JP2015067241A - Dc feeding protection control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC feeding protection control system capable of suitably detecting a high-resistance ground fault.SOLUTION: A DC feeding protection control system includes: a first switch and a second switch provided for a connection line connecting a rail to the ground; a first resistance and a second resistance which have smaller resistance values than ground resistance; a first voltage value measurement part which measures a first ground voltage value of the rail; a second voltage value measurement part which measures a second ground voltage value of the rail; a DC feeding protection relay device which outputs a signal for closing the first switch when the first ground voltage value is equal to or larger than a voltage threshold, and outputs a signal for closing the second switch when the second ground voltage value is equal to or larger than a voltage threshold; a first current value measurement part which measures the value of a first current flowing to a first transformer station; a second current value measurement part which measures the value of a second current flowing to a second transformer station. The DC feeding protection relay device determines whether a breaker or a switch is opened based upon the first current value and the second current value.

Description

  Embodiments described herein relate generally to a DC feeding protection control system.

  FIG. 11 is a configuration diagram showing a configuration of a general feeding system, and FIG. 12 is an equivalent circuit diagram of FIG.

Each of the substations SS _{1 to} SS ₄ shown in FIG. 11 is provided at intervals of several tens km, for example.

AC power supplied from an AC power source (not shown) of each of the substations SS _{1 to} SS ₄ is converted into DC power by a rectifier 901 and supplied to a feeder 902 and a rail 903. The rail 903 is connected to the ground 904 and grounded, and a high-resistance grounding resistance ρ is provided between the rail 903 and the ground 904.

When a ground fault occurs in the second section of the feeder 902, the ground fault current _Ie is sucked up from each place on the ground 904 (I _1x , I ₁ , I ₂ , I _{2x in} FIG. 11), and each substation SS. to return to the _{1 ~SS 4.}

11 and 12, a fault point interval length ratio d is the ratio of the substation SS ₂ when the distance from the substation SS ₂ to substation SS ₃ and 1. For example, when d = 0.5, it indicates that a failure occurs at an intermediate point between the substations SS ₂ and SS ₃ .

The combined resistance σR _t of each of the substations SS _{1 to} SS ₄ is represented by the following formula (1), and the ground fault current I _e is represented by the formula (2).

Here, R _s represents the combined resistance of the rectifier internal resistance and the power source impedance, and R _t represents the feeder resistance.

Here, E is a feeding voltage, R _f is a failure point resistance, and R _ρ is a simple combined resistance of a ground resistance.

When the rail 903 is grounded with a high resistance, the simple combined resistance R _ρ of the ground resistance is
R _ρ >> σR _t , R _f (3)
Therefore, the ground-fault current I _e is very small from the formula (2), and it is difficult to distinguish such a ground-fault current from the electric vehicle load current (electric vehicle running current).

  Therefore, as an example of ground fault detection, there is a method of detecting a voltage between the ground 904 and the rail 903 (rail ground voltage) and determining whether the detected voltage is equal to or higher than a predetermined threshold.

JP 2011-53189 A

However, since the ladder circuit of the rail resistance r and the ground resistance ρ is formed between the ground 904 and the rail 903 due to the resistance distribution between the ground 904 and the rail 903, the ground voltage E _re of the rail at each substation is expressed by the formula ( As shown in 4), the longer the distance L from the failure point, the smaller.

Here, _Eρ is a ground characteristic resistance voltage, and ε is a dielectric constant.

  FIG. 13 is an example showing the relationship between the rail ground voltage and the distance from the failure point at each substation.

As illustrated in FIG. 13, for example, when the interval between the substations SS _{1 to} SS ₄ is 10 km, the difference in the ground voltage E _re between the rails is small at each of the substations SS _{1 to} SS ₄ . Therefore, when the threshold value is set as shown in FIG. 13, the failure section spans a wide area of the substations SS _{1 to} SS ₄ despite the failure occurring between the substations SS ₂ and SS ₃ (second section). It will be judged.

  If it is determined as a failure section, a circuit breaker (not shown) or the like is opened and a power outage section is established. That is, a power outage section occurs over a wide area.

  Therefore, it is difficult for the above method to properly detect a high resistance ground fault.

  Therefore, in order to solve these problems, the embodiment of the present invention provides a DC feeding protection control system that can appropriately detect a high-resistance ground fault.

  In order to achieve the above object, the DC feeding protection control system according to the embodiment is provided on a first connection line that connects a rail grounded by a ground line to which a ground resistance is connected and the ground, and opens and closes an electric circuit. A first switch that is connected to the first connection line in series with the first switch; a second switch that opens and closes an electric circuit; and is connected to the first connection line in series with the first switch. A first resistor having a resistance value smaller than that of the resistor, and a second resistor connected in series with the second switch to the second connection line, and having a resistance value smaller than the ground resistance, and the first connection line A first voltage value measuring unit that is connected in parallel with one switch and the first resistor, and that measures a first ground voltage value of the rail in the first substation; the second switch and the second connection line; Connected in parallel with the second resistor The second voltage value measuring unit that measures the second ground voltage value of the rail at the second substation, and the first ground voltage value measured by the first voltage value measuring unit is a predetermined voltage. A signal for closing the first switch is output when the threshold voltage is equal to or greater than the threshold value, and the second switch is closed when the second ground voltage value measured by the second voltage value measurement unit is equal to or greater than the voltage threshold value. A DC feeder protective relay that outputs a signal, a first current value measuring unit that measures a first current value flowing from the first connection line into the first substation, and a second current from the second connection line. A second current value measuring unit that measures a second current value flowing into the two substations, and the DC feeding protective relay device includes a first current value measured by the first current value measuring unit, , Based on the second current value measured by the second current value measuring unit. There, it is determined whether or not to open the breaker or the switch.

1 is an overall configuration diagram showing a configuration of a DC feeding protection control system according to the present embodiment and peripheral devices thereof. The equivalent circuit diagram of FIG. 1 (when the switch is OFF). The equivalent circuit of FIG. 1 (when the switch is ON). The block diagram which shows the structure of the DC feeding protection relay apparatus which concerns on this embodiment. The block diagram which shows the structure of the calculating part of the DC feeding protection relay apparatus which concerns on this embodiment. The flowchart which shows operation | movement of the DC feeding protection relay apparatus which concerns on this embodiment. The flowchart which shows operation | movement of the calculating part of the DC feeding protection relay apparatus which concerns on this embodiment. The flowchart which shows operation | movement of the calculating part of the DC feeding protection relay apparatus which concerns on this embodiment. The flowchart which shows operation | movement of the DC feeding protection relay apparatus which concerns on this embodiment. The flowchart which shows operation | movement of the calculating part of the DC feeding protection relay apparatus which concerns on this embodiment. The block diagram which shows the structure of a general feeder system. FIG. 12 is an equivalent circuit diagram of FIG. 11. An example showing the relationship between the rail ground voltage and the distance from the fault at each substation of a general feeder system.

  Hereinafter, embodiments will be described with reference to the drawings.

(Embodiment)
FIG. 1 is an overall configuration diagram showing configurations of a DC feeding protection control system and peripheral devices according to the present embodiment. 2 is an equivalent circuit diagram of FIG. 1 (when the switch is OFF), and FIG. 3 is an equivalent circuit of FIG. 1 (when the switch is ON).

  A first substation 1 and a second substation 2 are connected to both ends of the feeder 3 in one section.

  The first substation 1 includes a rectifier 11 and a feeder circuit breaker 12. AC power supplied from an AC power source (not shown) is converted into DC power by the rectifier 11, passes through the feeder circuit breaker 12, and is supplied to one end of the electric wire 3.

  Similarly, the second substation 2 includes a rectifier 21 and a feeder circuit breaker 22. AC power supplied from an AC power source (not shown) is converted into DC power by the rectifier 21, passes through the feeder circuit breaker 22, and is supplied to the other end of the electric wire 3.

  The DC power converted by the rectifiers 11 and 21 is also supplied to the rail 4, and the feeder 3 and the rail 4 supply power to an electric vehicle (not shown).

  The rail 4 is connected to the ground 7 via a ground line 6 to which a ground resistance 5 having a high resistance value is connected and is grounded.

  The DC feeder protection control system 100 includes a first switch 101, a second switch 102, a first resistor 103, a second resistor 104, a first voltage value measuring unit 105, a second voltage value measuring unit 106, and a first current value measuring. Unit 107, second current value measuring unit 108, and DC feeding protective relay device 200.

  The first switch 101 is provided on a first connection line 8 that connects the rail 4 and the ground 7, and is a means for opening and closing an electric circuit.

  Similarly, the second switch 102 is provided on the second connection line 9 that connects the rail 4 and the ground 7, and is a means for opening and closing an electric circuit.

  The first resistor 103 is connected to the first connection line 8 in series with the first switch 101, and the second resistor 104 is connected to the second connection line 9 in series with the second switch 102.

  Note that the resistance values of the first resistor 103 and the second resistor 104 are smaller than the resistance value of the ground resistor 5.

  The first voltage value measuring unit 105 is connected to the first connection line 8 in parallel with the first switch 101 and the first resistor 103, and calculates the ground voltage value (first ground voltage value) of the rail 4 in the first substation 1. It is a device and means for measuring.

  The second voltage value measuring unit 106 is connected to the second connection line 9 in parallel with the second switch 102 and the second resistor 104, and calculates the ground voltage value (second ground voltage value) of the rail 4 in the second substation 2. It is a device and means for measuring.

  The first current value measuring unit 107 detects the ground fault current flowing from the ground 7 to the first substation 1 via the first connection line 8 when a failure (high resistance ground fault) occurs in the feeder 3. This is a device or means for measuring a value (first current value).

The first current value I ₁ measured by the first current value measuring unit 107 is expressed by the following mathematical formula (5).

The second current value measuring unit 108 is a value of a ground fault current (second current value) that flows into the second substation 2 from the ground 7 through the second connection line 9 when a failure occurs in the feeder 3. It is a device and means for measuring.

The second current value I ₂ measured by the second current value measuring unit 108 is expressed by the following mathematical formula (6).

Equation (5), in equation (6), E wear electrostatic voltage, the resistance value of Re is the resistance 103 and 104, _{R f} is fault point resistance, R _[rho is simplified combined resistance of the ground resistance, _{R s} rectifier internal resistance And the combined resistance of the power source impedance, R _t feeder wire resistance, and d represents the failure point section length ratio. As shown in FIGS. 2 and 3, σR is a combined resistance of the rectifier internal resistance and the power source impedance R _{s and the} wire resistance R _t .

The coefficient K is K = 1 when the switches 103 and 104 are closed (7)
When the switches 103 and 104 are open, K = ∞ (8)
It becomes.

  Next, the configuration of the DC feeder protection relay device 200 will be described. FIG. 4 is a block diagram showing the configuration of the DC feeding protection relay device according to the present embodiment.

  The DC feeder protection relay device 200 includes an input converter 201, an analog filter 202, an AD converter 203, and a calculation unit 204.

  The input converter 201 is connected to the first voltage value measuring unit 105, the second voltage value measuring unit 106, the first current value measuring unit 107, the second current value measuring unit 108, and the analog filter 202.

  The input converter 201 is measured by the first ground voltage value measured by the first voltage value measuring unit 105, the second ground voltage value measured by the second voltage value measuring unit 106, and the first current value measuring unit 107. The second current value measured by the first current value and second current value measurement unit 108 is acquired and output to the analog filter 202.

  The analog filter 202 is connected to the input converter 201 and the AD converter 203, removes noise and harmonic components of the ground voltage value and current value acquired from the input converter 201, and outputs to the AD converter 203. It is.

  The AD converter 203 is a processing unit that is connected to the analog filter 202 and the calculation unit 204, digitizes the ground voltage value and current value of the analog data acquired from the analog filter 202, and outputs the digitized value to the calculation unit 204.

  Next, the structure of the calculating part 204 is demonstrated using FIG. FIG. 5 is a block diagram showing a configuration of a calculation unit of the DC feeding protective relay device according to the present embodiment.

  The calculation unit 204 includes a first voltage value acquisition unit 301, a second voltage value acquisition unit 302, a first voltage value determination unit 303, a second voltage value determination unit 304, a first signal output unit 305, and a second signal output unit 306. , A first current value acquisition unit 307, a second current value acquisition unit 308, a total current value calculation unit 309, a change amount calculation unit 310, a change amount determination unit 311, and a trip command output unit 312.

  The first voltage value acquisition unit 301 is a processing unit that acquires the first ground voltage value digitized by the AD converter 203 at regular intervals.

  The second voltage value acquisition unit 302 is a processing unit that acquires the second ground voltage value digitized by the AD converter 203 at regular intervals.

  The first voltage value determination unit 303 is a processing unit that determines whether or not the first ground voltage value acquired by the first voltage value acquisition unit 301 is equal to or greater than a predetermined threshold value (voltage threshold value).

  The second voltage value determination unit 304 is a processing unit that determines whether or not the second ground voltage value acquired by the second voltage value acquisition unit 302 is greater than or equal to a voltage threshold value.

  The first signal output unit 305 is a processing unit that outputs a signal for closing the first switch 101 when the first voltage value determination unit 303 determines that the first ground voltage is equal to or higher than the voltage threshold.

  The second signal output unit 306 is a processing unit that outputs a signal for closing the second switch 102 when the second voltage value determination unit 304 determines that the second ground voltage is equal to or higher than the voltage threshold.

The first current value acquisition unit 307 is a processing unit that acquires the first current value I ₁ digitized by the AD converter 203 at regular intervals.

The second current value acquisition unit 308 is a processing unit that acquires the second current value I ₂ digitized by the AD converter 203 at regular intervals.

The total current value calculation unit 309 is a total value I of the first current value I ₁ and the second current value I ₂ acquired at regular intervals by the first current value acquisition unit 307 and the second current value acquisition unit 308. It is a processing unit for calculating the _total . Specifically, it is calculated by the following mathematical formula (9).

I _total = I ₁ + I ₂ (9)
The change amount calculation unit 310 is a processing unit that calculates a change amount ΔI _total of the total value I _total calculated by the total current value calculation unit 309 per predetermined time t. Specifically, the change amount ΔI _total is calculated by the following mathematical formula (10).

In Equation (10), I ′ _total is calculated from the first current value I ₁ and the second current value I ₂ acquired by the first current value acquisition unit 307 and the second current value acquisition unit 308 before the predetermined time t. It is the sum total value. The predetermined time t can be arbitrarily set.

The change amount determination unit 311 is a processing unit that determines whether or not the change amount ΔI _total calculated by the change amount calculation unit 310 is equal to or greater than a predetermined threshold (change amount threshold).

The trip command output unit 312 is a processing unit that outputs a trip command for opening the feeder circuit breakers 12 and 22 when the change amount determination unit 311 determines that the change amount ΔI _total is equal to or greater than the change amount threshold value.

  The trip command output unit 312 may be configured to output a trip command for opening a switch that replaces the feeder circuit breaker 12.

  Next, the operation of the DC feeding protective relay device 200 will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of the DC feeding protective relay device according to the present embodiment. In FIG. 6, when a ground fault in the feeder 3 occurs, the DC feeder protection relay device 200 acquires the first ground voltage value and the second voltage value and outputs a signal for closing the switches 101 and 102. Shows the operation.

  The input converter 201 acquires the first ground voltage value measured by the first voltage value measuring unit 105 and the second ground voltage value measured by the second voltage value measuring unit 106 and outputs them to the analog filter 202. (S401).

  The analog filter 202 removes noise and harmonic components of the ground voltage value acquired from the input converter 201, and outputs them to the AD converter 203 (S402).

  The AD converter 203 digitizes the ground voltage value of the analog data acquired from the analog filter 202 and outputs the digitized voltage value to the calculation unit 204 (S403).

  The arithmetic unit 204 acquires the digitized ground voltage value from the AD converter 103, and outputs a signal for closing the switches 101 and 102 when the condition is satisfied (S404).

  Next, the operation of the arithmetic unit 204 will be described in detail with reference to FIGS. 7 and 8 are flowcharts showing the operation of the arithmetic unit of the DC feeding protective relay device according to the present embodiment.

  FIG. 7 shows an operation of acquiring a first ground voltage value from the AD converter 103 and outputting a signal for closing the switch 101.

  The first voltage value acquisition unit 301 acquires the first ground voltage value digitized by the AD converter 203 at regular intervals (S501).

  The first voltage value determination unit 303 determines whether or not the first ground voltage value acquired by the first voltage value acquisition unit 301 is greater than or equal to the voltage threshold (S502).

  The first signal output unit 305 outputs a signal for closing the first switch 101 when the first voltage value determination unit 303 determines that the first ground voltage is equal to or higher than the voltage threshold (YES in S502) (S503).

  When the first voltage value determination unit 303 does not determine that the first ground voltage is equal to or higher than the voltage threshold (NO in S502), it means that no failure has occurred, and thus no signal is output.

  FIG. 8 shows an operation of acquiring a second ground voltage value from the AD converter 103 and outputting a signal for closing the switch 102.

  The second voltage value acquisition unit 302 acquires the second ground voltage value digitized by the AD converter 203 at regular intervals (S601).

  The second voltage value determination unit 304 determines whether or not the second ground voltage value acquired by the second voltage value acquisition unit 302 is greater than or equal to the voltage threshold (S602).

  The second signal output unit 306 outputs a signal for closing the second switch 102 when the second voltage value determination unit 304 determines that the second ground voltage is equal to or higher than the voltage threshold (YES in S602) (S603).

  When the second voltage value determination unit 304 does not determine that the second ground voltage is equal to or higher than the voltage threshold (NO in S602), it means that no failure has occurred, and thus no signal is output.

  When signals are output from the first signal output unit 305 and the second signal output unit 306, the first switch 101 and the second switch are closed.

  Since the first resistor 103 has a resistance value smaller than that of the ground resistor 5, the ground fault current flows from the ground 7 to the first substation 1 through the first connection line 8 when the first switch 101 is closed. .

  Similarly, since the resistance value of the second resistor 104 is smaller than that of the ground resistor 5, when the second switch 102 is closed, the ground fault current flows from the ground 7 through the second connection line 9 to the second substation 2. Flow into.

  FIG. 9 is a flowchart showing the operation of the DC feeding protection relay device according to the present embodiment. FIG. 9 shows an operation until the DC feeder protection relay device 200 acquires the first current value and the second current value and outputs a trip command.

  The input converter 201 acquires the first current value measured by the first current value measuring unit 107 and the second current value measured by the second current value measuring unit 108, and outputs them to the analog filter 202 (S701). .

  The analog filter 202 removes noise and harmonic components of the current value acquired from the input converter 201 and outputs them to the AD converter 203 (S702).

  The AD converter 203 digitizes the current value of the analog data acquired from the analog filter 202 and outputs it to the arithmetic unit 204 (S703).

  The arithmetic unit 204 acquires the digitized current value from the AD converter 103, and outputs a trip command to open the power circuit breakers 12 and 22 when the condition is satisfied (S704).

  Next, the operation of the arithmetic unit 204 will be described in detail with reference to FIG. FIG. 10 is a flowchart showing the operation of the calculation unit of the DC feeding protective relay device according to the present embodiment.

  The first current value acquisition unit 307 acquires the first current value digitized by the AD converter 203 at regular intervals, and the second current value acquisition unit 308 acquires the second current value digitized by the AD converter 203. Current values are acquired at regular intervals (S801).

  The total current value calculation unit 309 calculates the total value of the first current value and the second current value (S802).

  The change amount calculation unit 310 calculates the change amount per predetermined time of the total value calculated by the total current value calculation unit 309 (S803).

  The change amount determination unit 311 determines whether or not the change amount calculated by the change amount calculation unit 310 is greater than or equal to the change amount threshold value (S804).

  The trip command output unit 312 outputs a trip command to open the feeder circuit breakers 12 and 22 when the variation determination unit 311 determines that the variation is equal to or greater than the variation threshold (YES in S804) (S805). .

  When the change amount determination unit 311 does not determine that the change amount is equal to or greater than the change amount threshold value (NO in S804), the trip command is not output.

In this embodiment, since the rail 4 is grounded by the high-resistance grounding resistor 5, the values of the simple combined resistance R _ρ of the grounding resistance are the fault point resistance R _f , feeder resistance R _t , rectifier internal resistance, and power source impedance The combined resistance R _t , R _s and R _t is very large compared to the combined resistance σR.

  Therefore, from the above-described mathematical formulas (5) and (6), when the switches 101 and 102 are open, the current value flowing from the ground into the substations 1 and 2 via the ground line 6 is very small.

On the other hand, when the DC feeder protection relay device 200 of the present embodiment is operated, when the switches 101 and 102 are closed, the grounding in the equations (5) and (6) is compared with the case where the switches 101 and 102 are open. The effect of the simple combined resistance _Rρ of the resistance is reduced. As a result, the current value increases.

  As a result, it becomes possible to distinguish between the ground fault current and the electric vehicle load current (running current of the electric car), and a high resistance ground fault can be detected appropriately. By appropriately detecting a high-resistance ground fault and opening only the feeder circuit breaker in the failure section, it is possible to prevent the occurrence of a power outage section over a wide area.

  This embodiment is presented as an example and is not intended to limit the scope of the invention. The present embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the invention described in the claims and equivalents thereof as well as included in the scope and spirit of the invention.

DESCRIPTION OF SYMBOLS 1 ... 1st substation 2 ... 2nd substation 3 ... Feed wire 4 ... Rail 5 ... Grounding resistance 6 ... Ground wire 7 ... Ground 8 ... 1st connection wire 9 ... 2nd connection wire 11, 21 ... Rectifier 12,22 ... feeder circuit breaker 100 ... DC feeder protection control system 101 ... first switch 102 ... second switch 103 ... first resistor 104 ... second resistor 105 ... first voltage value measuring unit 106 ... second voltage value measuring unit 107 ... first current value measuring unit 108 ... second current value measuring unit 200 ... DC feeding protective relay device 201 ... input converter 202 ... analog filter 203 ... AD converter 204 ... calculating unit 301 ... first voltage value acquiring unit 302 ... second voltage value acquisition unit 303 ... first voltage value determination unit 304 ... second voltage value determination unit 305 ... first signal output unit 306 ... second signal output unit 307 ... first current value acquisition unit 308 ... second Current value acquisition unit 309... Total current value calculation unit 310 Change amount calculation unit 311 ... change amount determining unit 312 ... trip command output unit

Claims (2)

In a DC feeder protection control system for protecting and controlling an electric system in which a first substation and a second substation each having a circuit breaker or a switch are installed,
A first switch provided on a first connection line for connecting the rail and the ground, and for opening and closing an electric circuit;
A second switch that opens and closes an electric circuit, provided on a second connection line that connects the ground and the ground grounded by a ground line to which a ground resistance is connected;
A first resistor connected in series with the first switch to the first connection line and having a resistance value smaller than the ground resistance;
A second resistor connected in series with the second switch to the second connection line and having a resistance value smaller than the ground resistance;
A first voltage value measuring unit connected to the first connection line in parallel with the first switch and the first resistor, and measuring a first ground voltage value of the rail in the first substation;
A second voltage value measuring unit connected to the second connection line in parallel with the second switch and the second resistor, and measuring a second ground voltage value of the rail in the second substation;
When the first ground voltage value measured by the first voltage value measuring unit is greater than or equal to a predetermined voltage threshold, a signal for closing the first switch is output and measured by the second voltage value measuring unit. A DC feeder protection relay device that outputs a signal for closing the second switch when the second ground voltage value is equal to or greater than the voltage threshold;
A first current value measuring unit for measuring a first current value flowing into the first substation from the first connection line;
A second current value measuring unit that measures a second current value flowing into the second substation from the second connection line,
The DC feeding protective relay device includes the circuit breaker based on the first current value measured by the first current value measuring unit and the second current value measured by the second current value measuring unit. Or the DC feeding system protection control system which determines whether the said switch is opened. The DC feeding protective relay device is
A first voltage value acquisition unit that acquires the first ground voltage value measured by the first voltage value measurement unit;
A second voltage value acquisition unit for acquiring the second ground voltage value measured by the second voltage value measurement unit;
A first voltage value determination unit that determines whether or not the first ground voltage value acquired by the first voltage value acquisition unit is equal to or greater than the voltage threshold;
A second voltage value determination unit that determines whether or not the second ground voltage value acquired by the second voltage value acquisition unit is equal to or greater than the voltage threshold;
A first signal output unit configured to output a signal for closing the first switch when the first voltage value determination unit determines that the first ground voltage value is equal to or greater than the voltage threshold;
A second signal output unit for outputting a signal for closing the second switch when the second voltage value determination unit determines that the second ground voltage value is equal to or greater than the voltage threshold;
A first current value acquisition unit that acquires the first current value measured by the first current value measurement unit;
A second current value acquisition unit that acquires the second current value measured by the second current value measurement unit; the first current value acquired by the first current value acquisition unit; and the second current value acquisition A total current value calculation unit for calculating a total value with the second current value acquired by the unit;
A change amount calculating unit for calculating a change amount per predetermined time of the total value calculated by the total current value calculating unit;
A change amount determination unit that determines whether or not the change amount calculated by the change amount calculation unit is equal to or greater than a predetermined change amount threshold;
The trip command output unit that outputs a trip command to open the circuit breaker or the switch when the change amount is determined by the change amount determination unit to be equal to or greater than the change amount threshold value. DC feeding system protection control system.

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