A method, storage medium, and device for direct-connection of green electricity to a single user via frequency conversion AC aggregation.

Abstract

This invention discloses a variable frequency AC aggregation method, storage medium, and equipment applicable to direct green electricity connection between wind and solar power clusters and a single user. The method selects the optimal nominal AC voltage value based on the power generation capacity of the wind and solar power cluster. It also divides the primary frequency regulation operating zone and the secondary frequency regulation target optimization range based on the matching status of power generation fluctuations and load. Furthermore, it sets the start-up range and adjustment mode of the automatic voltage regulator according to the frequency regulation operating mode. This method can adapt to the aggregation needs of wind and solar power clusters of different capacities, effectively improving the operational stability, security, and power quality of the aggregation system. It achieves efficient and controllable coupling between wind and solar power clusters and power users, and has practical, replicable, and scalable engineering application value.

Description

Technical Field

[0001] This invention belongs to the technical field of new energy power generation, specifically involving constant voltage variable frequency AC aggregation technology for wind and solar power generation. It mainly involves a variable frequency AC aggregation method, storage medium and equipment for direct green electricity connection to a single user, which is applicable to scenarios where wind power and photovoltaic intermittent power generation are aggregated via AC. Background Technology

[0002] Currently, the power supply of wind and solar power clusters mostly adopts the "grid connection first, power collection later" model, that is, the power is first connected to the public power grid, and then the power grid supplies power to various users. The mainstream power supply model for a single user also follows this logic, but it has obvious defects:

[0003] 1) The “grid connection first, power extraction later” model requires multiple steps such as grid dispatch, transformer step-up and step-down, and rectification and conversion, resulting in large power transmission losses and high grid connection costs, which significantly reduces economic efficiency.

[0004] 2) The “high voltage direct current collection” mode relies on a large number of converter equipment, resulting in high initial investment, complex safety protection, and inability to meet the flexible regulation requirements of intermittent wind and solar power output.

[0005] 3) Existing non-power frequency AC aggregation technologies, such as low frequency power transmission, are mostly designed for grid connection and are not optimized for the power supply characteristics of individual users. They lack safety control, voltage and frequency adaptation and power quality assurance mechanisms for off-grid direct supply.

[0006] In other words, for scenarios where wind and solar power clusters directly supply power to a single user, there is currently a lack of a suitable variable frequency AC voltage amplitude and frequency system. Existing technologies cannot achieve off-grid, low-loss, and highly stable direct supply of wind and solar green electricity to a single user, and cannot meet the single user's requirements for power supply stability and adaptability. Therefore, there is an urgent need for a dedicated power supply system and operation method that is adapted to a single user, does not require grid connection, and is based on constant voltage variable frequency AC aggregation. Summary of the Invention

[0007] This invention addresses the shortcomings of existing constant-frequency AC aggregation modes by providing a variable-frequency AC aggregation method, storage medium, and equipment suitable for direct green electricity connection between wind and solar power clusters and a single user. The method selects the optimal nominal AC voltage value based on the power generation capacity of the wind and solar power cluster. It also divides the primary frequency regulation operating zone and the secondary frequency regulation target optimization range based on the matching status of power generation fluctuations and load. Furthermore, it sets the start-up range and adjustment mode of the automatic voltage regulator according to the frequency regulation operating mode. This method can adapt to the aggregation needs of wind and solar power clusters of different capacities, effectively improving the operational stability, security, and power quality of the aggregation system. It achieves efficient and controllable coupling between wind and solar power clusters and power users, possessing practical, replicable, and scalable engineering application value.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a variable frequency AC aggregation method for direct green electricity connection to a single user, applied to wind and solar power clusters. The optimal nominal voltage of the aggregation AC bus is selected based on the power generation capacity of the wind and solar power cluster. The frequency regulation operation mode is determined based on the matching degree between power generation and load power. Then, the start-up range and adjustment mode of the automatic voltage regulator are set according to the frequency regulation operation mode. In the frequency regulation operation mode setting, the wind and solar power cluster is divided into four zones according to its operating status: normal zone, warning zone, extreme zone, and collapse zone.

[0009] The normal operating range is [16.7Hz, 60Hz], and the allowable voltage fluctuation range is ±10% of the rated voltage.

[0010] The warning zone has an operating frequency range of [15Hz, 65Hz] and an allowable voltage fluctuation range of ±15% of the rated voltage.

[0011] The extreme zone refers to an operating frequency range of <15Hz or >65Hz, with a duration of <100ms, which is considered an abnormal operating state.

[0012] The crash zone: After entering the limit zone, the voltage continues to drop or surge at a rate exceeding 0.1 pu / s;

[0013] When the wind and solar power cluster is operating in the normal or warning zone, normal frequency and voltage regulation is implemented; when the wind and solar power cluster is operating in the extreme zone, frequency and voltage are quickly restored to a safe range; when the wind and solar power cluster is operating in the collapse zone, shutdown protection is implemented.

[0014] As an improvement to the present invention, the method for selecting the optimal nominal voltage of the AC bus based on the power generation capacity of the wind and solar power generation cluster is as follows:

[0015] When the generating capacity of a wind and solar power cluster is in the MW level, the optimal nominal voltage is 10kV;

[0016] When the generating capacity of a wind and solar power cluster is in the hundreds of MW range, the optimal nominal voltage is 35kV.

[0017] When the generating capacity of a wind and solar power cluster is in the GW range, the optimal nominal voltage is 110kV.

[0018] As another improvement of the present invention, the frequency regulation operation mode is divided into primary frequency regulation and secondary frequency regulation. When the power generation of the wind and solar power generation cluster does not match the load power, it enters the primary frequency regulation operation mode. The allowable operating frequency range of the wind and solar power generation cluster is set to [16.7Hz, 60Hz], and primary frequency regulation control is performed within this frequency range.

[0019] When the power generation and load power of the wind and solar power cluster reach a dynamic balance after the first frequency regulation, the system switches to the second frequency regulation mode, and sets the frequency range of the wind and solar power cluster to [49Hz, 51Hz], and performs second frequency regulation optimization control within this frequency range.

[0020] As another improvement of the present invention, it also includes harmonic suppression and power factor correction based on the power quality of the collecting bus, wherein the determination of the power quality of the collecting bus includes at least voltage, current, harmonic content, and power factor.

[0021] When the variable frequency AC aggregation system is in steady-state operation, the total harmonic distortion (THD) of the system is monitored in real time. If the steady-state THD exceeds 10%, characteristic subharmonic components are filtered out to ensure that the steady-state THD is ≤10%. When the wind and solar power cluster experiences transient processes, the transient harmonic components are monitored in real time. If the transient THD exceeds 15%, the response speed and compensation depth of harmonic suppression are improved to ensure that the transient THD is ≤15%.

[0022] The system monitors the active and reactive power of the variable frequency AC collection system in real time, calculates the system power factor, and dynamically adjusts the reactive power output under full load conditions to achieve a balance compensation of capacitive and inductive reactive power, ensuring that the power factor of the system is ≥0.9 under full load conditions.

[0023] As a further improvement of the present invention, it also includes determining the operating mode of the energy storage device according to the needs of the busbar connecting to the public power grid; performing closed-loop adjustment and synchronous tracking of the output parameters of the wind and solar power generation cluster, dynamically correcting the deviation between the output parameters and the reference parameters of the public power grid until the two are consistent, and performing grid connection operation; the output parameters include at least the output voltage, frequency and phase of the wind and solar power generation cluster.

[0024] To achieve the above objectives, the present invention also adopts the following technical solution: a non-transitory machine-readable storage medium storing executable code thereon, wherein when the executable code is executed by a processor of an electronic device, the processor executes a variable frequency AC aggregation method for direct green electricity connection to a single user as described in any of the preceding claims.

[0025] To achieve the above objectives, the present invention also adopts the following technical solution: a computer device, comprising:

[0026] Memory, on which executable code is stored;

[0027] A processor is configured to execute the executable code, causing the computer device to perform the operation of a variable frequency AC aggregation method for direct green electricity connection to a single user as claimed in any of the preceding claims.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) The method of the present invention enhances the flexibility of the variable frequency AC collection system. The wide range of frequency adjustment enables the variable frequency AC collection system to adapt to the strong fluctuations of wind and solar power generation. In the primary frequency regulation stage, the power generation is fully utilized to reduce wind and solar curtailment. In the secondary frequency regulation stage, the frequency is stabilized near the power frequency, ensuring the stable operation of the load equipment.

[0030] (2) The method of the present invention improves the safety of the variable frequency AC collection system. The different operating states provide clear operating boundaries and hierarchical early warning mechanisms. With the corresponding control strategies, it can effectively prevent system crashes and equipment damage, and improve the system's anti-interference and reliability.

[0031] (3) The power quality standards involved in the method of the present invention provide a basis for system design and operation, and the relevant indicators meet the high standard requirements for industrial power consumption.

[0032] (4) The method of the present invention has the ability to achieve smooth grid connection. By adjusting the voltage and frequency, it realizes the smooth coupling between the wind and solar power generation cluster and the public power grid, reduces the grid connection impact, and improves the grid's acceptance capacity. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the steps of a variable frequency AC aggregation method for direct green electricity connection to a single user according to the present invention.

[0034] Figure 2 This is a flowchart of the step S1 of the method of the present invention for selecting the nominal voltage of the AC bus.

[0035] Figure 3 This is a flowchart of the steps for adjusting the AC bus frequency in step S2 of the method of the present invention;

[0036] Figure 4 This is a schematic diagram of the wind and solar power cluster frequency conversion AC collection hydrogen production system of the present invention. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] Example 1

[0039] A method for directly connecting green electricity to a single user via variable frequency AC aggregation, such as... Figure 1 As shown, the specific steps include the following:

[0040] Step S1: Select the optimal nominal voltage of the AC bus based on the power generation capacity of the wind-solar cluster unit.

[0041] Figure 2 This is a flowchart illustrating the method for selecting the nominal AC bus voltage. When the installed capacity of a wind and solar power cluster unit is in the MW level, 10kV is selected as the nominal AC voltage value; when the installed capacity of a wind and solar power cluster unit is in the hundreds of MW level, 35kV is selected as the nominal AC voltage value; and when the installed capacity of a wind and solar power cluster unit is in the GW level, 110kV is selected as the nominal AC voltage value.

[0042] Step S2: Determine the frequency regulation operation mode based on the matching degree between power generation and load power. Figure 3 The diagram shows a flowchart of the AC bus frequency adjustment process.

[0043] First, it is determined whether the power generation of the wind and solar power cluster unit matches the load power. When the power generation of the wind and solar power cluster unit is mismatched with the load power due to power generation fluctuations or load start-stop, it enters the primary frequency regulation operation mode. The allowable operating frequency range of the wind and solar power cluster unit is set to [16.7Hz, 60Hz], and primary frequency regulation control is performed within this frequency range. When the load power > k1 × power generation, the primary frequency regulation range is [16.7Hz, 49Hz], where k1 is usually taken as 1.1; when the load power < k2 × power generation, the primary frequency regulation range is [51Hz, 60Hz], where k2 is usually taken as 0.9.

[0044] When the power generation and load power of the wind and solar power cluster unit reach a dynamic balance after the first frequency regulation, the system switches to the second frequency regulation mode. The frequency optimization target range of the wind and solar power cluster unit is set to [49Hz, 51Hz], and the second frequency regulation optimization control is performed within this frequency range.

[0045] Based on the frequency constraints of the primary and secondary frequency regulation intervals, the output power of the wind and solar power generation cluster units is adjusted in a closed loop to achieve system frequency stability and power balance.

[0046] Step S3: Set the start-up range and adjustment mode of the automatic voltage regulator according to the frequency modulation mode.

[0047] In this step, based on the operating frequency and voltage fluctuation characteristics, the operating area of ​​the wind-solar power generation cluster system is divided into four zones according to its operating status: normal zone, warning zone, extreme zone, and collapse zone. Specifically: the normal zone has an operating frequency range of [16.7Hz, 60Hz], the same as the primary frequency regulation range, and the allowable voltage fluctuation range is ±10% of the rated voltage; the warning zone has an operating frequency range of [15Hz, 65Hz], and the allowable voltage fluctuation range is ±15% of the rated voltage; the extreme zone has an operating frequency <15Hz or >65Hz, and a duration <100ms, indicating an abnormal operating state; and when the system enters the extreme zone, if the voltage continues to drop or surges at a rate exceeding 0.1 pu / s, it enters the collapse zone.

[0048] Based on the frequency regulation mode and operating area, the start-up range and regulation strategy of the automatic voltage regulator are set. When the system is in the normal or warning zone, conventional frequency and voltage regulation control is used; when the system enters the extreme zone, emergency regulation measures are activated to quickly restore the frequency and voltage to a safe range; when the system is determined to have entered the collapse zone, the wind and solar power cluster aggregation system is controlled to perform shutdown protection.

[0049] In addition, the method of the present invention also includes harmonic suppression and power factor correction based on the power quality of the bus. Power quality parameters such as voltage, current, harmonic content, and power factor of the bus in the variable frequency AC bus system are collected in real time, and harmonic suppression and power factor correction are performed based on the power quality.

[0050] Steady-state total harmonic distortion rate adjustment: When the variable frequency AC collection system is in steady-state operation, the total harmonic distortion rate of the system is monitored in real time. If the steady-state total harmonic distortion rate exceeds 10%, dynamic compensation is performed through the active filter unit or passive filter branch in the harmonic suppression device to filter out characteristic subharmonic components, so that the steady-state total harmonic distortion rate of the system is ≤10%.

[0051] Transient total harmonic distortion rate adjustment: When the wind and solar power generation cluster experiences transient processes such as power fluctuations, load changes, or grid connection switching, the transient harmonic components are monitored in real time. If the transient total harmonic distortion rate exceeds 15%, the transient harmonic impact is quickly suppressed by improving the response speed and compensation depth of the harmonic suppression device, so that the transient total harmonic distortion rate of the system is ≤15%.

[0052] Power factor regulation: Real-time detection of active and reactive power of the variable frequency AC collection system, calculation of system power factor, and dynamic adjustment of reactive power output through power factor correction device under full load conditions to achieve balanced compensation of capacitive and inductive reactive power, ensuring that the power factor is ≥0.9 under full load conditions.

[0053] In order to connect the busbar to the public power grid, the first step is to collect key electrical parameters such as the rated voltage amplitude, frequency, and phase of the public power grid in real time as reference parameters for grid connection regulation, so as to ensure that the regulation direction matches the operating parameters of the public power grid.

[0054] Then, parameter adjustments are made, and the power electronic converter in the photovoltaic-storage-charging integrated equipment is started to perform closed-loop adjustment and synchronous tracking of the output voltage amplitude, frequency and phase of the wind and solar power generation cluster unit collection system. The deviation between the collection system output parameters and the public grid reference parameters is dynamically corrected until the two are consistent and the conditions for synchronous grid connection are met.

[0055] Finally, after completing the grid connection operation and confirming that the output parameters of the aggregation system are fully matched with the rated parameters of the public power grid and that the synchronization conditions are met, the grid connection operation is executed to smoothly connect the wind and solar power cluster unit aggregation system to the public power grid, achieving a safe, stable, and seamless coupling connection between the two, and ensuring that the system operation is not impacted during the grid connection process. Figure 4 As shown, Figure 4 This is a schematic diagram of a variable frequency AC aggregation hydrogen production system for a wind and solar power cluster. In this system, wind power, solar power, and energy storage are connected to an AC aggregation bus. The hydrogen production system is connected to the AC bus as an electrical load. When not connected to the public grid, the frequency of the AC aggregation bus is actively adjusted by the power electronic converters of the wind and solar power generation units based on the power generation and load power. When connected to the public grid, the aggregation voltage amplitude and frequency are first adjusted to the rated voltage amplitude and frequency of the public grid through the power electronic converter of the energy storage equipment, and then the wind and solar power cluster unit aggregation system is connected to the public grid.

[0056] In summary, this invention discloses a variable frequency AC voltage / frequency regulation method applicable to the direct connection of wind and solar power clusters to a single user. It aims to solve the technical problems of unreasonable voltage amplitude and frequency matching during the aggregation process of wind and solar power clusters, as well as the difficulty in ensuring safe operation and power quality. This provides support for the efficient aggregation and stable grid connection of wind and solar power clusters of different capacities. The method of this invention can reduce losses, reduce equipment investment, improve power supply stability and wind and solar power absorption rate, adapt to the aggregation needs of wind and solar power clusters of different capacities, effectively improve the operational stability, safety and power quality of the aggregation system, and achieve efficient and controllable coupling between wind and solar power clusters and the public power grid.

[0057] Example 2

[0058] This embodiment provides a non-transitory machine-readable storage device that stores executable code. When the executable code is executed by a processor of an electronic device, the processor performs the method described in the above embodiment.

[0059] A non-transitory machine-readable storage device (or computer-readable storage device, or machine-readable memory) storing executable code (or computer program, or computer instruction code) that, when executed by a processor of an electronic device (or computing device, server, etc.), causes the processor to perform the steps of the method described above according to the present invention.

[0060] Example 3

[0061] This embodiment discloses a computer device, including a processor and a memory, wherein the memory stores code for executing the methods described in the above embodiment.

[0062] The processor can be a multi-core processor or may contain multiple processors. In some embodiments, the processor may include a general-purpose main processor and one or more specialized coprocessors, such as a graphics processing unit (GPU), a digital signal processor (DSP), etc. In some embodiments, the processor may be implemented using custom circuitry, such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[0063] Memory can include various types of storage units, such as system memory, read-only memory (ROM), and permanent storage devices. ROM can store static data or instructions required by the processor or other modules of the computer. Permanent storage devices can be read-write storage devices. Permanent storage devices can be non-volatile storage devices that retain stored instructions and data even when the computer is powered off. In some embodiments, permanent storage devices use high-capacity storage devices (e.g., magnetic or optical disks, flash memory) as permanent storage devices. In other embodiments, permanent storage devices can be removable storage devices (e.g., floppy disks, optical drives). System memory can be a read-write storage device or a volatile read-write storage device, such as dynamic random access memory. System memory can store some or all of the instructions and data required by the processor during operation. Furthermore, memory can include any combination of computer-readable storage media, including various types of semiconductor memory chips (DRAM, SRAM, SDRAM, flash memory, programmable read-only memory), and disks and / or optical disks can also be used. In some implementations, the memory may include removable storage devices that are readable and / or writable, such as laser discs (CDs), read-only digital versatile optical discs (e.g., DVD-ROMs, dual-layer DVD-ROMs), read-only Blu-ray discs, ultra-high density optical discs, flash memory cards (e.g., SD cards, mini SD cards, Micro-SD cards, etc.), magnetic floppy disks, etc. Computer-readable storage media do not contain carrier waves or transient electronic signals transmitted wirelessly or via wired connections.

[0064] The memory stores executable code, which, when executed by the processor, causes the processor to perform the method described above.

[0065] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A method for direct-connection of green electricity to a single user via variable frequency AC aggregation, applied to wind and solar power clusters, characterized in that... The optimal nominal voltage of the AC bus is selected based on the generating capacity of the wind and solar power cluster. The frequency regulation operation mode is determined based on the matching degree between the generating power and the load power. Then, the start-up range and regulation mode of the automatic voltage regulator are set according to the frequency regulation operation mode. In the frequency regulation operation mode setting, the wind and solar power cluster is divided into four areas according to its operating status: normal zone, warning zone, extreme zone, and collapse zone. The normal operating range is [16.7Hz, 60Hz], and the allowable voltage fluctuation range is ±10% of the rated voltage. The warning zone has an operating frequency range of [15Hz, 65Hz] and an allowable voltage fluctuation range of ±15% of the rated voltage. The extreme zone refers to an operating frequency range of <15Hz or >65Hz, with a duration of <100ms, which is considered an abnormal operating state. The crash zone: After entering the limit zone, the voltage continues to drop or surge at a rate exceeding 0.1 pu / s; When the wind and solar power cluster is operating in the normal or warning zone, normal frequency and voltage regulation is implemented; when the wind and solar power cluster is operating in the extreme zone, frequency and voltage are quickly restored to a safe range; when the wind and solar power cluster is operating in the collapse zone, shutdown protection is implemented.

2. The method for direct-connection of green electricity to a single user via frequency conversion AC aggregation as described in claim 1, characterized in that: The specific method for selecting the optimal nominal voltage of the AC bus based on the generating capacity of the wind and solar power cluster is as follows: When the generating capacity of a wind and solar power cluster is in the MW level, the optimal nominal voltage is 10kV; When the generating capacity of a wind and solar power cluster is in the hundreds of MW range, the optimal nominal voltage is 35kV. When the generating capacity of a wind and solar power cluster is in the GW range, the optimal nominal voltage is 110kV.

3. The method for direct-connection of green electricity to a single user via frequency conversion AC aggregation as described in claim 1, characterized in that: The frequency regulation operation mode is divided into primary frequency regulation and secondary frequency regulation. When the power generation of the wind and solar power generation cluster does not match the load power, it enters the primary frequency regulation operation mode. The allowable operating frequency range of the wind and solar power generation cluster is set to [16.7Hz, 60Hz], and primary frequency regulation control is performed within this frequency range. When the load power > k1 × power generation, the primary frequency regulation range is [16.7Hz, 49Hz], and k1 is 1.

1. When the load power < k2 × power generation, the primary frequency regulation range is [51Hz, 60Hz], and k2 is 0.

9. When the power generation and load power of the wind and solar power cluster reach a dynamic balance after the first frequency regulation, the system switches to the second frequency regulation mode, and sets the frequency range of the wind and solar power cluster to [49Hz, 51Hz], and performs second frequency regulation optimization control within this frequency range.

4. The method for direct-connection of green electricity to a single user via frequency conversion AC aggregation as described in claim 1, characterized in that: It also includes harmonic suppression and power factor correction based on the power quality of the busbar, wherein the determination of the power quality of the busbar includes at least voltage, current, harmonic content, and power factor. When the variable frequency AC aggregation system is in steady-state operation, the total harmonic distortion (THD) of the system is monitored in real time. If the steady-state THD exceeds 10%, characteristic subharmonic components are filtered out to ensure that the steady-state THD is ≤10%. When the wind and solar power cluster experiences transient processes, the transient harmonic components are monitored in real time. If the transient THD exceeds 15%, the response speed and compensation depth of harmonic suppression are improved to ensure that the transient THD is ≤15%. The system monitors the active and reactive power of the variable frequency AC collection system in real time, calculates the system power factor, and dynamically adjusts the reactive power output under full load conditions to achieve a balance compensation of capacitive and inductive reactive power, ensuring that the power factor of the system is ≥0.9 under full load conditions.

5. A method for direct-connection of green electricity to a single user via frequency conversion AC aggregation as described in claim 1 or 4, characterized in that: It also includes determining the operating mode of the energy storage device based on the demand for the busbar to connect to the public power grid; performing closed-loop regulation and synchronous tracking of the output parameters of the wind and solar power generation cluster, dynamically correcting the deviation between the output parameters and the public power grid reference parameters until the two are consistent, and performing grid connection operation; the output parameters include at least the output voltage, frequency and phase of the wind and solar power generation cluster.

6. A non-transitory machine-readable storage medium, characterized in that: It stores executable code, which, when executed by the processor of the electronic device, causes the processor to perform a variable frequency AC aggregation method for direct green electricity connection to a single user as described in any one of claims 1-5.

7. A computer device, characterized in that: include: Memory, on which executable code is stored; A processor is configured to execute the executable code, causing the computer device to perform the operation of a variable frequency AC aggregation method for direct green electricity connection to a single user as described in any one of claims 1-5.

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