CN107706926B - Power grid black start and frequency modulation device and method based on battery pack and liquid air energy storage - Google Patents
Power grid black start and frequency modulation device and method based on battery pack and liquid air energy storage Download PDFInfo
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- CN107706926B CN107706926B CN201710491478.2A CN201710491478A CN107706926B CN 107706926 B CN107706926 B CN 107706926B CN 201710491478 A CN201710491478 A CN 201710491478A CN 107706926 B CN107706926 B CN 107706926B
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
Abstract
The invention discloses a power grid black start and frequency modulation device and method based on a battery pack and liquid air energy storage. The liquid air energy storage and circulation utilizes the valley electricity or the renewable energy generating capacity to obtain the liquid air, and the liquid air is stored in the liquid air storage tank. When the large-area power failure occurs to the power grid, the control unit sends out a black start instruction: the battery pack discharges to start liquid air power generation circulation, and liquid air at the outlet of the liquid air storage tank is pressurized by the booster pump and preheated by the evaporator and then sequentially enters the heaters and the expanders at each stage to be expanded and generated. The generated energy of the liquid air power generation cycle is preferentially used for starting a power plant generator set, power supply of a power grid is recovered, and meanwhile, the generated energy can be supplied to the power plant generator set, so that the capacity requirement on a battery pack is reduced, and the investment and maintenance cost is reduced. In the whole process, the liquid air power generation cycle can be started within 2-5 minutes, so that the power generation set of the power plant can be quickly started to supply power, and the time for restoring the power grid to normal power supply is short. When the power grid has frequency modulation requirements, the control unit sends out a frequency modulation instruction: the battery pack and the liquid air power generation cycle are started simultaneously, the battery pack has high reaction speed and is used for primary frequency modulation, and the liquid air power generation cycle is used for secondary frequency modulation.
Description
Technical Field
The invention relates to a novel power grid black start and frequency modulation system, in particular to a power grid black start and frequency modulation device and method based on a battery pack and liquid air energy storage, and belongs to the technical field of liquid air energy storage, battery energy storage, and power grid black start and frequency modulation.
Background
The stability and accuracy of the power grid frequency are important indexes of power supply quality. Variations and deviations in the grid frequency are well known to have an impact on and a hazard to users and prime movers. The frequency modulation process is also a process for adjusting the energy balance in the power production process. When the frequency of the power grid deviates, the frequency of the power grid is recovered by transferring various energy storage and thermal systems to perform primary frequency modulation (within 30 seconds) and secondary frequency modulation (within 30 seconds to 30 minutes).
The Black Start of the power grid (Black Start) refers to a process of gradually recovering the normal operation of the whole system by starting a unit without self-starting capability in the system through a unit with self-starting capability in the system or externally input power after the power system has a power failure due to a fault. Under the condition of large-area power failure of a power grid, the requirement is that a power supply can be quickly recovered, and if the power supply cannot be recovered within a short time, the national economy suffers huge loss. How to safely and quickly complete system reconstruction after large-area power failure of a system is a key problem to be solved urgently in the power industry all the time.
The liquid air energy storage technology is a cryogenic energy storage technology which utilizes liquid air or nitrogen as an energy storage medium. In the electricity consumption valley period, electric energy is utilized to produce liquid air or liquid nitrogen; under the condition of electricity consumption peak, liquid air or nitrogen is pressurized and heated to drive the expansion machine to do work and generate electricity. The liquid air energy storage system can be started within 2-5 minutes generally, and has the characteristics of high energy storage density, no geographical condition limitation and the like. In addition, the battery energy storage technology has the advantages of short response time (millisecond level), high energy storage density, high energy storage efficiency (85%) and the like, and is widely applied.
According to the analysis, the liquid air energy storage and the battery energy storage have good combinability, and can be used as external power of a power grid, so that the power grid frequency can be quickly recovered, and black start of the power grid can be realized.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a black-start and frequency modulation device and method for a power grid based on a battery pack and liquid air energy storage. The device has two functions of black start and frequency modulation of the power grid: when a large-area power failure occurs to the power grid, the battery pack discharges to start liquid air power generation circulation, so that the power generation set of the power plant is quickly helped to start power supply, and the power supply of the power grid is recovered; when the power grid has frequency modulation requirements, the battery pack and the liquid air power generation cycle are started simultaneously, the battery pack has high reaction speed and is used for primary frequency modulation, and the liquid air power generation cycle is used for secondary frequency modulation.
In order to realize the purpose, the invention adopts the following technical scheme:
the utility model provides a black start of electric wire netting and frequency modulation device based on group battery and liquid air energy storage which characterized in that, the device includes liquid air power generation circulation circuit, liquid air energy storage circulation circuit, group battery, first switch, dc-to-ac converter, second switch, third switch, power plant's generating set, electric wire netting, the control unit and fourth switch, wherein:
the liquid air power generation circulation loop comprises a liquid air storage tank, an air valve, a booster pump, an evaporator, a first-stage heater, a first-stage expansion machine, a second-stage heater, a second-stage expansion machine, a third-stage heater, a third-stage expansion machine, a fourth-stage heater, a fourth-stage expansion machine, a fifth-stage heater, a fifth-stage expansion machine, a first fan, a cold storage tank, a heat storage tank, a first circulating pump, a first valve, a second valve, a third valve, a fourth valve and a fifth valve; the lower output end of the liquid air storage tank is connected with the left input end of the evaporator through an air valve and a booster pump; the right output end of the evaporator is connected with the left input end of the first-stage heater; the right output end of the first-stage heater is connected with the left input end of the second-stage heater through a first-stage expansion machine; the right output end of the second-stage heater is connected with the left input end of the third-stage heater through a second-stage expansion machine; the right output end of the third-stage heater is connected with the left input end of the fourth-stage heater through a third-stage expansion machine; the right output end of the fourth-stage heater is connected with the left input end of the fifth-stage heater through a fourth-stage expansion machine; the right output end of the fifth-stage heater is connected with the lower input end of the evaporator through a fifth-stage expander and a first fan; the lower output end of the evaporator is connected with the lower input end of the cold storage tank; the upper output end of the cold storage tank is connected with the environment; the upper output end of the heat storage tank is divided into five paths through a first circulating pump: one path is connected with the upper input end of the first-stage heater through a first valve; one path is connected with the upper input end of the second-stage heater through a second valve; one path is connected with the upper input end of the third-stage heater through a third valve; one path is connected with the upper input end of the fourth-stage heater through a fourth valve; one path is connected with the upper input end of the fifth-stage heater through a fifth valve; the upper output ends of the first-stage heater, the second-stage heater, the third-stage heater, the fourth-stage heater and the fifth-stage heater are connected in parallel and then connected with the lower input end of the heat storage tank;
the liquid air energy storage circulation loop and the liquid air power generation circulation loop share a liquid air liquid storage tank, a cold storage tank and a heat storage tank, and the liquid air energy storage circulation loop further comprises a first-stage compressor, a first-stage cooler, a second-stage compressor, a second-stage cooler, a cold box, a low-temperature turbine, a second fan and a second circulating pump; the output end of the first-stage compressor is connected with the upper input end of the first-stage cooler; the lower output end of the first-stage cooler is connected with the upper input end of the second-stage cooler through a second-stage compressor; the lower output end of the second-stage cooler is connected with the lower input end of the cold box; the upper output end of the cold box is connected with the left input end of the liquid air storage tank through a low-temperature turbine; the upper output end of the liquid air storage tank is connected with the left input end of the cold box; the left output end of the cold box is connected with the input end of the first-stage compressor; the left output end of the cold storage tank is connected with the right input end of the cold box through a second fan; the right output end of the cold box is connected with the left input end of the cold storage tank; the left side output of heat storage tank is divided into two ways through the second circulating pump: one path is connected with the right input end of the first-stage cooler, and the other path is connected with the right input end of the second-stage cooler; the right output ends of the first-stage cooler and the second-stage cooler are connected in parallel and then are connected with the left input end of the heat storage tank;
the output end of the battery pack is connected with the input end of the inverter through a first switch; the output end of the inverter is respectively connected with the right input end of the air valve, the motor input end of the booster pump, the motor input end of the first fan, the motor input end of the first circulating pump, the right input end of the first valve, the right input end of the second valve, the right input end of the third valve, the right input end of the fourth valve, the right input end of the fifth valve and the left input end of the second switch; the generator output ends of the first stage expander, the second stage expander, the third stage expander, the fourth stage expander and the fifth stage expander are connected in parallel and then divided into three paths: one path is connected with the output end of the inverter in parallel through a second switch; one path is connected with the input end of the power plant generator set through a third switch; one path is connected with the power grid through a fourth switch; the output end of the power plant generator set is connected with a power grid; the control unit sends an instruction to control the operation mode of the device;
preferably, the number of the heaters and the expanders in the liquid air power generation circulation loop can be increased or decreased according to the needs; the number of compressors and coolers in the liquid air energy storage circulation loop can be increased or decreased according to the needs;
further, the control unit may send the instruction by wire or wirelessly.
Specifically, the power grid black start and frequency modulation method based on the battery pack and the liquid air energy storage adopted by the invention comprises the following steps:
the power consumption valley period, the group battery charges, and liquid air energy storage cycle work obtains liquid air simultaneously: the purified air enters a cold box after being compressed by a first-stage compressor, cooled by a first-stage cooler, compressed by a second-stage compressor and cooled by a second-stage cooler, is cooled by normal-pressure low-temperature air flowing back from a liquid air storage tank and low-temperature cold energy stored in a cold storage tank, then enters a low-temperature turbine for expansion and pressure reduction, one part of air is changed into liquid air and is stored in the liquid air storage tank, and the other part of air which is not liquefied enters the first-stage compressor after passing through the cold box; the air compression heat released by the first-stage cooler and the second-stage cooler is stored in the heat storage tank;
when the large-area power failure occurs to the power grid, the control unit sends out a black start instruction: the first switch and the third switch are closed, and the second switch and the fourth switch are opened; the battery pack discharges, and after the battery pack is converted into alternating current through the inverter, the alternating current is supplied to the air valve, the booster pump, the first fan, the first circulating pump, the first valve, the second valve, the third valve, the fourth valve and the fifth valve, and the liquid air power generation cycle is started; the low-temperature liquid air at the outlet of the liquid air storage tank is pressurized by a pressurizing pump, enters an evaporator to exchange heat with the normal-pressure gaseous air at the outlet of a fifth-stage expander, the temperature is increased, the low-temperature liquid air is further heated by a first-stage heater and then enters the first-stage expander to be expanded and generate power, the pressure and the temperature are reduced, the low-temperature liquid air sequentially passes through the heating of a second-stage heater, the expansion and power generation of a second-stage expander, the heating of a third-stage heater, the expansion and power generation of a third-stage expander, the heating of a fourth-stage heater, the expansion and power generation of a fourth-stage expander and the heating of the fifth-stage heater, then enters the fifth-stage expander to be expanded into the normal-pressure gaseous; high-temperature liquid at the outlet of the heat storage tank respectively enters a first-stage heater, a second-stage heater, a third-stage heater, a fourth-stage heater and a fifth-stage heater to be heated before and among stages, so that the expansion work of air is increased; the power generation amount of the first-stage expander, the second-stage expander, the third-stage expander, the fourth-stage expander and the fifth-stage expander is started by a third switch to restore the power generation of the power plant generator set, and the power plant generator set is supplied to a power grid to realize the black start of the power grid;
when the power grid has frequency modulation requirements, the control unit sends out a frequency modulation instruction: the first switch, the second switch and the fourth switch are closed, and the third switch is opened; discharging the battery pack, converting the discharged battery pack into alternating current through an inverter, supplying one part of the alternating current to a power grid for primary frequency modulation, and starting liquid air to generate power for circulation for secondary frequency modulation;
preferably, after the power generating set of the power plant starts generating electricity, the second switch can be closed, so that a part of the generated energy of the liquid air power generation cycle is used for self power supply, and the capacity of the battery pack is reduced; air or nitrogen working medium can be adopted in the liquid air power generation cycle;
furthermore, the cold storage tank can store an external low-temperature cold source, so that the liquefaction rate of the liquid air energy storage circulation is increased; the heat storage tank can store an external high-temperature heat source, and the generated energy of the liquid air power generation cycle is increased.
Compared with the prior art, the invention has the following beneficial effects:
1) the invention utilizes the battery pack to start the liquid air power generation circulation, helps the power plant generator set start power supply, and realizes the black start of the power grid. The battery pack has short discharge response time (millisecond level), the liquid air power generation cycle is completed within 2-5 minutes from starting to normal power generation, the power supply of the power grid can be recovered within a short time, and the national economy is prevented from suffering huge loss.
2) The invention combines the battery pack and the liquid air power generation circulation to realize the frequency modulation of the power grid, wherein the battery pack has high reaction speed and is used for primary frequency modulation, and the liquid air power generation circulation is used for secondary frequency modulation, thereby effectively maintaining the stability and accuracy of the frequency of the power grid and ensuring the power supply quality.
3) In the power grid black start mode, the liquid air power generation cycle can be started within 2-5 minutes, and the required battery pack has small capacity; in addition, a part of the power generation capacity of the liquid air power generation cycle can be used for supplying itself, further reducing the capacity of the battery pack.
4) The invention provides a feasible method and scheme for realizing black start and frequency modulation of the power grid.
Drawings
Fig. 1 is a schematic structural diagram of a black start and frequency modulation apparatus and method for a power grid based on a battery pack and liquid air energy storage according to the present invention;
FIG. 2 is a schematic diagram of the liquid air energy storage cycle of the present invention shown in FIG. 1;
FIG. 3 is a schematic structural diagram of the first embodiment of the present invention shown in FIG. 1;
fig. 4 is a schematic structural diagram of the second embodiment of the present invention shown in fig. 1.
Wherein, the battery pack 1, the first switch 2, the inverter 3, the liquid air storage tank 4, the air valve 5, the booster pump 6, the evaporator 7, the first stage heater 8, the first stage expander 9, the second stage heater 10, the second stage expander 11, the third stage heater 12, the third stage expander 13, the fourth stage heater 14, the fourth stage expander 15, the fifth stage heater 16, the fifth stage expander 17, the first fan 18, the cold storage tank 19, the heat storage tank 20, the first circulation pump 21, the first valve 22, the second valve 23, the third valve 24, the fourth valve 25, the fifth valve 26, the second switch 27, the third switch 28, the power plant generator set 29, the power grid 30, the control unit 31, the fourth switch 32, the first stage compressor 33, the first stage cooler 34, the second stage compressor 35, the second stage cooler 36, the cold box 37, the low temperature turbine 38, the second fan 39, and a second circulation pump 40.
Detailed Description
The invention will now be described with reference to the accompanying drawings. Fig. 1 shows a black start and frequency modulation apparatus and method for a power grid based on a battery pack and liquid air energy storage, the apparatus includes a liquid air power generation circulation loop, a liquid air energy storage circulation loop, a battery pack 1, a first switch 2, an inverter 3, a second switch 27, a third switch 28, a power plant generator set 29, a power grid 30, a control unit 31, and a fourth switch 32, wherein:
the liquid air power generation circulation loop comprises a liquid air storage tank 4, an air valve 5, a booster pump 6, an evaporator 7, a first-stage heater 8, a first-stage expansion machine 9, a second-stage heater 10, a second-stage expansion machine 11, a third-stage heater 12, a third-stage expansion machine 13, a fourth-stage heater 14, a fourth-stage expansion machine 15, a fifth-stage heater 16, a fifth-stage expansion machine 17, a first fan 18, a cold storage tank 19, a heat storage tank 20, a first circulating pump 21, a first valve 22, a second valve 23, a third valve 24, a fourth valve 25 and a fifth valve 26; the lower output end of the liquid air storage tank 4 is connected with the left input end of an evaporator 7 through an air valve 5 and a booster pump 6; the right output end of the evaporator 7 is connected with the left input end of the first-stage heater 8; the right output end of the first-stage heater 8 is connected with the left input end of the second-stage heater 10 through a first-stage expander 9; the right output end of the second-stage heater 10 is connected with the left input end of a third-stage heater 12 through a second-stage expander 11; the right output end of the third stage heater 12 is connected with the left input end of the fourth stage heater 14 through a third stage expansion machine 13; the right output end of the fourth stage heater 14 is connected with the left input end of the fifth stage heater 16 through a fourth stage expansion machine 15; the right output end of the fifth-stage heater 16 is connected with the lower input end of the evaporator 7 through a fifth-stage expander 17 and a first fan 18; the lower output end of the evaporator 7 is connected with the lower input end of the cold storage tank 19; the upper output end of the cold storage tank 19 is connected with the environment; the upper output end of the heat storage tank 20 is divided into five paths by a first circulating pump 21: one path is connected with the upper input end of the first-stage heater 8 through a first valve 22; one path is connected with the upper input end of the second-stage heater 10 through a second valve 23; one path is connected with the upper input end of the third-stage heater 12 through a third valve 24; one path is connected with the upper input end of the fourth-stage heater 14 through a fourth valve 25; one path is connected with the upper input end of the fifth-stage heater 16 through a fifth valve 26; the upper output ends of the first-stage heater 8, the second-stage heater 10, the third-stage heater 12, the fourth-stage heater 14 and the fifth-stage heater 16 are connected in parallel and then connected with the lower input end of the heat storage tank 20;
the liquid air energy storage circulation loop and the liquid air power generation circulation loop share the liquid air storage tank 4, the cold storage tank 19 and the heat storage tank 20, and further comprise a first-stage compressor 33, a first-stage cooler 34, a second-stage compressor 35, a second-stage cooler 36, a cold box 37, a low-temperature turbine 38, a second fan 39 and a second circulation pump 40; the output end of the first stage compressor 33 is connected with the upper input end of the first stage cooler 34; the lower output end of the first stage cooler 34 is connected with the upper input end of the second stage cooler 36 through the second stage compressor 35; the lower output end of the second-stage cooler 36 is connected with the lower input end of the cold box 37; the upper output end of the cold box 37 is connected with the left input end of the liquid air storage tank 4 through a low-temperature turbine 38; the upper output end of the liquid air storage tank 4 is connected with the left input end of the cold box 37; the left output end of the cold box 37 is connected with the input end of the first-stage compressor 33; the left output end of the cold storage tank 19 is connected with the right input end of the cold box 37 through a second fan 39; the right output end of the cold box 37 is connected with the left input end of the cold storage tank 19; the left output end of the heat storage tank 20 is divided into two paths by a second circulating pump 40: one path is connected with the right input end of the first stage cooler 34, and the other path is connected with the right input end of the second stage cooler 36; the right output ends of the first stage cooler 34 and the second stage cooler 36 are connected in parallel and then connected with the left input end of the heat storage tank 20;
the output end of the battery pack 1 is connected with the input end of the inverter 3 through the first switch 2; the output end of the inverter 3 is respectively connected with the right input end of the air valve 5, the motor input end of the booster pump 6, the motor input end of the first fan 18, the motor input end of the first circulating pump 21, the right input end of the first valve 22, the right input end of the second valve 23, the right input end of the third valve 24, the right input end of the fourth valve 25, the right input end of the fifth valve 26 and the left input end of the second switch 27;
the generator output ends of the first stage expander 9, the second stage expander 11, the third stage expander 13, the fourth stage expander 15 and the fifth stage expander 17 are connected in parallel and then divided into three paths: one path is connected with the output end of the inverter 3 in parallel through a second switch 27; one path is connected with the input end of a power plant generating set 29 through a third switch 28; one way is connected with the power grid 30 through a fourth switch 32; the output end of the power plant generator set 29 is connected with a power grid 30; the control unit 31 sends an instruction to control the device operation mode.
A power grid black start and frequency modulation method based on a battery pack and liquid air energy storage comprises the following steps:
with the electricity valley period, group battery 1 charges, and liquid air energy storage cycle work obtains liquid air simultaneously, as shown in fig. 2: the purified air is compressed by the first-stage compressor 33, cooled by the first-stage cooler 34, compressed by the second-stage compressor 35 and cooled by the second-stage cooler 36, enters the cold box 37, is cooled by normal-pressure low-temperature air flowing back from the liquid air storage tank 4 and low-temperature cold energy stored in the cold storage tank 19, then enters the low-temperature turbine 38 for expansion and pressure reduction, one part of air is changed into liquid air and stored in the liquid air storage tank 4, and the other part of air which is not liquefied enters the first-stage compressor 33 after passing through the cold box 37; the heat of compression of the air released from the first stage cooler 34 and the second stage cooler 36 is stored in the heat storage tank 20;
when a large-area power failure occurs in the power grid 30, the control unit 31 sends out a black start instruction, as shown in fig. 3: the first switch 2 and the third switch 28 are closed, the second switch 27 and the fourth switch 32 are open; the battery pack 1 discharges, and after being converted into alternating current by the inverter 3, the alternating current is supplied to the air valve 5, the booster pump 6, the first fan 18, the first circulating pump 21, the first valve 22, the second valve 23, the third valve 24, the fourth valve 25 and the fifth valve 26, and the liquid air power generation cycle is started; the low-temperature liquid air at the outlet of the liquid air storage tank 4 is pressurized by a pressurizing pump 6, enters an evaporator 7 to exchange heat with the normal-pressure gaseous air at the outlet of a fifth-stage expander 17, the temperature is increased, the low-temperature liquid air is further heated by a first-stage heater 8 and then enters a first-stage expander 9 to be expanded and generate power, the pressure and the temperature are reduced, the low-temperature liquid air is heated by a second-stage heater 10, expanded and generated by a second-stage expander 11, heated by a third-stage heater 12, expanded and generated by a third-stage expander 13, heated by a fourth-stage heater 14, expanded and generated by a fourth-stage expander 15 and heated by a fifth-stage heater 16 in sequence, enters the fifth-stage expander 17 to be expanded into the normal-pressure gaseous air, then enters the evaporator 7 to recover the cold energy of the; high-temperature liquid at the outlet of the heat storage tank 20 respectively enters a first-stage heater 8, a second-stage heater 10, a third-stage heater 12, a fourth-stage heater 14 and a fifth-stage heater 16 to be heated before and between stages, so that the expansion work of air is increased; the power generation amounts of the first stage expander 9, the second stage expander 11, the third stage expander 13, the fourth stage expander 15 and the fifth stage expander 17 start a power plant generator set 29 through a third switch 28, so that the power plant generator set is recovered to generate power and is supplied to a power grid 30, and black start of the power grid 30 is realized;
when the grid 30 has a frequency modulation demand, the control unit 31 sends out a frequency modulation command, as shown in fig. 4: the first switch 2, the second switch 27 and the fourth switch 32 are closed, the third switch 28 is open; after the battery pack 1 discharges and is converted into alternating current through the inverter 3, one part of the alternating current is supplied to the power grid 30 for primary frequency modulation, and the other part of the alternating current starts a liquid air power generation cycle for secondary frequency modulation.
For the convenience of understanding the present invention, taking the black start of the power grid in fig. 3 as an example, assuming that the power generation amount of the liquid air power generation cycle is 25MW/100MWh, the temperature of the high temperature liquid in the heat storage tank 20 is 80 ℃, and the temperature of the air heated by the high temperature liquid is 60 ℃. The invention discloses a black-start method of a power grid based on battery pack and liquid air energy storage, which comprises the following steps:
when a large-area power failure occurs in the power grid 30, the battery pack 1 discharges, and after being converted into alternating current by the inverter 3, the alternating current is supplied to the air valve 5, the booster pump 6, the first fan 18, the first circulating pump 21, the first valve 22, the second valve 23, the third valve 24, the fourth valve 25 and the fifth valve 26, so that a liquid air power generation cycle is started; if the liquid air power cycle is started within 5 minutes, the capacity of the stack 1 is only 2.17MW/0.18 MWh;
normal-pressure low-temperature liquid air (-194 ℃) at the outlet of the liquid air storage tank 4 is pressurized to 120bar through a pressurizing pump 6, enters an evaporator 7 to exchange heat with normal-pressure gaseous air at the outlet of a fifth-stage expander 17, the temperature is increased, the normal-pressure low-temperature liquid air is heated to 60 ℃ through a first-stage heater 8, enters a first-stage expander 9 to be expanded and generate power, the pressure is reduced to 48bar, and the temperature is reduced to-15 ℃; heating to 60 deg.C by a second stage heater 10, expanding in a second stage expander 11 to generate power, reducing pressure to 19bar, and reducing temperature to-13 deg.C; heating to 60 ℃ by a third-stage heater 12, entering a third-stage expander 13 for expansion power generation, reducing the pressure to 7.7bar and reducing the temperature to-13 ℃; heating to 60 ℃ by a fourth-stage heater 14, entering a fourth-stage expansion machine 15 for expansion power generation, reducing the pressure to 3.0bar, and reducing the temperature to-12 ℃; heating to 60 ℃ by a fifth-stage heater 16, entering a fifth-stage expander 17 for expansion power generation, reducing the pressure to 1.0bar and the temperature to-23 ℃, then entering an evaporator 7 for recovering the cold energy of low-temperature liquid air, and storing the low-temperature cold energy in a cold storage tank 19; high-temperature liquid (80 ℃) at an outlet of the heat storage tank 20 respectively enters a first-stage heater 8, a second-stage heater 10, a third-stage heater 12, a fourth-stage heater 14 and a fifth-stage heater 16 to be heated before and among stages, and the expansion work of air is increased;
the power generation amount of the first-stage expansion machine 9, the second-stage expansion machine 11, the third-stage expansion machine 13, the fourth-stage expansion machine 15 and the fifth-stage expansion machine 17 starts a power plant generator set 29 to recover power generation and supply the power plant generator set to a power grid 30, so that black start of the power grid 30 is realized; in addition, when the power plant 29 starts generating power, the second switch 27 may be closed to allow a portion of the power generated by the liquid air power cycle to be used for self-power, thereby further reducing the capacity of the battery pack 1.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above embodiment, but equivalent modifications or changes made by those skilled in the art according to the present disclosure should be included in the scope of the present invention as set forth in the appended claims.
Claims (7)
1. The utility model provides a black start of electric wire netting and frequency modulation device based on group battery and liquid air energy storage, its characterized in that, the device includes liquid air power generation circulation circuit, liquid air energy storage circulation circuit, group battery (1), first switch (2), inverter (3), second switch (27), third switch (28), power plant generating set (29), electric wire netting (30), control unit (31) and fourth switch (32), wherein: the liquid air power generation circulation loop comprises a liquid air storage tank (4), an air valve (5), a booster pump (6), an evaporator (7), a first-stage heater (8), a first-stage expansion machine (9), a second-stage heater (10), a second-stage expansion machine (11), a third-stage heater (12), a third-stage expansion machine (13), a fourth-stage heater (14), a fourth-stage expansion machine (15), a fifth-stage heater (16), a fifth-stage expansion machine (17), a first fan (18), a cold storage tank (19), a heat storage tank (20), a first circulating pump (21), a first valve (22), a second valve (23), a third valve (24), a fourth valve (25) and a fifth valve (26); the lower output end of the liquid air storage tank (4) is connected with the left input end of the evaporator (7) through an air valve (5) and a booster pump (6); the right output end of the evaporator (7) is connected with the left input end of the first-stage heater (8); the right output end of the first-stage heater (8) is connected with the left input end of the second-stage heater (10) through a first-stage expansion machine (9); the right output end of the second-stage heater (10) is connected with the left input end of the third-stage heater (12) through a second-stage expansion machine (11); the right output end of the third-stage heater (12) is connected with the left input end of the fourth-stage heater (14) through a third-stage expansion machine (13); the right output end of the fourth-stage heater (14) is connected with the left input end of the fifth-stage heater (16) through a fourth-stage expansion machine (15); the right output end of the fifth-stage heater (16) is connected with the lower input end of the evaporator (7) through a fifth-stage expander (17) and a first fan (18); the lower output end of the evaporator (7) is connected with the lower input end of the cold storage tank (19); the upper output end of the cold storage tank (19) is connected with the environment; the upper output end of the heat storage tank (20) is divided into five paths through a first circulating pump (21): one path is connected with the upper input end of the first-stage heater (8) through a first valve (22); one path is connected with the upper input end of the second-stage heater (10) through a second valve (23); one path is connected with the upper input end of the third-stage heater (12) through a third valve (24); one path is connected with the upper input end of the fourth-stage heater (14) through a fourth valve (25); one path is connected with the upper input end of the fifth-stage heater (16) through a fifth valve (26); the upper output ends of the first-stage heater (8), the second-stage heater (10), the third-stage heater (12), the fourth-stage heater (14) and the fifth-stage heater (16) are connected in parallel and then are connected with the lower input end of the heat storage tank (20); the liquid air energy storage circulation loop and the liquid air power generation circulation loop share a liquid air liquid storage tank (4), a cold storage tank (19) and a heat storage tank (20), and the liquid air energy storage circulation loop and the liquid air power generation circulation loop further comprise a first-stage compressor (33), a first-stage cooler (34), a second-stage compressor (35), a second-stage cooler (36), a cold box (37), a low-temperature turbine (38), a second fan (39) and a second circulation pump (40); the output end of the first-stage compressor (33) is connected with the upper input end of the first-stage cooler (34); the lower output end of the first-stage cooler (34) is connected with the upper input end of the second-stage cooler (36) through a second-stage compressor (35); the lower output end of the second-stage cooler (36) is connected with the lower input end of the cold box (37); the upper output end of the cold box (37) is connected with the left input end of the liquid air storage tank (4) through a low-temperature turbine (38); the upper output end of the liquid air storage tank (4) is connected with the left input end of the cold box (37); the left output end of the cold box (37) is connected with the input end of the first-stage compressor (33); the left output end of the cold storage tank (19) is connected with the right input end of the cold box (37) through a second fan (39); the right output end of the cold box (37) is connected with the left input end of the cold storage tank (19); the left output end of the heat storage tank (20) is divided into two paths through a second circulating pump (40): one path is connected with the right input end of the first-stage cooler (34), and the other path is connected with the right input end of the second-stage cooler (36); the right output ends of the first-stage cooler (34) and the second-stage cooler (36) are connected in parallel and then are connected with the left input end of the heat storage tank (20); the output end of the battery pack (1) is connected with the input end of the inverter (3) through the first switch (2); the output end of the inverter (3) is respectively connected with the right input end of the air valve (5), the motor input end of the booster pump (6), the motor input end of the first fan (18), the motor input end of the first circulating pump (21), the right input end of the first valve (22), the right input end of the second valve (23), the right input end of the third valve (24), the right input end of the fourth valve (25), the right input end of the fifth valve (26) and the left input end of the second switch (27); the generator output ends of the first stage expander (9), the second stage expander (11), the third stage expander (13), the fourth stage expander (15) and the fifth stage expander (17) are connected in parallel and then divided into three paths: one path is connected with the output end of the inverter (3) in parallel through a second switch (27); one path is connected with the input end of a power plant generating set (29) through a third switch (28); one path is connected with the power grid (30) through a fourth switch (32); the output end of the power plant generating set (29) is connected with a power grid (30); the control unit (31) sends an instruction to control the operation mode of the device; the number of heaters, expanders, compressors and coolers in the liquid air power generation cycle can be increased or decreased as desired.
2. A black start and frequency modulation device based on battery pack and liquid air energy storage for power grid according to claim 1, characterized in that the control unit (31) can send command by wire or wirelessly.
3. A black start and frequency modulation method of a power grid based on a battery pack and liquid air energy storage is characterized in that the black start and frequency modulation device of the power grid based on the battery pack and the liquid air energy storage, which is used by the method of claim 1, comprises the following steps: the power consumption valley period, group battery (1) charge, and liquid air energy storage cycle work obtains liquid air simultaneously: the purified air is compressed by a first-stage compressor (33), cooled by a first-stage cooler (34), compressed by a second-stage compressor (35) and cooled by a second-stage cooler (36), then enters a cold box (37), is cooled by normal-pressure low-temperature air flowing back from a liquid air storage tank (4) and low-temperature cold energy stored in a cold storage tank (19), then enters a low-temperature turbine (38) for expansion and pressure reduction, one part of air is changed into liquid air and stored in the liquid air storage tank (4), and the other part of non-liquefied air enters the first-stage compressor (33) after passing through the cold box (37); the air compression heat released by the first-stage cooler (34) and the second-stage cooler (36) is stored in the heat storage tank (20); when a large-area power failure occurs in the power grid (30), the control unit (31) sends out a black start instruction: the first switch (2) and the third switch (28) are closed, and the second switch (27) and the fourth switch (32) are opened; the battery pack (1) discharges, and after the battery pack is converted into alternating current through the inverter (3), the alternating current is supplied to the air valve (5), the booster pump (6), the first fan (18), the first circulating pump (21), the first valve (22), the second valve (23), the third valve (24), the fourth valve (25) and the fifth valve (26), and liquid air power generation circulation is started; after the low-temperature liquid air at the outlet of the liquid air storage tank (4) is pressurized by the booster pump (6), the heat exchange between the normal pressure gas air entering the evaporator (7) and the outlet of the fifth stage expander (17) is carried out, the temperature is increased, after the normal pressure gas air is further heated by the first stage heater (8), enters a first-stage expander (9) for expansion power generation, the pressure and the temperature are reduced, and the gas enters a fifth-stage expander (17) for expansion into normal-pressure gaseous air after being sequentially heated by a second-stage heater (10), a second-stage expander (11) for expansion power generation, a third-stage heater (12), a third-stage expander (13) for expansion power generation, a fourth-stage heater (14), a fourth-stage expander (15) for expansion power generation and a fifth-stage heater (16), then the cold energy enters an evaporator (7) to recover the cold energy of the low-temperature liquid air, and the low-temperature cold energy is stored in a cold storage tank (19); high-temperature liquid at the outlet of the heat storage tank (20) respectively enters a first-stage heater (8), a second-stage heater (10), a third-stage heater (12), a fourth-stage heater (14) and a fifth-stage heater (16) to be heated before and between stages, so that the expansion work of air is increased; the power generation amounts of the first-stage expander (9), the second-stage expander (11), the third-stage expander (13), the fourth-stage expander (15) and the fifth-stage expander (17) start a power plant generator set (29) through a third switch (28) to recover power generation, and the power plant generator set is supplied to a power grid (30) to realize black start of the power grid (30); when the power grid (30) has a frequency modulation demand, the control unit (31) sends out a frequency modulation command: the first switch (2), the second switch (27) and the fourth switch (32) are closed, and the third switch (28) is opened; the battery pack (1) discharges, after the battery pack is converted into alternating current through the inverter (3), one part of the alternating current is supplied to the power grid (30) for primary frequency modulation, and the other part of the alternating current is used for secondary frequency modulation by starting a liquid air power generation cycle.
4. The black start and frequency modulation method for the power grid based on the battery pack and the liquid air energy storage according to claim 3, characterized in that after the power plant generator set (29) starts to generate power, the second switch (27) can be closed, so that a part of the power generation amount of the liquid air power generation cycle is used for self power supply, thereby reducing the capacity of the battery pack (1).
5. The battery pack and liquid air energy storage based power grid black start and frequency modulation method according to claim 3, wherein air or nitrogen working medium can be adopted in the liquid air power generation cycle.
6. The black start and frequency modulation method for the power grid based on the battery pack and the liquid air energy storage is characterized in that the cold storage tank (19) can store an external low-temperature cold source, and the efficiency of the liquid air energy storage circulation is increased.
7. The black start and frequency modulation method for the power grid based on the battery pack and the liquid air energy storage according to claim 3, wherein the heat storage tank (20) can store an external high-temperature heat source to increase the power generation amount of the liquid air power generation cycle.
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| CN112234634B (en) * | 2020-10-19 | 2022-01-28 | 中国科学院理化技术研究所 | Hybrid energy storage power generation system and method |
| CN114123524B (en) * | 2022-01-26 | 2022-05-24 | 百穰新能源科技(深圳)有限公司 | Composite energy storage system and control method thereof |
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