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The operation of DC-AC converters in most of researches is considered ideal and balanced but in practical applications no ideal and unbalanced cases must be considered. For instance semiconductor switches of a converter may have differences with together or switching circuit in an inverter may be unbalanced. This unbalance can produce additional harmonics such as even harmonics. This additional harmonics can cause many problems. For precise investigation of these harmonics, a model of inverter based on switching function model is presented in this paper. With this model, analytical relations of harmonics in unbalanced condition are obtained. This model is simple but precisely can show the effect of unbalance in switching of inverters. Analytical results for harmonics in unbalanced conditions in inverter switching are examined by MATLAB and PSCAD softwares.

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In this paper, a new structure for quasi-Z-source inverters based on the combination of switched inductors and transformers is proposed. In the proposed inverter, the high voltage gain is achieved by increasing the ratio of the transformer and the number of switched inductor cells. For proposed structure, the principles operation and calculations of voltage gains and average value of the voltage across the capacitors are provided. Power losses of the proposed structure are calculated and the efficiency comparison between the proposed and other structures is given. To determine the advantages and disadvantages of the proposed inverter, the comprehensive comparison between the proposed and conventional topologies is given. To prove the correctness operation of the proposed inverter, the simulation results in PSCAD/EMTDC are used.

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In this paper, a soft switching buck dc/dc converter applicable for fuel cell has been analyzed and the complete details of designing have been presented. Reduction in switching losses and the elimination of voltage/current stresses of the switches are the major advantages of the aforementioned converter. In this converter, the switches are to be ON under zero voltage and zero current conditions, whereas they are to be OFF under zero voltage condition. This converter can be used in high switching frequency. In this paper, the principles of the performance, full details of the analyses of conduction modes, and designing approach have been presented. The performance and correct operation of the converter are validated by the experimental and simulation in PSCAD/EMTDC software.

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In this paper, a non-isolated three-port zero voltage switching bidirectional dc-dc converter without input current ripple. Some advantages of proposed converter are zero voltage switching of main switches, zero current switching of auxiliary switches. By using two active snubbers, it is possible to reduce circulating current and conduction losses. Free ripple condition of input currents is obtained by using coupled inductors in any stages that it reduces size of converter. The proposed converter can be used in boost, buck and buck-boost operation mods. If all of low voltage sources are equal or less than high voltage source, it is possible to increase the number of input sources to as a kind of -port converter. Finally, the zero voltage and zero current switching of switches and ripple free input currents of the proposed dc-dc converter is verified thruogh the simulation results in PSCAD/EMTDC software.

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Energy hub concept has provided new opportunities in energy management scope. Additionally, largely implementation of renewable energy resources has posed strict challenges in energy systems coordination issue. Probabilistic outputs of renewable energy sources make the energy provision coordination so complicated, in the regions where their penetration is high. Energy storage system can be proposed as a solution for mentioned problem. Power to gas units as an electrical energy storage can store the electrical energy in natural gas grid. This paper has focused on stochastic optimization of renewable based networked hubs in the presence of power to gas unit with economical target. Power to gas unit’s direct hydrogen injection and hydrogen tank facilities have been considered in this paper, as well. This paper demonstrates that, power to gas unit can participate positively in network cost and renewable energy curtailment reduction, considerably. 

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Abstract: Frequency load management is a critical challenge in the field of engineering and power system operation. This study introduces a new approach to address this issue using the Particle Swarm Optimization (PSO) algorithm. By employing a multi-objective cost function, this method optimizes the benefits of state feedback matrix. Additionally, the proposed cost function strategically places the closed-loop system poles within a defined range to accelerate frequency stability and minimize power transfer differentials between regions. To minimize the specified cost function, an optimal teaching-learning-based optimization strategy is adopted. Furthermore, the integration of fuzzy logic techniques for combining essential objective functions is recommended. The evaluation of the proposed method involves applying the controller to a two-area power system while considering governor saturation constraints and comparing the results with those of a traditional PI controller. Simulation results emphasize the effectiveness of the proposed approach, demonstrating improvements in system features such as settling time and peak response time.

 

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This article presents an innovative three-stage strategic framework for the effective cooperation of home microgrids in interconnected electricity and heat networks. The framework aims to increase the competitiveness of microgrids in the energy market. A two-level optimization model is used for optimal management of electrical and thermal energy, which includes demand management strategies to maximize system profit. The high-level model maximizes the profit of the network operator and the low-level model minimizes the cost of electricity supply to microgrids. To solve this model, a multi-stage stochastic programming approach based on particle swarm optimization algorithm is proposed. The simulation results show a significant reduction in market prices by approximately 36%, a 47% increase in responsive load consumption, and a tripling of local generation. These findings indicate the potential of the proposed approach in increasing the profit of all participants and improving energy management in cooperative microgrids.