A power distribution network harmonic voltage distribution iterative calculation method and system

Abstract

The application discloses a power distribution network harmonic voltage distribution iterative calculation method and system, and is suitable for a power distribution network with multiple power electronic devices incorporated, considers converter characteristics and adopts iterative calculation, and can more accurately calculate power distribution network harmonic voltage distribution by introducing a harmonic impedance model of the converter, improves calculation accuracy, and is especially suitable for modern power distribution networks with increasing converter access; the method can effectively make up for the deficiency of traditional methods in processing power electronic device characteristics, and has high accuracy and practicality.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power quality and harmonic flow calculation, and particularly relates to a distribution network harmonic voltage distribution iterative calculation method and system. BACKGROUND

[0002] In recent years, with the development of renewable energy systems and the large-scale grid connection of power electronic devices, unlike traditional linear loads, power electronic devices will have complex responses such as frequency coupling under harmonic voltage disturbance. The traditional harmonic flow calculation only considers the influence of linear loads, and as the degree of power electronicization of the distribution network increases, the deviation of the traditional calculation increases. Therefore, the characteristics of power electronic devices need to be considered in the harmonic flow calculation to improve the accuracy of the harmonic calculation.

[0003] The traditional harmonic voltage calculation ignores the disturbed response of the converter, equivalent to a constant power source, and ignores the interaction inside the power electronic device, resulting in poor calculation accuracy. SUMMARY

[0004] The technical problem to be solved by the application is to provide a distribution network harmonic voltage distribution iterative calculation method and system, which considers the characteristics of the converter and combines the two by iterative calculation, to solve the technical problem of the deficiency of the traditional calculation method in dealing with the converter, and has high accuracy and practicality.

[0005] The application adopts the following technical solutions:

[0006] A distribution network harmonic voltage distribution iterative calculation method, comprising the following steps:

[0007] S1, obtaining the load size of each node of the distribution network, the line impedance between the nodes, determining the access capacity and position of the power electronic converter and the harmonic source;

[0008] S2, obtaining the filter parameters and control method of the power electronic converter in step S1, and determining the harmonic emission characteristics of the harmonic source in step S1 ;

[0009] S3, according to the node load condition and line parameter obtained in step S1, calculating the fundamental wave flow of the distribution network;

[0010] S4, according to the flow calculation result of step S3, equivalent to a resistance-inductance series load for the load on the distribution network node except the converter, and calculating the equivalent parameters;

[0011] S5, according to the line parameter obtained in step S1 and the equivalent load obtained in step S4, calculating the harmonic impedance matrix of the network frame ;

[0012] S6, obtaining the harmonic impedance characteristics of the power electronic converter model according to the filter parameters and the controller parameters of the power electronic converter in step S2;

[0013] S7, taking the harmonic emission characteristics of the harmonic source in step S2 as initial harmonic disturbance, and combining the harmonic impedance matrix in step S4, to obtain the initial distribution of the harmonic voltage of the power distribution network;

[0014] S8, according to the harmonic voltage distribution in step S7 and the harmonic impedance characteristics of the power electronic converter in step S6, to obtain the new harmonic current disturbance of the power distribution network;

[0015] S9, superimposing the harmonic current disturbance value in step S8 on the initial harmonic disturbance, and combining the network harmonic impedance matrix in step S5, to obtain the new harmonic voltage distribution;

[0016] S10, according to the harmonic voltage distribution of step S9, repeating steps S7-S8 twice until the harmonic voltage converges, and completing the iterative calculation of the harmonic voltage distribution of the power distribution network.

[0017] Preferably, in step S4, the equivalent parameters are calculated as follows:

[0018]

[0019] wherein, R is the equivalent resistance, X is the equivalent reactance, P is the active power of the node, Q is the reactive power of the node, U is the effective value of the voltage of the node.

[0020] Preferably, in step S5, the network harmonic impedance matrix is calculated under each harmonic respectively, and the specific calculation process is as follows:

[0021] According to the calculated harmonic frequency, the line impedance and the equivalent impedance of the load are calculated, the node admittance matrix of the network is written, and the final harmonic impedance matrix is obtained by inverting the node admittance matrix.

[0022] Preferably, in step S6, the power electronic converter model includes harmonic state space and impedance modeling method.

[0023] Preferably, the harmonic impedance characteristics of the power electronic converter are:

[0024]

[0025] wherein, is the harmonic disturbance voltage, is the harmonic impedance value of the converter.

[0026] Preferably, in step S7, the initial distribution of the harmonic voltage of the power distribution network is:

[0027]

[0028] wherein, is the harmonic impedance matrix of the network, is the harmonic emission characteristic of the harmonic source.

[0029] Preferably, in step S8, the new harmonic current disturbance of the power distribution network is:

[0030]

[0031] wherein, is the initial distribution of the harmonic voltage of the power distribution network, is the harmonic impedance value of the converter.

[0032] Preferably, steps S7-S9 are repeated iteratively to obtain a more accurate power distribution network harmonic voltage distribution result considering the characteristics of the converter through harmonic voltage distribution and harmonic current calculation.

[0033] Preferably, in step S9, the new harmonic voltage distribution is:

[0034]

[0035] wherein, is the harmonic impedance matrix of the network, is the harmonic emission characteristic of the harmonic source, is the new harmonic current disturbance of the power distribution network.

[0036] In a second aspect, an embodiment of the present application provides a power distribution network harmonic voltage distribution iterative calculation system, comprising:

[0037] a parameter module, which acquires the load size of each node of the power distribution network, the line impedance between nodes, determines the access capacity and position of the power electronic converter and the harmonic source, acquires the filter parameters of the power electronic converter and its control method, and determines the harmonic emission characteristic of the harmonic source ; according to the node load condition and the line parameter, the fundamental power flow of the power distribution network is calculated;

[0038] a calculation module, which, according to the power flow calculation result, equivalent the load on the nodes of the power distribution network except the converter to a resistance-inductance series load, and calculates the equivalent parameters; according to the line parameter and the equivalent load, the harmonic impedance matrix of the network is calculated ;

[0039] The disturbance module obtains the harmonic impedance characteristics of the power electronic converter model according to the filter parameters and the controller parameters of the power electronic converter, and calculates the initial distribution of the harmonic voltage of the power distribution network by combining the harmonic impedance matrix and the harmonic emission characteristics of the harmonic source as the initial harmonic disturbance.

[0040] The voltage module calculates the new harmonic current disturbance of the power distribution network according to the harmonic voltage distribution and the harmonic impedance characteristics of the power electronic converter, and superimposes the harmonic current disturbance value on the initial harmonic disturbance to calculate the new harmonic voltage distribution by combining the network impedance matrix.

[0041] The output module repeats the calculation according to the new harmonic voltage distribution until the harmonic voltage converges, and completes the iterative calculation of the harmonic voltage distribution of the power distribution network.

[0042] In a third aspect, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the above power distribution network harmonic voltage distribution iterative calculation method when executing the computer program.

[0043] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium including a computer program, and the computer program implements the steps of the above power distribution network harmonic voltage distribution iterative calculation method when executed by a processor.

[0044] In a fifth aspect, a chip includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the above power distribution network harmonic voltage distribution iterative calculation method when executing the computer program.

[0045] In a sixth aspect, an embodiment of the present application provides an electronic device including a computer program, and the computer program implements the steps of the above power distribution network harmonic voltage distribution iterative calculation method when executed by the electronic device.

[0046] Compared with the prior art, the present application has at least the following beneficial effects:

[0047] A power distribution network harmonic voltage distribution iterative calculation method, for a new type of power distribution network system with multiple power electronic devices, considers the characteristics of the converter on the basis of the traditional harmonic calculation method. By introducing the impedance model of the converter, the output current characteristics of the converter under harmonic voltage disturbance are calculated, and the harmonic voltage distribution of the power distribution network is more accurately calculated; the harmonic state space or impedance model is used to describe the harmonic current emission of the converter under voltage disturbance; the converter model and the node impedance matrix are connected in an iterative manner, and the harmonic voltage distribution of the power distribution network is finally calculated.

[0048] Further, the general load is modeled by using the linear element equivalent method. This method is close to the characteristics of the linear load, and does not increase the complexity of the network impedance equation.

[0049] Further, the network impedance equation of the system cannot be directly solved, and is generally obtained by inverting the node admittance equation of the system. The node admittance equation of the system can be directly listed according to the structure and impedance parameters of the system. The network impedance equations of the system at different frequencies are independent of each other and need to be calculated respectively.

[0050] Further, the present application relates to a method for calculating harmonic voltage distribution, and therefore a method for modeling the converter needs to be used, which can reflect the harmonic impedance characteristics of the converter. The harmonic state space and impedance modeling can both accurately describe the harmonic impedance characteristics of the converter.

[0051] Further, considering that the converter model and the system network impedance equation are obtained in different coordinate systems and number fields respectively, and cannot be directly solved together, but the calculation results of the two can be equivalently converted. Therefore, an iterative method is used: first, the network harmonic voltage distribution is calculated, and then the harmonic emission of the converter is calculated using the calculation result. Finally, the harmonic voltage distribution is updated according to the harmonic emission of the converter. The iteration is repeated until convergence is reached. The iterative method realizes the interaction between the two models and finally calculates the steady-state result.

[0052] 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.

[0053] In summary, the present application can more accurately calculate the harmonic voltage distribution of the power distribution network, improve the calculation accuracy, and is especially suitable for modern power distribution networks with increasing number of converters.

[0054] The technical solutions of the present application will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The iteration flowchart of the method of the present application;

[0056] Figure 2 The verification scene diagram of the method of the present application;

[0057] Fig. 3 is a comparison result diagram of the method of the present application and the traditional method, wherein (a) is the iteration result (amplitude) of the 7th harmonic voltage of the node, (b) is the iteration result (phase) of the 7th harmonic voltage of the node, (c) is the iteration result (amplitude) of the 11th harmonic voltage of the node, and (d) is the iteration result (phase) of the 11th harmonic voltage of the node;

[0058] Figure 4 A schematic diagram of a computer device according to an embodiment of the present application is provided.

[0059] Figure 5 A block diagram of a chip according to an embodiment of the present application is provided. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of the present application.

[0061] In the description of the present application, it should be understood that the terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or sets thereof.

[0062] It should also be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and the appended claims of the present application, unless otherwise clearly indicated by the context, the singular forms "a", "an" and "the" are intended to include the plural forms as well.

[0063] It should be further understood that the term "and / or" used in the specification and the appended claims of the present application means any combination of one or more of the associated listed items and all possible combinations thereof, and includes these combinations, for example, A and / or B can represent three cases of A alone, A and B together, and B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0064] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present application to describe the preset ranges, etc., these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from each other. For example, the first preset range can also be referred to as the second preset range, and similarly, the second preset range can also be referred to as the first preset range without departing from the scope of the embodiments of the present application.

[0065] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "while" or "in response to determining" or "in response to detecting." Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" can be interpreted to mean "when it is determined" or "in response to determining" or "when [a stated condition or event] is detected" or "in response to detecting [a stated condition or event]."

[0066] The various structural diagrams according to the disclosed embodiments of the present application are shown in the drawings. These diagrams are not drawn to scale, in which certain details are exaggerated for clarity of presentation and may be omitted, the shapes and relative sizes and positions of the various regions, layers, and elements shown in the drawings are only exemplary and may deviate in actual devices due to manufacturing tolerances or technical limitations, and a person skilled in the art can additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0067] Under the traditional power distribution network, there are fewer power electronic devices, and the characteristics of the converter are not obvious. Nowadays, more and more converters are connected to the power distribution network, and the original characteristics of the power distribution network have changed significantly. The converter has strong frequency coupling and interaction characteristics, which enhances the interaction between the nodes of the power distribution network. The existing harmonic voltage distribution calculation method ignores the consideration of the characteristics of the power electronic device, resulting in poor calculation accuracy, which cannot meet the calculation demand of the new power distribution network. The calculation method proposed in the present application introduces the description of the characteristics of the converter compared with the original method, which improves the calculation accuracy of the harmonic voltage distribution of the power distribution network.

[0068] The present application provides a kind of power distribution network harmonic voltage distribution iterative calculation method, using the idea of iterative calculation improves the calculation accuracy of the harmonic voltage distribution of the power distribution network of multiple power electronic devices incorporation;On the basis of traditional harmonic calculation, the harmonic disturbed emission characteristics of the converter are introduced, and the harmonic voltage distribution of the power distribution network is more comprehensively described.

[0069] Please refer to Figure 1 The present application provides a kind of power distribution network harmonic voltage distribution iterative calculation method, including the following steps:

[0070] S1, the load size of each node of the power distribution network, the line impedance between nodes, determine the access capacity and position of power electronic converter and harmonic source;

[0071] S2, the filter parameters of the power electronic converter in step S1 and its control method are obtained, and the harmonic emission characteristics of the harmonic source in S1 are obtained ;

[0072] According to the characteristics of the harmonic source, a constant current source model can be used for fitting.

[0073] S3, according to the node load condition and line parameters obtained in step S1, the fundamental wave power flow of the distribution network is calculated;

[0074] The fundamental wave power flow calculation method of the distribution network is relatively mature, and generally adopts the Newton iteration method.

[0075] S4, according to the power flow calculation result of step S3, the load of the nodes of the distribution network except the converter is equivalent to a resistance-inductance series load, and the equivalent parameters are calculated;

[0076] The equivalent impedance calculation method is to calculate the equivalent impedance according to the power and voltage of the node, and the specific expression is as follows:

[0077]

[0078] Among them, R is the equivalent resistance, X is the equivalent reactance, P is the active power of the node, Q is the reactive power of the node, U is the effective value of the voltage of the node, which is obtained by the power flow calculation in step S3.

[0079] S5, according to the line parameters obtained in step S1 and the equivalent load obtained in step S4, the harmonic impedance matrix of the network frame is calculated ;

[0080] The harmonic impedance matrix of the network frame is calculated under each harmonic to obtain the corresponding impedance matrix, and the specific calculation process is as follows:

[0081] First, the line impedance and the equivalent impedance of the load are calculated according to the calculated harmonic frequency;

[0082] Second, the node admittance matrix of the network frame is listed;

[0083] Then, the node admittance matrix is operated to obtain the final harmonic impedance matrix.

[0084] S6, according to the filter parameters and controller parameters of the power electronic converter in step S2, the harmonic impedance characteristics of the power electronic converter model are obtained ;

[0085] The power electronic converter model includes harmonic state space and impedance modeling method.

[0086] S7, the harmonic emission characteristics of the harmonic source in step S2 are taken as the initial harmonic disturbance, combined with the harmonic impedance matrix in step S4, the initial distribution of the harmonic voltage of the distribution network is calculated, ;

[0087] S8, calculate the new harmonic current disturbance of the power distribution network according to the harmonic voltage distribution in step S7 and the harmonic impedance characteristics of the power electronic converter in step S6 ;

[0088] S9, superimpose the harmonic current disturbance value in step S8 on the initial harmonic disturbance, and calculate the new harmonic voltage distribution in combination with the network impedance matrix in step S5 ;

[0089] Steps S7-S9 can obtain more accurate power distribution network harmonic voltage distribution results considering the characteristics of the converter through repeated iteration of harmonic voltage distribution and harmonic current calculation.

[0090] S10, repeat steps S7-S8 according to the harmonic voltage distribution of step S9 until the harmonic voltage converges.

[0091] Those skilled in the art can understand that various aspects of the present application can be implemented as a system, a method or a program product. Therefore, various aspects of the present application can be implemented in the form of a complete hardware implementation, a complete software implementation (including firmware, microcode, etc.), or a combination of hardware and software aspects, which can be collectively referred to as "circuitry", "module" or "platform" here.

[0092] In another embodiment of the present application, a power distribution network harmonic voltage distribution iterative calculation system is provided, which can be used to implement the above-mentioned power distribution network harmonic voltage distribution iterative calculation method. Specifically, the power distribution network harmonic voltage distribution iterative calculation system comprises a parameter module, a calculation module, a disturbance module, a voltage module and an output module.

[0093] The parameter module obtains the load size of each node of the power distribution network, the line impedance between nodes, determines the access capacity and position of the power electronic converter and the harmonic source, obtains the filter parameters and control method of the power electronic converter, and determines the harmonic emission characteristics of the harmonic source ; according to the node load condition and the line parameter, the fundamental wave flow of the power distribution network is calculated;

[0094] The calculation module, according to the results of the flow calculation, equivalent to the load on the nodes of the distribution network except the converter as a resistance inductance series load, and calculates the equivalent parameters; according to the line parameters and the equivalent load, the harmonic impedance matrix of the network is calculated ;

[0095] The disturbance module obtains the harmonic impedance characteristics of the power electronic converter model according to the filter parameters and the controller parameters of the power electronic converter; the harmonic emission characteristics of the harmonic source are taken as the initial harmonic disturbance, and the harmonic impedance matrix is combined to calculate the initial distribution of the harmonic voltage of the power distribution network;

[0096] The voltage module calculates a new harmonic current disturbance of the power distribution network according to the harmonic voltage distribution and the harmonic impedance characteristics of the power electronic converter; the harmonic current disturbance value is superimposed on the initial harmonic disturbance, and the new harmonic voltage distribution is calculated in combination with the network harmonic impedance matrix;

[0097] The output module repeats the calculation until the harmonic voltage converges, and completes the iteration calculation of the harmonic voltage distribution of the power distribution network according to the new harmonic voltage distribution.

[0098] In another embodiment of the present application, a terminal device is provided, which comprises a processor and a memory, the memory is used to store a computer program, the computer program comprises program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor 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, etc., which are the computing core and control core of the terminal, and are suitable for implementing one or more instructions, and are specifically suitable for loading and executing one or more instructions to implement a corresponding method flow or a corresponding function; the processor in the embodiment of the present application can be used for the operation of the power distribution network harmonic voltage distribution iteration calculation method, which comprises:

[0099] The load size of each node of the power distribution network, the line impedance between nodes, the access capacity and position of the power electronic converter and the harmonic source are obtained, the filter parameters of the power electronic converter and the control method thereof are obtained, and the harmonic emission characteristics of the harmonic source are determined The fundamental wave flow of the power distribution network is calculated according to the obtained node load condition and line parameter; the load except the converter on the power grid node is equivalent to a resistance-inductance series load according to the flow calculation result, and the equivalent parameter is calculated; the harmonic impedance matrix of the network is calculated according to the obtained line parameter and equivalent load ; obtaining harmonic impedance characteristics of the power electronic converter model according to filter parameters and controller parameters of the power electronic converter; taking harmonic emission characteristics of the harmonic source as initial harmonic disturbance, combining the harmonic impedance matrix, and calculating initial distribution of harmonic voltage of the power distribution network; according to the harmonic voltage distribution and the harmonic impedance characteristics of the power electronic converter, calculating new harmonic current disturbance of the power distribution network; superimposing the harmonic current disturbance value on the initial harmonic disturbance, combining the grid harmonic impedance matrix, and calculating new harmonic voltage distribution; according to the new harmonic voltage distribution, repeating until the harmonic voltage converges, and completing the iterative calculation of the harmonic voltage distribution of the power distribution network.

[0100] Please refer to Figure 4 The terminal device is a computer device, and the computer device 60 of the embodiment includes a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61. The computer program 63 implements the method for iterative calculation of the harmonic voltage distribution of the power distribution network in the embodiment when executed by the processor 61. To avoid repetition, details are not described here. Alternatively, the computer program 63 implements the functions of each model / unit in the system for iterative calculation of the harmonic voltage distribution of the power distribution network in the embodiment when executed by the processor 61. To avoid repetition, details are not described here.

[0101] The computer device 60 can be a desktop computer, a notebook computer, 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 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 fewer components than 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.

[0102] 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.

[0103] 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.

[0104] Further, the memory 62 can include both an internal storage unit and an external storage device of the computer device 60. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 can also be used to temporarily store data that has been output or will be output.

[0105] Referring to Figure 5 , the terminal device is a chip, and the chip 600 of the embodiment includes one or more processors 622 and a memory 632 for storing computer programs executable by the processor 622. The computer programs stored in the memory 632 can include one or more than one module each corresponding to a set of instructions. In addition, the processor 622 can be configured to execute the computer programs to perform the power distribution network harmonic voltage distribution iterative calculation method described above.

[0106] In addition, the chip 600 can further include a power supply component 626 configured to perform power management of the chip 600 and a communication component 650 configured to implement communication of the chip 600, such as wired or wireless communication. In addition, the chip 600 can further include an input / output interface 658. The chip 600 can operate based on an operating system stored in the memory 632.

[0107] In another embodiment of the present application, the present application also provides a storage medium, specifically a computer readable storage medium, which is a memory device in a terminal device and is used to store programs and data. It can be understood that the computer readable storage medium herein can include a built-in storage medium in the terminal device, and of course can also include an expansion storage medium supported by the terminal device. The computer readable storage medium provides a storage space, and the storage space stores an operating system of the terminal. In addition, one or more than one instruction suitable for being loaded and executed by a processor is also stored in the storage space, and the instruction can be one or more than one computer program. It should be noted that the computer readable storage medium herein can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory.

[0108] The one or more instructions stored in the computer readable storage medium can be loaded and executed by the processor to implement the corresponding steps of the power distribution network harmonic voltage distribution iterative calculation method in the above embodiments; the one or more instructions stored in the computer readable storage medium are loaded and executed by the processor to implement the following steps:

[0109] Obtaining the load size of each node of the power distribution network, the line impedance between nodes, determining the access capacity and position of the power electronic converter and the harmonic source; obtaining the filter parameters of the power electronic converter and its control method, determining the harmonic emission characteristics of the harmonic source ; calculating the fundamental wave flow of the power distribution network according to the obtained node load condition and line parameter; according to the flow calculation result, the load except the converter on the power grid node is equivalent to a resistance inductance series load, and the equivalent parameter is calculated; according to the obtained line parameter and equivalent load, the harmonic impedance matrix of the network frame is calculated ; obtaining the harmonic impedance characteristics of the power electronic converter model according to the filter parameters and controller parameters of the power electronic converter; taking the harmonic emission characteristics of the harmonic source as the initial harmonic disturbance, combining the harmonic impedance matrix, and calculating the initial distribution of the harmonic voltage of the power distribution network; according to the harmonic voltage distribution and the harmonic impedance characteristics of the power electronic converter, the new harmonic current disturbance of the power distribution network is calculated; superimposing the harmonic current disturbance value on the initial harmonic disturbance, combining the network frame harmonic impedance matrix, and calculating the new harmonic voltage distribution; according to the new harmonic voltage distribution, repeating until the harmonic voltage converges, and completing the harmonic voltage distribution iterative calculation of the power distribution network.

[0110] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application 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 application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0111] Please refer to Figure 1 , the iterative process of the algorithm is:

[0112] Firstly, the fundamental wave current is calculated, and the harmonic impedance matrix of the network is calculated according to the network information. Secondly, the harmonic current characteristics of the harmonic source in the distribution network are taken as the harmonic current disturbance, and the harmonic voltage distribution of the distribution network is calculated according to the harmonic impedance matrix of the network. Then, according to the distribution of the harmonic voltage, the harmonic current emission of the converter is calculated according to the model of the converter (taking the fundamental wave current result as the steady-state operating point of the converter). The harmonic current emission of the converter is superimposed on the harmonic source characteristics to form new harmonic disturbance characteristics, and iterative calculation is performed.

[0113] Please refer to Figure 2 , the verification scene of the algorithm: the scene contains three nodes, and each node is connected to a 40kW converter device.

[0114] Among them, the harmonic current source and the linear load (20kW) are connected in node 1. The specific parameters of the line impedance are shown in the table:

[0115]

[0116] In the simulation verification, two working conditions are included, which are:

[0117] 1) The harmonic current source injects 7th harmonic 100A into the power grid;

[0118] 2) The harmonic current source injects 11th harmonic 50A into the power grid.

[0119] Please refer to Fig. 3, the comparison results of the algorithm proposed in the application and the traditional algorithm and the simulation results. Fig. 3(a) and (b) are the harmonic voltage distribution of each node of the distribution network under the 7th harmonic current disturbance and the comparison, wherein Fig. 3(a) and Fig. 3(b) reflect the iterative calculation process of the harmonic voltage amplitude and phase, Table 1 calculates the accuracy of the proposed method and the simulation result, and Table 2 compares the results of the traditional calculation method and the simulation result.

[0120] Table 1 Comparison of the proposed method and the simulation result

[0121]

[0122] Table 2 Comparison of the traditional method and the simulation result

[0123]

[0124] Fig. 3(c) and (d) are the harmonic voltage distribution of each node of the distribution network under the 11th harmonic current disturbance and the comparison, wherein Fig. 3(c) and Fig. 3(d) reflect the iterative calculation process of the harmonic voltage amplitude and phase, Table 3 calculates the accuracy of the proposed method and the simulation result, and Table 4 compares the results of the traditional calculation method and the simulation result.

[0125] Table 3 Comparison of the method and simulation results of the application

[0126]

[0127] Table 4 Comparison of the traditional method and simulation results

[0128]

[0129] According to the comparison results, the scheme of the application improves the calculation accuracy of the harmonic voltage distribution of the power distribution network by introducing the description of the characteristics of the converter, and the calculation error is less than 5%, which is much higher than the accuracy of the traditional calculation.

[0130] In summary, the iterative calculation method and system for harmonic voltage distribution of the power distribution network consider the characteristics of the converter on the basis of the traditional harmonic calculation method. By introducing the impedance model of the converter, the output current characteristics of the converter under harmonic voltage disturbance are calculated, and the harmonic voltage distribution of the power distribution network is calculated more accurately. The converter has strong frequency coupling and interaction characteristics, which enhances the interaction between nodes of the power distribution network. The existing harmonic voltage distribution calculation method ignores the consideration of the characteristics of power electronic equipment, resulting in poor calculation accuracy and failing to meet the calculation requirements of the new power distribution network. Compared with the original method, the introduction of the description of the characteristics of the converter improves the calculation accuracy of the harmonic voltage distribution of the power distribution network.

[0131] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of software functional unit. In addition, the specific name of each functional unit and module is only for convenient distinction, and does not limit the protection scope of the application. The specific working process of the units and modules in the system can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0132] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in a certain embodiment can be referred to the related description of other embodiments.

[0133] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed in the present application can be realized in electronic hardware or in combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0134] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / terminal and method can be implemented in other ways. For example, the apparatus / terminal embodiments described above are merely schematic. The division of the modules or units is merely a logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed coupling or direct coupling or communication connection between the units can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or in other forms.

[0135] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0136] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0137] The integrated module / unit, if realized in the form of a software function unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of each method embodiment when executed by a processor. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate forms, etc. The computer-readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the computer-readable medium can include or exclude contents according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0138] The present application is described with reference to flowcharts and / or block diagrams of methods, devices, and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams 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 produce a device that implements the flowcharts and / or block diagrams. Figure 1 The flow or multiple flows and / or blocks Figure 1 The device that implements the functions specified in one or more flows or blocks.

[0139] These computer program instructions can also be stored in a computer-readable memory that can guide the computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including instruction devices that implement the flowcharts and / or block diagrams. Figure 1 The flow or multiple flows and / or blocks Figure 1 The device that implements the functions specified in one or more flows or blocks.

[0140] These computer program instructions can also be loaded into a computer or other programmable data processing devices, so that a series of operational steps are performed on the computer or other programmable data processing devices to generate a computer implemented process, so that the instructions executed on the computer or other programmable data processing devices provide a process for implementing the functions specified in the flowchart Figure 1 one flow or multiple flows and / or the functions specified in the block Figure 1 one flow or multiple flows and / or the functions specified in the block

[0141] The above is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A method for iterative calculation of harmonic voltage distribution in a distribution network, characterized in that: The following steps are involved: S1. Obtain the load size of each node in the distribution network and the line impedance between nodes, and determine the access capacity and location of the power electronic converter and harmonic source; S2. Obtain the filter parameters and control method of the power electronic converter in step S1, and determine the harmonic emission characteristics of the harmonic source in step S1. ; S3. Calculate the fundamental power flow of the distribution network based on the node load conditions and line parameters obtained in step S1; S4. Based on the power flow calculation results of step S3, the loads on the distribution network node other than the converter are equivalent to resistance and inductance series loads, and the equivalent parameters are calculated; S5. Calculate the grid harmonic impedance matrix based on the line parameters obtained in step S1 and the equivalent load obtained in step S4. ; S6. Obtaining harmonic impedance characteristics of the power electronic converter model according to the filter parameters and controller parameters of the power electronic converter in step S2; S7. Using the harmonic emission characteristics of the harmonic source in step S2 as the initial harmonic disturbance, combined with the harmonic impedance matrix in step S4, calculate the initial distribution of the harmonic voltage of the distribution network; S8. Calculate a new harmonic current disturbance of the distribution network based on the harmonic voltage distribution in step S7 and the harmonic impedance characteristics of the power electronic converter in step S6; S9, superimposing the harmonic current disturbance value in step S8 on the initial harmonic disturbance, and combining it with the grid harmonic impedance matrix in step S5 to calculate a new harmonic voltage distribution; S10. Repeat steps S7 to S8 according to the harmonic voltage distribution of step S9 until the harmonic voltage converges, completing the iterative calculation of the harmonic voltage distribution of the distribution network.

2. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 1, characterized in that: In step S4, the equivalent parameters are calculated as follows: in, R is the equivalent resistance, X is the equivalent reactance, P is the active power of the node, Q is the reactive power of the node, U is the effective value of the voltage at the node.

3. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 1, characterized in that: In step S5, the grid harmonic impedance matrix is ​​calculated by respectively calculating the corresponding impedance matrix under each harmonic. The specific calculation process is as follows: Calculate the line impedance and the equivalent impedance of the load according to the calculated harmonic frequency; list the node admittance matrix of the grid; perform the inverse operation on the node admittance matrix to obtain the final harmonic impedance matrix.

4. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 1, characterized in that: In step S6, the power electronic converter model includes harmonic state space and impedance modeling methods.

5. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 4, characterized in that: Harmonic Impedance Characteristics of Power Electronic Converters for: in, is the harmonic disturbance voltage, is the harmonic impedance value of the converter.

6. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 1, characterized in that: In step S7, the initial distribution of the harmonic voltage of the distribution network for: in, is the harmonic impedance matrix of the grid, is the harmonic emission characteristic of the harmonic source.

7. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 1, characterized in that: In step S8, the new harmonic current disturbance of the distribution network for: in, is the initial distribution of harmonic voltages in the distribution network, is the harmonic impedance value of the converter.

8. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 1, characterized in that: Steps S7 to S9 obtain a more accurate distribution network harmonic voltage distribution result that takes into account the converter characteristics through repeated iterations of harmonic voltage distribution and harmonic current calculation.

9. The iterative calculation method for harmonic voltage distribution in a distribution network according to claim 1, characterized in that: In step S9, the new harmonic voltage distribution for: in, is the harmonic impedance matrix of the grid, is the harmonic emission characteristic of the harmonic source, It is a new harmonic current disturbance in the distribution network.

10. A system for iterative calculation of harmonic voltage distribution in a distribution network, characterized in that: include: The parameter module obtains the load size of each node in the distribution network and the line impedance between nodes, and determines the access capacity and location of the power electronic converter and harmonic source; Obtain filter parameters and control methods for power electronic converters, and determine harmonic emission characteristics of harmonic sources ; Calculate the fundamental power flow of the distribution network based on node load conditions and line parameters; The calculation module, based on the power flow calculation results, equates the load on the distribution network node except the converter to a series load of resistance and inductance, and calculates the equivalent parameters; based on the line parameters and equivalent load, calculates the harmonic impedance matrix of the grid. ; The disturbance module obtains the harmonic impedance characteristics of the power electronic converter model based on the filter parameters and controller parameters of the power electronic converter. The harmonic emission characteristics of the harmonic source are used as the initial harmonic disturbance, and combined with the harmonic impedance matrix, the initial distribution of the harmonic voltage of the distribution network is calculated. The voltage module calculates the new harmonic current disturbance of the distribution network based on the harmonic voltage distribution and the harmonic impedance characteristics of the power electronic converter; The harmonic current disturbance value is superimposed on the initial harmonic disturbance, and the new harmonic voltage distribution is calculated by combining the grid harmonic impedance matrix; The output module repeats the process according to the new harmonic voltage distribution until the harmonic voltage converges, thus completing the iterative calculation of the harmonic voltage distribution of the distribution network.

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