Power
Ramin Arjmandzadeh; Mahdi Banejad; Ali Akbarzadeh Kalat
Abstract
In conventional power systems, most of the power is produced by synchronous generators in the electric grid that have heavy and rotating rotors. As a result, there is an inherent inertia in the rotor of these generators. The presence of inertia in the grid prevents sudden frequency changes during imbalance ...
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In conventional power systems, most of the power is produced by synchronous generators in the electric grid that have heavy and rotating rotors. As a result, there is an inherent inertia in the rotor of these generators. The presence of inertia in the grid prevents sudden frequency changes during imbalance situations, thus, the frequency stability of the grid is maintained. Today, with the increase of renewable energy sources that are usually connected to the network by power electronic equipment. Such resources do not have rotating materials, therefore, the overall inertia of the grid decreases and the stability of the system deteriorates. To solve the problem of lack of inertia in the power electronic-based grid, the notion of the virtual synchronous generator (VSG) technology has been introduced in recent years. This technology can imitate the behavior of traditional synchronous generators for inverters connected to the grid. In this way, the inverters connected to the grid act like a synchronous generator during imbalance. One of the problems associated with the converters-based microgrid is the existence of DC deviations and additional harmonics, which disrupt the work of the converters. Therefore, in this article, a third-order generalized integrator (TOGI) -based VSG for grid-connected inverters is employed so that the system stability is maintained in the conditions of additional harmonics and DC deviation. To show the effectiveness of the proposed method, time domain simulations have been performed in Simulink/MATLAB software. The results of the simulation verify the performance of the proposed method.
Power
Ali Morsagh Dezfuli; Mahyar Abasi; Mohammad Esmaeil Hasanzadeh; Mahmood Joorabian
Abstract
The utilization of distributed generation (DG) in today's power systems has led to the emergence of the concept of microgrids, in addition to changing the mode of generating and supplying the energy required for network electrical loads. When a microgrid operates in the island mode, energy generation ...
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The utilization of distributed generation (DG) in today's power systems has led to the emergence of the concept of microgrids, in addition to changing the mode of generating and supplying the energy required for network electrical loads. When a microgrid operates in the island mode, energy generation sources are responsible for controlling the microgrid’s voltage and frequency. As the microgrid frequency is proportional to the amount of power generated by the DG, the microgrid requires a precise power-sharing strategy. Considering that DGs do not usually have stable output power despite the importance of power stability, the present paper addresses the voltage and frequency control of an islanded microgrid by considering the power generation uncertainties caused by disturbances and the varying power output of DGs. Given that the disturbance on the first DG's input current is 0.2 A, which is approximately 2.2% of the steady-state value, a simulation was performed, and it was observed that the maximum voltage variation of each bus in the worst case was 0.59% for the first bus and 0.53% for the second bus, which means that the controller could control the voltage and frequency values within the permissible range. If the controller is not used, the change in the frequency of each bus will be 10 times, and the voltage change will be 5 times as great as that of the case the controller is used.
Power
Narges Yousefi; Mahmood Joorabian; Mahyar Abasi
Abstract
An obstacle in managing economic dispatch is the integration of diverse factors such as pollution and heat. By introducing the price penalty coefficient, this class of two-objective problems is transformable to a single-objective form. The formulation considers various practical constraints of the system, ...
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An obstacle in managing economic dispatch is the integration of diverse factors such as pollution and heat. By introducing the price penalty coefficient, this class of two-objective problems is transformable to a single-objective form. The formulation considers various practical constraints of the system, including non-smooth cost functions, the balance of production, demand, and losses, and the limitation of power generation by active generators. One of the fundamental difficulties in tackling these types of complex problems lies in the algorithms and solvers employed to identify optimal solutions for a range of operation problems. The rain optimization algorithm (ROA) has been utilized in this paper. ROA is derived from the inherent tendency of raindrops to seek out the lowest areas on the earth's surface. This algorithm possesses exceptional efficacy in resolving problems characterized by stringent constraints and is adept at circumventing local optima. To validate the proposed method for cost and emission reduction, the scheme under consideration has been developed using software on standard systems. The implementation of the scenarios has revealed that the limits of the power system have led to a decrease in the overall generation cost of fossil fuel generation units. In this article, the ROA algorithm managed to plan the production with an optimal cost of 38481.54 dollars in case 1, which obtained a more optimal value than all the compared algorithms. This reduction in cost is considered one of the triumphs of the optimization problems. The results showcased and juxtaposed in the software simulation verify the effective performance of the suggested approach in comparison to prior research.