Sharif Digital Repository

Doubly fed induction generators (DFIGs) are widely used in wind power systems; hence their reliability model is an important consideration for production assessment and economic analysis of wind energy conversion systems. However, to date mutual influences of reliability analysis, production estimations and economic assessments of wind farms have not been fully investigated. This study proposes a reliability model for DFIG wind turbines considering their subcomponent failure rates and downtimes. The proposed production estimation algorithm leads to an economic assessment for wind farms. A comprehensive spare parts management procedure is then presented in the study. As a case study,... 

In this work, the wind farm layout optimization problem is dealt with using a new approach. The aim of wind farm layout optimization is to maximize the output power of a wind farm considering the wake losses. Layout optimization minimizes the wake losses regarding the location of the turbines. Three different wind scenarios with different wind direction angles, wind direction blowing probabilities, and Weibull distribution parameters are assumed. Since, the problem is nonlinear and constrained, imperialist competitive algorithm is used as a modern and powerful algorithm for continuous optimization problems. The optimization outcomes indicate that imperialist competitive algorithm yields... 

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... 

Smartening of contemporaneous power delivery systems in conjunction with increased penetration of vehicle to grid (V2G) technology, changes the way market participants play their role in the market operation to maximize their profit. In V2G technology, plug-in electric vehicles (PEV) have bidirectional power flows i.e. they can either inject power to the grid or draw power from it. In recent years, the V2G technology has found a world wild attention due to its important advantages such as the peak load reduction and providing system reserve, to name a few. The unit commitment (UC) is a power system operation problem which is used to find the optimal operation schedule of generation units.... 

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... 

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... 

In this article, a high-accuracy hybrid approach for short-term wind power forecasting is proposed using historical data of wind farm and Numerical Weather Prediction (NWP) data. The power forecasting is carried out in three stages: wind direction forecasting, wind speed forecasting, and wind power forecasting. In all three phases, the same hybrid method is used, and the only difference is in the input data set. The main steps of the proposed method are constituted of outlier detection, decomposition of time series using wavelet transform, effective feature selection and prediction of each time series decomposed using Multilayer Perceptron (MLP) neural network. The combination of automatic... 

Distribution automation (DA) application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. As a result, various automation schemes have been developed and introduced in different countries and by different venders. The impacts of implementing a specific automation scheme on reliability indices of a given distribution system can be different from other available automation schemes. For this reason, when comparing the available automation schemes with each other or with the other reliability improvement measures, it is necessary to perform a course of reliability... 

This paper aims to quantitatively evaluate and compare the reliability impact of employing an automatic loop restoration scheme in a typical distribution system, with and without pulse closing technology. Sustained interruptions, momentary interruptions and voltage sags are the three major attributes of the service reliability that are taken into account in the reliability case studies  

Distribution automation (DA) application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. As a result, various automation schemes have been developed and introduced in different countries and by different venders. The impacts of implementing a specific automation scheme on reliability indices of a given distribution system can be different from other available automation schemes. For this reason, when comparing the available automation schemes with each other or with the other reliability improvement measures, it is necessary to perform a course of reliability... 

Distribution automation application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. For this purpose, various automation schemes have been developed and introduced in different countries and by different venders. However, the challenge for electric utilities, especially in today's competitive electricity market, is to identify and evaluate potential reliability reinforcement schemes. Accordingly, appropriate schemes must be determined and prioritized for implementation. In this context, reliability cost/worth assessment plays an important role. A comprehensive... 

Implementation of Distribution Automation (DA) in electric power distribution systems can result in customer satisfaction with improved reliability, consistent quality and high-tech services. Loop Restoration Strategy (LRS) is a special DA method in the feeder level which is used by electric utilities to improve distribution system reliability. The effects of the implemented LRS on the reliability indices of a given distribution system mainly depend on its Automatic Control System (ACS). Selecting the type of ACS of LRS by electric utilities relies on the level of improvement required at load points and system oriented reliability indices. A step by step evaluation procedure is proposed in... 

The present study presents a new risk-constrained bidding strategy formulation of large electric utilities in, presence of demand response programs. The considered electric utility consists of generation facilities, along with a retailer part, which is responsible for supplying associated demands. The total profit of utility comes from participating in day-ahead energy markets and selling energy to corresponding consumers via retailer part. Different uncertainties, such as market price, affect the profit of the utility. Therefore, here, attempts are made to make use of Information Gap Decision Theory (IGDT) to obtain a robust scheduling method against the unfavorable deviations of the market... 

This paper presented a combined scheduling and bidding algorithm for constructing the bidding curve of an electric utility that participated in the day-ahead energy markets. Day-ahead market price uncertainty was modeled using non-probabilistic information gap decision theory (IGDT). The considered utility consisted of generation units and a retailer part; the retailer part of the utility and its demand response program (DRP) could affect the utility's profit, which should be considered in the bidding strategy problem. The bidding strategy algorithm proposed in this paper dispatched units by optimizing the demand response programs of the retailer part. In addition, non-decreasing bidding... 

Deployment of battery energy storage system (BESS) is a viable option to alleviate the inherent power fluctuation of wind farms. In this paper, a novel model predictive control (MPC) scheme is presented in order to control the BESS dispatch in an integrated wind farm. The constraints of BESS are formulated and are taken into account in optimization problem. The predictive control is based on receding horizon which shows robustness and improved performance compared to the conventional BESS control strategies. The objective function is defined in order to minimize the deviation of wind power production relative to the scheduled production. The results showed the effectiveness of the proposed... 

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 (PSD) 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 wind farms. Since both harvested energy level and BESS capacity directly influence the profit of WF owner, the effect of WF layout on these quantities are taken into account simultaneously and WF layout optimization problem is redefined. Genetic algorithm... 

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... 

Recently, many investigations have been studied on the effects of the uncommon extreme events like hurricanes in electrical distribution grids. These events leads to damage to distribution grid equipments, and they are cause widespread blackouts. This paper presents short-term resilience enhancement of the residential sections against hurricane at day-ahead. The lines outage in the electrical distribution grid is implemented as stochastic modeling by hurricane. The resilience enhancement is done in the multiple energy systems such as integrated gas, heat and electrical. The three-stage multi-objective functions optimization is proposed for resilience-oriented enhancement. The proposed... 

The best energy transfer scenario (BETS) is a situation under which the optimum transfer of power (or energy) from the electric utility to an electric power consumer is achieved. Such a scenario is important because it is used as a reference point to evaluate how efficient the load operates. The index of power factor (PF) is used to quantify such an efficiency. The closer the PF to unity corresponds to more efficient performance of the load. This paper is to show that the conventional definition of the BETS is inadequate and results in an unfair value for the PF unless the transmission line is perfect and lossless (which is an unrealistic condition). The paper also investigates an... 

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...