Integrated variable speed phase modulator system

Abstract

This application relates to the field of power frequency modulation technology, and more particularly, to an integrated variable speed phase modulator system. The integrated variable speed phase modulator system includes a step-up transformer suitable for line connection to a power system; a variable frequency current converter connected to the step-up transformer via a line; and a variable speed phase modulator having a current input terminal, an AC rotor, and a current output terminal, the current input terminal being connected to the variable frequency current converter via a line, the current output terminal being connected to the step-up transformer via a line, the AC rotor having a flywheel at each coaxial end, the variable frequency current converter receiving power from the step-up transformer, converting the power into a variable frequency low-frequency AC power, and outputting the converted power to the current input terminal. The AC rotor drives the flywheel to rotate, adjusting the moment of inertia of the rotating AC rotor so that the frequency of the power generated by the variable speed phase modulator is the same as that of the power system, and the current output terminal is input to the power system via the step-up transformer. This application solves the problem that phase modulators can only adjust dynamic voltage regulation and reactive power regulation.

Description

[Technical Field]

[0001] This application relates to the field of power frequency modulation technology, and more particularly to an integrated variable speed phase modulator system. [Background technology]

[0002] According to GB40594-2021 Technical Guidelines for Coordination of Power Grids and Power Sources for Power Systems, current wind power plants and solar power plants, when connected to a power system, must be capable of participating in the power system's primary frequency modulation and dynamic voltage support, while also being capable of moment of inertia support. Therefore, when connected to a power system, wind power plants and solar power plants, which are new energy stations, must provide voltage support by configuring static var generators (SVGs) or static var compensators (SVCs), or use phase modulators to provide dynamic voltage support and moment of inertia support, and must provide primary frequency modulation by configuring energy storage plants such as electrochemical energy storage plants and pumped storage energy storage plants.

[0003] Primary frequency control (PFC) refers to a control function in which, when the frequency of a power system deviates from the target frequency, the power supply adjusts the active power output through an automatic response by the control system to reduce the frequency deviation.

[0004] A conventional phase modulator system mainly consists of a phase modulator, an excitation system, a static variable frequency starter (SFC), and a step-up transformer. Its operation process is that when the voltage of the power system is too high or too low, the excitation system increases or decreases the excitation current of the phase modulator, thereby changing the output voltage of the stator of the phase modulator, thereby realizing voltage regulation and reactive power regulation of the power system by the phase modulator.

[0005] When the phase modulator starts, the static variable frequency starter (SFC) causes a starting current to flow through the stator and rotor of the phase modulator, and the rotor of the phase modulator is affected by the stator current, inducing an electric torque and dragging the rotational speed of the phase modulator from zero to the rated rotational speed.After that, the excitation system causes the operating voltage of the phase modulator to reach the rated value, and after satisfying the grid connection conditions, grid connection with the power system is realized.The rotor of the existing phase modulator configuration consists of two stages, positive and negative, and the operating speed can only be synchronized with the power grid, and only has dynamic voltage regulation and reactive power regulation capabilities. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the technical problem to be solved by the present application is to provide an integrated variable speed phase modulator system to overcome the drawback that the phase modulator in the prior art can only perform dynamic voltage regulation and reactive power regulation. [Means for solving the problem]

[0007] In order to solve the above problems, the present application provides an integrated variable speed phase modulator system, which comprises: a step-up transformer suitable for line connection to a power system; a variable frequency current transformer connected in line to the step-up transformer; a variable speed phase modulator having a current input terminal, an AC rotor, and a current output terminal, the current input terminal being connected to a variable frequency current converter by a line, the current output terminal being connected to a step-up transformer by a line, a flywheel being provided at each coaxial end of the AC rotor, the variable frequency current converter receiving power from the step-up transformer, adjusting the power to a variable frequency low frequency AC power supply and outputting it to the current input terminal, the AC rotor driving and rotating the flywheel to adjust the moment of inertia of the rotating AC rotor, so that the frequency of the power supply generated by the variable speed phase modulator becomes the same as the frequency of the power system, and the power supply is input from the current output terminal via the step-up transformer to the power system.

[0008] Optionally, the step-up transformer has a low voltage side that is connected in line to a variable frequency converter.

[0009] Optionally, the step-up transformer is further provided with a high voltage side that is line connected to the current output terminal.

[0010] Optionally, the frequency of the AC power supply is 50 Hz.

[0011] Optionally, the AC rotor has three phases: U, V, and W.

[0012] Optionally, the variable speed phase modulator further includes a stator.

[0013] Optionally, the power supply further comprises a capacitor connected in line with the step-up transformer.

[0014] Optionally, a reactive power compensator is further included. [Effects of the Invention]

[0015] The technical solution of the present application has the following advantages: 1. The integrated variable speed phase modulator system provided herein includes: a step-up transformer suitable for line connection to a power system; a variable frequency current converter connected to the step-up transformer by a line; and a variable speed phase modulator having a current input terminal, an AC rotor, and a current output terminal, wherein the current input terminal is connected to the variable frequency current converter by a line and the current output terminal is connected to the step-up transformer by a line, and a flywheel is provided on each coaxial end of the AC rotor, the variable frequency current converter receives power from the step-up transformer and converts the power into a variable frequency, low frequency AC power which is output to the current input terminal, and the AC rotor drives the flywheel to rotate, thereby adjusting the moment of inertia of the rotating AC rotor so that the frequency of the power generated by the variable speed phase modulator is the same as the frequency of the power system, and the current output terminal is input to the power system via the step-up transformer. By adjusting the moment of inertia of the AC rotor, the frequency of the variable speed phase modulator becomes the same as the frequency of the power system, and it has frequency modulation capability, thereby solving the problem that only dynamic voltage regulation and reactive power regulation can be performed.

[0016] 2. In the integrated variable speed phase modulator system provided herein, a step-up transformer has a low voltage side connected in line to a variable frequency current converter, which obtains operating power from the low voltage side, and the variable frequency current converter conditions the power to a variable frequency low frequency AC power supply and delivers it to the current input terminals of the variable speed phase modulator.

[0017] 3. In the integrated variable speed phase modulator system provided herein, the step-up transformer is further provided with a high voltage side connected to the current output terminal by a line, and the current output through the current output terminal is transported to the power system via the step-up transformer.

[0018] 4. In the integrated variable speed phase modulator system provided in this application, the AC rotor has three phases, U, V, and W, and the three-phase AC rotor controls its own rotation speed.

[0019] 5. The integrated variable speed phase modulator system provided herein further comprises a capacitor, which is connected in line to the step-up transformer to compensate for or absorb active power on the low voltage side of the step-up transformer.

[0020] 6. The integrated variable speed phase modulator system provided herein further comprises a reactive power compensator and is regulated by the reactive power compensator. [Brief explanation of the drawings]

[0021] In order to more clearly describe the specific embodiments of the present application or the technical solutions of the prior art, the following briefly introduces drawings necessary for describing the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without any creative efforts.

[0022] [Figure 1] 1 is a schematic diagram of an integrated variable speed phase modulator system provided in an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0023] The technical solutions of the present application will be described below clearly and completely in conjunction with the drawings, but it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. Based on the embodiments of the present application, other embodiments that a person skilled in the art can obtain without any creative efforts all belong to the protection scope of the present application.

[0024] In the description of this application, orientations or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "lateral," "inner," and "outer" are orientations or positional relationships indicated based on the drawings, and are intended only to facilitate and simplify the description of this application, and are not intended to indicate or imply that the devices or elements referred to necessarily have a specific orientation or are constructed and operated in a specific orientation, and therefore should not be understood to limit the present invention. Furthermore, the terms "first," "second," and "third" are intended only for explanatory purposes and cannot be understood as indicating or implying relative importance.

[0025] In the description of this application, it should be understood that unless otherwise specified and limited, the terms "attached," "coupled," and "connected" may be broadly understood to mean, for example, a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, or internal communication between two elements. Those skilled in the art will be able to understand the specific meanings of the above terms in this application depending on the specific circumstances.

[0026] Furthermore, the technical features according to different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] 1 shows a specific embodiment of an integrated variable speed phase modulator system, which includes a step-up transformer 5, a variable frequency AC converter, and a variable speed phase modulator 1. The step-up transformer 5 is suitable for line connection with a power system. Specifically, the variable speed phase modulator 1 is a generator.

[0028] As shown in Fig. 1, the step-up transformer 5 has a low-voltage side and a high-voltage side, the variable-speed phase modulator 1 has a current input terminal, an AC rotor, a stator, and a current output terminal, and the variable-frequency AC converter 3 is connected to the low-voltage side and the current input terminal by lines, and the high-voltage side is connected to the current output terminal by lines. As shown in Fig. 1, the AC rotor is a three-phase rotor having U, V, and W phases, and flywheels 2 are provided on both coaxial ends of the AC rotor. A capacitor 5 is further provided which is connected to the step-up transformer 5 by lines.

[0029] In the primary frequency modulation process, when the power system frequency is too low to meet the primary frequency modulation requirement, the variable frequency AC converter 3 receives power from the step-up transformer 5, adjusts the power to a variable frequency, low-frequency AC power, and outputs it to the current input terminal. This causes the AC rotor of the variable speed phase modulator 1 to drive the flywheel 2, reducing its rotational speed and increasing the active power output to the power system. The rotor speed of the variable speed phase modulator 1 then decreases, and the actual frequency at the current output terminal of the variable speed phase modulator 1 and the frequency of the power system both reach 50 Hz. This increases the frequency of the AC power output from the variable frequency AC converter 3 to the AC rotor, and the frequency of the AC power induced by the stator of the variable speed phase modulator 1 also reaches 50 Hz. If the output active power does not meet the primary frequency modulation requirement, the active power is output to the low-voltage side of the step-up transformer 5 via capacitor 4 to meet the primary frequency modulation requirement of the variable speed phase modulator 1.

[0030] To further regulate the system, a reactive power compensator is further provided, the reactive power compensator being connected by line to the power system and to the phase modulator 1, respectively, to regulate the reactive power output in combination with the phase modulator in response to changes in the power supply of the power system.

[0031] When the power system frequency is too high to meet the primary frequency modulation requirement, the variable frequency AC converter 3 receives power from the step-up transformer 5, adjusts it to a variable frequency low-frequency AC power supply, and outputs it to the current input terminal. This causes the AC rotor of the variable speed phase modulator 1 to drive the flywheel 2, increasing its rotational speed and absorbing active power from the power system. This increases the rotor's rotational speed and mechanical frequency, so that the actual frequency at the current output terminal of the variable speed phase modulator 1 and the frequency of the power system both reach 50 Hz. This reduces the frequency of the AC power output from the variable frequency AC converter 3 to the AC rotor, and the frequency of the AC power induced by the stator of the variable speed phase modulator 1 also reaches 50 Hz. If the output active power cannot meet the primary frequency modulation requirement, the capacitor 4 absorbs the active power from the low-voltage side of the step-up transformer 5 to meet the variable speed phase modulator 1's requirement for primary frequency modulation.

[0032] In the primary frequency modulation process, when the voltage of the power system rises, the variable frequency AC converter 3 reduces the AC excitation current output to the variable speed phase modulator 1, causing the variable speed phase modulator 1 to absorb reactive power from the power system and reduce the voltage of the power system. When the voltage of the power system drops, the variable frequency AC converter 3 increases the AC excitation current output to the variable speed phase modulator 1, causing the variable speed phase modulator 1 to transmit reactive power to the power system and increase the voltage of the power system. When the reactive power provided by the variable speed phase modulator 1 is insufficient, the power system still has insufficient reactive power, but the reactive power compensator supplies corresponding reactive power to the power system to maintain the stability of the voltage of the entire system. When the power system is in steady state, it will compare it with the reactive power reference value, output a missing feedback signal after comparison, send the reactive power to the power system by the reactive power compensator and detect it again, if the system is still lower than the reference value, send the reactive power to the power system by the variable speed phase modulator 1, if an excessive feedback signal is output after comparison, absorb the reactive power by the reactive power compensator and detect it again, if the system is still higher than the reference value, absorb the reactive power of the power system by the variable speed phase modulator 1.

[0033] Obviously, the above examples are merely examples for the purpose of clarity and are not intended to limit the embodiments. Those skilled in the art can make other different modifications or changes based on the above description. It is not necessary or possible to cover all the embodiments here. Any obvious modifications or changes derived therefrom still fall within the scope of protection of the present invention. [Explanation of symbols]

[0034] 1 variable speed phase modulator, 2 flywheel, 3 variable frequency current converter, 4 capacitor, 5 step-up transformer.

Claims

1. 1. An integrated variable speed phase modulator system comprising: a step-up transformer (5) suitable for line connection to a power system; a variable frequency current converter (3) connected in line to said step-up transformer (5); a variable speed phase modulator (1) having a current input terminal, an AC rotor, and a current output terminal, the current input terminal being connected to a variable frequency current converter (3) by a line, the current output terminal being connected to a step-up transformer (5) by a line, and flywheels (2) being provided at both coaxial ends of the AC rotor, the variable frequency current converter (3) receiving power from the step-up transformer (5), adjusting the power to a variable frequency low frequency AC power supply and outputting it to the current input terminal, the AC rotor driving and rotating the flywheel (2) and adjusting the moment of inertia of the rotating AC rotor, so that the frequency of the power supply generated by the variable speed phase modulator (1) becomes the same as the frequency of the power system, and the power is input from the current output terminal to the power system via the step-up transformer (5); and a capacitor (4) connected in line to a step-up transformer (5).

2. 2. The integrated variable speed phase modulator system of claim 1, wherein the step-up transformer (5) has a low voltage side connected in line to a variable frequency current converter (3).

3. 3. The integrated variable speed phase modulator system according to claim 2, wherein the step-up transformer (5) further comprises a high voltage side connected to the current output terminal by a line.

4. 2. The integrated variable speed phase modulator system of claim 1, wherein the AC power supply has a frequency of 50 Hz.

5. 5. The integrated variable speed phase modulator system of claim 4, wherein the AC rotor has three phases: U, V, and W.

6. The integrated variable speed phase modulator system according to claim 5, characterized in that the variable speed phase modulator (1) further comprises a stator.

7. 7. The integrated variable speed phase modulator system of claim 6, further comprising a reactive power compensator.

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