Performance Analysis of UPQC Architecture at Different Load Conditions

The UPQC has the ability to improve the network quality at the installation site in electrical distribution networks or industrial electrical networks. The main objective of this thesis is to design a system to improve the network quality with a simplified architecture to support reactive power as well as to improve the active power available for load connections and to improve the efficiency of the system controls mentioned above. From this work, it was deduced that by developing and the inverter system with an control strategy in SVPWM, the device are proposed to improve the quality of the network can serve this goal with better results in the terms of performance and the efficiency. In this architecture can also be used in the hybrid systems, in making it more reliable. The designed system is also suitable for the delivery of different types of loads, such as non-linear load, symmetrical load, and asymmetrical load.

Assessment of load on the lumbar spine using two computerised packages and REBA method

Purpose: The aim of the research was a comparative analysis of the back lumbar load assessment using three methods: two with continuous input data and evaluation procedures based on mathematical relationships (ShiftBack, 3DSSPP) and one method with categorized input data and tabular load estimation procedures (REBA). Methods: For the analysis, work activities and the value of applied force were selected. Among the analyzed 24 work activities were those during which there was a symmetrical load, as well as those during which the applied force or the assumed position of the body caused a lack of load symmetry. Results: The results show that the REBA method differentiates 24 cases of unit load into six levels, while the other two methods provide 24 different values between cases. Cases differing in load even over 100%, when assessed according to the 3DSSPP or ShiftBack do not differ in the assessment of REBA. Differences in the assessment of the same tasks between the results obtained from 3DSSPP and ShiftBack that were above 15% concern only 7 cases. Conclusions: A comparative analysis of the assessment of the lumbar part of the back using three methods indicates strong correlations between the results of the assessment carried out using 3DSSPP and ShiftBack. Smaller relationships were demonstrated by comparing these two methods with the REBA method.

Simulation modeling balancing current in the traction network of a substation group

This article is devoted to assessing the transit of electricity from an external electrical power supply system through the traction network of a railway district that includes nine traction substations. Substation transformers has star-delta-11 connection. The paper presents a simulation model of the railway district implemented in the MATLAB/Simulink software package. Various options of loading the external power supply system are modeled including into account the symmetrical load of the external network and the single-phase load of traction substations. The values of the voltage difference on the traction windings of power transformers of adjacent substations that occurs at different loads, the balancing currents that this difference creates and real power losses in the inter-substation areas are calculated.

Membrane Solution for a Catenary Dome

A membrane solution for a catenary dome is presented. The theory solves for the meridian and hoop stresses, assuming a symmetrical load. The theory is extended to solve for domes with an oculus, or rather a circular hole at the apex of the dome. The proposed theory does not include boundary effects, but a verification of the theory indicates that the boundary effects are minimal, compared to other dome shapes. The theory is verified by comparing the equations with a finite element analysis, which indicates an almost perfect match. Only a slight deviation occurs near the boundary, substantiating the legitimacy of the solution.

Application of training and methodological complex Electrical Engineering

The paper presents the laboratory practicum on electrical engineering and physics worked out on the basis of the teaching guide on electrical engineering including 5 test benches. It includes 24 laboratory works with elements of independent research. The detailed and illustrated test benches of the training complex are the following: Electrical Engineering and Electronics, Electric Machines and Electric Drive, Electric Machine Assembly, Electric Energy, its Transmission and Quality, Principles of Electrical Safety. Some stands are connected to a software and hardware complex designed for measuring the studied values, reflection and processing of analog signals. The compactness and versatility of the training complex Electrical Engineering are noted; one can do 6–9 laboratory works on electrical engineering and physics at one stand. Mathematical calculations of the readings are recommended to perform in Mathcad computer algebra system. A manual based on the laboratory works, which contains general safety rules, guidelines for per-forming tasks and requirements for their processing, is now under consideration. The advantages of the elaborated laboratory workshop have been listed; the educational, developmental, pedagogical tasks for solving at the lesson have been analyzed; a laboratory work “Three-phase circuit connection in star scheme” is given as an example. The diagram of a star connection is presented; a vector diagram of linear and phase voltages relations in a star connection is built. The oscillo-grams of currents under symmetrical load are illustrated. It has been noted that the individual tasks have an exploratory nature, they develop cognitive, independent and creative skills of students. The proposed methodological guidelines are recommended for specialists and bachelors in such areas as “Ship and Power Plants”, “Shipbuilding”, “Heat and Power Engineering and Heat Engineering”, etc., and can be used by teachers of general engineering disciplines

Taihe Circuit, a Novel Circuit Topology for Conversion from Single-Phase to Three-Phase

This paper presents a brand-new splitting phase topology based on three-phase full-bridge inverter, which is named ‘Taihe Circuit’. This circuit topology resembles the traditional three-phase full-bridge inverter except for the direct connection of its two-phase output with the two terminals of the one-phase power source. Its operating principles are as follows: one-phase power source first charges the DC capacitor through three-phase full-bridge inverter in a small time period. After the voltage of the DC capacitor reaches stability, three-phase full-bridge inverter can output three-phase symmetrical AC voltage. The average power of the one-phase AC source equals to the power consumed by the three-phase symmetrical load, and the fluctuation of the power of the AC source corresponds to the charge and discharge of the capacitor on the DC side of the inverter. This circuit topology can achieve the conversion from one-phase AC source to three-phase symmetrical AC source when knowing three-phase load and can be used cooperatively with other circuits in some situations. In comparison to traditional scheme, a combination of one-phase rectification and three-phase inversion, the proposed brand-new topology requires less power electronic devices, as is more economically practical. As a final note, feasibility of the topology is verified through simulation.

Stability Analysis on Double-Layer Single Span Rigid Frame with Sway Based on FEM

The FEM model of a double-layer single span symmetrical rigid frame was established in this paper, by changing the linear stiffness ratio between beam and column, the rigid frames stability with sway under the symmetrical load was analyzed, and the buckling load of rigid frame with linear stiffness ratio between beam and column was obtained, then the calculation length of corresponding column could be obtained too. The results were compared with the theoretical analysis results of displacement method, provided reference for the buckling analysis on double-layer single span symmetrical rigid frame with finite element theory.