After a permanent fault occurs if it is not possible to supply the load in the network, the optimal load restoration scheme allows the system to restoration the load with the lowest exit cost, the lowest load interruption, and in the shortest possible time. This article introduces a new design called Smart Load SHEDDING, abbreviated SLS. In the proposed SLS scheme, the types of devices in smart homes are divided into four categories: adjustable, interruptible, shiftable, and uncontrollable loads. In this design, a new two-layer algorithm is proposed to solve the service restoration problem. In the first layer, a heuristic method based on graph theory for optimal system configuration is presented. In the second layer, for optimal load restoration, tools such as rescheduling of distributed GENERATION sources, load SHEDDING, load curtailment, and sensitive load curtailment are used. This layer is a nonlinear mixed-integer nonlinear programming problem. To achieve the optimal global solution and less solution time, the model changes from nonlinear programming of non-convex mixed integer nonlinear programming to mixed-integer linear programming. A modified RBTS distribution system is used as a test system to demonstrate the effectiveness of the proposed method.

According to extent of electrical distribution system, always probabilities of severe disturbances are available and this system may experience emergency condition in witch some of variables such as grid frequency, voltage, equipment limits, and etc. may be violated. To control and alleviate the problem and also prevent of electrical distribution system instability (that finally led to system black out), the control (dispatching) center may using "Load SHEDDING and GENERATION Reallocation (LSGR)" terms.But an important question here is: "how much is the optimum amount of load SHEDDING and also GENERATION reallocation to retrieval the power system to normal condition?" For answering above question, based on one of the strongest mathematical method (Non linear programming), an effective LSGR optimization problem is proposed in this thesis. In this mathematical optimization problem (Non linear programming) the objective function consists of "load curtailment" and "powerplant reallocation" terms as decision making variables. Beside various constraints like equipment capabilities, voltage magnitudes, frequency limitation and load flow equations, the load dependency of voltage and frequency is considered. Following, an algorithm is designed and proposed for getting the best result/conclusion of LSGR optimization problem. Finally the developed algorithm are tested on typical power system. the result achieved proved that the technique are highly capable of relieving emergency conditions. 

Transient instability, voltage instability or a combination of both have been the cause of several power system blackouts all over the world in the recent years. Occurrence of a super-component contingency (SCC) that refers to multiple and simultaneous outages of grid facilities like a power plant or a multi-circuits line may lead to blackout if no remedial action schemes (RAS) are implemented. This paper proposes a new event-based RAS to overcome the transient and voltage instabilities caused by super-component contingencies through optimal GENERATION SHEDDING and load cut. To do this, a new multi objective framework is presented simultaneously optimizing the competing objective functions of transient and voltage stability margins and GENERATION shed and load cut amount. Multi objective decision making is performed using a combination of analytical hierarchy process (AHP), modified augmented e constraint method and technique for order preference by similarity to ideal solution (TOPSIS). The effectiveness of both the proposed model and MODM solution approach is extensively illustrated on a simulated model of Iran’s power system in 2014.

The unstable flow with rotating-stall-like (RS) effects in a rotor-cascade of an axial compressor was numerically investigated. The RS was captured with the reduction in mass flow rate and increasing of exit static pressure with respect to design operating condition of the single rotor. The oscillatory velocity traces during the stall propagation showed that the RS vortices repeat periodically, and the mass flow rate was highly affected by the blockage areas made by stall vortices. The results also showed that large scale vortices highly affects on the GENERATION and growth of the new vortices. An unsteady two-dimensional finite-volume solver was employed for the numerical study which was developed based on Van Leer’s flux splitting algorithm in conjunction with TVD limiters and the κ-ε turbulence model was also employed. The good agreement of the computed mass flow rate with the experimental results validates the numerical study.

In this study, the cylinder drag coefficient is reduced by using passive flow control. Installing a flat plate in two heights and different longitudinal distances in upstream flow increases the upstream flow momentum of the cylinder, leading to the higher boundary layer flow resistance against adverse pressure gradient which delays the flow separation. The flow separation delay enhances the pressure on the cylinder downstream. Then, the net pressure on the cylinder in the flow direction and, consequently, the cylinder drag coefficient are decreased. In case that the higher flat plate is utilized, the pressure on the upstream side is reduced more, leading to lower drag coefficient. However, for both heights of the flat plate at specific longitudinal distances from the cylinder due to the cavity flow formation between the cylinder and the flat plat, the vortex SHEDDING is suppressed and the cylinder upstream is changed from the pressure side to suction side, leading to lower net pressure on the cylinder in the flow direction and as a result, less drag coefficient. At the optimal flat plate configuration at and , the minimum cylinder drag coefficient reached 90% reduction in comparison to the single cylinder case in the same flow condition. Results show that the drag coefficient reduction behavior is similar for different sub-critical Reynolds numbers due to the constant flow pattern and no considerable variation of the separation point. The entropy GENERATION for the single cylinder and the case where the flat plate is located in its optimal configuration were investigated. The single cylinder has the highest entropy value, while the entropy of the optimal flat plate configuration with the cylinder reaches the lowest value, the same as the drag coefficient. Then, the drag coefficient is reduced by decreasing entropy GENERATION, indicating the direct relation between drag coefficient and entropy GENERATION.

This paper presents a reliability assessment algorithm for radial distribution systems such as microgrids and distributed GENERATION units. The effects of these units and system reconfigurations on distribution system reliability can be evaluated by using the proposed algorithm. The impacts of the location and capacity of the distributed energy resources of microgrids and sectionalizing switches on reliability indices are determined. Moreover, proper location is determined by the classification of load points in distribution system. An approach to identifying the out of the service section after a fault event is presented based on the adjacency matrices. The classification of nodes is obtained by identifying different adjacency matrices based on protective devices. At last, the reliability indices of radial distribution system are calculated.