Sharif Digital Repository

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... 

In the view of the latest status and the potential of developing wind energy in South Africa, the present study aims to perform technical–economic–environmental analysis on a wind turbine system with HOMER software using the 20-years average data of the wind speed obtained from NASA's database, for providing the electricity to residential buildings. The results showed that the Port Elizabeth station, had the lowest levelized cost of electricity (LCOE) with the value of -0.363 $/kWh when using the EOLO wind turbine, and the Bloemfontein station had the highest LCOE with the value of 1.601 $/kWh when using the Turby wind turbine. The results from the step-wise assessment ratio analysis... 

Fast growth of wind power generation and its contribution in power systems dynamic performance has highlighted the importance of developing generic models for wind turbines. Following the former efforts, an enhanced version of standard generic wind turbine model is proposed in this article. The enhancements are aimed to make the model applicable for unbalanced Root Mean Square (RMS), short-Term frequency stability, and low-voltage ride-Through (LVRT) studies. Moreover, fidelity of the overall responses of the model is increased. To achieve these goals, five new blocks are designed and added to the base model and three existing blocks are modified. The new blocks are negative-sequence... 

Today, coordinated expansion planning is one of the key challenges for electricity systems including active distribution networks (ADNs) and transmission networks (TNs) hosting distributed renewable generation as well as large-scale wind energy generation. Accordingly, this study presents a decentralised hybrid robust and stochastic (HR&S) expansion planning optimisation method to determine a robust generation and transmission planning for a TN and stochastic expansion planning for ADNs. The proposed HR&S planning model is formulated with the objective of achieving an effective expansion of both TN&ADN while minimises the investment and operation costs of TN&ADN planning considering wind... 

This paper presents a new method for protecting the variable speed wind turbines in switching between different regions. With the objective of power maximization, the controller is applied in all regions. Since usually different methods and algorithms are used in different regions for controlling the wind turbines, smooth transition between these controllers is necessary for the safety and protection of turbine parts and structure. A two degree of freedom mechanical model is used and the simulations are performed and verified by FAST. The turbine is controlled by a rotor angular speed controller in the second region and an inverse dynamic pitch controller in the third region. The transient... 

Plasma actuator is a flow control device to improve the aerodynamic performance of wind turbine blades at low airspeeds. One of the most robust numerical models for simulation of plasma actuator interaction with the fluid flow is the electrostatic model. This model is improved recently and is extensively verified by the authors. Due to the high cost of performing experimental optimizations, the optimized geometrical dimensions and materials of a plasma actuator may be sought by this numerical model. The aim of the present study is the aerodynamic enhancement of a DU21 wind turbine blade airfoil in which the effect of geometric parameters and the dielectric material is examined separately.... 

This article addresses a centralized generation expansion planning problem, accounting for both long- and short-term uncertainties. The long-term uncertainty (demand growth) is modeled via a set of scenarios, while the short-term uncertainty (wind power generation) is described by a family of probability distributions with the same first- and second-order moments obtained from historical data. The resulting model is a distributionally robust chance-constrained optimization problem, which selects the conventional generating units to be built among predefined discrete options. This model includes a detailed representation of unit commitment constraints. To achieve computational tractability,... 

Safe pitch angle-based pole–zero–gain scheduling, and controller blending of H∞ controllers for a variable-speed variable-pitch wind turbine in the full load region are introduced in this paper. The design methodology ensures proper model reduction and modification, canonical controller realization, and cancellation of the hidden coupling terms that emerge from these scheduling procedures to maintain the stability of the closed–loop dynamics during wind turbine operation. In contrast to previous multi-model designs that either involve scheduling of complex transfer functions or depend on less-reliable wind speed estimations, in the presented framework only a portion of the controller is... 

This paper describes the design and implementation of a H∞-based robust controller for a commercial 2MW variable-speed variable-pitch wind turbine. The single controller is able to deliver specification performance for the entire full load region. Various aspects of modeling and design procedures including reduced order model validation, torsional mode damping of drivetrain and uncertainty estimation are explained in detail. To make the design more reliable and industrially attractive, simple routines for the derivation of required weighting functions are introduced. To investigate the benefits of the suggested design, its closed-loop performance is compared with the wind turbine's baseline... 

A robust multivariable strategy for pitch and torque control design of variable-speed variable-pitch wind turbines in the full load region is introduced in this paper. The pitch and torque control loops that share the tracking and active damping of drivetrain torsional mode objectives are designed simultaneously using a novel decomposition scheme. This permits the systematic design of robust multivariable controllers for wind turbines in a manner that facilitates industrial application. We achieve this by making the process of weighting function design fast, intuitive, and simple and by giving the designer a clear insight on the compromising aspects of the various control system objectives.... 

The objective of the present study is the development of an optimization model for identifying the best configuration of renewable-based integrated energy systems. The system includes a combination of renewable energy systems such as wind, solar, hydropower and hydrogen production, storage facilities and conventional fossil-fuel generators. The developed tool consists of various modules where water heating assumes the utilization of waste energy as an option. Furthermore, the application, which is demonstrated for a case study in Tehran, has been considered. The power exchange with the distribution network and injection of hydrogen produced from excess renewable sources into gas network are... 

Water shortage issues are growing through the globe at higher rate than population growth. On the bright side, various methods are devised to capture energy from renewable energy or waste heat from different sectors. Among all inspected approaches, waste heat capturing through cooling process of the wind turbines' generators for desalination at small scale is paid less attention. However, in large wind farms, the scale of this dissipated thermal heat becomes appreciable which can drive several desalination units. Due to the above-pointed facts, the waste heat of a wind turbine with nominal capacity of 7358 kW and height of 24 m for desalinating seawater is inspected here, using a... 

The Supply of sustainable freshwater has turned into a fundamental problem in numerous countries. The increment in population, the industrialization of the world, and variation in global warming temperatures lead to an increase in droughts, storms, and floods around the world. Therefore, the problems of water scarcity appear worldwide. Contrary to popular belief, the largest reserves of water are available in the air. Accordingly, several technologies have been developed for the production of drinking water from humid air in the research works. But, the critical problem is the high energy consumption in this equipment. Therefore, the issues of water-energy nexus are the particular subject in... 

The capacity factor is an important wind turbine parameter which is ratio of average output electrical power to rated electrical power of the wind turbine. Another main factor, the AEP, the annual energy production, can be determined using wind characteristics and wind turbine performance. Lower rated power may lead to higher capacity factor but will reduce the AEP. Therefore, it is important to consider simultaneously both the capacity factor and the AEP in design or selecting a wind turbine. In this work, a new semi-empirical secondary capacity factor is introduced for determining a rated wind speed at which yearly energy and hydrogen production obtain a maximum value. This capacity factor... 

Integrated transmission expansion planning (TEP) and generation expansion planning (GEP) with Wind Farms (WFs) is addressed in this paper. The optimal number of expanded lines, the optimal capacity of WFs installed capacity, and the optimal capacity of wind farms lines (WFLs) are determined through a new TEP optimization model. Furthermore, the optimum capacity additions including conventional generating units is obtained in the proposed model. The Benders decomposition approach is used for solving the optimization problem, including a master problem and two sub-problems with internal scenario analysis. In order to reduce the computational burden of the multi-year and multi-objective... 

This paper proposes an indirect load control demand response (DR) strategy for residential houses. A Stackelberg game theory is applied to account for the interaction between the aggregator in one side and the consumers on the other side. The aggregator, which owns a wind power plant, strives to maximize wind power utilization by consumers. Therefore, it motivates the consumers to adjust their load demand according to the forecasted wind power production by offering a bonus to them. On the other hand, consumers attempt to achieve the highest amount of reward by changing their load profile. It is assumed that each consumer has a critical load of which they have no control, and also a flexible... 

Load shedding (LS) is one of the most important protection schemes to prevent system blackout. In the case of largedisturbances, optimal LS in appropriate buses can effectively maintain the system stability. The higher complexity and lowerpredictability of modern power systems with high wind power penetration make it difficult to rely on conventional LS schemes,which shed a fixed, predetermined amount of load regardless of disturbance location. This study presents an intelligent LSscheme based on synchrophasor measurements that are adapted to both disturbance size and power system inertia. Theproposed scheme utilises improved power flow tracing method to determine the amount and location of... 

This article provides an agent-based model of a hypothetical standalone electricity network to identify how the feed-in tariffs and the installed capacity of wind power, calculated in percentage of total system demand, affect the electricity consumption from renewables. It includes the mechanism of electricity pricing on the Day Ahead Market (DAM) and the Imbalance Market (IM). The extra production volumes of Electricity from Renewable Energy Sources (RES-E) and the flexibility of electrical consumption of industries is provided as reserves on the IM. Five thousand simulations were run by using the agent-based model to gather data that were then fit in linear regression models. This helped... 

A novel fault ride-through strategy for wind turbines, based on permanent magnet synchronous generator, has been proposed. The proposed strategy analytically formulates the reference current signals, disregarding grid fault type and utilizes the whole system capacity to inject the reactive current required by grid codes and deliver maximum possible active power to support grid frequency and avoid generation loss. All this has been reached by taking the grid-side converter’s phase current limit into account. The strategy is compatible with different countries’ grid codes and prevents pulsating active power injection, in an unbalanced grid condition. Model predictive current controller is... 

The fast growth of technologies most of which depend on natural sources of energy has resulted in a huge consumption of fossil fuels. In this regard, many solutions have been suggested to alleviate the side effects such as air pollution and global warming. Among these solutions, mobile storages like electric vehicles (EVs) and renewable generations, have grown significantly due to being more applicable. But uncoordinated operation and uncertain nature of these distributed energy resources (DERs) can bring forward new challenges and issues to the operators of power system. Thus, in many cases it is more efficient to co-operate them in a hybrid system. In this study, we address a virtual power...