Sharif Digital Repository

Secure and reliable operation is one of the main challenges in restructured power systems. Wind energy has been gaining increasing global attention as a clean and economic energy source, despite the operational challenges its intermittency brings. In this study, we present a formulation for electricity and reserve market clearance in the presence of wind farms. Uncertainties associated with generation and line outages are modeled as different system scenarios. The formulation incorporates the cost of different scenarios in a two-stage short-term (24-hours) clearing process, also considering different types of reserve. The model is then linearized in order to be compatible with standard... 

In this letter, an incentive compatible contract is designed for purchasing energy and ancillary service (AS) simultaneously from strategic frequency regulation service providers (FRSPs) by considering information asymmetries between independent system operator and FRSPs. Here, AS is confined to frequency reserve (FR) for arresting nadir frequency following possible contingencies of the electrical grid. An FRSP has a multi-dimensional private information vector, which determines its operational cost and limitations. Moreover, there is a gaming opportunity for an FRSP that is arisen between energy and AS payments manifesting by manipulation of its bids. Thus, in this letter, a multi-object... 

Demand response (DR) is known as a key solution in modern power systems and electricity markets for mitigating wind power uncertainties. However, effective incorporation of DR into power system operation scheduling needs knowledge of the price–elastic demand curve that relies on several factors such as estimation of a customer’s elasticity as well as their participation level in DR programs. To overcome this challenge, this paper proposes a novel autonomous DR scheme without prediction of the price–elastic demand curve so that the DR providers apply their selected load profiles ranked in the high priority to the independent system operator (ISO). The energy and reserve markets clearing... 

Optimization of wind farm (WF) layout has been studied in the literature with the objective of maximizing the wind energy capture. Based on the power spectrum density theorem, this paper shows that the WF layout affects not only the total harvested energy but also the level of power fluctuation, which, in turn, influences required capacity of battery energy storage system (BESS) needed to mitigate the inherent power fluctuation of the WFs. Since, both harvested energy level and BESS capacity directly influence the profit of WF owner, the effect of WF layout on these quantities is taken into account simultaneously, and WF layout optimization problem is redefined. Genetic algorithm is then... 

Purpose: Microgrids are inclined to use renewable energy resources within the availability limits. In conventional studies, energy interchange among microgrids was not considered because of one-directional power flows. Hence, this paper aims to study the optimal day-ahead energy scheduling of a centralized networked multi-carrier microgrid (NMCMG). The energy scheduling faces new challenges by inclusion of responsive loads, integration of renewable sources (wind and solar) and interaction of multi-carrier microgrids (MCMGs). Design/methodology/approach: The optimization model is formulated as a mixed integer nonlinear programing and is solved using GAMS software. Numerical simulations are... 

Multicarrier energy systems have provided the opportunity for users who are experiencing only must-run loads to participate in demand response programs by using self-generation units. In this paper, a bilevel game between so-called energy retailers and consumers with firm loads (as subsystems) is formulated in a multicarrier energy system. In the first level of this game, energy retailers offer selling prices for different energy carriers to maximize their profit. Consequently, consumers react to the offered prices by managing their purchasing power from the retail market to minimize their energy bill in the second level. The proposed approach leads to a mixed integer nonlinear programming... 

Electrification involves many activities that have detrimental impacts on environment. Over the last few years, many studies have been conducted to understand, estimate and mitigate the carbon footprint of electricity distribution but other environmental aspects of electrification remain almost neglected. In recent years, electricity distribution companies have adopted many waste management techniques to reduce the amount of waste generated in their key processes. However, the causes of waste and the necessary corrective actions to alleviate the waste generation in electricity distribution have not been studies in an integrated framework. In current study, which was conducted to fill this... 

Electricity demand forecasting has been a real challenge for power system scheduling in different levels of energy sectors. Various computational intelligence techniques and methodologies have been employed in the electricity market for short-term load forecasting, although scant evidence is available about the feasibility of these methods considering the type of data and other potential factors. This work introduces several scientific, technical rationales behind short-term load forecasting methodologies based on works of previous researchers in the energy field. Fundamental benefits and drawbacks of these methods are discussed to represent the efficiency of each approach in various... 

Stand-alone hybrid power systems are an alternative to main electricity grids, where the grid extension is costly or the trifling local consumption would not justify its expansion. However, lack of consistency and uniformity in renewable energy sources, and the restrictions of energy storage systems make system sizing a challenging task. Optimum size of a stand-alone system depends on several factors including energy demand function. In this paper, different types of demand functions are addressed for optimising a solar-hydrogen supply system. Different parameters are defined to investigate the impact of household population on the power generation cost, and also to determine the optimum... 

This paper focuses on expansion co-planning studies of natural gas and electricity distribution systems. The aim is to develop a mixed-integer linear programming (MILP) model for such problems to guarantee the finite convergence to optimality. To this end, at first the interconnection of electricity and natural gas networks at demand nodes is modelled by the concept of energy hub (EH). Then, mathematical model of expansion studies associated with the natural gas, electricity and EHs are extracted. The optimization models of these three expansion studies incorporate investment and operation costs. Based on these separate planning problems, which are all in the form of mixed-integer nonlinear... 

Demand-side management (DSM) and the integration of the energy hub concept as a main part of future energy networks play an essential role in the process of improving the efficiency and reliability of the power grids. In this paper, we consider a smart multi-carrier energy system in which users are equipped with energy storage and conversion devices (i.e., an energy hub). Users intend to reduce their energy payment by shifting energy consumption to off-peak hours and switching between different energy carriers. This system enables both users with shiftable loads and must-run loads to be active in a DSM program. We apply game theory to formulate the energy consumption and conversion for a... 

This paper focuses on expansion co-planning studies of natural gas and electricity distribution systems. The aim is to develop a mixed-integer linear programming (MILP) model for such problems to guarantee the finite convergence to optimality. To this end, at first the interconnection of electricity and natural gas networks at demand nodes is modelled by the concept of energy hub (EH). Then, mathematical model of expansion studies associated with the natural gas, electricity and EHs are extracted. The optimization models of these three expansion studies incorporate investment and operation costs. Based on these separate planning problems, which are all in the form of mixed-integer nonlinear... 

Demand-side management (DSM) and the integration of the energy hub concept as a main part of future energy networks play an essential role in the process of improving the efficiency and reliability of the power grids. In this paper, we consider a smart multi-carrier energy system in which users are equipped with energy storage and conversion devices (i.e., an energy hub). Users intend to reduce their energy payment by shifting energy consumption to off-peak hours and switching between different energy carriers. This system enables both users with shiftable loads and must-run loads to be active in a DSM program. We apply game theory to formulate the energy consumption and conversion for a... 

Stand-alone hybrid power systems are an alternative to main electricity grids, where the grid extension is costly or the trifling local consumption would not justify its expansion. However, lack of consistency and uniformity in renewable energy sources, and the restrictions of energy storage systems make system sizing a challenging task. Optimum size of a stand-alone system depends on several factors including energy demand function. In this paper, different types of demand functions are addressed for optimising a solar-hydrogen supply system. Different parameters are defined to investigate the impact of household population on the power generation cost, and also to determine the optimum... 

A better performance and consequently the widespread use of polymeric insulators in different parts of the power grid can increase their role in the grid reliability. The accumulation of contamination and housing-erosion are the two most effective factors in undermining the performance of this type of insulators. Therefore, electric utilities need to identify contaminated insulators for washing and cracks in polymeric housing to replace them with healthy specimens. This paper discusses the impact of contamination layer and housing-erosion of polymeric insulators on the partial discharges (PD) at the insulator surface, through RF-PRPD (phase resolved partial discharge) patterns. The existence... 

We study the application of cooperative control and game theoretic approaches to wind farm optimization. The conventional (greedy) wind farm control strategy seeks to individually maximize each turbine power. However, this strategy does not maximize the overall power production of wind farms due to the aerodynamic interactions (wake effect) between the turbines. We formulate the wind farm power optimization problem as an identical interest game which can also be used to solve other cooperative control problems. Two model-free learning algorithms are developed to obtain the optimal axial induction factors of the turbines and maximize power production. The algorithms are simulated for a... 

The combination of concentrating photovoltaic (CPV) and organic Rankine cycle (ORC) systems not only leads to a reduction of photovoltaic (PV) operating temperature, but also leads to an additional electric power production. Increase in the temperature of the PV decreases its operating efficiency, while increases the ORC efficiency. Therefore, there is an optimum temperature in which the total electricity produced by the combined system will be maximum. In this study, a modified CPV/ORC system is simulated and the optimum operating temperature of the PV panel is determined for different PV efficiencies. The most striking result is that increase in the PV nominal efficiency will result in the... 

The appealing advantages of high-temperature superconducting (HTS) power transformers over conventional ones have attracted transformer manufacturing companies, power companies, research institutes, and universities worldwide to conduct research and development in this field. Unfortunately, HTS transformers are more vulnerable to mechanical stresses than conventional transformers. The results of the interaction between current carrying windings and leakage magnetic fluxes are the electromagnetic forces, which act on transformer windings. Under short circuit events, these forces are remarkable, and, therefore, catastrophic failure of transformer may arise. Flux-diverter applications have been... 

Due to the devastating ecological effects and constrained reserves of fossil fuels, renewable energies are now globally accepted as viable alternative sources of energy. Among renewable energy sources, wind energy has become globally popular, primarily because wind farms can be rapidly built and easily maintained at a relatively low cost. Wind-powered hydrogen production is an effective solution for storing the excess energy output of wind farms. The hydrogen produced in this way can be used not only in fuel cells but also in cooling, oil, gas, and petrochemical fields. As a country devastated by war and instability, Afghanistan has major energy generation challenges and a substantially... 

This article presents a mixed-integer linear stochastic model for the optimal expansion planning of electricity distribution networks and distributed generation (DG) units. In the proposed framework, autonomous DG units are aggregated and modeled using the well-known energy hub concept. In this model, the uncertainties of heat and electricity demand as well as renewable generation are represented using various scenarios. Although this is a standard technique to capture the uncertainties, it drastically increases the dimensions of this optimization problem and makes it practically intractable. In order to address this issue, a novel iterative method is developed in this article to enhance the...