Development of a Directional Definite-Time Overcurrent and Earth Fault Protection based on COTS Components

Abstract: Manufactures of power system products face an increased pressure to reduce the time to market of their development process without compromising quality. Moreover the operationof power systems needs to be performed in a secure and reliable manner. One ofthe key systems to guarantee those stringent requirements is the protection system. Theobjective of this Master’s thesis is the development of a protection system, which solidlyrelies on Commerciall-o↵-the-Shelf (COTS) components as well as on the developed protection functions. Thereby it is shown that the tight cost requirements can be fulfilled without jeopardising the reliability and security performance.This project comprises the development of a definite-time directional overcurrent andearth fault protection. The applied development process is based on a model-based-designapproach, which comprises the definition of the requirements, the design phase, the implementationon the target system and the test phase. As part of this thesis each stageis described and executed. Moreover MATLAB/Simulink was used as development environment,since it perfectly supports the model-based-design approach. The considered functional requirements are mostly based on the standard IEC 60255-151. The developed protection algorithm runs on a realtime linux system and the interface to the process isbased on the EtherCAT protocol and their corresponding I/O modules. Lastly, the testphase is based on a functional performance test, a type test according to IEC 60255-151,a longterm test and an evaluation of the EMC performance of the used I/O modules.The results of the type tests showed that a IEC 60255-151 compliant solution is yield. Moreover the functional performance test proofed that the developed protection function operate as intended for various fault scenarios. Lastly, the realtime performance of protection system has to be further analysed and adapted in order to achieve satisfactory behaviour.i