CN110504670B - Power supply system and power supply method of direct-current power distribution network - Google Patents
Power supply system and power supply method of direct-current power distribution network Download PDFInfo
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- CN110504670B CN110504670B CN201910804328.1A CN201910804328A CN110504670B CN 110504670 B CN110504670 B CN 110504670B CN 201910804328 A CN201910804328 A CN 201910804328A CN 110504670 B CN110504670 B CN 110504670B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The embodiment of the invention discloses a power supply system and a power supply method of a direct current power distribution network, wherein the power supply system comprises: a transformer substation; the transformer substation comprises an alternating current first-stage bus, an alternating current second-stage bus, a first AC/DC device and a second AC/DC device; a first ring main unit line; the first ring main unit line comprises a ring main unit alternating current bus and a third AC/DC device; the wire inlet end of the third AC/DC device is electrically connected with the ring main unit alternating current bus, and the wire outlet end of the third AC/DC device is electrically connected with the direct current distribution network; a second ring main unit line; the second looped network cabinet line comprises a looped network cabinet alternating current bus and a fourth AC/DC device; and the wire inlet end of the fourth AC/DC device is electrically connected with the ring main unit alternating current bus, and the wire outlet end of the fourth AC/DC device is electrically connected with the direct current distribution network. The power supply system and the power supply method of the direct-current power distribution network provided by the embodiment of the invention can effectively improve the overload capacity and the power supply reliability of a power distribution network line.
Description
Technical Field
The embodiment of the invention relates to power supply and distribution technologies, in particular to a power supply system and a power supply method of a direct current power distribution network.
Background
With the continuous appearance of a large number of distributed concentrated photovoltaic and direct-current power loads, the establishment of an efficient direct-current power distribution network power supply scheme becomes important research content, and the power supply to the direct-current power distribution network is beneficial to the efficient incorporation of a direct-current power supply and a direct-current load into a direct-current power distribution network.
At present, in the existing power supply system of the medium-voltage direct-current power distribution network, alternating current interconnection is realized through flexible direct current, or a local medium-low-voltage direct-current power utilization scene is formed, some power supply systems and schemes of the medium-voltage direct-current power distribution network are lacked, and the power supply reliability of a direct-current power distribution part is not high. This way, overload capacity and power supply reliability of the distribution network line are affected.
Disclosure of Invention
The embodiment of the invention provides a power supply system and a power supply method of a direct-current power distribution network, which can effectively improve the overload capacity and the power supply reliability of a power distribution network line.
In a first aspect, an embodiment of the present invention provides a power supply system for a dc power distribution network, where the power supply system includes: a transformer substation; the transformer substation comprises an alternating current first-stage bus, an alternating current second-stage bus, a first AC/DC device and a second AC/DC device; the inlet end of the first AC/DC device is electrically connected with the alternating current first-stage bus, and the outlet end of the first AC/DC device is electrically connected with the direct current distribution network; the wire inlet end of the second AC/DC device is electrically connected with the alternating current two-section bus, the wire outlet end of the second AC/DC device is electrically connected with the direct current distribution network, and the wire outlet end of the second AC/DC device is also electrically connected with the wire outlet end of the first AC/DC device to form true bipolar direct current power supply;
a first ring main unit line; the first ring main unit line comprises a ring main unit alternating current bus and a third AC/DC device; the incoming line end of the third AC/DC device is electrically connected with the ring main unit alternating current bus, and the outgoing line end of the third AC/DC device is electrically connected with the direct current distribution network;
a second ring main unit line; the second looped network cabinet line comprises the looped network cabinet alternating current bus and a fourth AC/DC device; and the wire inlet end of the fourth AC/DC device is electrically connected with the ring main unit alternating current bus, and the wire outlet end of the fourth AC/DC device is electrically connected with the direct current distribution network.
Optionally, a positive outgoing line and a negative outgoing line are led out from the outgoing line end of the first AC/DC device; the positive outlet wire of the first AC/DC device is electrically connected with the positive wire of the direct current power distribution network, and the negative outlet wire of the first AC/DC device is connected to the zero pole of the direct current power distribution network; a positive outlet wire and a negative outlet wire are led out from the outlet end of the second AC/DC device; and the positive outlet wire of the second AC/DC device is electrically connected with the negative outlet wire of the first AC/DC device, and the negative outlet wire of the second AC/DC device is connected to the negative electrode of the direct-current power distribution network.
Optionally, a positive outgoing line and a negative outgoing line are led out from the outgoing line end of the third AC/DC device; and the positive outlet wire of the third AC/DC device is electrically connected with the positive wire of the direct current distribution network, and the negative outlet wire of the third AC/DC device is connected to the zero pole of the direct current distribution network.
Optionally, a positive outgoing line and a negative outgoing line are led out from the outgoing line end of the fourth AC/DC device; and a positive outlet wire of the fourth AC/DC device is connected to a zero pole of the direct current distribution network, and a negative outlet wire of the fourth AC/DC device is connected to a negative pole of the direct current distribution network.
Optionally, a switch is disposed on the positive outgoing line and the negative outgoing line of each AC/DC device.
Optionally, the direct-current power distribution network includes a direct-current first-stage bus, a direct-current second-stage bus, a direct-current third-stage bus, and a direct-current fourth-stage bus; the positive pole wire of the direct current first-stage bus is electrically connected with the positive pole outgoing wire of the first AC/DC device, the negative pole outgoing wire of the first AC/DC device is connected with the zero pole of the direct current first-stage bus, the negative pole wire of the direct current second-stage bus is electrically connected with the negative pole outgoing wire of the second AC/DC device, the positive pole outgoing wire of the second AC/DC device is connected with the zero pole of the direct current second-stage bus, the positive pole wire of the direct current third-stage bus is electrically connected with the positive pole outgoing wire of the third AC/DC device, the negative pole outgoing wire of the third AC/DC device is connected with the zero pole of the direct current third-stage bus, the negative pole wire of the direct current fourth-stage bus is electrically connected with the negative pole outgoing wire of the fourth AC/DC device, the positive pole outgoing wire of the fourth AC/DC device is connected with the zero pole of the direct current fourth-stage bus, and the zero pole of the direct current second-stage bus is electrically connected, the direct-current first-section bus is electrically connected with the direct-current third-section bus through a switch station, and the direct-current second-section bus is electrically connected with the direct-current fourth-section bus through the switch station.
Optionally, the dc distribution network is a medium-voltage dc distribution network, and the dc distribution network is connected with a concentrated load and a concentrated photovoltaic.
In a second aspect, an embodiment of the present invention further provides a power supply method for a dc power distribution network, where the power supply method is applied to the power supply system according to any embodiment of the present invention, and the power supply method includes:
a first AC/DC device and a second AC/DC device of a transformer substation are connected in series to form a true bipolar power supply mode to supply power to the direct-current power distribution network;
and respectively supplying power to the direct current distribution network by using a single-pole power supply mode of a third AC/DC device and a single-pole power supply mode of a fourth AC/DC device.
In a third aspect, an embodiment of the present invention further provides a power supply method for a dc power distribution network, where the power supply method is applied to the power supply system according to any embodiment of the present invention, and the power supply method includes:
a first AC/DC device and a second AC/DC device of a transformer substation are connected in series to form a true bipolar power supply mode to supply power to the direct-current power distribution network;
and supplying power to the direct current distribution network by using a single-pole power supply mode of a third AC/DC device or a single-pole power supply mode of a fourth AC/DC device.
Optionally, the power supply method further includes:
supplying power to the direct current distribution network through a first AC/DC device, a second AC/DC device and a third AC/DC device of the transformer substation, and controlling the first AC/DC device of the transformer substation to output a constant voltage and simultaneously controlling the third AC/DC device to output a constant power when an alternating current line connected with the third AC/DC device is overloaded, and injecting power into the alternating current line connected with the third AC/DC device;
optionally, the first AC/DC device, the second AC/DC device, and the fourth AC/DC device of the substation supply power to the DC distribution network, and when an AC line connected to the fourth AC/DC device is overloaded, the second AC/DC device of the substation is controlled to output a constant voltage, and at the same time, the fourth AC/DC device is controlled to output a constant power, and power is injected into the AC line connected to the fourth AC/DC device.
The power supply system and the power supply method of the direct current power distribution network comprise a transformer substation, a first ring main unit line and a second ring main unit line, wherein the transformer substation comprises an alternating current first-stage bus, an alternating current second-stage bus, a first AC/DC device and a second AC/DC device, the first AC/DC device and the second AC/DC device form true bipolar direct current power supply, the first ring main unit line comprises a ring main unit alternating current bus and a third AC/DC device, a wire inlet end of the third AC/DC device is electrically connected with the ring main unit alternating current bus, a wire outlet end of the third AC/DC device is electrically connected with the direct current power distribution network, and the second ring main unit line comprises a ring main unit alternating current bus and a fourth AC/DC device; and the wire inlet end of the fourth AC/DC device is electrically connected with the ring main unit alternating current bus, and the wire outlet end of the fourth AC/DC device is electrically connected with the direct current distribution network. The transformer substation can be interconnected with the first ring main unit line and the second ring main unit line through the direct-current power distribution network, and overload capacity and power supply reliability of the power distribution network line are improved.
Drawings
Fig. 1 is a schematic structural diagram of a power supply system of a dc power distribution network according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a power supply system of a dc power distribution network in an operation mode according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a power supply system of a dc power distribution network in another operation mode according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a substation according to an embodiment of the present invention;
fig. 5 is a flowchart of a power supply method for a dc power distribution network according to a second embodiment of the present invention;
fig. 6 is a flowchart of a power supply method for a dc power distribution network according to a third embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Based on the power supply system of the existing medium-voltage direct-current power distribution network, alternating-current interconnection is realized through flexible direct current, or a local medium-voltage and low-voltage direct-current power utilization scene is formed, the mode influences the overload capacity and the power supply reliability of a power distribution network line, and the embodiment provides the power supply system of the direct-current power distribution network. Exemplarily, referring to fig. 1, fig. 1 is a schematic structural diagram of a power supply system of a dc power distribution network according to an embodiment of the present invention, where the embodiment is applicable to a dc power distribution network for supplying power to an electrical load and an electrical device, and the power supply system includes: the system comprises a transformer substation 10, a first ring main unit line 20 and a second ring main unit line 30; wherein the content of the first and second substances,
the substation 10 includes an alternating-current first-stage bus 11, an alternating-current second-stage bus 12, a first AC/DC device 13, and a second AC/DC device 14; the incoming line end of the first AC/DC device 13 is electrically connected with the AC first-stage bus 11, and the outgoing line end of the first AC/DC device 13 is electrically connected with the DC distribution network; the incoming line end of the second AC/DC device 14 is electrically connected with the alternating current two-stage bus 12, the outgoing line end of the second AC/DC device 14 is electrically connected with the direct current distribution network 40, and the outgoing line end of the second AC/DC device 14 is also electrically connected with the outgoing line end of the first AC/DC device 13 to form true bipolar direct current power supply;
the first ring main unit line 20 comprises a ring main unit alternating current bus 21 and a third AC/DC device 22; the incoming line end of the third AC/DC device 22 is electrically connected with the ring main unit alternating current bus 21, and the outgoing line end of the third AC/DC device 22 is electrically connected with the direct current distribution network;
the second looped network cabinet line 30 comprises a looped network cabinet alternating current bus 21 and a fourth AC/DC device 31; the incoming line end of the fourth AC/DC device 31 is electrically connected with the ring main unit AC bus 21, and the outgoing line end of the fourth AC/DC device 31 is electrically connected with the DC distribution network.
Specifically, after a first AC/DC device 13 in the substation 10 takes power from an AC primary bus 11, the AC power is changed into DC power, a positive outlet wire of the first AC/DC device 13 is connected to a positive wire of a DC distribution network after passing through a B1 switch, and a negative outlet wire of the first AC/DC device 13 is connected to a zero pole of the DC distribution network after passing through a B3 switch. Correspondingly, after the second AC/DC device 14 in the substation 10 takes power from the AC two-stage bus 12, the AC power is changed into DC power, the positive outlet of the second AC/DC device 14 is connected to the zero pole of the DC distribution network through the B4 switch, and the negative outlet of the second AC/DC device 14 is connected to the negative pole of the DC distribution network through the B2 switch. After the third AC/DC device 22 of the first ring main unit line 20 gets power from the ring main unit AC bus 21, the AC power is changed into DC power, the positive outlet of the third AC/DC device 22 is connected to the positive line of the DC distribution network after passing through the B5 switch, and the negative outlet of the third AC/DC device 22 is connected to the zero pole of the DC distribution network after passing through the B6 switch. After the fourth AC/DC device 31 of the second looped network cabinet line 30 gets power from the looped network cabinet AC bus 21, the AC power is changed into DC power, the positive outlet wire of the fourth AC/DC device 31 is connected to the zero pole wire of the DC distribution network after passing through the B7 switch, and the negative outlet wire of the fourth AC/DC device 31 is connected to the negative pole of the DC distribution network after passing through the B8 switch. The voltage of the alternating current bus of the transformer substation and the voltage of the alternating current bus of the ring main unit can be both 10kV, any two lines of the line with the B1, the line with the B2 and the line jointly connected with the B3 and the B4 can be used for supplying power to the direct current distribution network, so that a true bipolar direct current power supply mode is formed at the outgoing line of the transformer substation, a direct current monopole power supply mode is formed at the line of the ring main unit, and the medium voltage direct current distribution network is supplied with power.
The power supply system of the direct current distribution network provided by the embodiment comprises a transformer substation, a first ring main unit line and a second ring main unit line, wherein the transformer substation comprises an alternating current section bus, the first AC/DC device and the second AC/DC device form true bipolar direct current power supply, the first ring main unit line comprises a ring main unit alternating current bus and a third AC/DC device, the incoming line end of the third AC/DC device is electrically connected with the ring main unit alternating current bus, the outgoing line end of the third AC/DC device is electrically connected with a direct current power distribution network, the second ring main unit line comprises a ring main unit alternating current bus and a fourth AC/DC device, the incoming line end of the fourth AC/DC device is electrically connected with the ring main unit alternating current bus, and the outgoing line end of the fourth AC/DC device is electrically connected with the direct current power distribution network. The transformer substation can be interconnected with the first ring main unit line and the second ring main unit line through the direct current distribution network, different buses of the transformer substation are interconnected, when the transformer substation is in power shortage or the ring main unit lines are in overcurrent and overload, the power shortage of the transformer substation can be supplemented and the overcurrent and overload of the ring main unit lines can be reduced by adopting a constant voltage and constant power control mode for the transformer substation and the ring main unit lines, so that the mutual power compensation of the transformer substation and the first ring main unit line as well as the transformer substation and the second ring main unit line can be realized, the overload capacity of the distribution network line can be improved, compared with the condition that the transformer substation or the ring main unit lines are independently used for supplying power for the direct current distribution network, the transformer substation can be interconnected with the ring main unit line through the two power supply modes of true bipolar power supply and unipolar power supply, for example, when the transformer substation is in power shortage, and different control modes are adopted to supplement the power shortage of the transformer substation, so that the transformer substation and the ring main unit line are ensured to normally supply power to the direct-current power distribution network, and the power supply reliability of the power supply system is improved.
Fig. 2 is a schematic structural diagram of a power supply system of a DC power distribution network provided in an embodiment of the present invention in an operation mode, fig. 3 is a schematic structural diagram of a power supply system of a DC power distribution network provided in an embodiment of the present invention in another operation mode, on the basis of the above technical solutions, optionally, referring to fig. 2 and fig. 3, a positive outgoing line and a negative outgoing line are led out from an outgoing line end of a first AC/DC device; a positive outlet wire of the first AC/DC device 13 is electrically connected with a positive wire of the direct current distribution network, and a negative outlet wire of the first AC/DC device 13 is connected to a zero pole of the direct current distribution network; a positive outlet wire and a negative outlet wire are led out from the outlet end of the second AC/DC device 14; and a positive outlet wire of the second AC/DC device 14 is electrically connected with a negative outlet wire of the first AC/DC device 13, and a negative outlet wire of the second AC/DC device 14 is connected to the negative electrode of the direct current distribution network.
Wherein, the positive outlet wire of the second AC/DC device 14 is electrically connected with the negative outlet wire of the first AC/DC device 13 to form true bipolar power supply, and alternating current is converted into direct current to supply power to a direct current distribution network.
Optionally, a positive outgoing line and a negative outgoing line are led out from the outgoing line end of the third AC/DC device 22; the positive outlet of the third AC/DC device 22 is electrically connected to the positive line of the DC distribution network, and the negative outlet of the third AC/DC device 22 is connected to the zero pole of the DC distribution network.
Specifically, when the first ring main unit line 20 is overcurrent, the direct current side of the first AC/DC device 13 adopts a constant voltage control mode, and the alternating current side of the third AC/DC device 22 adopts a constant power control mode; when the power shortage occurs to the AC section bus 11 of the transformer substation 10, injecting power into the AC section bus 11 through the DC distribution network, and supplementing the power shortage of the AC section bus 11 to the maximum extent, wherein the DC side of the third AC/DC device 22 adopts a constant voltage control mode, and the AC side of the first AC/DC device 13 adopts a constant power control mode; when the first ring main unit line 20 and the transformer substation 10 are both in power shortage, the direct current side of the first AC/DC device 13 adopts a constant voltage control mode, the third AC/DC device 22 adopts a constant power control mode, and the photovoltaic and energy storage converters in the direct current power distribution network adopt the constant power control mode, so that power mutual aid between the first ring main unit line 20 and the transformer substation 10 is realized.
Optionally, a positive outgoing line and a negative outgoing line are led out from the outgoing line end of the fourth AC/DC device; and a positive outlet wire of the fourth AC/DC device is connected to a zero pole of the direct-current power distribution network, and a negative outlet wire of the fourth AC/DC device is connected to a negative pole of the direct-current power distribution network.
Specifically, when the second looped network cabinet line 300 is in an overcurrent state, the direct current side of the second AC/DC device 14 adopts a constant voltage control mode, and the alternating current side of the fourth AC/DC device 31 adopts a constant power control mode; when the alternating-current second-stage bus 12 of the transformer substation 10 has power shortage, injecting power into the alternating-current second-stage bus 12 through the direct-current power distribution network, and supplementing the power shortage of the alternating-current second-stage bus 12 to the maximum extent, wherein the direct-current side of the fourth AC/DC device 31 adopts a constant-voltage control mode, and the alternating-current side of the second AC/DC device 14 adopts a constant-power control mode; when the second looped network cabinet line 30 and the transformer substation 10 are both in power shortage, the direct current side of the second AC/DC device 14 adopts a constant voltage control mode, and the fourth AC/DC device 31 adopts a constant power control mode, so that power mutual aid between the second looped network cabinet line 30 and the transformer substation 10 is realized.
Optionally, a switch is disposed on the positive outgoing line and the negative outgoing line of each AC/DC device, and the power supply line can be switched on and off by switching on and off the switch.
Optionally, with continued reference to fig. 1, the dc distribution network includes a dc first-stage bus 40, a dc second-stage bus 50, a dc third-stage bus 60, and a dc fourth-stage bus 70; the positive pole line of the direct current first-stage bus 40 is electrically connected with the positive pole outgoing line of the first AC/DC device 13, the negative pole outgoing line of the first AC/DC device 13 is connected with the zero pole of the direct current first-stage bus, the negative pole line of the direct current second-stage bus 50 is electrically connected with the negative pole outgoing line of the second AC/DC device 14, the positive pole outgoing line of the second AC/DC device 14 is connected with the zero pole of the direct current second-stage bus, the positive pole line of the direct current third-stage bus 60 is electrically connected with the positive pole outgoing line of the third AC/DC device 22, the negative pole outgoing line of the third AC/DC device 22 is connected with the zero pole of the direct current third-stage bus, the negative pole line of the direct current fourth-stage bus 70 is electrically connected with the negative pole outgoing line of the fourth AC/DC device 31, the positive pole outgoing line of the fourth AC/DC device 31 is connected with the zero pole of the direct current fourth-stage bus, the zero pole of the direct current first-stage bus 40 is electrically connected with the zero pole of the direct current second-stage bus 50, the direct current first-stage bus 40 is electrically connected with the direct current third-stage bus 60 through a switch station, and the direct current second-stage bus 50 is electrically connected with the direct current fourth-stage bus 70 through the switch station.
The switch of the switch station connecting the first direct-current bus 40 and the third direct-current bus 60 is closed, so that the first direct-current bus 40 and the third direct-current bus 60 can be electrically connected, the switch of the switch station connecting the second direct-current bus 50 and the fourth direct-current bus 70 is closed, so that the second direct-current bus 50 and the fourth direct-current bus 70 can be electrically connected, and therefore the transformer substation 10 is interconnected with the first ring main unit line 20 and the second ring main unit line 30.
Optionally, the direct-current distribution network is a medium-voltage direct-current distribution network, the direct-current distribution network is connected with a concentrated load and a concentrated photovoltaic, the direct-current distribution network can supply power for the concentrated load, and the concentrated photovoltaic can supply power for loads connected with the direct-current distribution network.
Fig. 4 is a schematic structural diagram of a substation according to an embodiment of the present invention, in which mutual regulation of power between buses of the same substation can be achieved by appropriately modifying the wiring manner of two AC/DC devices of the substation, as shown in fig. 4, two isolating switches B + and B-are arranged at the outlets of the two AC/DC devices, when the switches B + and B-are closed, the ac primary bus 11 and the ac secondary bus 12 of the substation 10 are interconnected, the mutual regulation of the power between the AC first-stage bus 11 and the AC second-stage bus 12 is realized by adopting control modes with different constant voltage and constant power for the first AC/DC device 13 and the second AC/DC device, different buses of the same transformer substation are interconnected, so that mutual power assistance of different buses of the same transformer substation is realized, namely, voltage is unchanged, and power can be adjusted according to needs; when the switches B + and B-are opened, the substation 10 is in a true bipolar supply mode, which supplies the DC distribution network by means of the first AC/DC device 13 and the second AC/DC device 14.
The power supply system of direct current distribution network that this embodiment provided, including transformer substation, first looped netowrk cabinet circuit and second looped netowrk cabinet circuit, transformer substation can improve the overload capacity and the power supply reliability of distribution network circuit through direct current distribution network and first looped netowrk cabinet circuit and second looped netowrk cabinet circuit interconnection.
Example two
The present embodiment further provides a power supply method for a dc power distribution network, and fig. 5 is a flowchart of the power supply method for the dc power distribution network according to the second embodiment of the present invention, which specifically includes the following steps:
and 110, connecting the first AC/DC device and the second AC/DC device of the transformer substation in series to form a true bipolar power supply mode, and supplying power to a direct current distribution network.
The transformer substation supplies power to the direct-current power distribution network in a true bipolar power supply mode, the voltage of the alternating-current side of the transformer substation can be 10kV, alternating current is converted into direct current through the first AC/DC device and the second AC/DC device, and the direct current is output to the power distribution network.
And 120, respectively supplying power to the direct current distribution network through a single-pole power supply mode of the third AC/DC device and a single-pole power supply mode of the fourth AC/DC device.
Specifically, the transformer substation is interconnected with the third AC/DC device and the fourth AC/DC device through the direct current power distribution network, the power supply system supplies power to the direct current power distribution network in a true bipolar power supply mode and a unipolar power supply mode, each AC/DC device is electrically connected with the direct current power distribution network through a line with a switch, when a certain AC/DC device fails, the switch on the connecting line of the failed AC/DC device and the direct current power distribution network can be disconnected to break the fault, and other AC/DC devices supply power to the direct current power distribution network normally.
The power supply method for the direct-current power distribution network provided by the embodiment is applied to the power supply system provided by any embodiment of the invention, and the transformer substation is interconnected with the third AC/DC device and the transformer substation is interconnected with the fourth AC/DC device to supply power to the direct-current power distribution network, so that the overload capacity and the power supply reliability of a power distribution network line are improved.
EXAMPLE III
Fig. 6 is a flowchart of a power supply method for a dc power distribution network according to a third embodiment of the present invention, where the power supply method is applied to a power supply system according to any embodiment of the present invention, and specifically includes the following steps:
and step 210, connecting the first AC/DC device and the second AC/DC device of the transformer substation in series to form a true bipolar power supply mode, and supplying power to a direct current power distribution network.
And step 220, supplying power to the direct current distribution network by using a single-pole power supply mode of the third AC/DC device or a single-pole power supply mode of the fourth AC/DC device.
Specifically, when a first AC/DC device, a second AC/DC device and a third AC/DC device of the transformer substation supply power to a direct current distribution network, when an alternating current line connected with the third AC/DC device is overloaded, the first AC/DC device of the transformer substation is controlled to output at a constant voltage, meanwhile, the third AC/DC device is controlled to output at a constant power, and power is injected into the alternating current line connected with the third AC/DC device.
When the first AC/DC device, the second AC/DC device and the fourth AC/DC device of the transformer substation supply power for a direct current distribution network, when an alternating current line connected with the fourth AC/DC device is overloaded, the second AC/DC device of the transformer substation is controlled to output at a constant voltage, the constant power output of the fourth AC/DC device is controlled, and power is injected into the alternating current line connected with the fourth AC/DC device.
The power supply method for the direct-current power distribution network provided by the embodiment of the invention is applied to the power supply system provided by any embodiment of the invention, and the transformer substation and the third AC/DC device are interconnected to supply power to the direct-current power distribution network, or the transformer substation and the fourth AC/DC device are interconnected to supply power to the direct-current power distribution network, so that the overload capacity and the power supply reliability of a power distribution network line are improved.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (8)
1. A power supply system for a dc power distribution network, the power supply system comprising:
a transformer substation; the transformer substation comprises an alternating current first-stage bus, an alternating current second-stage bus, a first AC/DC device and a second AC/DC device; the inlet end of the first AC/DC device is electrically connected with the alternating current first-stage bus, and the outlet end of the first AC/DC device is electrically connected with the direct current distribution network; the wire inlet end of the second AC/DC device is electrically connected with the alternating current two-section bus, the wire outlet end of the second AC/DC device is electrically connected with the direct current distribution network, and the wire outlet end of the second AC/DC device is also electrically connected with the wire outlet end of the first AC/DC device to form true bipolar direct current power supply;
a first ring main unit line; the first ring main unit line comprises a ring main unit alternating current bus and a third AC/DC device; the incoming line end of the third AC/DC device is electrically connected with the ring main unit alternating current bus, and the outgoing line end of the third AC/DC device is electrically connected with the direct current distribution network;
a second ring main unit line; the second looped network cabinet line comprises the looped network cabinet alternating current bus and a fourth AC/DC device; the incoming line end of the fourth AC/DC device is electrically connected with the ring main unit alternating current bus, and the outgoing line end of the fourth AC/DC device is electrically connected with the direct current distribution network;
a positive outlet wire and a negative outlet wire are led out from the outlet wire end of the first AC/DC device; a positive outlet wire of the first AC/DC device is electrically connected with a positive wire of the direct current distribution network, and a negative outlet wire of the first AC/DC device is connected to a zero pole of the direct current distribution network; a positive outlet wire and a negative outlet wire are led out from the outlet end of the second AC/DC device; the positive outlet wire of the second AC/DC device is electrically connected with the negative outlet wire of the first AC/DC device, and the negative outlet wire of the second AC/DC device is connected to the negative electrode of the direct-current power distribution network;
a positive outlet wire and a negative outlet wire are led out from the outlet end of the third AC/DC device; the positive outlet wire of the third AC/DC device is electrically connected with the positive wire of the direct current power distribution network, and the negative outlet wire of the third AC/DC device is connected to the zero pole of the direct current power distribution network;
a positive outlet wire and a negative outlet wire are led out from the outlet end of the fourth AC/DC device; and a positive outlet wire of the fourth AC/DC device is connected to a zero pole of the direct current distribution network, and a negative outlet wire of the fourth AC/DC device is connected to a negative pole of the direct current distribution network.
2. The power supply system of claim 1, wherein each AC/DC device has a switch disposed on the positive and negative outlets.
3. The power supply system of claim 1, wherein the dc distribution network includes a dc first segment bus, a dc second segment bus, a dc third segment bus, and a dc fourth segment bus; the positive pole wire of the direct current first-stage bus is electrically connected with the positive pole outgoing wire of the first AC/DC device, the negative pole outgoing wire of the first AC/DC device is connected with the zero pole of the direct current first-stage bus, the negative pole wire of the direct current second-stage bus is electrically connected with the negative pole outgoing wire of the second AC/DC device, the positive pole outgoing wire of the second AC/DC device is connected with the zero pole of the direct current second-stage bus, the positive pole wire of the direct current third-stage bus is electrically connected with the positive pole outgoing wire of the third AC/DC device, the negative pole outgoing wire of the third AC/DC device is connected with the zero pole of the direct current third-stage bus, the negative pole wire of the direct current fourth-stage bus is electrically connected with the negative pole outgoing wire of the fourth AC/DC device, the positive pole outgoing wire of the fourth AC/DC device is connected with the zero pole of the direct current fourth-stage bus, and the zero pole of the direct current second-stage bus is electrically connected, the direct-current first-section bus is electrically connected with the direct-current third-section bus through a switch station, and the direct-current second-section bus is electrically connected with the direct-current fourth-section bus through the switch station.
4. The power supply system of claim 1, wherein the dc distribution grid is a medium voltage dc distribution grid to which a concentrated load and a concentrated photovoltaic are connected.
5. A power supply method for a dc power distribution network, wherein the power supply method is applied to the power supply system according to claims 1 to 4, and the power supply method comprises:
a first AC/DC device and a second AC/DC device of a transformer substation are connected in series to form a true bipolar power supply mode to supply power to the direct-current power distribution network;
and respectively supplying power to the direct current distribution network by using a single-pole power supply mode of a third AC/DC device and a single-pole power supply mode of a fourth AC/DC device.
6. A power supply method for a dc power distribution network, wherein the power supply method is applied to the power supply system according to claims 1 to 4, and the power supply method comprises:
a first AC/DC device and a second AC/DC device of a transformer substation are connected in series to form a true bipolar power supply mode to supply power to the direct-current power distribution network;
and supplying power to the direct current distribution network by a single-pole power supply mode of a third AC/DC device or a single-pole power supply mode of a fourth AC/DC device.
7. The power supply method according to claim 6, characterized by further comprising:
and when an alternating current line connected with the third AC/DC device is overloaded, the first AC/DC device of the transformer substation is controlled to output constant voltage, and meanwhile, the third AC/DC device is controlled to output constant power, and power is injected into the alternating current line connected with the third AC/DC device.
8. The power supply method according to claim 6, characterized by further comprising:
and when an alternating current line connected with the fourth AC/DC device is overloaded, the second AC/DC device of the transformer substation is controlled to output constant voltage, and meanwhile, the fourth AC/DC device is controlled to output constant power, and power is injected into the alternating current line connected with the fourth AC/DC device.
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