نشریه فناوری های نوین مهندسی برق در سیستم انرژی سبز
سال دوم شماره 3 (پیاپی 7، پاییز 1402)

In this paper, a non-isolated current-fed high step-up soft-switching converter, is presented. In proposed converter are used of 2-stge switched capacitor and a soft switching active cell. Compared to its high step-up counterpart, the proposed converter has a higher voltage gain. In this converter, an active clamp circuit is used to absorb the energy of leakage inductor, therefore, the ZVS for switches. Also, voltage stresses on the switches are low. In this paper, the operational principle and characteristics of proposed converter are presented, and in order to verify the proposed converter, a 20-400V, 200W prototype converter is simulated and implemented and experimental results are provided.

Electro-hydraulic servo systems are one of the most important control systems used in many fields such as industrial automation, numerical control machines, the oil and gas industry. Due to the non-linear behavior of hydraulic system components and the presence of various uncertainties in their operation, the modeling and control of these systems face problems. In this paper, a fuzzy adaptive controller based on sliding mode control is proposed to control the position of an electrohydraulic servo system and overcome the uncertainties. The proposed robust controller results in minimal dependence on the system model. The system's stability in the presence of uncertainties has been proved by applying the Lyapunov theory and considering the time-varying nature of the uncertainties. Besides, to approximate the maximum band and the range of uncertainties, an adaptation law has been proposed for its estimation. The simulation results show the reasonable and stable performance of the proposed adaptive fuzzy controller compared to other control methods.

An effective high-step-up DC-DC converter is an important section of renewable energy systems. Cascaded boost converters provide more voltage gain than single boost converters, but they are still unsuitable for high step-up voltage conversion due to gain and hard switching conditions. To improve the voltage, gain of the cascaded boost converter, a coupled inductor can be used but the leakage inductance causes a voltage. To overcome these problems, a high step-up converter is proposed in which a cascaded structure, coupled inductor, and a lossless passive snubber are utilized together. The proposed converter has zero current and zero voltage switching conditions at turn-on and off instants. First, the proposed converter is theoretically analyzed, and then its design and simulation in OrCAD software are presented.  Furthermore, the experimental results of the prototype verify soft switching conditions and high step-up gain.

By increasing the penetration level of renewable distributed generations and increasing the size of the distribution networks, the more number of agent-based protection systems with its communication infrastruture will be used. Such systems play a vital role in the protection system to detect the faults and maintain the protection coordination. Despite the fast and reliable nature of multi-agent systems, there is a possibility of poor performance especially in protection coordination schemes with heavy communication load. For this purpose, this paper presents an intelligent self-healing method under fault conditions, which provides the protection coordination in a single control level without dependence on a higher communication level. The decentralized performance of the proposed scheme is expressed by using intelligent electronic devices and distributed communication. Accordingly, the coordination is done using the high-speed point-to-point communication capability of the IEC-61850 GOOSE protocol. Also, to avoid power outages due to the protection system malfunction, an algorithm independent of DG peneration and based on GOOSE message service mechanism is proposed, which does not need a central processor. Finally, the performance of the proposed algorithm is evaluated under different scenarios in a practical distribution network using ETAP software environment.

Today, one of the most important challenges of power network operators and designers is to find a suitable solution to deal with the increasing presence of distributed generations in distribution networks for abnormal operating conditions such as fault conditions. The existence of environmental and economic advantages of distributed generations has led to the expansion of the use of distributed resources, especially renewable resources, and as a result, changes in the topology of the power system and becoming an active network at the level of the distributed network. Despite the existence of many advantages of distributed resources, this issue has caused disruption in the performance of the protection equipment of the distribution network to the point where the conventional methods of modifying the protection settings are not responsive. In this article, there is a comprehensive review on new solutions in the field of modifying and restoring the protection system of distribution networks in the presence of distributed generations. For this purpose, the performance of the protection system has been evaluated. Also, through the general classification of studies conducted in this field, the weak points or strengths of each of the study groups as well as the proposed strategies have been determined.

One of the main components in the security of cryptography systems is random numbers. Random numbers are often used in the generation of secure keys, digital signatures, and other cryptographic systems. Random numbers generated by an algorithm are called pseudo-random numbers. Although pseudo-random numbers have good statistical properties, they have the problem of periodicity. For this reason, to generate random numbers, the true random number generator method is used, which uses a physical entropy source to generate random numbers. In the real random number generator method, due to the instability of electric circuits, a post-processing step is needed so that the generated numbers have acceptable statistical characteristics. In this paper, an overview of the common post-processing methods of random number generators has been done, so that some of the introduced methods are also used in the generation of quantum random numbers. An important point is the role of renewable energies in the design and construction of devices with limited computing power. For this purpose, in the final part of this article, a fast and optimal post-processing method is introduced in terms of hardware implementation, which can be used in mobile phones, smart cards and devices that have limited computing power.