نشریه تحقیقات نوین در سیستم های قدرت هوشمند
سال یازدهم شماره 3 (پیاپی 31، پاییز 1401)

The expansion of big cities, the ever-increasing demand for electricity consumption, the use of renewable energy sources, the creation of an electricity market, the high cost of creating new electrical networks and many other issues have caused the use of distributed generation in the power system to increase; Therefore, with the increase in the share of distributed generation in the supply of electrical energy, planning the use of these units is considered one of the important issues in planning the development of production and distribution networks. Wind and solar power plants are among the most important renewable sources that are used to produce electricity today, but these sources are somewhat unpredictable and their injected power to the grid fluctuates. In these systems, energy storage systems are usually used to compensate in case of power loss, or in case of power increase, to store energy in itself to inject it into the power grid when needed. The simultaneous use of several distributed generation sources of production should be such that the cost of production and the amount of losses are minimal. The lifespan of the batteries used in these cases is completely dependent on the number of charges and discharges and the frequency of the current passing through them. So, the life of the used battery can also be one of the influential parameters in how to plan this system for production. In this research, a network with three wind turbine units, three solar power generation units and three battery units is considered. This system is programmed using the optimization method of gravity search based on fuzzy logic in such a way that the cost of production and the amount of losses are minimized and the life of the battery is also increased.

In this paper, a new scheme for sensorless speed control of multi-phase induction machine under unbalanced supply conditions is proposed. There are many methods that use speed and flux estimators for sensorless control of induction machines, but the proposed scheme is based on current estimation without flux and speed estimation, in which the stator controlled voltages are applied to the machine so that the difference between the estimated stator currents and the real currents of the machine are forced to decay to zero. The simulation results in MATLAB/Simulink show that the speed of the induction machine in the start-up and speed reversal test follows the reference speed well. Also, in the load rejection test, by applying a mechanical load on the machine and then removing it, the proposed control method has the ability to control the speed of the machine well, and the performance of the machine will be stable under these conditions. Finally, a sensitivity analysis to the changes in the machine parameters shows that the proposed method has a relatively acceptable performance.

Providing the required resources to meet the energy demand of industry and minimizing the effects of these resources are the major current challenges of the electricity industry. One of the strategic solutions to this challenge is reconstruction of the smart distribution network, while not only increases the efficiency, but also reduces the costs. The advent of large power plants led to obsolescence of the small generators to generate electricity. However, the development of small-scale power generation technologies and the theory of reconstruction in the electricity industry, along with the environmental problems have led to the re-use of these generators in the electricity industry. By increasing the costs of transmitting and distributing, it is possible for DG to provide electricity for consumers with more affordable price. In these systems, the generated power by DG sources is controlled which can improve the voltage profile and reduce network losses with proper control of distribution network switches. These issues are mainly analyzed in the form of an optimization problem to improve the desired goals. In this paper, the problem of reconstruction in distribution networks is performed by determining the size of distributed generation to minimize the power losses and improve the network voltage profile. The desired optimization problem is solved by using the water cycle optimization algorithm. Reconstruction studies have been performed under the 33-bus and 69-bus systems. The simulations of this paper have been performed using MATLAB software.

With the advancement of energy issues and the increase of disputes over energy, various methods have been proposed to sanitize and prevent the shortage of energy resources. The best solution to the crisis is to save energy and its resources using renewable energy or sustainable transportation, each with its own advantages and disadvantages. Fuel cells are the most up-to-date example of sustainable transport for energy systems, and the fluids involved in this conversion are hydrogen and oxygen. Fuel cells have been studied in five main types with electrolytes. In this paper, a solid oxide fuel cell is modeled at a very high temperature so that it can achieve the maximum average power in this type of cell. Control in the fuel cell is very important. From the change of the initial polarization voltage, an attempt is made to control the performance of the cell, or in other words, to control the fuel cell. The range of changes in this diagram depends on the dimensions, geometry, voltages and energy of the cell. It is observed that if the current density reaches approximately 1700 amps per square meter, the average cell power reaches its maximum value, which is the main purpose of this simulation. The results also show that the higher the average current density in the cell, the lower the cell voltage, but with increasing initial voltage, the average current density will increase.

This article, proposed a method to coordinated utilization of gas-electricity integrated distribution system, including CCHP systems and renewable energy sources, considering AC load flow analysis in an electric grid and the calculation of gas consumption in a gas grid. In this research as you will see, an effective method proposed to prevent transmitting of power generation swings of renewable sources over trans-regional power line and maximum utilization of renewable sources. The proposed model tested on a modified distribution power grid IEEE 33 and 24-node-gas grid. Results show that total expense of adjustment in Conventional design will rise dramatically by increasing of unit. While in the presented design, adjustment expense will remain stable and increase slightly.

Nowadays, the use of renewable energy has become very important. Considering the changes in radiation intensity and the continuous switching of the inverter, the control algorithm of the inverter plays an important role. In the DC part, adjusting the voltage of the DC link is very important, and stabilizing the voltage at this point will have a significant impact on the performance of the entire system. In the existing methods in order to regulate the voltage, a proportional integral controller (PI) is used and the coefficients of this controller are usually fixed and its performance decreases when the working conditions change, so using structures with an approach Fuzzy is noticeable. The use of the fuzzy PI controller improves the performance of the controller, increases the speed of realizing the maximum power tracking algorithm, reduce the fluctuations of the DC link voltage and the output power of the photovoltaic system inverter. In this article, a new structure based on the fuzzy PI controller is presented in order to improve the performance of the inverter control algorithm, so that the DC link voltage becomes equal to the reference value for 2 seconds faster than the normal PI method and the grid voltage range for 1/5 seconds faster. And the active power of the grid will reach a steady state 2 seconds faster and the fluctuation of these variables will be significantly reduced.