A joint model of destination and mode choice for urban trips: A disaggregate approach

, Article Transportation Planning and Technology ; Volume 36, Issue 8 , Jul , 2013 , Pages 703-721 ; 03081060 (ISSN) Seyedabrishami, S ; Shafahi, Y ; Sharif University of Technology

2013

Abstract

Trip destination and mode choice are highly influenced by travelers' perceptions and behaviors; selecting a destination and a vehicle for a trip are two interdependent problems. This paper presents and applies a disaggregate joint model for traveler destination and mode choice. The choice model uses fuzzy set and probability theory to deal with the uncertainty embedded in travelers' perceptions and behaviors. The model is structured as a decision tree in which the fuzzy and non-fuzzy classification of influential variables regarding destination selection and mode choice expand the tree. The most influential explanatory variables among all the variables categorized for travelers' household,...

Uncertainty Analysis in Urban Travel Demand Estimation Using Fuzzy Theory

, Ph.D. Dissertation Sharif University of Technology Seyedabrishami, Ehsan (Author) ; Shafahi, Yousef (Supervisor)

Abstract

Travel demand estimation is a complicated process as travel demand is highly influenced by uncertainties. These uncertainties can be analyzed in two levels: aggregate and disaggregate. Models in aggregate level are usually influenced by uncertainties in data insufficiency in some regions of data space because of non uniform distribution of input data. Uncertainties embedded in travelers’ perceptions of some influential variables on demand estimation (such as travel time) moreover affect these models. An expert-guided algorithm to incorporate expert knowledge into adaptive network-based fuzzy inference system for compensating data insufficiency and considering uncertainties inherent in...

Estimating time-dependent origin-destination demand from traffic counts: Extended gradient method

, Article Transportation Letters ; Volume 7, Issue 4 , 2015 , Pages 210-218 ; 19427867 (ISSN) Shafiei, M ; Nazemi, M ; Seyedabrishami, S ; Sharif University of Technology

Maney Publishing 2015

Abstract

Time-dependent origin-destination (TDOD) demand is a key input of dynamic traffic assignment (DTA) in advanced traffic management systems. Model reliability is highly dependent on the accuracy of this information. One method to achieve TDOD demand matrices is to use a primary demand matrix and traffic volume counts in some links of a network. This paper proposes a bi-level model to correct the TDOD demand matrix. The extended gradient method (EGM) - an iterative method that minimizes the discrepancy between the counted and estimated traffic volumes - is a suggested means to solve this problem. The methodology is first tested on a small synthetic network to verify its performance. Then, it is...

A fuzzy traffic assignment algorithm based on driver perceived travel time of network links

, Article Scientia Iranica ; Volume 18, Issue 2 A , 2011 , Pages 190-197 ; 10263098 (ISSN) Ramazani, H ; Shafahi, Y ; Seyedabrishami, S. E ; Sharif University of Technology

2011

Abstract

Traffic assignment is a step of travel demand estimation. Given a trip origin-destination demand matrix, this step determines traffic flow in each link, according to assumptions based on the behavior of drivers. Conventional assignment algorithms, which are mostly based on the Wardrop first principle of user equilibrium, assume that all drivers choose the shortest path to the destination, based on the same travel time computed by travel time functions. However, in reality, driver perception of travel time varies for a specific route. This paper presents a traffic assignment algorithm which assumes that driver perception of travel time affects route choices. Fuzzy set theory is used to define...

A shortest path problem in an urban transportation network based on driver perceived travel time

, Article Scientia Iranica ; Volume 17, Issue 4 A , August , 2010 , Pages 285-296 ; 10263098 (ISSN) Ramazani, H ; Shafahi, Y ; Seyedabrishami, S. E ; Sharif University of Technology

2010

Abstract

This paper proposes a method to solve shortest path problems in route choice processes when each link's travel time is a fuzzy number, called the Perceived Travel Time (PTT). The PTT is a subjective travel time perceived by a driver. The algorithm solves the fuzzy shortest path problem (FSPA) for drivers in the presence of uncertainty regarding route travel time. For congested networks, the method is able to find the shortest path in terms of perceived travel time and degree of saturation (congestion) along routes at the same time. The FSPA can be used to support the fuzzification of traffic assignment algorithms. The applicability of the resulting FSPA for the traffic assignment was tested...

Fuzzy trip distribution models for discretionary trips

, Article 11th International IEEE Conference on Intelligent Transportation Systems, ITSC 2008, Beijing, 10 December 2008 through 12 December 2008 ; December , 2008 , Pages 557-562 Shafahi, Y ; Nourbakhsh, S. M ; Seyedabrishami, S ; Sharif University of Technology

2008

Abstract

Trip distribution is considered as the second step in urban transportation planning. The important factors which affect trip distribution are the characteristics of origins and destinations and travel impedance between O/D. Trip distribution traditionally models with the deterministic variables although it seems affective variables in trip distribution molding are based on human perceptions. Since perceptions of people vary from one person to another, thus variables are imprecise and vague. Fuzzy approaches are proper tools of modeling non-deterministic variables. In this paper we present fuzzy estimation models of trip distribution for discretionary trip purposes including: shopping,...

Genco's Bidding Strategy in Day-Ahead Energy Market Considering Demand Response

, M.Sc. Thesis Sharif University of Technology Kazemi, Mostafa (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

Since 1980s the electricity market has been gradually evolving from a monopoly market into a liberalized one for encouraging competition and improving efficiency. This brings the opportunity for generation companies (Gencos) to make more proﬁts while embracing more risks of not being dispatched. Therefore, it has become a core interest for the Gencos to develop optimal bidding strategies to maximize the proﬁts and minimize the risks while participating in such a competitive market. Error of determining day-ahead electricity price is one of the sources of the risk. Energy price has a high impact on bidding strategy optimization process. So it should be determined with low error which is not...

Multi Objective Distributed Generation Planning in a Flexible Environment

, Ph.D. Dissertation Sharif University of Technology Soroudi, Alireza (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

The process of deregulation that has involved electricity many markets has introduced several new interesting research topics in power system area. This thesis addresses one of the most fascinating issues among them: the study of distributed generation both renewable and conventional integration in distribution networks. From the distribution network operator (DNO)'s point of view, it is of interest to develop a comprehensive methodology which considers various distributed generation technologies as an option for supplying the demand in distribution networks. In this thesis, the planning problem has been multi-objectively modeled. This will help the planner in decision making while knowing...

, M.Sc. Thesis Sharif University of Technology Mahmoodzadeh, Zahra (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

Losses are unavoidable in any parts of power systems, from generation to receiving nodes and occur in transmission and distribution networks. However, the main loss component is produced in distribution networks. Energy losses in distribution networks are about 70% of technological transport energy losses.
Energy losses in distribution networks are an important indicator for the planning and operation of the system. A fast, reliable and accurate energy loss calculation method is required for optimal operation of the distribution networks.
Energy loss depends on network's operating conditions. Loads values and loads factors are time variables; therefore, methods based on probability...

Methods of Clearing Reactive Power Market and Cost Allocation in Pool Structure

, M.Sc. Thesis Sharif University of Technology Kharraty, Saeed (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

Restructuring and privatization in power system such as any industry leads to better market operation and more social welfare. Since two decade the power system in many countries have changed from monopoly to free market. In a restructured network the technical and economical aspects should be considered together. Ancillary services are needed for any power system to be operated in an optimal and secure manner. Reactive power and voltage regulation is one of the most important ancillary services in the network. this service should be supplied by its providers through a competitive market and system operator determines the optimal dispatch among different bids. The cost of purchasing reactive...

Dynamic Security Assessment in Restructured Power Systems

, Ph.D. Dissertation Sharif University of Technology Kheradmandi, Morteza (Author) ; Ehsan, Mahdi (Supervisor)

Abstract

This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems and issues arising in its applications. The new electric utility environment has an immedi-ate consequence of emphasis on reliability and secure operation of power systems. This requires faster and more precise methods to assess the dynamic aspect of se-curity. On the other hand, this issue is becoming challenging when the determined dispatch might not be accommodated due to violation of the limits.This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems...

Optimal Sizing and Operation of CHP Based on Stochastic Programming

, M.Sc. Thesis Sharif University of Technology Bozorg, Mokhtar (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

CHP (Combined Heat and Power) generates electricity and thermal energy simultaneously from input fuel. Since it has high energy efficiency and low installation time, it is an appropriate approach in energy management of residential complexes. In this project, stochastic programming based on Monte Carlo approach is used to handle uncertainties in the optimal sizing of CHP for residential complexes. Availability of CHP, boiler and AC bus as well as the electrical and thermal load forecast errors are considered as stochastic variables. Minimizing system total cost considering the probability of each scenario obtained from the scenario reduction algorithm is the objective function. The system...

Planning of Energy Storage Systems with the Main Goal of Managing the Output Power of Wind Farms

, M.Sc. Thesis Sharif University of Technology Saber, Hossein (Author) ; Ehsan , Mehdi (Supervisor)

Abstract

Uncertain fuel prices and also global climate changes are accompanied by some state initiatives such as renewable portfolio standards (RPS). This has caused a fast growth in the amount of renewable energy installed worldwide especially wind energy over last decades. However, the intrinsic characteristics of wind farms output power, i.e. intermittency and volatility of wind speed along with being non-dispatchable in output generation of wind turbine raises many new technical and financial challenges for power system operators and planners. Up to these issues, large level of wind power penetration causes a growing concern in wind energy curtailment issue which the wind farm’s operator may be...

Retailer’s Medium-term Planning in Distribution Network Considering Uncertainty and Competitive Enviroment

, Ph.D. Dissertation Sharif University of Technology Kharrati, Saeed (Author) ; Ehsan , Mehdi (Supervisor)

Abstract

Electricity retailers are one of the power market entities which act as an intermediary between the producers in the wholesale market and the consumers in the retail side. The main task of a retailer in the power market is to set contract with the consumers to supply their electricity during a pre-specified time period and to participate in the wholesale market to supply the electricity needed by its costomers. Retailer’s contract with its customers may be a simple contract with a fixed pre-determined energy price or include some more complicated feathures such as involvement of a percent of green energy or variable price and demand response contracts. Moreover, retailer can supply its...

Scheduling of Retailers Performance in Electrical Energy Markets with Energy Production;Sell in Pool Market; and Demand Response Policies

, M.Sc. Thesis Sharif University of Technology Gilasi, Yasin (Author) ; Ehsan, Mehdy (Supervisor)

Abstract

Recent years of capitalism bold role and the competitive environment of variant fields of our life, sparking the idea which considers the electricity (one of the most crucial human requirement) as a commodity of a competitive market to be traded between confident subscribers by easy access. Therefore, by converting the exclusive structure of electricity supply system to a competitive one, some new roles are created to fulfill the electricity generation, transmission and distribution processes. Retail is one of the new roles, defined as a power system restructuring development helper by support of electricity trading, which can be involved in different transactions according to the market...

Linked Planning of Power Grids and Subsidy Policies on Using Photovoltaic Cells for Residential Electricity Supply

, M.Sc. Thesis Sharif University of Technology Balmaki, Saeed (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

In recent years, due to restructuring in the electric power industry, distributed generation has become one of the most important subjects and DGs and renewable energy sources have been increasingly expected as a supplement and an alternative to a conventional large scale central power system. their success depends not only on the distribution of the available renewable energy sources in a region but also on the power grids connectable capacity in the area. Photovoltaic system is one of the best RESs for residential electricity supply because it is noiseless and solar power is widely available and households can use it via photovoltaic cells in their homes. There are two major problems...

Bidding and Offering Strategy of Hybrid Electric Companies in Day-ahead Energy Market

, Ph.D. Dissertation Sharif University of Technology Kazemi, Mostafa (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

This Thesis presents a new approach for determining the day-ahead bidding strategies of a hybrid electric energy company. The company has both energy generation and energy retailing businesses in a competitive electricity market. Demand response programs are also considered in the retail side of the company in order to hedge the risk of participation in wholesale market. Price-taker and price maker companies are considered in this thesis separateky.For the price-taker hybrid structure, the predivtion of day-ahead prices are used to evaluate the optimum bidding and offering strategies. Also, day-ahead market price uncertainty is modeled, using non-probabilistic Information Gap Decision Theory...

Security Constrained Unit Commitment With Natural Gas Transmission Delivery Constraints

, M.Sc. Thesis Sharif University of Technology Badakhshan, Sobhan (Author) ; Ehsan, Mahdi (Supervisor)

Abstract

Natural gas power plant installed in power system as rapid start unit. In the recent decades, with increasing in the number of gas generating units in the world, consideration of natural gas transmission network in optimal solution of security-constrained unit commitment (SCUC) become a non-negligible problem. The gas transmission grid constraints integrated into the scheduling of thermal units in the proposed model for minimizes power system operating cost. In a power plant transmission of natural gas to power plant is very important because congestion in natural gas pipeline increases. This model could consider natural gas storage tank in gas transmission network as decision variable....

Distributed Generation Planning in Deregulated Electric Industry Using Multi-objective Optimization

, M.Sc. Thesis Sharif University of Technology Ahmadi, Mohammad (Author) ; Ehsan, Mehdi (Supervisor)

Expansion Planning of Active Distribution Networks in the Gradual PV
Increase

, M.Sc. Thesis Sharif University of Technology Khorshidi, Saman (Author) ; Ehsan, Mehdi (Supervisor)

Abstract

Due to the increasing influence of distribution generation , their effect in planning can't be ignord , especially solar panels ,which are incresing rapidly. The main purpose of this thesis is to an active distribution network that annually load bus and the amount of photovoltaic production in it increases and plan dynamically. In the planning that is done , uncertanty in the amount comsumption load and uncertanty in the pattern of sunlight and also annual innterest rates in the classical system we have planned by optimizing the network expansion costs , in addition to supplying the load bus, we can keep the voltage drop bus and line filling within the allowable . To do this , we considered...