Arc-to-glow transition approach for practical use in DC low-power, low-voltage electric grids

© 2018 IEEE. This paper presents and discusses results of analysis from investigations of arc-to-glow transformation phenomenon at contact opening, under dc low-energy (≤ 10 J) and low-voltage (≤250 V) inductive loads. Dependence of the duration of arcing and glowing on current magnitude, voltage magnitude, properties of the contact material, gas quenching medium velocity and its pressure, as well as contact opening velocity and contact gap are investigated. The transition phenomenon of arc-to-glow is analyzed by means of fast photography and emission spectroscopy. Also discussed is the theoretical evaluation of conditions of arc instability. From the results, possible procedures are formulated to control the arc-to-glow transformation for practical use in dc low-voltage and low-power electrical grids

PID controller design for a novel multi-input multi-output boost converter hub

This paper reports on the design, control, and modeling of a novel multi-input multi-output boost converter topology. The converter hub can integrate renewable energy sources such as wind turbines, photovoltaic arrays, and fuel cells for the provision of different output voltage levels. The advantage of energy sources integration is that the required output voltage levels could be made up from a range of sources. The designed converter has the advantages of a simple configuration, fewer components, high conversion ratio, and high efficiency. The regulated output voltage levels are achieved through classical PID controllers which utilize the concept of closed-loop voltage-mode control. Design of the converter control system requires comprehensive knowledge of the converter structure, its operation principle and the small-signal model for continuous-conduction operation mode. The validity of the converter’s control performance is demonstrated through software simulation

New studies on network frequency responses considering dynamic loads

The dynamic model construction of transmission network components that include generator buses, load buses and power branches, within MATLAB-Simulink environment is presented. The degree of frequency deviation of buses when the power of motor loads and static loads vary, is studied. Furthermore, the influence of motor loads with different inertia constants are considered in the control technique of load frequency using a PID controller. The results show that the frequency oscillation of the dynamic load is greater than the frequency oscillation of static load. Also the speed of frequency control of the dynamic load is greater than the speed of the frequency control of the static load and the inertia constants of the dynamic load has significant influence on the frequency control characteristics

Effects of high frequency modeling & grounding system parameters on transient recovery voltage across vacuum circuit breakers for capacitor switching in wind power plants

© 2018 Elsevier Ltd This paper investigates the transient recovery voltages across vacuum circuit breakers used for the switching shunt capacitor bank in wind power plants, which are connected to the power system. Consideration has been given to high frequency models of all power system components, such as, the transformer, wind power plant generator, cable, surge arrester, vacuum circuit breaker and grounding system. The initial phase of study reproduced the results of previous work. In the second phase, the influence of different parameters, such as, the grounding system network, current injection point location to the grounding system, soil resistivity, grounding system length segment and soil ionization phenomena in the grounding system on transient recovery voltage, have been investigated via EMTP-RV. The results show that consideration of the high frequency behavior of the grounding system in wind power plants for prediction of transient recovery voltages is very important

Post-modernism in Iraqi Planning Experience

Iraq faces several problems as a result of its engagement in several wars, which brought great consequences. Wars continued for nearly a century. Iraq was in a position of continuously watching and defending for its national identity and existence. This was reflected negatively on its economy, society, and its environment and progress. According to these facts, it is difficult for this country to have the opportunity to be involved in an intellectual and philosophical dialogs such as (post modernism issue) for the sake of imitating developed, safe, and economically settled countries. This paper presents the existing situation of Iraq and type of problems facing it, and the consequences facing its reality. Also, giving solutions for its problems and proposing to postpone the intellectual dialogs for another stage

A fast fault classification technique for power systems

This paper proposes a fast fault classification technique using three phase current signals for power systems. Digital Fourier Transform, the ‘Least Square’ method or the Kalman Filtering technique are used to extract fundamental frequency components of three phase fault currents. Fast fault classification can be achieved using the fault probability of three phases. Results from simulation work on EMTP have validated the proposed fault classification technique. The response time of the fault classification technique using the ‘Least Squares’ method is 1.875ms (3 samples) for single-phase-to-earth fault, two-phase-to-earth fault, two-phase-fault and three-phase fault

Circuit modelling by difference equation: Pedagogical advantages and perspectives

Circuit theory is a cornerstone course in electrical engineering and control majors in ordinary universities and colleges throughout the world. This course covers fundamental principles and analysis methods of basic circuits commonly employed in the forthcoming courses. In most electrical programs after the introduction of basic elements of Ohm's and Kirchhoff's current and voltage laws, the dynamic response of the circuits containing capacitors and inductors will be studied. Customarily to solve these circuits, advanced mathematical approaches such as differential equations are used. Under such circumstances, the students are faced with two challenges, solving the differential equations, and understanding the dynamic response of circuits. In order to improve students' understanding, an analysis tool with less mathematical prerequisites should be used for the solutions before embarking on the use of conventional differential equation techniques such as Laplace transform. Hence, we propose a novel approach for these circuit analyses through the application of a discretized version of differential equations which is used in discrete control systems. Although this approach has a well-established background, its exploration uses in the circuit theory course as yet has not been reported. The novelty of the proposed approach not only lies in its intuitive simplicity but also in its contribution to the understanding and visualization of students in the real-time response of linear and non-linear circuits to any desirable input without any mathematical burden. The analysis can be performed by hand or this is also helpful for those who prefer modern education aided by computers. This, in turn, may attract more students to the program. In this paper, the effectiveness of the proposed approach is demonstrated through a set of illustrative examples

Cross‐entropy method for distribution power systems reconfiguration

Cross-entropy (CE) is a powerful simulation method for the solution of continuous and combinatory optimization problems. The work presented here utilizes the CE method for the optimal topology of distribution power systems (DPSs). The optimal network switches are determined for the reduction of active power loss. The adapted CE method is tested on three case studies, namely, the 33-node, 83-node, and 880-node DPSs. The results are compared with other reconfigura-tion algorithms to demonstrate the superiority of the proposed algorithm. The impact of the distributed generation is also investigated. The effective integration of the photovoltaic panels at midday, when their production is highest and meets the peak demand, is showed. Finally, the real-time reconfiguration strategy based on the switching effort reduction is proposed and enhanced via an adequate selection of the initial switch states