Large power grid harmonic calculation method and system considering conventional direct current and flexible direct current

Abstract

The invention discloses a large power grid harmonic calculation method and system considering conventional direct current and flexible direct current, and belongs to the technical field of power system harmonic simulation. The method comprises the following steps: acquiring power grid operation mode data of a power grid, and constructing harmonic models of various elements of the power grid based on the power grid operation mode data; judging whether the current power grid operation mode comprises conventional direct current and flexible direct current or not, if so, acquiring operation data of the conventional direct current and the flexible direct current from the operation mode, and calculating harmonic source values of the conventional direct current and the flexible direct current at an alternating current side node based on the operation data; and inputting the harmonic source numerical value on the one or more nodes, carrying out load flow calculation based on the harmonic model and the operation data, and generating a calculation result of each harmonic. According to the method, the influence of harmonic waves generated by conventional direct current and flexible direct current in a normal operation state on the power grid can be considered, and the accuracy of large power grid harmonic wave calculation can be improved.

Description

Technical Field

[0001] This invention relates to the field of power system harmonic simulation technology, and more specifically, to a method and system for calculating harmonics in a large power grid that considers both conventional DC and flexible DC. Background Technology

[0002] High-voltage direct current (HVDC) transmission technology is widely used in domestic and international power grids due to its advantages such as long transmission distance and large capacity. It plays an important role in my country's West-to-East Power Transmission and renewable energy consumption, and the number of HVDC projects is increasing year by year. The stable operation of HVDC projects is crucial to the safety and stability of the entire power grid. Under the background of new power systems, with the large-scale application and integration of complex power electronic equipment such as conventional HVDC and flexible HVDC into the power system, high-frequency harmonics will inevitably propagate in the large power grid. Under certain conditions, harmonic amplification and resonance may occur, leading to the shutdown or even outage of the HVDC transmission system.

[0003] Harmonics propagate and evolve in large power grids, causing equipment connected to the grid to become unstable or even suffer insulation breakdown. They also generate additional harmonic losses in the equipment, reducing operating efficiency. Furthermore, they can affect secondary measuring devices, causing relay protection equipment to malfunction, thus endangering the safe and stable operation of the power grid.

[0004] Current power grid harmonic simulation calculations need to be divided into two types: electromagnetic transient calculations and electromechanical transient calculations. Electromagnetic transient harmonic calculations require detailed models of conventional DC and flexible DC systems, but only simple power grid harmonic models can be established on the grid side, making it impossible to model electromagnetic transient harmonics for large-scale power grids. Current electromechanical transient harmonic calculations mainly use linear calculation methods based on harmonic current source injection, which can use actual large-scale power grid harmonic models, but cannot consider the actual operating parameters of conventional DC and flexible DC systems. Summary of the Invention

[0005] To address the above problems, this invention proposes a method for calculating harmonics in large power grids that considers both conventional DC and flexible DC transmission, comprising:

[0006] Obtain power grid operation mode data, and construct harmonic models for various power grid components based on the power grid operation mode data;

[0007] Determine whether the current power grid operation mode includes conventional DC and flexible DC. If so, obtain the operation data of conventional DC and flexible DC from the operation mode, and calculate the harmonic source values ​​of conventional DC and flexible DC at the AC side node based on the operation data.

[0008] Select one or more nodes in the running data, and input the harmonic source values ​​at the one or more nodes. Perform power flow calculation based on the harmonic model and the running data, and generate the calculation results for each harmonic.

[0009] Optional harmonic models include: line harmonic model, load harmonic model, transformer harmonic model, and filter harmonic model;

[0010] The line harmonic model includes: IEEE AC line model, AC line distributed parameter model and IEEE cable model;

[0011] The load harmonic model includes: a parallel load model, a load model containing motors, an RL series load model, a resistor-reactor hybrid branch model, and a harmonic source model. The parallel load model is used to represent concentrated loads, the RL series load model is used to represent single loads, and the resistor-reactor hybrid branch model is used to represent combined loads.

[0012] The transformer harmonic models include: conventional transformer models, CIGRE transformer models, and IEEE transformer models;

[0013] The aforementioned filter harmonic model includes: a general passive filter model used to filter out harmonics of a specific order.

[0014] Optional harmonic source values ​​include: ordinary harmonic source values, conventional DC harmonic source values, and flexible DC harmonic source values;

[0015] The common harmonic source refers to a harmonic current source that is input into a node of the power grid and propagates from the injection node to the entire grid.

[0016] The conventional DC harmonic source refers to the harmonic current generated by conventional DC during normal operation;

[0017] The flexible DC harmonic source refers to the harmonic current generated by a flexible DC power source during normal operation.

[0018] Optional, current flow calculations include:

[0019] Call the harmonic power flow calculation program to perform harmonic power flow calculations and generate calculation results, including:

[0020] Based on power grid operation data, a power grid harmonic network is generated, and the harmonic parameters of each component are calculated.

[0021] Enter the harmonic source data. If the power grid contains conventional DC and flexible DC components, the harmonic source values ​​of conventional DC and flexible DC will be automatically calculated.

[0022] Call the harmonic power flow calculation program to determine the distribution of harmonic currents and the degree of distortion of voltage and current waveforms in each part.

[0023] Furthermore, this invention also proposes a large-scale power grid harmonic calculation system considering both conventional DC and flexible DC, comprising:

[0024] The data and model management unit is used to acquire power grid operation mode data and, based on the power grid operation mode data, construct harmonic models for various power grid components.

[0025] The judgment unit is used to determine whether the current power grid operation mode includes conventional DC and flexible DC. If it does, it obtains the operation data of conventional DC and flexible DC from the operation mode and calculates the harmonic source values ​​of conventional DC and flexible DC at the AC side node based on the operation data.

[0026] The calculation unit is used to select one or more nodes in the running data, input the harmonic source values ​​at the one or more nodes, perform power flow calculation based on the harmonic model and the running data, and generate the calculation results of each harmonic.

[0027] Optional harmonic models include: line harmonic model, load harmonic model, transformer harmonic model, and filter harmonic model;

[0028] The line harmonic model includes: IEEE AC line model, AC line distributed parameter model and IEEE cable model;

[0029] The load harmonic model includes: a parallel load model, a load model containing motors, an RL series load model, a resistor-reactor hybrid branch model, and a harmonic source model. The parallel load model is used to represent concentrated loads, the RL series load model is used to represent single loads, and the resistor-reactor hybrid branch model is used to represent combined loads.

[0030] The transformer harmonic models include: conventional transformer models, CIGRE transformer models, and IEEE transformer models;

[0031] The aforementioned filter harmonic model includes: a general passive filter model used to filter out harmonics of a specific order.

[0032] Optional harmonic source values ​​include: ordinary harmonic source values, conventional DC harmonic source values, and flexible DC harmonic source values;

[0033] The common harmonic source refers to a harmonic current source that is input into a node of the power grid and propagates from the injection node to the entire grid.

[0034] The conventional DC harmonic source refers to the harmonic current generated by conventional DC during normal operation;

[0035] The flexible DC harmonic source refers to the harmonic current generated by a flexible DC power source during normal operation.

[0036] Optional, current flow calculations include:

[0037] Call the harmonic power flow calculation program to perform harmonic power flow calculations and generate calculation results, including:

[0038] Based on power grid operation data, a power grid harmonic network is generated, and the harmonic parameters of each component are calculated.

[0039] Enter the harmonic source data. If the power grid contains conventional DC and flexible DC components, the harmonic source values ​​of conventional DC and flexible DC will be automatically calculated.

[0040] Call the harmonic power flow calculation program to determine the distribution of harmonic currents and the degree of distortion of voltage and current waveforms in each part.

[0041] In another aspect, the present invention also provides a computing device, comprising: one or more processors;

[0042] A processor is used to execute one or more programs;

[0043] When the one or more programs are executed by the one or more processors, the method described above is implemented.

[0044] In another aspect, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the method described above.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] This invention proposes a method for calculating harmonics in a large power grid that considers both conventional DC and flexible DC transmission. The method includes: acquiring power grid operation mode data; constructing harmonic models for various power grid components based on the operation mode data; determining whether the current power grid operation mode includes conventional DC and flexible DC transmission; if so, acquiring the operation data of conventional DC and flexible DC transmission from the operation mode data, and calculating the harmonic source values ​​of conventional DC and flexible DC transmission at AC-side nodes based on the operation data; selecting one or more nodes from the operation data, inputting the harmonic source values ​​at the selected nodes, performing power flow calculations based on the harmonic models and operation data, and generating calculation results for each harmonic. This invention can consider the impact of harmonics generated by conventional DC and flexible DC transmission under normal operating conditions on the power grid, thus improving the accuracy of harmonic calculations in large power grids. Attached Figure Description

[0047] Figure 1 This is a flowchart of the method of the present invention;

[0048] Figure 2This is a structural diagram of the system of the present invention. Detailed Implementation

[0049] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0050] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0051] Example 1:

[0052] This invention proposes a method for calculating harmonics in large power grids that considers both conventional DC and flexible DC transmission, such as... Figure 1 As shown, it includes:

[0053] Step 1: Obtain power grid operation mode data, and based on the power grid operation mode data, construct harmonic models for various power grid components;

[0054] Step 2: Determine whether the current power grid operation mode includes conventional DC and flexible DC. If it does, obtain the operation data of conventional DC and flexible DC from the operation mode, and calculate the harmonic source values ​​of conventional DC and flexible DC at the AC side node based on the operation data.

[0055] Step 3: Select one or more nodes in the running data, and input the harmonic source values ​​on the one or more nodes. Perform power flow calculation based on the harmonic model and the running data, and generate the calculation results for each harmonic.

[0056] Among them, the harmonic models include: line harmonic model, load harmonic model, transformer harmonic model and filter harmonic model;

[0057] The line harmonic model includes: IEEE AC line model, AC line distributed parameter model and IEEE cable model;

[0058] The load harmonic model includes: a parallel load model, a load model containing motors, an RL series load model, a resistor-reactor hybrid branch model, and a harmonic source model. The parallel load model is used to represent concentrated loads, the RL series load model is used to represent single loads, and the resistor-reactor hybrid branch model is used to represent combined loads.

[0059] The transformer harmonic models include: conventional transformer models, CIGRE transformer models, and IEEE transformer models;

[0060] The aforementioned filter harmonic model includes: a general passive filter model used to filter out harmonics of a specific order.

[0061] Among them, the harmonic source values ​​include: ordinary harmonic source values, conventional DC harmonic source values, and flexible DC harmonic source values;

[0062] The common harmonic source refers to a harmonic current source that is input into a node of the power grid and propagates from the injection node to the entire grid.

[0063] The conventional DC harmonic source refers to the harmonic current generated by conventional DC during normal operation;

[0064] The flexible DC harmonic source refers to the harmonic current generated by a flexible DC power source during normal operation.

[0065] Power flow calculation includes:

[0066] Call the harmonic power flow calculation program to perform harmonic power flow calculations and generate calculation results, including:

[0067] Based on power grid operation data, a power grid harmonic network is generated, and the harmonic parameters of each component are calculated.

[0068] Enter the harmonic source data. If the power grid contains conventional DC and flexible DC components, the harmonic source values ​​of conventional DC and flexible DC will be automatically calculated.

[0069] Call the harmonic power flow calculation program to determine the distribution of harmonic currents and the degree of distortion of voltage and current waveforms in each part.

[0070] The invention will be further explained below with specific examples:

[0071] The method of this invention is implemented through the following modules, which include:

[0072] Data management, harmonic model management, harmonic source input, harmonic calculation and result output.

[0073] As a further aspect of the present invention: the data management refers to the management of power grid operation mode data that requires harmonic calculation.

[0074] As a further aspect of the present invention: the harmonic model management refers to the harmonic models of various components in the power grid operation mode data, including the harmonic models of lines, loads, transformers, and filters.

[0075] As a further aspect of the present invention: the line harmonic model includes an IEEE AC line model, an AC line distributed parameter model, and an IEEE cable model.

[0076] As a further aspect of the present invention: the load harmonic model includes a parallel load model, a load model containing a motor, an RL series load model, a mixed branch of resistors and reactances, and a harmonic source model.

[0077] Parallel load model: suitable for representing concentrated loads.

[0078] R(h)=R p =V 2 / P

[0079] X(h)=hX p =hV 2 / Q

[0080] In the formula: V is the node voltage where the load is located, P is the active power of the load, Q is the reactive power of the load, Rp is the fundamental resistance of the load, Xp is the fundamental reactance of the load, and h is the harmonic order.

[0081] RL series load model: suitable for representing a single load.

[0082]

[0083] R(h)=Rs

[0084] X(h)=hXs

[0085] S = p + jQ

[0086] |S| 2 =p 2 +Q 2

[0087] In the formula: S is the apparent power of the load, P is the active power of the load, Q is the reactive power of the load, Rs is the fundamental resistance of the load, Xs is the fundamental reactance of the load, and h is the harmonic order.

[0088] Mixed resistance and reactance branch load: Applicable to combined loads.

[0089] Its resistance and reactance values ​​are as follows:

[0090] R s =V 2 / P

[0091] X S =0.073hR S

[0092]

[0093] In the formula: P and Q are the "natural" active and reactive power values ​​of the load at the fundamental frequency, respectively. The so-called "natural" power value refers to the original active and reactive power values ​​without artificial compensation, that is, the power values ​​before the capacitors installed to improve the power factor are taken into account. h is the harmonic order, and Rs is the fundamental frequency resistance.

[0094] As a further aspect of the present invention: the transformer harmonic model includes a conventional transformer model, a CIGRE transformer model, and an IEEE transformer model.

[0095] The formula for calculating harmonics in a conventional transformer model is shown below:

[0096] Z Th =h 1.15 R T1 +jhX T1

[0097] In the formula: h is the harmonic order;

[0098] R T1 This is the winding resistance of the fundamental wave transformer;

[0099] X T1 This is the corresponding sequence reactance of the fundamental transformer.

[0100] The CIGRE transformer harmonic model calculation formula is as follows:

[0101] X Tk =hX T1

[0102]

[0103] In the formula: U N 、S N These are the transformer's rated voltage and rated capacity, respectively.

[0104] R T1 This is the winding resistance of the fundamental wave transformer;

[0105] X T1 This is the corresponding sequence reactance of the fundamental transformer.

[0106] The IEEE transformer harmonic model calculation formula is shown below:

[0107]

[0108] In the formula: h is the harmonic order;

[0109] R T1 This is the winding resistance of the fundamental wave transformer;

[0110] X T1 This is the corresponding sequence reactance of the fundamental transformer.

[0111] As a further aspect of the present invention: the filter harmonic model refers to a general passive filter model used to filter out harmonics of a specific order.

[0112] Different filter models can be implemented by setting the general parameters of the filter model. The parameter setting methods for each filter model are shown in Table 1.

[0113] Table 1

[0114] Model Number R1 L1 C1 R2 L2 C2 1. Standard type 0 efficient efficient ∞ ∞ ∞ 2 (First-order reduction) efficient 0 efficient ∞ ∞ ∞ 3 (Second-order reduction) efficient 0 efficient 0 efficient 0 4 (Third-order reduction) 0 efficient efficient efficient 0 efficient 5 (Single-tuned) efficient efficient efficient ∞ ∞ ∞ 6 (High-Pass Undamped) 0 efficient efficient 0 0 efficient 7 (High-Pass Damped) efficient 0 efficient efficient efficient 0 8 (By-Pass) 0 efficient efficient 0 efficient efficient 9 (Type C) efficient 0 efficient 0 efficient efficient

[0115] As a further aspect of the present invention: the harmonic source input refers to inputting harmonic source parameters into one or more nodes in the power grid operation mode data, including ordinary harmonic sources, conventional DC harmonic sources and flexible DC harmonic sources.

[0116] As a further aspect of the present invention: the ordinary harmonic source refers to a harmonic current source input into a node of the power grid, which propagates from the injection node to the entire network.

[0117] As a further aspect of the present invention: the conventional DC harmonic model refers to the harmonic current generated by conventional DC during normal operation.

[0118]

[0119] Where h is the harmonic order, I1 is the effective value of the fundamental current during normal DC operation, and I h α is the harmonic current, α is the firing angle of conventional DC, and μ is the commutation angle of conventional DC.

[0120]

[0121] As a further aspect of the present invention: the flexible DC harmonic source refers to the harmonic current generated by the flexible DC during normal operation.

[0122] The expression for the flexible harmonic current I h for:

[0123]

[0124] In the formula, The harmonic voltage of flexible DC under the modulation strategy. The harmonic voltage of flexible DC under dead time. It is the harmonic impedance of flexible DC.

[0125]

[0126] To calculate the maximum value of the flexible DC harmonic voltage under the modulation strategy, we take sin(hω1t) = 1.

[0127]

[0128] Where: h represents the harmonic order, satisfying h = 6i ± 1, i = 1, 2, 3, ...; N represents the number of modules in the flexible DC transmission; v c The capacitor voltage of the flexible DC submodule under ideal conditions is represented by: vc = vdc / N; M is the voltage modulation ratio, which satisfies M = 2va / vdc; φ is the power factor angle of the flexible DC.

[0129]

[0130] To calculate the maximum harmonic voltage of flexible DC under dead time, we take sin(hω1t-hα) i1 -hω1t d / 2-hπ / 2)=1,sin(hω1t-hα i2 -hω1t d / 2-hπ / 2)=1,sin(hω1t-hα i3 -hω1t d ( / 2-hπ / 2)=1, then

[0131]

[0132] Where: t d Represents the dead time; k is the current modulation ratio, satisfying k = (I a / 2) / (I dc / 3); I a For alternating current, I dc The current is direct current, cosφ is the power factor, mkcosφ=2, ω1=2πf1, f1=50Hz

[0133]

[0134] The expression for the harmonic impedance of flexible DC is as follows:

[0135]

[0136] Where Φ is the phase difference between AC voltage and current, I1 is the amplitude of the three-phase AC current during steady-state operation, V1 is the amplitude of the three-phase AC voltage during steady-state operation; G1 is the open-loop transfer function of the inner current loop, Kd K is the decoupling coefficient of the inner current loop. d =0.5ω1L arm i d0 i q0 These are the steady-state currents along the d and q axes, respectively, G P L is the open-loop transfer function of the power outer loop; eq =L arm / 2,R eq =R arm / 2,L arm and R arm These represent the bridge arm inductance and bridge arm resistance, respectively; ω1 = 2πf1, f1 = 50Hz; G1 = k pi +k ii / s,k pi k is the proportionality coefficient of the inner current loop. ii G is the integral coefficient of the inner current loop; P =k pp +k ip / s,k pp k is the proportional gain of the active power system. ip G is the integral coefficient of the active power element; PLL =T PLL / (1+V1T PLL ), k ppll k is the proportional gain of the phase-locked loop. ipll The integral coefficients of the phase-locked loop; s = j2πf h j is the imaginary unit, f h This refers to the harmonic frequency.

[0137] As a further aspect of the present invention: the harmonic calculation refers to calling a harmonic power flow calculation program to perform harmonic power flow calculation and generate calculation results.

[0138] Based on power grid operation data, a power grid harmonic network is generated, and the harmonic parameters of each component are calculated. Harmonic source data is entered; if the power grid contains conventional DC and flexible DC components, the harmonic source values ​​for conventional DC and flexible DC are automatically calculated. The harmonic power flow calculation program is invoked to determine the distribution of harmonic currents and the degree of distortion of voltage and current waveforms in each part.

[0139] As a further aspect of the present invention: the result output refers to the output interface of the harmonic power flow calculation results for viewing.

[0140] Based on the distribution of harmonic currents and the voltage and current waveforms of each part, the harmonic voltage distortion rate is calculated and compared with the allowable value of branch harmonic current to determine whether the harmonics at the common coupling point exceed the standard, and the relevant values ​​are displayed to the user for viewing.

[0141] Example 2:

[0142] This invention also proposes a large power grid harmonic calculation system 200 that considers both conventional DC and flexible DC, such as... Figure 2 As shown, it includes:

[0143] The data and model management unit 201 is used to acquire power grid operation mode data and construct harmonic models of various power grid components based on the power grid operation mode data.

[0144] The judgment unit 202 is used to determine whether the current power grid operation mode includes conventional DC and flexible DC. If it does, it obtains the operation data of conventional DC and flexible DC from the operation mode and calculates the harmonic source values ​​of conventional DC and flexible DC at the AC side node based on the operation data.

[0145] The calculation unit 203 is used to select one or more nodes in the running data, input the harmonic source values ​​at the one or more nodes, perform power flow calculation based on the harmonic model and the running data, and generate the calculation results of each harmonic.

[0146] Among them, the harmonic models include: line harmonic model, load harmonic model, transformer harmonic model and filter harmonic model;

[0147] The line harmonic model includes: IEEE AC line model, AC line distributed parameter model and IEEE cable model;

[0148] The load harmonic model includes: a parallel load model, a load model containing motors, an RL series load model, a resistor-reactor hybrid branch model, and a harmonic source model. The parallel load model is used to represent concentrated loads, the RL series load model is used to represent single loads, and the resistor-reactor hybrid branch model is used to represent combined loads.

[0149] The transformer harmonic models include: conventional transformer models, CIGRE transformer models, and IEEE transformer models;

[0150] The aforementioned filter harmonic model includes: a general passive filter model used to filter out harmonics of a specific order.

[0151] Among them, the harmonic source values ​​include: ordinary harmonic source values, conventional DC harmonic source values, and flexible DC harmonic source values;

[0152] The common harmonic source refers to a harmonic current source that is input into a node of the power grid and propagates from the injection node to the entire grid.

[0153] The conventional DC harmonic source refers to the harmonic current generated by conventional DC during normal operation;

[0154] The flexible DC harmonic source refers to the harmonic current generated by a flexible DC power source during normal operation.

[0155] Power flow calculation includes:

[0156] Call the harmonic power flow calculation program to perform harmonic power flow calculations and generate calculation results, including:

[0157] Based on power grid operation data, a power grid harmonic network is generated, and the harmonic parameters of each component are calculated.

[0158] Enter the harmonic source data. If the power grid contains conventional DC and flexible DC components, the harmonic source values ​​of conventional DC and flexible DC will be automatically calculated.

[0159] Call the harmonic power flow calculation program to determine the distribution of harmonic currents and the degree of distortion of voltage and current waveforms in each part.

[0160] Example 3:

[0161] Based on the same inventive concept, this invention also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, 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 and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement corresponding method flows or corresponding functions, thereby implementing the steps of the methods in the above embodiments.

[0162] Example 4:

[0163] Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiments.

[0164] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0165] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. 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.

[0166] 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.

[0167] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating 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 The steps of the function specified in one or more boxes.

[0168] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0169] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for calculating harmonics in a large power grid considering both conventional DC and flexible DC, characterized in that, include: Obtain power grid operation mode data, and construct harmonic models for various power grid components based on the power grid operation mode data; Determine whether the current power grid operation mode includes conventional DC and flexible DC. If so, obtain the operation data of conventional DC and flexible DC from the operation mode, and calculate the harmonic source values ​​of conventional DC and flexible DC at the AC side node based on the operation data. Select one or more nodes in the running data, and input the harmonic source values ​​at the one or more nodes. Perform power flow calculation based on the harmonic model and the running data, and generate the calculation results for each harmonic.

2. The method for calculating harmonics in a large power grid according to claim 1, characterized in that, The harmonic model includes: line harmonic model, load harmonic model, transformer harmonic model and filter harmonic model; The line harmonic model includes: IEEE AC line model, AC line distributed parameter model and IEEE cable model; The load harmonic model includes: a parallel load model, a load model containing motors, an RL series load model, a resistor-reactor hybrid branch model, and a harmonic source model. The parallel load model is used to represent concentrated loads, the RL series load model is used to represent single loads, and the resistor-reactor hybrid branch model is used to represent combined loads. The transformer harmonic models include: conventional transformer models, CIGRE transformer models, and IEEE transformer models; The aforementioned filter harmonic model includes: a general passive filter model used to filter out harmonics of a specific order.

3. The method for calculating harmonics in a large power grid according to claim 1, characterized in that, The harmonic source values ​​include: ordinary harmonic source values, conventional DC harmonic source values, and flexible DC harmonic source values; The common harmonic source refers to a harmonic current source that is input into a node of the power grid and propagates from the injection node to the entire grid. The conventional DC harmonic source refers to the harmonic current generated by conventional DC during normal operation; The flexible DC harmonic source refers to the harmonic current generated by a flexible DC power source during normal operation.

4. The method for calculating harmonics in a large power grid according to claim 1, characterized in that, The power flow calculation includes: Call the harmonic power flow calculation program to perform harmonic power flow calculations and generate calculation results, including: Based on power grid operation data, a power grid harmonic network is generated, and the harmonic parameters of each component are calculated. Enter the harmonic source data. If the power grid contains conventional DC and flexible DC components, the harmonic source values ​​of conventional DC and flexible DC will be automatically calculated. Call the harmonic power flow calculation program to determine the distribution of harmonic currents and the degree of distortion of voltage and current waveforms in each part.

5. A large power grid harmonic calculation system considering both conventional DC and flexible DC, characterized in that, include: The data and model management unit is used to acquire power grid operation mode data and, based on the power grid operation mode data, construct harmonic models for various power grid components. The judgment unit is used to determine whether the current power grid operation mode includes conventional DC and flexible DC. If it does, it obtains the operation data of conventional DC and flexible DC from the operation mode and calculates the harmonic source values ​​of conventional DC and flexible DC at the AC side node based on the operation data. The calculation unit is used to select one or more nodes in the running data, input the harmonic source values ​​at the one or more nodes, perform power flow calculation based on the harmonic model and the running data, and generate the calculation results of each harmonic.

6. The large power grid harmonic calculation system according to claim 5, characterized in that, The harmonic model includes: line harmonic model, load harmonic model, transformer harmonic model and filter harmonic model; The line harmonic model includes: IEEE AC line model, AC line distributed parameter model and IEEE cable model; The load harmonic model includes: a parallel load model, a load model containing motors, an RL series load model, a resistor-reactor hybrid branch model, and a harmonic source model. The parallel load model is used to represent concentrated loads, the RL series load model is used to represent single loads, and the resistor-reactor hybrid branch model is used to represent combined loads. The transformer harmonic models include: conventional transformer models, CIGRE transformer models, and IEEE transformer models; The aforementioned filter harmonic model includes: a general passive filter model used to filter out harmonics of a specific order.

7. The large power grid harmonic calculation system according to claim 5, characterized in that, The harmonic source values ​​include: ordinary harmonic source values, conventional DC harmonic source values, and flexible DC harmonic source values; The common harmonic source refers to a harmonic current source that is input into a node of the power grid and propagates from the injection node to the entire grid. The conventional DC harmonic source refers to the harmonic current generated by conventional DC during normal operation; The flexible DC harmonic source refers to the harmonic current generated by a flexible DC power source during normal operation.

8. The large power grid harmonic calculation system according to claim 5, characterized in that, The power flow calculation includes: Call the harmonic power flow calculation program to perform harmonic power flow calculations and generate calculation results, including: Based on power grid operation data, a power grid harmonic network is generated, and the harmonic parameters of each component are calculated. Enter the harmonic source data. If the power grid contains conventional DC and flexible DC components, the harmonic source values ​​of conventional DC and flexible DC will be automatically calculated. Call the harmonic power flow calculation program to determine the distribution of harmonic currents and the degree of distortion of voltage and current waveforms in each part.

9. A computer device, characterized in that, include: One or more processors; A processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the method described in any one of claims 1-4 is implemented.

10. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the method as described in any one of claims 1-4.

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