Sharif Digital Repository

Presence of microgrids (MGs) and renewable energy sources (RESs) in distribution power systems could result in dramatic changes in operation and planning of these systems. In this regard, operational procedures employed by utilities should take into account the intermittent nature of RESs, while coping with the independent operation of MGs. In this perspective, this paper develops a distributed power management framework based on alternating direction method of multipliers (ADMM) for distribution networks with multi-MG (MMG) structures. The proposed approach develops a transactive signal in the context of ADMM to coordinate operation of MGs in a distributed manner. In this context, the... 

Million miles of gravity-fed drinking water and sewage pipelines around the world, especially in rural and urban areas in mountain ranges, have introduced a new renewable energy sources (RES), i.e., in-pipe hydropower systems (IHS). Output power of this technology, similar to other types of RES, suffers from intermittency, while it is still more predictable in comparison to other technologies of RESs. Besides, energy storage systems (ESS) are introduced as a pivotal technology for dealing with the intermittent and non-dispatchable characteristics of IHS through spatio-temporal arbitrage. This paper aims to develop a stochastic mixed-integer linear programming (MILP) formulation that... 

This paper introduces a day-ahead clearing model for the simultaneous energy and ancillary services market in high penetration of renewable energy sources (RESs) considering fast-start generators’ behaviors as non-spinning reserve providers. For managing the uncertainties of RESs, the system operator takes the advantages of the stochastic model of security-constrained unit commitment (SCUC) problem considering plausible scenarios. The non-convexities due to the startup costs, minimum power outputs, and commitment variables make the stochastic SCUC problem and market-clearing non-convex. Meanwhile, with traditional market-clearing methods for energy and ancillary services based on marginal... 

In order to attain an efficient path into the enhancement of the sustainable conservation and management of energy resources in the buildings and residential sections, efforts by all relevant institutions in the area of energy are essential and primitive. Hence, the development of the energy supply model in the building and the provision of fundamental solutions in this area is rudimentary. The key to any program related to this matter is to boost and extend energy efficiency and energy resource management. According to the global statistics and processed data, the residential sector accounts for 34 percent of the total energy consumption in Iran, which is the highest energy consumption... 

Water crisis is one of the main global risks that has different impacts on the society. This work uses available data and tools to track water storage changes in Iran, where lack of observations limits hydroclimatological studies and thus causes disasters. Data from Global Land Data Assimilation System (GLDAS) and Gravity Recovery and Climate Experiment (GRACE) are combined to analyze water storage changes (LWE) in Iran. GRACE signals indicate a large reduction of the water storage in North of Iran along the coast of the Caspian Sea (the largest global inland water body), where the water level has been oscillating significantly. In addition, results show the largest reduction of the water... 

Increasing penetration of renewable energy sources with intermittent generation calls for further flexibility requirements for efficient as well as the safe operation of power systems. Considering the significant growth of distributed energy resources in distribution systems, a promising approach to fulfill such requirements is to deploy local flexibility sources at the distribution level. Nonetheless, due to the monopoly nature of electricity distribution business, effective regulations are required to direct distribution companies toward fulfilling such goals. Accordingly, this paper aims at proposing various policies to motivate distribution companies to enhance the flexibility of their... 

Limited access to energy resources and increasing demand for mitigation of the environmental impacts have necessitated higher production efficiencies. Therefore, the promotion of R&D activities has been one of the main parts of national energy policies. In this research work, two methods are used for assessing the effectiveness of the R&D capital on resource conservation. First, by developing the resource-included knowledge production function of the energy sector and second, through direct assessment of the functionality of resource productivity from R&D capital. Based on official data provided by national statistical centers, a comparative analysis has been conducted to examine the... 

In this paper, the problem of frequency-constrained electricity market (FCEM) is modeled in the presence of renewable energy sources (RESs) and price-maker players by using equilibrium problem with equilibrium constraints formulation. It is worth mentioning that due to the intermittency of RESs, the FCEM problem in the presence of price-maker players becomes more imperative as stability of power system frequency is a public good and the free-rider problem arises. Moreover, as players of FCEM do not know their rivals' objective functions, the problem is modeled based on Bayesian game theory. The FCEM problem is converted into a game of complete but imperfect information under the common prior... 

In this paper, a hierarchical frequency regulation system is presented for real-time operation of the electrical grids. It includes a decentralized transactive energy system for clearing transactions of producers/consumers in real-time. The proposed system is implemented in a distributed fashion with small data communication requirement. It is proved that the proposed transactive energy system converges to the optimal power flow (OPF). An iterative method for optimizing control parameters of the proposed hierarchical frequency regulation system is also given. The proposed method is developed for high penetration of renewable energy sources (RESs) as the sizes, locations, and uncertainties of... 

Energy innovation is a key requirement to limit global warming and tackle climate change in the years to come. A better understanding of the public R&D mechanism is likely to improve allocation of resources for energy innovation. Thus, the present paper evaluates the impacts of public R&D and knowledge spillovers on the development of renewable energy sources. To achieve this goal, knowledge flow has been modeled as a function of public R&D expenditures, cumulative knowledge stocks and knowledge spillovers. To show the application of the model, the Nordic countries as one of the pioneers in renewable technologies have been chosen. Results show the cumulative knowledge stock will increase to... 

In this study, optimal offering strategy problem of a virtual power plant (VPP) as a price-maker player in day-ahead frequency constrained electricity market is presented. The optimal offering strategy problem is modelled as a bi-level optimisation problem. In the upper-level problem, the total profit of VPP is maximised. In the lower-level problem, the clearing conditions of frequency constrained electricity market are modelled. The proposed bi-level optimisation problem is reformulated as a mathematical programming with equilibrium constraints (MPEC) problem by using Karush-Kuhn-Tucker conditions. Then, the proposed MPEC problem, which is non-linear and hard to solve by commercial solvers,... 

With the increasing popularity of cloud computing services, the more number of cloud data centers are constructed over the globe. This makes the power consumption of cloud data center elements as a big challenge. Hereby, several software and hardware approaches have been proposed to handle this issue. However, this problem has not been optimally solved yet. In this paper, we propose an online cloud resource management with live migration of virtual machines (VMs) to reduce power consumption. To do so, a prediction-based and power-aware virtual machine allocation algorithm is proposed. Also, we present a three-tier framework for energy-efficient resource management in cloud data centers.... 

In this paper, Stochastic Activity Networks (SANs) are used to model and evaluate the performance and power consumption of an Infrastructure-as-a-Service (IaaS) cloud. The proposed SAN model is scalable and flexible, yet encompasses some details of an IaaS cloud, such as Virtual Machine (VM) provisioning, VM multiplexing, and failure/repair behavior of VMs. Using the proposed SAN, a power-aware self-adaptive resource management scheme is presented for IaaS clouds that automatically adjusts the number of powered-on Physical Machines (PMs) regarding variable workloads in different time intervals. The proposed scheme respects user-oriented metrics by avoiding Service Level Agreement (SLA)... 

Providing backhaul connectivity for macro and pico base stations (BSs) constitutes a significant share of infrastructure costs in future heterogeneous networks (HetNets). To address this issue, the emerging idea of flexible backhaul is proposed. Under this architecture, not all the pico BSs are connected to the backhaul, resulting in a significant reduction in the infrastructure costs. In this regard, pico BSs without backhaul connectivity need to communicate with their nearby BSs in order to have indirect accessibility to the backhaul. This makes the radio resource management (RRM) in such networks more complex and challenging. In this paper, we address the problem of cross-layer RRM in... 

In future wireless networks, network functions virtualization lays the foundations for establishing a new dynamic resource management framework to efficiently utilize network resources. In this paper, a network service can be viewed as a chain of virtual network functions (VNFs), called a service function chain (SFC), served via placement, admission control (AC), and embedding into network infrastructure, based on the resource management objectives and the state of network. To fully exploit such a potential and reach higher network performance, resource management stages should be jointly performed. To this end, two main challenges are: how to present a system model that formulates the... 

Network virtualization is a promising approach in which common physical resources are shared between service providers. Due to the substrate network limitations such as maximum available memory of each node of the substrate network as well as different service priorities and requirements, resource management in this setup is essential. On the other hand, SDN is bringing a considerable flexibility in resource management by introducing a centralized controller which can monitor all the substrate network states. In this paper, we propose a proactive admission control and dynamic resource management in SDN-based virtualized network in which the number of accepted high-priority virtual network... 

Despite advancements in developing physics-based formulations to estimate the sheet-flow travel time (tSHF), the quantification of the relative impacts of influential parameters on tSHF has not previously been considered. In this study, a brief review of the physics-based formulations to estimate tSHF including kinematic wave (K-W) theory in combination with Manning's roughness (K-M) and with Darcy-Weisbach friction formula (K-D) over single and multiple planes is provided. Then, the relative significance of input parameters to the developed approaches is quantified by a density-based global sensitivity analysis (GSA). The performance of K-M considering zero-upstream and uniform flow depth... 

The cloud manufacturing paradigm has been known as one of the best solutions for today's competitive manufacturing environments. This paradigm insists on using a manufacturing service oriented approach for fulfilling the manufacturing enterprise resource management by the access to global availability of manufacturing services. The proposed service oriented approach covers a wide area of manufacturing resource management from infrastructures to platforms and applications. However, due to wide global distributions of manufacturing clouds, the service oriented architectures which are designed in the clouds cannot communicate with each other. This is mainly due to concentration of cloud... 

Small islands around the world face various hazards such as sea-water level rise, hurricanes, human activities over pressure, environmental degradation, and pollution. Resiliency is a critical feature that has to be maintained in these sensitive and vulnerable areas. This paper focuses on the importance of Integrated Coastal Management (ICM) in increasing the level of resiliency in small islands. Integrated Coastal Zone Management (ICZM) has been recommended for practice by United Nations 1992 Rio Conference resolution to conserve the valuable natural resources of the coastal areas around the globe and improve their deteriorating environmental conditions. Integrated coastal management plan... 

One of the main advantages of utilizing flexible backhaul in future HetNets is that it can provide better user experience through flexible resource allocation. For this purpose, it is important to provide the required quality of service (QoS) in such networks. In this paper, we consider the problem of cross-layer radio resource management in HetNets with flexible backhaul which guarantees minimum total transmit power of BSs as well as the average end-to-end data rate requirement of each data flow. The problem is formulated as a two-timescale stochastic optimisation, where the long-timescale control variables are flow control, routing control and interference mitigation, while the...