A method and system for power distribution droop control of a multi-parallel static var generator

Abstract

The application discloses a kind of power distribution droop control method and system of multiple parallel static reactive generator, under the control method of original active power filter, by band-pass filter, the harmonic component of grid voltage is added to the instruction value of current control inner loop of active power filter, to inhibit the phenomenon of harmonic compensation resonance.For nonlinear load, better harmonic compensation effect can be realized and the stability of the whole system is improved.At the same time, the simulation model of active power filter applied to compensate the harmonic of nonlinear load is built, and the correctness, practicability and reliability of the proposed control method and related algorithm are verified.The application has good stability, low implementation cost, simple and efficient implementation structure, wide applicability, can adapt to various complex power grid environment, and has relatively practical engineering application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of power quality and reactive power compensation control, and in particular relates to a power distribution droop control method and system for multiple parallel static VAR generators. Background Art

[0002] Voltage is a key indicator of power quality, and ensuring that user voltage remains close to the rated value is a fundamental task in power system operation and regulation. The operating voltage level of a power system depends on its reactive power balance, and sufficient reactive power is essential for maintaining a stable operating voltage level. The static VAR compensator (SVG) is a recently developed, fast reactive power regulation device that provides continuously variable inductive or capacitive reactive power, thereby achieving stable voltage control within a given range.

[0003] With the growth of renewable energy generation, a single static VAR compensator (SVG) struggles to meet the reactive power compensation requirements of high-power applications. Consequently, multiple SVGs are often operated in parallel to increase reactive power compensation capacity, with a centralized controller or communication lines used to distribute compensation capacity. However, due to factors such as communication latency, intercommunication between multiple parallel SVGs not only reduces system reliability but also degrades dynamic response, compromising stable operation. Furthermore, implementing these control methods requires hardware modifications to the original single SVG, significantly increasing system cost and complexity. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a method and system for controlling the power distribution droop of multiple parallel static VAR generators, which is used to solve the technical problem that the compensation power of each SVG cannot be flexibly distributed proportionally in the application scenario of multiple SVG parallel reactive compensation.

[0005] The present invention adopts the following technical solutions:

[0006] A method for controlling power distribution droop of multiple parallel static VAR generators comprises the following steps:

[0007] The components of the grid voltage in the two-phase stationary coordinate system are , Calculate the grid angular frequency as the input of the phase-locked loop and phase ;

[0008] Use the grid angular frequency obtained and phase and direct axis current reference value and quadrature axis current reference value , to conduct counter The current reference value in the two-phase static coordinate system is obtained by transformation And The current inner loop is inputted

[0009] The power distribution droop coefficient of each static var generator is calculated by using the power distribution ratio ;

[0010] The real-time machine-side current value of each static var generator in the two-phase static coordinate system is obtained , The real-time grid-connected current in the two-phase static coordinate system is obtained The power distribution droop coefficient is substituted into the current loop controller deviation, and the calculation result is used as the current loop PR controller input of each static var generator to control the device output current, so as to realize the power distribution of the parallel static var generator.

[0011] Preferably, the component , of the grid voltage in the two-phase static coordinate system is

[0012] The three-phase line voltage of the grid is sampled and transformed to obtain the component , of the grid voltage in the two-phase static coordinate system .

[0013] Preferably, The component , of the grid voltage in the two-phase static coordinate system is obtained by transformation as follows

[0014]

[0015] Among them, , , is the phase voltage of the grid connection point

[0016] Preferably, the direct-axis current reference value and the quadrature-axis current reference value are

[0017] The direct-axis current reference value is calculated by sampling the DC side voltage, and the quadrature-axis current reference value is set

[0018] Preferably, the power distribution coefficient of each static var generator is calculated as follows

[0019] The SVG with the minimum rated current in the multi-parallel SVG is identified

[0020] determining the upper limit of steady-state error of the multi-parallel active filter;

[0021] setting the upper limit of steady-state error as the droop coefficient of the APF with the minimum rated current;

[0022] calculating the droop coefficient of each SVG in the multi-parallel system according to the rated current of the SVG .

[0023] Preferably, the number n of parallel static var generators and the power distribution ratio are determined, and the output power of the kth static var generator is , and the power distribution ratio is .

[0024] Preferably, the upper limit of steady-state error of the multi-parallel active filter is less than 0.05.

[0025] Preferably, the droop coefficient is calculated as follows:

[0026]

[0027] wherein, is the minimum rated current in the multi-parallel SVG, is the upper limit of steady-state error of the multi-parallel active filter, is the rated current of each SVG.

[0028] Preferably, the current loop controller deviation is calculated as follows:

[0029]

[0030] wherein, is the current reference value, is the actual current value, is the power distribution droop coefficient, is the output current of each SVG port.

[0031] In a second aspect, the embodiments of the present application provide a multi-parallel static var generator power distribution droop control system, comprising:

[0032] a calculation module, which calculates the components of the grid voltage in the two-phase static coordinate system , as the input quantity of the phase-locked loop to calculate the grid angular frequency and the phase ;

[0033] a transformation module, which uses the obtained grid angular frequency and the phase and the direct-axis current reference value and quadrature axis current reference value , to conduct counter Transformation to obtain the current reference value in the two-phase stationary coordinate system and And input current inner loop;

[0034] The coefficient module uses the power distribution ratio to calculate the power distribution droop coefficient of each static VAR generator ;

[0035] Distribution module, obtains the real-time machine-side current value of each static VAR generator in the two-phase static coordinate system , , obtain the real-time grid-connected current in the two-phase stationary coordinate system ; The power distribution droop coefficient Substitute the calculated result into the current loop controller deviation and use it as the input of the current loop PR controller of each static VAR generator to control the output current of the device and realize power distribution of parallel static VAR generators.

[0036] In a third aspect, a computer device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for controlling power distribution droop of multiple parallel static VAR generators when executing the computer program.

[0037] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for controlling power distribution droop of multiple parallel static VAR generators.

[0038] In a fifth aspect, a chip comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for controlling power distribution droop of multiple parallel static VAR generators when executing the computer program.

[0039] In a sixth aspect, an embodiment of the present invention provides an electronic device, comprising a computer program, which, when executed by the electronic device, implements the steps of the above-mentioned method for controlling power distribution droop of multiple parallel static VAR generators.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] A power distribution droop control method for multiple parallel static VAR generators (SVRGs) establishes small-signal dynamic characteristic models for key components in a complex source-load interaction system consisting of grid impedance, nonlinear loads, and SVRGs. Based on the established small-signal dynamic models and their inter-coupling relationships, a parasitic feedback model for the entire system is established. This method conducts detailed theoretical research and analysis on the reactive power compensation and stability of the entire system. By sampling the generator-side current, generator-side current feedback is added to the current command of the traditional inner-loop current control with a certain droop coefficient. This introduces a generator-side current response component into the inner-loop current control of each individual unit. Furthermore, compared to other current sharing methods, the proposed power distribution droop control method specifically improves the flexible current sharing of parallel SVRGs and maintains system stability. The existing implementation steps do not require the addition of new hardware such as sensors to the existing SVRG equipment. Furthermore, the implementation steps are clear and concise, the method is concise and efficient, and the additional computational cost is minimal. Therefore, the present invention has excellent applicability and portability, and has high practical value in practical engineering applications. In addition, a corresponding system simulation model was built, and simulation experiments were carried out on the corresponding multi-parallel SVG reactive compensation scenario and the current sharing method proposed in the present invention, verifying the effectiveness and reliability of the method proposed in the present invention.

[0042] Furthermore, as a typical grid-following converter, SVG needs to use a phase-locked loop and other synchronization links to achieve synchronization with the grid fundamental voltage; The components of the grid voltage in the two-phase stationary coordinate system are obtained by transformation 、 , which can be used as the input of the phase-locked loop to obtain the grid voltage angular frequency and phase, thereby maintaining the DC side voltage stability and achieving reactive power compensation.

[0043] Furthermore, it is necessary to control the SVG output current to maintain the DC side voltage stability and realize the reactive power compensation function of the equipment by controlling the quadrature axis current to 0. The direct axis current reference value is obtained through the DC voltage outer loop. and quadrature axis current reference value As the reference value of the current inner loop, it achieves reactive power compensation at the device access point while maintaining DC side voltage stability.

[0044] Furthermore, the proposed droop coefficient power allocation method uses the sampled single-machine output current , by designing the droop coefficient , introduces a steady-state error to the system output current. The fundamental proportional-resonant controller has infinite gain at the grid frequency, and the output fundamental current in the two-phase static coordinate system is tracked without static error, the power is flexibly distributed among the multiple parallel static var generators, and the harmonic compensation effect is ensured.

[0045] Further, in order to reduce the steady-state error of the output current, maintain the port characteristics of the device and the reactive power compensation effect, the upper limit of the steady-state error of the multiple parallel active filter should be less than 0.05 when setting.

[0046] Further, sampling the machine-side current does not increase the number of sensors in the system. In the conventional static reactive power compensation device, the machine-side current is also sampled for device output current control, and the conventional multiple parallel SVG control method. Therefore, the existing detection value of the system is used to adjust the overall characteristics of the system, so that the application is easy to implement and does not change the hardware structure of the original system.

[0047] It can be understood that the beneficial effects of the above-mentioned second aspect to the sixth aspect can be referred to the related description in the first aspect, which will not be repeated here.

[0048] In summary, the method of the application has good stability, low implementation cost, simple and efficient structure, wide applicability, can adapt to various complex power grid environments, and has practical engineering application value.

[0049] The technical solutions of the application will be further described in detail below with the help of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0051] Figure 1 is a working schematic diagram of the multiple parallel static var generator system of the application;

[0052] Figure 2 is a control block diagram of the specific implementation scheme of the application, wherein (a) is a detailed control block diagram, and (b) is a simplified control block diagram;

[0053] Fig. 3 is a waveform diagram of the effect of the current sharing control of the application in the application of the proposed method for double-SVG parallel reactive power compensation working condition; wherein (a) is a waveform diagram of the SVG output current with a droop coefficient , and (b) is a waveform diagram of the SVG output current with a droop coefficient The waveform of the SVG output current in the two-phase rotating coordinate system, where the red waveform is the direct-axis current and the green waveform is the quadrature-axis current;

[0054] Figure 4 A schematic diagram of a computer device provided in accordance with an embodiment of the present invention;

[0055] Figure 5 The present invention is a block diagram of an electronic device according to an embodiment of the present invention.

[0056] Among them: 60. Computer device; 61. Processor; 62. Memory; 63. Computer program; 600. Electronic device; 610. Processing unit; 620. Storage unit; 6201. Random access memory unit; 6202. Cache memory unit; 6203. Read-only memory unit; 6204. Program / Utility; 6205. Program module; 630. Bus; 640. Display unit; 650. Input / output interface; 660. Network adapter; 700. External device. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0058] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0059] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0060] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0061] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0062] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0063] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0064] This invention provides a power distribution droop control method for multiple parallel static VAR generators. This method, based on the detection of grid current and the output current of each unit, enables the SVG to automatically distribute compensation power. Compared with previous research, this method significantly enhances the flexibility and effectiveness of power distribution to each unit, while increasing the capacity of the SVG at the compensation point and maintaining good dynamic response. The proposed scheme is suitable for multiple parallel SVGs and exhibits low steady-state error and improved reliability.

[0065] The present invention provides a control method for power distribution of multiple parallel static var generators based on the traditional static var compensator control method. Based on the mathematical relationship between the voltage outer loop of the SVG control system, the system grid-connected current, and the output current of a single SVG, a series of theoretical analyses and derivations are carried out to analyze the power distribution problem of the multiple parallel SVG system. Based on the control theory and dynamic model of the existing static var generator, the present invention proposes an output power distribution method. By adding a machine-side current proportional control term to the traditional current inner loop control method of the static var generator, a good power distribution effect is achieved.

[0066] Example 1

[0067] The present invention provides a power distribution droop control method for multiple parallel static VAR generators, comprising the following steps:

[0068] S1, sampling grid three-phase line voltage and conduct Transformation, the components of the grid voltage in the two-phase stationary coordinate system are obtained , ; Use it as the input of the phase-locked loop to calculate the grid angular frequency and phase ;

[0069] The transformation is to convert the sampled three-phase voltage signal , and Converted to the components in the two-phase stationary coordinate system , ; Its conversion equation is:

[0070]

[0071] The grid angular frequency can be calculated using a synchronous rotating coordinate system phase-locked loop and phase The phase-locked loop (PLL) primarily uses the Clark transform to extract the phase difference between the grid voltage and the current PLL output. This phase difference is then closed-loop controlled using a PI controller. This way, when the PLL reaches steady-state, the phase difference between the grid voltage and the PLL output is closed-loop controlled to zero, effectively tracking the grid voltage phase.

[0072] S2, sample the DC side voltage, and input the difference between the actual value of the DC side voltage and the reference value into the PI controller to calculate the direct axis current reference value , set the quadrature axis current reference value ;

[0073] S3, using the results from step S1 、 And the result of step S2 and , to conduct counter Transformation to obtain the current reference value in the two-phase stationary coordinate system and ;

[0074] S4. Determine the number n of parallel static VAR generators and the power distribution ratio. Suppose the output power of the kth static VAR generator is , then the power distribution ratio is , use the power distribution ratio to calculate the power distribution coefficient of each static VAR generator ;

[0075] Power distribution droop coefficient of each single machine The steps to determine are:

[0076] S401, identify the smallest rated current among multiple parallel SVGs ( )

[0077] S402, determine the upper limit of the steady-state error of the multi-parallel active filter ( );

[0078] According to the above analysis, this value is also the steady-state error when the SVG with the minimum rated current is running alone. It is usually set below 0.05.

[0079] S403, setting the upper limit of the steady-state error to the droop coefficient of the APF with the minimum rated current;

[0080] S404, according to the rated current of each SVG in the multi-parallel system ( ) to calculate its droop coefficient (δ j ).

[0081] Droop coefficient (δ j ) is calculated as follows:

[0082]

[0083] S5. Obtain the real-time machine-side current value of each static VAR generator in the two-phase stationary coordinate system , obtain the real-time grid-connected current in the two-phase stationary coordinate system ; The power distribution droop coefficient determined in step S4 Substitute into the current loop controller deviation solution formula In step S4, the calculated result is used as the input of the current loop PR controller of each static var generator to control the output current of the device, thereby achieving the desired parallel static var generator power distribution.

[0084] Those skilled in the art will appreciate that various aspects of the present invention may be implemented as systems, methods, or program products. Accordingly, various aspects of the present invention may be implemented in the following forms: entirely in hardware, entirely in software (including firmware, microcode, etc.), or in a combination of hardware and software, collectively referred to herein as "circuits," "modules," or "platforms."

[0085] Example 2

[0086] The present invention provides a multi-parallel static VAR generator power distribution droop control system, which can be used to implement the above-mentioned multi-parallel static VAR generator power distribution droop control method. Specifically, the multi-parallel static VAR generator power distribution droop control system includes a calculation module, a transformation module, a coefficient module and a distribution module.

[0087] Among them, the calculation module converts the components of the grid voltage in the two-phase stationary coordinate system into , Calculate the grid angular frequency as the input of the phase-locked loop and phase ;

[0088] The conversion module uses the obtained grid angular frequency and phase and direct axis current reference value and quadrature axis current reference value , to conduct counter Transformation to obtain the current reference value in the two-phase stationary coordinate system and And input current inner loop;

[0089] The coefficient module uses the power distribution ratio to calculate the power distribution droop coefficient of each static VAR generator ;

[0090] Distribution module, obtains the real-time machine-side current value of each static VAR generator in the two-phase static coordinate system , , obtain the real-time grid-connected current in the two-phase stationary coordinate system ; The power distribution droop coefficient Substitute the calculated result into the current loop controller deviation and use it as the input of the current loop PR controller of each static VAR generator to control the output current of the device and realize power distribution of parallel static VAR generators.

[0091] Example 3

[0092] The present invention provides a terminal device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to implement corresponding method processes or corresponding functions; the processor described in the embodiment of the present invention can be used for the operation of the power distribution droop control method of multiple parallel static VAR generators, including:

[0093] The components of the grid voltage in the two-phase stationary coordinate system are , Calculate the grid angular frequency as the input of the phase-locked loop and phase ; Use the grid angular frequency obtained and phase and direct axis current reference value and quadrature axis current reference value , to conduct counter Transformation to obtain the current reference value in the two-phase stationary coordinate system and And input the current inner loop; use the power distribution ratio to calculate the power distribution droop coefficient of each static VAR generator ; Get the real-time machine-side current value of each static VAR generator in the two-phase static coordinate system , , obtain the real-time grid-connected current in the two-phase stationary coordinate system ; The power distribution droop coefficient Substitute the calculated result into the current loop controller deviation and use it as the input of the current loop PR controller of each static VAR generator to control the output current of the device and realize power distribution of parallel static VAR generators.

[0094] See alsoFigure 4 In an embodiment, the terminal device is a computer device. The computer device 60 in this embodiment includes a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and capable of running on the processor 61. When the computer program 63 is executed by the processor 61, the method of power distribution droop control of the multi-parallel static reactive generator in the embodiment is implemented. To avoid repetition, details are not described here. Alternatively, when the computer program 63 is executed by the processor 61, the functions of each model / unit in the system of power distribution droop control of the multi-parallel static reactive generator in the embodiment are implemented. To avoid repetition, details are not described here.

[0095] The computer device 60 can be a desktop computer, a notebook, a palm computer, a cloud server, and the like. The computer device 60 can include, but is not limited to, the processor 61 and the memory 62. Those skilled in the art can understand that the computer device 60 can include more or less components, or combine certain components, or include different components, such as an input / output device, a network access device, a bus, and the like. Figure 4 The computer device 60 is only an example and does not constitute a limitation on the computer device 60, and can include more or less components than those shown, or combine certain components, or different components, for example, the computer device can also include an input / output device, a network access device, a bus, and the like.

[0096] The processor 61 can be a central processing unit (CPU), and can also be other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, and the like. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0097] The memory 62 can be an internal storage unit of the computer device 60, such as a hard disk or a memory of the computer device 60. The memory 62 can also be an external storage device of the computer device 60, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, and the like.

[0098] Further, the storage 62 can include both an internal storage unit of the computer device 60 and an external storage device. The storage 62 is used to store computer programs and other programs and data required by the computer device. The storage 62 can also be used to temporarily store data that has been output or will be output.

[0099] Referring to Figure 5 , the terminal device is an electronic device 600 in the form of a general computing device. Components of the electronic device can include, but are not limited to, at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including the storage unit 620 and the processing unit 610), a display unit 640, and the like.

[0100] Among them, the storage unit stores program codes, which can be executed by the processing unit 610, so that the processing unit 610 executes the steps according to various exemplary embodiments of the present application described in the method part of the present specification. For example, the processing unit 610 can execute the steps as shown in Figure 2 .

[0101] The storage unit 620 can include a readable medium in the form of a volatile storage unit, such as a random access memory (RAM) 6201 and / or a cache memory unit 6202, and can further include a read-only memory (ROM) 6203.

[0102] The storage unit 620 can also include a program / utility 6204 having a set of (at least one) program modules 6205, including but not limited to, an operating system, one or more application programs, other program modules, and program data, each of which or a combination of which can include implementation of a network environment.

[0103] The bus 630 can be one or more of several types of bus structures, including a storage unit bus or storage unit controller, a peripheral bus, a graphics acceleration port, a processing unit, or a local bus using any of a variety of bus structures.

[0104] The electronic device 600 can also communicate with one or more external devices 700 (e.g., a keyboard, a pointing device, a Bluetooth device, etc.), one or more devices that enable a user to interact with the electronic device 600, and / or any device that enables the electronic device 600 to communicate with one or more other computing devices (e.g., a router, a modem, etc.). Such communication can occur via an input / output (I / O) interface 650. Furthermore, the electronic device 600 can communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network such as the Internet) via a network adapter 660. The network adapter 660 can communicate with other modules of the electronic device 600 via the bus 630. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in conjunction with the electronic device 600, including but not limited to microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0105] Example 4

[0106] The present invention also provides a storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a terminal device, used to store programs and data. It is understood that the computer-readable storage medium herein may include both the built-in storage medium in the terminal device and, of course, the extended storage medium supported by the terminal device. It may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for being loaded and executed by a processor. These instructions may be one or more computer programs (including program code). It should be noted that more specific examples (a non-exhaustive list) of computer-readable storage media herein include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk-read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0107] Computer-readable storage media also include data signals propagated in baseband or as part of a carrier wave, which carry readable program code. Such propagated data signals can take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable storage medium can also be any readable medium other than a readable storage medium, which can send, propagate, or transmit programs for use by or in conjunction with an instruction execution system, device, or device. The program code contained on the readable storage medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above.

[0108] The program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, and the like, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a stand-alone software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0109] The processor may load and execute one or more instructions stored in a computer-readable storage medium to implement the corresponding steps of the method for controlling power distribution droop of multiple parallel static VAR generators in the above embodiment. The processor may load and execute the following steps:

[0110] The components of the grid voltage in the two-phase stationary coordinate system are , Calculate the grid angular frequency as the input of the phase-locked loop and phase ; Use the grid angular frequency obtained and phase and direct axis current reference value and quadrature axis current reference value , to conduct counter Transformation to obtain the current reference value in the two-phase stationary coordinate system and And input the current inner loop; use the power distribution ratio to calculate the power distribution droop coefficient of each static VAR generator ; Get the real-time machine-side current value of each static VAR generator in the two-phase static coordinate system , , obtain the real-time grid-connected current in the two-phase stationary coordinate system ; The power distribution droop coefficient Substitute the calculated result into the current loop controller deviation and use it as the input of the current loop PR controller of each static VAR generator to control the output current of the device and realize power distribution of parallel static VAR generators.

[0111] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0112] See also Figure 1 The specific application scenarios of the reactive power distribution method for multi-machine parallel static VAR generator are:

[0113] The grid supplies power to the nonlinear load, the static var generator is connected in parallel to the front end of the nonlinear load, and the voltage at the grid connection point is sampled. , grid current The fundamental current reference value is generated by the DC voltage control loop , and set , and then generate the output current of each SVG unit through the current controller , compensate for harmonic current The static VAR generator is input into the grid to compensate for the reactive power generated by the nonlinear load. The proposed droop coefficient power allocation method uses the sampled single machine output current , by designing the droop coefficient , introduces a steady-state error to the system output current. At this time, the output current transfer function of a single machine is:

[0114]

[0115] in, .

[0116] when The fundamental wave proportional resonant controller is used, and its gain at the grid frequency is infinite, so that the output fundamental wave current in the two-phase stationary coordinate system can be tracked without static error. For two different parallel SVGs, the output current proportional relationship is:

[0117]

[0118] Flexible power distribution among multiple parallel static VAR generators is achieved and harmonic compensation effect is guaranteed.

[0119] See also Figure 2 , the control block diagram of the static VAR generator using the current sharing method based on the droop coefficient is:

[0120] Controlled by DC voltage Subtract grid-side current The compensation signal is obtained by multiplying the machine side current by the droop coefficient, and then passing through the current control link , the output voltage of the active power filter is controlled by PWM modulation. The actual output current is sampled This negative feedback is fed into the current command. Analysis of this control block diagram shows that this control method achieves current-sharing control of multiple parallel SVGs without affecting the fundamental gain of the original current loop or adding oscillation paths to other subharmonics, thus ensuring system stability.

[0121] Please refer to Figure 3. The simulation model is a dual-machine static VAR generator parallel compensation condition. The nonlinear load in the simulation is a resistive and inductive load. The reactive power distribution droop coefficient is added at 0.5s, where (a) is the droop coefficient. The waveform of the SVG output current in the two-phase rotating coordinate system, (b) is the droop coefficient The waveform of the SVG output current in the two-phase rotating coordinate system, where the red waveform is the direct axis current and the green waveform is the quadrature axis current. From the simulation results Figure 3 (a) and (b), it can be seen that after adding the droop coefficient, the steady-state output power of the two machines meets = , which proves that the method of the present invention can effectively realize the current sharing control of multiple parallel SVGs, and the system can maintain the reactive power compensation effect to meet the requirements.

[0122] In summary, the present invention provides a power distribution droop control method and system for multiple parallel static VAR generators. Under the original static VAR generator control method, a steady-state error disturbance is introduced to the output current of each machine in the parallel SVG system through the droop coefficient, thereby achieving proportional and flexible distribution of output power. For nonlinear loads, the reactive compensation capacity can be achieved under the premise of realizing reactive power compensation at the grid connection point. At the same time, a simulation model of reactive power compensation of multiple parallel static VAR generators was built, and the proposed control method and related algorithms were simulated and verified, proving the correctness, practicality and reliability of the method. The present invention has good stability, low implementation cost, simple and efficient implementation structure, wide applicability, and can adapt to various complex power grid environments. It has relatively practical engineering application value.

[0123] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0124] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0125] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0126] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical functional division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, and can be electrical, mechanical, or other forms.

[0127] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0128] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0129] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above-mentioned various method embodiments. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0130] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices, and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0131] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0132] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0133] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A power distribution droop control method for multiple parallel static VAR generators, characterized in that: The following steps are involved: The components of the grid voltage in the two-phase stationary coordinate system are , Calculate the grid angular frequency as the input of the phase-locked loop and phase ; Use the grid angular frequency obtained and phase and direct axis current reference value and quadrature axis current reference value , to conduct counter Transformation to obtain the current reference value in the two-phase stationary coordinate system and And input current inner loop; The power distribution droop coefficient of each static VAR generator is obtained by calculating the power distribution ratio ; Obtain the real-time machine-side current value of each static VAR generator in a two-phase stationary coordinate system , , obtain the real-time grid-connected current in the two-phase stationary coordinate system ; The power distribution droop coefficient Substitute the calculated result into the current loop controller deviation and use it as the input of the current loop PR controller of each static VAR generator to control the output current of the device and realize power distribution of parallel static VAR generators.

2. The power distribution droop control method for multiple parallel static VAR generators according to claim 1, characterized in that: Components of the grid voltage in a two-phase stationary coordinate system , Specifically: Sampling the three-phase line voltage of the power grid and conduct Transformation, the components of the grid voltage in the two-phase stationary coordinate system are obtained , .

3. The power distribution droop control method for multiple parallel static VAR generators according to claim 2, characterized in that: The components of the grid voltage in the two-phase stationary coordinate system are obtained by transformation , as follows: in, , , is the phase voltage at the grid connection point.

4. The power distribution droop control method for multiple parallel static VAR generators according to claim 1, characterized in that: Direct axis current reference value and quadrature axis current reference value Specifically: Sample the DC side voltage and calculate the DC axis current reference value , set the quadrature axis current reference value .

5. The power distribution droop control method for multiple parallel static VAR generators according to claim 1, characterized in that: Power distribution coefficient of each static VAR generator The calculation is as follows: Identify the SVG with the smallest rated current among multiple parallel SVGs; Determine the upper limit of the steady-state error of multiple parallel active filters; Set the upper limit of the steady-state error to the droop coefficient of the APF with the minimum rated current; Calculate the droop coefficient of each SVG in the multi-parallel system based on its rated current .

6. The power distribution droop control method for multiple parallel static VAR generators according to claim 5, characterized in that: Determine the number n of parallel static VAR generators and the power distribution ratio. Suppose the output power of the kth static VAR generator is , the power distribution ratio is .

7. The power distribution droop control method for multiple parallel static VAR generators according to claim 5, characterized in that: The upper limit of the steady-state error of the multi-parallel active filter is less than 0.

05.

8. The power distribution droop control method for multiple parallel static VAR generators according to claim 5, characterized in that: Droop coefficient The calculation is as follows: in, is the minimum rated current of multiple parallel SVGs, is the upper limit of the steady-state error of the multi-parallel active filter, is the rated current of each SVG.

9. The power distribution droop control method for multiple parallel static VAR generators according to claim 1, characterized in that: Current loop controller deviation The calculation is as follows: in, is the current reference value, is the actual current value, is the power allocation droop coefficient, Output current for each SVG port.

10. A power distribution droop control system for multiple parallel static VAR generators, characterized in that: include: The calculation module converts the components of the grid voltage in the two-phase stationary coordinate system into , Calculate the grid angular frequency as the input of the phase-locked loop and phase ; The conversion module uses the obtained grid angular frequency and phase and direct axis current reference value and quadrature axis current reference value , to conduct counter Transformation to obtain the current reference value in the two-phase stationary coordinate system and ; The coefficient module uses the power distribution ratio to calculate the power distribution droop coefficient of each static VAR generator ; Distribution module, obtains the real-time machine-side current value of each static VAR generator in the two-phase static coordinate system , , obtain the real-time grid-connected current in the two-phase stationary coordinate system ; The power distribution droop coefficient Substitute the calculated result into the current loop controller deviation and use it as the input of the current loop PR controller of each static VAR generator to control the output current of the device and realize power distribution of parallel static VAR generators.

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