نشریه تحقیقات نوین در سیستم های قدرت هوشمند
سال دوازدهم شماره 1 (پیاپی 33، بهار 1402)

Helical magnetic flux compression generators (HFCG) and Two Stage-Helical flux compression generator (TS-HFCG) have been widely used to produce very high current pulses for many applications in recent decades. In order to accurate analysis and optimized design of these generators, it is necessary to calculate their electrical parameters. Among these electrical parameters, calculating the self and mutual inductances is important because it reduces the design and construction costs. In this paper, the calculation of self-inductance and mutual inductance profiles of TS-HFCGs is carried out using a three dimensional numerical method in the presence of an armature and its dynamic. For this purpose, the Maxwell equations governing the system are expressed in different parts, and then, using the utility software, the equations are solved and the inductances are obtained. In order to validate the results, a computer program is written in MATLAB based on the filamentary method and the results are compared.

The proposed structure of this article is a hybrid wind-solar-storage system with fault tolerance that reduces output power fluctuations and voltage drop in the system caused by faults. In the proposed topology, the solar system is connected to the DFIG through a DC-DC converter, thus eliminating the need for a special inverter for the solar system and reducing the cost. The power management in this system is done using the converters of the rotor section and the DC-DC controller related to the DC link using the phased method, which is why there is no need to use a compensator in the system. The better the control system works, the better and sooner the fault detection and compensation will be done, and this will prevent the system from being damaged and unstable, and will not cause serious damage to the system. In this thesis, the simulation results for two scenarios were investigated. In both scenarios, the active power decreases during 0.3 seconds when a sudden voltage drop occurs, but the reactive power increases due to the compensation of the created error. With the occurrence of an error and a sudden voltage drop in the system, the wind turbine has not reached an unstable state and a sudden increase in torque has not occurred, and the control system has worked well. Therefore, in this research, the proposed system was able to perform fault detection and voltage drop compensation through DC link voltage stabilization and reactive power injection in order to improve the voltage drop. It should be noted that all simulations were done in MATLAB/Simulink software.

Electricity transmission lines in the unstable state have problems such as the increased voltage at the end of the line and loss of stability, and in pregnancy, problems such as voltage drop and loss of transmissible capacity, and in some cases of voltage instability, include transient power fluctuations and instability due to disturbances. These problems are exacerbated by the increase in the length of transmission lines. To solve these problems, the active and reactive voltages and capacities must be controlled momently to reduce line losses and increase power transmission capacity as well as improve reliability and maintain voltage stability the use of FACTS equipment is now expand worldwide and can be studied and proposed for the prospects of Iran's national grid. In this article, a more complete model based on weighted and ranked of different possible events simultaneously and optimally locating two examples of these devices including Thyristor Controlled Series Compensator (TCSC) and Static Reactive Power Compensator (SVC) to improve Available Transfer Capability (ATC) is proposed in 14-bus and 24-bus power networks by the IWO (Invasive Weed Optimization) method and then its results will be compared and evaluated with other optimization methods.

Today, the role of electric energy in creating social welfare and industrial development of human societies is not hidden from anyone. In recent years, comprehensive and complete laws have been compiled and implemented for the production and supply of this energy in the market. What shows up more than ever is the concern of engineers in this field for the production, transmission and uninterrupted supply of electrical energy. The use of efficient equipment with high reliability has led engineers to use gas insulated posts in transmission and distribution networks. The use of gas insulation, while reducing the dimensions, has caused a reduction in transportation costs and installation and commissioning time of this equipment. Although gas insulation equipment requires minimal repairs due to special manufacturing technology and insulation, but the reliability and proper functioning decreases as the life of this equipment increases. Often over time, partial drainage is a defect that occurs in this equipment. This event leads to insulation failure finally, which is an important quantity in assessing insulation conditions. The most common causes of partial discharge in gas substations are three factors: conductor electrode protrusion, Existence of void in insulation and free particles suspended in gas pressurized enclosure. In this paper, studies related to the factors affecting the insulation failure of GIS substations and its timely detection methods, based on the benefit of existing articles and research.

This deals with the separation of the insulation model from the coil ladder network model in order to obtain the insulation losses of the coil in fast transients. Ladder network model or RLC Ladder Network (RLC) is introduced as a coil fast transient model for studying fast transient phenomena at high frequencies. In this study, the coil insulation model is separated from the RLC model and all circuit relationships related to this model are rewritten. The electrical parameters of the insulation are calculated by the substitution method in the resonant circuit. The single-phase windings of the 6KV induction machine are modeled with the help of the proposed model and by simulation in the Ansys Maxwell software; the voltage distribution waveform, the insulation loss coefficient, and the insulation loss at different points of the wire are shown. In the following, the voltage distribution waveform of the nodes, the current passing through the coils, the voltage on the coils and the power losses in the coils are compared by two classical RLC models and the proposed model. In this study, according to the separation of insulation losses from winding losses in fast transients and at high frequencies, the proposed model can be used as a suitable tool to achieve more accurate responses of fast transient phenomena.

In this paper, a DC/DC converter with high gain voltage for application in photovoltaic (PV) system is suggested. The proposed structure has the advantages of the simplicity of the structure, the use of only one controllable semiconductor switch, direct connection between the input source and the load, suitable voltage gain and optimal performance in tracking the maximum power in photovoltaic systems. One of the most important features of the proposed structure is the series placement of the output capacitor and the main source. In other words, the voltage source has a short path to feed the load compared to conventional step-up converters. Theoretical analyzes are presented to investigate the performance and design of the power circuit in the continuous conduction state. To confirm the optimal performance in the photovoltaic system, the simulation results have been evaluated in MATLAB/SIMULINK software. Also, a 100 W laboratory sample of the proposed converter was made.