Research On Wireless Communication Technology For Distribution Network Protection

Externally pressurized gas bearing has been widely used in the field of aviation,semiconductor,weave,and measurement apparatus because of its advantage of high accuracy,little friction,low heat distortion,long life-span,and no pollution.In this thesis,based on the domestic and overseas researching……The traditional distribution network is mostly a single source radial network with a single power flow direction,and the relay protection method is based on three-stage current protection,with multiple stages working together to achieve full line protection,which is easier to set the protection va lue,but the action delay would not lead to a lack of quick-action protection.The increase in the proportion of distributed power supply into the network has made the distribution network gradually develop into a complex topology with multiple sources and ends,which makes the traditional protection principle that only considers the electrical sample data of a single end can no longer meet the four protection needs of the multi-source network,so the protection principle based on double-ended information to achieve full-line quick-action has become the first choice.The double-ended information principle of feeder automation and differential protection requires simultaneous comparison of data on both sides and usually uses optical fibre as the communication medium.Although the price of materials has fallen significantly,the complexity and variability of distribution lines makes the laying and maintenance of fibre optics difficult,so the promotion of this type of protection in the distribution network is slow.The emergence of 5G communication technology is not only an advancement in the communication industry,but also a new window for the upgrading of grid technology,which in theory can fully meet the communication index requirements of distribution network protection,while being low cost,easy to deploy and fast to maintain.Therefore,this thesis aims to realize the 5G of distribution network feeder automation,to study various problems of 5G communication in distribution network protection business,and to provide new ideas for the upgrading of distribution network protection business.Based on the above background,this thesis carries out several tasks as follows.(1)The reasons and solutions for the ineffectiveness of 5G communications were analysed when used as a communication method for distribution network services.Firstly,this thesis analyse the air-port link,which has the greatest impact on communication quality uncertainty,compare the impact caused by various physical factors,discuss the limitations of air-port technical factors,and propose the direction of D2 D technology application in the distribution network.The MEC deployment scheme is then demonstrated,focusing on the converged deployment of power facilities and security issues.Finally,the security vulnerabilities of various functional schemes of 5G power private networks are compared and analysed and improvement measures are proposed.(2)A feeder automation scheme based on 5G communication is proposed.Based on the characteristics of GOOSE messages used for STU interaction in the distribution network,the UDP multicast method is used to IP-enable the GOOSE protocol so that GOOSE messages can be interacted via 5G communication.Analyse the means of 5G communication to ensure low latency and high reliability of messages in the protocol,and improve the message transmission scheme according to the needs of the distribution network services.This thesis designs the topology identification technology using STU peer-to-peer wireless communication and feeder automation technology based on this to achieve fault isolation and non-faulty section recovery.(3)A method to dynamically adjust the STU waiting search time is proposed through machine learning for short-term prediction of delays to reduce the probability of device lockout due to delay problems.A Bayesian optimisation method is used to parameter optimize the Light GBM algorithm,and the prediction accuracy of the model is improved by K-fold cross-validation and optimal weight rationing.Then the trainnign and prediction is conducted on the dataset,and the prediction accuracy of the proposed algorithm is verified by comparing it with random forest and XGBoost algorithms.(4)A 5G communication feeder automation device is developed.Based on the above theoretical research,the hardware combination is selected for reliability and ease of use.And the feeder automation terminal capable of 5G communication is developed based on the traditional terminal.The terminal is tested on the real network,and the communication and protection functions of the device are tested so that it could reliably discriminate and act under various fault scenarios.