JP2013009482A - Electricity distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electricity distribution system for safely supplying the power using a DC power from a DC power supply and an AC power from an AC power supply without increasing the size of the system, which reliably performs a leakage detection.SOLUTION: The electricity distribution system has single-phase three power feeding paths grounded by a neutral line and includes an AC distribution section that distributes an AC power from an AC power supply to a power feeding path and a DC distribution section that distributes a DC power from a DC power supply. The AC distribution section has a first leakage detection section that detects a leakage current in the AC power feeding path using a reference potential at the neutral line grounding. The DC distribution section has: an insulated DC-AC converting section that converts a DC current into an AC current; a middle point grounding section which is connected to the DC-AC converting section and has the grounding at a middle potential point in the DC power feeding path; and a second leakage detection section, which is connected to the DC-AC converting section or the middle point grounding section to detect a DC current leakage current in the DC power feeding path using the grounding middle point grounding section as the reference potential.

Description

  The present invention relates to a power distribution system that distributes AC power or DC power.

  Conventionally, as a power distribution system that distributes AC power and DC power in a building such as a house, a store, or an office building, for example, there is a grid interconnection system described in Patent Document 1. This grid-connected system converts DC power output from a DC power generation facility such as a photovoltaic power generation device for private power generation into AC power, and converts the converted AC power into a commercial power source ( System interconnection operation using an AC power system.

  Such a conventional grid interconnection system is a DC power generated by a DC power generation facility, converted into AC power using a power converter (power conditioner), and converted AC power and an AC power source. Coordinate commercial power sources. Furthermore, when the electric power exceeding the electric power consumed in the load is supplied from the DC power generation facility, the grid linkage system can reversely flow the surplus power to the commercial power source.

  Further, as a power distribution system for supplying DC power to a DC load device, for example, a power supply system described in Patent Document 2 has been proposed. This power supply system performs communication between a DC power supply unit and a terminal device of a DC load device. The power feeding control means compares the received power source information notified from the terminal device with the operating power source information held by the operating information storage means, and according to the comparison result, the voltage required for driving the DC load device and The output voltage is controlled so that current can be received.

  As the power source of the distribution system for distributing DC power to the DC load equipment, a plurality of power sources such as a solar power generation device and a DC power generation facility such as a fuel cell, a storage battery, and a commercial power source are used. It is necessary to construct a power distribution system that assumes the use of each power source. In this case, a configuration in which an output converter such as a DC / DC converter and an AC / DC converter is provided for each power source, and DC power of a predetermined voltage level is output from each output converter is general. Therefore, it is necessary to regularly and safely manage the installation and maintenance of each output converter for the power source of the power distribution system. In particular, the distribution board for distribution of DC power is different from the distribution panel for distribution of AC power, and it is necessary to install a large number of output converters such as DC / DC converters. For this reason, since heat is generated in the output converter, efficient distribution of heat is required in the distribution board for distribution of DC power.

  Moreover, in the grid connection system which distributes direct-current power and alternating current power like patent document 1, the alternating current input terminal from alternating current power sources, the direct current input terminal from direct current power sources, such as a solar cell, to a distribution board , And DC output terminals to be output to the DC load device are mixed. Leakage from each of these terminals or incorrect connection between the terminals can lead to not only damage to the equipment but also a serious accident.

  Therefore, Patent Document 3 proposes a power distribution system in which leakage current detection means is provided in either one of an AC distribution board or a DC distribution board.

JP 2003-284245 A JP 2009-159690 A JP 2009-178028 A

  However, in order to supply power safely using DC power from a DC power source and AC power from an AC power source, it is necessary to detect leakage in the DC power supply path and the AC power supply path with high accuracy. Furthermore, in order to manage the power distribution system safely, it is necessary to arrange the leakage detection means at many locations in the power distribution system. Therefore, there is a risk of increasing the size of the power distribution system.

  In particular, it is necessary to take a stable reference potential such as grounding in order to detect leakage in the DC power supply path and AC power supply path with high accuracy, but it is not possible to take the ground potential from the AC power supply during a power failure. There was a problem that it was difficult to set the ground potential.

  The present invention has been made in view of the above-described conventional circumstances, and safely supplies power using DC power from a DC power source and AC power from an AC power source without causing an increase in the size of the system. An object of the present invention is to provide a power distribution system that detects leakage in a power feeding path with high accuracy.

  The present invention is a power distribution system as described above, which has a single-phase three-wire power supply path grounded to a neutral line, an AC power distribution unit that distributes AC power from an AC power source to the power supply path, and DC power A DC distribution unit that distributes DC power from a power source, wherein the AC distribution unit detects a leakage current in a feeding path of the AC power using the neutral wire ground as a reference potential. 1, the DC power distribution unit is connected to the insulation type DC-AC conversion unit that converts DC to AC, and the DC-AC conversion unit, and the midpoint of the DC power supply path A midpoint grounding portion having a grounding portion at a potential point, and connected to the DC-AC converter or the midpoint grounding portion, and the grounding portion of the midpoint grounding portion is used as a reference potential in the DC power supply path. A second leakage detection unit that detects a DC leakage current

  Further, the present invention is the above-described power distribution system, wherein the midpoint grounding unit includes a DC-DC conversion unit connected to the DC power source or a terminal unit of the DC power supply path, and the second power source. It is provided between the leakage detecting unit.

  The present invention is the power distribution system described above, wherein the second leakage detection unit is provided between the DC-DC conversion unit connected to the DC power source and the midpoint grounding unit. Is.

  Further, the present invention is the above-described power distribution system, wherein the midpoint grounding portion is provided between both ends of the DC power feeding path in the DC power distribution portion, and is connected in series provided between the both ends. The connection point of the two resistors is grounded.

  Further, the present invention is the power distribution system described above, wherein the midpoint grounding unit is provided between both ends of the DC power supply path in the DC power distribution unit, and converts the supplied DC power into DC power. The connection point of the output lines of the two insulated DC-DC converters is grounded.

  Further, the present invention is the power distribution system described above, wherein the midpoint grounding unit is provided between both ends of the DC power supply path in the DC power distribution unit, and converts the supplied DC power into DC power. The connection point of the output lines of the two insulation type DC-DC converters is grounded, and further, a neutral line is connected from the DC power source to the connection point.

  Further, the present invention is the above-described power distribution system, wherein the passing current of the midpoint grounding portion is equal to or less than a ventricular fibrillation current or a separation limit current.

  Moreover, this invention is the power distribution system mentioned above, Comprising: The said DC power supplied to the said insulation type DC-DC conversion part is supplied from the said DC power source.

  Further, the present invention is the above-described power distribution system, wherein the second leakage detection unit is further provided in the DC power supply path wired on the DC power source side of the second leakage detection unit. Is.

  Further, the present invention is the above-described power distribution system, wherein the second leakage detection unit is further provided in a DC distribution board having the DC power feeding path wired to the DC distribution unit. .

  Moreover, this invention is a power distribution system mentioned above, Comprising: The said 2nd earth-leakage detection part is further provided in the direct current power supply path connected to the storage battery unit as said direct-current power source.

  Further, the present invention is the above-described power distribution system, wherein the second leakage detection unit is further provided in a main breaker of the DC distribution board having the DC power feeding path wired to the DC distribution unit. It is what

  Moreover, this invention is a power distribution system mentioned above, Comprising: Each said 2nd leakage detection part provided in the said DC distribution part is more than the said 1st leakage detection part provided in the said AC distribution part. Quickly detect leakage current.

  Moreover, this invention is the power distribution system mentioned above, Comprising: Each said 2nd leakage detection part provided in the said DC distribution part was provided toward the DC load side connected to the said DC distribution part. The second leakage detection unit detects the DC leakage current in the DC power supply path earlier as the second leakage detection unit.

  According to the present invention, it is possible to safely supply power using direct current power from a direct current power source such as a solar power generation device and alternating current power from an alternating current power source, and to detect leakage current without increasing the size of the system. It can be done reliably.

The block diagram which shows the structure of the power distribution system of 1st Embodiment. Explanatory drawing of the principal part of the midpoint grounding part provided in the direct current distribution part of the power distribution system of 1st Embodiment The block diagram which shows the structure of the power distribution system of 2nd Embodiment. Other main part enlarged explanatory drawing of the midpoint grounding part provided in the DC power distribution part Other main part enlarged explanatory drawing of the midpoint grounding part provided in the DC power distribution part The block diagram which shows the structure of the power distribution system of 3rd Embodiment. The block diagram which shows the structure of the power distribution system of 4th Embodiment. The block diagram which shows the structure of the power distribution system of 5th Embodiment The block diagram which shows the structure of the power distribution system of 5th Embodiment The block diagram which shows the structure of the power distribution system of 6th Embodiment The block diagram which shows the structure of the power distribution system of 6th Embodiment The block diagram which shows the structure of the power distribution system of 7th Embodiment The block diagram which shows the structure of the power distribution system of 7th Embodiment Other main part enlarged explanatory drawing of the midpoint grounding part provided in the DC power distribution part Other main part enlarged explanatory drawing of the midpoint grounding part provided in the DC power distribution part Other main part enlarged explanatory drawing of the midpoint grounding part provided in the DC power distribution part

  Hereinafter, an embodiment in which a power distribution system according to the present invention is applied to a detached house will be described in detail with reference to the drawings. However, the building to which the power distribution system according to the present invention can be applied is not limited to a detached house, and can also be applied to various buildings such as each dwelling unit or office of an apartment house.

  In each of the following embodiments, between the AC input to the DC-AC converter provided in the DC power distribution unit and the AC input to the AC-DC converter provided in the load circuit unit of the DC power distribution unit. The connection point to be connected is described as “AC connection part”.

  In each of the following embodiments, a DC input provided from a DC power source to a DC distribution board and a DC-AC conversion provided in the DC distribution unit are provided along a DC power supply path wired to the DC distribution unit. A DC power feeding path (distribution line) connecting the DC input to the section is referred to as a “DC connecting section”.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration of a power distribution system according to the first embodiment. The power distribution system according to the present embodiment uses AC power from an AC power source 11 of a commercial power source or DC power from a DC power source 300 such as a solar cell, a fuel cell, and a storage battery, for example, as an AC load or DC. It is a hybrid power distribution system that distributes power to each load.

  As shown in FIG. 1, the power distribution system according to the present embodiment includes an AC power source 11 that is a commercial power source (AC power system), an AC power distribution unit 100, a DC power distribution unit 200, and a DC power source 300. It is.

(AC Distribution Department)
The AC power source 11 is electrically connected to the AC power distribution unit 100 via the pole transformer 12. In FIG. 1, the pole transformer 12 is configured using an insulating transformer in which a primary side and a secondary side are insulated. On the secondary side of the pole transformer 12, a single-phase three-wire AC power supply path (AC circuit) in which the neutral wire is grounded to class B is formed, and the secondary side of the pole transformer 12 is the AC power distribution unit 100. It is connected to the.

  The AC power distribution unit 100 is connected to each AC load (AC load) from the AC distribution panel 101 via each AC branch circuit unit (branch Br) 133 and connecting the AC power distribution path 101 to the AC distribution board 101. The load wiring 135 is included.

  The AC distribution board 101 is configured to include a first leakage detection unit 131, a connection breaker 132, and a plurality of AC branch circuit units (branch Br) 133 provided in advance. In the AC power distribution unit 100 of FIG. 1, for example, five AC branch circuit units 133 are provided.

  The first earth leakage detector 131 is an earth leakage breaker that detects a leakage current flowing in the AC power supply path on the upstream side shown in FIG. 1, that is, on the AC power source 11 side instead of the DC power source 300 side in the power distribution system of FIG. (3P3E ELB (AC)). The first leakage detection unit 131 outputs a leakage detection signal to the interconnection breaker 132 when it is detected that a leakage current equal to or greater than a predetermined detection threshold flows in the AC power supply path in the AC distribution unit 100. In addition, the first leakage detection unit 131 has a timer inside, and when it is detected that a leakage current greater than or equal to a predetermined detection threshold flows in the AC power supply path in the AC distribution unit 100 for a predetermined time or more, A leakage detection signal may be output to the interconnection breaker 132.

  The first leakage detection unit 131 includes a zero-phase current transformer (ZCT). The first leakage detection unit 131 exceeds the predetermined detection threshold of the first leakage detection unit 131 based on, for example, the waveform of the AC leakage current of one cycle or 1.5 cycles output from the zero-phase current transformer. When the leak current section exceeds a predetermined time threshold, a leak in the AC power supply path is detected. In the power distribution system of each embodiment, the AC power distribution unit 100 and the DC power distribution unit 200 are insulated by a DC-AC conversion unit 240. For this reason, the first leakage detection unit 131 cannot detect a leakage in the DC power supply path wired to the DC distribution unit 200.

  The interconnection breaker 132 is connected in series to the first leakage detection unit 131 and blocks the AC power supply path (AC circuit) based on the leakage detection signal output from the first leakage detection unit 131.

  For example, in the AC distribution board 101 of FIG. 1, the AC branch circuit unit 133 supplies AC power based on an AC voltage of 200 V to an AC load (AC load) connected to the AC branch circuit unit 133.

  Inside the AC distribution board 101, a main breaker (not shown), a plurality of branch breakers 133, and the like are housed in a box with a door, for example, similarly to a residential distribution board. A commercial power supply as an AC power source 11 is connected to the primary side of the main breaker, and a plurality of conductive bars (not shown) of an AC power supply path are connected to the secondary side of the main breaker. A branch breaker 133 is electrically connected. Further, the output line of the DC-AC conversion unit 240 is drawn into and electrically connected to the box of the AC distribution board 101, and the output line of the DC-AC conversion unit 240 is connected to the box of the AC distribution board 101. Is electrically connected to an AC power supply path from the AC power source 11. Further, on the secondary side of the branch breaker 133, AC power is supplied to each AC load (AC load) in the house.

  In the power distribution system of FIG. 1, the AC power supply path of the AC power distribution unit 100 is drawn from the AC power distribution panel 101 to the DC power distribution unit 200 and is electrically connected thereto. A DC power supply path (DC power supply wiring) from the solar cell unit 330, the fuel cell unit 340, and the storage battery unit 350 is drawn into and electrically connected to the DC power distribution unit 200. DC power is supplied to a load (not shown).

(DC distribution section)
The DC power distribution unit 200 includes a DC distribution board 201 having a plurality of DC power supply paths connected therein. The DC power distribution unit 200 is connected to the AC power distribution unit 100 and the DC power source 300, respectively. The DC power distribution unit 200 includes an insulation type DC-AC converter 240 in which an AC power feeding path drawn into the DC power distribution unit 200 and a DC power feeding path wired in the DC power distribution unit 200 are insulated, and a second leakage detection. Part 250 and midpoint grounding part 260.

One of the DC-AC converters 240 (DC power source 300 side, downstream side) is connected to the midpoint grounding part 260, and the other (AC distribution unit 100 side, upstream side) is connected to the AC connection part 290 (terminals P ₀ and It is connected to the AC power feeding path of the AC power distribution unit 100 via the terminal P ₁ ). In the DC-AC converter 240, for example, two disconnectors 241 as a plurality of disconnectors, and an AC power supply path on the AC power distribution unit 100 side and a DC power supply path on the DC power distribution unit 200 side are electrically connected. Each has an isolated DC-AC inverter. The DC-AC converter 240 performs conversion from DC power to AC power.

  The DC-AC converter 240 includes a boost chopper circuit (not shown) that boosts the DC output from the solar cell unit 330 or the fuel cell unit 340. The DC-AC converter 240 includes a DC / AC converter (not shown) that converts the DC output boosted by the boost chopper circuit into sinusoidal AC power synchronized with the phase of the AC power source 11. The DC-AC converter 240 also controls a DC / AC converter (not shown) to adjust the output level of AC power, a grid connection protection device such as a disconnector 241, and the like. have.

  One of the second leakage detection units 250 (DC power source 300 side, downstream side) is connected to the DC power supply path 210 constituting the DC connection unit 280, and the other (AC distribution unit 100 side, upstream side) is the middle point. It is connected to the grounding part 260. The second leakage detection unit 250 detects a DC leakage current flowing in the DC power supply path using the ground of the midpoint grounding unit 260 (see FIG. 2) as a reference potential.

  The second leakage detection unit 250 includes a zero-phase current transformer, an integration circuit that integrates the output of the zero-phase current transformer, and the output of the integration circuit exceeds a predetermined detection threshold of the second leakage detection unit 250. And a determination circuit that determines that there is a leakage. The second leakage detection unit 250 integrates the output (effective value) of the zero-phase current transformer, and when this integration value exceeds the detection threshold for leakage detection in the second leakage detection unit 250, the second leakage detection unit 250 Detects electric leakage in the power supply path. In the power distribution system of each embodiment, the AC power distribution unit 100 and the DC power distribution unit 200 are insulated by a DC-AC conversion unit 240. For this reason, the second leakage detection unit 131 can detect a leakage in the DC power supply path wired to the DC distribution unit 200.

  The detection threshold value of leakage detection of the second leakage detection unit 250 is set to be the same as or lower than the detection threshold value of leakage detection of the first leakage detection unit 131. In the leakage detection of each leakage detection unit, in addition to the detection threshold value, when each leakage detection unit has a timer, a threshold value of a time exceeding the detection threshold value of the detected leakage current may be further included. Therefore, in this case, in each leakage detection of the first and second leakage detection units, the detection threshold value of the first leakage detection unit 131 is equal to or higher than the detection threshold value of the second leakage detection unit 250. It is assumed that the time threshold value of the current leakage detection unit 131 is longer than the time threshold value of the second leakage detection unit 250. The detection threshold value and the time threshold value of the leakage detection of each leakage detection unit are the same in the following embodiments.

  The second leakage detection unit 250 detects the leakage simultaneously with the leakage detection of the first leakage detection unit 131 or earlier than the first leakage detection unit 131. In other words, the second leakage detection unit 250 interrupts the DC power supply path simultaneously with the output of the leakage detection signal from the first leakage detection unit 131 to the interconnection breaker 132 or earlier than the output of the leakage detection signal. Is output to the DC-AC converter 240.

  The DC-AC converter 240 controls the circuit breaker 241 based on the leakage detection signal output from the second leakage detection unit 250 when the second leakage detection unit 250 detects leakage in the DC power supply path. And shut off the DC power supply path. Note that the second leakage detection unit 250 may incorporate a circuit breaker for the DC power supply path, and may directly block the DC power supply path when a leakage in the DC power supply path is detected. Although not shown in FIG. 1, the DC power distribution unit 200 is provided with a separate circuit breaker for the DC power supply path, and this circuit breaker is a DC power supply based on the leakage detection signal output from the second leakage detection unit 250. You may block the road. Further, the second leakage detection unit 250 outputs a leakage detection signal to the interconnection breaker 132 when detecting leakage in the DC power supply path on the DC power source 300 side (downstream side) from the second leakage detection unit 250. To do. Accordingly, the second leakage detection unit 250 causes the interconnection breaker 132 to cut off the DC power supply path to which the interconnection breaker 132 and the second leakage detection unit 250 are connected based on the leakage detection signal. Also good.

  One of the midpoint grounding units 260 (the DC power source 300 side and the downstream side) is connected to the DC connection unit 280 via the second leakage detection unit 250, and the other (the AC distribution unit 100 side and the upstream side) is DC. -It is connected to the AC converter 240. The midpoint grounding unit 260 is configured to have a grounding unit at a midpoint potential point between both ends of the DC power supply path wired to the DC power distribution unit 200.

FIG. 2 is an enlarged explanatory view of a main part of the midpoint grounding unit 260 provided in the DC power distribution unit 200 of the power distribution system according to the first embodiment. Midpoint grounded part 260, as shown in FIG. 2, is configured as two resistors R _1, R ₂ of the connecting portion equal series-connected resistance (midpoint connecting portion) M ₁ is grounded Yes. One end of the resistor R ₁ is connected to the connecting portion (midpoint connecting portion) M ₁ , and the other end is connected to a DC power supply path wired to the DC power distribution unit 200. Similarly, one end of the resistor R ₂ is connected to the connecting portion (middle point connecting portion) M ₁ , and the other end is connected to the DC power supply path having the opposite polarity wired to the DC power distribution unit 200. In FIG. 2, the second leakage detection unit 250 is connected to the DC connection unit 280. Therefore, in the power distribution system of the present embodiment, even when the AC power distribution unit 100 and the DC power distribution unit 200 are insulated in the DC-AC conversion unit 240 at the time of a power failure, the midpoint grounding between both ends of the DC power supply path is used as a reference potential. The presence / absence of electric leakage in the DC power distribution unit 200 can be detected.

The DC power distribution unit 200 further includes a load circuit unit 220 connected in parallel at the AC connection unit 290 (terminal P ₀ and terminal P ₁ ) on the AC power distribution unit 100 side (upstream side) from the second leakage detection unit 250. It is a configuration.

  The load circuit unit 220 is also connected in parallel with the AC distribution board 101 of the AC distribution unit 100. The load circuit unit 220 includes an insulated AC / DC converter 214 as an AC-DC converter, an insulated fourth DC / DC converter 224, and an insulated fifth DC / DC converter 234. It is a configuration.

The DC-AC converter 240 and the AC / DC converter 214 are electrically connected at an AC connection 290 (terminal P ₀ and terminal P ₁ ) on the AC power distribution unit 100 side. One of the DC side (downstream side) of the DC-AC converter 240, the DC side (downstream side) of the AC / DC converter 214, the fourth DC / DC converter 224, and the fifth DC / DC converter 234 is a DC distribution unit. 200 DC power supply paths 210 are electrically connected to each other. The DC power supply path 210 is configured using a connection bar or the like inside the DC distribution board 201.

  Further, the power distribution system of each embodiment may be configured not to include the AC / DC converter 214. In this case, the DC power connected to the storage battery unit 350 or the load circuit unit 220 is supplied with DC power obtained by converting the AC power supplied from the AC power distribution unit 100 in the DC-AC conversion unit 240. Alternatively, DC power from the solar cell unit 330 or the fuel cell unit 340 is supplied to the DC load connected to the storage battery unit 350 or the load circuit unit 220.

  The DC power output to the DC power supply path 210 is supplied to the storage battery unit 350 via the third branch circuit unit 245 and the third DC / DC converter 352. The DC power output to the DC power supply path 210 is further supplied to the second branch circuit unit 225 via the fourth DC / DC converter 224 and the second branch via the fifth DC / DC converter 234. To the branch circuit unit 235.

  The first branch circuit unit 225 supplies the DC power, which is stepped down to 48 V, for example, by the fourth DC / DC converter 224 to a DC load (not shown). The second branch circuit unit 235 supplies the direct-current power, which has been stepped down to 96 V by the fifth DC / DC converter 234, to a direct-current load (not shown). The third branch circuit unit 245 directly supplies DC power from the DC power supply path 210 to the DC load. The AC / DC converter 214 and the fourth and fifth DC / DC converters 224 and 234 have fuses 213, 223, and 233, respectively.

  The solar cell unit 330, the fuel cell unit 340, the storage battery unit 350, and the AC distribution board 101 are connected to the input ends of the DC distribution board 201. First to third branch circuit units 225, 235, and 245 for DC loads are connected to the output terminals of the DC distribution board 201.

  The DC distribution board 201 is a DC-AC converter 240, a first DC / DC converter 333, a second DC / DC converter 342, an AC / DC converter 214, and a fourth DC / DC as input / output converters. It has a converter 224 and a fifth DC / DC converter 234. The DC distribution board 201 may be connected to an information processing device including a control unit and a display unit (not shown).

  The information processing apparatus not shown in FIG. 1 has a control unit such as a microcomputer, and controls the operation of each unit of the DC distribution board 201 in the DC distribution unit 200. The control unit performs the ON / OFF control of the operation of each converter of the DC-AC converter 240, the DC / DC converters 333, 342, 352, 224, 234, and the AC / DC converter 214, and the output voltage control, and the display unit Display control (not shown) is performed.

  The display unit is composed of a liquid crystal display device such as an LCD (Liquid Crystal Display), and displays various information such as the operating state of the DC distribution board 201 by letters, numbers, images, etc. based on instructions from the control unit. Do. In addition, an operation unit (not shown) is connected to the power distribution system of FIG. 1, and through this operation unit, operation, an abnormal state, each measurement item, an abnormal history display, a clock setting, and the like can be performed. it can. Moreover, the solar cell voltage, storage battery voltage, AC voltage, output power, and abnormality occurrence time immediately before the occurrence of the abnormality can be simultaneously stored in the abnormality history. Further, as the operation unit, not only the operation unit attached to the DC distribution board 101 but also a remote operation unit (remote control or home personal computer) may be used to perform the above setting via a communication terminal.

  The output path of the solar cell unit 330 is connected to the DC-AC converter 240 via the DC power supply path 210, and passes through the first to third branch circuit sections 225, 235, 245 of the DC distribution board 201. Connected to a DC load (not shown).

  The DC-AC converter 240 converts the DC power output from the solar cell unit 330 into AC power synchronized with the phase of the AC power source 11 that is a commercial power supply, and outputs the converted AC power to the commercial power supply. Reverse current. The DC-AC converter 240 includes an AC / DC converter that converts AC power into DC power, and converts AC power output from the AC distribution path 100 to DC power via the AC power supply path. To the DC power supply path wired to the DC power distribution unit 200.

  The first DC / DC converter 333 serving as the DC-DC converter converts the DC power output from the solar cell panel 331 into a desired voltage level set in the first DC / DC converter 333 in advance. Output.

  The second DC / DC converter 342 converts the DC power output from the fuel battery cell 341 into a desired voltage level set in the second DC / DC converter 342 in advance and outputs the voltage.

  The third DC / DC converter 352 converts the DC power output from the storage battery main body 351 into a desired voltage level set in the third DC / DC converter 352 in advance and outputs the voltage. The third DC / DC converter 352 supplies the DC power from the DC power distribution unit 200 to the storage battery body 351 for charging.

  The AC / DC converter 214 converts the AC power supplied from the AC distribution board 101 into DC power having a desired voltage level set in advance in the AD / DC converter 214 and outputs the DC power.

  The first DC / DC converter 333 for the solar battery, the second DC / DC converter 342 for the fuel battery, and the third DC / DC converter 352 for the storage battery are each configured by a switching regulator, for example. . Each of these converters detects each output voltage from the solar battery panel 331, the fuel cell 341, and the storage battery 351, and controls the output voltage so that the detected output voltage matches the preset target voltage ( A constant voltage control method (feedback control) is used.

  The AC / DC converter 214 is configured by, for example, a switching regulator and an inverter. The AC / DC converter 214 rectifies the AC voltage into a DC voltage, performs constant voltage control of the output voltage by feedback control, and sets the desired AC / DC converter 214 in advance from the AC power output from the AC power distribution unit 100. It converts to DC power of the voltage level.

  The output terminals of the first DC / DC converter 333 for the solar cell, the second DC / DC converter 342 for the fuel cell, the third converter 352 for the storage battery, and the AC / DC converter 214 are connected to the DC power supply path 210. Are connected in parallel. The output terminals of these converters are connected to the DC power supply path 210 via current fuses, and the DC power supply path 210 is further provided with an external protection circuit (not shown) as required. One or a plurality of DC powers of the DC power converted to a desired voltage level are supplied to the DC load via the branch circuits 225, 235, and 245 for DC load.

  Further, the DC-AC converter 240 has a function of charging a storage battery at night and a function of discharging a storage battery during the day (preventing reverse power flow) in addition to a general function of reverse power flow of photovoltaic power generation. Both can be used effectively.

  At this time, since the reverse power flow to the commercial power source (AC power) is not recognized for the DC power discharged from the storage battery, it is necessary to change the discharge power according to the usage condition of the AC load. For example, the received power detection unit attached to the receiving point of the commercial power supply detects the power flowing from the commercial power supply, and performs reverse power flow prevention control so that the reverse power flow from the storage battery does not occur.

(DC power source)
The DC power distribution unit 200 is electrically connected to the solar cell unit 330, the fuel cell unit 340, and the storage battery unit 350 that constitute the DC power source 300.

  The solar cell unit 330 receives sunlight to generate electric power by photoelectric conversion, outputs direct current power based on this power generation, and constitutes a solar power generation device as an example of direct current power generation equipment. The solar cell unit 330 includes, for example, a solar cell panel 331 that can output a DC voltage of 350 V and a DC power of 5.5 kW, and a connection box 332. The solar cell panel 331 of the solar cell unit 330 is connected to a first DC / DC converter 333 that is a non-insulating solar cell converter via a connection box 332. When the output from the solar cell panel 331 is lower than a preset output value, a boost converter (not shown) may be provided between the solar cell panel 331 and the connection box 332.

  The fuel cell unit 340 includes a fuel cell 341 that can output a DC voltage of 130 V and a DC power of 1 kW, for example. The fuel cell 341 of the fuel cell unit 340 is connected to a second DC / DC converter 342 that is an insulating fuel cell converter.

  The storage battery unit 350 is configured by a secondary battery capable of charging DC power and discharging (output) the charged DC power. The storage battery unit 350 includes a storage battery main body 351 capable of outputting, for example, a 120 V DC voltage and 6 kW DC power. The storage battery main body 351 of the storage battery unit 350 is connected to a third DC / DC converter 352 that is a non-insulated storage battery converter. The third DC / DC converter 352 is used for charging and discharging the storage battery main body 351. Further, although the storage battery unit 350 is mounted on the DC distribution board 201, it can be added outside the DC distribution board 201 and used as an additional power source.

  The output from the DC power source 300 is input to the DC-AC converter 240 via the DC power supply path 210. The DC-AC converter 240 may convert DC power from the DC power source 300 into AC power and distribute the AC power to the AC power distribution unit 100 (reverse power flow).

  As described above, in the power distribution system according to the present embodiment, the second leakage detection unit 250 that detects the DC leakage current in the DC power supply path is provided on the DC power source 300 side (downstream side) of the insulation type DC-AC conversion unit 240. Have. In addition, the power distribution system of the present embodiment further includes a midpoint grounding unit 260 that is connected to the DC-AC conversion unit 240 and that has a midpoint potential point between both ends of the DC power supply path grounded. The second leakage detection unit 250 is connected to the midpoint grounding unit 260 and detects a DC leakage current flowing in the DC power supply path using the grounding unit of the midpoint grounding unit 260 as a reference potential.

  Therefore, in the power distribution system of the present embodiment, even if both ends of the DC power supply path wired to the DC power distribution unit 200 are grounded at the midpoint, and the AC power distribution unit 100 and the DC power distribution unit 200 are insulated during a power failure, It is possible to detect a leakage of the DC power distribution unit 200 using the ground unit 260 as a reference potential.

  As described above, the first earth leakage provided in the AC distribution board 101 of the AC distribution unit 100 using the insulation type DC-AC converter 240, the second earth leakage detection unit 250, and the midpoint grounding unit 260. It is possible to detect electric leakage easily and at the same time or earlier than the detection unit 131. The power distribution system according to the present embodiment uses the direct current power from the direct current power source and the alternating current power from the alternating current power source to use the alternating current load connected to the alternating current distribution unit 100 and the direct current load connected to the direct current distribution unit 200. Can be supplied safely. Furthermore, the power distribution system according to the present embodiment can realize a power distribution safety management function without greatly changing the conventional power distribution system.

  In addition, the detection threshold value of leakage detection in the second leakage detection unit 250 is set to be lower than the detection threshold value of leakage detection in the first leakage detection unit 131 provided in the AC distribution unit 100. Further, the second leakage detection unit 250 has a smaller leakage condition, that is, the leakage current detection threshold in the second leakage detection unit 250 is equal to or smaller than the leakage current detection threshold in the first leakage detection unit 131. Set. Thereby, the second leakage detection unit 250 can determine the leakage detection earlier than the first leakage detection unit 131.

  That is, when a leakage current exceeding a predetermined threshold value is generated in the DC power supply path, the leakage detection is performed in the second leakage detection unit 250 of the DC distribution unit 200 at the same time or earlier than the interconnection breaker 132 of the AC distribution unit 100. The

  Therefore, the power distribution system according to the present embodiment can detect a leakage with the ground included in the midpoint grounding unit 260 of the DC power distribution unit 200 as a reference potential. Furthermore, the power distribution system according to the present embodiment can reliably stop the operation of the power distribution system when an abnormality such as a power failure or electric leakage occurs, and can provide a highly safe power distribution system.

  In the present embodiment, the leakage detection by the second leakage detection unit 250 is performed simultaneously with or earlier than the first leakage detection unit 131. However, the first leakage detection unit 131 and the second leakage detection unit 250 do not have a difference in detection threshold (and time threshold), and the gap between the pole transformer 12 and the first leakage detection unit 131 is not. The delay circuit may be connected in series. Thereby, before the middle point grounding (neutral wire grounding) of the AC power distribution unit 100 is disconnected from the ground, that is, before the neutral wire is phase-lost, the second leakage detection unit 250 of the DC power distribution unit 200 is connected to the DC power supply path. It is also possible to perform leakage detection at. In this way, the power distribution system can be reliably stopped when an abnormality occurs due to the presence of the delay circuit, regardless of the setting of the detection threshold (and time threshold).

  Moreover, according to the structure of the power distribution system of this embodiment mentioned above, the element required for direct-current power supply can be accommodated in the same container as a direct current distribution board, and the construction of the power distribution system with easy installation and maintenance is possible. It becomes possible. In the present embodiment, each element of the DC distribution unit 200 is housed in the same container as the DC distribution board 201, but it goes without saying that it may be separately arranged as necessary.

  In the power distribution system of this embodiment, the DC-AC converter 240 is an insulation type, and the AC-DC converter 214 is an insulation type. On the other hand, the first DC / DC converter 333, the second DC / DC converter 342, the third DC / DC converter 352, the fourth DC / DC converter 224, and the fifth DC / DC converter 234 are non- Any of the insulation type and the insulation type can be applied. The first, second, third, fourth, and fifth DC / DC converters 333, 342, 352, 224, and 234 can be applied to both non-insulating / insulating types. The same applies to each of the embodiments. In the case of the non-insulating type, the configuration of each converter can be reduced, and in the case of the insulating type, there is an effect that power conversion can be safely performed in each converter.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram illustrating a configuration of a power distribution system according to the second embodiment.

In the power distribution system of this embodiment, as shown in the block diagram of FIG. 3, the midpoint grounding portion 260 </ b> A is provided between both ends of the DC power supply path 210. One of the midpoint grounding portions 260 </ b> A is connected to the terminal portion of the DC power supply path 210, and the other (the load circuit portion 220 side, the lower side in the drawing) is connected to the second leakage detection unit 250. Midpoint grounded part 260A, as shown in FIG. 3 or FIG. 14, the connection point M ₁ of the series connection of resistors R ₁ and R ₂ is a configuration in which the grounded. Resistor R ₁ has one end connected to the terminal P ₃ of the DC feed line 210, the other end is connected to the connection portion M ₁ which is grounded. Resistor R ₂ has one end connected to the terminal P ₂ of the DC feed line 210, the other end is connected to the connection portion M ₁ which is grounded.

  The other parts in the power distribution system of the present embodiment are the same as those of the power distribution system of the first embodiment shown in FIG.

  According to the power distribution system of the second embodiment, the second leakage detection unit 250 uses the ground included in the midpoint grounding portion 260A provided between both ends of the DC power supply path 210 as a reference potential, and the DC power supply path 210. The direct current leakage current in can be detected. Therefore, the second leakage detection unit 250 of the power distribution system of the second embodiment can detect the insulation deterioration of each converter in a wide range connected to the DC power supply path 210 with high accuracy. Also in this embodiment, each element of the DC distribution unit 200 is housed in the same container as the DC distribution board 201, but it goes without saying that it may be separately arranged as necessary.

  Further, in each of the embodiments described above, the midpoint grounding portions 260 and 260A can be configured as the midpoint grounding portions 260B and 260C in FIG. 4 or FIG. FIGS. 4 and 5 are other main parts enlarged explanatory views of the midpoint grounding parts 260 </ b> B and 260 </ b> C provided in the DC power distribution part 200.

  In FIG. 4, one of the midpoint grounding portions 260B (the DC power source 300 side and the downstream side) is connected to the DC connection portion 280 via the second leakage detection unit 250, and the other (the AC power distribution 100 side and the upstream side). ) Is connected to the DC-AC converter 240. The midpoint grounding portion 260B has a grounding portion at a midpoint potential point between both ends of the DC power supply path in the DC power distribution unit 200.

Specifically, the midpoint grounded part 260B has two input terminals _{W 1} and Isolated converters 270a and output lines of the insulated converter 270b having two input terminals _{W 3} and _{W 4} with _{W 2} one connection point (midpoint connecting portion) M ₂ is configured to be grounded. Here, DC power from the DC power source 300 is supplied to the input terminals W ₁ and W ₂ , W ₃ and W ₄ of the converters 270a and 270b. Since the DC power from the DC power source 300 is supplied to the input terminals W ₁ and W ₂ , W ₃ and W ₄ of the converters 270a and 270b, the DC power distribution unit 200 can stably supply the DC power even during a power failure. Supply to DC load becomes possible.

The other output line of the converter 270a is connected to the plus (+) output terminal W ₅ of the DC power feed path having a polarity, negative and the other output line of the converter 270b (-) output terminal of a DC power feed path having a polarity W ₆ It is connected to the.

  In the midpoint grounding portion 260B of FIG. 4, since no resistor is used unlike the midpoint connection portion 260 of FIG. 2, no heat loss occurs in the midpoint grounding portion 260B, and the isolated converters 270a and 270b Since it is used, the reference potential can be reliably obtained. Therefore, the power distribution system of each embodiment can safely detect the leakage based on the DC leakage current in the DC distribution unit 200 by using the midpoint grounding portion 260B of FIG.

Incidentally, the midpoint grounded part 260A of the second embodiment described above, when using the resistor R ₁ and R ₂ are configured are not arranged as shown in FIG. 2, as shown in FIG. 14 Be placed. FIG. 14 is an enlarged explanatory view of another main part of the midpoint grounding part 260A provided in the DC power distribution part 200 in the power distribution system of the second embodiment.

  As shown in FIG. 14, one of the midpoint grounding portions 260 </ b> A is connected to the terminal portion of the DC power supply path 210, and the other (the load circuit portion 220 side, the lower side in the drawing) is connected to the second leakage detection unit 250. ing.

In the case where the midpoint grounded part 260A of the second embodiment is constituted by the resistance R ₁ and R ₂ instead converters 270a and 270b are not arranged as shown in FIG. 4 or 5, It arrange | positions like the midpoint grounding part 260B and 260C of FIG. 15 or FIG. 15 and 16 are enlarged explanatory views of other main parts of the midpoint grounding portions 260B and 260C provided in the DC power distribution unit 200 in the power distribution system according to the second embodiment.

  As shown in FIG. 15 or FIG. 16, one of the midpoint grounding portions 260 </ b> B and 260 </ b> C is connected to the terminal end of the DC power supply path 210 and the other (opposite side of the terminal end of the DC power supply path 210) is the second leakage. It is connected to the detection unit 250.

In FIG. 5, the neutral grounding portion 260 </ b> C has a neutral line NL wired from the DC power source 300 side connected to a connection point (midpoint connection portion) M <b> 2 of each output line between the converter 270 a and the converter 270 _b. It has a configuration. Since the configuration of each other part of the midpoint grounding portion 260C is the same as that of the midpoint grounding portion 260B in FIG. 4, the description of the same contents is omitted.

In the middle point grounding portion 260C in FIG. 5, unlike the middle point grounding portion 260B in FIG. 4, unlike the middle point grounding portion 260 in FIG. 2, no resistance is used. do not do. Further, in the midpoint grounding portion 260C of FIG. 5, as in the case of the midpoint grounding portion 260B of FIG. 4, the insulating converters 270a and 270b are used, so that the reference potential can be reliably obtained. Therefore, the power distribution system of each embodiment can safely detect the leakage based on the DC leakage current in the DC distribution unit 200 by using the midpoint grounding portion 260B of FIG. Furthermore, since the midpoint grounded part neutral line in 260C of FIG. 5 is connected to the midpoint connecting portion M _2, the power distribution system of the embodiment, as compared with the case of using the midpoint grounded part 260B of FIG. 4 Two DC voltage outputs can be configured.

  In addition, it is preferable that the passing current (output current) of the above-described various midpoint grounding portions 260, 260A, 260B, and 260C is equal to or less than the ventricular fibrillation current or equal to or less than the separation limit current. Thereby, the influence with respect to the human body of a leakage current can be reduced.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a block diagram illustrating a configuration of a power distribution system according to the third embodiment.

  The power distribution system of the third embodiment is a modification of the power distribution system of the first embodiment described above. Further, as shown in the block diagram of FIG. Are connected in series. The other parts in the power distribution system of the present embodiment are the same as those of the power distribution system of the first embodiment shown in FIG.

  The power distribution system of the third embodiment can detect a leakage current flowing in the DC power supply path 210 in a wide range of the DC power supply path 210 by including the second leakage detection unit 250A. In this case, the second leakage detection unit 250A can cause the circuit breaker (not shown) connected in series to the DC power supply path 210 in FIG. 6 to interrupt the DC power supply path (DC circuit). . In this embodiment as well, each element of the DC distribution unit 200 is housed in the same container as the DC distribution board 201, but it goes without saying that it may be separately arranged as necessary. Moreover, about the 1st DC / DC converter 333 and the 3rd DC / DC converter 352, the direction using the non-insulation type | mold can perform the leakage protection of the wiring to the solar cell panel 331 and the storage battery 351.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a block diagram illustrating a configuration of a power distribution system according to the fourth embodiment.

  As shown in the block diagram of FIG. 7, the power distribution system of the fourth embodiment is a region corresponding to a distribution line to the load circuit unit 220 of the DC power supply path 210 as a modification of the power distribution system of the first embodiment. A second leakage detector 250B is further provided along the DC power supply path 210. The other parts in the power distribution system of the present embodiment are the same as those of the power distribution system of the first embodiment shown in FIG.

  According to the power distribution system of the fourth embodiment, in addition to the effects of the power distribution system of the first embodiment described above, leakage detection is performed on either the load circuit unit 220 side or the load circuit unit 220 side of the DC power distribution unit 200. Can be identified in detail. In this embodiment as well, each element of the DC distribution unit 200 is housed in the same container as the DC distribution board 201, but it goes without saying that it may be separately arranged as necessary. Moreover, about the 1st DC / DC converter 333 and the 3rd DC / DC converter 352, the direction using the non-insulation type | mold can perform the leakage protection of the wiring to the solar cell panel 331 and the storage battery 351.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIGS. 8 and 9 are block diagrams illustrating a configuration of a power distribution system according to the fifth embodiment.

  As shown in the block diagrams of FIGS. 8 and 9, the power distribution system of the fifth embodiment is a modification of the power distribution system of the third and fourth embodiments described above. Is provided along the DC power supply path 210 wired to the load circuit section 220. Since the other parts in the power distribution system of the present embodiment are the same as those of the power distribution system of the fourth embodiment shown in FIG. 4, the description thereof is omitted here, but the same parts are denoted by the same reference numerals.

  According to the power distribution system of the fifth embodiment, in addition to the effects of the power distribution systems of the third and fourth embodiments described above, leakage generated in the DC power supply path 210 of the load circuit unit 220 of the DC power distribution unit 200 is prevented. Can be detected. In this embodiment as well, each element of the DC distribution unit 200 is housed in the same container as the DC distribution board 201, but it goes without saying that it may be separately arranged as necessary.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIGS. 10 and 11 are block diagrams illustrating a configuration of a power distribution system according to the sixth embodiment.

  As shown in the block diagrams of FIGS. 10 and 11, the power distribution system of the sixth embodiment is a modification of the power distribution system of the fifth embodiment described above. 210 and the storage battery unit 350. The other parts in the power distribution system of the present embodiment are the same as those of the power distribution system of the fifth embodiment shown in FIGS. 8 and 9, so the description thereof is omitted here, but the same parts are denoted by the same reference numerals. .

  According to the power distribution system of the sixth embodiment, in addition to the effects of the power distribution system of the fifth embodiment described above, the third DC / DC for the storage battery if the third DC / DC converter 352 is non-insulated. Electric leakage from the converter 352 to the DC power supply path 210 can be detected. In this embodiment as well, each element of the DC distribution unit 200 is housed in the same container as the DC distribution board 201, but it goes without saying that it may be separately arranged as necessary. Moreover, about the 1st DC / DC converter 333 and the 3rd DC / DC converter 352, the direction using the non-insulation type | mold can perform the leakage protection of the wiring to the solar cell panel 331 and the storage battery 351.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described with reference to FIGS. 12 and 13 are block diagrams illustrating a configuration of a power distribution system according to the seventh embodiment.

  As shown in the block diagrams of FIGS. 12 and 13, the power distribution system according to the seventh embodiment is a modification of the power distribution system according to the sixth embodiment described above. This is further provided between 210 and the third branch circuit unit 245. Note that the second leakage detection unit 250E constitutes a main breaker provided in the DC distribution board 201. The other parts in the power distribution system of the present embodiment are the same as those of the power distribution system of the sixth embodiment shown in FIGS. 10 and 11, and thus the description thereof is omitted here, but the same parts are denoted by the same reference numerals. .

  According to the power distribution system of the present embodiment, in addition to the effects of the power distribution system of the sixth embodiment, when a leakage current is detected between the DC power supply path 210 and the second leakage detection unit 250E, it is not illustrated. The DC power supply path 210 (DC circuit) can be interrupted using a circuit breaker. Thereby, since the power distribution system of this embodiment can limit a leak location, the system down of the whole power distribution system can be prevented, and the safety of a power distribution system can be aimed at. In this embodiment as well, each element of the DC distribution unit 200 is housed in the same container as the DC distribution board 201, but it goes without saying that it may be separately arranged as necessary.

  While various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  In each of the above-described embodiments, each second leakage detection unit (250, 250A, 250B, 250C, 250D, 250E) provided in the DC distribution unit 200 is a first leakage provided in the AC distribution unit 100. The leakage detection can be performed earlier than the detection unit 131.

  Furthermore, each second leakage detection unit provided in the DC distribution unit 200 can detect the leakage earlier in the order of the second leakage detection units 250E, 250D, 250C, 250A, 250 in FIG. 12, for example. it can. That is, the second leakage detectors 250E, 250D, 250C, 250A, 250 can detect leakage in the order of the second leakage detectors 250E, 250D, 250C, 250A, 250 in advance. It is assumed that (time threshold) is set. Thereby, each 2nd earth-leakage detection part provided in direct current distribution part 200 can detect earth leakage earlier as the 2nd earth-leakage detection part provided toward the direct-current load side.

  Similarly, each second leakage detection unit provided in the DC distribution unit 200 detects the leakage earlier in the order of the second leakage detection units 250E, 250D, 250C, 250B, 250 in FIG. 13, for example. Can do. That is, the second leakage detection units 250E, 250D, 250C, 250B, 250 can detect leakage in the order of the second leakage detection units 250E, 250D, 250C, 250B, 250 in advance. It is assumed that (time threshold) is set.

  The second leakage detection unit 250B and the second leakage detection unit 250B are each configured such that the latter second leakage detection unit 250B can detect the leakage earlier than the former second leakage detection unit 250A. It is assumed that a detection threshold value (and time threshold value) for leakage detection is set.

DESCRIPTION OF SYMBOLS 11 AC power source 12 Pillar transformer 100 AC distribution part 101 AC distribution board 131 1st earth leakage detection part 132 Interconnection breaker 133 AC branch circuit part 200 DC distribution part 201 DC distribution board 210 DC power supply path 213, 223 233 Fuse 214 AC-DC converter 224 4th DC / DC converter 225 1st branch circuit part 234 5th DC / DC converter 235 2nd branch circuit part 240 DC-AC conversion part 241 Disconnector 245 1st 3 branch circuit units 250, 250A, 250B, 250C, 250D, 250E Second leakage detection units 260, 260A, 260B, 260C Midpoint grounding unit 270a, 270b Converter 280 DC connection unit 290 AC connection unit 300 DC power source 330 Solar cell unit 331 Solar cell panel 332 Connection box 333 1st DC / DC converter 340 fuel cell units 341 fuel cell 342 second DC / DC converter 350 battery unit 351 battery body 352 third DC / DC converter

Claims (14)

An AC power distribution unit having a single-phase three-wire power supply path grounded to a neutral wire, and distributing AC power from an AC power source to the power supply path; and a DC power distribution unit distributing DC power from the DC power source; A power distribution system comprising:
The AC power distribution unit
A first earth leakage detection unit that detects a leakage current in the feeding path of the AC power with the neutral wire ground as a reference potential;
The DC power distribution unit
An insulating DC-AC converter that converts DC to AC;
A midpoint grounding portion connected to the DC-AC conversion portion and having a grounding portion at a midpoint potential point of the DC power supply path;
A second leakage detection unit that is connected to the DC-AC converter or the midpoint grounding unit and detects a DC leakage current in the DC power supply path with the grounding unit of the midpoint grounding unit as a reference potential; Power distribution system. The power distribution system according to claim 1,
The midpoint grounding unit is a power distribution system provided between a DC-DC conversion unit connected to the DC power source or a terminal part of the DC power supply path and the second leakage detection unit. The power distribution system according to claim 1,
The second leakage detection unit is a power distribution system provided between a DC-DC conversion unit connected to the DC power source and the midpoint grounding unit. The power distribution system according to any one of claims 1 to 3,
The midpoint grounding section is provided between both ends of the DC power supply path in the DC distribution section, and is configured by grounding a connection point of two series-connected resistors provided between the both ends. system. The power distribution system according to any one of claims 1 to 3,
The midpoint grounding unit is provided between both ends of the DC power supply path in the DC power distribution unit, and is connected to the output lines of two insulating DC-DC conversion units that convert the supplied DC power into DC power. A power distribution system with grounded connection points. The power distribution system according to any one of claims 1 to 3,
The midpoint grounding unit is provided between both ends of the DC power supply path in the DC power distribution unit, and is connected to the output lines of two insulating DC-DC conversion units that convert the supplied DC power into DC power. A power distribution system configured by grounding a connection point, and further configured by connecting a neutral line from the DC power source to the connection point. The power distribution system according to claim 5 or 6,
A power distribution system in which a passing current of the midpoint grounding portion is equal to or less than a ventricular fibrillation current or a separation limit current. The power distribution system according to any one of claims 5 to 7,
The DC power supplied to the insulation type DC-DC converter is a power distribution system supplied from the DC power source. The power distribution system according to claim 8,
The power distribution system in which the second leakage detection unit is further provided in the DC power supply path wired on the DC power source side of the second leakage detection unit. The power distribution system according to claim 9,
A distribution system in which the second leakage detection unit is further provided in a DC distribution board having a feeding path for the DC power wired to the DC distribution unit. The power distribution system according to claim 10,
A power distribution system in which the second leakage detector is further provided in a DC power supply path connected to a storage battery unit as the DC power source. The power distribution system according to claim 11,
A distribution system in which the second leakage detection unit is further provided in a main breaker of the DC distribution board having the DC power supply path wired to the DC distribution unit. The power distribution system according to any one of claims 1 to 12,
Each of the second leakage detection units provided in the DC distribution unit detects a leakage current earlier than the first leakage detection unit provided in the AC distribution unit. It is a power distribution system as described in any one of Claims 1-13,
Each of the second leakage detection units provided in the DC power distribution unit is configured such that the second power leakage detection unit provided toward the DC load connected to the DC distribution unit is closer to the DC power supply path. Power distribution system that detects DC leakage currents faster.

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