نشریه فناوری های نوین مهندسی برق در سیستم انرژی سبز
پیاپی 2 (تابستان 1401)

Today, due to increasing trend in fossil fuel price and environmental concerns, use of electric vehicles (EVs), which are mainly capable of connecting to the distribution network, has grown. The electronic power converter that connects the EV battery to the grid, it makes it possible to use the EV when connected to the distribution system (connected to charging stations or connected at home and even connected when parked in parking lots) to mitigate network harmonics. Due to distributed nature of EVs in power grid, to implement the aim mentioned above, we must execute distributed power line conditioners (DPLC). In this paper, with investigate active filters distributed in the network and present a grid connected EV model for harmonic studies, to their DPLC has been addressed. For simulation, IEEE 13 Node Test feeder is used, that The results confirms the applicability of the proposed model for grid harmonics filtering.

This paper proposes an integral sliding mode direct power control (ISM-DPC) strategy for brushless doubly fed induction generators. Two widely applied control strategies are available for this type of generators: hysteresis-based direct power control and vector control. Direct power control suffers from high power ripples and current distortions produced by variable switching frequency. Moreover, the tuning issues of PI controller, which are highly reliant on machine parameters and operating conditions, and necessity of a phase-locked-loop for frame alignment are accounted as limitation of these methods. The proposed integral sliding mode strategy directly controls active and reactive power to provide fast dynamic response and zero steady-state error. This method is developed in the control winding reference frame to avoid the application of PLL. A large-scale brushless doubly fed induction generator (BDFIG) is simulated to validate the effectiveness and robustness of the proposed ISM-DPC method in comparison with widely applied methods, vector control and direct power control.

This paper investigates the closed loop stability of the SEPIC converter using an optimal PID controller; In this model, the parameters are adjusted using the Gray Wolf Multi-Objective (MOGWO) algorithm. The Gray Wolf Multi-Objective Algorithm is a random evolution-inspired random algorithm that has been widely used in recent years as an optimization technique in power electronics. The state mode average method has been used to model and achieve the transducer-based system transfer function. Therefore, the MOGWO-based PID controller has been studied and implemented in the system to enable the converter stability to be evaluated and compared with conventional PID controllers. To evaluate the stability of the system, various performance parameters such as overtaking percentage, peak time, settling time and peak size have been considered. The impact response of the closed-loop system is obtained by simulation in MATLAB. The performance of the model is evaluated to perform a general comparative analysis of the system.

The rapid growth of grid-connected embedded distributed generations (DGs) is changing the operational characteristics of distribution networks (DNs). In order to implement DNs with DGs, some challenges should be faced, especially concerning protection issues, that may make conventional protection schemes ineffective. MAS techniques can enable the power grid to becomes smarter, reliable, selfhealing, and robust. Its decentralized nature and operational robustness make the MAS application a leading technology. Despite the fast, reliable and multi-purpose operation of MAS-based protection schemes, the inherent delay or failure of communication system must not affect the vital role of fault clearing, i.e., the ever-increasing DGs in DNs as well as network size increase has resulted in a heavy communication burden yielding to delay or even failure in communication. In this paper, an Intelligent protection algorithm is presented that protect the grid, when the connection between agents is lost, by using point-to-point communication between relay agents in the first layer of the MAS. Reduction of the agents used and no need to connect to the higher layers of the MAS  are the benefits of this method. For simulation, 16 bus Test DN is used, that The results confirm the applicability of the proposed model for grid protection coordination.

A high step-up two-inputs DC-DC converter is presented in this paper. The soft switching condition is provided for switch in turn on instant, so the converter efficiency is high. Due to the fact that only the capacitor is used to increase the voltage gain and there are no coupled inductors in the converter, the input current of the converter is continuous. The technique used to increase gain can be used with more stages to achieve higher voltage gain. The converter can also be used as a single input intertwined instead of two inputs, which in this case the input current ripple is reduced. The voltage stress on the switches is lower than the output voltage, so lower voltage switches can be used, which reduces the converter cost. The proposed converter is completely analyzed and in order to prove the theoretical results, a simulation is performed on the converter at 500 watts. The results of the simulation at full load show an efficiency of about 95.5%.

With the rapid progress of semiconductors in the level of voltage and power of the power system as well as the progress of control systems, compensators with high flexibility and performance range have been designed and built to increase the flexibility of energy transmission systems. to be These compensators installed in power systems are called flexible ac transmission systems (FACTS). One of the most important advantages of FACTS devices in the transmission system is to increase the transient stability margin of the power system by controlling the active and reactive power of the line during the occurrence of a fault in the system. In this article, the effect of one FACTS device with parallel connection, i.e. static compensator, on transient stability is investigated. The studied system is a two-machine power system including a hydropower plant and a local power plant. The simulation results show the effect of the compensator on the damping of electric power angle fluctuations. Also, the simulation results show the lack of influence of the compensator on the transmission active power in the transmission line. The simulation results have been obtained using Simulink MATLAB software.