Sharif Digital Repository

As the electricity market undergoes continuous evolutions, along with the outdated nature of the grid, system operators would have to be able to more effectively manage the operation costs since waves of maintenance costs and equipment investments would be anticipated in the years to come. Strategic implementation of cost-effective reliability centered maintenance (RCM) approaches seems to be a key solution. This paper proposes an efficient method to assess the component criticality for the system overall reliability and further maintenance focuses. A solution concept of game theory, called Shapely Value, that is able to fairly identify the contribution of each single equipment to the system... 

With the rapid evolution of electricity markets and the need for higher economic efficiency of power industry, attempts for lowering down the maintenance costs as a large portion of system operation expenses seem imperative. Recognised as a crucial step in practical implementation of modern maintenance paradigms, e.g. reliability-centred maintenance, this study proposes an efficient method to quantify the generating units' criticality on the bulk power system reliability performance. The proposed approach utilises a solution concept of game theory and evaluates the contribution of each generating unit on the overall system reliability when a higher-order contingency occurs. The suggested... 

Increasing redundant paths in transmission grids has always been thought to be a tool to enhance service reliability. However, network equations by intertwining power flows through redundant paths impose more limits on systems with more redundancy. Accordingly, autonomous removing of a few lines may relief capacity limit violations in some contingency events thereby enhancing service reliability. This paper aims to study impacts of manual removing of transmission lines on composite system reliability. For doing so, the existing model is extended to consider optimal transmission switching (OTS) as a remedial action. The model minimizes total damage cost imposed by load curtailments. The... 

As the electricity market undergoes continuous evolutions, along with the widely-recognized outdated nature of the grid, system operators would have to be able to more effectively manage the system operation expenses since waves of maintenance costs and equipment investments would be anticipated in a few years to come. Strategic implementation of cost-effective reliability-centered maintenance (RCM) approaches seems to be a key solution. This paper proposes an efficient method to assess the component criticality for system overall reliability and further maintenance focuses. A solution concept of game theory, called shapely value, is proposed that is able to fairly identify the contribution... 

Increasing redundant paths in transmission grids has always been thought to be a tool to enhance service reliability. However, network equations by intertwining power flows through redundant paths impose more limits on systems with more redundancy. Accordingly, autonomous removing of a few lines may relief capacity limit violations in some contingency events thereby enhancing service reliability. This paper aims to study impacts of manual removing of transmission lines on composite system reliability. For doing so, the existing model is extended to consider optimal transmission switching (OTS) as a remedial action. The model minimizes total damage cost imposed by load curtailments. The... 

Optimal transmission switching (OTS) along with optimal bus-bar switching, also known as network topology optimization (NTO), has been previously proposed and utilized as a powerful tool to reduce operational costs. However, operational constraints and reliability considerations of NTO problem have not been addressed properly. In this paper, operational constraints are integrated in NTO problem and the effect of transmission network switching on expected interruption cost (EIC) is investigated. Moreover, a novel approach based on pool of solutions approach is presented, which can generate various switching scenarios. In doing so, the decision maker would be able to analyze and choose the... 

The main focus of this paper is to find an upgrade plan for a microgrid. This plan includes system lines' upgrades, the place, and size of the new capacitors and DERs. As usual, the planning process is begun with the load forecasting. The main objectives include minimization of system upgrade cost, loss cost, loss cost in peak load, and finally demand cost. The last objective is realized here using the tap changer of the main station transformer and reactive power support of the sources available or planned for the future of the grid. This is always referred to as the conservation of voltage reduction. In order to consider the effects of bus voltages on the system demand, the ZIP model for... 

Nowadays, communication protocols are used in safety-critical automotive applications. In these applications, fault tolerance is a main requirement and the existence of single points of failure is a serious threat to system failures. Among the communication protocols, FlexRay is expected to become the communication backbone for future automotive systems. In this paper, we identify single points of failure in the FlexRay protocol by injecting a total of 135,600 single-bit transient faults into all accessible registers of the FlexRay communication controller. The results showed that about 1.2% of all injected faults caused the controller to freeze immediately. Based on these results and... 

Loop restoration scheme (LRS) is a special feeder automation (FA) scheme, which is used by utilities to improve distribution system reliability. The LRS is controlled and managed by its automatic control system (ACS). The impacts on distribution system reliability indices of implementing LRS mainly depend on the type of its ACS. Two common types of ACS of LRS are presented and used in this study. Successful operation of ACS is dependent on the protection and automatic control functions of switching devices of LRS. Different failure modes of these switching devices can therefore affect the procedure of ACS in fault detecting, isolating and service restoration. The impacts of failure of... 

Uncertainty and variability in the supply sector of renewable-penetrated power systems is becoming a new challenge for secure operation of these systems which if not responded properly may cause large amounts of load and supply curtailments. To meet this challenge, some ISOs recently have employed a new product named Flexible Ramping Product (FRP) into their markets which enhances the capability of the system to overcome such uncertainties by reserving additional ramp rates. In this regard, a new framework for implementing FRP in real-time market is proposed here. The proposed framework provides a proper opportunity for participation of thermal generating units in procuring FRP requirements.... 

This paper presents a modified particle swarm optimization (MPSO) algorithm for solving the optimal power flow (OPF) problems. The main distinction of this approach is in using particle's worth experience in stead of the best previous experience. The proposed approach is evaluated on the IEEE 30-bus test system which minimizes the total fuel cost considering operational constraints such as power flow equations, transmission flow limits, bus voltages and reactive power of generators. The results obtained using the proposed approach are compared with results of other optimization methods  

In the new environment of power system, generating units dispatch problem plays an important role inasmuch as it is used to clear power market transactions. That is, market operator solves an optimization problem in order to find the energy and capacity reserve quota of each generating units participating in the power market. There are different techniques for solving this problem which differ in many aspects, including the objective function, optimization algorithm, and feasibility, so using an efficient technique is vital. In the real competitive electricity market, the components of generating units dispatch problem are faced with the uncertainties; therefore, due to the presence of... 

This paper presents a method for the optimal allocation of Distributed generation in distribution systems. In this paper, our aim would be optimal distributed generation allocation for voltage profile improvement and loss reduction in distribution network. Genetic Algorithm (GA) was used as the solving tool, which referring two determined aim; the problem is defined and objective function is introduced. Considering to fitness values sensitivity in genetic algorithm process, there is needed to apply load flow for decision-making. Load flow algorithm is combined appropriately with GA, till access to acceptable results of this operation. We used MATPOWER package for load flow algorithm and... 

This paper addresses the midterm preventive maintenance outage scheduling problem of thermal generating units which is becoming increasingly important due to the aging of power generation fleet. In this context, a novel midterm preventive maintenance outage scheduler is proposed based on decision tree and mixed integer linear formation which explicitly considers the thermal units aging momentum in terms of failure rate. This allows the system operators to determine the thermal units' maintenance outage window based on the cost/benefit analysis of preventive maintenance tasks while optimizing the time interval between consecutive maintenance tasks. Additionally, the division of the year-long... 

Automation is acknowledged by distribution utilities as a successful investment strategy to enhance reliability and operation efficiency. However, practical approaches that can handle the complex decision-making process faced by decision makers to justify the long-term financial effects of distribution automation have remained scarce. An automated and remote-controlled sectionalizing switch play a fundamental role in an automated distribution network. This paper introduces a new optimization approach for distribution automation in terms of automated and remotely controlled sectionalizing switch placement. Mixed-integer linear programming (MILP) is utilized to model the problem. The proposed... 

This paper investigates the effects of service quality regulation on investing in distribution automation. Among different regulatory instruments for quality regulation, the Reward-Penalty Scheme (RPS) has been selected to evaluate the effect of monetary incentive on behavior of Electric Distribution Utility (EDU) for service reliability. By implementing different automation strategies, the value of enhancing reliability indices and consequently the value of rewards and penalties are calculated for each strategy. For achieving to more realistic outcome, ten years horizon is considered. Furthermore, in the calculation of reliability indices, the time varying failure rate of components is... 

Increasing the social welfare and achieving real competitive markets are the main purposes of consumers participation in electricity markets. Hence, Demand Response Programs (DRPs) have been designed to consider the consumers participation. One of these programs named Emergency Demand Response Program (EDRP) is based on consumers' responses to high electricity prices and to the incentives that are paid by Independent System Operators (ISOs) in the critical hours. In this paper, a model has been proposed for EDRP participation in the Stochastic Security Constrained Unit Commitment (SCUC) program. Both the spinning reserve and the demand side reserve, which is modeled as EDRP, are taken into... 

This paper presents a fuzzy based modified artificial bee colony (MABC) algorithm to solve discrete optimal power flow (OPF) problem that has both discrete and continuous variables considering valve point effects. The OPF problem is formulated as a multi-objective mixed-integer nonlinear problem, where optimal settings of the OPF control variables for simultaneous minimization of total fuel cost of thermal units, total emission, total real power losses, and voltage deviation are obtained. The proposed approach is applied to the OPF problem on IEEE 30-bus and IEEE 118-bus test systems. The performance and operation of the proposed approach is compared with the conventional methods. The... 

In this paper, Bayesian Network (BN) is used for reliability assessment of composite power systems with emphasis on the importance of system components. A simple approach is presented to construct the BN associated with a given power system. The approach is based on the capability of the BN to learn from data which makes it possible to be applied to large power systems. The required training data is provided by state sampling using the Monte Carlo simulation. The constructed BN is then used to perform different probabilistic assessments such as ranking the criticality and importance of system components from reliability perspective. The BN is also used to compute the frequency and... 

Open access to transmission networks as well as designing an efficient cost allocation method are the key points that provide free competition for participants in power market. Restructuring in power systems has created new challenges which emphasize the development and fairness of economical criteria such as pricing of different services in market environment. Besides, the charge of network usage is a controversial subject, itself. To address this problem, many methods for transmission line cost allocation have been proposed. Amongst them, MW-Mile methods are based on the extent of use concept. Inability to take various fixed together with variable imposed costs into account can be...