Starting method of multi-new energy station connected to power grid through flexible DC system

Abstract

The application discloses a starting method for a multi-new-energy station connected to a power grid through a flexible DC system. The method comprises the following steps: under the condition that the flexible DC system is stably operated, setting a converter transformer tap changer to a manual control mode and setting AC voltage of the flexible DC system to a preset control reference value before starting the new-energy station; charging the collection line and the transformer of all the multiple new-energy stations which need to be started one by one; after the multiple new-energy stations are started, setting the AC voltage of the flexible DC system to the AC voltage under the normal operation state of the flexible DC system; setting the converter transformer tap changer to an automatic control mode, and starting the grid-connected power generation of the new-energy station unit one by one.

Description

Technical Field

[0001] This invention relates to the field of new energy power plant access technology, specifically, to a startup method for a scenario in which multiple new energy power plants are connected to the power grid via a flexible DC system. Background Technology

[0002] With the rapid development of new energy sources, there are now various ways to connect them to the power system, such as connecting new energy sources to the AC grid via step-up transformers, bundling wind, solar, and thermal power generation to the AC grid, and connecting isolated new energy sources to the AC grid via flexible DC systems. The different ways new energy sources connect to the grid result in different impacts on the grid during the charging process of the step-up transformer.

[0003] Because the AC grid has sufficient voltage support capacity, the charging of the new energy transformer's step-up transformer has a negligible impact on the AC grid and the new energy generating units in scenarios where new energy is directly connected to the AC grid. However, when new energy is connected to the AC grid via a flexible DC system, the inrush current during transformer charging in the flexible DC islanded substation causes significant disturbances to both the flexible DC system and the new energy generating units due to the weak voltage support capacity of the flexible DC islanded substation. In severe cases, this can lead to the new energy generating units disconnecting from the grid. Therefore, it is essential to optimize the startup method for new energy islanded substations connected via a flexible DC system. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a startup method for a scenario where multiple new energy power plants are connected to the power grid via a flexible DC system.

[0005] According to one aspect of the present invention, a startup method is provided for a scenario in which multiple new energy power plants are connected to the power grid via a flexible DC system, comprising:

[0006] Under the condition that the flexible DC system is operating stably, before starting the new energy power station, set the converter transformer tap changer to manual control mode and set the AC voltage of the flexible DC system to the preset control reference value.

[0007] The charging lines and transformers of all the multiple new energy power stations that need to be started are charged in sequence;

[0008] After multiple new energy power stations have been started up, the AC voltage of the flexible DC system will be set to the AC voltage under normal operating conditions of the flexible DC system.

[0009] Set the converter transformer tap changer to automatic control mode and start the grid-connected power generation of the new energy power station units in sequence.

[0010] Optionally, the flexible DC system operates in voltage-frequency control mode during stable operation, and the converter transformer tap changer operates in automatic control mode.

[0011] Optionally, before starting the new energy power station, the AC voltage of the flexible DC system is set to a preset control reference value, including:

[0012] With all new energy power plants shut down, the AC voltage of the flexible DC system is set to the first preset control reference value.

[0013] When some new energy power stations are in operation and others are out of service, the AC voltage of the flexible DC system is set to the second preset control reference value.

[0014] Optionally, the first preset control reference value is 0.8 pu, and the second preset control reference value is 0.92 pu.

[0015] Optionally, the voltage of the flexible DC system under normal operating conditions is 1.0 pu.

[0016] According to another aspect of the present invention, a starting device is provided for a scenario where multiple new energy power plants are connected to the power grid via a flexible DC system, comprising:

[0017] The setting module is used to set the converter transformer tap changer to manual control mode and set the AC voltage of the flexible DC system to a preset control reference value before starting the new energy power station when the flexible DC system is operating stably.

[0018] The charging module is used to charge the charging lines and transformers of all the multiple new energy power stations that need to be started in sequence;

[0019] The recovery module is used to set the AC voltage of the flexible DC system to the AC voltage under normal operating conditions of the flexible DC system after multiple new energy power stations have been started.

[0020] The startup module is used to set the converter transformer tap changer to automatic control mode and sequentially start the grid-connected power generation of the new energy power station units.

[0021] According to another aspect of the present invention, a computer-readable storage medium is provided, the storage medium storing a computer program for performing the methods described in any of the above aspects of the present invention.

[0022] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0023] Therefore, the startup method for multiple renewable energy power stations connected to the grid via a flexible DC system provided by this invention can effectively reduce the impact of the inrush current of the boost transformer charging at the renewable energy power station to be started on the grid connection point bus voltage by lowering the AC bus voltage at the grid connection point, thus ensuring that the generating units of the operating renewable energy power station maintain stable operation and do not disconnect from the grid. Furthermore, by optimizing the startup sequence of the renewable energy power station, this invention ensures that the renewable energy to be started does not affect the operating renewable energy power station during the startup process. Attached Figure Description

[0024] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0025] Figure 1 This is a flowchart illustrating a startup method for a scenario where multiple new energy power stations are connected to the power grid via a flexible DC system, provided by an exemplary embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of a scenario provided by an exemplary embodiment of the present invention, in which all new energy power stations are started from a shutdown state;

[0027] Figure 3 This is a schematic diagram of the startup process of a new energy power station in a scenario where all power stations are started from a shutdown state, provided by an exemplary embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram illustrating a scenario provided by an exemplary embodiment of the present invention, in which some new energy power stations are in operation and others are started from a shutdown state.

[0029] Figure 5 This is a flowchart of the startup process for a portion of the new energy power stations under an exemplary embodiment of the present invention, where the other portion of the new energy power stations are started from a shutdown state.

[0030] Figure 6 This is an exemplary embodiment of the present invention, which provides a simulation waveform of the effect of the inrush current of the step-up transformer of a new energy power station on the AC bus voltage when the reference value of the AC bus voltage at the grid connection point is not reduced (from top to bottom: three-phase voltage of the AC bus at the grid connection point, three-phase current of the AC bus, flexible DC voltage, flexible DC power, harmonic spectrum of the three-phase voltage of the AC bus at the grid connection point, and harmonic spectrum of the three-phase current of the AC bus).

[0031] Figure 7 This is an exemplary embodiment of the present invention, which provides simulation waveforms of the effect of inrush current of a step-up transformer charging at a new energy power station on AC bus voltage when the reference value of the AC bus voltage at the grid connection point is reduced to 0.92 pu (from top to bottom: three-phase AC bus voltage at the grid connection point, three-phase AC bus current, flexible DC voltage, flexible DC power, harmonic spectrum of three-phase AC bus voltage at the grid connection point, and harmonic spectrum of three-phase AC bus current).

[0032] Figure 8 This is a schematic diagram of the structure of the starting device for a scenario where multiple new energy power stations are connected to the power grid via a flexible DC system, provided in an exemplary embodiment of the present invention;

[0033] Figure 9 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. Detailed Implementation

[0034] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0035] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0036] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0037] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0038] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0039] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0040] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0041] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0042] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0043] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0044] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0045] Exemplary methods

[0046] Figure 1 This is a flowchart illustrating a startup method for a multi-energy power plant connected to the power grid via a flexible DC system, provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as… Figure 1 As shown, the startup method 100 for a scenario where multiple new energy power plants are connected to the power grid via a flexible DC system includes the following steps:

[0047] Step 101: Under the condition that the flexible DC system is operating stably, before starting the new energy power station, set the converter transformer tap changer to manual control mode and set the AC voltage of the flexible DC system to the preset control reference value.

[0048] Step 102: Charge the collection lines and transformers of all the multiple new energy power stations that need to be started in sequence;

[0049] Step 103: After multiple new energy power stations have been started up, set the AC voltage of the flexible DC system to the AC voltage under normal operating conditions of the flexible DC system.

[0050] Step 104: Set the converter transformer tap changer to automatic control mode and start the grid-connected power generation of the new energy power station units in sequence.

[0051] Optionally, the flexible DC system operates in voltage-frequency control mode during stable operation, and the converter transformer tap changer operates in automatic control mode.

[0052] Optionally, before starting the new energy power station, the AC voltage of the flexible DC system is set to a preset control reference value, including:

[0053] With all new energy power plants shut down, the AC voltage of the flexible DC system is set to the first preset control reference value.

[0054] When some new energy power stations are in operation and others are out of service, the AC voltage of the flexible DC system is set to the second preset control reference value.

[0055] Optionally, the first preset control reference value is 0.8 pu, and the second preset control reference value is 0.92 pu.

[0056] Optionally, the voltage of the flexible DC system under normal operating conditions is 1.0 pu.

[0057] Specifically, in scenarios where isolated renewable energy systems are connected to the grid via a flexible DC system, the bus voltage of the flexible DC system serves as the reference voltage for the renewable energy grid connection point. Due to the low inertia of the flexible DC system, its bus voltage has weak anti-disturbance capability. Therefore, the inrush current generated by the charging of the renewable energy step-up transformer in its vicinity can severely affect the bus voltage, causing serious distortion and thus affecting the normal operation of the renewable energy units in operation. In severe cases, it can even cause the renewable energy units to disconnect from the grid. This invention reduces the bus voltage level at the grid connection point, thereby reducing the inrush current during the charging of the renewable energy step-up transformer, and consequently reducing the impact of the inrush current on the bus voltage at the grid connection point and on the control and protection of the flexible DC system.

[0058] Among them, the flexible DC system can be the flexible DC system for isolated stations.

[0059] Due to the conversion of electrical and magnetic energy in the transformer, the phase angle of the voltage at the moment of closing, and the saturation degree of the iron core, there is an inrush current when the transformer is closed. The magnitude of the inrush current is affected by the residual magnetism of the iron core, the iron core material, and the amplitude and phase of the voltage. Therefore, when it is inconvenient to change the residual magnetism of the iron core, the iron core material, and the closing phase on site, the inrush current during transformer charging can be reduced by changing the voltage amplitude, i.e., the voltage amplitude of the bus at the grid connection point. According to the relationship between the induced electromotive force and magnetic flux of the transformer coil, there is the expression shown in formula (1).

[0060] E=4.44fNφ(1)

[0061] Where: E is the effective value of the induced electromotive force (volts), f is the AC frequency (hertz), N is the number of turns in the winding, and φ is the magnetic flux amplitude (Weber). According to the relationship in formula (1), when the frequency and the number of turns in the winding remain unchanged, the induced electromotive force decreases, the magnetic flux decreases, and thus the inrush current of the transformer charging excitation decreases.

[0062] Before starting up a new energy power station, it is necessary to determine the bus voltage regulation range and regulation method based on the low voltage level of the new energy, the control mode of the flexible DC system, and the output AC voltage level, so as to ensure that the new energy units already in operation will not disconnect from the grid due to low bus voltage at the grid connection point.

[0063] Consider two common startup methods for isolated renewable energy power stations: (1) all renewable energy power stations are started from a shutdown state; (2) some renewable energy power stations are already in operation, while others are started from a shutdown state. The startup methods for the two scenarios are basically the same, but the first scenario can reduce the voltage at the grid connection point to be lower.

[0064] Specifically, Figure 2 This is a schematic diagram illustrating a scenario where all new energy power stations start from a shutdown state. In scenario 1, all new energy power stations start from a shutdown state. Figure 1 A schematic diagram of the startup process is given, taking the startup of three new energy power stations as an example. The equipment on the right is the operating equipment. The corresponding operations are performed in sequence according to the serial number to start the new energy power station.

[0065] refer to Figure 3 As shown, the startup process for scenario 1 follows these steps:

[0066] 1) First, ensure that the flexible DC system is operating stably and in V / F control mode, and that the converter transformer tap changer of the flexible DC system is in automatic control mode.

[0067] 2) All new energy power stations are currently shut down;

[0068] 3) Before starting the new energy power station, in order to reduce the impact of transformer charging excitation inrush current on the control and protection of the flexible DC system, especially on the related protection of the converter valve, the converter transformer tap changer of the flexible DC system should be set to manual control mode, and the AC voltage reference value of the flexible DC system should be set to a small reference value (e.g., the AC voltage reference value should be set to 0.8pu).

[0069] 4) Charge the collection lines and step-up transformers of the first to nth new energy power stations in sequence;

[0070] 5) Restore the AC voltage reference value of the flexible DC system to 1.0 pu, and set the converter transformer tap changer to automatic control mode;

[0071] 6) Start up and connect all new energy power station units to the grid in sequence.

[0072] Furthermore, Figure 4 This is a schematic diagram illustrating a scenario where some renewable energy power stations are operating while others are starting up from a shutdown state. In scenario 2, some renewable energy power stations are operating while others are starting up from a shutdown state. Figure 4 A schematic diagram of the startup process is given, taking the startup of two new energy power stations as an example. The equipment on the right is the operating equipment. The corresponding operations are performed in sequence according to the serial number to start the new energy power station.

[0073] refer to Figure 5 As shown, the startup process for scenario 2 is as follows:

[0074] 1) First, ensure that the flexible DC system is operating stably and in V / F control mode, and that the converter transformer tap changer of the flexible DC system is in automatic control mode;

[0075] 2) The power generation operations of the new energy power plants in operation are stable;

[0076] 3) The converter transformer tap changer of the flexible DC system is set to manual control mode;

[0077] 4) Before starting a new energy power station, in order to reduce the impact of transformer charging excitation inrush current on the operating new energy power station units, it is necessary to set the AC voltage reference value of the flexible DC system according to the voltage limit of the low voltage ride-through of the new energy units. At the same time, voltage fluctuations should be taken into account, and the AC voltage reference value should be appropriately larger than the low voltage ride-through value of the new energy units, such as 0.92pu.

[0078] 5) Charge the charging lines and step-up transformers of the first to nth new energy power stations in sequence;

[0079] 6) Restore the AC voltage reference value to 1.0 pu and set the converter transformer tap changer to automatic control mode;

[0080] 7) Start up and connect all the new energy power station units to the grid in sequence.

[0081] Furthermore, this invention proposes a startup method to reduce the impact of inrush current during transformer charging at a renewable energy islanding station on the AC bus voltage at the grid connection point. By reducing the AC bus voltage, the inrush current during transformer charging can be effectively reduced, thereby reducing the degree of distortion of the AC bus voltage caused by the inrush current. This can effectively ensure the stable operation of renewable energy islanding stations connected to the grid and reduce the risk of grid disconnection of the generating units at renewable energy stations.

[0082] To verify the effectiveness of this invention, a simulation experiment was conducted on a hybrid power system simulation platform based on the Zhangbei flexible DC transmission project. This was done using the same closing angle, residual magnetism level, and transformer model as the step-up transformer at a certain renewable energy power station. Figure 6 and Figure 7 The waveforms were simulated and verified using both the method proposed in this invention and without it. Figure 6 and Figure 7 The simulation waveforms show that, under the same operating conditions, when the reference value of the AC voltage at the grid connection point is reduced to 0.92 pu as proposed in this invention, the impact of the inrush current of the step-up transformer at a certain new energy power station on the AC bus voltage at the grid connection point is significantly reduced, ensuring the stable operation of the new energy power station units without disconnection from the grid, thus verifying the effectiveness of this invention.

[0083] Therefore, the startup method for multiple renewable energy power plants connected to the grid via a flexible DC system provided by this invention can effectively reduce the impact of the inrush current of the boost transformer charging at the renewable energy grid connection point on the grid connection point by lowering the AC bus voltage at the renewable energy grid connection point of the islanded power plant, thus ensuring that the generating units of the operating renewable energy power plants maintain stable operation and do not disconnect from the grid. This invention optimizes the startup sequence of renewable energy power plants, ensuring that the renewable energy to be started does not affect the operating renewable energy power plants during the startup process.

[0084] Exemplary device

[0085] Figure 8 This is a schematic diagram of the starting device for a scenario where multiple new energy power stations are connected to the power grid via a flexible DC system, provided by an exemplary embodiment of the present invention. Figure 8 As shown, the device 800 includes:

[0086] Setting module 810 is used to set the converter transformer tap changer to manual control mode and set the AC voltage of the flexible DC system to a preset control reference value before starting the new energy power station when the flexible DC system is operating stably.

[0087] The charging module 820 is used to charge the collection lines and transformers of all the multiple new energy power stations that need to be started in sequence.

[0088] The recovery module 830 is used to set the AC voltage of the flexible DC system to the AC voltage under normal operating conditions of the flexible DC system after multiple new energy power stations have been started.

[0089] The startup module 840 is used to set the converter transformer tap changer to automatic control mode and sequentially start the grid-connected power generation of the new energy power station units.

[0090] Optionally, the flexible DC system in module 810 is set to voltage-frequency control mode during stable operation, and the converter transformer tap changer is set to automatic control mode.

[0091] Optionally, the setting module 810 includes:

[0092] The first setting submodule is used to set the AC voltage of the flexible DC system to a first preset control reference value when all new energy power stations are out of service.

[0093] The second setting submodule is used to set the AC voltage of the flexible DC system to a second preset control reference value when some of the new energy power stations are in operation and the other part of the new energy power stations are out of service.

[0094] Optionally, the first preset control reference value in the first setting submodule is 0.8pu, and the second preset control reference value in the second setting submodule is 0.92pu.

[0095] Optionally, the voltage of the flexible DC system in the recovery module 830 under normal operating conditions is 1.0 pu.

[0096] Exemplary electronic devices

[0097] Figure 9 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. For example... Figure 9 As shown, the electronic device 90 includes one or more processors 91 and memory 92.

[0098] The processor 91 may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0099] The memory 92 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 91 may execute the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above, and / or other desired functions. In one example, the electronic device may also include an input device 93 and an output device 94, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0100] In addition, the input device 93 may also include, for example, a keyboard, a mouse, etc.

[0101] The output device 94 can output various information to the outside. The output device 94 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0102] Of course, for the sake of simplicity, Figure 9 Only some of the components of this electronic device relevant to the present invention are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0103] Exemplary computer program products and computer-readable storage media

[0104] In addition to the methods and apparatus described above, embodiments of the present invention may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0105] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of the present invention. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0106] Furthermore, embodiments of the present invention may also be computer-readable storage media storing computer program instructions thereon, which, when executed by a processor, cause the processor to perform the steps of the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0107] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0108] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0109] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0110] The block diagrams of devices, systems, devices, and systems involved in this invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, systems, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0111] The methods and systems of the present invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of the present invention are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, the present invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers recording media storing programs for performing the methods according to the present invention.

[0112] It should also be noted that in the systems, apparatus, and methods of the present invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalents of the present invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0113] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A startup method for a scenario where multiple new energy power plants are connected to the power grid via a flexible DC system, characterized in that, include: Under the condition that the flexible DC system is operating stably, before starting the new energy power station, set the converter transformer tap changer to manual control mode and set the AC voltage of the flexible DC system to a preset control reference value; The charging lines and transformers of all the aforementioned new energy power stations that need to be started are charged in sequence; After the multiple new energy power stations have been started up, the AC voltage of the flexible DC system is set to the AC voltage of the flexible DC system under normal operating conditions. Set the converter transformer tap changer to automatic control mode and start the grid-connected power generation of the new energy power station units in sequence; Before starting the new energy power station, the AC voltage of the flexible DC system is set to a preset control reference value, including: When all the aforementioned new energy power stations are out of service, the AC voltage of the flexible DC system is set to a first preset control reference value; When some of the new energy power stations are in operation and the other are out of service, the AC voltage of the flexible DC system is set to a second preset control reference value. The first preset control reference value is 0.8 pu, and the second preset control reference value is 0.92 pu; The AC voltage of the flexible DC system under normal operating conditions is 1.0 pu.

2. The method according to claim 1, characterized in that, The flexible DC system operates in voltage and frequency control mode during stable operation, and the converter transformer tap changer operates in automatic control mode.

3. A starting device for a scenario where multiple new energy power stations are connected to the power grid via a flexible DC system, used to implement the method described in claim 1, characterized in that, include: The setting module is used to set the converter transformer tap changer to manual control mode and set the AC voltage of the flexible DC system to a preset control reference value before starting the new energy power station under the condition that the flexible DC system is operating stably. The charging module is used to charge the collection lines and transformers of all the multiple new energy power stations that need to be started in sequence; The recovery module is used to set the AC voltage of the flexible DC system to the AC voltage of the flexible DC system under normal operating conditions after the multiple new energy power stations have been started. The startup module is used to set the converter transformer tap changer to automatic control mode and sequentially start the grid-connected power generation of the new energy power station units.

4. The apparatus according to claim 3, characterized in that, The flexible DC system in the setting module operates in voltage-frequency control mode during stable operation, and the converter transformer tap changer operates in automatic control mode.

5. A computer-readable storage medium, characterized in that, The storage medium stores a computer program for performing the method described in any one of claims 1-2.

6. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1-2.

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