Firefly algorithm scaled fractional order fuzzy PID based PSS for transient stability improvement

This paper presents an improvement in stability in a single machine connected to infinite bus power system by designing an optimal fractional order fuzzy PID based power system stabilizer (FOFPID-PSS). The low frequency oscillations resulting from load switching are damped out by the designed PSS under different operating conditions. In this paper, a bio-inspired algorithm called firefly algorithm (FA) has been employed for tuning the parameters of the proposed FOFPID-PSS controller. The robustness of the proposed controller is tested for enhancing the transient stability under different operating conditions like step and random variations in load demand. In addition to the graphical results, a comparative analysis of the proposed FOFPID-PSS controller with that of conventional PID-PSS and fuzzy PID-PSS (FPID-PSS) is also presented in terms of the performance indices (PIs) like maximum overshoot, settling time and integral squared error (ISE). The results suggest that the proposed FOFPID-PSS outperforms the FPID-PSS and PID-PSS controllers

A Hybrid Firefly-Swarm Optimized Fractional Order Interval Type-2 Fuzzy PID-PSS for Transient Stability Improvement

This article focuses on the implementation of a hybrid firefly algorithm-particle swarm optimization (FAPSO) scheme for optimizing the parameters of an interval type-2 fractional order fuzzy proportional integral derivative (IT2FOFPID)-based power system stabilizer (PSS) to minimize the low-frequency oscillations in a power system. Here, the IT2FOFPID-based PSS is designed by considering speed deviation and acceleration as input signals. In this article, a single machine infinite bus system and the New England 10 machine 39-bus power system are used for testing and comparing the approaches. Stability studies are also performed using OPAL-RT's OP5600, a real-time digital simulator. The comparative studies demonstrate that the hybrid FAPSO optimized IT2FOFPID-PSS provides better damping and stability performance when compared with the PSSs based on the FA/PSO/ hybrid genetic algorithm and bacterial foraging optimization and hybrid differential evolution and pattern search optimized IT2FOFPID approaches under various operating scenarios

Microstructural characterization of Co-based coating deposited by low power pulse laser cladding

<p>A detailed microstructural study of Stellite 6 coating deposited on a low carbon ferritic steel substrate using preplaced powder method and low power Nd:YAG pulse laser is performed. The grain structure and solidification texture of the coating are investigated by orientation imaging microscopy (OIM) and scanning electron microscopy. In addition, the effect of consecutive pulses on the microstructure of the coating is examined. The orientation relationship (OR) at coating/substrate interface and the solid state phase transformation in heat-affected zone are studied as well as the Vickers microhardness profile measurement in order to support the microstructural observations. An important conclusion is reached that the shape of solidification front during pulsed laser cladding is similar to the shape of solidification front during continuous cladding with a doubled laser beam scanning speed. Further, OIM reveals the Greninger-Troiano OR between the face centered cubic coating and bcc substrate grains. It is concluded that at the moment of solidification epitaxial growth of the grains in the coating occur on the austenitic grains of the substrate and that an austenite-ferrite transformation occurs in the heat-affected zone upon subsequent cooling.</p>

Corrosion Protection of Metal Alloys by Laser Cladding

This chapter looks at laser cladding (LC) processes to improve the corrosion resistance of metallic alloys. A detailed literature survey has shown that LC is a cost-effective method for protecting high-value components from corrosion and erosion attacks