Sharif Digital Repository

To tackle the air pollution issues, Plug-in Hybrid Electric Vehicles (PHEVs) are proposed as an appropriate solution. Charging a large amount of PHEV batteries, if not controlled, would have negative impacts on the distribution system. The control process of charging of these vehicles can be centralized in parking lots that may provide a chance for better coordination than the individual charging in houses. In this paper, an optimization-based approach is proposed to determine the optimum PHEV parking capacities in candidate nodes of the distribution system. In so doing, a profile for charging and discharging of PHEVs is developed in order to flatten the network load profile. Then, this... 

With anticipated proliferation of electric vehicles and distributed generations in near future, dynamic thermal rating (DTR) as a tool for unlocking network capacities, is becoming critical for distribution network operators. DTR is gaining a great and still growing focus of attention in today's power industries. However, potential benefits of DTR, although have been envisioned to be significant, have not yet been studied quantitatively. This paper intends to comprehensively assess the potential impacts of DTR on the performance of a realistic Finnish distribution network. For doing so, first a step-by-step procedure is devised. Then, weather data and loading information of circuits in the... 

In many popular applications like peer-to-peer systems, large amounts of data are distributed among multiple sources. Analysis of this data and identifying clusters is challenging due to processing, storage, and transmission costs. In this paper, we propose GDCluster, a general fully decentralized clustering method, which is capable of clustering dynamic and distributed data sets. Nodes continuously cooperate through decentralized gossip-based communication to maintain summarized views of the data set. We customize GDCluster for execution of the partition-based and density-based clustering methods on the summarized views, and also offer enhancements to the basic algorithm. Coping with... 

In a distributed system, each solution for the problem of Byzantine agreement requires that some of the correct processes reach a common decision value from a set of proposed values while Byzantine processes may behave arbitrarily. While the problem has been widely studied in fully connected fixed networks, few studies have been carried out in the context of self-organizing mobile networks such as mobile ad hoc networks. We present a randomized consensus protocol with three additional modules for the case of dynamic networks: participant detectors, failure detectors and maintainer. We assume an asynchronous network with unknown participants where processes can be fixed or move continuously... 

This paper presents a novel profit-based model for multistage distribution network expansion planning. In the proposed model, some capabilities of the distribution automation system are considered to achieve a plan that is more compatible with the strategic plan towards a smart distribution grid. Moreover, a method for reliability evaluation of a distribution network in the planning studies is proposed. The objective function of the planning problem is the net present value of the company's profit. The problem is solved by employing the genetic algorithm approach as a promising technique in solving the mixed-integer nonlinear programming problem. The proposed method is evaluated on an... 

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... 

In this paper, a new method for designing procedure of Reward-Penalty Scheme (RPS) in distribution system is proposed. Being fair and adoptable in viewpoint of distribution companies (DisCos) are main superiorities of the proposed RPS. Established based on concept of the Yardstick theory, its application can ensure regulators that a perfect competition will be created between DisCos to improve the service reliability. Also, such a regulation scheme can be a key for power system decision makers in order to prevent the DisCos from decreasing service reliability. Aimed to reach a fair mechanism, the proposed RPS rewards/penalizes the DisCos only compared with the other ones owning similar... 

This study presents a passive model to detect islanding conditions of synchronous distributed generation resources in a distribution network or a microgrid. The proposed approach uses the classification and regression tree algorithm for distinguishing between islanding and non-islanding situations. It utilises the rate of change of frequency (ROCOF) and harmonic content of the equivalent reactance seen at the location of distributed generation as input features for decision tree construction. Indeed the thresholds of the proposed input features are extracted by the decision tree algorithm. The output if-then rules of the decision tree algorithm are then utilised to make a new relay logic for... 

Distribution automation (DA) application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. As a result, various automation schemes have been developed and introduced in different countries and by different venders. The impacts of implementing a specific automation scheme on reliability indices of a given distribution system can be different from other available automation schemes. For this reason, when comparing the available automation schemes with each other or with the other reliability improvement measures, it is necessary to perform a course of reliability... 

Semantic technology is widely used in distributed computational environments to increase interoperability and machine readability of information through giving semantics to the underlying information and resources. Semantic-awareness, distribution and interoperability of new generation of distributed systems demand an authorisation model and framework that satisfies essential authorisation requirements of such environments. In this study, the authors propose an authorisation model and framework based on multi-security-domain architecture for distributed semantic-aware environments. The proposed framework is founded based on the MA(DL)2 logic, which enables policy specification and inference... 

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... 

Distribution systems management is becoming an increasingly complicated issue due to the introduction of new technologies, new energy trading strategies, and new deregulated environment. In the new deregulated energy market and considering the incentives coming from the technical and economical fields, it is reasonable to consider Distributed Generation (DG) as a viable option to solve the lacking electric power supply problem. This paper presents a mathematical distribution system planning model considering three planning options to system expansion and to meet the load growth requirements with a reasonable price as well as the system power quality problems. DG is introduced as an... 

Distribution systems management is becoming an increasingly complicated issue due to the introduction of new technologies, new energy trading strategies and new deregulated environment. In the new deregulated energy market and considering the incentives coming from the technical and economical fields, it is reasonable to consider Distributed Generation (DG) as a viable option to solve the lacking electric power supply problem. This paper presents a mathematical distribution system planning model considering three planning options to system expansion and to meet the load growth requirements with a reasonable price as well as the system power quality problems. DG is introduced as an attractive... 

Increasing use of networks and their complexity make the task of security analysis more and more complicated. Accordingly, automatic verification approaches have received more attention recently. In this paper, we investigate applying of an actor-based language based on reactive objects for analyzing a network environment communicating via Transport Protocol Layer (TCP). The formal foundation of the language and available tools for model checking provide us with formal verification support. Having the model of a typical network including client and server, we show how an attacker may combine simple attacks to construct a complex multiphase attack. We use Rebeca language to model the network... 

As a part of the ongoing debate about competition in the electricity industry, regulators are increasingly considering performance-based regulation (PBR) as an alternative to improve the service quality. The fundamental principle behind PBR is that good performance should lead to higher profits, and poor performance should result in lower profits. A penalty-reward structure (PRS) in a PBR mechanism can enhance utility performance to align utility interests with customer's interests. During the implementation of PBR, regulators should spend or receive money to reward good performed utilities or penalised poor performed utilities, respectively. A technique is proposed, in this study, to not... 

This paper introduces a new framework included mathematical model and a new software package interfacing two powerful softwares (MATLAB and GAMS) for obtaining the optimal distributed generation (DG) capacity sizing and sitting investments with capability to simulate large distribution system planning. The proposed optimization model allows minimizing total system planning costs for DG investment, DG operation and maintenance, purchase of power by the distribution companies (DISCOs) from transmission companies (TRANSCOs) and system power losses. The proposed model provides not only the DG size and site but also the new market price as well. Three different cases depending on system... 

This paper presents a long-term dynamic multi-objective model for distributed generation investment. The proposed model optimizes three objectives, namely active losses, costs and environmental emissions and determines the optimal schemes of sizing, sitting of DG units and specially the dynamics of investment over the planning period. The Pareto optimal solutions of the problem are found using a GA algorithm and finally a fuzzy satisfying method is applied to select the optimal solution considering the desires of the planner. The solutions of Pareto optimal front are analyzed to extract general useful information for planners about the appropriate DG technologies and placement schemes. The... 

This paper studies the optimization of micro turbine application to meet the electrical, heating and cooling loads of a building by energy, economics and environmental analysis. In this study following three cases are considered: 1: A simple micro gas turbine to meet the electrical power of the building. 2: A simple micro gas turbine to meet the electrical power of the building as well as the power required by heat pump and mechanical refrigerator needed for heating, cooling and domestic hot water (DHW) systems. 3: A CHP micro gas turbine to meet the electrical power of the building as well as part of the power required by heat pump and mechanical refrigerator needed for heating, cooling and... 

Rebeca is an actor-based language with formal semantics which is suitable for modeling concurrent and distributed systems and protocols. Due to its object model, partial order and symmetry detection and reduction techniques can be efficiently applied to dynamic Rebeca models. We present two approaches for detecting symmetry in Rebeca models: One that detects symmetry in the topology of inter-connections among objects and another one which exploits specific data structures to reflect internal symmetry in the internal structure of an object. The former approach is novel in that it does not require any input from the modeler and can deal with the dynamic changes of topology. This approach is...