Flywheel energy storage variable speed power generation system

Abstract

The flywheel energy storage variable speed power generation system belongs to the field of motors. It solves the problem that the existing flywheel energy storage device is installed on the DC side, resulting in a complex structure of the power generation system, low efficiency and poor reliability. The present invention includes a multi-phase permanent magnet synchronous wind generator, a power converter, an induction motor / generator and an inertial flywheel; when the multi-phase permanent magnet synchronous wind generator has a set of stator windings, the stator winding output end of the multi-phase permanent magnet synchronous wind generator is simultaneously connected to the AC input end of the power converter and the power winding head end of the induction motor / generator, the AC power output from the AC output end of the power converter is connected to the power grid through a transformer, and the rotor of the induction motor / generator is coaxially connected to the inertial flywheel. The present invention is mainly used in wind power generation systems and small hydropower generation systems.

Description

Technical Field

[0001] The invention belongs to the field of motors, and in particular relates to a flywheel energy storage variable speed power generation system. Background Art

[0002] The research on the utilization of renewable energy has been paid attention by all countries today. Wind energy has developed rapidly due to its relatively mature technology and large-scale utilization. However, the randomness and intermittency of wind speed lead to large fluctuations in the grid-connected power of wind farms. With the continuous expansion of wind power, its power fluctuation has an increasingly greater impact on the operational stability and economy of the power grid, and even affects the safe operation of the power grid. Introducing energy storage devices in wind power generation systems can effectively suppress wind power fluctuations, smooth output voltage, and improve power quality. It is a key technology and mainstream method to ensure the grid-connected operation of wind power generation and promote the utilization of wind energy.

[0003] The flywheel system has the advantages of fast charging / discharging speed, high power density, long service life, small impact on the environment, small space occupation, and low requirements for external geographical environment. The use of flywheel system to realize power storage in wind power generation system has broad prospects.

[0004] The role of the flywheel energy storage system in the wind power generation system is as follows: when the flywheel energy storage system is applied to an independently operated wind power generation system, it can quickly emit or absorb active power in the case of wind fluctuations and load disturbances, and achieve a balance between the power emitted and consumed by the wind power system, thereby improving the utilization efficiency of wind energy and the quality of power supply. When it is applied to a grid-connected wind power generation system, by introducing advanced power conversion devices, the flywheel energy storage system can achieve rapid and comprehensive compensation for the active power and reactive power output by the grid-connected wind turbines, thereby effectively reducing the impact of wind speed fluctuations on the power grid and improving the power quality of the power grid containing grid-connected wind turbines.

[0005] At present, there are two main installation locations of flywheel energy storage devices in wind power generation systems: (1) the flywheel energy storage device is installed on the grid-connected side; (2) the flywheel energy storage device is installed on the DC side. The structure diagram of the flywheel energy storage system applied to the grid-connected permanent magnet direct-drive wind power generation system is shown in the figure below. Figure 1 The system consists of a direct-drive wind turbine generator set, a flywheel energy storage system, a power converter, a load, etc., wherein the flywheel energy storage system is connected in parallel to the DC bus.

[0006] Excessive cost is a common problem that limits the widespread application of energy storage technology in wind power generation. Improving energy conversion efficiency and reducing costs are important directions for future research on energy storage technology. Figure 1In the wind power generation system shown, the energy storage motor needs to be connected in parallel to the DC bus through an AC-DC converter (that is, the flywheel energy storage device is installed on the DC side), resulting in high cost, low efficiency, poor reliability and complex control system structure of the power generation system. Therefore, the above problems need to be solved urgently. Summary of the invention

[0007] The purpose of the present invention is to solve the problem that the existing flywheel energy storage device is installed on the DC side, resulting in a complex structure of the power generation system, low efficiency and poor reliability. The present invention provides a flywheel energy storage variable speed power generation system, which has two structures, specifically:

[0008] The first structure:

[0009] A flywheel energy storage variable speed power generation system comprises a multi-phase permanent magnet synchronous wind turbine generator 1, a power converter 2, an induction motor / generator 3 and an inertia flywheel 4;

[0010] The multi-phase permanent magnet synchronous wind turbine generator 1 has a set of stator windings, the stator winding output end of the multi-phase permanent magnet synchronous wind turbine generator 1 is simultaneously connected to the AC input end of the power converter 2 and the power winding head end of the induction motor / generator 3, the AC power output from the AC output end of the power converter 2 is connected to the power grid through a transformer, and the rotor of the induction motor / generator 3 is coaxially connected to the inertia flywheel 4;

[0011] The power converter 2 is used to convert the input AC power into DC power, and then convert the DC power into AC power for output.

[0012] The second structure:

[0013] A flywheel energy storage variable speed power generation system comprises a multi-phase permanent magnet synchronous wind turbine generator 1, a power converter 2, an induction motor / generator 3 and an inertia flywheel 4;

[0014] There are two sets of stator windings on the stator of the multi-phase permanent magnet synchronous wind generator 1. The output end of the first set of stator windings of the multi-phase permanent magnet synchronous wind generator 1 is connected to the AC input end of the power converter 2, and the output end of the second set of stator windings of the multi-phase permanent magnet synchronous wind generator 1 is connected to the head end of the power winding of the induction motor / generator 3. The AC power output from the AC output end of the power converter 2 is connected to the power grid through a transformer, and the rotor of the induction motor / generator 3 is coaxially connected to the inertia flywheel 4;

[0015] The power converter 2 is used to convert the input AC power into DC power, and then convert the DC power into AC power for output.

[0016] For the flywheel energy storage variable speed power generation systems of the above two structures, it is preferred that the stator of the induction motor / generator 3 has two sets of windings, namely the power winding and the excitation winding, and the lead wires of the excitation winding of the induction motor / generator 3 are connected in parallel with a multi-phase capacitor group.

[0017] For the flywheel energy storage variable speed power generation systems of the above two structures, preferably, the head end of the power winding of the induction motor / generator 3 is connected in parallel with a multi-phase capacitor bank.

[0018] For the flywheel energy storage variable speed power generation systems of the above two structures, preferably, the induction motor / generator 3 is a cage rotor induction motor, a solid rotor induction motor, a wound rotor induction motor or a brushless double-fed induction motor.

[0019] For the flywheel energy storage variable speed power generation systems of the above two structures, preferably, there are three implementation modes of the power converter 2:

[0020] The first type: the power converter 2 is implemented by an AC / DC converter 2-1, a capacitor and a DC / AC converter 2-2; the capacitor is arranged between the DC output terminal of the AC / DC converter 2-1 and the DC input terminal of the DC / AC converter 2-2;

[0021] The AC input end of the AC / DC converter 2-1 serves as the AC input end of the power converter 2, and the AC output end of the DC / AC converter 2-2 serves as the AC output end of the power converter 2;

[0022] The second type: the power converter 2 is implemented by an AC-AC converter;

[0023] The third type: the power converter 2 is implemented by an AC-DC-AC converter.

[0024] For the flywheel energy storage variable speed power generation systems of the above two structures, it is preferred that the power output terminal of the rotor of the induction motor / generator 3 is connected to a mechanical load, or is connected to a wind turbine, a water turbine or other power machinery.

[0025] With respect to the flywheel energy storage variable speed power generation system of the second structure described above, preferably, the number of phases of the two sets of stator windings on the stator of the multi-phase permanent magnet synchronous wind generator 1 may be the same or different.

[0026] For the flywheel energy storage variable speed power generation systems of the above two structures, preferably, the power generation system further includes an AC chopper, which is connected to the tail end of the power winding of the induction motor / generator 3.

[0027] The beneficial effects brought by the present invention are:

[0028] The flywheel energy storage variable speed power generation system of the present invention mainly comprises a multi-phase permanent magnet synchronous wind turbine generator 1, a power converter and a motor / generator 3.

[0029] The present invention directly connects the energy storage induction motor / generator 3 to the stator winding output end of the multi-phase permanent magnet synchronous wind generator 1, that is, the present invention directly adds the energy storage induction motor / generator 3 to the AC side of the multi-phase permanent magnet synchronous wind generator 1, eliminating the need for the prior art Figure 1 The AC-DC converter on the motor side of the medium energy storage reduces the capacity of the AC-DC power converter on the output side of the wind turbine, reduces system costs, improves system efficiency, dynamic response and reliability, and simplifies the control system.

[0030] The flywheel energy storage variable speed power generation system of the present invention eliminates the existing Figure 1 The AC-DC converter on the energy storage motor side is converted, and the energy storage motor is directly connected to the AC side, reducing the first-level power conversion. It has the characteristics of high energy conversion efficiency, low cost, long life, high reliability, flexible layout, and easy maintenance. It has good application prospects in wind power generation systems and small hydropower generation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of a permanent magnet direct-drive wind power generation system with a flywheel energy storage device in the prior art;

[0032] Figure 2 It is a structural schematic diagram of the flywheel energy storage variable speed power generation system of the present invention when the multi-phase permanent magnet synchronous wind turbine generator 1 has one set of stator windings;

[0033] Figure 3 It is a structural schematic diagram of the flywheel energy storage variable speed power generation system of the present invention when the multi-phase permanent magnet synchronous wind turbine generator 1 has two sets of stator windings. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0036] Specific implementation method 1: The following is combined Figure 2The present embodiment is described. The flywheel energy storage variable speed power generation system described in the present embodiment comprises a multi-phase permanent magnet synchronous wind turbine generator 1, a power converter 2, an induction motor / generator 3 and an inertia flywheel 4;

[0037] The multi-phase permanent magnet synchronous wind turbine generator 1 has a set of stator windings, the stator winding output end of the multi-phase permanent magnet synchronous wind turbine generator 1 is simultaneously connected to the AC input end of the power converter 2 and the power winding head end of the induction motor / generator 3, the AC power output from the AC output end of the power converter 2 is connected to the power grid through a transformer, and the rotor of the induction motor / generator 3 is coaxially connected to the inertia flywheel 4;

[0038] The power converter 2 is used to convert the input AC power into DC power, and then convert the DC power into AC power for output.

[0039] The present invention directly connects the energy storage induction motor / generator 3 to the stator winding output end of the multi-phase permanent magnet synchronous wind turbine 1, that is, the present invention directly adds the energy storage induction motor / generator 3 to the AC side of the multi-phase permanent magnet synchronous wind turbine 1, thereby eliminating the need for the conventional method. Figure 1 The AC-DC converter on the motor side of the medium energy storage reduces the capacity of the AC-DC power converter on the output side of the wind turbine, reduces system costs, improves system efficiency, dynamic response and reliability, and simplifies the control system.

[0040] In a specific application, when the rotor inertia of the induction motor / generator 3 is large enough, the induction motor / generator 3 may not be connected to the inertia flywheel 4 .

[0041] Specific implementation method 2: The following is combined Figure 3 The present embodiment is described. The flywheel energy storage variable speed power generation system described in the present embodiment comprises a multi-phase permanent magnet synchronous wind turbine generator 1, a power converter 2, an induction motor / generator 3 and an inertia flywheel 4;

[0042] There are two sets of stator windings on the stator of the multi-phase permanent magnet synchronous wind generator 1. The output end of the first set of stator windings of the multi-phase permanent magnet synchronous wind generator 1 is connected to the AC input end of the power converter 2, and the output end of the second set of stator windings of the multi-phase permanent magnet synchronous wind generator 1 is connected to the head end of the power winding of the induction motor / generator 3. The AC power output from the AC output end of the power converter 2 is connected to the power grid through a transformer, and the rotor of the induction motor / generator 3 is coaxially connected to the inertia flywheel 4;

[0043] The power converter 2 is used to convert the input AC power into DC power, and then convert the DC power into AC power for output.

[0044] See also Figure 1 and Figure 3The present invention directly connects the energy storage induction motor / generator 3 to the stator winding output end of the multi-phase permanent magnet synchronous wind generator 1, that is, the present invention directly adds the energy storage induction motor / generator 3 to the AC side of the multi-phase permanent magnet synchronous wind generator 1, thereby eliminating the AC-DC converter on the energy storage motor side in the prior art, reducing the capacity of the AC-DC power converter on the output side of the wind generator, reducing the system cost, improving the system efficiency, dynamic response and reliability, and simplifying the control system.

[0045] This embodiment takes into account that when the rotor inertia of the induction motor / generator 3 is large enough, the induction motor / generator 3 may not be connected to the inertia flywheel 4. It also further takes into account the specific connection of the various components of the flywheel energy storage variable speed power generation system provided when there are two sets of stator windings on the stator of the multi-phase permanent magnet synchronous wind turbine 1.

[0046] In a specific application, when the rotor inertia of the induction motor / generator 3 is large enough, the induction motor / generator 3 may not be connected to the inertia flywheel 4 .

[0047] Specific implementation method three: the following combination Figure 2 and Figure 3 This embodiment is described. This embodiment further describes the first or second embodiment. The stator of the induction motor / generator 3 has two sets of windings, namely a power winding and an excitation winding. The lead wires of the excitation winding of the induction motor / generator 3 are connected in parallel to a multi-phase capacitor group.

[0048] Specific implementation method 4: The following is combined Figure 2 and Figure 3 This embodiment is described. This embodiment further describes the first or second embodiment. The head end of the power winding of the induction motor / generator 3 is connected in parallel with a multi-phase capacitor group.

[0049] Specific implementation method five: the following combination Figure 2 and Figure 3 This embodiment is described. This embodiment further describes the first or second embodiment. The induction motor / generator 3 is a cage rotor induction motor, a solid rotor induction motor, a wound rotor induction motor or a brushless double-fed induction motor.

[0050] Specific implementation method six: the following combination Figure 2 and Figure 3 This embodiment further describes the first or second embodiment. There are three implementation modes of the power converter 2:

[0051] The first type: the power converter 2 is implemented by an AC / DC converter 2-1, a capacitor and a DC / AC converter 2-2; the capacitor is arranged between the DC output terminal of the AC / DC converter 2-1 and the DC input terminal of the DC / AC converter 2-2;

[0052] The AC input end of the AC / DC converter 2-1 serves as the AC input end of the power converter 2, and the AC output end of the DC / AC converter 2-2 serves as the AC output end of the power converter 2;

[0053] The second type: the power converter 2 is implemented by an AC-AC converter;

[0054] The third type: the power converter 2 is implemented by an AC-DC-AC converter.

[0055] In this preferred embodiment, when the power converter 2 is implemented using an AC / DC converter 2-1, a capacitor and a DC / AC converter 2-2, the capacitor between the DC output terminal of the AC / DC converter 2-1 and the DC input terminal of the DC / AC converter 2-2 plays a role in filtering and smoothing.

[0056] Specific implementation method seven: the following combination Figure 2 and Figure 3 This embodiment is described. This embodiment further describes the first or second embodiment. The power output terminal of the rotor of the induction motor / generator 3 is connected to a mechanical load, or is connected to a wind turbine, a water turbine or other power machinery.

[0057] Specific implementation method eight: the following combination Figure 2 and Figure 3 This embodiment is described. This embodiment further describes the second embodiment. The number of phases of the two sets of stator windings on the stator of the multi-phase permanent magnet synchronous wind turbine generator 1 can be the same or different.

[0058] Specific implementation method nine: the following combination Figure 2 and Figure 3 This embodiment is described. This embodiment further describes the first or second embodiment. The power generation system further includes an AC chopper, which is connected to the tail end of the power winding of the induction motor / generator 3.

[0059] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A flywheel energy storage variable speed power generation system, characterized in that: It comprises a multi-phase permanent magnet synchronous wind turbine generator (1), a power converter (2), an induction motor / generator (3) and an inertia flywheel (4); The multi-phase permanent magnet synchronous wind generator (1) has a set of stator windings. The stator winding output end of the multi-phase permanent magnet synchronous wind generator (1) is simultaneously connected to the AC input end of the power converter (2) and the power winding head end of the induction motor / generator (3). The AC power output from the AC output end of the power converter (2) is connected to the power grid through a transformer. The rotor of the induction motor / generator (3) is coaxially connected to the inertia flywheel (4). The power converter (2) is used to convert the input alternating current into direct current, and then convert the direct current into alternating current for output.

2. Flywheel energy storage variable speed power generation system, characterized in that: It comprises a multi-phase permanent magnet synchronous wind turbine generator (1), a power converter (2), an induction motor / generator (3) and an inertia flywheel (4); The stator of the multi-phase permanent magnet synchronous wind generator (1) has two sets of stator windings, the output end of the first set of stator windings of the multi-phase permanent magnet synchronous wind generator (1) is connected to the AC input end of the power converter (2), the output end of the second set of stator windings of the multi-phase permanent magnet synchronous wind generator (1) is connected to the head end of the power winding of the induction motor / generator (3), the AC power output from the AC output end of the power converter (2) is connected to the power grid through a transformer, and the rotor of the induction motor / generator (3) is coaxially connected to the inertia flywheel (4); The power converter (2) is used to convert the input alternating current into direct current, and then convert the direct current into alternating current for output.

3. The flywheel energy storage variable speed power generation system according to claim 1 or 2, characterized in that: The stator of the induction motor / generator (3) has two sets of windings, namely a power winding and an exciting winding. The lead-out wires of the exciting winding of the induction motor / generator (3) are connected in parallel to a multi-phase capacitor group.

4. The flywheel energy storage variable speed power generation system according to claim 1 or 2, characterized in that: The head end of the power winding of the induction motor / generator (3) is connected in parallel to a multi-phase capacitor bank.

5. The flywheel energy storage variable speed power generation system according to claim 1 or 2, characterized in that: The induction motor / generator (3) is a cage rotor induction motor, a solid rotor induction motor, a wound rotor induction motor or a brushless double-fed induction motor.

6. The flywheel energy storage variable speed power generation system according to claim 1 or 2, characterized in that: There are three ways to implement the power converter (2): The first type: the power converter (2) is implemented by using an AC / DC converter (2-1), a capacitor and a DC / AC converter (2-2); the capacitor is arranged between the DC output end of the AC / DC converter (2-1) and the DC input end of the DC / AC converter (2-2); The AC input end of the AC / DC converter (2-1) serves as the AC input end of the power converter (2), and the AC output end of the DC / AC converter (2-2) serves as the AC output end of the power converter (2); The second type: the power converter (2) is implemented using an AC-AC converter; The third type: the power converter (2) is implemented using an AC-DC-AC converter.

7. The flywheel energy storage variable speed power generation system according to claim 1 or 2, characterized in that: The power output terminal of the rotor of the induction motor / generator (3) is connected to a mechanical load, or to a wind turbine, a water turbine or other power machinery.

8. The flywheel energy storage variable speed power generation system according to claim 2, characterized in that: The phase numbers of two sets of stator windings on the stator of the multi-phase permanent magnet synchronous wind generator (1) may be the same or different.

9. The flywheel energy storage variable speed power generation system according to claim 1 or 2, characterized in that: The power generation system also includes an AC chopper, which is connected to the tail end of the power winding of the induction motor / generator (3).

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