阅读说明：本技术 基于飞轮的电力调频系统 (Electric power frequency modulation system based on flywheel ) 是由 鄢秋亮 贺智威 李莉 刘�东 柳哲 王亚东 饶武峰 于 2021-07-06 设计创作，主要内容包括：本发明涉及一种基于飞轮的电力调频系统,连接在电网上包括飞轮、双定子电机和变频器；所述飞轮与所述双定子电机的转子传动连接,所述双定子电机的外定子与所述电网通过开关连接；所述双定子电机的内定子通过所述变频器与所述电网连接。本发明提供的基于飞轮的电力调频系统通过将飞轮与双定子电机以及变频器连接,构成一个能够同时进行电力调频和调相的系统,能替代火力发电中的调频机组,很好的利用飞轮储能的大惯量以及快速响应的特点,从电力系统吸收或者释放无功/有功功率,对电网进行稳定的频率调节作用,实现快速调频和调相的同时,还能减少碳排放。(The invention relates to a flywheel-based power frequency modulation system which is connected to a power grid and comprises a flywheel, a double-stator motor and a frequency converter, wherein the flywheel is connected with the power grid through a power line; the flywheel is in transmission connection with a rotor of the double-stator motor, and an outer stator of the double-stator motor is connected with the power grid through a switch; and the inner stator of the double-stator motor is connected with the power grid through the frequency converter. According to the flywheel-based power frequency modulation system, the flywheel is connected with the double-stator motor and the frequency converter to form a system capable of simultaneously carrying out power frequency modulation and phase modulation, a frequency modulation unit in thermal power generation can be replaced, the characteristics of large inertia and quick response of energy storage of the flywheel are well utilized, reactive/active power is absorbed or released from the power system, a stable frequency modulation effect is carried out on a power grid, and carbon emission can be reduced while quick frequency modulation and phase modulation are realized.)

1. A flywheel-based power frequency modulation system is connected to a power grid and is characterized by comprising a flywheel, a double-stator motor and a frequency converter;

the flywheel is in transmission connection with a rotor of the double-stator motor, and an outer stator of the double-stator motor is connected with the power grid through a switch; and the inner stator of the double-stator motor is connected with the power grid through the frequency converter.

2. The flywheel-based power frequency modulation system of claim 1, wherein the frequency converter comprises a machine-side converter, a capacitor and a grid-side converter; the machine side converter is electrically connected with an inner stator of the double-stator motor, and the grid side converter is electrically connected with the power grid; the capacitor is connected in parallel with the machine side converter and the grid side converter respectively.

3. The flywheel-based power frequency modulation system of claim 2, wherein the machine-side converter is an AC/DC rectifier and the grid-side converter is a bi-directional DC/AC converter.

4. The flywheel-based power frequency modulation system according to claim 1, wherein a plurality of first winding slots are uniformly arranged on the circumferential inner side wall of the outer stator, and an outer stator winding is arranged on a slot wall between two adjacent first winding slots.

5. A flywheel-based power FM system as claimed in claim 4, wherein said first winding slot is a fan-shaped slot.

6. The flywheel-based power frequency modulation system according to claim 1, wherein a plurality of second winding slots are circumferentially arranged on the inner stator, the second winding slots comprise a fan-shaped slot body and a rectangular notch, and the fan-shaped slot body is communicated with the outer wall of the inner stator through the rectangular notch; and an inner stator winding is arranged on the groove wall between every two adjacent fan-shaped groove bodies.

7. The flywheel-based electrical frequency modulation system of claim 1, wherein the rotor of the dual stator motor is a nested ring rotor configuration.

Technical Field

The invention relates to the field of power grid equipment, in particular to a flywheel-based power frequency modulation system.

Background

The power grid usually provides electric energy with stable frequency, for example, the rated frequency of the power grid in China is 50Hz, and the frequency stability of the existing power system mainly depends on the original thermal power unit to stabilize the electric frequency. Most of the existing new energy power generation modes, such as wind power generation, photovoltaic power generation and the like, do not have the function of power grid frequency modulation, and the frequency modulation and phase modulation units are separately configured.

The thermal power unit has a good frequency modulation effect, but the response of the thermal power unit is slow, the carbon emission is serious, and a series of environmental problems are easily caused. The new energy power generation has no power grid frequency modulation capability, high-frequency harmonic waves of power electronic devices in a new energy power generation system have negative influence on the stability of the power grid frequency, and a frequency modulation unit generally does not have two functions of frequency modulation and phase modulation at the same time.

In the current power grid system, most frequency modulation units are applied to the frequency modulation of thermal power generation, and the frequency modulation has the environmental problems of slow response, serious carbon emission and the like. The phase modulation unit is composed of a specially designed synchronous phase modulation unit, and the unit mainly provides or absorbs reactive power for a system. Because the frequency modulation unit and the phase modulation unit are operated separately, the frequency modulation unit and the phase modulation unit need to be managed more and more according to the stability requirement of more and more complex power grids, and the equipment cost and the management cost are higher and higher.

Disclosure of Invention

In view of the above, it is desirable to provide a flywheel-based power frequency modulation system that addresses at least one of the above-mentioned problems.

The invention provides a flywheel-based power frequency modulation system which is connected to a power grid and comprises a flywheel, a double-stator motor and a frequency converter;

the flywheel is in transmission connection with a rotor of the double-stator motor, and an outer stator of the double-stator motor is connected with the power grid through a switch; and the inner stator of the double-stator motor is connected with the power grid through the frequency converter.

In one embodiment, the frequency converter comprises a machine side converter, a capacitor and a grid side converter; the machine side converter is electrically connected with an inner stator of the double-stator motor, and the grid side converter is electrically connected with the power grid; the capacitor is connected in parallel with the machine side converter and the grid side converter respectively.

In one embodiment, the machine side converter is an AC/DC rectifier and the grid side converter is a bidirectional DC/AC converter.

In one embodiment, a plurality of first winding slots are uniformly arranged on the circumferential inner side wall of the outer stator, and an outer stator winding is arranged on a slot wall between every two adjacent first winding slots.

In one embodiment, the first winding slot is a fan-shaped slot.

In one embodiment, a plurality of second winding slots are arranged on the circumference of the inner stator, each second winding slot comprises a fan-shaped slot body and a rectangular slot opening, and the fan-shaped slot bodies are communicated with the outer wall of the inner stator through the rectangular slot openings; and an inner stator winding is arranged on the groove wall between every two adjacent fan-shaped groove bodies.

In one embodiment, the rotor of the double stator motor is a nested ring rotor structure.

The technical scheme provided by the embodiment of the invention has the following beneficial technical effects:

according to the flywheel-based power frequency modulation system, the flywheel is connected with the double-stator motor and the frequency converter to form a system capable of simultaneously carrying out power frequency modulation and phase modulation, a frequency modulation unit in thermal power generation can be replaced, the characteristics of large inertia and quick response of energy storage of the flywheel are well utilized, reactive/active power is absorbed or released from the power system, a stable frequency modulation effect is carried out on a power grid, and carbon emission can be reduced while quick frequency modulation and phase modulation are realized.

Additional aspects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a schematic diagram of a connection structure of a flywheel-based power frequency modulation system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a connection structure of a flywheel-based power frequency modulation system according to another embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a flywheel and a dual stator motor according to an embodiment of the present invention;

fig. 4 is a schematic cross-sectional view illustrating a double-stator motor according to an embodiment of the present invention;

fig. 5 is a diagram illustrating a P-f (active-frequency) curve in an embodiment of the present invention.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Possible embodiments of the invention are given in the figures. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein by the accompanying drawings. The embodiments described by way of reference to the drawings are illustrative for the purpose of providing a more thorough understanding of the present disclosure and are not to be construed as limiting the present invention. Furthermore, if a detailed description of known technologies is not necessary for illustrating the features of the present invention, such technical details may be omitted.

It will be understood by those skilled in the relevant art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, the singular forms "a", "an", "the" 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, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It is to be understood that the term "and/or" as used herein is intended to include all or any and all combinations of one or more of the associated listed items.

The technical solution of the present invention and how to solve the above technical problems will be described in detail with specific examples.

The flywheel-based power frequency modulation system provided by the invention is connected to a power grid, and as shown in fig. 1, comprises a flywheel 100, a double-stator motor 200 and a frequency converter 300. Other components or electrical elements are naturally included in the system, such as the mounting bracket of the flywheel 100, including bearings, connecting shafts, etc., as well as the controller and memory of the power fm system.

The flywheel 100 is in transmission connection with a rotor of the double-stator motor 200, and an outer stator 210 of the double-stator motor 200 is connected with a power grid through a switch; the inner stator 230 of the double stator motor 200 is connected to the grid through the frequency converter 300. As shown in fig. 3, the flywheel 100 is connected with the rotor 220 of the double-stator motor 200 through a transmission shaft, and energy of the double-stator motor 200 is transmitted to the flywheel 100 through the transmission shaft, or mechanical energy on the flywheel 100 is transmitted to the double-stator motor 200 to drive the double-stator motor 200 to generate electricity to generate electric energy. The output frequency of the double stator motor 200 is adjusted by the frequency converter 300 so as to match the grid system.

The flywheel-based electric power frequency modulation system organically combines a flywheel energy storage unit with a double-fed technology, can be directly connected to the grid through the outer stator 210 of the double-stator motor 200, can sense whether the power of the electric power system is balanced in real time on line, and enables the inner stator 210 and the outer stator 210 to absorb or release reactive power or active power to the electric power system through control of the frequency converter 300 so as to adjust unbalanced power appearing in a power grid, thereby realizing the functions of frequency modulation and phase modulation of the power grid.

Optionally, in a specific implementation manner of an embodiment of the present application, as shown in fig. 1, the frequency converter 300 includes a machine-side converter, a capacitor, and a grid-side converter; the machine side converter is electrically connected with the inner stator 230 of the double-stator motor 200, and the grid side converter is electrically connected with the power grid; the capacitor is respectively connected with the machine side converter and the network side converter in parallel.

Optionally, in another specific implementation manner of an embodiment of the present application, as shown in fig. 2, the machine-side converter is an AC/DC rectifier, and the grid-side converter is a bidirectional DC/AC converter.

Optionally, in another specific implementation manner of an embodiment of the present invention, as shown in fig. 4, a plurality of first winding slots 211 are uniformly arranged on a circumferential inner side wall of the outer stator 210, and an outer stator winding 212 is arranged on a slot wall between two adjacent first winding slots 211. Alternatively, the first winding slots 211 are sector slots. For example, the number of the first winding slots 211 may be 16, and the number of the outer stator windings 212 may be 16.

Optionally, in a specific implementation manner of another embodiment of the present application, as shown in fig. 4, a plurality of second winding slots 231 are circumferentially arranged on the inner stator 230, each second winding slot 231 includes a sector slot body 231a and a rectangular slot opening 231b, and the sector slot body 231a is communicated with the outer wall of the inner stator 230 through the rectangular slot opening 231 b; an inner stator winding 232 is arranged on the slot wall between two adjacent sector-shaped slots 231 a. For example, the number of the second winding slots 231 is 6, and the number of the inner stator winding 232 is 6.

Alternatively, in a specific implementation manner of an embodiment of the present application, as shown in fig. 4, the rotor 220 of the double-stator motor 200 has a nested ring-type rotor structure. The rotor 220 of the double-stator motor 200 adopts a nested ring type rotor structure, two stators respectively comprise a set of stator windings, the two sets of stator windings are not directly electrically coupled with each other, and the ends of the two sets of stator windingsThe energy of the ports can flow in both directions. Let omega₁、ω₂、ω_rRespectively the current angular frequency of the outer stator winding, the current angular frequency of the inner stator, the mechanical angular frequency of the flywheel and the rotor, p₁、p₂The number of the pole pairs of the outer stator winding and the number of the pole pairs of the inner stator winding are shown as p₁+p₂。

In the starting and accelerating stages, when the flywheel system is started, the control switch S1 of the grid-connected control system of the flywheel-based power frequency modulation system can be controlled to be switched off, and at the moment, the flywheel and the rotor are driven to accelerate by the variable-frequency speed-regulating asynchronous motor until the angular speed omega r of the flywheel and the rotor reaches a preset value.

In the discharge frequency stabilization phase, the angular speed omega of the flywheel and the rotor_rAfter the preset value is reached, the current angle frequency relation is as follows: omega₁＝ω_r(p₁+p₂)-ω₂It can be seen that to enable direct Grid connection with the Grid, ω 1 must be synchronized with the Grid frequency ω_{Electric power}Unity, i.e. presence of ω_{Electric power}＝ω_r(p₁+p₂)-ω₂. By adding a frequency control link in grid-connected control, omega is adjusted₂So that the above equations satisfy the equality relationship. The flywheel and the rotor store a large amount of rotational kinetic energy, so that the flywheel system has an inertia response effect similar to that of a synchronous generator. For example, if the electrical load increases, ω_{Electric power}Has a downward trend and can be reduced by reducing omega₂So that ω of the outer stator of the flywheel system₁Is constantly equal to omega_{Electric power}In the process, the flywheel system feeds power to the power grid.

When the frequency of the power grid rises/falls, after the input/output power of the flywheel 100 is obtained through a P-F droop curve, the inner stator 230 of the flywheel system in the flywheel-based power frequency modulation system provided by the invention is controlled to rapidly act, at the moment, the flywheel and the motor are in sub-synchronous electric operation/super-synchronous power generation operation, the outer stator 210 and the inner stator 230 connected with the power grid absorb/generate power together, and good active support is provided for power grid frequency regulation. The method specifically comprises the following steps:

when the frequency of the power grid rises, according to a P-f (active-frequency) curve shown in fig. 5, the frequency rises at this time, which indicates that the load of the flywheel-based power frequency modulation system is light, the active power Pe of the power grid needs to be reduced, and a control instruction is sent to the flywheel system to enable the double-stator motor 200 to be in sub-synchronous electric operation, so as to drive the flywheel system to accelerate, and the flywheel system absorbs the redundant electric quantity of the power grid, so as to inhibit the further rise of the frequency of the power grid.

When the frequency of the power grid decreases, according to a P-f curve shown in fig. 5, the frequency decreases at this time, which indicates that the load of the flywheel-based power frequency modulation system increases, active power Pe needs to be added to the power grid system, and a control instruction is sent to the flywheel system, so that the double-stator motor 200 is in a super-synchronous power generation operation state, the flywheel system decelerates, the flywheel system provides active power to the power grid, and further decrease of the power grid frequency is suppressed.

Compared with a common double-feed motor, the double-stator motor 200 adopted by the invention comprises two electrical interfaces, each stator comprises one electrical interface, but compared with the common double-feed motor, the magnetic field separation of the inner stator 210 and the outer stator 210 does not have strong coupling, and the decoupling separation can be more conveniently carried out when the motor is controlled, so that the control precision of the whole system is far higher than that of the common double-feed motor, and the robustness of the system is greatly increased.

According to the flywheel-based power frequency modulation system, the flywheel 100 is connected with the double-stator motor 200 and the frequency converter 300 to form a system capable of simultaneously performing power frequency modulation and phase modulation, a frequency modulation unit in thermal power generation can be replaced, the characteristics of large inertia and quick response of energy storage of the flywheel 100 are well utilized, reactive/active power is absorbed or released from a power system, a stable frequency modulation effect is performed on a power grid, and carbon emission can be reduced while quick frequency modulation and phase modulation are realized.

Those of skill in the art will appreciate that the various operations, methods, steps in the processes, acts, or solutions discussed in this application can be interchanged, modified, combined, or eliminated. Further, other steps, measures, or schemes in various operations, methods, or flows that have been discussed in this application can be alternated, altered, rearranged, broken down, combined, or deleted. Further, steps, measures, schemes in the prior art having various operations, methods, procedures disclosed in the present application may also be alternated, modified, rearranged, decomposed, combined, or deleted.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

In the description herein, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is only a partial embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the principle of the present application, and these modifications and decorations should also be regarded as the protection scope of the present application.