Compressed air energy storage grid-connected system

Abstract

The utility model discloses a compressed air energy storage grid-connected system, which comprises a compressed air energy storage device, a motor, a compressor, an air storage device, an expansion machine, a generator and a grid-connected switch, the system further comprises a reactive compensation system, a motor voltage transformer, an automatic selection switch, an automatic synchronizing device, a relay, a controller, a power grid voltage transformer, a manual selection switch, a manual synchronizing device and a manual switch, the generator voltage transformer is further connected with the manual selection switch, and the power grid voltage transformer is further connected with the automatic selection switch. According to the utility model, by arranging the generator voltage transformer, the automatic selection switch, the automatic synchronizing device and other components, a user can select a proper grid-connected mode according to the actual situation on site, the operation is flexible, the voltage and frequency of the generator are automatically adjusted, and the grid-connected operation time is reduced. The reactive compensation system provides reactive power for the power generator in the grid-connected process, and the situation that the reactive power is absorbed from a power grid system, and voltage drop is caused is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of power grid regulation, and in particular to a compressed air energy storage grid-connected system. Background Art

[0002] Compressed air energy storage refers to a storage method that uses electrical energy to compress air during the low load period of the power grid, and releases the compressed air during the peak load period to drive the expander to drive the generator to generate electricity. The expansion generator set grid connection refers to the synchronous connection of the generator to the power grid to output electrical energy to the grid.

[0003] Compressed air energy storage is a new type of energy storage technology. The generator grid-connected technology generally adopts quasi-synchronous grid-connected and automatic quasi-synchronous grid-connected.

[0004] Quasi-synchronous grid connection means adjusting the generator excitation before grid connection operation. When the frequency, phase and amplitude of the generator voltage are close to the voltage, frequency, phase and amplitude of the system parallel point, the generator circuit breaker is closed to complete the parallel operation. The biggest advantage of this method is that the impact current is small when connected to the grid.

[0005] Self-synchronous grid connection means that before the grid connection operation, the unexcited generator to be connected is accelerated to the synchronous speed, and then the generator circuit breaker is closed, and then the excitation is added. Under the interaction of the torque of the prime mover and the synchronous torque, the generator is dragged into synchronization. Its biggest advantage is that there is no problem of adjusting the generator voltage and frequency during the grid connection process, the grid connection time is short and the operation is simple.

[0006] At present, the grid-connected methods of compressed air energy storage in the market generally adopt quasi-synchronous grid-connected or self-synchronous grid-connected. Both methods are not considered at the same time, which is not convenient for users to choose according to the actual situation on site and the operation is not flexible. At the same time, the disadvantage of quasi-synchronous grid-connected is that the voltage and frequency of the generator need to be adjusted during the grid-connected operation, the grid-connected time is long and the operation is complicated. In addition, if the closing time is inaccurate, asynchronous closing may occur. The disadvantage of self-synchronous grid-connected is that the grid-connected generator is not excited, and when it is connected to the grid, it will absorb reactive power from the system, causing the system voltage to drop, and at the same time generate a large impact current. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the utility model is to provide a compressed air energy storage grid-connected system to solve the problems that the air energy storage grid-connected system in the prior art is not convenient for users to select according to actual site conditions, is inflexible in operation, and easily causes system voltage to drop, while generating large impact currents.

[0008] In order to solve the above technical problems, the utility model adopts the following technical solutions to achieve the above problems: a compressed air energy storage grid-connected system, including a compressed air energy storage device, wherein the compressed air energy storage device includes a motor, a compressor, an air storage device, an expander, a generator and a grid-connected switch connected in sequence;

[0009] The electric motor is used to receive power from the power grid and drive the compressor to generate high-pressure air which is stored in the air storage device;

[0010] The high-pressure air in the gas storage device drives the expander to drive the generator to generate electricity, and the electric energy generated by the generator enters the power grid through the grid-connected switch;

[0011] The compressed air energy storage grid-connected system also includes a generator voltage transformer and an automatic selection switch connected in sequence;

[0012] The generator voltage transformer is used to monitor the voltage and frequency of the generator;

[0013] The compressed air energy storage grid-connected system further comprises a grid voltage transformer, a manual selection switch, a manual synchronization device and a manual switch connected in sequence, wherein the manual switch is connected to the grid-connected switch;

[0014] The grid voltage transformer is used to monitor the voltage and frequency of the grid;

[0015] The generator voltage transformer is also connected to a manual selection switch, and the grid voltage transformer is also connected to an automatic selection switch.

[0016] The utility model also has the following technical features:

[0017] The automatic selector switch is also connected in sequence to an automatic synchronization device, a relay and a controller;

[0018] The controller comprises an expander speed controller and a generator exciter, wherein the expander speed controller is connected to the expander, and the generator exciter is connected to the generator.

[0019] The relay comprises:

[0020] A speed-up relay connected between the automatic synchronization device and the expander speed controller;

[0021] A speed reduction relay connected between the automatic synchronization device and the expander speed controller;

[0022] A boost relay connected between the automatic synchronization device and the generator exciter;

[0023] A voltage reducing relay connected between the automatic synchronization device and the generator exciter;

[0024] A closing relay connected between the automatic synchronization device and the grid-connected switch.

[0025] The motor is connected to the power grid via a closing switch;

[0026] The grid-connected switch is connected to the power grid via a reactor.

[0027] The motor is connected to the power grid via a closing switch, and the grid-connected switch is connected to the power grid via a reactor.

[0028] The compressed air energy storage grid-connected system also includes a reactive power compensation system, which is used to provide reactive power for the generator during the grid-connected process.

[0029] Compared with the prior art, the utility model has the following technical effects:

[0030] (I) The compressed air energy storage grid-connected system provided by the utility model can meet the needs of users to select a suitable grid-connected mode according to the actual situation on site by setting components such as generator voltage transformer, automatic selection switch, automatic synchronization device, relay, controller, grid voltage transformer, manual selection switch, manual synchronization device and manual switch. The operation is flexible, and the automatic quasi-synchronization device automatically adjusts the generator voltage and frequency to reduce the grid-connected operation time. The reactive power compensation system provides reactive power for the generator during the grid-connected process to avoid absorbing reactive power from the grid system and causing voltage drop.

[0031] (II) The compressed air energy storage grid-connected system provided by the utility model limits the current impact of the power grid on the generator when connected to the grid by setting a reactor.

[0032] (III) The compressed air energy storage grid-connected system provided by the utility model has a simple structure, convenient operation, safety and reliability, and strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall structure of the compressed air energy storage grid-connected system of the utility model.

[0034] The meaning of each symbol in the accompanying drawings:

[0035] 1- compressed air energy storage device, 2- reactive power compensation system, 3- generator voltage transformer, 4- automatic selection switch, 5- automatic synchronization device, 6- relay, 7- controller, 8- grid voltage transformer, 9- manual selection switch, 10- manual synchronization device, 11- manual switch, 12- grid;

[0036] 1-1 motor, 1-2 compressor, 1-3 gas storage device, 1-4 expander, 1-5 generator, 1-6 grid-connected switch, 1-7 closing switch, 1-8 reactor;

[0037] 6-1 speed increase relay, 6-2 speed reduction relay, 6-3 voltage increase relay, 6-4 voltage reduction relay, 6-5 closing relay;

[0038] 7-1 expander speed controller, 7-2 generator exciter.

[0039] The specific contents of the utility model are further explained in detail below in conjunction with the embodiments. DETAILED DESCRIPTION

[0040] All components in the present invention, unless otherwise specified, are components known in the prior art. For example, the reactive power compensation system adopts a known reactive power compensation system. The automatic synchronization device adopts a known automatic synchronization device.

[0041] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of the present application fall within the protection scope of the present invention.

[0042] Embodiment 1:

[0043] This embodiment provides a compressed air energy storage grid-connected system, such as Figure 1 As shown, it includes a compressed air energy storage device 1, and the compressed air energy storage device 1 includes a motor 1-1, a compressor 1-2, an air storage device 1-3, an expander 1-4, a generator 1-5 and a grid-connected switch 1-6 connected in sequence;

[0044] The motor 1-1 is used to receive power from the power grid and drive the compressor 1-2 to generate high-pressure air which is stored in the air storage device 1-3;

[0045] The high-pressure air in the gas storage device 1-3 drives the expander 1-4 to drive the generator 1-5 to generate electricity, and the electric energy generated by the generator 1-5 enters the power grid through the grid-connected switch 1-6;

[0046] The compressed air energy storage grid-connected system further comprises a generator voltage transformer 3 and an automatic selection switch 4 connected in sequence;

[0047] The generator voltage transformer 3 is used to monitor the voltage and frequency of the generators 1-5;

[0048] The compressed air energy storage grid-connected system further comprises a grid voltage transformer 8, a manual selection switch 9, a manual synchronization device 10 and a manual switch 11 connected in sequence, wherein the manual switch 11 is connected to the grid-connected switches 1-6;

[0049] The grid voltage transformer 8 is used to monitor the voltage and frequency of the grid;

[0050] The generator voltage transformer 3 is also connected to a manual selection switch 9 , and the grid voltage transformer 8 is also connected to an automatic selection switch 4 .

[0051] During the period of low electricity prices, the power grid 12 supplies power to the motor 2 through the closing switch 3, and the motor 2 drives the compressor 1 to work to form high-pressure air which is stored in the air storage device 5.

[0052] During the peak electricity price period, the high-pressure air in the gas storage device 5 drives the expander 6 to drive the generator 7 to generate electricity, and the generator 7 is connected to the power grid 12 through the grid-connected switch 8 and the reactor 9.

[0053] During the compressed air energy storage expansion power generation process, the capacitor reactive power compensation device 4 is connected to the power grid 12. When the generator 7 is connected to the power grid 12, the capacitor reactive power compensation device 4 provides reactive current to the generator 7, thereby reducing the reactive current absorbed from the power grid 12 and avoiding the voltage reduction of the power grid 12.

[0054] During the compressed air energy storage process, the capacitor reactive power compensation device 4 is connected to the power grid 12. When the motor 2 starts, the capacitor reactive power compensation device 4 provides reactive current to the motor 2, thereby reducing reactive current absorbed from the power grid 12 and avoiding voltage reduction of the power grid 12.

[0055] As a preferred embodiment of this invention:

[0056] The relay 6 comprises:

[0057] A speed-increasing relay 6-1 connected between the automatic synchronization device 5 and the expander speed controller 7-1;

[0058] A speed reduction relay 6-2 connected between the automatic synchronization device 5 and the expander speed controller 7-1;

[0059] A boost relay 6-3 connected between the automatic synchronization device 5 and the generator exciter 7-2;

[0060] A step-down relay 6-4 connected between the automatic synchronization device 5 and the generator exciter 7-2;

[0061] A closing relay 6-5 is connected between the automatic synchronization device 5 and the grid-connected switch 1-6.

[0062] As a preferred embodiment of this invention:

[0063] The motor 1-1 is connected to the power grid via a closing switch 1-7;

[0064] The grid-connected switch 1-6 is connected to the power grid via the reactor 1-8.

[0065] The function of the reactor 9 is to limit the current impact of the power grid 12 on the generator 7 when the generator 7 is connected to the grid.

[0066] As a preferred embodiment of this invention:

[0067] The compressed air energy storage grid-connected system also includes a reactive power compensation system, which is used to provide reactive power for the generator during the grid-connected process.

[0068] The specific working process of this embodiment is as follows:

[0069] Grid-connected working mode:

[0070] The grid voltage transformer 8 monitors the voltage and frequency of the grid 12 and transmits the voltage and frequency to the automatic synchronization device 5 through the automatic selector switch 4 .

[0071] The grid voltage transformer 8 monitors the voltage and frequency of the grid 12 and transmits the voltage and frequency to the manual synchronization device 10 through the manual selection switch 9.

[0072] The generator voltage transformer 3 monitors the voltage and frequency of the generators 1-5 and transmits them to the automatic synchronization device 5 through the automatic selector switch 4.

[0073] The voltage and frequency of generators 1-5 from generator voltage transformer 3 are transmitted to manual synchronization device 10 through manual selection switch 9.

[0074] When the automatic synchronization device 5 detects that the voltage of the power grid 12 is higher than the voltage of the generator 1-5, it sends a command to the generator exciter 7-2 through the boost relay 6-3, and the generator exciter 7-2 increases the excitation current to increase the voltage at the terminal of the generator 1-5. When the automatic synchronization device 5 detects that the voltage of the power grid 12 is lower than the voltage of the generator 1-5, it sends a command to the generator exciter 7-2 through the step-down relay 6-4, and the generator exciter 7-2 reduces the excitation current to reduce the voltage at the terminal of the generator 1-5.

[0075] When the automatic synchronization device 5 detects that the frequency of the power grid 12 is higher than the frequency of the generator 1-5, it sends a command to the expander speed controller 7-1 through the speed increase relay 6-1, and the expander speed controller 7-1 increases the speed of the expander 1-4. When the automatic synchronization device 5 detects that the frequency of the power grid 12 is lower than the frequency of the generator 1-5, it sends a command to the expander speed controller 7-1 through the speed reduction relay 6-2, and the expander speed controller 7-1 reduces the speed of the expander 1-4.

[0076] When the automatic synchronization device 5 detects that the voltage and frequency difference between the grid 12 and the generator 1-5 meets the grid connection requirement, the automatic synchronization device 5 sends a grid connection signal to the grid connection switch 1-6 through the closing relay 6-5 for closing.

[0077] Manual synchronization device 10 is manually observed. When the voltage and frequency difference between power grid 12 and generator 1-5 meets the grid connection requirement, manual switch 11 is manually operated to send a grid connection signal to grid connection switch 1-6 for closing.

[0078] The above technical solutions are only preferred specific implementation methods of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be thought of by any technician familiar with the field within the technical scope disclosed by the present utility model without creative work are all covered within the protection scope of the present utility model.

Claims

1. A compressed air energy storage grid-connected system, comprising a compressed air energy storage device (1), wherein the compressed air energy storage device (1) comprises an electric motor (1-1), a compressor (1-2), an air storage device (1-3), an expander (1-4), a generator (1-5) and a grid-connected switch (1-6) connected in sequence; The electric motor (1-1) is used to receive power from the power grid and drive the compressor (1-2) to generate high-pressure air which is stored in the air storage device (1-3); The high-pressure air in the gas storage device (1-3) drives the expander (1-4) to drive the generator (1-5) to generate electricity, and the electric energy generated by the generator (1-5) enters the power grid through the grid-connected switch (1-6), characterized in that: The compressed air energy storage grid-connected system further comprises a generator voltage transformer (3) and an automatic selection switch (4) which are connected in sequence; The generator voltage transformer (3) is used to monitor the voltage and frequency of the generator (1-5); The compressed air energy storage grid-connected system further comprises a grid voltage transformer (8), a manual selection switch (9), a manual synchronization device (10) and a manual switch (11) which are connected in sequence, and the manual switch (11) is connected to the grid-connected switch (1-6); The grid voltage transformer (8) is used to monitor the voltage and frequency of the grid; The generator voltage transformer (3) is also connected to a manual selection switch (9), and the grid voltage transformer (8) is also connected to an automatic selection switch (4).

2. The compressed air energy storage grid-connected system according to claim 1, characterized in that: The automatic selector switch (4) is also connected in sequence to an automatic synchronization device (5), a relay (6) and a controller (7); The controller (7) comprises an expander speed controller (7-1) and a generator exciter (7-2), wherein the expander speed controller (7-1) is connected to the expander (1-4), and the generator exciter (7-2) is connected to the generator (1-5).

3. The compressed air energy storage grid-connected system according to claim 2, characterized in that: The relay (6) comprises: A speed-increasing relay (6-1) connected between the automatic synchronization device (5) and the expander speed controller (7-1); A speed reduction relay (6-2) connected between the automatic synchronization device (5) and the expander speed controller (7-1); A boost relay (6-3) connected between the automatic synchronization device (5) and the generator exciter (7-2); A step-down relay (6-4) connected between the automatic synchronization device (5) and the generator exciter (7-2); A closing relay (6-5) is connected between the automatic synchronization device (5) and the grid-connected switch (1-6).

4. The compressed air energy storage grid-connected system according to claim 1, characterized in that: The motor (1-1) is connected to the power grid via a closing switch (1-7), and the grid-connected switch (1-6) is connected to the power grid via a reactor (1-8).

5. The compressed air energy storage grid-connected system according to claim 1, characterized in that: The compressed air energy storage grid-connected system further comprises a reactive power compensation system (2), wherein the reactive power compensation system (2) is used to provide reactive power for the generator during the grid-connected process.

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