In this paper, a novel risk-based, two-objective (technical and economical) optimal reactive Power dispatch method in a wind-integrated Power system is proposed which is more consistent with operational criteria.  The technical objective includes the minimization of the new voltage instability risk index. The economical objective includes cost minimization of reactive Power generation and active Power loss. The proposed voltage instability risk employs a hybrid possibilistic (Delphi-Fuzzy)-probabilistic approach that takes into consideration the operator’s experience, the wind speed and demand forecast uncertainties when quantifying the risk index. The decision variables are the reactive Power resources of the system. To solve the problem, the modified multi-objective particle swarm optimization algorithm with sine and cosine acceleration coefficients is utilized. The method is implemented on the modified IEEE 30-bus system. The proposed method is compared with those in the previously published literature, and the results confirm that the proposed risk index is better at estimating the voltage instability risk of the system, especially in cases with severe impact and low probability. In addition, according to the simulation results compared to typical security-based planning, the proposed risk-based planning may increase the security and economy of the system due to better utilization of system resources.

In traditional Adjustable Speed Drives (ASDs) voltage controller low Power factor and high-energy are some of the major drawbacks. These can be eliminated using Genetic Algorithm based PWM optimization. This Genetic Algorithm optimization eliminates the harmonics in the inverter output and provides Power factor close to unity. The increased use of Power electronics-based loads, (adjustable speed drives, switch mode Power supplies (SMPS), etc.) for improving system efficiency and controllability results in increase in the harmonic distortion levels in end use facilities and overall Power system. In this paper, the harmonic contents and distortion factor are less in the output of Genetic Algorithm optimized pulse width Modulated impedance source inverter when compared to standard PWM and random PWM based inverters. It is the most economic methodology to improve the Power quality of inverters.

There are relatively few literatures about Flexible AC Transmission Systems (FACTS) in reliability aspects, particularly in composite system reliability evaluation. Reliability of the Power system could be studied by some indices that help to compare Power system under different conditions from reliability point of view. The actual benefits of the FACTS can be quantitatively estimated using suitable models and techniques. Corrective control as an alternative for the system reinforcement is proposed in this paper as a suitable way to ease the challenges related to building new transmission lines or reconstruction of Power grid. Static Var Compensator (SVC) as a member of FACTS family has been used as corrective control. A test case with three scenarios is considered for comparing the effect of SVC on the reliability of the Power system. It will be seen that the correct SVC replacement has a great influence on the reliability indices of Power grid and losses could be diminished.

The aim of this paper is to investigate a novel approach for output feedback damping controller design of STATCOM in order to enhance the damping of Power system low frequency oscillations (LFO). The design of output feedback controller is considered as an optimization problem according with the time domain-based objective function which is solved by a honey bee mating optimization algorithm (HBMO) that has a strong ability to find the most optimistic results. The effectiveness of the proposed controller are tested and demonstrated through nonlinear time-domain simulation studies over a wide range of loading conditions. The simulation study shows that the designed controller by HBMO has a strong ability to damping of Power system low frequency oscillations. Moreover, the system performance analysis under different operating conditions show that the j based controller is superior to the C based controller.

Voltage stability may be improved by various control functions. In this paper, it is shown that how High Side Voltage Control (HIVC) may be employed for this purpose. Two test systems, namely a 22- bus and IEEE U8-bus systems are used to demonstrate the proposed tuning strategy for HSVC control parameters.

In this paper Power system stability enhancement through static synchronous compensator (STATCOM) based controller is investigated. The potential of the STATCOM supplementary controllers to enhance the dynamic stability is evaluated. The design problem of STATCOM based damping controller is formulated as an optimization problem according to the eigenvalue based objective function that is solved by a particle swarm optimization (PSO) algorithm. The controllers are tuned to simultaneously shift the lightly damped and un-damped electro-mechanical modes of machine to a prescribed zone in the s-plane. The results analysis reveals that the designed PSO based STATCOM damping controller has an excellent capability in damping the Power system low frequency oscillations and enhance greatly the dynamic stability of the Power system.

In this paper, a new approach for improving the linearity characteristics of GaN Power amplifiers is presented. The method is based on the injection of the second harmonic signal to the input of the Power amplifier through a forward path. The effect of the second harmonic injection on the linearity characteristics of the Power amplifier is studied using two-tone theory and simulations. An active three-port linearizing circuit with the ability to generate a second harmonic signal with adjustable amplitude and phase has been proposed to implement this method. Further, the paper method has been evaluated for improving the linearity of two 10-watt Power amplifiers with different nonlinear characteristics. As a concept, the proposed circuit is also fabricated and used for linearizing the GaN Power amplifier. It has been shown that by injecting the second harmonic signal and properly adjusting its amplitude and phase, in addition to improving the linearity characteristics, including third-order intermodulation (IMD3), adjacent channel Power ratio (ACPR), and AM-PM characteristic, the 1-dB compression point is also increased.