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Abstract Reactive power dispatch is a vital problem in the operation, planning and control of power system for obtaining a fixed economic load expedition. An optimal dispatch reduces the grid congestion through the minimization of the active power loss. This strategy involves adjusting the transformer tap settings, generator voltages and reactive power sources, such as flexible alternating current transmission systems (FACTS). The optimal dispatch improves the system security, voltage profile, power transfer capability and overall network efficiency. In the present work, a fractional evolutionary approach achieves the desired objectives of reactive power planning by incorporating FACTS devices. Two compensation arrangements are possible: the shunt type compensation, through Static Var compensator (SVC) and the series compensation through the Thyristor controlled series compensator (TCSC). The fractional order Darwinian Particle Swarm Optimization (FO-DPSO) is implemented on the standard IEEE 30, IEEE 57 and IEEE 118 bus test systems. The power flow analysis is used for determining the location of TCSC, while the voltage collapse proximity indication (VCPI) method identifies the location of the SVC. The superiority of the FO-DPSO is demonstrated by comparing the results with those obtained by other techniques in terms of measure of central tendency, variation indices and time complexity.

With the development of urban and rural infrastructure, the power system is enforced to operate nearly at its full capacity which result in heavily stressed power grid operation, greater loss, peak generation, security threat and instability of the electrical network. The performance of the legacy electric network can be enhanced by solving optimal reactive power dispatch (ORPD) problems such as, tuning of the grid voltages, transformers tap setting, capacitor bank rating, allocation and sizing of flexible AC transmission system (FACTS) through computational intelligence tools. In last few decades, several optimization strategies are developed to solve ORPD problems but still research is in progress to leverage the performance of power system. In this line of thought, this paper provides a comprehensive literature of major optimization tools designed for the solution of ORPD problems with aim of improving the power system performance. The purpose of this study is to document up to date information on the optimal reactive power dispatch (ORPD), ORPD incorporating FACTS, mathematical model of ORPD problems with corresponding constraints, mathematical model of FACTS in ORPD, and applications of ORPD. At the end, a new computational tool based on fractional calculus has also been introduced for performance improvement of traditional swarming techniques to support researchers in field of energy/power sector and carry out further research.

Optimal reactive power dispatch (ORPD) problems in power system have been solved by using several variants of traditional nature inspired particle swam optimization (PSO) with aim to achieve a promising solution for a given objective such as line loss, voltage deviation and overall cost minimization. Several schemes have been designed to improve the performance of the optimization technique in tunning the operational variables and analyzed by evaluating the final results. In this article, a different method is designed to solve ORPD problems, by introducing Shannon entropy based diversity in the fractional order PSO dynamics, i.e., FOPSO-EE. The results show that synergy of both, the Shannon entropy and the fractional calculus can be used as the useful tools for enhancing the optimization strength of algorithm while solving the ORPD problems in standard IEEE 30 and 57 bus power systems. The performance of the design FOPSO-EE is further validated through results of statistical interpretations in terms of histogram analysis, box plot illustration, quantile-quantile probability plot and empirical probability distribution function.

FSOL (Free-Space Optical Links) are becoming very popular due to the inherent advantages of high data rates, rapid deployment, portability, cost effective and immunity to electromagnetic interference. FSOL is a line-of-sight technology that uses a modulated beam of light to transmit and receive the data of multiple of Giga Bit per second. FSOL uses the free space or atmosphere as a communication channel. Optical signal launched at transmitter end, travels through the atmosphere and reaches to the receiver, is severely affected by the local atmospheric conditions. Atmosphere contains different atmospheric particulates like fog, rain, snow, smog, clouds and haze. These atmospheric particulates, particularly fog, effect the propagation of optical signal passing through the atmosphere and cause significant amount of optical attenuation. In order to deploy FSO system, a detailed analysis of local weather condition is much more important. Here, we present the measured visibility data for analysis of optical attenuation. Visibility data was measured at COMSATS Institute of Information Technology from 2009-2012. Percentage CDF (Cumulative Distribution Function) is used to find out the detailed insight about the optical attenuation of FSOL. Yearly based CDFs is compared with each other which clearly suggest that almost 99% of time optical attenuation remains within the range of 2 dB/km.