The effects of polar surface stabilization mechanisms on the film growth, phase composition, surface and interface structure, and magnetic properties are explored for polar (1×1) surfaces under equivalent conditions. This study suggests that in addition to the customary strain, spin, and band-gap engineering, control of surface polarity stabilization could also be important for electronic and magnetic device engineering.Cheung et al.2

This paper reports a new technique for achieving optimized design for power system stabilizers. In any large scale interconnected systems, disturbances of small magnitudes are very common and low frequency oscillations pose a major problem. Hence small signal stability analysis is very important for analyzing system stability and performance. Power System Stabilizers (PSS) are used in these large interconnected systems for damping out low-frequency oscillations by providing auxiliary control signals to the generator excitation input. In this paper, collective decision optimization (CDO) algorithm, a meta-heuristic approach based on the decision making approach of human beings, has been applied for the optimal design of PSS. PSS parameters are tuned for the objective function, involving eigenvalues and damping ratios of the lightly damped electromechanical modes over a wide range of operating conditions. Also, optimal locations for PSS placement have been derived. Comparative study of the results obtained using CDO with those of grey wolf optimizer (GWO), differential Evolution (DE), Whale Optimization Algorithm (WOA) and crow search algorithm (CSA) methods, established the robustness of the algorithm in designing PSS under different operating conditions.

This study analyzed the effects of applications of flexible alternating current transmission system (FACTS) devices, such as a thyristor controlled series capacitor (TCSC) and static var compensator (SVC) to handle the oscillations due to wind penetration in an existing network, and to exploit the AC lines to their thermal limits. A small signal stability analysis of an interconnected power system with wind penetration in the presence of FACTS and a power system stabilizer (PSS) was studied under a diverse range of operating conditions. The coordinated tuning of SVC and PSS parameters as well as a TCSC in the presence of a wind energy conversion system was analyzed. The salp swarm algorithm, a recently developed meta-heuristic approach, was used for tuning TCSC, SVC, and PSS parameters. The supremacy of TCSC over SVC for improving system stability was demonstrated under a diverse range of operating conditions.

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