Sharif Digital Repository

Hardening and operational measures in electrical distribution systems (EDSs) aim at improving the resilience of EDS in case of natural disasters. This paper proposes a novel two-stage framework for establishing optimal restoration paths for supplying critical loads (CLs) in the aftermath of a natural disaster that will improve the resilience of EDSs. To this end, in the first stage, an algorithm is introduced to find all possible candidate paths between available distributed energy resources (DERs) and CLs, the output of which is applied to the second stage, as the inputs. Subsequently, in the second stage, the problem of finding the optimal restoration paths is modeled as a mixed integer... 

The continuous spread of distributed energy resources (DERs) such as combined heating and power (CHP), diesel generators, boilers and renewable energy sources provide an effective solution to energy related problems to serve the power and heat demands with minimum cost. Moreover, the DERs may play a significant role for supplying power and heat in rural areas, where grid electricity is not available. Also, some dry areas may face water scarcity and salinity problems. So, one important solution is the use of DERs to drive desalination units in order to solve water scarcity and salinity problems. In this study, the optimal scheduling of DERs and reverse osmosis (RO) desalination unit that feed... 

In this paper, the operation of a future distribution network is discussed under the assumption of a multi-carrier microgrid (MCMG) concept. The new model considers a modern energy management technique in electricity and natural gas networks based on a novel demand side management (DSM) which the energy tariff for responsive loads are correlated to the energy input of the network and changes instantly. The economic operation of MCMG is formulated as an optimization problem. In conventional studies, energy consumption is optimized from the perspective of each infrastructure user without considering the interactions. Here, the interaction of energy system infrastructures is considered in the... 

Virtual power plant (VPP) aggregates the capacity of diverse distributed energy resources (DERs) dispersed around the network and creates an individual operating portfolio from the composition of DERs characteristics. VPP can schedule the DERs to provide energy and different types of reserve services in order to trade in wholesale electricity markets or provide network services. In this chapter, an optimization model of VPP to provide energy and reserve is addressed. In this regard, diverse DERs’ energy and reserve models are mentioned and optimization models of VPP to aggregate DERs in order to provide energy and reserve and make profit in wholesale markets are regarded. Furthermore, a... 

Virtual power plant (VPP) aggregates the capacity of diverse distributed energy resources (DERs) dispersed around the network and creates an individual operating portfolio from the composition of DERs characteristics. VPP can schedule the DERs to provide energy and different types of reserve services in order to trade in wholesale electricity markets or provide network services. In this chapter, an optimization model of VPP to provide energy and reserve is addressed. In this regard, diverse DERs' energy and reserve models are mentioned and optimization models of VPP to aggregate DERs in order to provide energy and reserve and make profit in wholesale markets are regarded. Furthermore, a... 

This paper investigates the performance of a smart distribution system comprised of multi-microgrids during emergency conditions. It also proposes a hierarchical scheme for outage management in such a system to enhance the security of supply during contingencies. This goal is achieved through sharing the available generation and storage capacities among different microgrids. In this regard, at first, a well-organized framework is devised in order to introduce the roles and tasks of each player in operation stage of a multi-microgrids system. Based on this framework, the general optimization model that needs to be evaluated in the proposed outage management scheme is formulated. Then, various... 

This paper presents a new robust co-planning model for transmission investment and merchant distributed energy resources (DERs). The problem is formulated from the viewpoint of power system regulators and planners such that they will build the new transmission facilities and identify optimal locations to direct merchant DERs. The proposed model is a tri-level min-max-min optimization problem where the upper, middle, and lower levels are investment decision of transmission lines and DERs, worst case realization of uncertain parameters, and the best actions in order to minimize the operation costs. The model considers the uncertainties associated with future peak load and generation capacity,... 

Increasing the integration of distributed energy resources (DERs) inspired by environmental and governmental incentives, beside the introduction of multi-agent structure perspective have led to a paradigm shift of operational conditions in distribution systems. In this context, the traditional concept of fit and forget in the distribution grid management would not be efficient in the modern distribution systems and consequently new mechanisms should be developed in order to enable the distribution system operator (DSO) to efficiently manage the grid congestion caused by peak power output of DERs or load demands requests. In this article, the Stackelberg game concept is employed to develop an... 

Load management and cost optimization are among the important factors in trigeneration systems and combined cooling, heating and power (CCHP) systems. In this study, an innovative CCHP system uses a gas turbine as the prime mover and has a heat recovery steam generator (HRSG) in addition to an auxiliary boiler, electric and absorption chillers. The system is tied with the bulk electric grid; to export and sell excess power or import power when necessary. This study analyzes load management and cost optimization of CCHP systems. A heuristic strategy to optimize the total energy cost is then presented. The optimal size of CCHP is determined from the study results. This paper proposes a model... 

The complex structure of the power system and the pivotal role of electrical energy in determining the socio-economic indicators of any countries lead the policy makers of power industry to take into account the expansion planning of generation system with high priority. Considering the intense fluctuations of costs in electrical energy generation (particularly due to variation of fuel prices within the recent years in the Middle East), finding an optimal generation portfolio, regardless of the costs variations risk looks impossible. The portfolio theory, as an efficient tool for risk management, provides a proper solution to materialize the optimal generation portfolios with the following... 

As the number of distributed energy resources (DERs) increases, so would their influences on the power systems. Toward managing the intermittent nature of DERs, and providing market participation capability, the concept of virtual power plant (VPP) has been developed in the smart grid era. This paper proposes a novel offering strategy method for a VPP consisting of wind power generation along with storage capacity and flexible demand. In the proposed method, two different sources of uncertainty are addressed: stochastic method, applied in dealing with market price uncertainty, and information-gap decision theory (IGDT), incorporated in the offering model counting for wind power production... 

Power systems are undergoing significant transformations due to the introduction of microgrids (MGs) and distributed energy resources (DERs). In this regard, MGs as new entities in the system facilitate the integration of independently operated DERs to the power system. In this structure, DERs would be operated by independent agents, while the microgrid's control unit (MCU) would coordinate agents' resource scheduling to maximize social welfare. In this structure, the uncertainty of resources operated by agents could lead to real-time energy imbalance in the MG resulting in agents' loss of profits. Consequently, a novel transactive-based-scheme is developed in this article to facilitate... 

The increasing integration of renewable energy resources (RERs) and the expansion of multi-microgrid systems have transformed the operational condition of power systems. Respectively, the high-amount installation of RERs could result in the volatile changes exchanged-power of local systems, when their power generation drops suddenly. Nevertheless, the available ramp-up power for compensating the supply-demand gap in the power system could be limited due to the operational constraints of power networks and generation units. As a result, in this article, a transactive flexible-ramp-up-management-mechanism is offered in order to enable system operators to exploit the scheduling of microgrid... 

This paper presents a new framework for island formation prior to windstorms, which considers tree-caused failures of distribution networks. In the proposed framework, both direct and indirect effects of windstorms on distribution lines are quantified. Thus, a novel discrete Markov chain model is proposed for representing the failure modes of trees in each time interval of windstorm duration. This model categorizes 'healthy', 'uprooted', 'stem breakage', and 'branch breakage' states of a tree. In addition, a new line-tree interaction model is presented for calculating tree-caused failure probability of overhead lines. The results of the proposed Markov model are taken as inputs by the... 

As a matter of course, the unprecedented ascending penetration of distributed energy resources, mainly harvesting renewable energies such as wind and solar, is concomitant with environmentally friendly concerns. This type of energy resources are innately uncertain and bring about more uncertainties in the power system context, consequently, necessitates probabilistic analysis of the system performance. Moreover, the uncertain parameters may have a considerable level of correlation to each other, in addition to their uncertainties. The two point estimation method (2PEM) is recognised as an appropriate probabilistic method. This study proposes a new methodology for probabilistic power flow... 

As energy resource planning associated with environmental consideration are getting more and more challenging all around the world, the penetration of distributed energy resources (DERs) mainly those harvesting renewable energies (REs) ascend with an unprecedented rate. This fact causes new uncertainties to the power system context; ergo, the uncertainty analysis of the system performance seems necessary. In general, uncertainties in any engineering system study can be represented probabilistically or possibilistically. When sufficient historical data of the system variables is not available, a probability density function (PDF) might not be defined, while they must be represented in another... 

Increasing rate of demanding biodiesel as alternative energy resource, persuade researchers to investigate engine performance of biodiesel-fueled engines, which are highly influenced by ignition delay (ID) and combustion characteristics of such a fuel. This review article introduces a literature review on ignition delay (ID) and combustion characteristics of diesel engine fueled with biodiesel. Slightly difference between combustion characteristics of bio fueled engine and petroleum diesel one recognized as result of carried out investigations. Early start of combustion (SOC) and shorter ID of biodiesel comparing to diesel is reported by most of investigations. Lower compressibility, higher... 

Iran, as a developing country, will be confronted with a significant increase in electricity demand in future years. Being a petroleum producing country has resulted in extreme subsidies for energy production from fossilized resources such as oil and gas. This issue is one of the most important factors regarding underdevelopment of renewable energies in Iran. Expansive use of fossil resources in providing the necessary energy has resulted in Iran being among the 20 countries that have a share in the 75% spread of greenhouse gases. This issue has resulted in greater attention on behalf of the energy sectors policy makers regarding renewable energies, especially wind. Awareness regarding the... 

Proliferation of private distributed energy resources (DERs) necessitates devising effective energy management frameworks. This paper aims at establishing a decentralized model for the optimal dispatch of DERs in smart grids. The objective function is to minimize expected procurement cost of demand while profit of private DER owners is not sacrificed. Unit management modules (UMMs) embedded in private DERs and a central agent are autonomous agents of the model. The approach is iterative. In each iteration, the central agent announces to UMMs its procurement strategy, which contains purchased powers and their prices. Then, UMMs optimize and send back their output power and selling price... 

Proliferation of renewable energy resources in distribution networks has captured distribution companies' attention towards more active management tools. Thanks to the smart grid paradigm, hourly network reconfiguration, which is still among immature ideas, can bring the activeness required to handle fluctuating output of renewable resources. The aim of this study is to analyze the worthiness of the hourly reconfiguration in the presence of renewable energy resources. For doing so, a mathematical model is devised to minimize daily network losses via applying hourly reconfigurations. The model is a mixed integer second-order cone programming problem and is solved via MOSEK solver. The...