• Transactions on Electrical and Electronic Materials
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• v.18 no.5
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• pp.287-297
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• 2017

Novel power system stabilizers (PSSs) have been proposed to effectively dampen low frequency oscillations (LFOs) in multi-machine power systems and have attracted increasing research interest in recent years. Due to this attention, recently, fractional order controllers (FOCs) have found new applications in power system stability issues. Here, a tilt-integral-derivative power system stabilizer (TID-PSS) is proposed to enhance the dynamic stability of a multi-machine power system by providing additional damping to the LFOs. The TID is an extended version of the classical proportional-integral-derivative (PID) applying fractional calculus. The design of the proposed three-parameter tunable TID-PSS is systematized as a nonlinear time domain optimization problem in which the tunable parameters are adjusted concurrently using a modified group search optimization (MGSO) algorithm. An integral of the time multiplied squared error (ITSE) performance index is considered as the objective function. The proposed stabilizer is simulated in the MATLAB/SIMULINK environment using the FOMCON toolbox and the dynamic performance is evaluated on a 3-machine 6-bus power system. The TID-PSS is compared with both classical PID-PSS (PID-PSS) and conventional PSS (CPSS) using eigenvalue analysis and time domain simulations. Sensitivity analyses are performed to assess the robustness of the proposed controller against large changes in system loading conditions and parameters. The results indicate that the proposed TID-PSS provides the better dynamic performance and robustness compared with the PID-PSS and CPSS.

• CELLMED
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• v.11 no.4
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• pp.19.1-19.8
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• 2021

Background: Dysmenorrhea is the most common menstrual complaint in young women with a prevalence as high as 90% and is responsible for substantial repeated short-term absenteeism from school and work in young women. The objective of this study was to compare the efficacy of Commiphora myrrha and honey with mefenamic acid in primary dysmenorrhea. Materials and Methods: This prospective standard controlled trial was conducted at Luqman Unani Medical College Hospital and Research Center Vijayapura, India where 40 diagnosed patients of primary dysmenorrhea were randomly assigned to receive test drug (powdered Commiphora myrrha gum resin10g with 30g honey in two divided doses) or active control drug (mefenamic acid 250mg TID) for first 3days of menstruationfor two consecutive cycles. The primary outcome measure was reduction in severity of pain assessed by numerical pain rating scale (NPRS), and secondary outcome measures were improvement in quality of life (QOL) assessed by SF-36 and reduction in perceived stress score (PSS). Results: During first cycle treatment no significant difference was found in NPRS score (p=0.085) between the groups however significant difference in NPRS score (p<0.001) was seen during 2^nd treatment cycle. Significant reduction (p=0.022) in the perceived stress score was noted and overall quality of life was markedly improved after treatment in both the groups. Conclusion: These data suggest that Commiphora myrrha gum resin with honey is an effective herb in reducing symptoms of primary dysmenorrhea. These results need to be confirmed by a properly designed trial with a larger sample size. Trial registration: Clinical Trial Registry India CTRI/2017/09/009596.