CN116418014A

CN116418014A - Control method, system controller and medium of grid-connected power generation system

Info

Publication number: CN116418014A
Application number: CN202310666915.5A
Authority: CN
Inventors: 关东英; 鄢秋亮; 刘�东; 贺智威; 白宁; 杨晶
Original assignee: Candela Shenzhen New Energy Technology Co Ltd
Current assignee: Candela Shenzhen New Energy Technology Co Ltd
Priority date: 2023-06-07
Filing date: 2023-06-07
Publication date: 2023-07-11
Anticipated expiration: 2043-06-07
Also published as: CN116418014B

Abstract

The embodiment of the application discloses a control method, a control system and a storage medium suitable for a grid-connected power generation system, wherein the method is applied to the grid-connected power generation system and comprises the following steps: when the frequency deviation value is positive and larger than a preset positive dead zone frequency or the frequency deviation value is negative and smaller than a preset negative dead zone frequency, calculating a power compensation value for primary frequency modulation according to the frequency deviation value; selecting a power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system; and controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value. The method is suitable for primary frequency modulation in a reserved power generation power range, and is simultaneously suitable for primary frequency modulation in a combination range of reserved power generation power and power of a second power generation subsystem, so that the application range of primary frequency modulation is improved, and the efficiency of autonomously supporting the frequency stability of the alternating current power grid is also improved.

Description

Control method, system controller and medium of grid-connected power generation system

Technical Field

The present disclosure relates to the field of power grid regulation technologies, and in particular, to a control method, a system controller, and a medium for a grid-connected power generation system.

Background

The traditional power generation mode mainly comprises the steps that fossil fuel is combusted in a thermal power plant to drive a gas turbine unit to generate power, and new energy power generation such as photovoltaic power, wind power and tide inevitably enters a rapid development stage and gradually replaces traditional fossil fuel power generation.

Along with the continuous increase of the installed quantity of new energy power generation, the installed quantity of traditional fossil fuel power generation is reduced, so that the primary frequency modulation capability of the traditional fossil fuel power generation to the power grid is weakened, and the stability of the power grid is reduced. At present, the inertia of the new energy power grid mainly comes from virtual inertia generated by an inverter device and a virtual inertia control algorithm, and the virtual inertia cannot be naturally coupled with an alternating current power grid to run, so that disturbance of the alternating current power grid cannot be responded, and frequency stability of the alternating current power grid cannot be autonomously supported.

Disclosure of Invention

In view of this, the present application provides a control method, a system and a storage medium suitable for a grid-connected power generation system, which are used for solving the technical problems that in the prior art, the inertia of a new energy power grid mainly comes from virtual inertia generated by an inverter device and a virtual inertia control algorithm, and the virtual inertia cannot achieve natural coupling operation with an ac power grid, so that the disturbance of the ac power grid cannot be responded, and the frequency stability of the ac power grid cannot be independently supported.

In a first aspect, the present application proposes a control method of a grid-connected power generation system, where the method is applied to the grid-connected power generation system, the grid-connected power generation system includes: the system comprises a first power generation subsystem, a second power generation subsystem, a grid-connected switch and a detection device; the first power generation subsystem comprises an energy storage flywheel array, a motor inverter and a synchronous motor-synchronous camera system which are sequentially connected, and the second power generation subsystem comprises an energy storage flywheel array and a grid-connected inverter which are sequentially connected; the synchronous motor-synchronous camera system comprises a synchronous motor and a synchronous camera which are sequentially connected, the motor inverter is respectively connected with the energy storage flywheel array and the synchronous motor, and the grid-connected inverter is connected with the energy storage flywheel array; when the synchronous motor is in a connection state with the synchronous camera, the synchronous motor can drive the synchronous camera to synchronously rotate for generating electricity; the synchronous phase regulator is connected with the grid-connected switch and can be connected with an alternating current power grid through the grid-connected switch, the grid-connected inverter is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, and the detection device is used for detecting the power grid instantaneous frequency of the alternating current power grid;

The method comprises the following steps:

acquiring a frequency deviation value between the instantaneous frequency of the power grid and a preset rated frequency of the power grid;

when the frequency deviation value is positive and larger than a preset positive dead zone frequency or the frequency deviation value is negative and smaller than a preset negative dead zone frequency, calculating a power compensation value for primary frequency modulation according to the frequency deviation value;

selecting a power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system;

and controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value.

In a second aspect, the present application proposes a control system of a grid-connected power generation system, the grid-connected power generation system comprising: the system comprises a system controller, a first power generation subsystem, a second power generation subsystem, a grid-connected switch and a detection device; the first power generation subsystem comprises an energy storage flywheel array, a motor inverter and a synchronous motor-synchronous camera system which are sequentially connected, and the second power generation subsystem comprises an energy storage flywheel array and a grid-connected inverter which are sequentially connected; the synchronous motor-synchronous camera system comprises a synchronous motor and a synchronous camera which are sequentially connected, the motor inverter is respectively connected with the energy storage flywheel array and the synchronous motor, and the grid-connected inverter is connected with the energy storage flywheel array; when the synchronous motor is in a connection state with the synchronous camera, the synchronous motor can drive the synchronous camera to synchronously rotate for generating electricity; the synchronous phase regulator is connected with the grid-connected switch and can be connected with an alternating current power grid through the grid-connected switch, the grid-connected inverter is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, and the detection device is used for detecting the power grid instantaneous frequency of the alternating current power grid; the system controller comprises a memory storing a computer program and a processor adapted to implement the steps of the control method of the grid-connected power generation system of any one of the first aspects when the computer program is executed.

In a third aspect, the present application proposes a computer readable storage medium storing a computer program, which when executed by a processor implements the steps of the control method of the grid-connected power generation system of any one of the first aspects.

In a fourth aspect, the present application proposes a system controller of a grid-connected power generation system, including a memory, and a processor, where the memory stores a computer program executable on the processor, and the processor implements the steps of the control method of the grid-connected power generation system according to any one of the first aspects when the processor executes the computer program.

Implementation of the embodiment of the application has the following beneficial effects:

(1) In the application, when the frequency deviation value is positive and greater than a preset positive dead zone frequency, or the frequency deviation value is negative and less than a preset negative dead zone frequency, calculating a power compensation value for primary frequency modulation according to the frequency deviation value, selecting a power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system, and controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value, so that the frequency of an alternating current power grid is quickly responded and adjusted, the primary frequency modulation participating in the alternating current power grid is realized, and further the frequency stability of the alternating current power grid is autonomously supported.

(2) In the application, the power generation subsystem which needs to be connected with the power grid is selected according to the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system in the first power generation subsystem, so that the application is suitable for primary frequency modulation in the reserved power generation power range, and meanwhile, the application is also suitable for primary frequency modulation in the combination range of the reserved power generation power and the power of the second power generation subsystem, the application range of primary frequency modulation is improved, and the efficiency of independently supporting the frequency stability of the alternating current power grid is also improved.

(3) In the method, inertia response to the alternating current power grid is achieved through the synchronous motor and the synchronous camera, enough mechanical inertia supporting capacity is provided for the alternating current power grid, impact caused by instantaneous load change at the power grid side is avoided, and stability of the power grid is improved.

(4) A large number of power electronic devices are used in the traditional new energy grid connection process, so that harmonic waves which harm a power grid are generated, particularly the harmonic wave content after high-proportion new energy grid connection is larger and larger, and the power grid is crashed when serious; meanwhile, the power electronic device in the grid-connected system can be directly damaged by the power grid fault, and the system can be destroyed and economic loss can be caused. According to the method, the synchronous motor drives the synchronous camera to synchronously rotate to generate power so as to realize secondary power generation grid connection, the influence of the harmonic waves of the power electronic device in the new energy station on the alternating current power grid can be isolated, the influence of the alternating current power grid fault on the internal power grid of the new energy station can be isolated, the stability of the power grid is improved, and the safety of the internal power grid of the new energy station is protected.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Wherein:

FIG. 1 is a schematic diagram of an application environment of a control method of a grid-connected power generation system in one embodiment;

FIG. 2 is a general flow chart of primary frequency modulation of a control method of a grid-connected power generation system in one embodiment;

FIG. 3 is a detailed flow chart of primary frequency modulation of a control method of a grid-connected power generation system in one embodiment;

FIG. 4 is a block diagram of a grid-tied power generation system in one embodiment;

fig. 5 is a block diagram of a system controller of the grid-connected power generation system in one embodiment.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

In order to better understand the control method, system controller and medium of the grid-connected power generation system disclosed in the present application, an application environment of the control method of the grid-connected power generation system is first described, specifically, the control method of the grid-connected power generation system is used for controlling the grid-connected power generation system, and the grid-connected power generation system includes: the first power generation subsystem, the second power generation subsystem, the grid-connected switch 010 and the detection device 009; the first power generation subsystem comprises an energy storage flywheel array 002, a motor inverter 003 and a synchronous motor-synchronous camera system 004 which are connected in sequence, and the second power generation subsystem comprises an energy storage flywheel array 002 and a grid-connected inverter 007 which are connected in sequence; the energy storage flywheel array 002 is used for being connected with the power generation unit 001 and taking power from the power generation unit 001, the synchronous motor-synchronous camera system 004 comprises a synchronous motor and a synchronous camera which are sequentially connected, the motor inverter 003 is respectively connected with the energy storage flywheel array 002 and the synchronous motor, and the grid-connected inverter 007 is connected with the energy storage flywheel array 002; when the synchronous motor is in a connection state with the synchronous camera, the synchronous motor can drive the synchronous camera to synchronously rotate for generating electricity; the synchronous rectifier is connected with the grid-connected switch 010 and can be connected with the alternating current power grid 006 through the grid-connected switch 010, the grid-connected inverter 007 is connected with the grid-connected switch 010 and can be connected with the alternating current power grid 006 through the grid-connected switch 010, and the detection device 009 is used for detecting the power grid instantaneous frequency of the alternating current power grid 006. Therefore, inertia response to the alternating current power grid is realized through the synchronous motor and the synchronous camera, enough mechanical inertia supporting capacity is provided for the alternating current power grid, impact caused by instantaneous load change at the power grid side is avoided, and the stability of the power grid is improved. A large number of power electronic devices are used in the traditional new energy grid connection process, so that harmonic waves which harm a power grid are generated, particularly the harmonic wave content after high-proportion new energy grid connection is larger and larger, and the power grid is crashed when serious; meanwhile, the power electronic device in the grid-connected system can be directly damaged by the power grid fault, and the system can be destroyed and economic loss can be caused. According to the method, the synchronous motor drives the synchronous camera to synchronously rotate to generate power so as to realize secondary power generation grid connection, the influence of the harmonic waves of the power electronic device in the new energy station on the alternating current power grid can be isolated, the influence of the alternating current power grid fault on the internal power grid of the new energy station can be isolated, the stability of the power grid is improved, and the safety of the internal power grid of the new energy station is protected.

The traditional energy storage of chemical battery that adopts, but the charge and discharge number of times of chemical battery energy storage is not high, and short-time power output is difficult to accomplish the biggest, and sensitive to ambient temperature easily takes place the fire accident, in order to solve this problem, this application adopts energy storage flywheel array 002 energy storage, charge and discharge number of times is many, can output high-power in a short time, insensitive to ambient temperature, and standby loss is low to safe environmental protection.

The power generation unit is a power station that generates electricity. Optionally, the power generation unit is a new energy power generation unit. For example, the power generation unit is a new energy station that generates power using new energy such as photovoltaic, wind power, and tide. The power generated by the power generation unit needs to be connected to an alternating current power grid. The grid-connected power generation system is used for connecting the power generated by the power generation unit to an alternating current power grid.

The detection device 8 includes: the first frequency detection sensor is configured to detect, in real time, a grid instantaneous frequency of the ac power grid, for example, one end of the grid-connected switch S2 connected to the ac power grid is detected in real time, so as to detect the grid instantaneous frequency of the ac power grid. The first frequency detection sensor is a sensor for detecting a grid instantaneous frequency of the grid.

Optionally, the number of the energy storage flywheel arrays 002 is one, and the energy storage flywheel arrays 002 are connected with the motor inverter 003 and the grid-connected inverter 007.

Optionally, the number of the energy storage flywheel arrays 002 is two, the first energy storage flywheel array 002 is connected with the motor inverter 003, and the second energy storage flywheel array 002 is connected with the grid-connected inverter 007.

Optionally, the number of the grid-connected switches 010 is one, a first end of the grid-connected switch 010 is connected with the grid-connected inverter 007 and the synchronous phase adjuster, and a second end of the grid-connected switch 010 is connected with the ac power grid 006.

Optionally, the number of the grid-connected switches 010 is two; a first end of a first grid-connected switch 010 is connected with the grid-connected inverter 007, and a second end of the first grid-connected switch 010 is connected with the alternating current power grid 006; the first end of the second grid-connected switch 010 is connected with the synchronous camera, and the second end of the second grid-connected switch 010 is connected with the alternating current power grid 006.

The energy storage flywheel array 002 includes: a plurality of energy storage flywheel units, the energy storage flywheel units include: and the bidirectional converter and the energy storage flywheel are sequentially connected. The energy storage flywheel array 002 is also provided with an array controller, and the array controller controls the charge and discharge of the single energy storage flywheel unit through an array control algorithm, and simultaneously controls the single energy storage flywheel unit to output electric energy to the motor inverter 003 or the grid-connected inverter 007.

Optionally, the synchronous motor and the synchronous camera are coaxially connected through a coupler.

It can be understood that the energy storage flywheel array 002 takes electricity from the dc bus of the power generation unit, and the electric energy is converted from dc to ac by the bidirectional converter and then enters the energy storage flywheel for charging.

The working principle of the first power generation subsystem is as follows: the electric energy of the energy storage flywheel is converted from alternating current to direct current through the bidirectional converter, then enters the motor inverter 003, the motor inverter 003 converts direct current into alternating current to drive the synchronous motor-synchronous camera system 004 to perform secondary power generation, and the electric energy generated by the secondary power generation is integrated into the alternating current power grid 006 through the grid-connected switch 010.

The working principle of the second power generation subsystem is as follows: the electric energy of the energy storage flywheel is converted from alternating current to direct current through a bidirectional converter and then enters a grid-connected inverter 007; grid-tied inverter 007 converts the electrical energy from dc to ac and then into the ac grid 006.

It can be understood that a system controller can be arranged in the grid-connected power generation system to load a program file for realizing the control method of the grid-connected power generation system, a switch control circuit can be arranged in the grid-connected power generation system to realize the method steps of the control method of the grid-connected power generation system, and a system can be arranged outside the grid-connected power generation system to load a program file for realizing the control method of the grid-connected power generation system.

The grid-connected power generation system is a power generation system and can be arranged in new energy stations such as photovoltaic, wind power and the like. The grid-connected power generation system can be used as a power generation side together with a traditional thermal power station or independently used as the power generation side to imitate the traditional thermal power station so as to supply power for a rear-end load. The grid-connected power generation system is a regulator of an alternating current power grid at the same time, for example, if the power generation power is not matched with the power consumption power of the alternating current power grid, the frequency of the alternating current power grid can rise or fall, and at the moment, the grid-connected power generation system can be controlled to have less output mechanical power and less power generation or more output mechanical power and more power generation so as to realize the regulation of the frequency of the alternating current power grid; of course, the synchronous generator of the grid-connected power generation system can also be used as a regulator of reactive power.

The above is only to express the environment used by the control method of the grid-connected power generation system, and the related grid-connected switch 010, the detection device 009, the energy storage flywheel array 002, the motor inverter 003, the synchronous motor-synchronous camera system 004, the grid-connected inverter 007, and the like are only schematically shown, and specific structures, dimensions, shapes, positions/installation manners, and the like can be adaptively adjusted according to actual requirements, which is not limited herein.

The application scenario used by the control method of the grid-connected power generation system is described above, and the control method, the system controller and the medium of the grid-connected power generation system are described in detail below.

As shown in fig. 2, in one embodiment, a control method of a grid-connected power generation system is provided. The method is applied to a grid-connected power generation system, and the grid-connected power generation system comprises: the system comprises a first power generation subsystem, a second power generation subsystem, a grid-connected switch and a detection device; the first power generation subsystem comprises an energy storage flywheel array, a motor inverter and a synchronous motor-synchronous camera system which are sequentially connected, and the second power generation subsystem comprises an energy storage flywheel array and a grid-connected inverter which are sequentially connected; the synchronous motor-synchronous camera system comprises a synchronous motor and a synchronous camera which are sequentially connected, the motor inverter is respectively connected with the energy storage flywheel array and the synchronous motor, and the grid-connected inverter is connected with the energy storage flywheel array; when the synchronous motor is in a connection state with the synchronous camera, the synchronous motor can drive the synchronous camera to synchronously rotate for generating electricity; the synchronous phase regulator is connected with the grid-connected switch and can be connected with an alternating current power grid through the grid-connected switch, the grid-connected inverter is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, and the detection device is used for detecting the power grid instantaneous frequency of the alternating current power grid;

The method comprises the following steps:

s1: acquiring a frequency deviation value between the instantaneous frequency of the power grid and a preset rated frequency of the power grid;

the power grid instantaneous frequency is the alternating current power supply frequency of the alternating current power grid detected in real time.

The preset rated frequency of the power grid is the rated alternating current power supply frequency of the alternating current power grid. Optionally, the preset rated frequency of the power grid is 50HZ.

Specifically, the power grid instantaneous frequency of the alternating current power grid sent by the detection device is obtained, the latest obtained power grid instantaneous frequency is subtracted by the preset power grid rated frequency, and the subtracted data are used as frequency deviation values.

S2: when the frequency deviation value is positive and larger than a preset positive dead zone frequency or the frequency deviation value is negative and smaller than a preset negative dead zone frequency, calculating a power compensation value for primary frequency modulation according to the frequency deviation value;

frequency modulation is divided into two phases: a phase of inertia response and a phase of primary frequency modulation. The phase of inertia response wins time for the phase of primary frequency modulation. The phase of the inertia response is the frequency modulation of the passive response. The primary frequency modulation stage is actively performed frequency modulation.

When the frequency deviation value is outside the dead zone frequency range, the primary frequency modulation stage is required to be entered, wherein the dead zone frequency range is a range from a preset negative dead zone frequency to a preset positive dead zone frequency. When the frequency deviation value is within the dead band frequency range, no primary frequency modulation stage is required.

Optionally, the preset forward dead band frequency is 0.05HZ. It will be appreciated that the predetermined forward dead band frequency may be other values, such as, but not limited to, a value between 0.025HZ and 0.055 HZ.

Optionally, the preset negative dead band frequency is-0.05 HZ. It will be appreciated that the predetermined negative dead band frequency may be other values, such as, but not limited to, values between-0.055 HZ and-0.025 HZ.

Specifically, when the frequency deviation value is positive and is greater than the preset forward dead zone frequency, it means that primary frequency modulation is needed, and because the frequency deviation value is positive, it indicates that the active power of the ac power grid is excessive, that is, the load of the ac power grid is insufficient, at this time, if the synchronous motor maintains the original mechanical power output, the rotation speed of the rotor system formed by the synchronous motor and the synchronous modulator will continue to rise, and in order to inhibit the frequency of the ac power grid from continuously increasing, the power output to the ac power grid needs to be reduced through primary frequency modulation; when the frequency deviation value is negative and smaller than the preset negative dead zone frequency, the primary frequency modulation is needed, and the active power shortage of the alternating current power grid is indicated because the frequency deviation value is negative, that is, the load of the alternating current power grid is excessive, at the moment, if the synchronous motor maintains the original mechanical power output, the rotating speed of a rotor system formed by the synchronous motor and the synchronous regulator can be further reduced, and in order to inhibit the frequency of the alternating current power grid from further reducing, the power output to the alternating current power grid needs to be increased through the primary frequency modulation. Therefore, when the frequency deviation value is positive and greater than a preset positive dead frequency, or when the frequency deviation value is negative and less than a preset negative dead frequency, a primary frequency modulation is required.

The calculation method for calculating the power compensation value for primary frequency modulation according to the frequency deviation value may be selected from the prior art, and will not be described herein.

S3: selecting a power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system;

the synchronous motor-synchronous rectifier system reserves generated power for coping with power fluctuations on the grid side of the ac grid when designed. The generated power reserved by the synchronous motor-synchronous camera system comprises the following components: a first power and a second power; the first power is a reserved value of rated power of the synchronous motor, and the second power is a reserved value of rated power of the synchronous motor.

Optionally, the first power is 10% of the rated power of the synchronous motor, and the second power is 10% of the rated power of the synchronous motor. It is understood that the first power and the second power may be other values, which are not limited herein.

Specifically, comparing the absolute value of the power compensation value with the power generation power reserved by the synchronous motor-synchronous camera system, and selecting a power generation subsystem needing grid connection from a first power generation subsystem and a second power generation subsystem according to the comparison result. That is, the selection range of the power generation subsystem includes the first power generation subsystem and the second power generation subsystem.

S4: and controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value.

Specifically, if the selected power generation subsystem is the first power generation subsystem, controlling the first power generation subsystem to perform primary frequency modulation according to the power compensation value; and if the power generation subsystem selected by the control is a first power generation subsystem and a second power generation subsystem, controlling the first power generation subsystem and the second power generation subsystem to perform primary frequency modulation according to the power compensation value.

The technical effects of this embodiment are: (1) In the application, when the frequency deviation value is positive and greater than a preset positive dead zone frequency, or the frequency deviation value is negative and less than a preset negative dead zone frequency, calculating a power compensation value for primary frequency modulation according to the frequency deviation value, selecting a power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system, and controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value, so that the frequency of an alternating current power grid is quickly responded and adjusted, the primary frequency modulation participating in the alternating current power grid is realized, and further the frequency stability of the alternating current power grid is autonomously supported. (2) In the application, the power generation subsystem which needs to be connected with the power grid is selected according to the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system in the first power generation subsystem, so that the application is suitable for primary frequency modulation in the reserved power generation power range, and meanwhile, the application is also suitable for primary frequency modulation in the combination range of the reserved power generation power and the power of the second power generation subsystem, the application range of primary frequency modulation is improved, and the efficiency of independently supporting the frequency stability of the alternating current power grid is also improved. (3) In the method, inertia response to the alternating current power grid is achieved through the synchronous motor and the synchronous camera, enough mechanical inertia supporting capacity is provided for the alternating current power grid, impact caused by instantaneous load change at the power grid side is avoided, and stability of the power grid is improved. (4) A large number of power electronic devices are used in the traditional new energy grid connection process, so that harmonic waves which harm a power grid are generated, particularly the harmonic wave content after high-proportion new energy grid connection is larger and larger, and the power grid is crashed when serious; meanwhile, the power electronic device in the grid-connected system can be directly damaged by the power grid fault, and the system can be destroyed and economic loss can be caused. According to the method, the synchronous motor drives the synchronous camera to synchronously rotate to generate power so as to realize secondary power generation grid connection, the influence of the harmonic waves of the power electronic device in the new energy station on the alternating current power grid can be isolated, the influence of the alternating current power grid fault on the internal power grid of the new energy station can be isolated, the stability of the power grid is improved, and the safety of the internal power grid of the new energy station is protected.

In one embodiment, the step of selecting the power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation reserved by the synchronous motor-synchronous camera system includes:

s31: if the absolute value of the power compensation value is larger than the reserved power generation power, the first power generation subsystem and the second power generation subsystem are selected as power generation subsystems for grid connection;

specifically, if the absolute value of the power compensation value is greater than the reserved generated power, that is, the absolute value of the power compensation value is greater than the generated power reserved in design of the synchronous motor-synchronous modulation system, this means that the requirement of primary frequency modulation cannot be met by using the first power generation subsystem alone, and the second power generation subsystem needs to be started to supplement the primary frequency modulation, so that the first power generation subsystem and the second power generation subsystem are selected as power generation subsystems for grid connection.

S32: and if the absolute value of the power compensation value is smaller than or equal to the reserved power generation power, selecting the first power generation subsystem as a power generation subsystem for grid connection.

Specifically, if the absolute value of the power compensation value is smaller than or equal to the reserved generated power, that is, the absolute value of the power compensation value is smaller than or equal to the generated power reserved in design of the synchronous motor-synchronous camera system, this means that the requirement of primary frequency modulation can be met by using the first power generation subsystem alone, and therefore the first power generation subsystem is selected as the power generation subsystem for grid connection.

In this embodiment, when the absolute value of the power compensation value is smaller than or equal to the power generated by the synchronous motor-synchronous camera system reserved in design, the first power generation subsystem is selected as the power generation subsystem for grid connection, and at this time, primary frequency modulation is implemented by using the first power generation subsystem alone, and when the absolute value of the power compensation value is larger than the power generated by the synchronous motor-synchronous camera system reserved in design, the first power generation subsystem and the second power generation subsystem are selected as the power generation subsystem for grid connection, and on the basis of taking the first power generation subsystem as the primary frequency modulation main system, the method is suitable for primary frequency modulation in the combination range of the reserved power generated by the first power generation subsystem and the power generated by the second power generation subsystem, so that the application range for primary frequency modulation is improved, and the efficiency of autonomously supporting the frequency stability of the ac power grid is also improved.

In one embodiment, the first power generation subsystem further comprises: the input end of the first parallel network transformer is connected with the synchronous regulator, and the output end of the first parallel network transformer is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch; and/or the number of the groups of groups,

the second power generation subsystem further includes: the input end of the second grid-connected transformer is connected with the grid-connected inverter, and the output end of the second grid-connected transformer is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch.

And the first parallel network transformer is used for transforming the electric energy input into the first parallel network transformer and then merging the electric energy into the alternating current power grid. And the second grid-connected transformer is used for transforming the electric energy input into the second grid-connected transformer and then merging the electric energy into the alternating current power grid. The first parallel-network transformer and the second parallel-network transformer are both grid-connected transformers.

In an alternative implementation of this embodiment, the first power generation subsystem further includes: the input end of the first parallel network transformer is connected with the synchronous regulator, the output end of the first parallel network transformer is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, and the second power generation subsystem further comprises: the input end of the second grid-connected transformer is connected with the grid-connected inverter, and the output end of the second grid-connected transformer is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch.

In an alternative implementation of this embodiment, the first power generation subsystem further includes: the input end of the first parallel network transformer is connected with the synchronous regulator, and the output end of the first parallel network transformer is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch.

In an alternative implementation of the present embodiment, the second power generation subsystem further includes: the input end of the second grid-connected transformer is connected with the grid-connected inverter, and the output end of the second grid-connected transformer is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch.

It is understood that in this embodiment, the synchronous rectifier is not directly connected to the grid-connected switch, and the grid-connected inverter is not directly connected to the grid-connected switch.

According to the embodiment, the first grid-connected transformer is arranged for the first power generation subsystem and/or the second grid-connected transformer is arranged for the second power generation subsystem, so that the voltage of electric energy is adjusted before grid connection, the grid-connected stability of the grid-connected power generation system is improved, and the adaptability of the grid-connected power generation system is improved.

In one embodiment, the first power generation subsystem further comprises: the inertia flywheel is coaxially connected with the synchronous camera;

after the step of obtaining the frequency deviation value between the instantaneous frequency of the power grid and the preset rated frequency of the power grid, the method further comprises the following steps:

s5: and when the frequency deviation value is not equal to 0, controlling the synchronous motor, the synchronous regulator and the inertia flywheel to realize inertia response to the alternating current power grid.

Specifically, when the frequency deviation value is not equal to 0, it means that the instantaneous frequency of the ac power grid does not meet the preset requirement (preset rated frequency of the power grid), frequency modulation is needed for the ac power grid, and at the moment, the inertia response of the ac power grid is realized through the synchronous motor, the synchronous tuner and the inertia flywheel, so that the frequency change rate is delayed, the rapid frequency drop is prevented, and when primary frequency modulation is needed, the inertia response of the ac power grid is realized through the synchronous motor, the synchronous tuner and the inertia flywheel, so that the time is gained for primary frequency modulation. The load shedding instruction is prevented from being triggered by overlarge frequency change of the alternating current power grid, so that power grid accidents are prevented from being caused.

The rotor of the synchronous motor, the rotor of the synchronous camera and the inertia flywheel form a rotor system, and inertia support is provided through the rotational inertia of the rotor system so as to realize inertia response to the alternating current power grid. The inertial support is a short-time impact type power support.

Optionally, the inertia flywheel and the synchronous camera are coaxially connected through a coupler.

Because the moment of inertia of the rotor system is mechanical inertia, the moment of inertia of a power generation system (for example, a system formed by the synchronous motor and the synchronous camera) is constant, and the available inertia support is limited, in order to solve the problem, in this embodiment, not only the moment of inertia support provided by the generator rotor and the turbine rotor during conventional fossil fuel power generation is replaced by the rotor of the synchronous motor and the rotor of the synchronous camera, but also the inertia is increased by the inertia flywheel, the inertia time constant is prolonged by increasing the inertia, and the inertia support power is increased by extending the inertia time constant.

As shown in fig. 3, in one embodiment, the step of controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value includes:

S41: when the power compensation value is larger than 0 and the selected power generation subsystem is the first power generation subsystem, controlling the energy storage flywheel array to reduce the power output by the first power generation subsystem according to the power compensation value;

specifically, when the power compensation value is greater than 0, it means that the frequency deviation value is positive and greater than a preset forward dead zone frequency, and primary frequency modulation is needed, and because the frequency deviation value is positive, it indicates that active power of the ac power grid is excessive, that is, load of the ac power grid is insufficient, at this time, if the synchronous motor maintains original mechanical power output, the rotation speed of a rotor system formed by the synchronous motor and the synchronous tuner will continue to rise, and in order to inhibit the frequency of the ac power grid from continuously increasing, power output to the ac power grid needs to be reduced through primary frequency modulation; when the selected power generation subsystem is the first power generation subsystem, the first power generation subsystem can be independently used to meet the requirement of primary frequency modulation; thus, when the power compensation value is greater than 0 and the selected power generation subsystem is the first power generation subsystem, the energy storage flywheel array is controlled to reduce the power output by the first power generation subsystem according to the power compensation value.

S42: when the power compensation value is larger than 0 and the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, controlling the energy storage flywheel array to reduce the power output by the first power generation subsystem according to the power compensation value, and controlling the energy storage flywheel array to absorb active power from the alternating current power grid by the second power generation subsystem according to the power compensation value;

specifically, when the power compensation value is greater than 0, it means that the frequency deviation value is positive and greater than a preset forward dead zone frequency, and primary frequency modulation is needed, and because the frequency deviation value is positive, it indicates that active power of the ac power grid is excessive, that is, load of the ac power grid is insufficient, at this time, if the synchronous motor maintains original mechanical power output, the rotation speed of a rotor system formed by the synchronous motor and the synchronous tuner will continue to rise, and in order to inhibit the frequency of the ac power grid from continuously increasing, power output to the ac power grid needs to be reduced through primary frequency modulation; when the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, the first power generation subsystem and the second power generation subsystem are used simultaneously to meet the requirement of primary frequency modulation; thus, according to the power compensation value, the energy storage flywheel array is controlled to reduce the power output by the first power generation subsystem to mainly reduce the active power of the alternating current power grid, and according to the power compensation value, the energy storage flywheel array is controlled to extract the active power from the alternating current power grid by the second power generation subsystem to realize auxiliary reduction of the active power of the alternating current power grid.

Optionally, controlling the energy storage flywheel array to reduce the power output by the first power generation subsystem according to the reserved power generation power; and controlling the energy storage flywheel array to absorb active power from the alternating current power grid through the second power generation subsystem according to a difference value obtained by subtracting the reserved power generation power from the absolute value of the power compensation value. Thereby minimizing the active power drawn by the second power generation subsystem from the ac power grid.

Optionally, controlling the energy storage flywheel array to reduce the power output by the first power generation subsystem according to the value smaller than the reserved power generation power; and subtracting the reserved generated power from the absolute value of the power compensation value to obtain a difference value, and controlling the energy storage flywheel array to absorb active power from the alternating current power grid through the second power generation subsystem according to a value larger than the difference value. Thereby shortening the time required for primary frequency modulation.

S43: when the power compensation value is smaller than 0 and the selected power generation subsystem is the first power generation subsystem, controlling the energy storage flywheel array to increase the power output by the first power generation subsystem according to the power compensation value;

Specifically, when the power compensation value is smaller than 0, it means that the frequency deviation value is negative and smaller than the preset negative dead zone frequency, and primary frequency modulation is needed, and because the frequency deviation value is negative, the active power shortage of the ac power grid is indicated, that is, the load of the ac power grid is excessive, and if the synchronous motor maintains the original mechanical power output, the rotation speed of a rotor system formed by the synchronous motor and the synchronous regulator is further reduced, and in order to inhibit the frequency of the ac power grid from further dropping, the power output to the ac power grid needs to be increased through primary frequency modulation; when the selected power generation subsystem is the first power generation subsystem, the first power generation subsystem can be independently used to meet the requirement of primary frequency modulation; thus, when the power compensation value is less than 0 and the selected power generation subsystem is the first power generation subsystem, the energy storage flywheel array is controlled to increase the power output by the first power generation subsystem according to the power compensation value.

S44: when the power compensation value is smaller than 0 and the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, the energy storage flywheel array is controlled to increase the power output by the first power generation subsystem according to the power compensation value, and the energy storage flywheel array is controlled to output the power by the second power generation subsystem according to the power compensation value.

Specifically, when the power compensation value is smaller than 0, it means that the frequency deviation value is negative and smaller than the preset negative dead zone frequency, and primary frequency modulation is needed, and because the frequency deviation value is negative, the active power shortage of the ac power grid is indicated, that is, the load of the ac power grid is excessive, and if the synchronous motor maintains the original mechanical power output, the rotation speed of a rotor system formed by the synchronous motor and the synchronous regulator is further reduced, and in order to inhibit the frequency of the ac power grid from further dropping, the power output to the ac power grid needs to be increased through primary frequency modulation; when the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, the first power generation subsystem and the second power generation subsystem are used simultaneously to meet the requirement of primary frequency modulation; therefore, when the power compensation value is smaller than 0 and the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, the energy storage flywheel array is controlled to increase the power output by the first power generation subsystem according to the power compensation value, and the energy storage flywheel array is controlled to output the power by the second power generation subsystem according to the power compensation value so as to realize auxiliary increase of the power output by the alternating current power grid.

Optionally, according to the reserved generated power, controlling the energy storage flywheel array to increase the power output by the first power generation subsystem; and controlling the energy storage flywheel array to output power through the second power generation subsystem according to the difference value obtained by subtracting the reserved power generation power from the absolute value of the power compensation value. Thereby realizing the reduction of the power output by the second power generation subsystem to the alternating current power grid as much as possible.

Optionally, controlling the energy storage flywheel array to increase the power output by the first power generation subsystem according to the value smaller than the reserved power generation power; and subtracting the reserved generated power from the absolute value of the power compensation value to obtain a difference value, and controlling the energy storage flywheel array to output power through the second power generation subsystem according to the value larger than the difference value. Thereby shortening the time required for primary frequency modulation.

According to the embodiment, when the power compensation value is greater than 0 and the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, the energy storage flywheel array is controlled to reduce the power output by the first power generation subsystem according to the power compensation value, and the energy storage flywheel array is controlled to absorb active power from the alternating current power grid through the second power generation subsystem according to the power compensation value, when the power compensation value is smaller than 0 and the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, the energy storage flywheel array is controlled to increase the power output by the first power generation subsystem according to the power compensation value, and the energy storage flywheel array is controlled to output power by the second power generation subsystem according to the power compensation value, so that the energy storage flywheel array is suitable for primary frequency modulation within the combination range of reserved power generation power and power of the second power generation subsystem on the basis of taking the first power generation subsystem as a primary frequency modulation main system, the primary frequency modulation application is improved, the self-adaptive frequency stability of the alternating current power grid is also improved.

In one embodiment, the energy storage flywheel array comprises a plurality of energy storage flywheel units, the energy storage flywheel units enter a pure charge mode when the remaining energy data of the energy storage flywheel units is smaller than a preset first threshold value, the energy storage flywheel units enter a charge-discharge mode when the remaining energy data of the energy storage flywheel units is larger than or equal to the preset first threshold value and smaller than or equal to a preset second threshold value, and the energy storage flywheel units enter the pure discharge mode when the remaining energy data of the energy storage flywheel units is larger than the preset second threshold value;

the remaining energy data may be a percentage or a specific electrical value.

Optionally, the preset first threshold is set to 30% and the preset second threshold is set to 98%.

Optionally, the preset first threshold is set to 30% of the rated stored energy of the energy storage flywheel unit, and the preset second threshold is set to 98% of the rated stored energy of the energy storage flywheel unit.

It is understood that the preset first threshold value and the preset second threshold value may also be set to other values, which are not limited herein.

The pure charge mode is a charge-only and discharge-free operation mode. The pure charging mode is executed, and is mainly used for maintaining the energy storage flywheel unit to always work in a constant power interval, so that the power limit of the energy storage flywheel array can be conveniently counted.

The charge and discharge mode is a chargeable and dischargeable operation mode. Through the charge and discharge mode, the charge and discharge power limit of the energy storage flywheel array can be conveniently adjusted according to the requirements of an alternating current power grid.

The pure discharge mode is an operation mode in which only discharge is performed without charge. Through the pure discharge mode, the energy storage flywheel unit is mainly protected, the energy storage flywheel unit is prevented from being overcharged, and the ageing risk of parts of the body of the energy storage flywheel unit is reduced.

It can be appreciated that the grid-connected power is increased by providing different grid-connected working paths (i.e., the first power generation subsystem and the second power generation subsystem) for each working mode of the energy storage flywheel array.

When the power compensation value is greater than 0, the method further comprises:

s451: controlling a first number of the energy storage flywheel units of the energy storage flywheel array in the charge-discharge mode and each of the energy storage flywheel units in the pure-discharge mode to reduce power output according to the power compensation value; and/or the number of the groups of groups,

s452: controlling each energy storage flywheel unit of the energy storage flywheel array in the pure charging mode and a second number of the energy storage flywheel units in the charging and discharging mode to absorb active power from the alternating current power grid according to the power compensation value;

Wherein the sum of the first number and the second number is equal to the number of the energy storage flywheel units in the charge-discharge mode, the first number is not less than 0, and the second number is not less than 0.

Specifically, when the power compensation value is greater than 0, the energy storage flywheel array mainly works as an energy storage flywheel unit in a pure charge mode and a charge-discharge mode.

In an alternative implementation of the present embodiment, controlling a first number of the energy storage flywheel units of the energy storage flywheel array in the charge-discharge mode and each of the energy storage flywheel units in the pure discharge mode to reduce a power output according to the power compensation value; and controlling each energy storage flywheel unit of the energy storage flywheel array in the pure charging mode and a second number of the energy storage flywheel units in the charging and discharging mode to draw active power from the alternating current power grid according to the power compensation value.

In an alternative implementation of the present embodiment, controlling the first number of the energy storage flywheel units of the energy storage flywheel array in the charge-discharge mode and the respective energy storage flywheel units in the pure discharge mode reduces the power output according to the power compensation value.

In an alternative implementation of the present embodiment, each of the energy storage flywheel units of the energy storage flywheel array in the pure charge mode and the second number of the energy storage flywheel units in the charge-discharge mode are controlled to draw active power from the ac grid according to the power compensation value.

By absorbing active power and/or reducing power output, the embodiment reduces active power output to the alternating current power grid under the condition that the work of the grid-connected power generation system is maintained, so that the frequency of the grid-connected power generation system and the frequency of the grid-connected point of the alternating current power grid can be quickly restored to be within the dead zone frequency range.

In one embodiment, when the power compensation value is less than 0, the method further comprises:

s461: and controlling a third number of the energy storage flywheel units in the charge and discharge mode and each of the energy storage flywheel units in the pure discharge mode of the energy storage flywheel array to increase power output according to the power compensation value, wherein the third number is not less than 0, and the third number is less than or equal to the number of the energy storage flywheel units in the charge and discharge mode.

According to the embodiment, by increasing the power output, the active power output to the alternating current power grid is increased, the active power shortage in the alternating current power grid is compensated, the frequency of grid-connected power generation and grid-connected points of the alternating current power grid can be quickly restored to be within the frequency range of a dead zone, and the power grid accident caused by further dropping of the frequency of the alternating current power grid is avoided.

s462: controlling a fourth number of the energy storage flywheel units of the energy storage flywheel array in the charge-discharge mode and each of the energy storage flywheel units in the pure charge mode to draw electricity from the power generation unit;

wherein the sum of the third number and the fourth number is equal to the number of the energy storage flywheel units in the charge-discharge mode, the third number is not less than 0, and the fourth number is not less than 0.

Specifically, when the power compensation value is smaller than 0, the energy storage flywheel array mainly works as an energy storage flywheel unit in a charge-discharge mode and a pure discharge mode.

According to the embodiment, by taking power from the power generation unit and increasing power output, active power output to the alternating current power grid is increased, the lacking active power in the alternating current power grid is compensated, the frequency of grid-connected power generation and grid-connected points of the alternating current power grid can be quickly restored to the frequency range of dead areas, power grid accidents caused by further falling of the frequency of the alternating current power grid are avoided, and the power is taken from the power generation unit, so that the risk that the operation of the whole grid-connected power generation system can not be maintained due to the falling of the energy storage flywheel array is avoided.

In one embodiment, the proportion of the energy storage flywheel units in the pure charge mode in the energy storage flywheel array is 25%, the proportion of the energy storage flywheel units in the charge-discharge mode in the energy storage flywheel array is 50%, and the proportion of the energy storage flywheel units in the pure discharge mode in the energy storage flywheel array is 25%.

That is, in the present embodiment, the duty ratios of the energy storage flywheel units in the pure charge mode, the charge-discharge mode, and the pure discharge mode in the energy storage flywheel array are: 1:2:1. It will be appreciated that in another embodiment of the present application, the duty cycle may be other values, and is not limited herein.

In this embodiment, the duty ratios of the energy storage flywheel units in the pure charge mode, the charge and discharge mode, and the pure discharge mode in the energy storage flywheel array are as follows: when the quantity of the energy storage flywheel units in the pure charging mode and the pure discharging mode is insufficient, the energy storage flywheel units can be divided from the charging and discharging modes, and the working stability of the grid-connected power generation system is improved.

In one embodiment, the power generation unit is a unit for generating power from new energy sources;

The synchronous phase-change device is connected with the alternating current power grid through the same grid-connected switch, or the synchronous phase-change device is connected with a first grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, and the grid-connected inverter is connected with a second grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch.

When the synchronous phase-change modulator and the grid-connected inverter are connected with the alternating current power grid through the same grid-connected switch, the control operation of the grid-connected switch enables the synchronous phase-change modulator and the grid-connected inverter to realize synchronous grid connection; when the synchronous phase regulator is connected with a first grid-connected switch and can be connected with an alternating current power grid through the grid-connected switch, and the grid-connected inverter is connected with a second grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, independent control of the first power generation subsystem and the second power generation subsystem is facilitated through the two grid-connected switches.

In one embodiment, the detecting means is further for detecting a grid transient voltage of the ac grid;

the method further comprises the steps of:

acquiring voltage deviation between the instantaneous voltage of the power grid and the rated voltage of the power grid of the alternating current power grid;

Judging whether the voltage deviation is out of a preset deviation range or not;

if the power grid is positioned, acquiring the instantaneous reactive power of the power grid of the alternating current power grid;

if the instantaneous reactive power of the power grid is larger than the rated reactive power of the power grid of the alternating current power grid, reducing the exciting current of the synchronous regulator rotor;

if the instantaneous reactive power of the power grid is smaller than the rated reactive power of the power grid of the alternating current power grid, increasing the exciting current of the synchronous regulator rotor;

and controlling the synchronous regulator to enter a generator mode until the voltage deviation is within the preset deviation range so as to realize normal power generation.

The power grid instantaneous voltage is the voltage of the alternating current power grid detected in real time.

The grid rated voltage of the ac grid is the rated voltage of the ac grid. Optionally, the rated voltage of the alternating current power grid is 220V.

Specifically, the power grid instantaneous voltage of the alternating current power grid sent by the detection device is obtained, the latest obtained power grid instantaneous voltage is subtracted by the power grid rated voltage of the alternating current power grid, and the subtracted data is used as a first voltage deviation value.

If not, i.e. if the voltage deviation is within a predetermined deviation range, this means that the voltage fluctuation range (i.e. the predetermined first deviation value range) is met, and reactive power regulation is not required.

If the voltage deviation is located, that is, the voltage deviation is located outside the preset deviation range, it means that the voltage fluctuation range (that is, the preset first deviation value range) is not met, and reactive power adjustment is needed, so that the power grid instantaneous reactive power of the ac power grid sent by the detection device can be obtained, and the power grid instantaneous reactive power of the ac power grid sent by the third party application can also be obtained.

Specifically, if the instantaneous reactive power of the power grid is greater than the rated reactive power of the ac power grid, this means that the reactive power of the ac power grid is excessive, the voltage will rise to increase the load loss of the user and overload operation, and even cause an accident of the power grid, at this time, the synchronous phase-change machine enters a phase-change machine mode from a generator mode, the exciting current of the rotor of the synchronous phase-change machine is reduced, so that the rotor of the synchronous phase-change machine is underexcited, and the induced electromotive force of the stator of the synchronous phase-change machine will drop, so as to be lower than the voltage of the ac power grid. Because a voltage difference occurs between the voltage of the synchronous regulator and the voltage of the alternating current power grid, the voltage difference can lead the stator winding of the synchronous regulator to generate an inductive reactive current which leads the induced electromotive force by 90 degrees but lags behind the voltage difference by 90 degrees, so that the current flows from the alternating current power grid to the synchronous regulator, and the synchronous regulator is equivalent to an inductive reactive load, namely, the synchronous regulator absorbs the inductive reactive power from the alternating current power grid to reduce the voltage of the alternating current power grid, and the voltage of the alternating current power grid reenters a voltage fluctuation range, thereby regulating the development of the alternating current power grid to a normal running direction.

Specifically, if the instantaneous reactive power of the power grid is smaller than the rated reactive power of the ac power grid, which means that the reactive power of the ac power grid is insufficient, the voltage will drop to cause excessive load current of the user and unable to work normally, and even large-area off-grid accidents will be caused when serious, at this time, the synchronous phase-modulating machine enters a phase-modulating machine mode from a generator mode, the exciting current of the rotor of the synchronous phase-modulating machine is increased to overexcitation the rotor of the synchronous phase-modulating machine, and the induced electromotive force of the stator of the synchronous phase-modulating machine will rise to be higher than the voltage of the ac power grid. Because a voltage difference occurs between the voltage of the synchronous regulator and the voltage of the alternating current power grid, the voltage difference can enable an inductive reactive current to be generated in a stator winding of the synchronous regulator, the inductive reactive current lags behind an induced electromotive force by 90 degrees and lags behind the voltage difference by 90 degrees, so that current flows from the synchronous regulator to the alternating current power grid, the synchronous regulator is equivalent to an inductive reactive power supply, namely, the synchronous regulator provides the inductive reactive power to the alternating current power grid to improve the voltage of the alternating current power grid, and the voltage of the alternating current power grid reenters a voltage fluctuation conforming range, thereby regulating the development of the alternating current power grid to a normal running direction.

Until the voltage deviation is within the preset deviation range, the alternating current power grid is enabled to normally operate, so that the synchronous motor can drive the synchronous speed regulator to synchronously rotate for power generation, and the synchronous speed regulator enters a generator mode to realize normal power generation.

It will be appreciated that an additional set of excitation systems is provided to control the excitation current on the rotor coils of the synchronous machine, rather than the synchronous machine itself being able to reduce the excitation current on its rotor.

Compared with the reactive power compensation device of the power electronics type used by the new energy station, the reactive power compensation device cannot continuously adjust reactive power compensation and cannot cope with the reactive power compensation problem of high power capacity such as power grid section, the synchronous phase-change machine has the characteristics of large single-machine capacity and continuous reactive power adjustment, meanwhile, the working characteristics of the synchronous phase-change machine are utilized, the working mode of the synchronous phase-change machine is controlled by switching on and off the separable coupler, so that two requirements of active power compensation and reactive power compensation are completed on one device, and the use cost of the grid-connected power generation system is reduced.

As shown in fig. 4, in one embodiment, a control system of a grid-connected power generation system is proposed, the grid-connected power generation system including: a system controller (not shown), a first power generation subsystem, a second power generation subsystem, a grid-connected switch 010, and a detection device 009; the first power generation subsystem comprises an energy storage flywheel array 002, a motor inverter 003 and a synchronous motor-synchronous camera system 004 which are connected in sequence, and the second power generation subsystem comprises an energy storage flywheel array 002 and a grid-connected inverter 007 which are connected in sequence; the energy storage flywheel array 002 is used for being connected with the power generation unit 001 and taking power from the power generation unit 001, the synchronous motor-synchronous camera system 004 comprises a synchronous motor and a synchronous camera which are sequentially connected, the motor inverter 003 is respectively connected with the energy storage flywheel array 002 and the synchronous motor, and the grid-connected inverter 007 is connected with the energy storage flywheel array 002; when the synchronous motor is in a connection state with the synchronous camera, the synchronous motor can drive the synchronous camera to synchronously rotate for generating electricity; the synchronous rectifier is connected with the grid-connected switch 010 and can be connected with an alternating current power grid 006 through the grid-connected switch 010, the grid-connected inverter 007 is connected with the grid-connected switch 010 and can be connected with the alternating current power grid 006 through the grid-connected switch 010, and the detection device 009 is used for detecting the power grid instantaneous frequency of the alternating current power grid 006; the system controller comprises a memory storing a computer program and a processor adapted to implement the steps of the control method of the grid-connected power generation system of any one of the above, when the computer program is executed.

The first power generation subsystem further includes: the input end of the first parallel-network transformer 005 is connected with the synchronous regulator, and the output end of the first parallel-network transformer 005 is connected with the grid-connected switch 010 and can be connected with the alternating current grid 006 through the grid-connected switch 010; and/or the number of the groups of groups,

the second power generation subsystem further includes: the input end of the second grid-connected transformer 008 is connected with the grid-connected inverter 007, and the output end of the second grid-connected transformer 008 is connected with the grid-connected switch 010 and can be connected with the alternating current power grid through the grid-connected switch 010.

The first power generation subsystem further includes: and the inertia flywheel is coaxially connected with the synchronous camera.

The power generation unit 001 is a unit for generating power by new energy; the synchronous phase-change camera is connected with the ac power grid 006 through the same grid-connected switch 010 with the grid-connected inverter 007, or the synchronous phase-change camera is connected with a first grid-connected switch 010 and can be connected with the ac power grid through the grid-connected switch 010, and the grid-connected inverter 007 is connected with a second grid-connected switch 010 and can be connected with the ac power grid through the grid-connected switch 010.

The detecting device 009 is also used for detecting the voltage of the ac power grid 006, detecting the rotation speed of the rotor of the synchronous motor, and detecting the rotation speed of the rotor of the synchronous motor.

In one embodiment, a computer readable storage medium is provided, the computer readable storage medium storing a computer program, the computer program implementing the steps of the control method of the grid-connected power generation system according to any one of the above when being executed by a processor. The technical effects of this embodiment are: (1) In the application, when the frequency deviation value is positive and greater than a preset positive dead zone frequency, or the frequency deviation value is negative and less than a preset negative dead zone frequency, calculating a power compensation value for primary frequency modulation according to the frequency deviation value, selecting a power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system, and controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value, so that the frequency of an alternating current power grid is quickly responded and adjusted, the primary frequency modulation participating in the alternating current power grid is realized, and further the frequency stability of the alternating current power grid is autonomously supported. (2) In the application, the power generation subsystem which needs to be connected with the power grid is selected according to the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system in the first power generation subsystem, so that the application is suitable for primary frequency modulation in the reserved power generation power range, and meanwhile, the application is also suitable for primary frequency modulation in the combination range of the reserved power generation power and the power of the second power generation subsystem, the application range of primary frequency modulation is improved, and the efficiency of independently supporting the frequency stability of the alternating current power grid is also improved. (3) In the method, inertia response to the alternating current power grid is achieved through the synchronous motor and the synchronous camera, enough mechanical inertia supporting capacity is provided for the alternating current power grid, impact caused by instantaneous load change at the power grid side is avoided, and stability of the power grid is improved. (4) A large number of power electronic devices are used in the traditional new energy grid connection process, so that harmonic waves which harm a power grid are generated, particularly the harmonic wave content after high-proportion new energy grid connection is larger and larger, and the power grid is crashed when serious; meanwhile, the power electronic device in the grid-connected system can be directly damaged by the power grid fault, and the system can be destroyed and economic loss can be caused. According to the method, the synchronous motor drives the synchronous camera to synchronously rotate to generate power so as to realize secondary power generation grid connection, the influence of the harmonic waves of the power electronic device in the new energy station on the alternating current power grid can be isolated, the influence of the alternating current power grid fault on the internal power grid of the new energy station can be isolated, the stability of the power grid is improved, and the safety of the internal power grid of the new energy station is protected.

As shown in fig. 5, in one embodiment, a system controller of a grid-connected power generation system is provided, including a memory 012 and a processor 011, where the memory 012 stores a computer program that can be executed by the processor 011, and the processor 011 implements the steps of the control method of the grid-connected power generation system described in any one of the above. The technical effects of this embodiment are: (1) In the application, when the frequency deviation value is positive and greater than a preset positive dead zone frequency, or the frequency deviation value is negative and less than a preset negative dead zone frequency, calculating a power compensation value for primary frequency modulation according to the frequency deviation value, selecting a power generation subsystem for grid connection according to the absolute value of the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system, and controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value, so that the frequency of an alternating current power grid is quickly responded and adjusted, the primary frequency modulation participating in the alternating current power grid is realized, and further the frequency stability of the alternating current power grid is autonomously supported. (2) In the application, the power generation subsystem which needs to be connected with the power grid is selected according to the power compensation value and the power generation power reserved by the synchronous motor-synchronous camera system in the first power generation subsystem, so that the application is suitable for primary frequency modulation in the reserved power generation power range, and meanwhile, the application is also suitable for primary frequency modulation in the combination range of the reserved power generation power and the power of the second power generation subsystem, the application range of primary frequency modulation is improved, and the efficiency of independently supporting the frequency stability of the alternating current power grid is also improved. (3) In the method, inertia response to the alternating current power grid is achieved through the synchronous motor and the synchronous camera, enough mechanical inertia supporting capacity is provided for the alternating current power grid, impact caused by instantaneous load change at the power grid side is avoided, and stability of the power grid is improved. (4) A large number of power electronic devices are used in the traditional new energy grid connection process, so that harmonic waves which harm a power grid are generated, particularly the harmonic wave content after high-proportion new energy grid connection is larger and larger, and the power grid is crashed when serious; meanwhile, the power electronic device in the grid-connected system can be directly damaged by the power grid fault, and the system can be destroyed and economic loss can be caused. According to the method, the synchronous motor drives the synchronous camera to synchronously rotate to generate power so as to realize secondary power generation grid connection, the influence of the harmonic waves of the power electronic device in the new energy station on the alternating current power grid can be isolated, the influence of the alternating current power grid fault on the internal power grid of the new energy station can be isolated, the stability of the power grid is improved, and the safety of the internal power grid of the new energy station is protected.

Those skilled in the art will appreciate that all or part of the processes in the methods of the above embodiments may be implemented by a computer program for instructing relevant hardware, where the program may be stored in a non-volatile computer readable storage medium, and where the program, when executed, may include processes in the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.

The foregoing disclosure is only illustrative of the preferred embodiments of the present application and is not intended to limit the scope of the claims herein, as the equivalent of the claims herein shall be construed to fall within the scope of the claims herein.

Claims

1. A control method of a grid-connected power generation system, the method being applied to a grid-connected power generation system, the grid-connected power generation system comprising: the system comprises a first power generation subsystem, a second power generation subsystem, a grid-connected switch and a detection device; the first power generation subsystem comprises an energy storage flywheel array, a motor inverter and a synchronous motor-synchronous camera system which are sequentially connected, and the second power generation subsystem comprises an energy storage flywheel array and a grid-connected inverter which are sequentially connected; the synchronous motor-synchronous camera system comprises a synchronous motor and a synchronous camera which are sequentially connected, the motor inverter is respectively connected with the energy storage flywheel array and the synchronous motor, and the grid-connected inverter is connected with the energy storage flywheel array; when the synchronous motor is in a connection state with the synchronous camera, the synchronous motor can drive the synchronous camera to synchronously rotate for generating electricity; the synchronous phase regulator is connected with the grid-connected switch and can be connected with an alternating current power grid through the grid-connected switch, the grid-connected inverter is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, and the detection device is used for detecting the power grid instantaneous frequency of the alternating current power grid;

The method comprises the following steps:

2. The method for controlling a grid-connected power generation system according to claim 1, wherein the step of selecting the power generation subsystem to be grid-connected based on the absolute value of the power compensation value and the generated power reserved by the synchronous motor-synchronous camera system comprises:

if the absolute value of the power compensation value is larger than the reserved power generation power, the first power generation subsystem and the second power generation subsystem are selected as power generation subsystems for grid connection;

and if the absolute value of the power compensation value is smaller than or equal to the reserved power generation power, selecting the first power generation subsystem as a power generation subsystem for grid connection.

3. The control method of a grid-connected power generation system according to claim 1, wherein the first power generation subsystem further comprises: the input end of the first parallel network transformer is connected with the synchronous regulator, and the output end of the first parallel network transformer is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch; and/or the number of the groups of groups,

4. The control method of a grid-connected power generation system according to claim 1, wherein the first power generation subsystem further comprises: the inertia flywheel is coaxially connected with the synchronous camera;

and when the frequency deviation value is not equal to 0, controlling the synchronous motor, the synchronous regulator and the inertia flywheel to realize inertia response to the alternating current power grid.

5. The method for controlling a grid-connected power generation system according to claim 2, wherein the step of controlling the selected power generation subsystem to perform primary frequency modulation according to the power compensation value comprises:

when the power compensation value is larger than 0 and the selected power generation subsystem is the first power generation subsystem, controlling the energy storage flywheel array to reduce the power output by the first power generation subsystem according to the power compensation value;

when the power compensation value is larger than 0 and the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, controlling the energy storage flywheel array to reduce the power output by the first power generation subsystem according to the power compensation value, and controlling the energy storage flywheel array to absorb active power from the alternating current power grid by the second power generation subsystem according to the power compensation value;

when the power compensation value is smaller than 0 and the selected power generation subsystem is the first power generation subsystem, controlling the energy storage flywheel array to increase the power output by the first power generation subsystem according to the power compensation value;

when the power compensation value is smaller than 0 and the selected power generation subsystem is the first power generation subsystem and the second power generation subsystem, the energy storage flywheel array is controlled to increase the power output by the first power generation subsystem according to the power compensation value, and the energy storage flywheel array is controlled to output the power by the second power generation subsystem according to the power compensation value.

6. The control method of a grid-connected power generation system according to claim 5, wherein the energy storage flywheel array includes a plurality of energy storage flywheel units, the energy storage flywheel units enter a pure charge mode when remaining energy data of the energy storage flywheel units is less than a preset first threshold, the energy storage flywheel units enter a charge-discharge mode when remaining energy data of the energy storage flywheel units is greater than or equal to the preset first threshold and less than or equal to a preset second threshold, and the energy storage flywheel units enter a pure discharge mode when remaining energy data of the energy storage flywheel units is greater than the preset second threshold;

controlling a first number of the energy storage flywheel units of the energy storage flywheel array in the charge-discharge mode and each of the energy storage flywheel units in the pure-discharge mode to reduce power output according to the power compensation value; and/or the number of the groups of groups,

controlling each energy storage flywheel unit of the energy storage flywheel array in the pure charging mode and a second number of the energy storage flywheel units in the charging and discharging mode to absorb active power from the alternating current power grid according to the power compensation value;

7. The control method of a grid-connected power generation system according to claim 6, wherein when the power compensation value is less than 0, the method further comprises:

and controlling a third number of the energy storage flywheel units in the charge and discharge mode and each of the energy storage flywheel units in the pure discharge mode of the energy storage flywheel array to increase power output according to the power compensation value, wherein the third number is not less than 0, and the third number is less than or equal to the number of the energy storage flywheel units in the charge and discharge mode.

8. The control method of a grid-connected power generation system according to claim 7, wherein when the power compensation value is less than 0, the method further comprises:

controlling a fourth number of the energy storage flywheel units of the energy storage flywheel array in the charge-discharge mode and each of the energy storage flywheel units in the pure charge mode to draw electricity from the power generation unit;

9. The control method of a grid-connected power generation system according to claim 6, wherein a proportion of the energy storage flywheel units in the pure charge mode in the energy storage flywheel array is 25%, a proportion of the energy storage flywheel units in the charge-discharge mode in the energy storage flywheel array is 50%, and a proportion of the energy storage flywheel units in the pure discharge mode in the energy storage flywheel array is 25%.

10. The control method of a grid-connected power generation system according to claim 1, wherein the power generation unit is a unit for generating power from new energy;

11. A control system for a grid-connected power generation system, the grid-connected power generation system comprising: the system comprises a system controller, a first power generation subsystem, a second power generation subsystem, a grid-connected switch and a detection device; the first power generation subsystem comprises an energy storage flywheel array, a motor inverter and a synchronous motor-synchronous camera system which are sequentially connected, and the second power generation subsystem comprises an energy storage flywheel array and a grid-connected inverter which are sequentially connected; the synchronous motor-synchronous camera system comprises a synchronous motor and a synchronous camera which are sequentially connected, the motor inverter is respectively connected with the energy storage flywheel array and the synchronous motor, and the grid-connected inverter is connected with the energy storage flywheel array; when the synchronous motor is in a connection state with the synchronous camera, the synchronous motor can drive the synchronous camera to synchronously rotate for generating electricity; the synchronous phase regulator is connected with the grid-connected switch and can be connected with an alternating current power grid through the grid-connected switch, the grid-connected inverter is connected with the grid-connected switch and can be connected with the alternating current power grid through the grid-connected switch, and the detection device is used for detecting the power grid instantaneous frequency of the alternating current power grid; the system controller comprises a memory storing a computer program and a processor adapted to implement the steps of the control method of a grid-connected power generation system as claimed in any one of claims 1 to 10 when the computer program is executed.

12. A computer-readable storage medium storing a computer program, wherein the computer program when executed by a processor implements the steps of the control method of a grid-connected power generation system as claimed in any one of claims 1 to 10.

13. A system controller of a grid-connected power generation system, comprising a memory, a processor, the memory storing a computer program executable on the processor, characterized in that the processor, when executing the computer program, implements the steps of the control method of a grid-connected power generation system as claimed in any one of claims 1 to 10.