Flywheel energy storage device emergency braking energy recovery device based on super capacitor

Abstract

The utility model provides a flywheel energy storage device emergency braking energy recovery device based on a super capacitor, and belongs to the field of energy recovery. The problems that an existing flywheel energy storage device adopts a braking resistor for emergency braking energy absorption, energy loss is serious, the braking speed is low, and potential safety hazards exist are solved. Comprising a super capacitor bank, a double-arm bridge type high-frequency switch, a high-frequency transformer, a double-arm half-bridge driving circuit and an LC filtering voltage limiting circuit, the positive electrode of the super capacitor bank is connected with a fuse and a main switch in series, the other end of the main switch is connected with the positive electrode of the double-arm bridge type high-frequency switch, and the negative electrode of the double-arm bridge type high-frequency switch is connected with the negative electrode of the super capacitor bank. The middle points of two bridge arms of the double-arm bridge type high-frequency switch are connected to the low-voltage side of the high-frequency transformer respectively, the high-voltage side of the high-frequency transformer is connected with the middle points of two bridge arms of the double-arm half-bridge driving circuit respectively, and the positive electrode and the negative electrode of the double-arm half-bridge driving circuit are connected with the two ends of the LC filtering voltage limiting circuit respectively. The flywheel energy storage device is applied to flywheel energy storage devices.

Description

Technical Field

[0001] This invention provides an emergency braking energy recovery device based on a supercapacitor-driven flywheel energy storage device, belonging to the field of emergency braking technology for energy storage devices. Background Technology

[0002] Currently, my country is vigorously developing new power systems with energy storage devices as an important component. Flywheel energy storage devices, due to their high power density, fast response speed, long cycle life, environmental friendliness, and maintenance-free operation, are finding increasingly widespread application in new power systems and the power ancillary services market.

[0003] Flywheel energy storage devices store energy through a high-speed rotating flywheel rotor, which can often reach speeds of 40,000 to 50,000 r / min or higher. Under normal circumstances, when not charging or discharging, the flywheel energy storage device generally maintains a medium speed to achieve a constant idling speed; when in a charging or discharging state, the flywheel energy storage device exchanges energy with the external power grid, and its speed increases or decreases accordingly.

[0004] However, in some special circumstances, such as when the flywheel energy storage device suddenly disconnects from the grid, or when the flywheel energy storage device itself experiences an accident (including internal short circuits, loss of cooling, etc.), it is necessary to brake the flywheel energy storage device urgently to reduce its speed rapidly until it comes to a stop in a short period of time, so as to avoid the high-speed flywheel losing control and posing a threat to the safety of external personnel and equipment.

[0005] Therefore, large-capacity flywheel energy storage devices must be equipped with an energy absorption system for emergency braking to consume the regenerative electrical energy generated during rapid flywheel stopping. This energy absorption system is generally implemented using a braking resistor.

[0006] This approach has the following problems in practice:

[0007] 1) Significant energy loss exists. High-speed rotating flywheel energy storage devices retain a high level of energy. Taking a large flywheel energy storage device with a capacity of 1MW / 12min as an example, when it is fully charged, it is equivalent to holding 200kWh of electricity, which is enough to support an average family of three for a month. If emergency braking is performed using a braking resistor, this energy will ultimately be lost entirely as heat.

[0008] 2) Braking with a braking resistor is relatively slow. Braking with a braking resistor involves short-circuiting the external load in the flywheel circuit during flywheel deceleration. This causes the current in the flywheel motor's circuit to flow through the braking resistor when it stops, generating heat and dissipating the energy used for flywheel deceleration. The energy conversion process is mechanical energy → regenerated electrical energy → heat energy. However, due to the limited heat dissipation capacity of the resistor and the natural diffusion of heat, this method results in a relatively slow energy conversion speed. In emergency situations, it may not meet requirements, leading to adverse consequences.

[0009] 3) There are safety hazards in using braking resistors. When using braking resistors, the resistor will bear a high current and generate heat. If the power of the selected resistor is insufficient or the heat dissipation capacity is inadequate, it may cause the resistor itself to short circuit or even burn out, ultimately leading to secondary accidents.

[0010] Based on the above reasons, a flywheel energy storage device for emergency braking and energy recovery using supercapacitors is proposed. This device avoids the defects of braking resistors during emergency braking of the flywheel device, solves the shortcomings of existing technologies, and realizes energy recovery and reuse, thereby reducing energy consumption and achieving green energy use. Utility Model Content

[0011] To address the problems of severe energy loss, slow braking speed, and safety hazards in existing flywheel energy storage devices that use braking resistors as the energy absorption system for emergency braking, this invention proposes an emergency braking energy recovery device for flywheel energy storage devices based on supercapacitors. The aim is to achieve emergency braking and energy recovery of flywheel energy storage devices by utilizing supercapacitors.

[0012] The technical solution adopted in this utility model is as follows: an emergency braking energy recovery device based on a supercapacitor flywheel energy storage device, wherein the energy recovery device is connected in parallel to the DC bus of the flywheel energy storage device or the flywheel energy storage device group, the DC bus is connected to the output end of the energy storage converter, the input end of the energy storage converter is connected to the mains power, and a circuit breaker is provided on the input bus of the energy storage converter.

[0013] The energy recovery device includes a housing with a cable interface. Inside the housing are an energy recovery circuit board and a control circuit board. The energy recovery circuit board integrates a supercapacitor bank, a double-arm bridge high-frequency switch, a high-frequency transformer, a double-arm half-bridge drive circuit, and an LC filter voltage limiting circuit. The positive terminal of the supercapacitor bank is connected in series with a fuse and a main switch. The other end of the main switch is connected to the positive terminal of the double-arm bridge high-frequency switch, and the negative terminal of the double-arm bridge high-frequency switch is connected to the negative terminal of the supercapacitor bank. The midpoints of the two arms of the double-arm bridge high-frequency switch are respectively connected to the high-frequency transformer. The positive and negative terminals of the low-voltage side of the frequency transformer and the positive and negative terminals of the high-voltage side of the high-frequency transformer are respectively connected to the midpoints of the two arms of the double-arm half-bridge drive circuit. The positive and negative terminals of the double-arm half-bridge drive circuit are respectively connected to the two ends of the LC filter voltage limiting circuit. The LC filter voltage limiting circuit includes an inductor L0 and a capacitor C0. One end of the inductor L0 is connected to the positive terminal of the double-arm half-bridge drive circuit. The other end of the inductor L0 is connected in parallel to one end of the capacitor C0 and the positive terminal of the DC bus. The other end of the capacitor C0 is connected in parallel to the negative terminal of the double-arm half-bridge drive circuit and the negative terminal of the DC bus.

[0014] The control circuit board integrates a microcontroller and a bus current detection circuit. The microcontroller is connected to the main control unit of the main switch and the flywheel energy storage device through wires. The bus current detection circuit is used to detect the real-time current on the DC bus.

[0015] Furthermore, the double-arm bridge high-frequency switch consists of four IGBTs, with a diode and a capacitor connected in anti-parallel across each IGBT.

[0016] Furthermore, the dual-arm half-bridge drive circuit consists of four diodes.

[0017] Furthermore, the power of the energy recovery device is 1.1-1.2 times that of the braking power of the flywheel energy storage device.

[0018] Furthermore, the energy recovery device has a capacity of between 1 / 2 and 3 / 4 of the rated capacity of the flywheel energy storage device.

[0019] Furthermore, the microcontroller uses a single-chip microcomputer.

[0020] The advantages of this utility model over the prior art are as follows:

[0021] (1) This utility model innovatively proposes an emergency braking energy recovery device for flywheel energy storage device using supercapacitor. This device is used to replace the braking resistor in conventional flywheel energy storage device. It can quickly absorb the energy (rotating motor) of the flywheel during emergency braking and convert it into electrical energy for storage. When the flywheel restarts and needs to absorb electrical energy from the outside, it can also release this part of the energy to the flywheel device to realize the recycling of energy and reduce energy consumption.

[0022] (2) The energy recovery circuit with supercapacitor as the main medium can accelerate the energy release speed during emergency braking of the flywheel and avoid the safety hazards of the braking resistor itself.

[0023] (3) The main idea draws on the energy recovery technology that has been applied in the fields of rail transit, etc. The technology is mature and feasible, and it is expected to achieve significant effects of energy saving, emission reduction and equipment efficiency improvement in practice. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings:

[0025] Figure 1 This is a structural block diagram of the device of this utility model used in a flywheel energy storage device;

[0026] Figure 2 This is the main circuit schematic diagram of this utility model;

[0027] In the diagram: 1 is a supercapacitor bank, 2 is a double-arm bridge high-frequency switch, 3 is a high-frequency transformer, 4 is a double-arm half-bridge drive circuit, and 5 is an LC filter voltage limiting circuit. Detailed Implementation

[0028] like Figure 1 and 2 As shown, in order to eliminate the defects that may be caused by using a braking resistor during emergency braking of the flywheel, and at the same time reduce energy consumption and realize energy recycling, this utility model provides an emergency braking energy recovery device for flywheel energy storage based on a supercapacitor. The device is mainly composed of a supercapacitor, which can quickly absorb the energy (rotating motor) of the flywheel during emergency braking and convert it into electrical energy for storage; when the flywheel restarts and needs to absorb electrical energy from the outside, this part of the energy can also be released to the flywheel device, realizing energy recycling and reducing energy consumption.

[0029] Supercapacitors are a new type of energy storage device with high current charging and discharging capabilities, falling between traditional capacitors and secondary batteries. They feature fast charging and discharging speeds, high power density, low energy density, long lifespan, high reliability, and environmental friendliness, making them highly suitable for emergency braking applications using flywheel energy storage devices. Currently, supercapacitors are widely used as power devices or energy storage devices in fields such as rail transportation (e.g., train braking energy recovery) and the military (e.g., electromagnetic railguns), and a considerable number of companies both domestically and internationally are engaged in the design, research and development, and manufacturing of this product. Therefore, there are no significant obstacles in the technology, manufacturing, and application fields for energy recovery devices using supercapacitors as the primary medium, providing a practical feasibility for the realization of this utility model.

[0030] The basic idea of ​​this utility model is to replace the braking resistor by configuring an energy recovery device (including supercapacitor elements, power elements, etc.) with a supercapacitor as the main medium at the DC bus of a large-capacity flywheel energy storage device or energy storage device group. When the flywheel energy storage device or energy storage device group brakes in an emergency, the energy recovery device is activated to release the regenerated electrical energy of the flywheel during braking and to recharge it; when the flywheel energy storage device or energy storage device group starts, the energy recovery device is activated to release the electrical energy stored in the energy recovery device back to the flywheel energy storage device or energy storage device group to help it start up quickly.

[0031] The energy recovery device of this utility model includes a box with a cable interface. An energy recovery circuit board and a control circuit board are installed inside the box. The control circuit board integrates a microcontroller and a bus current detection circuit.

[0032] The main circuit principle of the energy recovery device of this utility model is as follows: Figure 2 As shown, the system includes a supercapacitor bank 1, a double-arm bridge high-frequency switch 2, a high-frequency transformer 3, a double-arm half-bridge drive circuit 4, and an LC filter voltage limiting circuit 5. The supercapacitor bank 1 consists of multiple supercapacitors connected in parallel. A fuse and a main switch are connected in series at the positive terminal of the supercapacitor bank 1. The input Ui is between the main switch and the negative terminal of the supercapacitor bank 1. The input Ui is connected to the double-arm bridge high-frequency switch 2. The double-arm bridge high-frequency switch 2 is connected to the double-arm half-bridge drive circuit 4 through the high-frequency transformer 3. The LC filter voltage limiting circuit 5 is connected to the output terminal of the double-arm half-bridge drive circuit 4. The microcontroller is connected to the main switch and the flywheel energy storage device's main control unit via wires. The bus current detection circuit is used to detect the real-time current on the DC bus.

[0033] The double-arm bridge high-frequency switch 2 consists of four IGBTs (Insulated Gate Bipolar Transistors), labeled A, B, C, and D. Each IGBT has an anti-parallel diode (Da, Db, Dc, Dd) for freewheeling. Each IGBT also has a capacitor (Ca, Cb, Cc, Cd) connected in parallel to absorb voltage spikes during IGBT switching. The double-arm bridge high-frequency switch 2 serves two purposes: as a conventional inverter and as a high-frequency switch for charging and releasing energy.

[0034] The high-frequency transformer 3 is used for voltage isolation and transformation. The primary side of the transformer is connected to the output of the double-arm bridge high-frequency switch 2.

[0035] The dual-arm half-bridge drive circuit 4 consists of four diodes (D1, D2, D3, D4) used to convert AC power into DC power.

[0036] The LC filter voltage limiting circuit 5 consists of an inductor (L0) and a capacitor (C0) for filtering and smoothing the output voltage. The final output is connected to the DC bus of the flywheel energy storage device, and the output voltage is marked as U0.

[0037] This invention enables bidirectional energy flow. When charging is required, energy flows from the input power source to the flywheel energy storage DC busbar; when discharging is required, energy flows from the flywheel energy storage DC busbar to the supercapacitor bank 1.

[0038] The main technical solution of this utility model for an emergency braking energy recovery device using a supercapacitor in a flywheel energy storage system is as follows:

[0039] (1) Determine the characteristic parameters and electrical wiring of a large-capacity flywheel energy storage device or energy storage device group.

[0040] (2) Calculate the power and electricity required for the emergency braking energy recovery device based on the characteristic parameters of the large-capacity flywheel energy storage device or energy storage device group.

[0041] The power P of the energy recovery device is the braking power P of the flywheel energy storage device. z P=P z =k(2πNT) / 60, where k is the proportionality coefficient, which can be taken as 1~1.2 depending on the actual situation; N is the flywheel speed, in r / s; and T is the torque, in N•m.

[0042] The energy recovery device's charge W, based on the characteristics of regenerated electrical energy and considering corresponding losses, is generally taken between 1 / 2 and 3 / 4 of the rated energy of the flywheel energy storage device. The rated energy W of the flywheel energy storage device... f =J•ω 2 / 2, where J is the moment of inertia of the flywheel, in kg•m. 2 ω is the angular velocity of the flywheel, measured in rad / s.

[0043] (3) Select the nominal power and nominal power of the emergency braking energy recovery device. For reliability, the nominal power of the energy recovery device should be selected as 1.1 to 1.2 times the calculated power, and the nominal power can be directly selected according to the calculated power.

[0044] (4) After determining the nominal power of the energy recovery device, match the corresponding high-power transistor GTR and its drive circuit, switching elements, etc. according to the value to realize bidirectional energy exchange with the flywheel device and provide overvoltage protection and other functions.

[0045] (5) Combine supercapacitor elements, bidirectional power elements, etc. to form an energy recovery device, and connect it in parallel to the DC bus of the flywheel energy storage device.

[0046] The specific implementation steps of the energy recovery device of this utility model are as follows:

[0047] (1) Design the supercapacitor components and their parameters according to the flywheel manufacturing data.

[0048] (2) Design a matching bidirectional transducer circuit based on the supercapacitor components and their parameters.

[0049] (3) Design corresponding auxiliary devices (such as radiators, monitoring circuits, etc.).

[0050] (4) Complete the circuit design, system design and manufacturing of the entire energy recovery device.

[0051] (5) Install and conduct joint commissioning tests together with the flywheel energy storage device.

[0052] (6) The product undergoes overall inspection before leaving the factory.

[0053] (7) Transport to the site for installation.

[0054] Regarding the specific structure of this utility model, it should be noted that the connection relationships between the various component modules adopted in this utility model are definite and achievable. Except as specifically described in the embodiments, their specific connection relationships can bring about corresponding technical effects and solve the technical problems proposed by this utility model without relying on the execution of corresponding software programs. The models of the components, modules, and specific components appearing in this utility model, the connection methods between them, and the conventional usage methods and expected technical effects brought about by the above-mentioned technical features, unless specifically described, are all publicly disclosed content in patents, journal articles, technical manuals, technical dictionaries, and textbooks that can be obtained by those skilled in the art before the application date, or belong to conventional technology, common knowledge, and other existing technologies in this field. There is no need to elaborate, which makes the technical solution provided in this case clear, complete, and achievable, and can reproduce or obtain corresponding physical products based on this technical means.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. An emergency braking energy recovery device based on a supercapacitor-driven flywheel energy storage system, characterized in that: The energy recovery device is connected in parallel to the DC bus of the flywheel energy storage device or the flywheel energy storage device group. The DC bus is connected to the output terminal of the energy storage converter. The input terminal of the energy storage converter is connected to the mains power, and a circuit breaker is installed on the input bus of the energy storage converter. The energy recovery device includes a housing with a cable interface. Inside the housing are an energy recovery circuit board and a control circuit board. The energy recovery circuit board integrates a supercapacitor bank, a double-arm bridge high-frequency switch, a high-frequency transformer, a double-arm half-bridge drive circuit, and an LC filter voltage limiting circuit. The positive terminal of the supercapacitor bank is connected in series with a fuse and a main switch. The other end of the main switch is connected to the positive terminal of the double-arm bridge high-frequency switch, and the negative terminal of the double-arm bridge high-frequency switch is connected to the negative terminal of the supercapacitor bank. The midpoints of the two arms of the double-arm bridge high-frequency switch are respectively connected to the high-frequency transformer. The positive and negative terminals of the low-voltage side of the frequency transformer and the positive and negative terminals of the high-voltage side of the high-frequency transformer are respectively connected to the midpoints of the two arms of the double-arm half-bridge drive circuit. The positive and negative terminals of the double-arm half-bridge drive circuit are respectively connected to the two ends of the LC filter voltage limiting circuit. The LC filter voltage limiting circuit includes an inductor L0 and a capacitor C0. One end of the inductor L0 is connected to the positive terminal of the double-arm half-bridge drive circuit. The other end of the inductor L0 is connected in parallel to one end of the capacitor C0 and the positive terminal of the DC bus. The other end of the capacitor C0 is connected in parallel to the negative terminal of the double-arm half-bridge drive circuit and the negative terminal of the DC bus. The control circuit board integrates a microcontroller and a bus current detection circuit. The microcontroller is connected to the main control unit of the main switch and the flywheel energy storage device through wires. The bus current detection circuit is used to detect the real-time current on the DC bus.

2. The emergency braking energy recovery device based on a supercapacitor flywheel energy storage device according to claim 1, characterized in that: The double-arm bridge high-frequency switch consists of four IGBTs, with a diode and a capacitor connected in anti-parallel across each IGBT.

3. The emergency braking energy recovery device based on a supercapacitor flywheel energy storage device according to claim 1, characterized in that: The dual-arm half-bridge drive circuit consists of four diodes.

4. The emergency braking energy recovery device based on a supercapacitor flywheel energy storage device according to claim 1, characterized in that: The power of the energy recovery device is 1.1-1.2 times that of the braking power of the flywheel energy storage device.

5. The emergency braking energy recovery device based on a supercapacitor flywheel energy storage device according to claim 1, characterized in that: The energy recovery device has a capacity of between 1 / 2 and 3 / 4 of the rated capacity of the flywheel energy storage device.

6. The emergency braking energy recovery device based on a supercapacitor flywheel energy storage device according to claim 1, characterized in that: The microcontroller uses a single-chip microcomputer.

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