The application of directional overcurrent relays (DOCRs) plays an important role in protecting power systems and ensuring their safe, reliable, and efficient operation. However, coordinating DOCRs involves solving a highly constrained and nonlinear optimization problem. The primary objective of optimization is to minimize the total operating time of DOCRs by determining the optimal values for decision variables such as the time multiplier setting (TMS) and plug setting (PS). This article presents an efficient hybrid optimization algorithm that combines the modified firefly algorithm and genetic algorithm to achieve improved solutions. First, this study modifies the firefly algorithm to obtain a global solution by updating the firefly’s brightness and to prevent the distance between the individual fireflies from being too far. Additionally, the randomized movements are controlled to produce a high convergence rate. Second, the optimization problem is solved using the genetic algorithm. Finally, the solution obtained from the modified firefly algorithm is used as the initial population for the genetic algorithm. The proposed algorithms have been tested on the IEEE 3-bus, 8-bus, 9-bus and 15-bus networks. The results indicate the effectiveness and superiority of the proposed algorithms in minimizing the total operating time of DOCRs compared with other optimization methods presented in the literature.

This paper provides a comprehensive review of optimization techniques for coordinating directional overcurrent relays in power systems. It covers a wide range of techniques, including conventional and deterministic methods, metaheuristic algorithms, and hybrid approaches. The paper discusses the objective functions utilized in formulating relay coordination problem and presents the development of optimization methods for solving this problem. Furthermore, it examines the criteria for comparing different algorithms for coordination problem and includes a case study to demonstrate the practical application of these criteria. It also presents simulation software employed for examining and validating results obtained from optimization algorithms. Future trends and challenges regarding optimal coordination of directional overcurrent relays are also discussed. The paper concludes that there is no single "best" optimization technique for the coordination problem. The best technique for a particular application will depend on the specific characteristics of the power system and the constraints of the coordination problem.

This study is relevant to the efforts being made to support the Libyan state achieve its goal of reducing greenhouse gas emissions since Libya is one of the countries that ratified the Paris Agreement of 2015 and participated in the COP27 conference. Therefore, this research aims to estimate the amounts of Co 2 emitted from Libyan power industry sector. The results presented in this research is based on real measured data that had been collected over long periods of time series by monitoring and control systems of the considered power plants. Thus, the presented here Co 2 emission factors on different basis can be considered as an indicator to the environmental situation of the power industry sector of Libyan State. The methodology used in this study can be adopted to estimate other air pollutions emission factors in the power sector or even in other sectors. The results were also compared with emission inventories published by environmental agencies such as IPCC, EAA, EAI, and EEM, as well as the standards set by UNFCCC. This research sounds the alarm that the current environmental situation of the stations is much worse than all expectations, and therefore scientists and decision-makers must take immediate measures to reduce pollution in this sector.

Electric power transmission networks should be operated in efficient, safe, and reliable conditions. To improve the stability and transfer capability of power transmission, it is necessary to mitigate the Ferranti effect. This paper investigates the impact of increasing the length of the transmission line on its receiving end voltage under no-load conditions. A variable shunt reactor compensation for transmission lines is used to control the voltage level at different lengths of the transmission line. The proposed method demonstrates that the value of the shunt reactor required to maintain the receiving end voltage can be estimated. Moreover, the system is modeled using the PowerWorld simulator, and the effectiveness of the proposed model has been verified by experimental results. The experimental results demonstrate the efficiency of the proposed methodology and match the simulation results, which are then validated by simulating the WSCC 9-bus and IEEE 30-bus test systems.

Little works considered the optimization of working fluids in solar systems. Engineers, designers and scientists are interested with the optimization problems, furthermore it is very important specially, for solar systems to improve the energetic behavior and increase their efficiencies as a conversion system of solar irradiance to a useful thermal power. According to the available literature, the criteria of optimization mainly relates to energetic and economic analysis (one of them or both). The analysis was based upon the maximum useful energy obtained from solar collector. Accordingly, the optimum mass flow rate was found aspires to infinity. The second analysis is based upon minimum cost of the unit of useful energy [$/W]. The optimum mass flow rate of solar air-heating flat-plate collector for the considered domestic solar heating system has been found 29 kg/h per square meters of solar collectors. This paper deals with a third criteria that is, the amount of the additional energy required to achieve the required task from the solar system by means of auxiliary heating system. In where both the outlet temperature and mass flow rate play crucial role in the heat exchange between the fluid in the collector loop and the fluid in the load loop.