Sharif Digital Repository

Probabilistic approaches generally base the design and operating constraints on the criterion that the risk of certain events must not exceed preselected limits. Many utilities still prefer to use deterministic techniques owing to the difficulty in interpreting a numerical risk index and the lack of sufficient information provided by a single index. This is especially true in the power system operating domain as existing probabilistic risk indices do not provide any assessment of the capacity reserve available during the course of system operation. A practical way to overcome these difficulties is to embed deterministic considerations into the probabilistic framework in the form of system... 

The growing utilization rate of electric vehicles (EVs) because of their advantages, like environmental pollutant reduction, may bring challenges to power systems for the reason of considerable charging load and random nature of their net load consumption. However, aggregation and coordination of EVs (especially EVs with vehicle-to-grid (V2G) capability) offer new opportunities to grid operators by providing the possibility of charging/discharging cycle control of their batteries. On the other hand, energy storage systems (ESSs) are one of the most applicable distributed energy resources (DERs) with growing penetration level in the last decades. The optimal coordination and schedule of ESSs,... 

Nowadays communication and monitoring systems play an important role in power systems security. However, these systems are exposed to bad data injection through attackers. This paper is aimed to propose a priority order list of attacked buses in order to be fully informed about the attacker decision. To do so, system security is evaluated through two well-known risk indices including under voltage risk index and overloading risk index. A genetic algorithm (GA) is employed to determine the most severe attack for each of the security indices. The effectiveness and accuracy of the proposed model are scrutinized through simulations on the IEEE 30-bus network. The paper reveals that knowing the... 

This paper investigates the main features of the PHEV centralized and decentralized charging control mechanisms, their requirements and also impacts on distribution system performance. A home-based charging control scenario as well as a coordinated charging control algorithm for the charging management of PHEVs is devised in this paper. Both the owner preferences and system operator concerns are taken into consideration in an optimization-based framework. The total network losses and charging costs are set as the constraints to the proposed optimization approach. Various aspects of the two mechanisms are discussed and comprehensively compared by their application on the IEEE 34-bus test... 

This paper investigates the main features of the PHEV centralized and decentralized charging control mechanisms, their requirements and also impacts on distribution system performance. A home-based charging control scenario as well as a coordinated charging control algorithm for the charging management of PHEVs is devised in this paper. Both the owner preferences and system operator concerns are taken into consideration in an optimization-based framework. The total network losses and charging costs are set as the constraints to the proposed optimization approach. Various aspects of the two mechanisms are discussed and comprehensively compared by their application on the IEEE 34-bus test... 

By applying shortest path analysis in stochastic networks, we introduce a new approach to obtain the reliability function of time-dependent systems with standby redundancy. We assume that not all elements of the system are set to function from the beginning. Upon the failure of each element of the active path in the reliability graph, the system switches to the next path. Then, the corresponding elements are activated and consequently the connection between the input and the output is established. It is also assumed each element exhibits a constant hazard rate and its lifetime is a random variable with exponential distribution. To evaluate the system reliability, we construct a directed... 

This paper presents a new framework for multistage expansion planning in active power distribution networks, in which the distribution system operator (DSO) considers active network management by clearing the local energy market at the distribution level. The proposed model is formulated as a bi-level optimization problem, where the upper level minimizes the net present value of the total costs imposed to DSO associated with the investment and maintenance of the network assets as well as the network operation, while the lower level on clearing the local energy market captures the participation of distributed energy resource (DER) owners and demand aggregators to maximize the social welfare.... 

Constraint automata are the first-proposed operational semantics of Reo coordination language. They can be composed not only by all well-defined composition operators of labeled transition systems but also by two new operators. The new operators are joining of constraint automata with respect to their common port names and hiding a port name in all transition labels. The operations of these two extra operators depend on the internal structures of the transition labels, while in the others each transition label is considered as a simple entity. An equivalence relation between transition systems is a congruence relation if the replacement of the components of a model by the equivalent ones... 

Deregulation in power systems has created new uncertainties and increased the previous ones. The presence of these uncertainties, high investment costs, and long period investment return cause the transmission network to remain monopoly and the private investors not being interested in investing in this section. This paper presents a new approach for transmission expansion planning (TEP) in order to maximize private investment absorption. The robust optimization method is used to model the inherent uncertainties associated with the estimated investment cost of candidate lines and the forecasted system load. The genetic algorithm (GA) is, also, utilized as the methodology to solve the... 

Renewable energies as a solution for environmental issues have always been a key research area due to Demand Response Programs (DRPs). However, the intermittent nature of such energies may cause economic and technological challenges for Independent System Operators (ISOs) besides DRPs, since the acceptable effective solution may exceed the requirement of further investigations. Although, previous studies emphasized employing Demand Response and Renewable Energies in power systems, each problem was investigated independently, and there have been few studies which have investigated these problems simultaneously. In these recent studies, authors neither analyzed these problems simultaneously... 

Recently, demand-response (DR) programmes are one of the appropriate tools for energy systems to encourage flexible customers to participate in the operation of energy systems. One of the complex tasks in multi-energy environments is optimal energy flow (OEF) problem of these systems. In this regard, this study investigates the OEF of an integrated electrical, heat, and gas system considering flexible heat and electrical demands. The conventional DR programme has been combined with the demand-side energy supplying management activity by introducing switching concept among input energy carriers. The way of the supplying energy of flexible customer can be changed by switching among input... 

Assessing the operational flexibility of the grid with high penetration of renewable resources remains an issue of critical importance. Operational flexibility insufficiency may bring about two major problems: 1) there may exist no feasible solution for operation under uncertain conditions due to insufficient available flexibility capacity; 2) even if the solution feasibility criterion is ensured, dispatch limitations of the flexible resources may force the system operating point to deviate from the optimal economic point with increased redispatch. In this paper, an optimal uncertainty set at the unit commitment time scale is proposed and characterized as a reliable operational metric. A... 

Recently, power system operators have initiated procurement of a new service in electricity markets named flexibleramping product (FRP). With the main goal of enhancing the grid flexibility, this product can provide a remarkable opportunity foran enhanced short-term profitability. Energy storage systems (ESSs) with high ramping capability can leverage their profitabilitywhen properly participating in this market. This study introduces a stochastic optimisation framework for participation of ESSs inthe FRP market. The proposed model formulates the optimal bidding strategy of ESSs considering the real-time energy, flexibleramp-up and ramp-down marginal price signals and the associated... 

In this paper a fuzzy power controller for a parallel hybrid passenger car is developed in order to minimize its fuel consumption and optimize its components efficiencies. This is done by controlling the engine operating points in its optimal region and maintaining the SoC of batteries and electric motor operating point at the highest possible efficiency. Of course the designed control strategy must be able to obey the driver's commands and achieve the PNGV regulations. The controller implemented in this paper is a Mamdani fuzzy logic controller which takes the batteries SoC, electric motor's speed, ICE speed and the total demanded torque as its input variables and gives the ICE torque as... 

The escalated penetration of wind energy in the electric industry has by large contributed to an intensified uncertainty and variability of the net-load, i.e., the difference between stochastic demand and intermittent supply. In response, some Independent System Operators (ISOs) have recently introduced the Flexible Ramping Product (FRP) to heighten the grid flexibility via effective hosting of the uncertain renewables. This paper suggests a novel framework for optimal FRP provision in real-time markets (RTM) in which the shortage in the RTM ramp capacity is compensated by optimal deployment of day-ahead procured spinning reserve. In the envisioned mechanism, the ISO can deploy specific... 

The inherent complexities of multi-reservoir flood control systems and their operation conditions along with the improvements of optimization methods have led to a positive trend on better development of these models. This trend tends to provide the operators of these systems with more practical solutions. Although optimization models can provide appropriate solutions for operation of multi-reservoir systems, the exact implementation of these solutions in real world is not guaranteed. This arises mainly due to high level risk of flood situation, real time operation constraints, high level uncertainties of inflows that usually are overlooked in optimization models, and so on. These problems... 

Minimization of operating costs is one of the most important objectives of power system operators. To achieve this goal, several optimization problems such as unit commitment and optimal power flow have been introduced. Historically, in these problems, the transmission network has been considered as a static system, i.e., the ability of transmission lines switching is not modeled. On the other hand, it has been shown that transmission line switching can significantly reduce operating costs by the means of topology modification. However, considering this capability, a large number of binary variables are introduced in the objective function, and as a consequence, the computation time will be... 

Power system operation is undeniably affected by system security indications providing system operators with insight into power system status. In this regard, any tampered data would compromise power system security. This paper aims at presenting an approach to scrutinize the impact of cyber attacks on the system security indices. With this in mind, two well-known system security indices representing voltage and loading severities are taken into account. The approach uses genetic algorithm to find the most severe conditions for each security index from financial and technical viewpoints. In the former, bad data injection targets to overestimate security indices resulting in unnecessary... 

Supplying sustainable energy is of a critical prominence nowadays. A main outcome of the galloping development in energy generation technologies is the ability to integrate multi-carrier energy systems that facilitates meeting the fast growth of energy demand. Energy hub is one of the main infrastructures making the incorporation of multi-carrier systems smoother. In this paper, the optimal scheduling problem of an energy hub structure equipped with combined heat and power, boiler, power-to-gas storage, thermal energy storage and electrical energy storage in order to supply power, heat and gas demands is presented. Power to gas is regarded as a new technology that creates a connection... 

This paper presents a new framework for multistage expansion planning in active power distribution networks, in which the distribution system operator (DSO) considers active network management by clearing the local energy market at the distribution level. The proposed model is formulated as a bi-level optimization problem, where the upper level minimizes the net present value of the total costs imposed to DSO associated with the investment and maintenance of the network assets as well as the network operation, while the lower level on clearing the local energy market captures the participation of distributed energy resource (DER) owners and demand aggregators to maximize the social welfare....