Sharif Digital Repository

Despite the need for change, highly available software systems cannot be stopped to perform changes because disruption in their services may consequent irrecoverable losses. Current work on runtime evolution are either too disruptive, e.g., "blackouts" in unnecessary components in the quiescence criterion approach or presume restrictive assumptions such as the "black-box design" in the tranquility approach. In this paper, an architecture-based approach, called SAFER, is proposed which provides a better timeliness by relaxing any precondition required to start reconfiguration. We demonstrate the validity of the SAFER through model checking and a realization of the approach on a component... 

Both frequency and intensity of natural disasters have intensified in recent years. It is, therefore, essential to design effective strategies to minimize their catastrophic consequences. Optimizing recovery tasks, including distribution system reconfiguration (DSR) and repair sequence optimization (RSO), are the key to enhance the agility of disaster recovery. This article aims to develop a resilience-oriented DSR and RSO optimization model and a mechanism to quantify the recovery agility. In doing so, a new metric is developed to quantify the recovery agility and to identify the optimal resilience enhancement strategies. The metric is defined as 'the number of recovered customers divided... 

This article indicates the accurate method for load level calculation to solve the power flow problem when capacitor reactive power is involved. Using the correct method causes some changes in the results and conclusion stated in the discussed paper on optimal reconfiguration and capacitor placement in radial distribution systems  

A significant share of losses in power systems occurs in distribution network due to lower voltages and longer lines. On top of that, unbalanced operation causes additional losses in these networks. In recent years with the development of distributed generation connected to the distribution grid, the concern over frequency and intensity of unbalanced operation has risen. Reconfiguration of these distribution networks plays a significant role in power loss minimization and voltage quality enhancement. The uncertainty regarding grid-connected DG resources and net loads are among the critical factors that must be taken into account. To do so, in this paper a novel Fuzzy-based reconfiguration... 

Distribution system reconfiguration is an effective solution to reduce the consequences of a disaster through transferring loads to another feeder via automatic switches. Meanwhile, an optimal sequence of damage components repairments provides the operator with the opportunity to utilize components that play a critical role in restoring loads sooner. Motivated by the rise in penetration of renewable distributed generators in modern distribution systems, this paper aims to develop a robust reconfiguration and crew routing co-optimization method to cope with renewable and demand uncertainties while recovering from a disaster. The method optimizes the grid recovery process for the worst... 

An adaptive approach for distribution system reconfiguration and charging management of plug-in electric vehicles (PEV) is presented in this study. A stochastic model predictive control is applied to stochastically, adaptively, and dynamically reconfigure the system, manage the incidental charging pattern of PEVs, and deal with the variable and uncertain power of renewable energy sources. The objective function of problem is minimizing daily operation cost of system. Herein, the geography of area is considered and the behavior of PEVs' drivers (based on their income level) is modeled with respect to the value of incentive and their hourly distance from each charging station. It is shown that... 

An adaptive approach for distribution system reconfiguration and charging management of plug-in electric vehicles (PEV) is presented in this study. A stochastic model predictive control is applied to stochastically, adaptively, and dynamically reconfigure the system, manage the incidental charging pattern of PEVs, and deal with the variable and uncertain power of renewable energy sources. The objective function of problem is minimizing daily operation cost of system. Herein, the geography of area is considered and the behavior of PEVs' drivers (based on their income level) is modeled with respect to the value of incentive and their hourly distance from each charging station. It is shown that... 

Nowadays, the essentiality of asset management in power systems and higher utilization of resources have become more critical to keep pace with the radically growing demand of today's networks. Power transformers are amongst the most important equipments installed in power distribution systems. Therefore, this paper presents a novel methodology to improve the utilization of substation transformers. In this methodology, the transformer utilization of a two-transformer substation is increased via reconfiguration considering the single contingency policy (SCP). The online reconfiguration helps to maximize the amount of load transferred from a substation with a failed transformer to its... 

This paper presents a reliability assessment algorithm for distribution systems using a Static Series Voltage Regulator (SSVR). Furthermore, this algorithm considers the effects of Distributed Generation (DG) units, alternative sources, system reconfiguration, load shedding and load adding on distribution system reliability indices. In this algorithm, load points are classified into 8 types and separated restoration times are considered for each class. Comparative studies are conducted to investigate the impacts of DG and alternative source unavailability on the distribution system reliability. For reliability assessment, the customer-oriented reliability indices such as SAIFI, SAIDI, CAIDI... 

Capacitor placement/setting is one of the main means for loss reduction and voltage profile improvement in distribution systems. If capacitor placement is meant, the objective function will be the cost of energy losses besides the capacitors costs in a specified period of time. Here, reconfiguration can be used as a strategy to reform the base configuration of the distribution network in order to place the capacitors more efficiently with lower costs. On the other hand, if capacitors are already available in a network, optimum capacitors setting and network reconfiguration should be performed for power loss minimization. In this paper both power loss minimization and capacitor placement cost...