فصلنامه روشهای هوشمند در صنعت برق
پیاپی 39 (پاییز 1398)

In recent years, the limitations of fossil fuel resources and the environmental issues, lead to a broad research in the field of renewable energies. Among renewable energy resources, solar cells, fuel cells, and wind turbines are more dominant. Therefore, the existence of a high step-up DC-DC convertor is necessary. In this paper, we focus on DC-DC converter with high voltage gain and output power of 200 watts. The proposed converter can convert the output voltage of one or more solar cells with low voltage to higher DC voltage and suitable for the input of a DC-AC converter. In this paper, the boost converter is combined with the coupled inductors and the capacitor-diode technique. This design aims to reduce the switching loss and conductive loss to improve the performance of the converter. The performance of proposed converter evaluated by simulation results and a prototype of the proposed converter with 200 W and 50 kHz. The results from simulation and the prototype depict the performance and accuracy of the proposed converter

Numerous methods have been introduced for digital images watermarking as well as rubosting them. In this method, with using Graph-based transform and extracts the best graph structure with genetic algorithm so that watermarking can be performed with maximum robustness. One of the common methods in watermarking robustness is the use of discrete cosine transform (DCT). In this study, we have shown that the proposed method is much more powerful than DCT. The proposed method is tested on five different color images such as Lena, Barbara, Boat, Baboon, Peppers. Watermark image (logo) is a random binary image with size 16 x 16 and 8 x 8 pixels. This simulation results show that the proposed method is more robust to similar methods such as discrete cosine transforms. Proposing Watermarking has been evaluated using Bit Error Rate (BER), Structural Similarity Index Measuring (SSIM) and Peak signal-to-noise ratio (PSNR) criteria and different strength Gaussian noise attacks, JPEG compression, median filter, bluring, rescaling, rotate and cropping attacks

 In this paper presented discussed to design a low noise amplifier (LNA) with inductor at source in TSMC 0.18um CMOS technology to 2.4 GHz. Cascode structure cause reduces the power consumption of the circuit[1]; the advantage of using cascade structure, increase the output impedance of the circuit impedance increases, increasing the circuit to follow. The circuit presented in this article a low noise amplifier cascoded with inductor in the source along with impedance matching network added in the input and output; and led to 1.6db noise figure and power consumption of 2.1mw achieved, respectively. Add matching networks to a greater degree of freedom in circuit for improved noise figure and power consumption and chip internal area is also reduced. Add the rest of the circuit in addition to reducing power and noise figure considerations in mind we have been able in the desired frequency and reflection coefficient in the input circuit respectively 20db and -12db achieved.

One of the issues which has attracted a lot of attention in the power grid in recent years is the emergence of microgrids. An optimized microgrid design includes choosing the best combination of the available options (distributed generation units, energy storage systems, and load response programs) to supply the microgrid so that the total costs of the microgrid development plan is minimized. In this article, a comprehensive modeling has been conducted for the problem of optimal design of residential microgrids considering the renewable distributed generation units, energy storage systems and controllable loads. This model takes into account the intrinsic stochastic behavior of renewable energy and the uncertainty involving electric load prediction, and thus proper stochastic models for them has been chosen. In order to find the optimal solution, the problem of microgrid design is modeled as an optimization problem with the goal of minimizing the total costs of the microgrid development plan and the optimal response is determined via ant colony optimization algorithm.

Due to explosive growth of users, increasing energy demand and also the need to improve efficiency and maintain the stability of the electricity grid, smart grid is the only option available to electrical industry engineers. In fact, the smart grid is a physical-cyber system that provides coherent and integrated communication, processing and control functions. The smart grid provides control and management of millions of devices in the electricity industry in a reliable, scalable, cost-effective, real time and two-sided manner. Given the increasing growth of cyber threats in the last decade, the need to protect the electricity industry and its critical systems seems essential. The slightest disruption to the power industry's systems results in disruption to other industries, reduced productivity, and discontent. Hence we proposed an efficient cloud based architecture to improve smart grid performance. Proposed architecture provides data security and privacy against different types of cyber-attacks such as replay attack, modification attack and so on.

In this paper, the control problem is investigated for Jerk chaotic systems against unknown parameters, actuator faults and input saturation. The considered actuator fault covers both of the stuck faults and loss of effectiveness faults in actuators. The values, times and patterns of the considered faults are completely unknown. That is, during the system operation it is unknown when, by how much and which actuators fail. A robust adaptive controller is presented based on the backstepping design method to achieve complete synchronization of the identical Jerk chaotic systems. By introducing the new Lyapunov functions, it is proved that all the closed loop signals are bounded and the tracking error converges to a small neighborhood of the origin. The proposed adaptive method compensates the actuator faults without any need for explicit fault detection. Simulation results represent that the designed controller can synchronize the identical chaotic systems in the presence of actuator fault, input saturation and unknown parameters.