Exposure to extreme weather conditions increases power systems’ vulnerability in front of high impact, low probability contingency occurrence. In the post-restructuring years, due to the increasing demand for energy, competition between electricity market players and increasing penetration of renewable resources, the provision of effective resiliency-based approaches has received more attention. In this paper, as the major contribution to current literature, a novel approach is proposed for resiliency improvement in a way that enables power system planners to manage several resilience metrics efficiently in a bi-objective optimization planning model simultaneously. For demonstration purposes, the proposed method is applied for optimal placement of the thyristor controlled series compensator (TCSC). Improvement of all considered resilience metrics regardless of their amount in a multi-criteria decision-making framework is novel in comparison to the other previous TCSC placement approaches. Without loss of generality, the developed resiliency improvement approach is applicable in any power system planning and operation problem. The simulation results on IEEE 30-bus and 118-bus test systems confirm the practicality and effectiveness of the developed approach. Simulation results show that by considering resilience metrics, the performance index, importance of curtailed consumers, congestion management cost, number of curtailed consumers, and amount of load loss are improved by 0.63%, 43.52%, 65.19%, 85.93%, and 85.94%, respectively.

Due to the utilization of fundamental frequency, current impedance-based fault location methods are able to locate only permanent and linear faults. The duration of the arc in low and medium voltage systems can be as short as a quarter of a cycle. This period, which is normal for intermittent faults, is insufficient for fundamental frequency-based fault location algorithms. Therefore, available methods are not applicable for intermittent arcing fault location. In this paper, the time-based method previously proposed by the authors has been developed to locate short duration faults in LV distribution systems. The advantage of the proposed method over available methods is its capability for locating faults using fewer samples, which enable the user to locate both arcing faults as well as normal faults in the network. The main characteristics of an arcing fault, i.e., non-linearity and short duration, have been addressed in the proposed algorithms methodology. Various characteristics of a LV distribution system (i.e., heterogeneity, unbalanced load and line, etc.) have been taken into account in the current enhanced algorithm. The validity of the devised algorithm is studied within PSCAD-EMTDC environment and the obtained results show a good accuracy.

We propose novel techniques to find the optimal location, size, and power factor of distributed generation (DG) to achieve the maximum loss reduction for distribution networks. Determining the optimal DG location and size is achieved simultaneously using the energy loss curves technique for a pre-selected power factor that gives the best DG operation. Based on the network’s total load demand, four DG sizes are selected. They are used to form energy loss curves for each bus and then for determining the optimal DG options. The study shows that by defining the energy loss minimization as the objective function, the time-varying load demand significantly affects the sizing of DG resources in distribution networks, whereas consideration of power loss as the objective function leads to inconsistent interpretation of loss reduction and other calculations. The devised technique was tested on two test distribution systems of varying size and complexity and validated by comparison with the exhaustive iterative method (EIM) and recently published results. Results showed that the proposed technique can provide an optimal solution with less computation.

This paper presents and discusses results of analysis from investigations of arc-to-glow transformation phenomenon at contact opening, under dc low-energy (≤10 J) and low-voltage (≤250 V) inductive loads. Dependence of the duration of arcing and glowing on current magnitude, voltage magnitude, properties of the contact material, gas quenching medium velocity and its pressure, as well as contact opening velocity and contact gap are investigated. The transition phenomenon of arc-to-glow is analyzed by means of fast photography and emission spectroscopy. Also discussed is the theoretical evaluation of conditions of arc instability. From the results, possible procedures are formulated to control the arc-to-glow transformation for practical use in dc low-voltage and low-power electrical grids.

Laryngeal schwannomas are rare benign encapsulated neurogenic tumors that represent less than 1.5% of all benign laryngeal tumors. We report a case of voluminous laryngeal schwannoma that was incidentally found during endotracheal intubation for thyroidectomy in a 43-year-old woman with clinical findings, features of radiologic and histopathologic examinations. The tumor was removed by CO₂ laser during microlaryngoscopy. In this case report, we present a challenging approach that can be used in diagnosis and treatment of laryngeal schwannomas. Complete removal of the tumor should be considered as the initial approach to minimize morbidity.