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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Digital secondary substations with auto-configuration of station monitoring through IEC 61850 and CIM

Wistedt, Johan January 2018 (has links)
This thesis explore the possibility to automate a process for configuration of secondary substations monitoring and control. By using a network information system (NIS), information of secondary substations can be extracted, such as feeder naming, primary equipment type, rating and model. From this information an automated process of configuring the secondary substation is possible, which open up the possibility to cost-efficiently digitalise the distribution grid. In the project, the standard IEC 61850 for configuration of communications of intelligent electrical devices was used to automate and standardize the process. The process starts with a extracted IEC 61970 CIM file from the NIS. The IEC 61970 CIM file is converted into a IEC 61850 SCL file through an system engineering tool. The configuration is based of information from the NIS, where the models and types of the equipments decides what type of functionality that is needed for the secondary substation. With help of the created SCL file hardware and human-machine interface (HMI) was configured, creating a full functional system for the secondary substation monitoring and control equipment. The usage of 400V capable input module together with bus couplers, configured in IEC 61850, lowers the configuration needed for the hardware. The usage of SCL files also helps automate the creation of HMI for the secondary substation through IEC 61850 based tools in SCADA software. Creating views of both single-line diagrams as well as digital representation of the secondary substation outgoing feeders with measured values on display. The result of the project helps show NIS information is sufficient and standards mature enough to allow an almost fully automated system. Lowering the total time spent on each stations configuration to around two hours. Leading the way for future development of automating software for configurations of the secondary substations.
2

Optimal nätdesign : Utvärdering och jämförelse av nätstrukturer i Stockholms mellanspänningsnät / Optimal grid design : Evaluation and comparison of network structures in Stockholm's MV-grid

Wennberg, Simon January 2017 (has links)
In today’s society the electric grid has become one of the most important infrastructures and industries as well as other infrastructures, and individuals rely on its functionality. The unavailability of electricity caused by outages is increasingly rare but when it occurs it can have serious consequences. An electric grid’s reliability is now a requirement, not only from customers but also from the regulatory authority.The electric grid in Stockholm is owned and operated by Ellevio AB. Over the past decade the reliability, measured in SAIDI (System Average Interruption Duration Index), in the area has deterioated, mainly due to failures of the medium voltage grid (11- kV, MV). The network structure on the MV- grid consists primarily of two parallel medium voltage cables each of which acts redundantly to its pair cable. The technique, called dual cable structure, works most optimally with substations with automatic switching, which automaticly switch over to the redundant cable when failure occurs. However substations without this automatic switching are widely used resulting in a longer interruption time. Another network structure is the ring or loop structure, which still has redundancy, but when failure occurs a load- break switch must close so that the grid can be fed from another direction. The substation in the loop structure can also be remotely controlled, making the load-break swith operable from the control center, resulting in a shorter interruption time.This thesis evaluates and compares different network structures consisting of dual cable with automatic switching and loop structure with remotely controlled substations, based on economy and reliability, on Stora Essingen. The two structures have been designed in the network information system program Trimble NIS and divided into two different environments; one developed and one undeveloped environment. The results show that the technical solutions in network structures of MV- grid do not necessarily mean major differences in economy nor reliability, rather the choice between few but long interruptions and many but short interruptions is central. Results show however that a combination of the dual cable structure with remotely controlled substations in the undeveloped environment is economically motivated while the reliability can be maintained at the same tame.

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