CN113285518A - DC power supply system - Google Patents
DC power supply system Download PDFInfo
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- CN113285518A CN113285518A CN202110389582.7A CN202110389582A CN113285518A CN 113285518 A CN113285518 A CN 113285518A CN 202110389582 A CN202110389582 A CN 202110389582A CN 113285518 A CN113285518 A CN 113285518A
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- 230000002457 bidirectional effect Effects 0.000 claims abstract description 98
- 238000006243 chemical reaction Methods 0.000 claims abstract description 35
- 238000001514 detection method Methods 0.000 claims description 38
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 15
- 230000002159 abnormal effect Effects 0.000 description 13
- 239000002253 acid Substances 0.000 description 9
- 238000010586 diagram Methods 0.000 description 9
- 238000007599 discharging Methods 0.000 description 9
- 239000013589 supplement Substances 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000007667 floating Methods 0.000 description 3
- 230000005611 electricity Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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Classifications
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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
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/061—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for DC powered loads
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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
- H02J11/00—Circuit arrangements for providing service supply to auxiliaries of stations in which electric power is generated, distributed or converted
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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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
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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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0063—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
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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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply
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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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
Abstract
The present invention relates to a direct current power supply system, including: the charging module is externally connected with an alternating current power distribution system and converts alternating current input by the alternating current power distribution system into direct current to be output; the direct current distribution bus is connected with the charging module and supplies power to a direct current load connected to the direct current distribution bus; the bidirectional current conversion module is connected with the direct current distribution bus; and the storage battery module is connected with the bidirectional current conversion module.
Description
Technical Field
The application relates to the technical field of power supplies of nuclear power stations, in particular to a direct-current power supply system.
Background
A direct current power supply system in a nuclear power station supplies power to control loads (such as control, signal, protection and automatic devices) and power loads (such as direct current motors, inverters, emergency lighting and the like), relates to power supply of important loads such as nuclear reactor measurement, nuclear reactor protection groups, nuclear instruments and meters, emergency diesel engine control panels and the like, and plays a vital role in safe and stable operation of a nuclear power plant.
The storage battery is an important device of a direct current system of a nuclear power plant. Under normal operation, the storage battery is in a float charging state, the charger supplies power to downstream loads, and float charging current is provided for the storage battery. If too much impact load demand occurs in the system and the charger cannot provide enough impact load energy, the energy required for impact load is provided by the battery. When the alternating current power supply is lost or the charger breaks down, the charger stops working, and the storage battery starts discharging so as to ensure that a reliable power supply is provided for downstream loads within required time, ensure continuous power supply of important loads and ensure nuclear safety.
In the safety-level direct-current power supply system of the nuclear power plant in the prior art, a compressed air and supplementary fuel power generation system or other battery modules occupying a large amount of ground and volume space are used as a backup power supply. Along with the digital and intelligent transformation and promotion of nuclear power plants, some important safety level control systems and protection systems are transformed and expanded. Due to the limited space of the site, the power generation system of the compressed air and the supplementary fuel or other battery modules have the problems of low energy density, large occupied area, large occupied volume and the like. And the backup power supply in the prior art also has the problem that the direct current power supply system can not charge the backup power supply or the backup power supply can not completely supply power to the direct current system.
Disclosure of Invention
In view of the above, there is a need for a novel high-safety and high-energy-density dc power supply system based on lithium iron phosphate batteries.
In order to achieve the above object, the present invention provides a direct current power supply system including:
the charging module is externally connected with an alternating current power distribution system and converts alternating current input by the alternating current power distribution system into direct current to be output;
the direct current distribution bus is connected with the charging module and supplies power to a direct current load connected to the direct current distribution bus;
the bidirectional current conversion module is connected with the direct current distribution bus;
and the storage battery module is connected with the bidirectional current conversion module.
In one embodiment, the battery module comprises more than two groups of battery packs, and the battery module supplies power to the direct current distribution bus when the alternating current distribution system is powered off.
In one embodiment, the bidirectional converter module includes a bidirectional converter device, the bidirectional converter device is connected to the battery module, and the bidirectional converter module charges the battery module when the ac power distribution system is normally powered.
In one embodiment, the bidirectional current conversion module further includes a voltage detection device, the voltage detection device is connected to the bidirectional current conversion device and the dc power distribution bus, the voltage detection device corresponds to the bidirectional current conversion device one to one, and the voltage detection device monitors the voltage of the dc power distribution bus in real time and controls on/off of the bidirectional current conversion device.
In one embodiment, if the voltage detection device detects that the voltage of the direct current distribution bus is lower than a first voltage value, the voltage detection device controls the bidirectional converter device to be opened, and the storage battery module supplies power to the direct current distribution bus through the bidirectional converter module; the first voltage value is less than the rated voltage of the direct current distribution bus.
In one embodiment, if the voltage detection device detects that the voltage of the dc distribution bus is greater than or equal to a second voltage value, the voltage detection device controls the bidirectional converter device to be turned off, the bidirectional converter module automatically stops supplying power to the dc distribution bus, and the storage battery module stops supplying power; the second voltage value is the same as the rated voltage of the direct current distribution bus.
In one embodiment, if the voltage detection device detects that the voltage of the dc distribution bus is greater than or equal to the second voltage value and lasts for a certain time, the voltage detection device controls the bidirectional converter device to be turned on, and the bidirectional converter module charges the storage battery module.
In one embodiment, the bidirectional converter module is a BUCK-BOOST circuit, and the bidirectional converter module is designed in a staggered parallel mode by using high-power tubes.
In one embodiment, the input end of the BUCK-BOOST circuit is connected with the direct current distribution bus, and the output end of the BUCK-BOOST circuit is connected with the storage battery module; and when the voltage of the direct current distribution bus is greater than the voltage of the storage battery module, the BUCK-BOOST circuit is in a BOOST circuit boosting mode.
In one embodiment, when the dc distribution bus voltage is less than the battery module voltage, the BUCK-BOOST circuit is in a BUCK mode.
The invention has the beneficial effects that: the direct-current power supply system is connected with the bidirectional current conversion module through the storage battery module, and the bidirectional current conversion module is connected with the direct-current distribution bus. When the power supply of the power grid is normal, the charging module charges and stores power for the storage battery module through the direct-current power distribution bus; when the power supply of the power grid is abnormal, the storage battery module reversely supplies power to the direct current distribution bus through the bidirectional current conversion module, so that the direct current load on the direct current distribution bus can work normally, and the safety discharge function of the direct current bus can be effectively realized. And under the condition of abnormal power supply of the power grid, the direct-current load is still ensured to be continuously supplied for a long time, the power utilization requirement of safety-level downstream loads is met, and the safety and the reliability of important loads of the nuclear power station are improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a dc power supply system in an embodiment.
FIG. 2 is a schematic diagram of the BUCK-BOOST circuit.
Fig. 3 is a schematic structural diagram of a dc power supply system in another embodiment.
Fig. 4 is a schematic structural diagram of a dc power supply system in another embodiment.
Fig. 5 is a control logic diagram of the dc power system according to an embodiment.
Fig. 6 is a logic diagram of battery pack charging and discharging control of the dc power system according to an embodiment.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
In a direct current power supply system of a current nuclear power station, a lead-acid storage battery is generally adopted as a backup power supply. Along with the digital and intelligent transformation and promotion of nuclear power plants, some important safety level control systems and protection systems are transformed and expanded. Due to the limitation of field space, the lead-acid storage battery has low energy density, large occupied area and large occupied volume, and the requirement of a back-up power supply of a direct-current power supply system of a nuclear power station cannot be met by adopting the lead-acid storage battery for capacity expansion. The lithium iron phosphate battery has the advantages of good safety, high energy density, long service life, low self-discharge rate and the like. Therefore, on the basis of the lithium iron phosphate battery, a novel safety-level nuclear power station direct-current power supply system with high safety and high energy density is designed and researched, and the problem can be effectively solved. Therefore, a direct-current power supply system using a lithium iron phosphate battery as a storage battery is needed to replace the original safety-level lead-acid storage battery.
Referring to fig. 1 to 6, a dc power supply system for a nuclear power plant to provide dc power for a dc load, as shown in fig. 1, includes: the charging system comprises a charging module 10, a direct current distribution bus 20, a bidirectional converter module 30 and a storage battery module 40. The direct current distribution bus 20 is connected with the charging module 10, the bidirectional converter module 30 is connected with the direct current distribution bus 20, and the storage battery module 40 is connected with the bidirectional converter module 30.
The charging module 10 is externally connected to an ac power distribution system, and the charging module 10 converts ac power input by the ac power distribution system into dc power for output. The ac power distribution system includes, but is not limited to, 220V power grid, 380V power grid, and other ac power grids. The dc distribution bus 20 receives the converted dc power from the charging module 10, and the dc distribution bus 20 supplies power to the dc loads connected to the dc distribution bus 20. Under the condition that the external alternating current power distribution system supplies power normally, the bidirectional converter module 30 charges the storage battery module 40, so that the storage battery module 40 is in a floating charge state. When the external alternating current power distribution system is abnormal, the storage battery module 40 starts to discharge, and provides direct current for the direct current power distribution bus 20, so that the load on the direct current power distribution bus 20 can work normally.
Under the condition of normal operation of an external alternating current power grid, the storage battery module 40 is always in a floating charging state. And the charging module 10 converts the ac power into dc power, and outputs the dc power to the dc distribution bus 20 to supply power to each dc load. If an excessive impact load demand occurs in the dc power supply system and the charging module 10 cannot supply enough power to remove the impact load energy, the energy required for the impact load is supplied from the battery module 40. If the external alternating current power grid or the charging module 10 has a fault, the charging module 10 stops working, the storage battery module 40 starts to discharge, and direct current is provided for the direct current distribution bus 20, so that the direct current load on the direct current distribution bus 20 can continuously and normally work within a certain time, and the safety of the nuclear power station is guaranteed.
The dc power supply system is connected to the bidirectional converter module 30 through the storage battery module 40, and the bidirectional converter module 30 is connected to the dc distribution bus 20. When the power supply of the power grid is normal, the charging module 10 charges and stores power for the storage battery module 40 through the direct-current distribution bus 20; when the power supply of the power grid is abnormal, the storage battery module 40 reversely supplies power to the direct current distribution bus 20 through the bidirectional converter module 30, so that the direct current load on the direct current distribution bus 20 can work normally, and the safety discharge function of the direct current bus 20 can be effectively realized. And under the condition of abnormal power supply of the power grid, the direct-current load is still ensured to be continuously supplied for a long time, the power utilization requirement of safety-level downstream loads is met, and the safety and the reliability of important loads of the nuclear power station are improved.
In one embodiment, the battery module 40 includes more than two sets of battery packs 401, each battery pack 401 is connected to the bidirectional converter module 30, the battery pack 401 is in a floating state when the external power grid is normally powered, and the battery pack 401 supplies power to the outside through the bidirectional converter module 30 when the power grid 401 is abnormally powered. The battery pack 40 is composed of batteries including, but not limited to, lithium iron phosphate batteries, ternary lithium batteries, and the like. In the present embodiment, battery pack 40 is preferably formed of a lithium iron phosphate battery. Compared with the lead-acid storage battery in the prior art, the storage battery pack 40 formed by the lithium iron phosphate battery has the advantages that the weight is reduced by more than 75%, the occupied area is reduced by more than 80%, and the volume is reduced by more than 65%; and the service life of the storage battery consisting of the lithium iron phosphate battery is more than 15 years, and the cycle life is more than 4000 times, which is more than twice of that of a lead-acid storage battery.
In one embodiment, the bidirectional commutation module 30 includes a bidirectional commutation device 301, and the bidirectional commutation device 301 is coupled to the battery module 40. Specifically, the bidirectional commutation device 301 is connected to the battery pack 401. The bidirectional converter module 30 charges the battery module 40 when the ac power distribution system is supplying power normally.
In one embodiment, the bidirectional converter module 30 further includes a voltage detection device, the voltage detection device is connected to the bidirectional converter device 301 and the dc power distribution bus 20, and the voltage detection device corresponds to the bidirectional converter device 301 one to one, and the voltage detection device monitors the voltage of the dc power distribution bus 20 in real time and controls the on/off of the bidirectional converter device 301.
In one embodiment, if the voltage detection device detects that the voltage of the dc distribution bus 20 is lower than the first voltage value, the voltage detection device controls the bidirectional converter device 301 to open, and the battery module 40 supplies power to the dc distribution bus 20 through the bidirectional converter module 30. And the first voltage value is less than the rated voltage of the dc distribution bus 20. Among the reasons for causing the voltage of the dc distribution bus 20 to drop to the first voltage value include, but are not limited to: the power supply of the external alternating current network is cut off, the charging module is in fault, the direct current distribution bus load is in impact load, the direct current distribution bus load is in severe overload and the like. The first voltage value is usually set to 0.875 times the rated voltage of the dc distribution bus 20, for example, the first voltage value of the dc distribution bus at the rated voltage of 48V is 42V, the first voltage value of the dc distribution bus at the rated voltage of 110V is 96.25V, the first voltage value of the dc distribution bus at the rated voltage of 125V is 109.375V, and the first voltage value of the dc distribution bus at the rated voltage of 230V is 201.25V.
In one embodiment, if the voltage detection device detects that the voltage of the dc distribution bus 20 is greater than or equal to the second voltage value, the voltage detection device controls the bidirectional converter device 301 to turn off, the bidirectional converter module 30 automatically stops supplying power to the dc distribution bus 20, and the storage battery module 40 stops supplying power to the outside. And the second voltage value is the same as the rated voltage of the dc distribution bus 20. When the voltage of the dc distribution bus 20 is greater than or equal to the second voltage value, the external ac power grid is generally recovered to normal power supply, or other abnormal conditions are recovered to normal. The second voltage value is typically set to the nominal voltage value of the dc distribution bus 20, for example, the second voltage value of the dc distribution bus at a nominal voltage of 48V is 48V, the second voltage value of the dc distribution bus at a nominal voltage of 110V is 110V, the second voltage value of the dc distribution bus at a nominal voltage of 125V is 125V, and the second voltage value of the dc distribution bus at a nominal voltage of 230V is 230V. When the charging module loop returns to normal, the bidirectional current conversion module automatically stops supplying power to the direct current distribution bus, and the storage battery module is in a continuous standby state. And when the external power grid power supply is confirmed to be recovered to be normal, the charging module supplements power to the storage battery module.
In one embodiment, if the voltage detection device detects that the voltage of the dc distribution bus 20 is greater than or equal to the second voltage value and lasts for a certain time, the voltage detection device controls the bidirectional converter device 301 to be turned on, and the bidirectional converter module 30 charges the battery module 40. Generally, after a certain time delay, the dc power system confirms that the external ac power grid is restored to normal power supply or other abnormalities are restored to normal, and then the bidirectional converter module 30 starts to charge the storage battery module 40, so as to supplement the discharge capacity of the storage battery module 40. In general, the plurality of times may be set to other required times such as 1 minute, 2 minutes, or 5 minutes. When the voltage of the storage battery module reaches the charging cut-off voltage, the bidirectional current conversion device is closed, the storage battery module finishes charging, and the storage battery module enters a standby state. The charge cutoff voltage of the battery module is usually set to 1.05 times the rated voltage of the battery module. For example, the second voltage value of the dc distribution bus at a rated voltage of 48V is 50.4V, the second voltage value of the dc distribution bus at a rated voltage of 110V is 115.5V, the second voltage value of the dc distribution bus at a rated voltage of 125V is 131.25V, and the second voltage value of the dc distribution bus at a rated voltage of 230V is 241.5V. Particularly, in the charging process of the storage battery module, if the voltage of the direct current distribution bus falls to a first voltage value due to power failure or other abnormal conditions of an external alternating current power grid, the storage battery module immediately ends the charging mode and immediately enters the discharging mode of the storage battery module to supply power to the direct current distribution bus. The bidirectional converter and the storage battery module are matched to switch the charging mode and the discharging mode of the storage battery module, and the switching of the charging mode and the discharging mode of the storage battery module is rapidly realized.
In one embodiment, the bidirectional conversion module is a BUCK-BOOST circuit, and as shown in fig. 2, the bidirectional conversion module is a schematic diagram of the BUCK-BOOST circuit. The bidirectional current conversion module is designed in a staggered parallel mode by using a high-power tube, and high-capacity energy conversion and high-efficiency DC/DC bidirectional energy conversion are realized. The direct-current power supply system uses the BUCK-BOOST circuit, so that the response time of the system can be within several milliseconds, even less than 1 millisecond, the response of the system is basically close to zero second, and the safety discharge function of the direct-current power distribution bus can be effectively realized. Specifically, the BUCK-BOOST circuit is a high-power four-switch BUCK-BOOST circuit.
In one embodiment, the input end of the BUCK-BOOST circuit is connected with the direct current distribution bus, and the output end of the BUCK-BOOST circuit is connected with the storage battery module; when the voltage of the direct current distribution bus is greater than the voltage of the storage battery module, the BUCK-BOOST circuit is in a BOOST circuit boosting mode. Referring to fig. 2, in BOOST mode of the BOOST circuit, the switch Q1 and the switch Q3 are open and conducting. Specifically, in an actual implementation process, the input end may also be an output end, and synchronously, the output end may also be an input end. At this time, the BUCK-BOOST circuit realizes reverse DC/DC energy conversion. Wherein the operation of the respective switches is similar to that described above.
In one embodiment, the input end of the BUCK-BOOST circuit is connected with the direct current distribution bus, the output end of the BUCK-BOOST circuit is connected with the storage battery module, and when the voltage of the direct current distribution bus is smaller than the voltage of the storage battery module, the BUCK-BOOST circuit is in a BUCK mode. Referring to fig. 2, in the BUCK mode of the BUCK circuit, the switch Q2 and the switch Q4 are turned on and turned on. Specifically, in an actual implementation process, the input end may also be an output end, and synchronously, the output end may also be an input end. At this time, the BUCK-BOOST circuit realizes reverse DC/DC energy conversion. Wherein the operation of the respective switches is similar to that described above.
Specifically, in one embodiment, as shown in fig. 3, the dc power supply system includes a charging module 10, a dc distribution bus 20, a bidirectional converter module 30, and a battery module 40. The charging module 10 is respectively connected to an external ac power distribution system and the dc power distribution bus 20, and the charging module 10 is configured to convert ac power input by the external ac power distribution system into dc power for output, so as to supply power to a dc load on the dc power distribution bus 20. The battery module 40 includes a plurality of battery packs 401, and the battery packs 401 are formed of lithium iron phosphate batteries. Correspondingly, the bidirectional commutation module 30 includes a plurality of bidirectional commutation devices 301. The bidirectional commutation devices 301 correspond to the storage battery packs 401 one by one. The storage battery pack 401 is connected with the bidirectional converter device 301, when the external alternating current power distribution system is normal, the bidirectional converter device 301 charges and supplements power to the storage battery pack 401, and when the external alternating current power distribution system is abnormal, the bidirectional converter device 301 is used for outputting energy stored in the storage battery pack 401 to the direct current power distribution bus 20 to uninterruptedly supply power to a direct current load. The direct current power supply system that this embodiment provided can still guarantee that direct current load lasts the power supply for a long time when external alternating current distribution system loses the electricity or charging device power supply is unusual, satisfies security level low reaches load power consumption demand, has improved nuclear power station important load security and reliability.
Specifically, in one embodiment, as shown in fig. 4, the dc power supply system includes a charging module 10, a dc distribution bus 20, a bidirectional converter module 30, and a battery module 40. The charging module 10 is respectively connected to an external ac power distribution system and the dc power distribution bus 20, and the charging module 10 is configured to convert ac power input by the external ac power distribution system into dc power for output, so as to supply power to a dc load on the dc power distribution bus 20. The battery module 40 includes a plurality of battery packs 401, and the battery packs 401 are formed of lithium iron phosphate batteries. And the bidirectional commutation module 30 is a single bidirectional commutation device 301. The bidirectional converter device 301 is connected with a plurality of storage battery packs 401, when the external alternating current power distribution system is normal, the bidirectional converter device 301 charges and supplements power for the storage battery packs 401, and when the external alternating current power distribution system is abnormal, the bidirectional converter device 301 is used for outputting energy stored in the storage battery packs 401 to the direct current power distribution bus 20 to uninterruptedly supply power for direct current loads. The direct current power supply system that this embodiment provided can still guarantee that direct current load lasts the power supply for a long time when external alternating current distribution system loses the electricity or charging device power supply is unusual, satisfies security level low reaches load power consumption demand, has improved nuclear power station important load security and reliability.
Specifically, fig. 5 shows a control logic diagram of the dc power supply system. The bidirectional current conversion module also comprises a voltage detection device, the voltage detection device is connected with the bidirectional current conversion device and the direct current distribution bus, the voltage detection device is in one-to-one correspondence with the bidirectional current conversion device, and the voltage detection device monitors the voltage of the direct current distribution bus in real time and controls the on-off of the bidirectional current conversion device.
If the voltage detection device detects that the voltage of the direct current distribution bus is lower than the first voltage value, the voltage detection device controls the bidirectional current conversion device to be opened, and the storage battery module supplies power to the direct current distribution bus through the bidirectional current conversion module. And the first voltage value is less than the rated voltage of the direct current distribution bus. Reasons for causing the voltage of the dc distribution bus to drop to the first voltage value include, but are not limited to: the power supply of the external alternating current network is cut off, the charging module is in fault, the direct current distribution bus load is in impact load, the direct current distribution bus load is in severe overload and the like. The first voltage value is usually set to 0.875 times the rated voltage of the dc distribution bus, for example, the first voltage value of the dc distribution bus at the rated voltage of 48V is 42V, the first voltage value of the dc distribution bus at the rated voltage of 110V is 96.25V, the first voltage value of the dc distribution bus at the rated voltage of 125V is 109.375V, and the first voltage value of the dc distribution bus at the rated voltage of 230V is 201.25V.
If the voltage detection device detects that the voltage of the direct current distribution bus is larger than or equal to the second voltage value, the voltage detection device controls the bidirectional current conversion device to be closed, the bidirectional current conversion module automatically stops supplying power to the direct current distribution bus, and the storage battery module stops supplying power to the outside. And the second voltage value is the same as the rated voltage of the direct current distribution bus. When the voltage of the direct current distribution bus is larger than or equal to the second voltage value, the external alternating current power grid is recovered to be normal in power supply, or other abnormal conditions are recovered to be normal. The second voltage value is typically set to the dc distribution bus nominal voltage value, for example, 48V for a 48V nominal voltage dc distribution bus, 110V for a 110V nominal voltage dc distribution bus, 125V for a 125V nominal voltage dc distribution bus, and 230V for a 230V nominal voltage dc distribution bus. When the charging module loop returns to normal, the bidirectional current conversion module automatically stops supplying power to the direct current distribution bus, and the storage battery module is in a continuous standby state. And when the external power grid power supply is confirmed to be recovered to be normal, the charging module supplements power to the storage battery module.
Specifically, as shown in fig. 6, a logic diagram of battery pack charging and discharging control of the dc power supply system is shown. In the charging process of the storage battery module, if the voltage of the direct current distribution bus falls to a first voltage value due to power failure or other abnormal conditions of an external alternating current power grid, the storage battery module immediately finishes the charging mode and immediately enters the discharging mode of the storage battery module to supply power to the direct current distribution bus.
And if the voltage of the direct current distribution bus is not changed, the storage battery pack continues to be charged. When the voltage of the storage battery module reaches the charging cut-off voltage, the bidirectional current conversion device is closed, the storage battery module finishes charging, and the storage battery module enters a standby state. The charge cutoff voltage of the battery module is usually set to 1.05 times the rated voltage of the battery module. For example, the second voltage value of the dc distribution bus at a rated voltage of 48V is 50.4V, the second voltage value of the dc distribution bus at a rated voltage of 110V is 115.5V, the second voltage value of the dc distribution bus at a rated voltage of 125V is 131.25V, and the second voltage value of the dc distribution bus at a rated voltage of 230V is 241.5V.
The bidirectional converter and the storage battery module are matched to switch the charging mode and the discharging mode of the storage battery module, and the switching of the charging mode and the discharging mode of the storage battery module is rapidly realized.
In the direct-current power supply system provided by the embodiment, the storage battery pack formed by the lithium iron phosphate battery is used for effectively replacing a lead-acid storage battery pack, and compared with the lead-acid storage battery pack in the prior art, the weight of the storage battery pack formed by the lithium iron phosphate battery is reduced by more than 75%, the occupied area is reduced by more than 80%, and the volume is reduced by more than 65%; and the service life of the storage battery consisting of the lithium iron phosphate battery is more than 15 years, and the cycle life is more than 4000 times, which is more than twice of that of a lead-acid storage battery. Namely, the storage battery consisting of the lithium iron phosphate battery has the characteristics of light weight, small occupied area, small volume, long service life, high safety and the like, and the lithium iron phosphate battery has low cost and is suitable for engineering application and popularization. When the power supply of the power grid is abnormal, the storage battery module reversely supplies power to the direct-current distribution bus through the bidirectional current conversion module, so that the direct-current load on the direct-current distribution bus can work normally, and the safety discharge function of the direct-current bus can be effectively realized. And under the condition of abnormal power supply of the power grid, the direct-current load is still ensured to be continuously supplied for a long time, the power utilization requirement of safety-level downstream loads is met, and the safety and the reliability of important loads of the nuclear power station are improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features of the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A dc power supply system, comprising:
the charging module is externally connected with an alternating current power distribution system and converts alternating current input by the alternating current power distribution system into direct current to be output;
the direct current distribution bus is connected with the charging module and supplies power to a direct current load connected to the direct current distribution bus;
the bidirectional current conversion module is connected with the direct current distribution bus;
and the storage battery module is connected with the bidirectional current conversion module.
2. The dc power supply system of claim 1, wherein the battery modules comprise more than two sets of battery packs, the battery modules providing power to the dc distribution bus when the ac distribution system is de-energized.
3. The dc power supply system of claim 2, wherein the bidirectional converter module comprises a bidirectional converter device, the bidirectional converter device is connected to the battery module, and the bidirectional converter module charges the battery module when the ac power distribution system is supplying power normally.
4. The direct current power supply system according to claim 3, wherein the bidirectional converter module further includes a voltage detection device, the voltage detection device is connected to the bidirectional converter device and the direct current distribution bus, the voltage detection device corresponds to the bidirectional converter device one by one, and the voltage detection device monitors the voltage of the direct current distribution bus in real time and controls on/off of the bidirectional converter device.
5. The direct current power supply system according to claim 4, wherein if the voltage detection device detects that the voltage of the direct current distribution bus is lower than a first voltage value, the voltage detection device controls the bidirectional current conversion device to be opened, and the storage battery module supplies power to the direct current distribution bus through the bidirectional current conversion module; the first voltage value is less than the rated voltage of the direct current distribution bus.
6. The dc power supply system according to claim 5, wherein if the voltage detection device detects that the dc distribution bus voltage is greater than or equal to a second voltage value, the voltage detection device controls the bidirectional converter device to turn off, the bidirectional converter module automatically stops supplying power to the dc distribution bus, and the battery module stops supplying power; the second voltage value is the same as the rated voltage of the direct current distribution bus.
7. The dc power supply system according to claim 6, wherein if the voltage detection device detects that the dc distribution bus voltage is greater than or equal to a second voltage value and lasts for a certain time, the voltage detection device controls the bidirectional converter device to be turned on, and the bidirectional converter module charges the battery module.
8. The DC power supply system of claim 1, wherein the bidirectional converter module is a BUCK-BOOST circuit, and the bidirectional converter module is designed in a staggered parallel mode by using high-power tubes.
9. The dc power supply system of claim 8, wherein an input of the BUCK-BOOST circuit is connected to the dc distribution bus, and an output of the BUCK-BOOST circuit is connected to the battery module; and when the voltage of the direct current distribution bus is greater than the voltage of the storage battery module, the BUCK-BOOST circuit is in a BOOST circuit boosting mode.
10. The dc power supply system of claim 9, wherein the BUCK-BOOST circuit is in BUCK mode when the dc distribution bus voltage is less than the battery module voltage.
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Application publication date: 20210820 |