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

Improvement in power quality using hybrid power filters based on robust extended Kalman filter

This paper presents a Hybrid Active Filter (HAF) used in the distribution network and is required for compensating reactive power in the load end and mitigate harmonics for the improvement of power quality. The compensation process used in this paper reduces number of sensors and also reduces the complication and depends on source current extraction. Initially for extraction of reference currents from harmonics surrounded line current, the Proportional-Integral (PI) or Fuzzy Logic Controller (FLC) is used, which controls the dc-link voltage of the inverter. The HAPF is designed with the use of Voltage Source Inverter (VSI). In this paper, an innovative approach called robust extended Kalman filter (RECKF) is implemented for reference current estimation/calculation using model predictive current (MPC). This RECKF-MPC essentially requires less number of voltage sensors and also overcome the problems associated with PI controllers like gain tuning. The new RECKF with MPC is compared with conventional PI and FLC and observed to be providing better performance to improve the power quality