System harmonic impedance estimation method and system based on minimum impedance and voltage norm
A harmonic impedance and norm technology, applied in the field of system harmonic impedance estimation, can solve problems that are not suitable for new scenarios of power grids, background harmonic fluctuations of power grids, etc.
Active Publication Date: 2020-02-07
STATE GRID SICHUAN ELECTRIC POWER CORP ELECTRIC POWER RES INST
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However, in the current power electronic power system, the number of harmonic sources increases, the interaction of each harmonic source and the change of the network operation mode, the background harmonics in the power grid fluctuate; at the same time, the user side usually installs filters and Reactive power compensation capacitor device, in some frequency components, the harmonic impedance of the user side is not much larger than the harmonic impedance of the system side
Most of the existing methods are based on the assumption that the background harmonics are stable and the user-side harmonic impedance is much larger than the system-side harmonic impedance, which will not be suitable for the new power grid scenario of existing power electronics.
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[0094] In order to understand the above-mentioned purpose, features and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, under the condition of not conflicting with each other, the embodiments of the present application and the features in the embodiments can be combined with each other.
[0095] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from the scope of this description. Therefore, the protection scope of the present invention is not limited by the following disclosure. limitations of specific examples.
[0096] Those skilled in the art should understand that in the disclosure of the present invention, the terms "vertical", "transverse", "upper", "lower", "front",...
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The invention discloses a system harmonic impedance estimation method and system based on minimum impedance and voltage norm. The method comprises the following steps of step (A), sampling the harmonic voltage and current at a PCC (Point of Common Coupling) in a power grid within a preset time period, obtaining measurement data of the harmonic voltage and current within the preset time period, andestablishing a PCC system side circuit equation, wherein the PCC is the point of common coupling; step (B), for the measurement data of the harmonic voltage and current in step (A), according to an equivalent circuit equation at the PCC, the system side harmonic impedance, and the system side harmonic voltage norm minimization criterion, establishing an optimization equation of a sampling sub-interval; and step (C), based on a gradient descent method, iteratively solving the optimization equation established in step (B) to obtain a solution result, and substituting the solution result into the PCC system side circuit equation to calculate and obtain the system side harmonic impedance. The system harmonic impedance estimation method based on the minimum impedance and voltage norm providedby the invention meets the actual engineering needs, and has good estimation accuracy and low error.
Description
technical field [0001] The invention relates to the field of harmonic emission level and harmonic research in power quality in power grids, in particular to a method and system for estimating system harmonic impedance based on the minimum impedance and voltage norm. Background technique [0002] With the continuous development and application of power electronics technology in the power grid, the access of a large number of nonlinear loads, such as inverters and electric vehicle charging piles, has caused extremely serious harmonic pollution in the power grid. How to quantitatively divide the harmonic responsibilities of each harmonic source in the access system is the premise of realizing intelligent management and control of power quality, and the accurate calculation of harmonic impedance is the basis and key of responsibility division. [0003] Usually based on the equivalent circuit of the harmonic source, a common connection point (PCC) is selected, and the system side...
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IPC IPC(8): G01R27/16
CPCG01R27/16
Inventor 徐琳滕予非魏巍刘畅杨华唐伟
Owner STATE GRID SICHUAN ELECTRIC POWER CORP ELECTRIC POWER RES INST