Browsing by Author "ABENEZER KASSA USAMO"

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    IMPACT OF DISTRIBUTED GENERATION ON DISTRIBUTION NETWORK PROTECTION SCHEME AND ADAPTIVE PROTECTION COORDINATION USING HARRIS’ HAWKS OPTIMIZATION
    (Hawassa University, 2022-07-26) ABENEZER KASSA USAMO
    The Modern Power System which has grown both in size and complexity, that means requires fast, accurate and reliable Protective schemes for protecting major equipment’s and to maintain system stability and reliability. Distribution networks are evolving into active meshed networks with bidirectional power flow as the penetration of distributed generation (DG) sources is increasing. Interconnecting DG to an existing distribution system provides various benefits to several entities as for example the owner, utility, and the final user. DG provides an enhanced power quality, higher reliability of the distribution system and can peak shaves and fill valleys. Penetration of a DG into an existing distribution system has many impacts on the system, with the power system protection being one of the major issues. This necessitates the use of directional relaying schemes in these emerging active distribution networks. However, conventional directional overcurrent (OC) protection will not be adequate to protect these networks against the stochastic nature of DGs and the changing network architectures. Hence, this study proposes an adaptive directional overcurrent relay algorithm that determines optimal protection settings according to varying fault currents and paths induced by the DGs in active meshed distribution networks. Location and technology of the DG sources are changed to study the effect that these changes may have on the coordination of protective directional over-current relays (DOCR). Results are compared to that of the normal case to investigate the impact of the DG on the short circuit currents flowing through different branches of the network to deduce the effect on protective devices. This study presents an adaptive protection coordination scheme for optimal coordination of DOCRs in interconnected power networks with the impact of DG. The used coordination technique is the Harris Hawks Optimization (HHO), selected due to adaptive & time-varying parameters allows HHO to handle difficulties of search including local optimal solution, multi modality & deceptive optima. Adaptive relaying describes protection schemes that adjust settings and/or logic of operations based on the prevailing conditions of the system. These adjustments can help to avoid relay miss-operation. Adjustments could include, but are not limited to, the logging of data for post-mortem analysis, communication throughout the system, as well changing relay parameters. Several concepts will be discussed, one of which will be implemented to prove the value of the new tools available. The optimal coordination of DOCR is find by with MATLAB code using HHO technique and the adaptive protection scheme model will develop in DIgSILENT/Power Factory. The results validate the ability of the proposed protection scheme to capture the uncertainties of the DGs and determine optimal protection settings, while ensuring minimal operating time