In this study, a novel flower pollination algorithm (FPA) has been suggested for optimal tuning of P and PI controllers included in a variable speed drive VSD system control circuit. In addition to the manual tuning of controllers’ parameters, several optimization algorithms like GA, PSO, GWO have been used for controllers optimal tuning in different studies. In this study, the errors caused by grid side current harmonic distortion in the VSD system have been used depending on SPWM technique to generate switching signals for a four-quadrant chopper circuit that acts like a filter and compensates the harmonic content in the grid current and smooth ripples in both DC-link current and voltage. The studied drive system and control circuit have been modeled using Matlab/Simulink, then it was linked with the proposed algorithm and tested under different operation conditions. A hardware laboratory model has been built and tested in order to confirm the validity of this study. Comparing the proposed algorithm with other optimization algorithms shows that the suggested algorithm outperforms other algorithms in improving the time response of the VSD system, reducing total harmonic distortion THD of grid current, and reducing ripple factor PF.

An efficient scheduling reduces the time required to process the jobs, and energy management decreases the service cost as well as increases the lifetime of a battery. A balanced trade-off between the energy consumed and processing time gives an ideal objective for scheduling jobs in data centers and battery based devices. An online multiprocessor scheduling multiprocessor with bounded speed (MBS) is proposed in this paper. The objective of MBS is to minimize the importance-based flow time plus energy (IbFt+E), wherein the jobs arrive over time and the job’s sizes are known only at completion time. Every processor can execute at a different speed, to reduce the energy consumption. MBS is using the tradition power function and bounded speed model. The functioning of MBS is evaluated by utilizing potential function analysis against an offline adversary. For processors m ≥ 2, MBS is O(1)-competitive. The working of a set of jobs is simulated to compare MBS with the best known non-clairvoyant scheduling. The comparative analysis shows that the MBS outperforms other algorithms. The competitiveness of MBS is the least to date.

This paper presents the reconfiguration of control circuit designed to control four-quadrant chopper placed in the variable speed drive system (VSDS)'s DC-link. The purpose of this design is to reduce the overall total harmonic distortion THD% of input current, and the ripple factor (RF) of the DC-link current in this system. Both of Grey Wolf Algorithm (GWO) & Particle Swarm Optimization (PSO) have been used to get the optimal parameters of proportional integral PI and proportional integral differential with filter PIDN controllers. The variable speed drive system and the proposed filter have been modeled in integration with the suggested algorithms to determine the optimal values of the controllers' parameters. The grey wolf algorithm GWO outperformed the PSO algorithm in term of reaching the optimum parameters in less number of iterations in both dynamic and static work conditions. Also, the time response of the system with GWO is better than with PSO.

The increased use of nonlinear loads in power systems have caused problems with the quality of electrical power systems, which affects its performance. One of the most important nonlinear loads is variable speed drive systems (VSDS) which causes issues to the industrial plants power supply. In this article, the authors compare different control methods to apply the bias voltages required to operate transistors in the four-quadrant chopper which added to the dc- link of the variable-speed drive system in order to improve power quality, considering future micro-grid systems. A selection is then made of the appropriate one that improves power quality specifications. This article discusses the issues related to VSDS, such as total harmonic distortion factor THD%; the ripple factor of the DC current and voltage of the VSDS; and its harmful effects on the power system.