Energy storage flywheel array system, braking control method and power grid system

Abstract

The application belongs to the technical field of energy storage flywheel and provides an energy storage flywheel array system, a braking control method and a power grid system. The energy storage flywheel array system comprises a plurality of energy storage flywheel bodies, each of which is connected in series with a machine-side converter; each energy storage flywheel body is further connected with a braking resistor between the corresponding machine-side converter, the braking resistor is controlled by a first relay, the machine-side converter and the energy storage flywheel body are further connected in series with a second relay, and the first relay and the second relay are connected with a controller.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy storage flywheel, and particularly relates to an energy storage flywheel array system, a braking control method and a power grid system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] When the energy storage flywheel is applied to large-scale use, the most commonly used way is parallel array. The traditional energy storage flywheel array system simply connects each energy storage flywheel in parallel from the alternating current side (or in parallel on the direct current bus). Each energy storage flywheel uses a braking resistor alone. In the event of a safety problem such as a fault, the traditional array method generally connects the braking resistor to the direct current side or the flywheel side.

[0004] Therefore, the inventor finds that the traditional energy storage flywheel array system has the following problems: if the brake resistor is connected to the direct current side, when the grid-side converter fails, the energy storage flywheel will not be able to brake, which poses a safety hazard; if the brake resistor is connected to the flywheel side, and the machine-side converter is directly connected to the energy storage flywheel, when the machine-side converter fails, this leads to uncontrollable braking, and only the flywheel back EMF discharges, which is slow. The energy storage capacity and power of the flywheel single unit for energy storage frequency modulation are large. From the aspects of economy and equipment size, the energy storage flywheel single unit cannot be equipped with a large enough power brake resistor to enable fast braking. SUMMARY

[0005] In order to solve the technical problems in the background art, the present application provides an energy storage flywheel array system, a braking control method and a power grid system, which can improve braking efficiency, safety and redundancy.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The first aspect of the present application provides an energy storage flywheel array system, which comprises a plurality of energy storage flywheel bodies, each of which is connected in series with a machine-side converter; each energy storage flywheel body and the corresponding machine-side converter are further connected with a braking resistor, the braking resistor is controlled by a first relay, and the machine-side converter and the energy storage flywheel body are further connected in series with a second relay, and the first relay and the second relay are connected with a controller.

[0008] As an implementation mode, at least two machine-side converters are connected in parallel and then connected in series with a grid-side converter.

[0009] As an implementation mode, all grid-side converters are connected in parallel and then connected to an alternating current grid through a switch cabinet.

[0010] As an implementation form, each of the machine side converters is connected in series with a network side converter.

[0011] As an implementation form, all the network side converters are connected in parallel and connected to an AC power grid through a switch cabinet.

[0012] As an implementation form, when the energy storage flywheel array system is in normal operation, the controller is configured to control the first relays to be in an open state and the second relays to be in a closed state.

[0013] As an implementation form, the controller is further configured to control the first relays connected to the faulty energy storage flywheel body to be switched from an open state to a closed state at a first time, and the first relays corresponding to other normal energy storage flywheel bodies are all closed, and the second relays corresponding to the other normal energy storage flywheel bodies are all open.

[0014] The second aspect of the present application provides a braking control method based on the energy storage flywheel array system as described above, when the energy storage flywheel array system is in normal operation, the first relays are controlled to be in an open state and the second relays are controlled to be in a closed state.

[0015] As an implementation form, when any of the energy storage flywheel bodies fails, the first relays connected to the faulty energy storage flywheel body are controlled to be switched from an open state to a closed state at a first time, and the first relays corresponding to other normal energy storage flywheel bodies are all closed, and the second relays corresponding to the other normal energy storage flywheel bodies are all open.

[0016] The third aspect of the present application provides a power grid system comprising the energy storage flywheel array system as described above.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The present application connects a braking resistor between each energy storage flywheel body and the corresponding machine side converter, and the braking resistor is controlled by the first relays, so that emergency braking can be realized by controlling the corresponding first relays and second relays. The braking resistor of the entire array system is used as a whole, and each flywheel in the system can use the braking resistor of the entire array system at the same time, which not only reduces the usage quota of a single braking resistor, but also ensures that the total braking resistor of the entire system is larger than the single braking resistor in the conventional configuration, thereby greatly improving the braking efficiency and safety and redundancy.

[0019] The advantages of the additional aspects of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The embodiments of the application, and their

[0021] Figure 1 is a schematic diagram of a conventional energy storage flywheel array system structure;

[0022] Figure 2 is a schematic diagram of an energy storage flywheel array system structure of embodiment 1 of the present application;

[0023] Figure 3 is a schematic diagram of a No. 1 energy storage flywheel fault in the energy storage flywheel array system of embodiment 1 of the present application;

[0024] Figure 4 is a schematic diagram of an energy storage flywheel array system structure of embodiment 2 of the present application.

[0025] Wherein, 1. Switch cabinet; 2. Grid-side converter; 3. Machine-side converter; 4. First relay; 5. Brake resistor; 6. Second relay; 7. Energy storage flywheel body; 8. Controller. DETAILED DESCRIPTION

[0026] The application will be further described below in conjunction with the drawings and embodiments.

[0027] It should be noted that the following detailed description is illustrative only, and is intended to provide further description of the application. Unless otherwise defined, 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.

[0028] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0029] A single energy storage flywheel is generally connected to a frequency converter, and then connected to a grid-side converter (PCS) through a switch cabinet, and then connected to an AC power grid. The working principle is as follows: when absorbing electric energy through the power grid, the PCS converts the AC power of the power grid into DC power, and then drives the energy storage flywheel body through the frequency converter to increase the rotational speed of the energy storage flywheel body, and stores the electric energy as the kinetic energy of the rotor; when feeding back energy to the AC power grid, the rotational speed of the energy storage flywheel body is reduced, the kinetic energy is converted into electric energy through the machine-side frequency converter, and the DC power is converted into power frequency AC power through the PCS to feed back to the power grid. In general, the brake resistor is as follows Figure 1The connection shown is on the DC side or flywheel, and controlled by the corresponding relay.

[0030] Example 1

[0031] like Figure 2 As shown, this embodiment provides an energy storage flywheel array system, which includes multiple energy storage flywheel bodies 7, each energy storage flywheel body 7 being connected in series with a machine-side converter 3; each energy storage flywheel body 7 is also connected to a corresponding machine-side converter 3 with a braking resistor 5, the braking resistor 5 being controlled by a first relay 4, and a second relay 6 being connected in series between the machine-side converter 3 and the energy storage flywheel body 7, both the first relay 4 and the second relay 6 being connected to a controller 8.

[0032] In this embodiment, at least two of the generator-side converters 3 are connected in parallel and then connected in series with one grid-side converter 2. All the grid-side converters 2 connected in parallel are then connected to the AC power grid via a switch cabinet 1.

[0033] In the specific implementation process, when the energy storage flywheel array system is working normally, the controller 8 is used to control: the first relay 4 is in the open state and the second relay 6 is in the closed state.

[0034] The controller 8 is also used to control: the first relay 4 connected to the faulty energy storage flywheel body changes from the open state to the closed state at the first time; the first relay 4 corresponding to other normal energy storage flywheel bodies is also closed, and the second relay 6 corresponding to other normal energy storage flywheel bodies is open.

[0035] Example 2

[0036] like Figure 4 As shown, this embodiment differs from Embodiment 1 in that each of the machine-side converters 3 is connected in series with one grid-side converter 2. All the grid-side converters 2 are connected in parallel and then connected to the AC power grid via switchgear 1.

[0037] Example 3

[0038] The braking control process of the energy storage flywheel array system provided in Embodiment 1 or Embodiment 3 above is as follows:

[0039] When the energy storage flywheel array system is working normally, the first relay is in the open state and the second relay is in the closed state.

[0040] When any energy storage flywheel body fails, the first relay connected to the failed energy storage flywheel body immediately changes from the open state to the closed state; the first relays corresponding to other normal energy storage flywheel bodies also close, and the second relays corresponding to other normal energy storage flywheel bodies open.

[0041] Embodiment 4

[0042] The embodiment provides a power grid system, which comprises the energy storage flywheel array system as described in any one of the above-mentioned embodiment 1 or embodiment 2.

[0043] It should be noted that, in the power grid system in the embodiment, other structures can be realized by using existing structures, and details are not described herein.

[0044] The above only provides preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An energy storage flywheel array system, characterized in that, It includes multiple energy storage flywheel bodies, each of which is connected in series with a machine-side converter; each energy storage flywheel body is also connected to the corresponding machine-side converter with a braking resistor, the braking resistor is controlled by a first relay, and the machine-side converter is connected in series with a second relay, both the first and second relays are connected to a controller. At least two of the aforementioned generator-side converters are connected in parallel and then connected in series with one grid-side converter, wherein all of the aforementioned grid-side converters are connected in parallel and then connected to the AC power grid through a switch cabinet; When the energy storage flywheel array system is working normally, the controller is used to control: the first relay is in the open state and the second relay is in the closed state; when any energy storage flywheel body fails, the controller controls the first relay connected to the failed energy storage flywheel body to change from the open state to the closed state at the first time, controls all the first relays corresponding to other normal energy storage flywheel bodies to close, and controls all the second relays corresponding to other normal energy storage flywheel bodies to open. By using the braking resistors of the entire array system as a whole, each flywheel can simultaneously use every braking resistor in the entire array system through system control, reducing the usage quota of a single braking resistor. Moreover, the braking resistors of the entire system are greater than those of a single braking resistor in a traditional configuration, thus improving braking efficiency.

2. The energy storage flywheel array system as described in claim 1, characterized in that, Each of the machine-side converters is connected in series with a grid-side converter.

3. The energy storage flywheel array system as described in claim 2, characterized in that, All the grid-side converters are connected in parallel and then connected to the AC power grid through a switchgear.

4. A braking control method based on an energy storage flywheel array system as described in any one of claims 1-3, characterized in that, When the energy storage flywheel array system is working normally, the first relay is in the open state and the second relay is in the closed state.

5. The braking control method for the energy storage flywheel array system as described in claim 4, characterized in that, When any energy storage flywheel body fails, the first relay connected to the failed energy storage flywheel body immediately changes from the open state to the closed state; the first relays corresponding to other normal energy storage flywheel bodies also close, and the second relays corresponding to other normal energy storage flywheel bodies open.

6. A power grid system, characterized in that, Including the energy storage flywheel array system as described in any one of claims 1-3.

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