Sharif Digital Repository

In this study, a supply chain model consisting of a single product, one supplier and one retailer is considered. Transportation times are constant and demands at the retailer are assumed to be generated by a stationary Poisson process. Demands not covered immediately from inventory are backordered. The retailer carries inventory and replenishes stock according to a (Q, R) policy. The supplier has online information about the demand at the retailer and uses this information to replenish its stock. The order size at the supplier is a multiple integer to the retailer's order size. Considering order costs for the retailer and the supplier, we derive the exact cost function for this inventory... 

Owing to wind power inherent characteristics and technical constraints of power systems operation, a considerable amount of wind energy cannot be delivered to load centers and gets curtailed. Transmission congestion together with temporal mismatch between load and available wind power can be accounted as the main reasons for this unpleasant event. This paper aims to concentrate on the wind energy curtailment for which it provides a combinatorial planning model to maximize wind power utilization. Jointly operating the wind power generation system with pumped hydro energy storage (PHES), the planning procedure tries to reach schemes with the minimum level of wind energy curtailment as well as... 

In the past decade, distribution network operators have been broadly engrossed toward automated distribution networks. The operators acknowledge network automation as an efficient investment toward a better service reliability. This paper aims to provide a new long-term cost/benefit analysis for an optimal level of distribution network automation. In the analysis, reduction in customer outage cost is considered as the benefit of implementing automation systems with capital investment, and annual operation and maintenance costs. In the Finnish regulation model, there is a special incentive based on customer outage cost reduction. As the main contribution of this paper, the impact of earth... 

Customers participating in demand response programs known as active customers provide significant flexibility in demand, thereby causing a meaningful reduction in customer interruption cost (CIC) during critical periods. This letter illustrates the impact on the amount of CIC of active customers' flexible demand realized by smart grid technologies. The focus of this letter is on residential electricity use. The study is applied to actual data from Kainuu, Finland  

The integration of high-voltage direct-current (dc) transmission lines in conventional alternating-current (ac) systems would affect the indirect measurement of phasor measurement unit (PMU) devices since the concept of phasors would not correspond to dc transmission circuits. The optimal PMU placement problem in ac/dc systems subjected to the system observability is presented in this paper by applying a mixed-integer programming model. In practice, the cost of each PMU is variable as a function of PMU measurement channels. This attribute is incorporated in the proposed model as well. In addition, the number of PMU measurement channels is deemed to be technically limited; thus, the common... 

Application of residential demand response (DR) programs are currently realized up to a limited extent due to customers' difficulty in manually responding to the time-differentiated prices. As a solution, this paper proposes an automatic home load management (HLM) framework to achieve the household minimum payment as well as meet the operational constraints to provide customer's comfort. The projected HLM method controls on/off statuses of responsive appliances and the charging/discharging periods of plug-in hybrid electric vehicle (PHEV) and battery storage at home. This paper also studies the impacts of different time-varying tariffs, i.e., time of use (TOU), real time pricing (RTP), and... 

This paper proposes an operation framework for incorporating time-varying electricity rates into day-ahead distribution system operation. The day-ahead distribution system operation problem is formulated as a mixed-integer linear programming (MILP) model, in which profit of the distribution system operator (DSO) from serving local loads is maximized. The impact of time-varying electricity rates on local loads is determined based on the estimated price elasticity of the customers and the historical consumption data. The customers' consumption behaviors in the absence of time-varying electricity rates are captured in terms of the customer baseline load (CBL). The proposed model is applied to a... 

Existing real-time pricing (RTP) schemes charge the whole customer's consumption at one highly volatile time varying price, which, in turn, imposes financial risk to participating customers. This paper presents a two-part RTP scheme aiming at efficient distribution system operation while mitigating customers' risk level imposed by volatile RTP prices. Our proposed RTP scheme offers two different RTP price signals. The first RTP price signal is used to charge customer's consumption up to its customer baseline load (CBL) which presents customer's consumption in the absence of RTP signals. The second RTP price signal is announced a day ahead of the actual operation, and can be updated in real... 

Trying to find the most efficient and cost-effective decisions on the maintenance of different component types in power distribution systems is an increasingly challenging concern largely driven by the current financial constraints in distribution utilities worldwide. In regard to deal with this challenge, the paper presents a practical application of the Delphi method and the Modified Analytical Hierarchical Process (MAHP) that can be used to find the most critical component types of the system in order to assist in accordingly allocating the available maintenance budget. The proposed approach involves the experience and knowledge held by experts and the historical empirical performance... 

Demand response (DR) as a key integral part of the future smart grid is gaining a great and still growing focus of attention in nowadays electric power industries. However, many potential benefits of DR, although they have been envisioned to be significant, have not been yet thoroughly and quantitatively investigated. DR provides network operators with the opportunity to mitigate operational limit violations by load modification in place of load shedding when network reliability is jeopardised. This paper aims to comprehensively assess the potential impacts of DR on major attributes of service reliability in a residential distribution network. For doing so, firstly, load profiles for major... 

Planning of distribution networks is usually accomplished using a cost-based conventional model that minimizes the total cost of construction and reinforcement of substations and feeders. The resulted expansion plan designed by this cost-based model is not necessarily the best choice for an electrical distribution company (DISCO) in the nowadays deregulated structure. This happening is mainly due to the fact that the utility seeks to maximize its profit in this competitive environment. On the other hand, this model does not consider the upcoming new challenges ahead of distribution systems, such as smart grid and distribution automation technologies. This paper presents a novel profit-based... 

This letter proposes an analytic framework for achieving an optimal solution for phasor measurement unit (PMU) placement problem. The proposed technique is on the basis of the cost/benefit analysis while long-term economic aspects and existing technical issues are simultaneously accounted for. More deployment of PMU devices would result in more reliable and secure electricity services. The reduction of system risk cost is hence recognized as the benefit associated with the development of wide-area measurement system (WAMS). The optimal number and location of PMUs are determined such that adding more PMUs is no longer beneficial. Two systems are examined to demonstrate the performance of the... 

The business activities of the majority of industrial and commercial customers are dependent on some critical equipments that are susceptible to voltage sag events. This paper aims to propose a novel approach to estimate the financial impacts of voltage sag events on customer operations. The proposed technique is based on the event tree method. Using this approach, it is possible to consider the impacts of operational failure of various sensitive equipments, involved in the customer operations, on the financial losses expected from voltage sag events. A quantitative case study is conducted in the paper to illustrate the applicability of the proposed approach  

A massive focus has recently been made on demand response (DR) programs, aimed to the electricity price reduction, reliability improvement, and energy efficiency. Basically, DR programs are divided into twofold main categories, namely incentive-based programs and price- or time-based programs. The focus of this paper is on priced-based DR programs including consumer responses to the time differentiated pricing. Home load management (HLM) program is designed to control responsive appliances and charging/discharging cycles of plug-in hybrid electric vehicles (PHEVs) by the consumer. Uncertain parameters associated with PHEV, i.e. its departure/travelling time and energy consumption as well as... 

In this paper, by a simple example it is shown that existing market-based criteria alone cannot completely and correctly evaluate the transmission network expansion from market view. However criteria congestion cost (CC) and social welfare (SW) together are able to correctly evaluate transmission network from market view and so they are adopted for the market-based transmission expansion planning. To simply indicate the limits of CC and SW social welfare percentage (SWP) and congestion cost percentage (CCP) are defined. To consider uncertainty in bids of market producers and consumers, and also indeterminacy in the acceptable boundaries of the SWP and CCP and their priorities, fuzzy... 

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... 

The concerns of regulatory authority for the cost efficiency and service quality of distribution utilities has led them to implement monetary schemes, such as penalty/reward mechanism (PRM). PRM provides explicit financial incentives for distribution system operators (DSO) to maintain or improve their efficiency and quality of service. Although the effectiveness of the PRM is proven, analytical tools that can handle the complex decision-making process faced by decision makers to respond to PRM are scarce. This paper presents an approach for distribution system maintenance management in the presence of the PRM. The proposed approach tailors the maintenance plans by taking into account the... 

In a practical power system, automating all the substations is neither affordable nor economically justifiable. On the other hand, the trend for electric power subsidies elimination in some regions, such as Iran, aggravates this situation. To enhance the cost effectiveness of distribution automation system, this paper proposes a novel applicable qualitative-quantitative method using analytical hierarchical process (AHP) to find the optimum placement of remote terminal units (RTU). Entire attempt is to contribute all the crucial technical and practical parameters related to this problem in order to find the most reliable solution. Optimum number of RTUs is determined using the concepts of... 

The deployment of flexible ac transmission system (FACTS) devices, despite miscellaneous benefits and applications, has been restricted mainly due to their large investment costs. Accordingly, the notion of distributed FACTS (D-FACTS) was recently proposed. Distributed static series compensators (DSSCs), as a new member of D-FACTS, are directly clamped to conductors of transmission lines. The possibility of controlling the compensation rate of DSSCs from the control center affords the active control of network power flow. This paper presents a comprehensive reliability model for the DSSC. The model is then reduced and a state-space representation is extracted for a transmission line with a... 

This study intends to develop a comprehensive procedure for evaluating locational value of a wind farm project incorporating reduction in transmission system losses, load delivery point interruption cost and operating cost of generating units. The energy extracted from the wind farm in normal operation condition is considered to replace the energy from fossil-fueled conventional units. In addition, composite system reliability analysis in the presence of wind power is carried out to evaluate total costs associated with curtailed energy at different load points as well as generation of generating units in contingency conditions. System reliability analysis related to large-scale wind farms,...