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smart grid will be a power grid more “aware” of its operating state and having the ability to self-heal. These features may be incorporated into the grid by
implementing a phasor measurement units based wide area measurement system.
Such a system will help in better real time monitoring and control of the grid.
However, the wide area measurement system is subject to challenges with respect
to its security. In this paper, a comprehensive analysis of security issues with a wide area measurement system is presented
and the research efforts required to be taken are identified. Moreover, the effect
of communication failure on a PMU installed system has been presented using
integer linear programming.
The spot welds nugget cracking of austenitic stainless steel at temperatures between 700°C - 1010°C was investigated. Traditionally, the cracks have been observed around the spot nugget in welded temperature. Actually, these cracks are developed due to incomplete melting and inappropriate electrode pressure, which causes an expulsion of molten metal. These cracks start to grow and cause either the interface or plug fracture according to the loading type. In this work, the micro-cracks in the weld nugget were indicated for this type of steel at elevated temperature. Cracks appear in a certain range of temperature; about 700°C - 750°C. The cracks like defect and cavitations were presented. According to the fracture mechanics point of view, these cracks reduce the mechanical strength. Therefore, these cracks have to be taken into account with a certain precaution. Moreover, considering the working temperature and reducing the element may develop ferrite particles.