Examinando por Autor "Bayat, Mohammad"
Mostrando 1 - 4 de 4
- Resultados por página
- Opciones de ordenación
Ítem A novel Newton-like method with high convergence rate for efficient power-flow solution in isolated microgrids(Wiley, 2023-03) Tostado-Véliz, Marcos; Bayat, Mohammad; Ghadimi, Ali Asghar; Jurado-Melguizo, FranciscoPower-Flow (PF) solution in isolated microgrids has attracted notable attention recently, because these systems present various particularities compared with the traditional PF solution in large meshed transmission networks. In this sense, this paper develops a novel Newton-like PF solver for isolated microgrids. The new proposal is based on the Modified Midpoint method and shows high convergence order with relatively low computational burden. These characteristics bring superior theoretical performance compared with the standard Newton–Raphson (NR) method and other high order techniques, which has been conventionally used. Extensive simulations are performed on various small-, and large-scale benchmark Microgrids under different loading conditions and R/X ratios. Results provided serve to confirm the theoretical features of the developed solver, outperforming the NR technique as well as other recently developed solvers in all the studied systems with acceptable reliability even under high stressed conditions.Ítem Comprehensive enhanced Newton Raphson approach for power flow analysis in droop-controlled islanded AC microgrids(Elsevier, 2022-12) Bayat, Mohammad; Koushki, Masoud Mehrabi; Ghadimi, Ali Asghar; Tostado-Véliz, Marcos; Jurado-Melguizo, FranciscoOne of the essential studies in the planning and operation of a microgrid is Power Flow (PF). Traditional PF methods are not applicable for droop-controlled islanded microgrids due to the absence of a slack bus in the system. The steady state characteristics of the system such as frequency, bus voltages, Distributed Generators’ (DG) output power, and actual loads’ demand are obtained based on the droop characteristics of the DGs, and also, the frequency and voltage dependency of the load. Therefore, in this paper, an Enhanced Newton Raphson (ENR) method is proposed for PF in the droop-controlled islanded microgrids. The proposed method is based on the well-known NR method but with a more comprehensive model that considers different droop schemes (resistive, inductive, and complex), load demand dependency on voltage and frequency, π line model, and shunt compensators. Moreover, a new index for selecting proper droop characteristics for any droop-controlled islanded microgrid is proposed. Five test systems with different scales, topologies, droop control strategies, and various load models are considered to evaluate the performance of the proposed method. The results are compared with the recently developed methods and steady-state results of Time-Domain simulations conducted in PLECS software. The results show that the proposed technique has excellent accuracy with low computational time and can be easily integrated into the currently available power system analysis tools.Ítem Home energy management in off-grid dwellings: Exploiting flexibility of thermostatically controlled appliances(Elsevier, 2021-08) Tostado-Véliz, Marcos; Bayat, Mohammad; Ghadimi, Ali Asghar; Jurado-Melguizo, FranciscoIn off-grid dwellings, proper energy management of different appliances, onsite generators and storage facilities is crucial to meet some monetary goals and environmental premises such as CO2 emissions and diesel consumption reduction. Nowadays, this task may be performed by home energy management systems, which are able to efficiently coordinate the operation of the different home assets to achieve some predefined goals. In such cases, the operation of thermostatically controlled appliances such as heating-ventilation-air conditioning systems, electric water heaters and freezers, plays a vital role as this kind of devices allow certain degree of flexibility. This way, some thermal premises (such as thermal comfort, frozen food conservation or hot water temperature set-point) can be relaxed in order to achieve other complementary goals. This work analyses this aspect by proposing a home energy management model which incorporates flexible operational modes of various typical thermostatically controlled devices. Various results are presented on a benchmark isolated home which counts with a diesel engine as backup generator. Results show that energy generated by the backup generator can be reduced by 15% by operating the thermal-based appliances in a flexible way, while other relevant indicators such as fuel consumption, fuel cost and CO2 emissions can be also improved by 12%. Other relevant aspects such as the impact of the photovoltaic array size and storage capacity are also investigated.Ítem Uncertainty-aware energy management strategies for PV-assisted refuelling stations with onsite hydrogen generation(Elsevier, 2022-09-10) Tostado-Véliz, Marcos; Ghadimi, Ali Asghar; Miveh, Mohammad Reza; Bayat, Mohammad; Jurado-Melguizo, FranciscoOne of the main barriers for the wide penetration of fuel cell electric vehicles is the lack of proper infrastructures for hydrogen transportation that hinders the implantation of refuelling stations. This barrier could be overcome by deploying onsite hydrogen generators based on mature electrolysis and hydrogen storage technologies. This way, the necessity of hydrogen transportation is avoided. In addition, electrolysers can be onsite supplied by means of renewable generators like photovoltaic panels, while the produced hydrogen can also be destined to generate electricity through fuel cells thus obtaining a monetary revenue. Thereby, the economy of the system may be improved in order to make viable this kind of infrastructures. However, the optimal coordination of the different assets is challenging and requires the use of energy management tools to pursue the optimal performance of the installation. In this kind of infrastructures, the energy management problem is performed under substantial uncertainties; moreover, these unknown parameters have a very different character. Thus, while energy pricing and renewable generation can be forecasted using conventional techniques, refuelling demand is highly unpredictable. To this end, this paper proposes a novel stochastic-interval model for the optimal scheduling of photovoltaic-assisted refuelling stations. The new proposal uses interval notation to model the inherent uncertainty of renewable generation and energy pricing, while the vehicle demand is modelled using a more suitable approach based on scenarios. In this regard, a comprehensive stochastic model for fuel cell electric vehicles is developed, which is based on reported driving behaviour and common characteristics of commercial vehicles. To solve the problem subjected to uncertainties, an iterative solution methodology is developed which allows adopting risk-seeker and risk-averse operational strategies. A case study is analysed to validate the new proposal and discussing the importance of the different economic activities that can be exploited in refuelling stations. Results reveal the importance of selling energy to the grid in order to complement the revenues obtained from refuelling; however, this process is highly impacted by uncertainties and the operational strategy, observing variations up to 50% in the total profit depending on the strategy adopted.