Percorrer por autor "Khojasteh, Meysam"
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- Energy-constrained model for scheduling of battery storage systems in joint energy and ancillary service markets based on the energy throughput conceptPublication . Khojasteh, Meysam; Faria, Pedro; Vale, ZitaAmong different local renewable resources, using battery energy storage (BES) has grown more than other technologies. The main reasons for this growth are flexibility and schedulability of BES. The fast ramp-rate of BES systems provides the opportunity of effective participation of these resources in the regulation ancillary service. However, continuous charging and discharging cycles of BES could decrease its lifetime and the expected profit, consequently. Therefore, the lifespan is a crucial parameter that shall be considered in the scheduling of BES. In this paper, an energy-constrained model is proposed for the scheduling of BES in joint energy and ancillary service markets. Moreover, the Energy Throughput (ET) concept is proposed for modeling the lifetime in the short-term scheduling strategy. In the proposed strategy, the uncertainties of energy prices in energy and regulation markets are modeled by Robust Optimization (RO) methodology. The scheduling problem is linearized and formulated based on the mixed-integer linear programming (MILP) method. The proposed model determines the optimal scheduling of BES based on the profit maximization, operational constraints, lifespan, and the defined risk level. Finally, the performance of model is evaluated vie case study results.
- Optimal strategy of electricity and natural gas aggregators in the energy and balance marketsPublication . Khojasteh, Meysam; Faria, Pedro; Lezama, Fernando; Vale, ZitaThis paper presents a stochastic two-stage model for energy aggregators (EAs) in the energy and balancing markets to supply electricity and natural gas to end-users equipped with combined heat and power (CHP) units. The suggested model takes into account the battery energy storage (BES) as a self-generating unit of EA. The upper and lower subproblems determine the optimal energy supply strategy of EA and consumption of consumers, respectively. In the lower subproblem, the McCormick relaxation is used to linearize the cost function of the CHP unit. To solve the proposed model, the two-stage problem is transformed into a linear single-stage problem using the KKT conditions of the lower subproblem, the Big M method, and the strong duality theory. The performance and efficiency of the proposed model are evaluated using a case study and three scenarios. According to the simulation results, adding CHP units to the energy-scheduling problem of BES-owned aggregators increases the profit of EA by 5.96% and decreases the cost of consumers by 1.57%.
- Primary Frequency Control Ancillary Service in Distribution Network by Coordinated Scheduling of Wind Power and Demand ResponsePublication . Khojasteh, Meysam; Faria, Pedro; Vale, ZitaFrequency is the main parameter that reflects the stability of power system, and mismatches between generation and consumption. Increasing the penetration level of renewable energy resource in distribution network, and their noticeable participation level to provide the required electricity lead to a new challenge for the distribution system operators (DSO). The variable nature of renewable resources is inevitable, and this uncertainty can lead to instability of power systems. Therefore, DSO shall use more flexible and schedulable resource to maintain the security of network in the acceptable level. In this work, Demand response (DR) program is proposed as the backup resource for compensating the wind power uncertainty in primary frequency control (PFC). The proposed model specifies the required capacity of DR resource to maintain the frequency of grid in the allowable region, based on the uncertainty of wind generation. The performance of proposed model will be investigated by a case study.
- A robust model for aggregated bidding of energy storages and wind resources in the joint energy and reserve marketsPublication . Khojasteh, Meysam; Faria, Pedro; Vale, ZitaThe high reliability and flexibility of Battery Energy Storage (BES) resources in comparison with other renewable technologies promote the development of this technology in smart grids. The fast response of BES to load variations could help the power system operators to maintain the balance of generation and consumption in real-time, and improve the flexibility of the smart grid, effectively. In this work, a new model is presented that determines the aggregated scheduling of BES and Wind Power Resource (WPR) in the joint energy and reserve markets. To evaluate the performance of BES in different markets, the proposed model is divided into day-ahead and real-time planning horizons. According to market prices, ramp rates, marginal costs, and technical constraints of units, the optimal participation levels in different markets are determined. The deployed power in real-time and wind power are considered as the uncertain parameters and the Robust Optimization (RO) framework is proposed to manage the related financial risk based on the worst-case realizations of uncertain parameters. The robust strategy is formulated based on the Mixed Integer Linear Programming (MILP) technique, which can be solved via the branch-and-bound method. Finally, the performance and effectiveness of the model are analyzed via different case studies. Simulation results show that the day-ahead and real-time markets are the best options for buying and selling the energy of BESs, and participation in the reserve market and regulation service increases their profit, significantly. Furthermore, the expected profit greatly depends on the risk preferences of decision-makers, and reducing the variation interval of wind generation by 40 % leads to an increase of 74.65 % in revenues.
- Scheduling of Battery Energy Storage and Demand Response Resource in Balancing Ancillary ServicePublication . Khojasteh, Meysam; Faria, Pedro; Vale, ZitaNowadays, benefits and advantages of renewable energies are clear for everyone. Lower cost of these resources (in compare with non-renewable resources), global demanding for the clean energy, limitations of fossil fuel resources, and so on, increase the popularity of renewable energies in power systems. However, the main problem is that the wind and solar power as two cheapest and biggest resources of renewable energy are variable, un-dispatchable, uncontrollable. Every change in the forecasted values of these resources could disturb the balance of generation and consumption in the electricity power network, which can lead to the instability of grid. Therefore, the flexibility of network shall be increased to neutralize the fluctuations of renewable resource. The Battery Energy Storage (BES) as the trusted and reliable energy resource can play a crucial role to maintain the flexibility of grid by instantaneous response to supply and demand variations. However, some constraints of BES such as minimum charge and discharge times, capacity, rate of charge and discharge could limit the generation/consumption of this resource in the real-time balancing. This paper provides a model for scheduling of BES and shifting demand response (SDR) in balancing ancillary service to improve the flexibility of grid. SDR program is proposed as the backup resource to cover the limitations of BES and improve the flexibility of grid. The objective function of proposed model is minimizing the real-time energy supply cost. The proposed model is formulated based on mixed integer linear programming (MILP) methodology. Moreover, the performance and advantages of the proposed model are investigated via a case study.
- Scheduling of battery energy storages in the joint energy and reserve markets based on the static frequency of power systemPublication . Khojasteh, Meysam; Faria, Pedro; Vale, ZitaBy using the battery energy storage (BES) as a fast, reliable, and controllable resource, the system operator can compensate for power mismatches via changing the generation and consumption in discharging and charging modes. However, BES could decrease the inertia of the grid and endanger the security of the system. Therefore, system operators require a scheduling model that takes into account both security and economic issues. This paper presents a linear model for the optimal scheduling of synchronous generators and BESs in the joint energy and reserve markets, based on the constraints of primary and secondary frequency services. In the proposed model, the technical limitations of synchronous generators and BESs, the frequency limitation of the grid, rate of change of frequency (RoCoF) of generators, and the RoCoF of the grid are considered as constraints of the optimization problem. Accordingly, the optimal scheduling of the resources is determined in a way that ensures the security criteria of the system are not violated after the contingency. The effectiveness of the proposed strategy is demonstrated by four case studies. Simulation results show that increasing the battery capacity by 4.68% of the total capacity of the system reduces the total frequency reserves, and total costs of the system by 13.21 and 2.96%, respectively. Consequently, system operators can reduce total operating costs and provide adequate security by deploying BESs.