC high-voltage grounding relay 1 of the present embodiment, it is possible to eliminate the malfunction of outputting the DC ground fault signal Fd of the DC ground fault due to the ground fault in the high-voltage line 2A. The ground fault in 2A does not cut off the power supply to the DC electric line 2B, and the operation of the train is not adversely affected.

FIG. 3 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 15 according to the second embodiment. 3 is different from the erroneous detection prevention type DC high voltage earthing relay 1 shown in FIG. The Fourier transform section 11 performs frequency analysis of the AC current measured by the current measurement section 16 . Other components are the same as or equivalent to those already described in detail with reference to FIG. 2, so detailed description thereof will be omitted.

The current measuring unit 16 uses, for example, a current transformer that is excited by the current flowing in the electric circuit on the primary side by electromagnetic induction and causes the current to flow to the secondary side, and the magnitude of the current on the secondary side is set to a size that can be measured. It is preferable to convert and measure. That is, when there is a change in the current flowing through the primary side of the current transformer, the change in the magnetic flux density excited by this causes a current of a magnitude divided by the turns ratio to flow in the secondary side, causing an AC ground fault. occurs, a secondary current proportional to the magnitude of the AC ground fault flows and can be measured.

The current transformer can efficiently convert and measure an alternating current that constantly fluctuates in the electric path between the grounding mat 3 and the return line 4 . Also, when a DC current flows through the electric path between the grounding mat 3 and the return wire 4, the current transformer does not transmit the DC current, so that the DC current is not detected. In addition, since the current flowing in the electric circuit between the grounding mat 3 and the return line 4 flows in both forward and reverse directions, it is possible to accurately analyze the commercial frequency component of the alternating current generated when a ground fault occurs in the high voltage line 2A. can do.

That is, the AC ground fault determination unit 6 can more reliably determine a ground fault in the high-voltage line 2A, and the malfunction prevention unit 13 prevents the DC ground fault determination output unit 6 from making a determination due to a malfunction associated with an AC ground fault. The output can be quickly and reliably blocked.

FIG. 4 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 20 according to the third embodiment. In FIG. 4, the difference from the erroneous detection prevention type DC high voltage earthing relay 1 shown in FIG. Reference numeral 12 is that an AC ground fault is determined when the effective value calculated by the effective value calculator 21 exceeds a threshold for determining a ground fault in the AC electric circuit. Other components are the same as or equivalent to those already described in detail with reference to FIGS. 2 and 3, so detailed description thereof will be omitted.

The effective value calculation unit 21 performs effective value calculation processing using the electric power charged in the auxiliary power supply unit 10, so that the effective value calculation can always be performed even when the power supply from the outside is interrupted. . Note that the effective value is always a positive value and fluctuates at a cycle twice the commercial frequency. Therefore, by calculating the average value of the effective values of the AC current measured by the current measuring unit 16 by the effective value calculating unit 21, it is possible to obtain a guideline indicating the magnitude of the ground fault in the high-voltage line 2A more quickly. can.

Also, the effective value calculation unit 21 may be one that obtains the effective value by combining electronic circuits. Therefore, the manufacturing cost may be reduced.

FIG. 5 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 25 according to the fourth embodiment. 5 differs from the erroneous detection prevention type DC high voltage grounding relays 1, 15 and 20 shown in FIGS. is provided with an AC ground fault determination unit 26 that determines an AC ground fault when the voltage exceeds a predetermined threshold value (for example, a DC feeding voltage of 1500 V) for determining a ground fault in the AC electric circuit. Since the other points are the same as or equivalent to those explained using FIGS. 1 to 3, the explanation thereof is omitted.

Note that the AC ground fault determination unit 26 includes, for example, a voltage dividing resistor interposed between the grounding mat 3 and the return line 4, and a switching switch when the voltage divided by the voltage dividing resistor exceeds the input threshold value. and a switching circuit, the switching circuit being, for example, a relay circuit. That is, by supplying the voltage-adjusted AC voltage to the AC excitation coil of the relay circuit, the excitation voltage of the relay coil is used as a threshold, and the b contact of the relay circuit is used as the malfunction prevention unit 13, and the DC ground fault determination output unit 6 By interposing them on the output side, it is possible to configure the AC ground fault determination unit 26 and the malfunction prevention unit 13 with the simplest possible configuration.

As in the present embodiment, by configuring the AC ground fault determination unit 26 with passive elements that do not require advanced arithmetic processing, it becomes possible to eliminate the auxiliary power supply unit 10, thereby reducing the manufacturing cost accordingly. becomes possible.

FIG. 6 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 30 according to the fifth embodiment. 6 differs from the erroneous detection prevention type DC high voltage grounding relay 20 shown in FIG. An AC ground fault determination unit 31 that determines an AC ground fault when exceeding a predetermined threshold (for example, a current corresponding to a DC feeding voltage) for determining a ground fault in an AC electric circuit without adding arithmetic processing. It is a point to be prepared. Other points are the same as those of the third embodiment already described with reference to FIG. 4, so detailed description thereof will be omitted.

As in the present embodiment, the AC ground fault determination unit 31 has a simple configuration that only compares with a threshold value. can be eliminated, and the manufacturing cost can be reduced accordingly.

FIG. 7 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 35 according to the sixth embodiment. 7 differs from the erroneous detection prevention type DC high voltage grounding relay 1 shown in FIG. is provided with an AC ground fault determination unit 36 that determines an AC ground fault when the ground fault determination threshold value (for example, a DC feeding voltage of 1500 V) is exceeded. Other components are the same as or equivalent to those already described in detail with reference to FIG. 2, so detailed description thereof will be omitted.

As in the present embodiment, the AC ground fault determination unit 36 of the present embodiment has a simple configuration that only performs comparison with a threshold value, so that it can be configured by passive elements that do not require advanced arithmetic processing. , the auxiliary power supply unit 10 can be eliminated, and the manufacturing cost can be reduced accordingly.

FIG. 8 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 40 according to the seventh embodiment. 8 is different from the erroneous detection prevention type DC high-voltage earthing relay 25 shown in FIG. , the DC ground fault determination output unit 6 is completely separated from the grounding mat 3 and the return line 4 .

The erroneous detection prevention type DC high voltage grounding relay 40 of the present embodiment operates when the potential difference generated between the grounding mat 3 and the return wire 4 exceeds a threshold for determining a ground fault in the AC electric circuit (for example, a DC feeding voltage of 1500 V). AC ground fault determination unit 41 for determining an AC ground fault, and connection between the grounding mat 3 and return line 4 and the DC ground fault determination output unit 6 when the AC ground fault determination unit 41 determines an AC ground fault. and a malfunction prevention unit 42 for preventing the determination output of the DC ground fault signal Fd by the DC ground fault determination output unit 6 by a switch unit 42A for disconnecting the DC ground fault signal Fd.

More specifically, the malfunction prevention unit 42 is a relay circuit, and when an AC voltage is applied to the AC-excited relay coil 41B through the voltage dividing circuit 41A and the AC voltage supplied to the relay coil 41B exceeds the threshold value Then, the potential difference measuring section 5 is separated from the grounding mat 3 and the return line 4 by opening the b contact of the switch section 42A. Other members are the same as or equivalent to those shown in FIG.

According to the erroneous detection prevention type DC high-voltage grounding relay 40 of the seventh embodiment, when no AC voltage is applied between the grounding mat 3 and the return line 4 due to a ground fault in the high-voltage line 2A, the relay coil Since no potential difference is applied to 41B, the switch section 42A connects the potential difference measuring section 5 between the grounding mat 3 and the return wire 4. Therefore, if a ground fault occurs in the DC distribution line 2B, the DC grounding failure occurs. The fault determination output unit 6 detects this and outputs a DC ground fault signal Fd.

On the other hand, when an AC voltage is applied between the grounding mat 3 and the return wire 4 due to a ground fault in the high-voltage line 2A, the DC ground fault determination output unit 6 is operated, the b contact of the switch portion 42A is opened. That is, the malfunction prevention unit 42 disconnects the DC ground fault determination unit 6 from between the grounding mat 3 and the return wire 4, thereby reliably preventing malfunction.

FIG. 9 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 45 according to the eighth embodiment. 9 differs from the erroneous detection prevention type DC high voltage grounding relay 40 shown in FIG. is caused by a ground fault in the AC electric circuit, the AC ground fault voltage suppression circuit 47 outputs the potential difference Vo that is attenuated to such an extent that the potential difference Vi due to the AC ground fault is not erroneously detected by the DC ground fault judgment output unit 6. is interposed between the grounding mat 4 and the return line 3 and the DC ground fault determination output section 5 to prevent the determination output of the DC ground fault signal Fd. Other parts are the same as those already described in detail with reference to FIG. 8, so detailed description thereof will be omitted by denoting the same or equivalent members with the same reference numerals.

FIG. 10 is a diagram showing an example of the AC ground fault voltage suppression circuit 47. As shown in FIG. As shown in FIG. 10, the AC ground fault voltage suppressing circuit 47 is considered to attenuate, for example, the AC voltage of the commercial power supply with the potential difference Vi. is applied, the filter circuit converts the potential difference into a potential difference Vo that is attenuated to a level lower than the set value of the DC ground fault determination output unit 6 .

FIG. 10A is a diagram showing the configuration of a low-pass filter circuit as an example of the AC ground fault voltage suppression circuit.

As shown in FIG. 10(A), a low-pass filter circuit 47A as an example of the AC ground fault voltage suppression circuit 47 includes a variable resistor R and a capacitor C connected in series, and between one end of the variable resistor R and an intermediate point. and a coil L connected to the According to this low-pass filter circuit 47A, the AC component of the potential difference Vi can be attenuated with characteristics determined by the sizes of resistors R1 and R1 divided by the intermediate point of the variable resistor R, the size of the coil L, and the capacity of the capacitor C. . Note that each element R1, R2, L. The magnitude of C is when, even if a commercial power supply of 6600 V is applied to the potential difference Vi, the AC output potential difference Vo becomes equal to or less than the set value of the DC ground fault determination output section 6 at the commercial frequency and a DC ground fault occurs. is adjusted to minimize the rise delay of the potential difference Vi at .

In this example, a coil L is provided in parallel with the resistor R1 to reduce the load resistance of the DC component as much as possible, but this coil L can be omitted. That is, it goes without saying that the AC ground fault voltage suppression circuit 47 of the present invention may have a configuration in which the coil L is removed from the circuit configuration of the low-pass filter circuit 47A.

FIG. 10B is a diagram showing an example of a .pi.-type low-pass filter circuit as an example of the AC ground fault voltage suppression circuit.

As shown in FIG. 10B, a π-type low-pass filter circuit 47B as an example of the AC ground fault voltage suppression circuit 47 includes a resistor R3, a coil L1, a capacitor C1, and a It comprises a resistor R4, a coil L2, and a capacitor C2 which are sequentially connected in parallel, and outputs the potential difference Vi across the capacitor C1.

By using the π-type low-pass filter circuit 47 in which a plurality of stages of low-pass filter circuits are combined as in this example, the attenuation factor depending on the frequency can be increased. That is, it is possible to efficiently attenuate the potential difference Vi that accompanies an AC ground fault in the commercial power supply and convert it to a potential difference Vo that is sufficiently attenuated to the extent that it is not reliably detected, and at the same time, it is possible to suppress the attenuation of the DC potential difference. .

FIG. 10C is a diagram showing an example of a notch filter circuit as an example of the AC ground voltage suppression circuit.

As shown in FIG. 10(C), a notch filter circuit 47C as an example of the AC ground fault voltage suppression circuit 47 is connected between resistors R5 and R6 which are connected in sequence and between these resistors R5 and R6. It consists of a capacitor C3, capacitors C4 and C5 sequentially connected in parallel to these resistors R5 and R6, and a resistor R7 connected between these capacitors C4 and C5. is attenuated to Therefore, it is possible to efficiently attenuate the potential difference Vi associated with the AC ground fault of the commercial power supply and sufficiently attenuate it to the extent that it is not reliably detected, and to suppress the attenuation of the DC potential difference to the extent that it hardly occurs.

FIG. 11 is a diagram showing the configuration of a DC railway substation in which an erroneous detection prevention type DC high voltage grounding relay according to the ninth embodiment is installed, and FIG. It is a figure which shows the structure of a relay.

As shown in FIG. 11, the erroneous detection prevention type DC high voltage grounding relay 50 according to the ninth embodiment is connected to the conventional It connects the unit of the DC high voltage earthing relay 90 . The DC high-voltage grounding relay 90 also includes a potential difference measuring unit 5 that measures the potential difference between the grounding mat 3 and the return line 4, determines a ground fault using the measured potential difference, and outputs a DC ground fault signal Fd. It has a DC ground fault determination output unit 6 that

The power line in the substation 2 includes a high voltage line 2A that supplies AC power to loads R of facilities such as traffic lights, lighting, escalators, and ticket vending machines via a high voltage distribution transformer 7A, and a rectifying transformer 7B. DC power converted by a rectifier 8 is divided into a DC distribution line 2B that supplies power to a feeder 9, Ba is a circuit breaker that cuts off the power supply to the high voltage distribution transformer 7A, and Bb is a rectifying transformer. A circuit breaker for interrupting power supply to 7B and a DC high-speed circuit breaker for interrupting power supply to feeder 9 at high speed 8A.

Since the grounding mat 3 is buried under the substation 2, it can be considered to be connected to the true grounding point G via the resistance value 3R. On the other hand, the rails where the return line 4 is located away from the substation 3 can be considered to be connected from the true ground point G via the rail leakage resistor 4R. Here, if a ground fault occurs at the fault location F in the high-voltage line 2A, it is considered that the fault location F is connected to the nearest grounding mat 3 by the resistor 2R.

As shown in FIG. 12, in the erroneous detection prevention type DC high voltage grounding relay 50 of the ninth embodiment, the base 51 is configured to prevent a DC grounding fault of the DC high voltage grounding relay 90 when a ground fault occurs in the high voltage line 2A. The unit of the DC high voltage grounding relay 90 is completely separated from the grounding mat 3 and the return line 4 so that the judgment output section 6 does not malfunction.

The potential difference measuring section 5 includes a voltage dividing resistor 5A for dividing the voltage applied between the return line 4 and the grounding mat 3, and a rectifier connected in parallel to the potential difference measuring section 5 with the return line 4 and the grounding mat 3 as the forward direction. 5B. Reference numeral 6C denotes a ground fault display unit formed using an LED or the like so that the DC ground fault signal Fb can be visually confirmed.

The base 51 determines an AC ground fault when the potential difference between the grounding mat 3 and the return line 4 exceeds a threshold value (for example, a DC feeding voltage of 1500 V) for determining a ground fault in the AC electric circuit. A determination unit 52, and when the AC ground fault determination unit 52 determines an AC ground fault, disconnects the connection between the grounding mat 3 and the return line 4 and the DC high voltage ground relay 90 (the DC ground fault determination output unit 6 thereof). A malfunction prevention section 53 is provided for preventing the determination output of the DC ground fault signal Fd by the DC ground fault determination output section 6 by means of a switch section 53A.

More specifically, the malfunction prevention unit 53 is a relay circuit, and when an AC voltage is applied to the AC-excited relay coil 52B through the voltage dividing circuit 52A and the AC voltage supplied to the relay coil 52B exceeds the threshold value Then, the potential difference measuring section 5 is separated from the grounding mat 3 and the return line 4 by opening the b contact of the switch section 53A.

The unit of the DC high voltage grounding relay 90 is connected to the base 51 via the terminals 51A and 51B and the cable 51C, so that the DC high voltage grounding relay 90 is connected to the ground mat 3 and the return line 4 via the malfunction prevention section 53. connected between Thus, by interposing the terminals 51A, 51B and the cable 51C in the portion connecting the DC high voltage grounding relay 90 and the base 51, the unit of the DC high voltage grounding relay 90 can be easily replaced. The configuration is not limited to this configuration, and the terminals 51A and 51B may be connected so that the terminals 51A and 51B are fitted to each other without the cable 51C. A ground relay 90 unit may be connected to the base 51 .

According to the erroneous detection prevention type DC high-voltage grounding relay 50 of the ninth embodiment, when no AC voltage is applied between the grounding mat 3 and the return line 4 due to a ground fault in the high-voltage line 2A, the relay coil Since no potential difference is applied to 52B, the switch section 53A connects the potential difference measuring section 5 between the grounding mat 3 and the return wire 4. Therefore, if a ground fault occurs in the DC distribution line 2B, the DC grounding failure occurs. The fault determination output unit 6 detects this and outputs a DC ground fault signal Fd.

On the other hand, when an AC voltage is applied between the grounding mat 3 and the return line 4 due to a ground fault in the high-voltage line 2A, the DC ground fault determination output unit 6 is operated, the b contact of the switch portion 53A is opened. That is, the unit of the DC high-voltage grounding relay 90 is separated from between the grounding mat 3 and the return line 4 by the malfunction preventing portion 53, and its malfunction can be reliably prevented.

FIG. 13 is a diagram showing the configuration of an erroneous detection prevention type DC high voltage grounding relay 55 according to the tenth embodiment. 13 is different from the erroneous detection prevention type DC high voltage grounding relay 50 shown in FIG. That is the point.

When the potential difference between the grounding mat 3 and the return wire 4 is caused by a ground fault in the AC electric circuit, the malfunction prevention unit 57 detects the potential difference Vi caused by the AC ground fault by the DC ground fault judgment output unit 6. An AC ground fault voltage suppressing circuit 47 is provided for outputting the potential difference Vo attenuated to such an extent that it is not detected. The DC high voltage grounding relay 90 unit is connected to the base 56 via terminals 56A and 56B and a cable 56C. However, it goes without saying that these members 56A, 56B, and 56C can be omitted as appropriate, as already described in detail. Other parts are the same as those already described in detail with reference to FIG. 12, so detailed description thereof will be omitted by denoting the same or equivalent members with the same reference numerals. Also, the AC ground fault voltage suppression circuit 47 may have various configurations described with reference to FIG. 10 .

By interposing the malfunction prevention portion 57 having the above configuration in the base 56, even if a large AC voltage of about 6600 V is applied between the grounding mat 3 and the return line 4 due to a ground fault in the high voltage line 2A, this Since the AC component is sufficiently attenuated by the malfunction preventing section 57, the DC ground fault determination section 6 does not malfunction.

1, 15, 20, 25, 30, 35, 40, 45, 50, 55 DC high-voltage grounding relay for preventing false detection 2 Substation 2A High-voltage line 2B DC distribution line 3 Grounding mat 4 Return wire 5 Potential difference measuring unit 6 DC Ground fault determination output unit 7 Rectifier transformer 8 Rectifier 10 Auxiliary power supply unit 11 Fast Fourier transform unit 12, 26, 31, 36, 41, 52 AC ground fault determination unit 13, 42, 46, 53, 57 Malfunction prevention unit 16 Current measurement unit 21 Effective value calculation unit 42A, 53A Switch unit 47 AC ground fault voltage suppression circuit Fd DC ground fault signal

Claims (9)

A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
an auxiliary power supply that is charged using the rail potential generated between the ground mat and the return line;
a fast Fourier transform unit that performs a fast Fourier transform operation on the output of the potential difference measuring unit using the electric power charged in the auxiliary power supply unit;
an AC ground fault determination unit that determines an AC ground fault when the commercial frequency component calculated by the fast Fourier transform unit exceeds a threshold for determining a ground fault in the AC electric circuit;
A misdetection prevention type DC high voltage transformer, further comprising: a malfunction prevention unit for preventing a determination output of a DC ground fault signal by the DC ground fault determination output unit when the AC ground fault determination unit determines an AC ground fault. ground relay. A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
a current measuring unit that measures the current flowing in the electric circuit between the grounding mat and the return line;
an auxiliary power supply that is charged using the rail potential generated between the ground mat and the return line;
A fast Fourier transform unit that performs a fast Fourier transform operation on the output of the current measurement unit using the electric power charged in the auxiliary power supply unit;
an AC ground fault determination unit that determines an AC ground fault when the commercial frequency component calculated by the fast Fourier transform unit exceeds a threshold for determining a ground fault in the AC electric circuit;
A misdetection prevention type DC high voltage transformer, further comprising: a malfunction prevention unit for preventing a determination output of a DC ground fault signal by the DC ground fault determination output unit when the AC ground fault determination unit determines an AC ground fault. ground relay. A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
a current measuring unit that measures the current flowing in the electric circuit between the grounding mat and the return line;
an auxiliary power supply that is charged using the rail potential generated between the ground mat and the return line;
an effective value calculation unit that calculates an effective value from at least the output of the current measurement unit using the electric power charged in the auxiliary power supply unit;
an AC ground fault determination unit that determines an AC ground fault when the effective value calculated by the effective value calculation unit exceeds a threshold for determining a ground fault in the AC electric circuit;
A misdetection prevention type DC high voltage transformer, further comprising: a malfunction prevention unit for preventing a determination output of a DC ground fault signal by the DC ground fault determination output unit when the AC ground fault determination unit determines an AC ground fault. ground relay. A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
an AC ground fault determination unit that determines an AC ground fault when the potential difference between the grounding mat and the return wire exceeds a threshold for determining a ground fault in the AC electric circuit;
A misdetection prevention type DC high voltage transformer, further comprising: a malfunction prevention unit for preventing a determination output of a DC ground fault signal by the DC ground fault determination output unit when the AC ground fault determination unit determines an AC ground fault. ground relay. A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
a current measuring unit that measures the current flowing in the electric circuit between the grounding mat and the return line;
an AC ground fault determination unit that determines an AC ground fault when the current measured by the current measurement unit exceeds a threshold for determining a ground fault in the AC electric circuit;
A misdetection prevention type DC high voltage transformer, further comprising: a malfunction prevention unit for preventing a determination output of a DC ground fault signal by the DC ground fault determination output unit when the AC ground fault determination unit determines an AC ground fault. ground relay. A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
an AC ground fault determination unit that determines an AC ground fault when the output of the potential difference measurement unit exceeds a threshold for determining a ground fault in the AC electric circuit;
A misdetection prevention type DC high voltage transformer, further comprising: a malfunction prevention unit for preventing a determination output of a DC ground fault signal by the DC ground fault determination output unit when the AC ground fault determination unit determines an AC ground fault. ground relay. A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
an AC ground fault determination unit that determines an AC ground fault when a potential difference occurring between the grounding mat and the return wire exceeds a threshold for determining a ground fault in the AC electric circuit;
When the AC ground fault determination section determines an AC ground fault, the switch section for disconnecting the connection between the grounding mat and the return wire and the potential difference measurement section outputs the determination output of the DC ground fault signal by the DC ground fault determination output section. An erroneous detection prevention type DC high-voltage grounding relay, comprising: a malfunction prevention part for blocking. A potential difference measurement unit provided between a grounding mat and a return wire of a DC substation for electric railways to measure the potential difference, and a DC ground fault that determines a DC ground fault using the potential difference and outputs a DC ground fault signal. a judgment output unit;
AC ground fault voltage suppression that attenuates the potential difference caused by the AC ground fault to the extent that it does not cause false detection by the DC ground fault determination output unit when the potential difference between the grounding mat and the return line is caused by a ground fault in the AC circuit. An erroneous detection prevention type DC high voltage, characterized by comprising a circuit interposed between the grounding mat and the return line and the DC ground fault judgment output section to block the judgment output of the DC ground fault signal. ground relay. The potential difference measuring section and the DC ground fault determination output section are units of an existing DC high voltage grounding relay, and the malfunction prevention section is interposed between the existing DC high voltage grounding relay and the grounding mat and return line. The DC high voltage grounding relay according to claim 7 or claim 8.

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