نشریه عصر برق
پیاپی 9 (تابستان 1397)

The increasing consumption of electrical energy along with economic and environmental issues arising from the development of power systems cause to operation of power networks with full capacity and close to stability margin. This would reduce the safety margin against various instabilities and possible collapse of power system in the network. The protection of power systems to maintain stability in the face of various events is very important. One of the instability of power systems, which can lead to network collapses, the sudden disruption of the balance between production and consumption that is leads to collapse of the grid frequency. Among, load shedding can be an effective way to prevent the frequency instability. In this paper is proposed a practical approach based on the frequency drop to determine total load shedding (TLS). The performance of proposed method is implemented on Iran South East network using PSS/E and the obtained data are analyzed by MATLAB software. The simulation results show that the proposed scheme could be a very effective way to prevent the network collapse in case of simple, moderate and severe disturbances.

An innovation technique is presented to transform the maneuvering target tracking problems from Polar coordinates to Cartesian coordinates, therefore a standard linearKalman filter can be easily applied to them. Extended Kalman filter and unscented Kalman filter are two conventional methodologies for nonlinear estimation. In this paper a new relation between measurement noise covariance in sensor coordinates and the measurement noise covariance in Cartesian coordinates for Kalmanfilter implementation is proposed.In addition the proposed technique is based on the well-known equivalent noise approaches. The simplicity of implementation and target tracking improvement with computation effort reduction, are three important advantages of the new approach comparing with extended Kalman filter and unscented Kalman filter. Simulation results show this modified filter can predict target parameters more effectively and accurately than EKF and UKF

Nanorabot is a nano-controlled robotic system.This tiny robot has features such as the ability to use in small spaces with high flexibility, high responsiveness and adaptability in a variety of situations. Nanorobotic is so fast-paced that it will soon change human’s life; these changes are based on the design of biological nanorobos that are located in the human body and play the role of protector or therapist.This tiny intelligent machines can produce multiple copies of themselves and replace worn and damaged their tissues.Today, the technology of designing and manufacturing nano-robots has attracted many scientists and industries due to the wide range of applications in various fields of science such as medicine, biotechnology, mechanics, electronics, physical systems and communication systems.Nowadays, the design and manufacturing of biological nanorobots in the field of medicine, health and pharmacy is more than other areas and has been making a lot of progress over the past few years.However, the construction of these tiny robots requires more research because of the complexity of the human body, which is able to move through the arteries of the body and to investigate and identify diseases.In this article, we study the design and characterization of biological nanorobots that are widely used to identify and treat many diseases

Congestion control is an important issue in telecommunication networks, and with the growing need of bandwidth, load, size and network connections, its importance is increasing. This issue requires the design of networks with appropriate congestion control algorithms, especially for wireless sensor networks. This paper outlines the congestion control methods available in wireless sensor networks in terms of congestion notification, congestion detection, and congestion avoidance.

This paper presents the applications of observersin robot-assisted medical procedures, in whichrobotic manipulators act in collaboration with surgeonsor therapists to improve the efficiency and accuracy ofthe interventions. Observers can be considered as replacementsfor sensors to provide the surgeon and/or therobots with information about the tissue, surgical tools,and their interaction. This paper provides an overviewof the observation methods for estimating the tool pose,tissue motion, and the interaction forces. Having a goodmodel for the system and guaranteeing the safety andefficiency of the methods are the challenges involved inusing the observers in medical procedures. However, theapplication-driven nature of the medical robotics providesa thriving field of study for using the observers

Solar systems that have been built so far in Iran usually do not meet the expected efficiency.Lack of proper efficiency of solar power plants is mainly due to poor design and non-use of softwares available in this field. In this research, a 5KW grid-connected photovoltaic system located in Tehran Power Distribution Company (TehranPars Electricity Distribution Company) has been investigated technically and economically and has been influenced by factors affecting the amount of power plant production and practical solutions for increasing the plant's efficiency.To simulation, design and technical analysis of PV power plant PVsyst software is used.

In this paper, a new optimization method is proposed that is inspired by bounce motion algorithm based on sound reflection to find the angles of fire in multi-level inverters of the voltage source to reduce the total harmonic distortion (THD). In the proposed method, the angles must be calculated so that the amplitude of the required main frequency voltage is generated and at the same time the output of the THD is low. This method can be used for multi-level inverters with any number of levels. In this paper, the 7-level inverter and optimum switching angles will be calculated as the plane and finally the results will be presented

Environmental problems suffering from fossil fuels,trying to find alternative human energy supply and the presence of huge amount of energy in wastewater, considers sewage as an economicallyviableand environmentally-friendly optionsource of energy.Also, wastewater treatment in a localized manner consults reuse of water in the water cycle, but a recovery of wastewater and the return of water to the water cycle requires lots of energy.Using microbial fuel cells as a solution to this path is considerable andwastewater treatment, using these types of fuel cells, would make it possible to generate the energy required by the system.