This paper presents a novel meta-heuristic approach based on the crow search algorithm (CSA) for solving the optimal reactive power dispatch (ORPD) problem. The ORPD is formulated as a nonlinear optimization problem designed to minimize power losses while satisfying the required constraints. The CSA is a recent efficient approach that depends on the intelligent behavior of crows. Nowadays, it has been used to solve many complex engineering optimization problems where it has proven its power and effectiveness. Motivated by the high ability in solving complex optimization problems and faster convergence of CSA, this paper proposes a novel approach to solve the ORPD problem. Furthermore, the settings of control variables such as generator terminal voltage, tap changer positions, and capacitor banks are determined to achieve the minimum total power loss while satisfying a set of nonlinear constraints. The accuracy and the performance of the proposed algorithm were performed and compared to other meta-heuristic algorithms reported in the literature. Several tests are applied on two standard test systems, including IEEE 14-bus and IEEE 30-bus as well as on the large-scale Tunisian 86-bus system. In addition, a sensitivity analysis has been performed to valid the performance of the CSA in solving the ORPD problem. We demonstrate that the proposed CSA provides a supremacy results and statistically significant in solving ORPD problems (for IEEE-14 bus $p<0.0006$ , for IEEE-30 bus $p<0.006$ , and for Tunisian 86-bus $p<0.0000001$ ).

Neutral grounding systems are a critical element in the power system reliability. Thus, a good choice of grounding modes has become a hot-button issue among the power supply. During a single-phase to ground fault, current flows from the transformer winding through the ground path and the neutral grounding system. The paper presents considerations on the problematic of the grounding system. The theoretical and simulations studies allowed the control of the neutral grounding to avoid the insulation deterioration or accidental grounds in the transformer winding and avoid the distribution of zero-sequence current. For that reason, the attention of research is moving to developing a mathematical model to study the impact of neutral grounding transformer, the fault resistance effect and the impact of the distance separating a fault point to the power generators. We performed case study IEEE-14 bus under MATLAB environment.

The main issues in security assessment are the fast identification of the set of critical contingencies and their evaluation related to the severity level. This paper presents a simple heuristic method that can identify each state of the system and classify the contingencies in order of severity. Considering the multiple faults which can affect the margin of security of electrical network, transient stability is analyzed for different load and generation conditions. The critical clearing time is calculated by using the numerical method. We performed the IEEE-14 bus system using the well-known software EUROSTAG.