JP2017017922A - Dc power supply system, and dc ground fault point examination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power supply system and a DC ground fault point examination method, capable of identifying a ground fault point using a simple structure and a method.SOLUTION: A DC power supply system 10 includes: a DC power supply 3; a DC power supply circuit 4, connected between a P line 2P and an N line 2N, for distributing and supplying the DC power supply 3; a DC ground fault detector 5, connected between the P line 2P and the N line 2N, for detecting a ground fault generated at the supply destination of the DC power supply 3; and a pseudo ground fault current supply circuit 11, connected between a bus 2 (each of the P line 2P and the N line 2N) and the earth, for making the electric conduction of a pseudo ground fault current at the point in which the ground fault occurs.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a DC power supply system and a DC ground fault investigation method that make it easier to identify a DC ground fault location.

  In power facilities such as power plants and substations, a DC power source that is more resistant to dielectrics than an AC power source is mainly used as a power source for device control.

  FIG. 6 shows a configuration example of a DC power supply system 1 constructed in a power system (hereinafter referred to as “DC power system”) in a facility where a conventional DC power source is used in a power facility such as a power plant. It is the schematic which showed.

  The DC power supply system 1 includes, for example, a bus 2, that is, a positive electrode side bus (P line) 2 P connected to the positive electrode (P pole) of the DC power source 3 and a negative electrode connected to the negative electrode (N pole) of the DC power source 3. A DC power supply circuit 4 that distributes and supplies a DC power supply 3 and a DC ground fault detector 5 that detects a ground fault are connected to a side bus (N line) 2N.

  The DC power source 3 is connected to the positive side bus (P line) 2P on the positive side and the negative side bus (N line) 2N on the negative side, and supplies DC power to the equipment connected to the bus 2.

  The DC power supply circuit 4 supplies DC power to devices connected downstream via a plurality of feeders (feeding lines) 6 connected to the bus 2 (between the positive-side bus 2P and the negative-side bus 2N). Circuit.

  The DC ground fault detector 5 is a device that detects a ground fault generated in a device connected to the bus 2 via the feeder 6 and has one end on the bus 2 (positive side bus 2P and negative side bus 2N) side. The other end is connected (grounded) to the ground.

  In the DC power supply system 1 configured as described above, when a ground fault (DC ground fault) occurs on the downstream side of the plurality of feeders 6, the location where the ground fault occurs is positive by the DC ground fault detector 5. Whether it is on the (P pole) side or the negative electrode (N pole) side can be detected. However, in the DC power supply system, even if the DC ground fault detector 5 can identify the pole where the ground fault occurs, it cannot identify which feeder 6 is causing the fault.

  Therefore, the DC power supply system may be provided with a DC leakage device 7 that detects a ground fault in units of the feeder 6 for the purpose of facilitating identification of a ground fault occurrence location. However, even in a DC power supply system in which the DC leakage device 7 is installed, what can be specified by the DC leakage device 7 is only the feeder 6 in which the ground fault has occurred, and the location where the ground fault occurs is limited to the unit of the feeder 6. However, it cannot be specified in units of circuits (supply destinations) further branched from the feeder 6.

  Therefore, regardless of whether or not the DC leakage device 7 is installed, in order to finally identify the ground fault occurrence location, the DC power supply of the feeder 6 in which the ground fault is detected is stopped (power failure) The DC power supply circuit 4 needs to be investigated individually, that is, for each circuit (supply destination) further branched from the feeder 6.

  In addition, when a power failure of the control power supply is necessary, the plant must be stopped, and the influence is enormous. From the viewpoint of surely preventing the influence of the ground fault of the equipment from causing a serious situation such as the suspension of operation of the power facility, the power supply path in the DC power supply system is made redundant and the first power supply path used in normal times And a second power supply path used when detecting a ground fault, and when a ground fault is detected in the first power supply path, the power supply path used for power supply is changed from the first power supply path to the second power supply path. A DC power supply system that can be switched to is proposed (for example, Patent Document 1).

JP 2003-61239 A

  However, in the conventional DC power supply system such as Patent Document 1 described above, the influence of the ground fault of the device does not cause a serious situation such as the suspension of operation of the power facility, but the required power supply path increases. Since the system becomes large-scale, there is a problem that the occupation range of the constituent devices is increased and the cost is increased.

  The present invention has been made in consideration of the above-described circumstances, and a DC power supply system capable of specifying a ground fault location without stopping (power failure) the supply of DC power by a simpler configuration and method than conventional ones. And it aims at providing a direct current ground fault investigation method.

  In order to solve the above-described problem, a DC power supply system according to an embodiment of the present invention is connected between a DC power supply and a positive-side bus and a negative-side bus to which the DC power is connected. A DC power supply circuit for distributing and supplying, a DC ground fault detecting means for detecting a ground fault occurring at a supply destination of the DC power source, and a positive side bus and a negative side bus connected to the DC power source And a ground fault current supply means for supplying a ground fault current to a location where a ground fault has occurred.

  In order to solve the above-described problem, a DC ground fault investigation method according to an embodiment of the present invention is connected between a positive-side bus and a negative-side bus to which a DC power is connected, and distributes the DC power. The location of the occurrence of a ground fault in the DC power supply destination of a DC power supply system comprising a DC power supply circuit to be supplied and a DC ground fault detection means for detecting a ground fault generated in the DC power supply destination When the DC ground fault detection means detects a ground fault at one of the positive electrode side and the negative electrode side, a simulated ground fault current is generated at the location where the ground fault has occurred. Connecting a simulated ground fault current supply means to be energized between a bus on the pole side different from the pole where the DC ground fault detection means has detected a ground fault and the ground, and the DC ground fault detection means detecting a ground fault. By grounding the bus on the pole side that is different from the pole A step of energizing a simulated ground fault current at a place where a fault has occurred, a current of energizing the supply destination of the DC power supply, and a supply destination of the DC power source through which the simulated ground fault current flows And a step of specifying.

  According to the present invention, a ground fault location can be identified by a simpler configuration and method than before without stopping the supply of DC power (power failure).

1 is a schematic diagram showing a configuration example (first configuration example) of a DC power supply system according to an embodiment of the present invention. Schematic which showed the structural example (2nd structural example) of the direct-current power supply system which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing explaining the principle which identifies the ground fault generation | occurrence | production location in the DC power supply system which concerns on embodiment of this invention, (A) is explanatory drawing which shows the state before DC ground fault location investigation at the time of N pole ground fault occurrence (B) is explanatory drawing which shows the state at the time of a direct-current ground fault location investigation. Explanatory drawing explaining the step which specifies the feeder in which the ground fault generate | occur | produced in the direct-current ground fault location investigation method which concerns on embodiment of this invention. It is explanatory drawing explaining the step which specifies the circuit which the ground fault generate | occur | produced of the direct-current ground fault location investigation method which concerns on embodiment of this invention, (A) is the schematic which shows a 1st step, (B) is 2nd. Schematic which shows a step, (C) is the schematic which shows a 3rd step. Schematic which showed the example of a structure of the conventional DC power supply system.

  Hereinafter, a DC power supply system and a DC ground fault investigation method according to embodiments of the present invention will be described with reference to the drawings. In the following description of the present embodiment, constituent elements that are substantially the same as the constituent elements of the DC power supply system 1 illustrated in the figure are given the same reference numerals, and redundant descriptions are omitted.

  FIG. 1 is a schematic diagram illustrating a first configuration example of a DC power supply system 10 that is an example of a DC power supply system according to an embodiment of the present invention. FIG. 2 is a second configuration of the DC power supply system 10. It is the schematic which showed the example.

  The DC power supply system 10 (FIGS. 1 and 2) includes, for example, a DC power supply 3, a DC power supply circuit 4, a DC ground fault detector 5 as a DC ground fault detection means, and a simulated ground fault current supply means. And a simulated ground fault current supply circuit 11 (11P, 11N). A plurality of feeders (feeding lines) 6 are connected to the bus 2 (between the positive side bus 2P and the negative side bus 2N) to which the DC power supply 3, the DC power supply circuit 4, and the DC ground fault detector 5 are connected. Power is supplied to devices connected to the downstream side via the feeder 6.

The DC ground fault detector 5 is connected to the positive side bus (P line) 2P, which is the bus 2 to which the positive side of the DC power source 3 is connected, or is connected to the negative side of the DC power source 3. It is detected whether or not a DC ground fault (N-pole grounding) has occurred on the negative-side bus (N line) 2N side that is the bus 2 to be connected. The DC ground fault detector 5 includes, for example, a positive side bus (P line) 2P which is a positive side bus 2 and a resistance element (for example, resistance value R ₂ ) 5P connected between the ground and a negative side bus 2 And a resistance element (for example, resistance value R ₂ ) 5N connected between the negative electrode bus (N line) 2N and the ground.

  The simulated ground fault current supply circuit 11 (11P, 11N) includes a first simulated ground fault current supply circuit 11P for forcibly grounding the positive side bus (P line) 2P and a negative side bus (N line) 2N. And a second simulated ground fault current supply circuit 11N that forcibly causes a ground fault. Both the simulated ground fault current supply circuits 11P and 11N have substantially the same circuit configuration.

The first simulated ground fault current supply circuit 11P is, for example, connected in series with a switch 21 that opens and closes an electric circuit, a fuse 22 that is connected in series with the switch 21, and that interrupts an overcurrent of the electric circuit, and a fuse 22. the resistance value _{R 1} predetermined range (e.g., 0.5Keiomega～1.5Keiomega) comprises a variable resistor 23 can be varied within the switch 21 is positive-side bus 2P, the variable resistor 23 is ground (ground terminal ) Connected (grounded).

  Here, the capacity of the fuse 22 is determined in consideration of the relationship with the system connected via the bus 2, and the simulated ground fault current supply circuit 11 (11P, 11N), for example, is simulated. It is set so that a current (500 mA in this example) exceeding about 5 times the estimated value of the ground fault current (in this example, about 100 mA at the maximum) can be cut off. In addition, it can be determined in consideration of the current interruption function of the feeder 6.

The first simulated ground fault current supply circuit 11P closes the switch 21 to forcibly cause the positive bus (P line) 2P to ground, thereby simulating a ground fault current (for example, 10 mA to 100 mA). Degree). The first simulated ground fault current supply circuit 11P, by changing the resistance value R ₁ of the variable resistor 23, it is possible to change the size of the simulated ground fault current.

  The range of the magnitude of the simulated ground fault current is defined by two conditions. The first condition for defining the upper limit is that the feeder 6 is of a size that does not cut off the current. A second condition for defining the lower limit of the simulated ground fault current is that the simulated ground fault current can be captured by a current measuring device such as the DC clamp meter 30 (FIGS. 4 and 5).

  In DC power supply systems installed in many power plants, the current value at which the feeder 6 cuts off the current is over 100 mA, and if the magnitude of the simulated ground fault current is about 100 mA or less, the first The condition can be cleared.

  Further, by supplying a simulated ground fault current, when the current flowing from the ground fault location energizes the feeder 6, the magnitude is about 10 mA (change in current before and after the supply of the simulated ground fault current). If so, the simulation ground fault current can be sufficiently captured. For example, the measurement range is about 0 mA to 100 mA, and the resolution (minimum display unit for digital, 1/10 of the minimum scale for analog) is 1 mA. If so, a simulated ground fault current can be sufficiently captured.

The second simulated ground fault current supply circuit 11N includes, for example, a switch 21, a fuse 22, and a variable resistor 23. The switch 21 is connected to the negative bus 2N, and the variable resistor 23 is connected to the ground (grounding terminal). ) Connected (grounded). The second simulated ground fault current supply circuit 11N closes the switch 21, thereby forcibly grounding the negative side bus (N line) 2N and generating a simulated ground fault current. Further, by changing the resistance value R ₁ of the variable resistor 23, it is possible to change the size of the simulated ground fault current.

  In the DC power supply system 10 described above, the simulated ground fault current supply circuit 11 may be configured to be detachable from the connected bus 2 or the ground. The simulated ground fault current supply circuit 11 is only required to be connected between the buses 2P and 2N and the ground at least when investigating the place where the ground fault occurs, and is not necessarily connected in other cases. Is not required.

  Moreover, the DC power supply system 10 described above is an example in which a simulated ground fault current supply circuit 11 including a first simulated ground fault current supply circuit 11P and a second simulated ground fault current supply circuit 11N is provided. However, when the simulated ground fault current supply circuit 11 is configured to be detachable, for example, the DC power supply system 10 illustrated in FIG. 1 as in the DC power supply system 10 illustrated in FIG. It is good also as a structure provided with the simulated ground fault current supply circuit 11 which abbreviate | omitted any one of the 1st simulated ground fault current supply circuit 11P and the 2nd simulated ground fault current supply circuit 11N.

  Further, the above-described simulated ground fault current supply circuit 11 includes, as an example, a switch 21, a fuse 22, and a variable resistor 23. However, from the technical viewpoint, the fuse 22 is not necessarily provided. It may be omitted.

  Further, in the simulated ground fault current supply circuit 11, instead of the variable resistor 23, a normal resistor whose resistance value cannot be varied may be employed. Even in this case, the simulated ground fault current supply circuit 11 can generate a simulated ground fault current (although it cannot be changed).

  Next, as an example of the DC ground fault location investigation method according to the embodiment of the present invention, a ground fault occurrence location survey method in the DC power supply system 10 configured as described above will be described.

  FIG. 3 is an explanatory diagram for explaining the principle of identifying a ground fault occurrence location in the DC power supply system 10. FIG. 3 (A) shows a state before the DC ground fault location investigation when the N pole ground fault occurs (the switch 21 is opened). ), And FIG. 3B is an explanatory diagram showing a state when the DC ground fault location is investigated (the switch 21 is closed).

In the DC power supply system 10, when no DC ground fault occurs, the ground fault current I ₃ shown in FIGS. 3A and 3B does not occur, so the current on the positive electrode (P pole) side The value of the current I ₂ on the negative electrode (N pole) side is the same as I ₁ . That is, the ground fault current I ₃ = 0, and the current I ₁ on the positive electrode (P pole) side = the current I ₂ on the negative electrode (N pole) side. Note that the switch 21 is open during normal system operation, such as when a DC ground fault has not occurred (except when investigating the DC ground fault location).

When a ground fault occurs at the negative electrode (N pole), that is, when an N pole ground fault occurs (FIG. 3A), a ground fault current I ₃ (> 0) leaks from the ground fault occurrence point to the ground. A ground fault current I ₃ (> 0) flows through the resistance element 5P of the DC ground fault detector 5. The DC ground fault detector 5 detects the occurrence of the N-pole ground fault by detecting that the ground fault current I ₃ has flowed through the resistance element 5P. When the N pole ground fault occurs, the current I ₂ on the N pole side is larger than the current I ₁ on the P pole side by the amount of the ground fault current I ₃ .

In the DC power supply system 10, the investigation of the DC ground fault location is performed first by checking whether the simulated ground fault current supply circuit 11 is connected to a pole different from the pole where the DC ground fault detector 5 detects the ground fault. The simulated ground fault current (simulated ground fault current I ₄ ) is operated by operating the simulated ground fault current supply circuit 11 connected to the pole different from the pole where the DC ground fault detector 5 detects the ground fault. Supply to the ground.

Here, in the case illustrated in FIG. 2, the simulated ground fault current supply circuit 11 is detachable, and the simulated ground fault current supply circuit 11 is connected to a pole different from the pole where the DC ground fault detector 5 has detected the ground fault. Is not connected, the simulated ground fault current supply circuit 11 is connected to a pole different from the pole where the DC ground fault detector 5 detects the ground fault, and then the simulated ground fault current supply circuit 11 is operated. supplying a simulated ground fault current I ₄ to ground Te.

In the DC power supply system 10, for example, when the DC ground fault detector 5 detects an N-pole ground fault, it is provided for the simulated ground fault current supply circuit 11 (11P) connected to the positive-side bus (P line) 2P. The closed switch 21 is closed and the positive side bus (P line) 2P and the ground are short-circuited (ground fault), so that the simulated ground fault current I ₄ flows from the positive side bus (P line) 2P toward the ground ( FIG. 3 (B)).

When the positive side bus (P line) 2P is grounded, the simulated ground fault current I ₄ flowing to the ground enters the circuit that is mostly grounded from the ground and enters the negative side bus (N line) 2N. Inflow. Accordingly, the current I ₂ on the N pole side after supplying (energizing) the simulated ground fault current I ₄ to the ground fault occurrence location flows in at least a part of the simulated ground fault current I _4. to increase than the previous supply of I _4.

In the DC power supply system 10, the simulated ground fault current I ₄ can flow toward the ground. By flowing the simulated ground fault current I ₄ toward the ground, most of the simulated ground fault current I ₄ is grounded. to flowing from絡発production point bus 2 (2P, 2N) in a system that is connected to, if identified the destination of the DC power supply 3 which is simulated ground fault current I ₄ flows, identifying the land絡発production locations Can do.

If there is only one ground fault location, the simulated ground fault current I ₄ entering from the location has almost the same current value as the simulated ground fault current I ₄ flowing to the ground. In this case, since most of the simulated ground fault current I ₄ flowing to the ground is shunted to the various fault locations, the amount of the simulated ground fault current flowing into each fault location becomes small, and the simulated ground fault is generated. There may be a case where the change in the current value before and after the supply of the current I ₄ is difficult to understand.

In such a case, by adjusting the resistance value of the variable resistor 23, increasing the amount of simulated ground fault current I ₄ flowing into the ground, a large change in the current value before and after the supply of the simulated ground fault current I ₄ can do. Therefore, the DC power supply power supply system 10, by adjusting the resistance value of the variable resistor 23, as the earth絡箇plant occurs in a plurality of locations at the same time, capturing the change in the current value before and after the supply of the simulated ground fault current I ₄ It is possible to identify the locations related to each place.

  As described above, in the ground fault occurrence location investigation method in the DC power supply system 10, first, the DC ground fault detector 5 detects a ground fault at either the positive electrode (P pole) side or the negative electrode (N pole) side. When detected, a simulated ground fault current supply circuit 11 as a simulated ground fault current supply means is connected between the bus 2 on the pole side different from the pole where the DC ground fault detector 5 detects the ground fault and the ground. If the simulated ground fault current supply circuit 11 is connected, the switch 21 provided in the simulated ground fault current supply circuit 11 is closed, and the DC ground fault detector 5 detects the ground fault. Forcibly grounding the bus 2 on the pole side different from the pole.

Due to the forced ground fault, a simulated ground fault current I ₄ flowing toward the ground is energized to the location where the ground fault occurs. After clamping (pinch) both the P and N poles of the feeder 6 using a current measuring device (for example, the minimum measurement unit is about 10 mA) such as the DC clamp meter 30 (FIGS. 4 and 5), the ground fault The simulated ground fault current I ₄ is energized at the location where the fault occurs, and the change in current before and after the simulated ground fault current I ₄ is energized is confirmed to capture the simulated ground fault current I ₄ . Circuit simulated ground fault current I ₄ is energized (supply destination) is a portion generated ground fault.

The land絡発production location searching method in the DC power supply power supply system 10, the circuit simulation ground fault current I ₄ is energized (supply destination), i.e., to identify the circuit ground fault has occurred (supply destination), first, the simulated By identifying the feeder 6 through which the ground fault current I ₄ is energized, the feeder 6 in which the ground fault has occurred is identified, and then the branch line 8 branched from the feeder 6 through which the simulated ground fault current I ₄ is energized is identified. By doing so, the circuit (supply destination) in which the ground fault has occurred is specified.

  FIG. 4 is an explanatory diagram for explaining a step of identifying a feeder in which a ground fault has occurred in the DC ground fault investigation method according to the embodiment of the present invention.

For example, when the DC ground fault detector 5 detects the occurrence of a ground fault at the negative electrode (N pole), in the DC power supply system 10, first, a positive pole (P pole) that is a pole where no ground fault has occurred. A ground fault is caused between the grounds, and a simulated ground fault current I ₄ is supplied from the simulated ground fault current supply circuit 11 (11P). The size of the supplied simulated ground fault current I ₄ is different by the design specifications of the current measurement device of the DC clamp meter 30 or the like for use in capturing the feeder 6 and mock ground fault current I _4, for example, a 50~100mA The simulated ground fault current I ₄ is not interrupted by the feeder 6 and is set to a current value that is easy to capture.

A simulated ground fault current I ₄ is supplied from the simulated ground fault current supply circuit 11 (11P), and the presence or absence of a change (increase) in the measured value of the DC clamp meter 30 (FIGS. 4 and 5), which is an example of a current measuring device, is checked. Accordingly, identifying the feeder 6 which is simulated ground fault current I ₄ is flowed.

Whether the simulated ground fault current I ₄ is in the feeder 6 or not is determined based on the current of the feeder 6 on the side where the ground fault occurs with respect to the plurality of feeders 6 arranged in the DC power supply system 10. measured value, the simulated ground fault current I ₄ may be determined based on whether or not changes before and after feeding. The current is measured using a current measuring device such as a DC clamp meter 30, for example.

The simulated ground fault current I ₄ does not flow through the feeder 6 where no ground fault has occurred, while the feeder 6 where the ground fault has occurred is connected to the negative side bus (N line) 2N of the feeder 6. The electric wire (N line) on the side flows and the current value of the positive electrode side electric wire (P line) and the negative electrode side electric wire (N line) of the feeder 6 is unbalanced. Accordingly, the feeder 6 the increase in current value were confirmed to be equivalent to the simulated ground fault current I ₄ after supplying the simulated ground fault current I ₄ is circuit occurring ground fault (supply destination) is connected to a feeder 6 can be specified.

  In the DC power supply system 10, when a DC leakage device 7 that detects a ground fault in units of the feeder 6 is installed, a circuit (supply destination) in which a ground fault occurs using the DC leakage device 7 is provided. The connected feeder 6 may be specified.

  After identifying the feeder 6 to which the circuit (supply destination) in which the ground fault occurs is connected, it is subsequently determined whether or not a ground fault has occurred in each connection destination connected to the downstream side of the feeder 6. .

  FIG. 5 is an explanatory diagram for explaining a step of identifying a circuit in which a ground fault has occurred in the DC ground fault investigation method according to the embodiment of the present invention. FIG. FIG. 5B is a schematic diagram illustrating the specific third stage, FIG. 5B is a schematic diagram illustrating the specific second stage, and FIG. 5C is a schematic diagram illustrating the specific third stage.

  5 (FIG. 5 (A) to FIG. 5 (C)), the branch line 8 on the downstream side from the feeder 6 is mainly shown in FIG. 5 and shown in FIG. The upstream components from the feeder 6 such as the bus 2 and the DC power source 3 are not shown. 5B and 5C show the DC clamp meter 30 in a state where the main body portion is omitted (a state where the clamp portion 31 clamps a part of the branch line 8).

  Whether or not a ground fault has occurred is determined using, for example, a current measuring device such as a DC clamp meter 30, for example, branch line 8 (8P1, branching to k (k is a natural number of 2 or more)) supply destinations. 8N1; ...; 8Pk, 8Nk), a pair of positive side branch 8P (8P1, ..., 8Pk) and negative side branch 8N (8N1, ..., 8Nk) connected to the bus 2 and the supply destination (hereinafter, This is done by measuring the current flowing through the branch line pairs 8P (8P1,..., 8Pk), 8N (8N1,..., 8Nk).

  When a ground fault occurs at the DC power supply destination connected to the branch pair 8P, 8N, the current flowing through the branch pair 8P (8P1,..., 8Pk), 8N (8N1,..., 8Nk) is It changes before and after supplying a simulated ground fault current (energizing). Therefore, the supply destination of the DC power supply 3 causing the ground fault can be specified by specifying the branch line pairs 8P and 8N whose current values are changing.

  As a method for specifying the branch line pairs 8P and 8N whose current values are changing, for example, the branch line pairs 8P and 8N whose current values are not changing are stepwise excluded from all the branch line pairs 8P and 8N. There are several methods such as a method of narrowing down the branch line pairs 8P and 8N whose current values are changed (hereinafter referred to as “first method”) and a method of investigating the individual branch line pairs 8P and 8N. Can be considered.

  In the first method, for example, as shown in FIGS. 5A to 5C, branch line pairs 8P and 8N in which no change in current value occurs over a plurality of stages such as three stages are measured. The branch line pair 8P, 8N whose current value is changed finally is specified by excluding the target. In the first method, for example, the number of branch line pairs 8P and 8N to be measured per group is increased, and the number of branch line pairs 8P and 8N is narrowed down as the stage proceeds.

As the first stage (first current measurement) of the first technique, first, k pairs of branch lines 8P (8P1,..., 8Pk), 8N (8N1,..., 8Nk) are, for example, , divided into a plurality of groups, such as two groups for each group grouped, and supplies the simulated ground fault current I ₄ (energizing) to measure whether a change in the current value occurs before and after (FIG. 5 (A)).

  As a result of the current measurement at the first stage, it is usually divided into a group with current change “Yes” and a group with current change “No”. While remaining as a measurement target at the time of measurement, the group of current change “none” is excluded from the measurement target at the time of the next measurement (second stage).

  In the second stage, the same current measurement as in the first stage is performed on the group whose current change is “present” as a result of the current measurement at the previous (first stage) measurement.

That is, branch line pairs 8P and 8N belonging to the group in which the current change is “present” as a result of the first-stage current measurement are extracted, and the extracted branch line pairs 8P and 8N are further divided into a plurality of groups. For each divided group, it is measured whether or not a change in the current value occurs before and after the simulated ground fault current I ₄ is supplied (energized) (FIG. 5B). Then, the group with the current change “Yes” is left as the measurement target at the next (third stage) measurement, while the group with the current change “None” is the measurement target at the next (third stage) measurement. Exclude from

  In this way, in the second and subsequent stages, the same current measurement as in the first stage is performed for the group whose current change is “present” as a result of the current measurement at the previous measurement, and the current change “present” is determined. While the group is left as the measurement target at the next measurement, the group with the current change “none” is excluded from the measurement target at the next measurement.

  When the process of eliminating the branch pairs 8P and 8N with the current change “none” stepwise is repeated, if there is only one ground fault location, the branch pair 8P with the current change “present” is obtained. , 8N are identified as a pair (FIG. 5C).

  Although there may be a case where there are a plurality of ground fault locations, in this case, in any stage after the first stage, there may occur a case where all the groups become a group having a current change “present”. When all the groups become the groups having the current change “present”, all the branch line pairs 8P and 8N are set as measurement targets at the next measurement, and each group is divided into smaller groups and measured.

  Divide the measurement target into multiple groups, measure the current, leave the group with current change “Yes” as the measurement target at the next measurement, and measure the current change “None” group at the next measurement By repeating the exclusion from the target, finally, all the branch line pairs 8P and 8N to which the supply destination that does not cause the ground fault is connected (belonging to the group of “no change in current”) are excluded, Each of the branch line pairs 8P and 8N to which the supply destination in which the ground fault has occurred is connected (belonging to the group of “current change” “present”) can be specified.

  Thus, the DC ground fault location investigation method according to the embodiment of the present invention generates a simulated ground fault current on a pole different from the pole on which the ground fault occurs, for example, if the pole on which the ground fault occurs can be detected. By using the simulated ground fault current supply circuit 11 for supplying a simulated ground fault current to the ground fault location and a current measuring device such as the DC clamp meter 30, a circuit branching from the feeder 6 (a pair of branch lines) The ground fault location can be specified in units of 8P, 8N).

  Further, in the DC ground fault investigation method according to the embodiment of the present invention, the simulated ground fault current supply circuit 11 may be additionally provided after detecting the pole where the ground fault has occurred. 11 can be applied to a conventional DC power supply system such as the DC power supply system 1 (FIG. 6). Therefore, the DC ground fault investigation method according to the embodiment of the present invention can be widely applied to DC power supply systems having various configurations.

Furthermore, in the DC ground絡箇plants searching method according to an embodiment of the present invention, if the simulated grounding current supply circuit 11 comprises a variable resistor 23 capable of changing the resistance value R _1, by changing the resistance value R ₁ The magnitude of the simulated ground fault current I ₄ (FIGS. 3 and 4) can be adjusted, and even when a ground fault occurs at a plurality of locations, it is sufficient to detect changes before and after the simulated ground fault current I ₄ is supplied. A large-scale simulated ground fault current I ₄ can be supplied.

In the DC ground fault investigation method according to the embodiment of the present invention, the simulated ground fault current I ₄ (FIGS. 3 and 4) to be generated is about 10 to 100 mA, and is suppressed to about 100 mA at the maximum. , usually a change in current within a range in which the feeder 6 to allow a current (less than the current value interrupting the current), does not simulated ground fault current I ₄ is cut off. Further, the magnitude of the simulated ground fault current I _{4 is} as small as the feeder 6 allows energization, and even if the simulated ground fault current I ₄ flows into the DC power supply system including the DC power supply 3, there is an adverse effect. There is no effect. That is, the DC ground fault investigation method according to the embodiment of the present invention is a safe method that does not damage the DC power supply system including the DC power supply 3.

As described above, according to the DC power supply system 10 and the DC ground fault investigation method, when the DC ground fault detector 5 detects a pole having a ground fault, a pole different from the pole having the ground fault is forcibly set. By detecting a circuit (branch line pair 8P, 8N) on the downstream side of the feeder 6 where a simulated ground fault current I ₄ (FIGS. 3 and 4) is generated by causing a ground fault and the simulated ground fault current I ₄ is energized. Thus, the location where the ground fault occurs can be specified.

Further, in order to supply a simulated ground fault current (simulated ground fault current I ₄ ) to the location where the ground fault occurs, it is not necessary to provide a complicated electric circuit such as a redundant power supply path. A circuit having a simple configuration such as the current supply circuit 11 may be attached between the bus 2 (2P or 2N) of the pole different from the pole where the ground fault occurs and the ground, and the switch 21 may be closed. Regardless of whether it is redundant or not, it can be widely applied to conventional DC power supply systems such as the DC power supply system 1 (FIG. 6).

Further, when a simulated ground fault current is passed through the ground fault occurrence location, the generated ground fault current I ₄ (FIGS. 3 and 4) is about 10 to 100 mA, which is about 100 mA at the maximum, such as the DC clamp meter 30. Since the simulated ground fault current I ₄ is suppressed to a small amount that is less than the current value that the feeder 6 cuts off, the simulated ground fault current I ₄ Even if it flows into the DC power supply system that includes it, there is no adverse effect.

  Further, according to the DC power supply system 10 and the DC ground fault investigation method, the DC ground fault can be narrowed down without stopping (power failure) the supply of DC power. A ground fault location can be specified. Therefore, according to the DC power supply system 10 and the DC ground fault investigation method, it is possible to reliably prevent the influence of the ground fault of the equipment from causing a serious situation such as the suspension of operation of the power facility.

  Further, according to the DC power supply system 10 and the DC ground fault investigation method, since the simulated ground fault current supply circuit 11 includes the variable resistor 23, the amount of the simulated ground fault current can be changed. Even if a ground fault occurs at a plurality of locations, it is possible to identify each location fault by changing the amount of simulated ground fault current and measuring the current value.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be implemented in various forms other than the above-described examples in the implementation stage, and within the scope not departing from the gist of the invention. Various omissions, additions, replacements, and changes can be made. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 DC power system 2 Bus 2P Positive side bus (P line)
2N Negative side bus (N line)
3 DC Power Supply 4 DC Power Supply Circuit 5 DC Ground Fault Detector 6 Feeder 7 DC Leakage Device 10 DC Power Supply System 11 Simulated Ground Fault Current Supply Circuit 11P First Simulated Ground Fault Current Supply Circuit 11N Second Simulated Ground Fault Current Supply Circuit 21 Switch 22 Fuse 23 Variable resistor 24 Connection part

Claims (11)

DC power supply,
A DC power supply circuit connected between the positive-side bus and the negative-side bus to which the DC power is connected, and distributing and supplying the DC power;
DC ground fault detecting means for detecting a ground fault occurring at a supply destination of the DC power source;
Simulated ground fault current supply means connected between each of the positive and negative buses to which the DC power source is connected and the ground, and for supplying a simulated ground fault current to a place where a ground fault has occurred. DC power supply system characterized by that. The simulated ground fault current supply means includes a first simulated ground fault current supply circuit having one end connected to the positive-side bus and the other end grounded;
The DC power supply system according to claim 1, further comprising: a second simulated ground fault current supply circuit having one end connected to the negative-side bus and the other end grounded. The at least one of the first simulated ground fault current supply circuit and the second simulated ground fault current supply circuit is configured to be detachable from the connected bus. DC power supply system. The first simulated ground fault current supply circuit and the second simulated ground fault current supply circuit are respectively
A switch that opens and closes an electrical circuit, one end of which is connected to the bus;
The DC power supply system according to claim 2, further comprising: a resistance element having one end connected to the switch side and the other end grounded. The simulated ground fault current supply means includes
A detachable connection for both the positive side bus and the negative side bus,
A switch that is connected at one end to the connection part and opens and closes an electric circuit;
The DC power supply system according to claim 1, further comprising: a resistance element having one end connected to a side different from the connection portion side of the switch and the other end grounded. 6. The DC power supply system according to claim 4, wherein the resistance element is a variable resistance. A DC power supply circuit that is connected between a positive bus and a negative bus connected to a DC power supply, distributes and supplies the DC power, and a DC that detects a ground fault occurring at the DC power supply destination. It is a method of identifying the occurrence location of a ground fault occurring at the supply destination of the DC power supply of the DC power supply system comprising a ground fault detection means,
When the DC ground fault detection means detects a ground fault at one of the positive electrode side and the negative electrode side, a simulated ground fault current supply for supplying a simulated ground fault current to the location where the ground fault occurs Connecting a means between the ground and the bus on the pole side different from the pole where the DC ground fault detection means has detected a ground fault;
The DC ground fault detection means energizes a simulated ground fault current at the location where the ground fault has occurred by grounding a bus on the pole side different from the pole where the ground fault is detected;
Measuring a current flowing through the supply destination of the DC power supply, and specifying the supply destination of the DC power supply through which the simulated ground fault current flows through the DC power supply fault investigation, Method. The step of specifying the supply destination of the DC power source through which the simulated ground fault current flows is,
Identifying a feeder through which the simulated ground fault current flows among a plurality of feeders connected to each of the positive electrode side bus and the negative electrode side bus;
Using a current measuring device, branch lines branching from the identified feeder to the supply destination of the DC power source are paired on the positive electrode side and the negative electrode side, and the current flowing through the branch line is measured in pairs. Identifying the pair of branch lines whose current value has changed before and after applying the simulated ground fault current;
Supply destination of the DC power source through which the simulated ground fault current flows is defined as a supply destination of the DC power source connected to the pair of branch lines whose current value is changed before and after the simulation ground fault current is passed. The DC ground fault investigation method according to claim 7, further comprising a step of specifying as a destination. The feeder through which the simulated ground fault current flows is specified as follows:
When a leakage detection means is attached to each of the plurality of feeders connected to each of the positive-side bus and the negative-side bus, the result of the leakage detection by the leakage detection means and a current measuring device are used. Among the plurality of feeders, the current of the feeder in which the DC ground fault detection means detects the ground fault is measured, and the feeder whose current value is changed before and after the simulated ground fault current is energized is identified. Based on at least one of the results,
In the case where a leakage detecting means is not attached to each of the plurality of feeders connected to each of the positive side bus and the negative side bus, using the current measuring device, among the plurality of feeders, The DC ground fault detection means measures the current of the feeder that has detected the ground fault, and is performed based on the result of specifying the feeder whose current value has changed before and after applying the simulated ground fault current. The method for investigating a DC ground fault according to claim 8. The branch line pair is identified as follows:
It is performed by narrowing down the pairs of branch lines whose current values are changing before and after applying the simulated ground fault current by changing the logarithm for measuring the current a plurality of times. The method for investigating a DC ground fault according to claim 8, wherein: The narrowing of the pair of branch lines is as follows:
At the time of current measurement, all of the branch line pairs to be measured are divided into a plurality of groups, the current flowing through the branch line is measured for each group, and before and after the simulated ground fault current is applied. The method for investigating a DC ground fault according to claim 10, wherein the DC ground fault investigation method is performed by excluding a group whose current value has not changed from a measurement target for next current measurement.

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