The 2022 United Nations Climate Change Conference (COP27) recommended that Egypt be converted to green energy, in addition to increasing the demand for annual energy consumption, which will lead to an increase in the use of renewable energy sources (RES) in Egypt. The Egyptian Ministry of Energy and Electricity plans to build RES (photovoltaic systems and wind farms) connected to the Egyptian power system (EPS). It is a defect to choose the position and size of the RES based on only power calculations because the RES is an intermittent source. This paper presents a modified analytical energy technique for locating RES in IEEE 33-bus and 69-bus distribution networks and a realistic 25-bus 500 kV EPS. An analytical multi-objective function has been developed to determine the optimal locations of DGs or RESs based on power losses and annual energy loss calculations of the system depending on weather conditions. The efficiency and feasibility of the proposed algorithm based on the IEEE 33-bus and 69-bus distribution networks and the realistic 25-bus 500 kV EPS have been tested and compared with PSO and GA. The impact of RESs on the performance of the 25-bus 500 kV EPS has been investigated based on annual energy losses and operation stability depending on weather conditions. The results showed that the proposed technique used these effective values to obtain optimal weather-adjusted locations. The optimal locations of PV systems or wind systems based on energy calculation improved the voltage profile better than power calculation by about 2%, and the annual energy losses decreased by about 7%. The performance of the 25-bus 500 kV EPS, due to the addition of RES, resulted in a decrease in the annual energy losses of 47% and an improvement in the voltage profile and system stability.

Large computational load is one of the key issues of an electrical power system security analysis. Currently, most of the researchers are trying to find out how to reduce the computational load. The contingency analysis is one of the most promising approaches for solving the problem. In fact, there are several ways to improve the effectiveness of the contingency analysis. The first way is to reduce the number of simulated situations via contingency searching or contingency screening. Another way is to increase the efficiency of power flow computations. This paper presents a novel recursion-based approach for solving the contingency analysis problem. The approach improves the effectiveness of the contingency analysis by the above-mentioned ways. It relies on a specific contingency sorting procedure based on the recursive call of the calculating procedure. The proposed approach has been tested on the 14-bus IEEE test system. The results obtained show almost a twofold increase in the computational efficiency in comparison with the conventional contingency sorting procedure.

This paper aims to introduce an effective method of making allowance for the potential impact of other transmission system operators (TSOs) or market players on the operation mode of a specific TSO in estimations referring to the full grid model based on the amount of real-time data sufficient to simulate a limited the interconnected power system (IPS) zone, yet not enough to update the full grid model. The preparation procedure of simulation of the equipotential grid model (EG) within the IPS based on the up-to-date computer technology is disclosed. The results of the EG-based emergency disturbance simulation in reference to the power system state estimation (SE) in real-time are more reliable in comparison with the results of other models. The EG application is more efficient in the procedure of analyzing the IPS tolerability against a specific number of potential faults and outages of individual components empowered by the most relevant calculations due to well-known software support.

Due to the increasing penetration level of microgrids (MGs), it becomes a critical issue for MGs to help sustaining power system stability. Therefore, this paper is aimed at investigating comparison between transient analysis AC and DC Microgrid connected to the grid in case of using Superconducting Fault current limiter (SFCL) at the connection point of Microgrid and grid. When the three-phase-to-ground fault is applied at connection point of Microgrid and grid, the SFCL minimized the oscillating currents and the active and reactive power of AC and DC microgrid to range 20-30%. The transient analysis of AC microgrid is better than DC microgrid except the values currents and the active and reactive power are very high during the fault. The time required to recover pre-fault values of AC microgrid (0.1 sec) is less than those time of DC microgrid (3 sec).

The contribution current of an inverter-interfaced distributed generator unit during a fault is one of the significant challenges for two modes: grid-connected and isolated AC microgrid. For this challenge, this article is aimed to study two methods of fault current calculation for two modes: grid-connected and isolated microgrids. These methods include a virtual equivalent impedance and a proposed method. The proposed method is a new technique for calculating the fault current contribution depending on the droop control of inverter-interfaced DG. The proposed method can control the contribution short-circuit current of DG within its limit (2 p.u.) where it is dependent on the voltage value of the DG bus to calculate the short circuit current of DG by using the control criterion. Static security risk and load shedding are calculated after fault clearance using an operation scenario in which the distribution system will be divided into small subsystems and is then grid-connected and isolated due to the removal of the faulted bus by protection devices. The proposed technique is applied to a standard IEEE 33-bus distribution network with five DGs. The results show that the contribution current of inverter-interfaced DG during the fault has more effects than the fault current of the nearest faulted bus to the DG bus. The proposed technique improves the calculated fault current value by about 30% for the grid-connected microgrid and by about 50% for the isolated microgrid from its value of the virtual impedance method. The static security risk is improved after load shedding. The static security risk improved by about 0.025%.