An Equivalent Modeling Method for Ocean Microgrid Groups Interconnected by Submarine Cables

Abstract

The purpose of the present invention is to address the deficiency of the existing research on the equivalent value of the external network of the marine micro-grid group, and provide an equivalent modeling method for the marine micro-grid group interconnected by submarine cables, which is characterized in that it is aimed at the change of submarine cable parameters and limited The data exchange of the ocean microgrid establishes a unified external network equivalent circuit, and establishes the parameter estimation equation of the external network equivalent circuit based on the covariance theory; then establishes a weight function according to the distance between the sampling time of the sampling point and the current time. The weight function is combined with the equivalent parameter estimation equation, and the equivalent parameters of the equivalent circuit are solved according to the measured values ​​of the voltage and current at the connection point within a period of time, and the obtained equivalent circuit is the equivalent value of the external network of the marine microgrid. circuit. The invention provides a mathematically rigorous analysis model, realizes the equivalent value of the external network under the condition of limited data exchange and the change of the parameters of the submarine cable, has strong adaptability to the change of the operation characteristic of the internal network, and has good equivalent effect.

Description

technical field [0001] The invention relates to the technical field of static equivalence of power systems, in particular to an equivalent modeling method of marine micro-grid groups interconnected through submarine cables. Background technique [0002] At present, more and more marine microgrids, such as marine renewable energy fields, all-electric ships, and offshore oil and gas platforms, are interconnected to improve energy efficiency and better control emissions. The interconnection of different types of marine microgrids with “plug and play” functionality is also becoming more popular. Therefore, in order to realize the functional evaluation and the analysis of the operating characteristics of the connected marine microgrid system, it is necessary to establish a complete marine microgrid model. However, because these marine microgrids are far apart and the marine environment is harsh and changeable, it is difficult to collect detailed data of each local microgrid to e...

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Problems solved by technology

[0003] The existing research on equivalent modeling of external networks only focuses on land power grids, and the equivalent modeling of land external networks is more complicated, requiring more measurement points, and land power grids are connected by transmission lines. In the analysis of external network equivalents, it is considered that The parameters of the line are constant, that is, the influence of the change of the parameters of the transmission line on the equivalent effect is not considered

Yan Wei, Li Shiming, Chen Jun, Lu Jiangang, Guo Lin, Li Qin, Zhao Xia. Estimation method of static equivalent parameters of two-port external network based on measured information of internal network[J]. Chinese Journal of Electrical Engineering, 2011,31(13) :101-106; Liu Zhiwen, Liu Mingbo. Multi-area reactive power optimization decomposition coordination algorithm based on Ward equivalent[J]. Electric Power System Automation, 2010,34(14):63-69. When using long-distance submarine cables to transmit power, it will not only consume a certain amount of active power to cause network loss like ordinary land transmission lines, but also cause the reactive power passing through the submarine cables to change in voltage due to the large capacitive effect of the submarine cables. Especially sensitive, but more importantly, the parameters of the submarine cable will change with aging. When the parameters of the submarine cable change, it may affect the performance of the entire offshore system

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