Research On Fault Line Selection Method For Single-line-to-ground Fault In Offshore Multi-platform Interconnected Power System

With the continuous expansion of the exploitation scale of offshore oil fields,as an important guarantee for the development of marine resources,the safe and stable operation of the offshore multi-platform interconnected power system has become a research trend.Due to the characteristics of marine environment and offshore power system platform,single-phase ground faults are more likely to occur.When a singleline-to-ground fault occurs in the offshore multi-platform interconnected power system,the system can quickly and accurately select the faulty line and take corresponding measures to make the production work proceed normally,so the study of line selection method in single-line-to-ground fault is of great significance.Firstly,the single-line-to-ground fault characteristics of a single-generator and multiple-feeder platform in an offshore multi-platform interconnected power system are analyzed.Mathematical modeling is used to analyze the magnitude and composition of the zero-mode current of each line after the fault,and a simulation model is built to simulate the single-generator and multi-feeder platform topology system.The zeromode current characteristics of the faulty line and the non-faulty line are analyzed and compared.Secondly,a multi-criteria fusion line selection algorithm based on D-S evidence theory is proposed.This algorithm can be effectively applied to actual offshore multiplatform interconnected power system,and shows high line selection accuracy.This algorithm combines three independent line selection methods: the intrinsic mode function energy coefficient method;the AM-FM function energy coefficient method;the high-frequency transient capacitor current energy coefficient method.These three line selection algorithms can be used alone as the selection method,but each has its own shortcomings.The intrinsic mode function energy coefficient method is affected by its own theory shortcomings,causing problems such as mode mixing and end effect.The AM-FM function energy coefficient method and high-frequency transient capacitor current energy coefficient method is significantly affected by noise.In this paper,the three line selection algorithms are studied in detail,and their advantages and disadvantages are analyzed.This article introduces two denoising methods,namely EMD denoising method and bistable system denoising method,and verify its denoising effect by simulation.Thirdly,considering the future development of offshore multi-platform interconnected power system,a multi-platform interconnected power system model with various interconnections and relatively complete topology is built,and transient electromagnetic simulation software EMTP-RV is used to simulate single-line-toground faults,to verify the multi-criteria fusion line selection algorithm.Finally,the topology of the actual offshore multi-platform interconnected power system and its electrical equipment are introduced.Considering the demanded operating speed,RT-LAB is used to model and simulate the actual offshore multiplatform interconnected power system,verifying the feasibility of the multi-criteria fusion line selection algorithm.