| In recent years,with the proposal of the "30,60" dual carbon goals,the use of clean energy such as wind and light to provide power support for oil field platforms has become an important development direction.However,with the integration of distributed power sources such as wind and light,the topology of the power supply system for offshore oil field platforms has become more complex,posing higher requirements for the protection and fault detection of equipment related to oil field platforms.The submarine cable bears the task of connecting various sub platforms of oil and gas fields and achieving power transmission through distributed energy.During actual operation,submarine cables may experience high resistance faults due to external forces and their own losses.Compared with conventional submarine cable faults,the fault information after high resistance faults is weak,and fault detection is difficult.Existing protection methods cannot achieve effective protection.The main research content of this project is as follows:(1)Taking the power supply system of a specific offshore oil platform as the prototype,a new topology structure is constructed after the wind,light and storage are connected to the oil platform.The principle and characteristics of distributed generation units such as wind,light and storage are analyzed,and the corresponding mathematical model is established.To achieve a hybrid connection between the distributed DC side and the AC side power supply system,the control mode of the inverter and the neutral grounding mode of the power supply system are analyzed.Elaborate on the structural characteristics and failure reasons of cross-linked polyvinyl chloride submarine cables.Use Cassie arc model to construct arc high resistance faults and study the characteristics of high resistance faults in submarine cables.(2)By analyzing the differences in fault characteristics between the DC side and the AC side submarine cables after arc high resistance faults,high resistance fault detection is achieved on the AC side based on the arc high resistance fault and the sudden change in zero sequence current.At the same time,based on the difference in phase angle between the zero sequence current and zero sequence voltage on both sides of the faulty line after the fault,the fault zone is located;On the DC side,based on the sudden change characteristics of zero mode current faults,EMD decomposition is used to calculate different modal components,and a judgment threshold is set based on the difference in the cumulative slope near the singularity point of the highest frequency modal component to achieve DC side fault detection.A precise fault location method suitable for AC/DC systems is proposed by combining the CEEMD algorithm with the traveling wave method.(3)Use PSCAD/EMTDC to build an overall simulation model for the power supply system of offshore oil field platforms.Obtain electrical data through the built model,write fault detection and location code using MATLAB,and validate the protection method proposed in the article.The verification results indicate that the high resistance fault detection and fault location methods proposed in this article have high reliability and sensitivity. |
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