A dynamic coordination method for flexible direct current co-frequency control and normal direct current single-side FLC coordinated control and voltage support

Abstract

The present application relates to the technical field of power system stability and control, and provides a method for the dynamic coordination of flexible direct current co-frequency control and conventional direct current single-side FLC coordinated control and voltage support. The method obtains the flexible direct current power adjustment amount through the sending-end grid frequency, the receiving-end grid frequency and the system frequency reference value; then, when the flexible direct current power adjustment amount exceeds the preset limit range, and the system frequency deviation exceeds the preset frequency control dead zone, the conventional direct current power adjustment amount is output based on the sending-end grid frequency and the system frequency reference value; and then, reactive power support is provided based on the conventional direct current power adjustment amount and the original reactive power reference value of the VSC. The rapid controllability of the direct current transmission system is fully utilized. The flexible direct current adopts flexible direct current co-frequency control, and the conventional direct current adopts single-side FLC control, which quickly balances the system active power shortage, participates in the primary frequency regulation of the power grid, and effectively improves the purpose of system frequency stability.

Description

Technical Field

[0001] The present application relates to the technical field of power system stability and control, and in particular to a method for dynamically coordinating flexible direct current co-frequency control with single-side FLC coordinated control of a normal direct current and voltage support. Background Art

[0002] Large-scale AC / DC hybrid synchronous power grid system refers to the combination of traditional AC transmission system and high-voltage DC transmission system to form a unified, efficient and reliable power transmission network. This system can realize long-distance and large-capacity power transmission, and has good regulation performance and economy.

[0003] However, the traditional large-scale AC / DC hybrid synchronous power grid system is prone to problems such as excessive short-circuit current, fault propagation, and low-frequency oscillation during operation. Therefore, DC asynchronous networking is usually used in large-scale AC / DC hybrid synchronous power grid systems to limit the short-circuit current level and eliminate the possibility of low-frequency oscillation from the network structure, as well as to block the transmission of AC faults in the network structure.

[0004] However, after the large-scale AC / DC hybrid synchronous power grid system is interconnected through DC asynchronous interconnection, the rotational inertia and frequency regulation capacity of the original synchronous power grid will be split, which will cause the rotational inertia and frequency regulation capacity of each subsystem to be much smaller than the entire system, making the frequency stability problem of the asynchronous regional power grid the main stability problem of the asynchronous regional power grid. Summary of the invention

[0005] In view of the above, it is necessary to provide a dynamic coordination method of flexible direct current co-frequency control and normal direct current single-side FLC coordinated control and voltage support, which can solve the technical problem of insufficient frequency stability of asynchronous regional power grid.

[0006] On the one hand, the present application proposes a method for dynamically coordinating flexible direct current co-frequency control with normally direct current single-side FLC coordinated control and voltage support, the method comprising:

[0007] Based on the sending-end grid frequency, the receiving-end grid frequency and the system frequency reference value, the flexible direct current power regulation amount is obtained;

[0008] When the flexible direct current power regulation amount exceeds the preset limit range and the system frequency deviation exceeds the preset frequency control dead zone, outputting the normal direct current power regulation amount based on the sending-end grid frequency and the system frequency reference value;

[0009] Based on the constant direct power adjustment amount and the original reactive power reference value of the VSC, reactive power support is provided.

[0010] In some embodiments of the present application, the step of obtaining the flexible direct current power adjustment amount based on the sending-end power grid frequency, the receiving-end power grid frequency and the system frequency reference value includes:

[0011] Determine the difference between the power grid frequency at the sending end and the system frequency reference value, and determine the difference between the power grid frequency at the receiving end and the system frequency reference value;

[0012] The difference between the sending-end power grid frequency and the system frequency reference value and the difference between the receiving-end power grid frequency and the system frequency reference value are respectively subjected to filtering operation, DC isolation operation, PI control operation and amplitude limiting operation to obtain the flexible DC power adjustment amount.

[0013] In some embodiments of the present application, after the step of obtaining the flexible direct current power adjustment amount based on the sending-end power grid frequency, the receiving-end power grid frequency and the system frequency reference value, the following further comprises:

[0014] The flexible DC power adjustment amount and the flexible DC original power reference value are superimposed to obtain a VSC active power instruction;

[0015] Based on the VSC active power instruction and the flexible DC power adjustment range, the actual operating power of the flexible DC is adjusted.

[0016] In some embodiments of the present application, before the step of adjusting the actual operating power of the flexible direct current based on the VSC active power instruction and the flexible direct current power adjustment amount range, the step further includes:

[0017] Determine the upper limit of the flexible DC power adjustment range according to the flexible DC power rating, the flexible DC actual operating power and the flexible DC overload capacity coefficient;

[0018] Determine the lower limit of the flexible DC power adjustment amount range according to the flexible DC power rated value, the flexible DC actual operating power and the flexible DC power minimum operating level coefficient;

[0019] The flexible direct current power adjustment amount range is determined based on the upper limit of the flexible direct current power adjustment amount range and the lower limit of the flexible direct current power adjustment amount range.

[0020] In some embodiments of the present application, when the flexible direct current power adjustment amount exceeds the preset limit range and the system frequency deviation exceeds the preset frequency control dead zone, after the step of outputting the normal direct current power adjustment amount based on the sending-end grid frequency and the system frequency reference value, the step further includes:

[0021] Performing logic judgment, per-unit processing, and PI control on the normally direct power adjustment amount to obtain a trigger angle adjustment amount corresponding to the normally direct power adjustment amount;

[0022] The actual operating power of the conventional direct current is adjusted according to the trigger angle adjustment amount and the normal direct current power adjustment amount range.

[0023] In some embodiments of the present application, the step of providing reactive power support based on the constant direct power adjustment amount and the VSC original reactive power reference value includes:

[0024] Performing a power factor calculation operation on the normal direct power regulation amount to obtain a VSC additional reactive power regulation amount;

[0025] Superimposing the VSC additional reactive power adjustment amount and the VSC original reactive power instruction to obtain an updated VSC reactive power instruction;

[0026] Based on the updated VSC reactive power instruction, reactive power support is provided, wherein the reactive power support includes adjusting the reactive power generated by the flexible direct current.

[0027] In some embodiments of the present application, the step of performing a power factor calculation operation on the normal direct power regulation amount to obtain a VSC additional reactive power regulation amount includes:

[0028] Determine the tangent value of the power factor measured by a conventional DC valve connected to a flexible DC;

[0029] A product operation is performed on the tangent value and the constant direct power adjustment amount to obtain the VSC additional reactive power adjustment amount.

[0030] On the other hand, the present application also proposes an AC / DC hybrid synchronous power grid system, comprising:

[0031] A flexible direct current frequency control unit is used to obtain a flexible direct current power adjustment amount based on the sending-end grid frequency, the receiving-end grid frequency and the system frequency reference value;

[0032] A single-side FLC control unit for the flexible direct current, used to output a normal direct current power adjustment amount based on the sending-end grid frequency and the system frequency reference value when the flexible direct current power adjustment amount exceeds a preset limit range and the system frequency deviation exceeds a preset frequency control dead zone;

[0033] The VSC dynamic adaptive reactive power support control unit is used to provide reactive power support based on the constant direct power adjustment amount and the VSC original reactive power reference value.

[0034] On the other hand, the present application also proposes an AC / DC hybrid synchronous device, which includes: a storage device storing computer-readable instructions; and a processor executing the computer-readable instructions stored in the storage device to realize a dynamic coordination method of flexible DC co-frequency control and normal DC single-side FLC coordinated control and voltage support.

[0035] On the other hand, the present application also proposes a storage medium, which stores computer-readable instructions. The computer-readable instructions are executed by a processor in an AC / DC hybrid synchronous device to implement a dynamic coordination method of flexible DC co-frequency control and normal DC single-side FLC coordinated control and voltage support.

[0036] It can be seen from the above technical solutions that the present application obtains the flexible direct current power regulation amount through the sending-end power grid frequency, the receiving-end power grid frequency and the system frequency reference value; then, when the flexible direct current power regulation amount exceeds the preset limit range and the system frequency deviation exceeds the preset frequency control dead zone, the normal direct current power regulation amount is output based on the sending-end power grid frequency and the system frequency reference value; and then reactive power support is provided based on the normal direct current power regulation amount and the original reactive power reference value of the VSC. By utilizing the flexible direct current same-frequency control, within the range of the flexible direct current power regulation amount, the frequency of the sending-end power grid and the receiving-end power grid can be guaranteed to be consistent and synchronous, and the frequency regulation resources of the sending-end power grid and the receiving-end power grid can be shared in real time and automatically. By utilizing the normal direct current single-side FLC, the frequency stability of the sending-end power grid is improved. And by utilizing the VSC dynamic adaptive reactive power support control, rapid reactive power support is provided for conventional direct current, avoiding frequent operation of the normal direct current converter transformer and filter during the operation of the normal direct current single-side FLC, thereby improving the service life of the direct current equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0039] Figure 1 It is a flow chart of a method for dynamically coordinating flexible direct current co-frequency control and normally direct current single-side FLC coordinated control and voltage support provided in an embodiment of the present application;

[0040] Figure 2 This is a functional module diagram of the AC / DC hybrid synchronous power grid system provided in the embodiment of the present application.

[0041] Figure 3 It is a schematic diagram of the equipment structure of the hardware operating environment involved in the dynamic coordination method of flexible direct current co-frequency control and normal direct current single-side FLC coordinated control and voltage support in the embodiment of the present application. DETAILED DESCRIPTION

[0042] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0043] It should be noted that in this application, "at least one" means one or more, and "more than one" means two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0044] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way. The following embodiments and features in the embodiments may be combined with each other without conflict.

[0045] To facilitate understanding, the technical terms involved in the embodiments of the present application are first introduced below.

[0046] 1. Flexible DC transmission technology: a transmission technology based on voltage source converter (VSC) with high controllability and flexibility.

[0047] The basic principle is to use VSC, self-shutdown devices and PWM (Pulse Width Modulation) technology to achieve high controllability of power transmission. By adjusting the output voltage amplitude and phase angle of the VSC, the transmission of active power and reactive power can be independently controlled.

[0048] VSC is the core component of the flexible DC transmission system, which usually uses IGBT (Insulated Gate Bipolar Transistor) or GTO (Gate-Turn-Off Thyristor) as the turnable device. These devices can switch quickly and achieve high-frequency modulation, thereby accurately controlling current and voltage.

[0049] 2. Flexible direct current frequency control: The frequency synchronization between different grid regions is achieved through flexible direct current transmission technology. This technology allows the current and voltage to be regulated by power electronic devices without direct physical connection, thereby achieving coordinated work between different grid regions.

[0050] 3. FLC: refers to Frequency Limiter Controller.

[0051] FLC is a device used to control and regulate the frequency of the power system, ensuring that the system can remain stable under different operating conditions. By adjusting the transmission of active power and reactive power, FLC can effectively prevent frequency fluctuations and improve the reliability of the power system.

[0052] 4. Normally direct single-side FLC control: In the flexible DC transmission system, the FLC control strategy is configured only at the sending end.

[0053] Normally direct single-side FLC control can effectively control the transmission of active power and reactive power by configuring FLC at the sending end, thereby maintaining the frequency stability of the system.

[0054] 5. VSC dynamic adaptive reactive power support control: By real-time monitoring of the frequency changes of the AC system, the output of reactive current is automatically adjusted to support and stabilize the AC voltage.

[0055] The core idea of ​​this control method is to utilize the high controllability of VSC to dynamically adjust reactive power according to system demand, thereby maintaining the stable operation of the power grid.

[0056] 6. Dead zone: In the field of power system stability and control technology, dead zone usually refers to a fault or protection blind area in a specific area. That is, a fault occurs in an area that cannot be covered by certain equipment or protection devices. These areas are usually formed due to the physical layout of the equipment or the limitations of the protection logic.

[0057] In the typical protection dead zone problem of 220 kV substation, due to the defects of the working principle of the relay protection device itself, when the protected element fails in a certain small range, it may not be removed in time, resulting in a dead zone fault. Although the probability of this fault is small, as the power grid becomes more and more complex, its impact on the stable operation of the system is gradually increasing.

[0058] 7. PI control: Proportional-Integral Control.

[0059] PI control is based on two main links: proportional (P) and integral (I). The proportional link immediately reflects the system deviation and makes adjustments to reduce the error once a deviation occurs, while the integral link is used to eliminate long-term errors and improve the system's error-free degree.

[0060] In power systems, PI control continuously adjusts control variables such as voltage and current to make the actual output of the system close to or equal to the desired value. In power grids, PI control is used to adjust the tap position of transformers and the output of reactive compensation devices to maintain voltage levels and reactive power balance.

[0061] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0062] In large-scale AC / DC hybrid synchronous power grid systems, short-circuit current exceeding the standard, fault propagation, low-frequency oscillation and other problems are prone to occur. Therefore, in order to limit the short-circuit current level, eliminate the possibility of low-frequency oscillation from the network structure, and block the transmission of AC faults in the network structure, DC asynchronous networking is a better choice.

[0063] After large-scale synchronous power grids are interconnected via DC asynchronous interconnection, the rotational inertia and frequency regulation capacity of the original synchronous power grid are split. The rotational inertia and frequency regulation capacity of each subsystem are much smaller than those of the entire system. The frequency stability problem becomes the main stability problem of the asynchronous regional power grid.

[0064] In order to solve the frequency stability problem of asynchronous regional power grids, the embodiment of the present application first obtains the flexible DC power adjustment amount through the sending-end power grid frequency, the receiving-end power grid frequency and the system frequency reference value; then, when the flexible DC power adjustment amount exceeds the preset limit range and the system frequency deviation exceeds the preset frequency control dead zone, the normal DC power adjustment amount is output based on the sending-end power grid frequency and the system frequency reference value; and then reactive power support is provided based on the normal DC power adjustment amount and the original reactive power reference value of the VSC. In this way, the rapid controllability of the DC transmission system is fully utilized, the flexible DC adopts the flexible DC same-frequency control, the conventional DC adopts the single-side FLC control, the system active power shortage is quickly balanced, the grid primary frequency regulation is participated in, and the purpose of effectively improving the system frequency stability is achieved.

[0065] It should be noted that the execution subject of this embodiment may be a computing service device with data processing, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or an electronic device capable of realizing the above functions, an AC / DC hybrid synchronous device, etc. The following takes an AC / DC hybrid synchronous device as an example to illustrate this embodiment and the following embodiments.

[0066] Reference Figure 1 , Figure 1 This is a flow chart of the first embodiment of the method for dynamic coordination of flexible direct current co-frequency control and normally direct current single-side FLC coordinated control and voltage support of the present application.

[0067] In this embodiment, the method for dynamically coordinating flexible direct current co-frequency control with single-side FLC coordinated control and voltage support includes steps S100 to S300:

[0068] Step S100: obtaining a flexible direct current power adjustment amount based on the sending-end grid frequency, the receiving-end grid frequency and a system frequency reference value.

[0069] It should be noted that the sending-end grid frequency refers to the frequency state of the sending-end grid when the electric energy is transmitted from the power generation side (sending end) to the power consumption side (receiving end) through the high-voltage direct current transmission technology in the power system. The receiving-end grid frequency refers to the grid frequency state of the side (receiving end) that receives the electric energy through the high-voltage direct current transmission technology in the power system.

[0070] The system frequency reference value refers to the standard frequency value set by the power system under normal operating conditions. This reference value is the target of power system frequency control and an important indicator for measuring the frequency stability of the power system. In different countries and regions, the system frequency reference value may vary, but it is usually around 50Hz or 60Hz. The setting of the system frequency reference value needs to comprehensively consider multiple factors such as the load characteristics, power generation capacity, and transmission distance of the power system.

[0071] In this embodiment, when obtaining the flexible DC power adjustment amount, the difference between the sending-end grid frequency and the system frequency reference value, as well as the difference between the receiving-end grid frequency and the system frequency reference value can be determined first; then, the flexible DC power adjustment amount is obtained by performing filtering operations, DC isolation operations, PI control operations, and limiting operations on the difference between the sending-end grid frequency and the system frequency reference value and the difference between the receiving-end grid frequency and the system frequency reference value.

[0072] Furthermore, after obtaining the flexible DC power adjustment amount, the flexible DC power adjustment amount and the flexible DC original power reference value are superimposed to obtain a VSC active power instruction; then, based on the VSC active power instruction and the flexible DC power adjustment amount range, the actual operating power of the flexible DC is adjusted.

[0073] In some embodiments of the present application, a method for determining a flexible direct current power adjustment amount range includes:

[0074] Step S110: determining an upper limit of the flexible DC power adjustment range according to the flexible DC power rating, the flexible DC actual operating power and the flexible DC overload capacity coefficient;

[0075] Step S120: determining a lower limit of the flexible DC power adjustment amount range according to the flexible DC power rated value, the flexible DC actual operating power and the flexible DC power minimum operating level coefficient;

[0076] Step S130: Determine the flexible DC power adjustment range based on the upper limit of the flexible DC power adjustment range and the lower limit of the flexible DC power adjustment range.

[0077] In this embodiment, the upper limit ΔP of the flexible direct current power adjustment range max1 The calculation formula can be expressed as, ΔP max1 =k1P N1 – P1. In the formula, P N1 is the rated value of flexible DC power, P1 is the actual operating power of flexible DC, k1 is the overload capacity coefficient of flexible DC. At present, the maximum value of k1 is generally 1.05, but as the capacity of flexible DC converter valve switching devices increases, the maximum value of k1 will continue to increase.

[0078] The lower limit of the flexible DC power regulation range ΔP min1 The calculation formula can be expressed as, ΔP min1 = P1 – m1P N1 In the formula, m1 is the coefficient of the lowest operating level of the flexible DC power. When the flexible DC converter valve adopts a hybrid structure of full-bridge submodule and half-bridge submodule, m1 can be zero.

[0079] When m 1取值 When it is less than zero, the flexible DC power flow reverses, and the value of m1 is determined by the specific working conditions.

[0080] Step S200: When the flexible DC power adjustment amount exceeds a preset limit range and the system frequency deviation exceeds a preset frequency control dead zone, a normal DC power adjustment amount is output based on the sending-end grid frequency and the system frequency reference value.

[0081] In this embodiment, the flexible direct current power regulation amount is used as the output normal direct current power regulation amount, and the starting criterion for the subsequent provision of reactive power support. When the flexible direct current power regulation amount exceeds the limit range, and the system frequency deviation exceeds the preset frequency control dead zone, the step of outputting the normal direct current power regulation amount and the step of providing reactive power support are executed. It should be noted that the preset frequency control dead zone refers to the frequency control dead zone of the normal direct current single-side FLC control unit. Preferably, the range of the preset frequency control dead zone is -0.14Hz to -0.1Hz, and 0.1Hz to 0.14Hz.

[0082] Furthermore, after outputting the normal DC power adjustment amount, the normal DC power adjustment amount is subjected to logical judgment, normalization processing, and PI control to obtain a trigger angle adjustment amount corresponding to the normal DC power adjustment amount; then, the actual operating power of the conventional DC is adjusted according to the trigger angle adjustment amount and the range of the normal DC power adjustment amount.

[0083] Optionally, when obtaining the constant direct power regulation amount, the difference between the sending-end grid frequency and the system frequency reference value is first calculated, and then the difference is passed through control links such as dead zone, PI control, and limiting to obtain the constant direct power regulation amount.

[0084] In some embodiments of the present application, the normal direct power adjustment amount range may be determined by determining an upper limit and a lower limit of the normal direct power adjustment amount range.

[0085] Optionally, the upper limit ΔP of the normal direct power adjustment range max2 The calculation formula can be expressed as, ΔP max2 =k2P N2 –P2. In the formula, P N2 is the rated value of conventional DC power, P2 is the actual operating power of conventional DC, k2 is the overload capacity coefficient of conventional DC. In case of long-term overload, the maximum value of k2 is generally 1.1, and in case of short-term overload, the maximum value of k2 is generally 1.2.

[0086] The lower limit of the normal direct power adjustment range ΔP min2 The calculation formula can be expressed as, ΔP min2 = P2 – m2P N2 Wherein, m2 is the coefficient of the lowest operating level of conventional DC power, and the value of m2 is 0.5.

[0087] Step S300: Providing reactive power support based on the normal direct power adjustment amount and the original reactive power reference value of the VSC.

[0088] In this embodiment, before providing reactive power support, a power factor calculation operation is first performed on the normal DC power adjustment amount to obtain a VSC additional reactive power adjustment amount; then, the VSC additional reactive power adjustment amount and the VSC original reactive power instruction are superimposed to obtain an updated VSC reactive power instruction; and then reactive power support is provided based on the updated VSC reactive power instruction. The reactive power support here includes adjusting the reactive power generated by the flexible DC. Thus, the AC voltage support function of the flexible DC to the conventional DC is realized.

[0089] In some embodiments of the present application, the step of performing a power factor calculation operation on the normal direct power regulation amount to obtain the VSC additional reactive power regulation amount includes:

[0090] Step S310: determining a tangent value of a power factor measured by a conventional DC valve connected to the flexible DC;

[0091] Step S320: performing a product operation on the tangent value and the constant direct power adjustment amount to obtain the VSC additional reactive power adjustment amount.

[0092] Specifically, the calculation formula of VSC additional reactive power regulation can be expressed as: ΔQ = ΔP d2 tanφ. Where φ is the power factor of the conventional DC valve side connected to the flexible DC.

[0093] As an optional implementation, the VSC active power command obtained by superimposing the flexible DC power regulation amount and the flexible DC original power reference value, and the updated VSC reactive power command obtained by superimposing the VSC additional reactive power regulation amount and the VSC original reactive power command, are generated through a dynamic limiting link including PI control to generate the active power command i required for the VSC inner loop control. dref With reactive power instruction i qref .

[0094] As another optional implementation, for the active power command i required for the VSC inner loop control, dref With reactive power instruction i qref , the dynamic limit calculation formula can be expressed as .

[0095] In the technical solution provided in this embodiment, the flexible direct current power regulation amount is obtained through the sending-end power grid frequency, the receiving-end power grid frequency and the system frequency reference value; then, when the flexible direct current power regulation amount exceeds the preset limit range and the system frequency deviation exceeds the preset frequency control dead zone, the normal direct current power regulation amount is output based on the sending-end power grid frequency and the system frequency reference value; and then reactive power support is provided based on the normal direct current power regulation amount and the original reactive power reference value of the VSC. By utilizing the flexible direct current co-frequency control, the frequencies of the sending-end power grid and the receiving-end power grid can be guaranteed to be consistent and synchronous within the flexible direct current power regulation amount range, and the frequency regulation resources of the sending-end power grid and the receiving-end power grid can be shared in real time and automatically. By utilizing the normal direct current single-side FLC, the frequency stability of the sending-end power grid is improved. And by utilizing the VSC dynamic adaptive reactive power support control, the conventional direct current is provided with rapid reactive power support, so as to avoid the frequent operation of the normal direct current converter transformer and filter during the operation of the normal direct current single-side FLC, and improve the service life of the direct current equipment.

[0096] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the dynamic coordination method of the flexible direct current co-frequency control and the normally direct current single-sided FLC coordinated control and voltage support of the present application. More forms of simple transformations based on this technical concept are all within the scope of protection of the present application.

[0097] like Figure 2, is a functional module diagram of an AC / DC hybrid synchronous power grid system 100 provided in an embodiment of the present application. The AC / DC hybrid synchronous power grid system 100 includes a flexible DC co-frequency control unit 110, a normally DC single-side FLC control unit 120, and a VSC dynamic adaptive reactive power support control unit 130. The unit referred to in the present application refers to a series of computer-readable instruction segments that can be acquired by a processor and can perform fixed functions, which are stored in a storage device.

[0098] A flexible direct current frequency control unit is used to obtain a flexible direct current power adjustment amount based on the sending-end grid frequency, the receiving-end grid frequency and the system frequency reference value;

[0099] A single-side FLC control unit for the flexible direct current, used to output a normal direct current power adjustment amount based on the sending-end grid frequency and the system frequency reference value when the flexible direct current power adjustment amount exceeds a preset limit range and the system frequency deviation exceeds a preset frequency control dead zone;

[0100] The VSC dynamic adaptive reactive power support control unit is used to provide reactive power support based on the constant direct power adjustment amount and the VSC original reactive power reference value.

[0101] The AC / DC hybrid synchronous power grid system provided in the present application adopts the dynamic coordination method of flexible DC co-frequency control and normal DC single-side FLC coordinated control and voltage support in the above-mentioned embodiment, which can solve the technical problem of insufficient frequency stability of asynchronous regional power grids.

[0102] Compared with the prior art, the beneficial effects of the AC / DC hybrid synchronous power grid system provided by the present application are that the asynchronous DC sending and receiving power grids are coordinated with the single-side FLC control of the normal DC through the flexible DC co-frequency operation control, so as to realize the real-time automatic sharing of the frequency regulation resources of the asynchronous DC sending and receiving power grids, improve the frequency stability of the sending and receiving power grids, and the VSC dynamic adaptive reactive power support control provides real-time automatic rapid reactive power support for the normal DC, reduce the number of converter transformer taps and filter actions during the active power regulation of the single-side FLC of the normal DC, and improve the reliable DC power supply and equipment service life.

[0103] Other technical features of the AC / DC hybrid synchronous power grid system are the same as those disclosed in the above-mentioned embodiment method and will not be described in detail here.

[0104] It should be noted that the description of the above specific implementation is to facilitate the understanding and application of the present invention by ordinary technicians in this technical field, but the present invention is not limited to the described implementation. The basic idea of ​​the present invention is to provide a dynamic coordination method of flexible direct current co-frequency control and normal direct current single-side FLC coordinated control and voltage support, rather than the power grid system to which the dynamic coordination method is applied. Any power grid system that uses the dynamic coordination method provided by the present invention and the present invention falls within the protection scope of the present invention. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made to the present invention by those skilled in the art based on the disclosure of the present invention should be within the protection scope of the present invention.

[0105] The present application provides an AC / DC hybrid synchronous device, which includes: at least one processor; and a storage device that is communicatively connected to the at least one processor; wherein the storage device stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the dynamic coordination method of flexible DC co-frequency control and normally DC single-side FLC coordinated control and voltage support in the above-mentioned embodiment.

[0106] Reference below Figure 3 , which shows a schematic diagram of the structure of an AC / DC hybrid synchronous device suitable for implementing the embodiment of the present application. The AC / DC hybrid synchronous device in the embodiment of the present application may include but is not limited to mobile terminals such as mobile phones, laptops, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions: tablet computers), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 3 The AC / DC hybrid synchronous device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0107] like Figure 3As shown, the AC / DC hybrid synchronous device may include a processor 1001 (e.g., a central processing unit, a graphics processor, etc.), which may perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the AC / DC hybrid synchronous device are also stored. The processor 1001, ROM1002, and RAM1004 are connected to each other via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems may be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the AC / DC hybrid synchronous device to communicate with other devices wirelessly or by wire to exchange data. Although the figure shows an AC / DC hybrid synchronous device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or have alternatively.

[0108] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processor 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0109] The AC / DC hybrid synchronous device provided by the present application adopts the dynamic coordination method of flexible direct current co-frequency control and normal direct current single-side FLC coordinated control and voltage support in the above-mentioned embodiment, which can solve the technical problem of insufficient frequency stability of asynchronous regional power grid. Compared with the prior art, the beneficial effects of the AC / DC hybrid synchronous device provided by the present application are the same as the beneficial effects of the dynamic coordination method of flexible direct current co-frequency control and normal direct current single-side FLC coordinated control and voltage support provided by the above-mentioned embodiment, and other technical features in the AC / DC hybrid synchronous device are the same as the features disclosed in the previous embodiment method, which will not be repeated here.

[0110] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0111] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0112] The present application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, and the computer-readable program instructions are used to execute the dynamic coordination method of flexible direct current co-frequency control and normally direct current single-side FLC coordinated control and voltage support in the above-mentioned embodiment.

[0113] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM: Random Access Memory), a read-only memory (ROM: Read Only Memory), an erasable programmable read-only memory (EPROM: Erasable Programmable Read Only Memory or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM: CD-Read Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency: Radio Frequency), etc., or any suitable combination of the above.

[0114] The computer-readable storage medium may be included in the AC / DC hybrid synchronous device; or may exist independently without being assembled into the AC / DC hybrid synchronous device.

[0115] The above-mentioned computer-readable storage medium carries one or more programs. When the above-mentioned one or more programs are executed by the AC / DC hybrid synchronous device, the AC / DC hybrid synchronous device: obtains a flexible DC power adjustment amount through the sending-end grid frequency, the receiving-end grid frequency and the system frequency reference value; then, when the flexible DC power adjustment amount exceeds a preset limit range and the system frequency deviation exceeds a preset frequency control dead zone, outputs a normal DC power adjustment amount based on the sending-end grid frequency and the system frequency reference value; and further provides reactive power support based on the normal DC power adjustment amount and the original reactive power reference value of the VSC.

[0116] Computer program code for performing the operations of the present application may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0117] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0118] The modules involved in the embodiments described in this application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0119] The readable storage medium provided in the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned method for dynamically coordinating the flexible direct current co-frequency control with the normally direct current single-side FLC coordinated control and voltage support, and can solve the technical problem of insufficient frequency stability of the asynchronous regional power grid. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in the present application are the same as the beneficial effects of the method for dynamically coordinating the flexible direct current co-frequency control with the normally direct current single-side FLC coordinated control and voltage support provided in the above-mentioned embodiment, and will not be repeated here.

[0120] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A dynamic coordination method for flexible direct current co-frequency control and normal direct current single-side FLC coordinated control and voltage support, characterized in that: The method comprises: Based on the sending-end grid frequency, the receiving-end grid frequency and the system frequency reference value, the flexible direct current power regulation amount is obtained; When the flexible direct current power regulation amount exceeds the preset limit range and the system frequency deviation exceeds the preset frequency control dead zone, outputting the normal direct current power regulation amount based on the sending-end grid frequency and the system frequency reference value; Providing reactive power support based on the normal direct power regulation amount and the original reactive power reference value of the VSC; After the step of outputting the normal direct current power adjustment amount based on the sending-end grid frequency and the system frequency reference value when the flexible direct current power adjustment amount exceeds the preset limit range and the system frequency deviation exceeds the preset frequency control dead zone, the method further includes: Performing logic judgment, per-unit processing, and PI control on the normally direct power adjustment amount to obtain a trigger angle adjustment amount corresponding to the normally direct power adjustment amount; The actual operating power of the conventional direct current is adjusted according to the trigger angle adjustment amount and the normal direct current power adjustment amount range.

2. The method according to claim 1, characterized in that The step of obtaining the flexible direct current power adjustment amount based on the sending-end power grid frequency, the receiving-end power grid frequency and the system frequency reference value comprises: Determine the difference between the power grid frequency at the sending end and the system frequency reference value, and determine the difference between the power grid frequency at the receiving end and the system frequency reference value; The difference between the sending-end power grid frequency and the system frequency reference value and the difference between the receiving-end power grid frequency and the system frequency reference value are respectively subjected to filtering operation, DC isolation operation, PI control operation and amplitude limiting operation to obtain the flexible DC power adjustment amount.

3. The method according to claim 1, characterized in that After the step of obtaining the flexible direct current power adjustment amount based on the sending-end power grid frequency, the receiving-end power grid frequency and the system frequency reference value, the method further includes: The flexible DC power adjustment amount and the flexible DC original power reference value are superimposed to obtain a VSC active power instruction; Based on the VSC active power instruction and the flexible DC power adjustment range, the actual operating power of the flexible DC is adjusted.

4. The method according to claim 3, characterized in that Before the step of adjusting the actual operating power of the flexible direct current based on the VSC active power instruction and the flexible direct current power adjustment amount range, the method further includes: Determine the upper limit of the flexible DC power adjustment range according to the flexible DC power rating, the flexible DC actual operating power and the flexible DC overload capacity coefficient; Determine the lower limit of the flexible DC power adjustment amount range according to the flexible DC power rated value, the flexible DC actual operating power and the flexible DC power minimum operating level coefficient; The flexible direct current power adjustment amount range is determined based on the upper limit of the flexible direct current power adjustment amount range and the lower limit of the flexible direct current power adjustment amount range.

5. The method according to claim 1, characterized in that: The step of providing reactive power support based on the constant direct power adjustment amount and the original reactive power reference value of the VSC includes: Performing a power factor calculation operation on the normal direct power regulation amount to obtain a VSC additional reactive power regulation amount; Superimposing the VSC additional reactive power adjustment amount and the VSC original reactive power instruction to obtain an updated VSC reactive power instruction; Based on the updated VSC reactive power instruction, reactive power support is provided, wherein the reactive power support includes adjusting the reactive power generated by the flexible direct current.

6. The method according to claim 5, characterized in that The step of performing a power factor calculation operation on the normal direct power adjustment amount to obtain the VSC additional reactive power adjustment amount comprises: Determine the tangent value of the power factor measured by a conventional DC valve connected to a flexible DC; A product operation is performed on the tangent value and the constant direct power adjustment amount to obtain the VSC additional reactive power adjustment amount.

7. A system for implementing the method for dynamically coordinating flexible direct current co-frequency control and normally direct current single-side FLC coordinated control and voltage support as claimed in claim 1, characterized in that: The system comprises: A flexible direct current frequency control unit is used to obtain a flexible direct current power adjustment amount based on the sending-end grid frequency, the receiving-end grid frequency and the system frequency reference value; A single-side FLC control unit for the flexible direct current, used to output a normal direct current power adjustment amount based on the sending-end grid frequency and the system frequency reference value when the flexible direct current power adjustment amount exceeds a preset limit range and the system frequency deviation exceeds a preset frequency control dead zone; The VSC dynamic adaptive reactive power support control unit is used to provide reactive power support based on the constant direct power adjustment amount and the VSC original reactive power reference value.

8. An AC / DC hybrid synchronous device, characterized in that: The AC / DC hybrid synchronous device comprises: a storage device storing computer-readable instructions; and a processor, executing the computer-readable instructions stored in the storage device to implement the dynamic coordination method of flexible direct current co-frequency control and normally direct current single-side FLC coordinated control and voltage support as described in any one of claims 1 to 6.

9. A storage medium, characterized in that: The storage medium stores computer-readable instructions, which are executed by a processor in an AC / DC hybrid synchronous device to implement the dynamic coordination method of flexible DC co-frequency control and normally DC single-side FLC coordinated control and voltage support as described in any one of claims 1 to 6.

Images