Sharif Digital Repository

Owners of electric vehicles (EVs) can offer the storage capacity of their batteries to the operator of a microgrid as a service called vehicle-to-grid (V2G) to hold the balance between supply and demand of electricity, particularly when the microgrid has intermittent renewable energy sources. Literature review implies that V2G has economic benefits for both microgrid operator and EV owners, but it is unclear how these benefits are divided between them. The challenge grows when the policy makers rely on the V2G revenue as an incentive for expanding the penetration of EVs in the automotive market. This paper models the interaction between microgrid operator and EV owners as a bargaining game... 

This paper investigates the role of parking lots in improving the reliability of renewable-based distribution systems, through provision of vehicle-to-grid (V2G) programs during outage events. In this regard, municipal parking decks are viewed as distributed energy storage systems and the amount of available energy from these units in random contingency events is probabilistically modeled for reliability studies. Appropriate stochastic models are also introduced to capture the volatility and intermittency of renewable sources. Moreover, it is discussed that how the adopted outage management scheme (OMS) in contingency events can affect the reliability level of customers. In response, several... 

This paper aims to analyze Iran's long-term power sector development from economic, environmental, social, and sustainable perspectives. For this purpose, a linear programming model is developed, which includes three objective functions: minimization of costs, minimization of CO2 emissions, and maximization of created jobs. To provide a sustainable plan, analytical hierarchy process is employed to allocate expert-based weights to the objective functions. Moreover, to support the decision-makers, Pareto-optimal alternatives are explored by varying the weights of objectives. The multi-objective model is solved by applying a weighted method based on fuzzy membership functions. The results show... 

In this paper, a hierarchical frequency regulation system is presented for real-time operation of the electrical grids. It includes a decentralized transactive energy system for clearing transactions of producers/consumers in real-time. The proposed system is implemented in a distributed fashion with small data communication requirement. It is proved that the proposed transactive energy system converges to the optimal power flow (OPF). An iterative method for optimizing control parameters of the proposed hierarchical frequency regulation system is also given. The proposed method is developed for high penetration of renewable energy sources (RESs) as the sizes, locations, and uncertainties of... 

Energy innovation is a key requirement to limit global warming and tackle climate change in the years to come. A better understanding of the public R&D mechanism is likely to improve allocation of resources for energy innovation. Thus, the present paper evaluates the impacts of public R&D and knowledge spillovers on the development of renewable energy sources. To achieve this goal, knowledge flow has been modeled as a function of public R&D expenditures, cumulative knowledge stocks and knowledge spillovers. To show the application of the model, the Nordic countries as one of the pioneers in renewable technologies have been chosen. Results show the cumulative knowledge stock will increase to... 

In this study, optimal offering strategy problem of a virtual power plant (VPP) as a price-maker player in day-ahead frequency constrained electricity market is presented. The optimal offering strategy problem is modelled as a bi-level optimisation problem. In the upper-level problem, the total profit of VPP is maximised. In the lower-level problem, the clearing conditions of frequency constrained electricity market are modelled. The proposed bi-level optimisation problem is reformulated as a mathematical programming with equilibrium constraints (MPEC) problem by using Karush-Kuhn-Tucker conditions. Then, the proposed MPEC problem, which is non-linear and hard to solve by commercial solvers,... 

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... 

In this paper, the problem of frequency-constrained electricity market (FCEM) is modeled in the presence of renewable energy sources (RESs) and price-maker players by using equilibrium problem with equilibrium constraints formulation. It is worth mentioning that due to the intermittency of RESs, the FCEM problem in the presence of price-maker players becomes more imperative as stability of power system frequency is a public good and the free-rider problem arises. Moreover, as players of FCEM do not know their rivals' objective functions, the problem is modeled based on Bayesian game theory. The FCEM problem is converted into a game of complete but imperfect information under the common prior... 

In this paper, a robust distribution system expansion planning (DSP) approach is presented to supply the load growth locally and move toward nearly zero energy local distribution areas (LDAs). In the proposed approach, a distribution system operator (DSO) is responsible for secure and optimum operation of LDAs. Therefore, investors on distribution system upgrades use this approach to maximize the profit on investments by determining the installation year of new distribution feeders and energy resources, distributed energy resource (DER) placements and sizes considered by corresponding DSOs. The accurate AC power flow solution is used and mathematical methods are developed to model the DSP as... 

Photovoltaic-electrolyzer systems are one of the most promising alternatives for obtaining hydrogen from a renewable energy source. Determining size and the operational conditions are always a key issue while coupling directly renewable electricity sources to PEM electrolyzer. In this research, the multi objective optimization approach based on an imperialist competitive algorithm (ICA), which is employed to optimize the size and the operating conditions of a directly coupled photovoltaic (PV)-PEM electrolyzer. This allows the optimization of the system by considering two different objectives, including, minimization of energy transfer loss and maximization of hydrogen generation. Multi... 

With the proliferation of intermittent renewable energy sources, power systems need to withstand an increasing number of disturbances that may affect system frequency. In this paper, we focus on the effects of high penetration level of wind turbine-generators (WTG) on the power system operational planning from the frequency point of view. Specifically, an exact formulation for the minimum frequency calculation is presented to increase accuracy and speed of analyses. Then, the effect of WTG's frequency response on the power system frequency stability is investigated to compute the maximum acceptable generation outage as a function of penetration level. Finally, as an application to power... 

Power systems have been undergoing significant restructuring as a result of increasing independently operated local resources. Consequently, new entities, i.e. microgrids (MGs), are developed, which facilitate the integration of local resources, specifically renewable energy sources (RESs), into the operation of power systems. Despite many benefits, the integration of RESs could cause severe rampings in the net-load, which would challenge the reliable operation of the system. Therefore, it seems essential that flexible local resources in an MG should be employed to provide flexibility services to the main grid, thus ensuring that ramping in the MG's net-load would meet the ramping capability... 

Introduction of renewable energy sources (RESs) and independently operated multi-microgrid (MMG) systems have led to new issues in the management of power systems. In this context, uncertainty associated with RESs as well as intense ramps inflicted on the network called system flexibility constraints have raised new challenges in power systems. The new condition necessitates the implementation of novel frameworks that enable local system operators to efficiently manage the available resources to cope with the flexibility-ramp constraints. Moreover, the new framework should facilitate energy management in a system with an MMG structure considering uncertainty of RESs. Consequently, in this... 

Restructuring and privatization in power systems have resulted in a fundamental transition of conventional distribution systems into modern multi-agent systems. In these structures, each agent of the distribution system would independently operate its local resources. In this regard, uncertainties associated with load demands and renewable energy sources could challenge the operational scheduling conducted by each agent. Therefore, this paper aims to develop a distributed operational management for multi-agent distribution systems taking into account the uncertainties of each agent. The developed framework relies on alternating direction method of multipliers (ADMM) to coordinate the... 

This paper introduces a day-ahead clearing model for the simultaneous energy and ancillary services market in high penetration of renewable energy sources (RESs) considering fast-start generators’ behaviors as non-spinning reserve providers. For managing the uncertainties of RESs, the system operator takes the advantages of the stochastic model of security-constrained unit commitment (SCUC) problem considering plausible scenarios. The non-convexities due to the startup costs, minimum power outputs, and commitment variables make the stochastic SCUC problem and market-clearing non-convex. Meanwhile, with traditional market-clearing methods for energy and ancillary services based on marginal... 

Growing interest in the intermittent renewable energy sources may jeopardize the flexibility of power systems. In order to improve the flexibility of modern power systems, the surplus electricity generated by renewable sources can be deployed into several carriers, such as natural gas and heating energy via power-to-gas (PtG) and power-to-heat (PtH) technologies. This paper proposes an optimal daily energy management model of residential energy hubs integrated with power-to-X technologies. The proposed energy hub is incorporated with PtG, PtH, combined heat and power (CHP) facilities, and thermal storage to meet the required electrical, gas, and heating demands. In order to capture the... 

This paper provides a general methodology for evaluating the reliability of microgrids embedding conventional and renewable energy sources (RESs), as well as energy storage systems (ESSs). The developed reliability assessment model is then leveraged to investigate the impact of different resource scheduling methods on the reliability. The technique applied in this article to assess microgrid reliability is based on the sequential Monte Carlo simulation. In this approach, the coincidence of faults is considered, aside from the annual generation pattern of RESs, i.e., wind and photovoltaic, and the network load profiles. For the sake of considering priority of the microgrid loads, two... 

With the advent of small-scale heat and electricity producers in distribution energy systems, the interdependencies between energy carriers have been increased. Moreover, the rapid deployment of micro CHP, electric heat pumps, electricity-to-heat appliances etc., calls for new local market frameworks to be employed in distribution energy systems. In response, this paper presents a new energy market framework based on the concept of peer-to-peer negotiations to facilitate energy transactions between agents at the distribution level while addressing the interdependencies between different energy carriers. Moreover, linear optimization problems are proposed to investigate the optimal strategies... 

Transmission lines congestion has recently been a vital challenge in power systems operation due to the intermittent outputs of renewable energy sources (RES). Therefore, an efficient transmission congestion management (TCM) method should be defined to deal with the congestion issue. This paper aims to propose a simultaneous linearized two-stage TEP-BESS co-planning optimization model to relieve transmission lines congestion. In doing so, a novel TCM structure is suggested in a pool-based deregulated data-driven optimal power flows (D-OPF) by the computationally effective min-max regret method to consider future scenarios of generating units and demanded loads. To improve the efficiency of... 

Hydrogen is considered to be the fuel of the future. It is a cleaner alternative to the fossil fuels we consume every day. Of all the different hydrogen production pathways that exist, producing the gas by utilizing the power generated by renewable energy sources has been a topic of interest for many researchers across the world. The following work focuses on minimizing the energy loss by optimizing the size and the operating conditions of an electrolyzer directly connected to a photovoltaic (PV) module at different irradiance. The hydrogen, in the proposed system, is produced using a proton exchange membrane (PEM) electrolyzer. A nonlinear method is considered, because of the complexity of...