Sharif Digital Repository

Nowadays, due to the increasing importance and penetration of microgrids, solving the microgrid optimal sizing problem has become more important. The current utility grid and conventional energy sources are mainly ac, however, increasing rate of the replacement of the ac load with dc load lead to a more efficient dc system. So choosing the optimal type of microgrid as a way to increase efficiency of these systems would be a serious issue. This thesis establishes a planning model which finds the optimal size and type of a microgrid to minimize total cost. Total cost includes investment, operation and reliability cost of the microgrid. Sizes of DGs, converters and transformer linking the... 

As a matter of fact, power systems are always faced with a variety of uncertainties. These uncertainties change system parameters in an unwanted manner which may deteriorate the system security and reliability. For instance, a transmission line which is designed for a certain capacity may be suffered as a result of load increment and consequently may influence the normal operation of other network elements. In recent years, as a result of environmental considerations and especially after the oil shock at 1973 which caused the the energy prices to increase unprecedentedly, the human has taken more attention to renewable energies exploitation. Theses energies have a fluctuating nature and are... 

Smart grid brings miscellaneous concepts and advantages; increasing power quality, decreasing outages, motivating the consumers to participate in power system plans, and accommodating distributed generations (DG) are the most important purposes of smart grid implementation. Appearance of modern technologies makes operators devise better operation function. The effect of these technologies on the power system should be probed by sufficient criterions. In addition, preventing undesirable consequences of new technologies operation in the grid is the requirement of having smarter grid. In this thesis, based on the smart home concept two issues are discussed. In the first issue, a new algorithm... 

Toward the cost-effective solutions for the challenging features of maintenance in nowadays restructured power systems, reliability centered maintenance (RCM) has been introduced as the efficient key due to its streamlined performance. RCM, although has proven its noticeable merits in many industries, has not been yet furnished with efficient analytical methods in the power engineering context. In a power distribution system, vividly in a deregulated market and restructured environment, blind time based maintenance of all the distribution equipments is neither affordable nor economically justifiable. Moreover, an acceptable level of system reliability is an indispensable criterion for the... 

Power distribution systems have been traditionally operated as passive networks which consume electric power supplied by the transmission grid. Increasing utilization of wind energy in distribution systems, notably wind energy, is changing the way distribution sys-tems are operated. The distribution system operators (DSO) would operate the available wind power for reducing the power purchased from the wholesale market. However, high penetration of wind energy in distribution systems would require advanced operation mod-els and additional flexibility in system to offset the variability and uncertainty associated with wind energy. In addition, wind availability often does not positively... 

Implementation of telecommunication-based distribution automation is possible in both centralized and decentralized manners. Although centralized automation is more pervasive than decentralized automation, benefits of decentralized automation systems, like improving reliability and speeding up the fault management process, encourage distribution companies to implement these systems. However, high cost of decentralized automation can be a deterrent to most distribution companies. Therefore, economic planning and creating economic justifications for decentralized distribution automation are necessary for the development of these systems. In this dissertation, economic analysis and planning of... 

Considerable developments in demand-side real-time telemetry systems allow ISOs to use demand-side provided reserves in ancillary service markets. Presently, many ISOs designed programs to utilize the reserve provided by demand response resources in their market, and deploy them in emergency conditions. These programs are called ancillary service demand response (ASDR) programs. This thesis presents a stochastic programming model to schedule reserve provided by demand response resources in load buses of system. The demand-side reserve resources are modeled by demand response providers (DRP) which have the responsibility of aggregating and managing responses of customers. The reserve provided... 

In recent years, the pace of increment in electrical energy consumption is getting faster. Establishing new power-plants to keep a balance between generation and consumption not only has a high investment cost but also is a time consuming procedure. Thus, several studies have focused on the demand side management. Residential consumers possess remarkable portion of total electricity consumption. Accordingly, at first, the appropriate residential demand response program is selected based on presented experimental criteria. In the next step, since the network reliability is an important issue to the operators, the impact of implementation of the demand response program is studied on the... 

Nowadays, power systems are facing significant changes in traditional network operation and planning approaches with the introduction of distributed generation energy sources and increasing concerns about environmental issues. On the other hand, the Distribution Management System (DMS) in the current situation with low levels of observability and automation, controls and monitors the distribution network, which will not meet the challenges of the Active Distribution Network (ADN). For this purpose, in the first part of this dissertation, considering that the supply of network loads is important from the operator and distribution network management point of view and the voltage range and... 

The penetration of renewable energies in generation section of power systems caused many issues and challenges for planners, operators and decision makers. One significant challenge is the uncertainty and variability of this type of generation, which must be properly covered; otherwise it would lead to wide load and supply curtailments. In this regard, some system operators introduced a new product, named Flexible Ramping Product (FRP) to their markets. FRP is the ramp capability of market participants which is reserved to cover the uncertainty and variability of net load (load minus intermittent supply) at next market time-interval of real-time market. With this in mind, the energy storage... 

Singular differential equations have a wide range of applications. Hardy singularities, which are connected to inequalities of the same name and have various extensions, are the most well-known singularities. The application of Hardy inequalities in quantum physics and also in the linearization of reaction-diffusion equations in thermodynamics and combustion theory motivates researchers to examine them. Singularities on a domain's boundary are another well-known type of singularity. In the study of fluid mechanics and pseudoplastic flows, these singularities emerge.Differential equations with coefficients or functions that are simply functions belonging to $ L^1 $, or bounded Radon measures,... 

Application of special technologies is necessary for design and implementation of smart distribution systems. These technologies offer different facilities for users of distribution systems. One of the important goals of smart distribution systems is the improvement of reliability of local electricity services. This process requires information and data exchange between the smart devices and control center which applicable through communication infrastructure. If the communication infrastructure specified for automatic distribution faces to some problems, it is not possible to control the error because of absence of effective connection between the smart devices of network and control... 

The regulation is necessary for the electric distribution networks as a natural monopoly. Regulators have been applied the Performance Based Regulation (PBR) for the control of price. The common model of PBR is price cap. Price cap creates sufficient incentive for cost efficiency. However, it decreases the service quality in distribution systems. The aim of this thesis is to design a comprehensive model for improvement of service reliability in the presence of PBR. An incentive model is developed using reward-penalty theory and yardstick theory. Reward-penalty theory is a financial approach that rewards the utility with good reliability and penalizes the utility with poor reliability. The... 

Renewable energy resources, e.g. wind, solar and geothermal, experience rapid progresses in electric power industry all over the world. So, it becomes essential that these free-emission electrical energy resources be integrated in the existing generating capacity planning procedures. On the other hand, the uncertain and intermittent nature of these energies has led to some problems in their integration in power systems. The reserve requirement in a renewable-based power system is a main challenge, which has to be addressed properly. In this way, this research presents an analytical approach, based on the modified PJM method, to quantify the risk of renewable energies commitment during the... 

In recent years, because of power system restructuring and load growth, much of transmission lines are reaching to their maximum capacity. Therefore, it is so essential to upgrade existing transmission system. However, constructing new lines is a very expensive and time consuming method. Dynamic thermal rating of overhead line is an alternative solution for upgrading transmission system capacity. In this method, allowable current capability of line in the next duration is calculated according to the environmental conditions. A method should be developed to perfectly model these environmental changes. Fuzzy method is a powerful tool that models uncertainties and measurement errors in a simple... 

In most countries Frequency control services as one of the Ancillary services are presented in market scheme. Frequency control are used in different levels to balance generation and demand. Each reserve levels is implemented with specific characteristics and rules. Clearance of energy and one control reserve has some drawbacks so in this thesis we try to clear energy and different reserve levels simultaneously. Each reserve level is determined with special criteria. This criterion in primary reserve is frequency deviation restriction and unit commitment risk in territory reserve that is determined by system operator. In this thesis these two criteria are formulated in linear form and... 

World environmental concerns sharp increase in necessity of using energy in comparison with permanent progress in the field of renewal energy technologies causes modern forms of energy sources which can be used by public. This project studies the increasing influence of the wind power in power systems and also designing and exploiting techniques of local saving energy systems. For this purpose, models and possibilities in order to anticipate the operation of wind farm which is connected to grid by saving energy is described. In this project, the operation of compound system components which is totally a combination of three systems is being studied. The considered compound systems consist of... 

Direct/inverse scattering of high frequency SH-waves by a circular micro-/nano-fiberembedded in an infinite elastic isotropic medium is addressed in the framework of couple stresstheory with micro inertia. The inadequacy of classical theory of elasticity in the problems dealingwith propagation of high frequency waves as well as the problems concerning the elastic fields inthe vicinity of micro-/nano-size defects in which the wavelengths and the size of the defects arecomparable to intrinsic length of the material is well-known. These dilemmas can be remedied byemploying the more accurate higher order continuum theories. So, in the context of couple stresstheory with micro inertia, the... 

Promising advancement in smart technologies, in terms of information, control and communication infrastructures, along with utilization of demand response (DR) and distributed energy resources in system operation is transforming the legacy power systems to smart electricity grids. Smart grid operators would be able to utilize flexibility of loads and electricity energy storage (EES) systems for secure and economic operation of power systems.
The idea of DR and EES participation in wholesale energy markets is proposed in this thesis. A hierarchical framework for DR participation in day-ahead energy markets is developed in which DR aggregators aggregate small customers’ load reduction and... 

One of the important problems in fulfilling the consumers' power demand that has been especially intensified after restructuring is transmission line congestion. To solve this problem, either new transmission lines should be constructed or the existing transmission lines should be better utilized. Construction of new transmission lines is both expensive and time consuming. Therefore, it is usually better to enhance the utilization of the existing transmission assets. FACTS devices have been introduced over the past decades to enhance power systems operation. However, wide scale deployment of them has not occurred yet due to their high initial investment cost and some other problems. In order...