ISSN 1805-3386

April 6, 2020


2019 No.4

DC Network Model Based on VSC-HVDC System

Aleisawee Alsseid, Abdulrahman Emhemed, Alhade Algitta.

The recent developments in high power rated Voltage Source Converters (VSCs) and the control strategies have resulted in their successful application in HVDC transmission systems, which have become an attractive option for renewable energy applications or for distribution power in large metropolitan areas. A 153th order multiple-input multiple-output (MIMO) small-signal model of DC network model based on VSC-HVDC system and controls is developed in state-space form within MATLAB. The optimum values of the controller gains are selected by analyzing the root locus of the analytical model. The developed small-signal detailed models are linearized and implemented in MATLAB. The validity and accuracy of the proposed models are verified against nonlinear PSCAD/ EMTDC and a summary of the model structure and controls is presented in detailed. Confirmation of the effectiveness of optimization gains is done by simulating the modelled system in MATLAB and PSCAD software. There simulation results performed with very good matching is confirmed in the time domain. It is the most detailed model currently available.


Keywords: DC network model, voltage source converter, high voltage direct current, DC voltage control, modelling multi terminal VSC HVDC.


Full paper (.pdf) - Download here


Protection against the Effects of the Asynchronous Operation of Synchronous Motors Based on the Principle of Comparison of the Machine Power Factor

Gric, P.

This paper deals with the possibility of using the principle of comparison of the operational power factor for evaluation of the asynchronous operation of synchronous motors. This way of definition of the asynchronous operation is possible to use for motors protection and other protective systems of drives with synchronous motors.


Keywords: synchronous motors, asynchronous operation, power factor evaluation.


Full paper (.pdf) - Download here


The Cause of Mechanical Vibration of Palasher Synchronous Motors and its Removal

Pavelka, J., Šimek, J., Kobrle, P., Kokeš, P.

The paper describes the procedure and the result of the analysis of mechanical vibrations of mining machines at the Palasher mine in the Russian Federation. The cause of these vibrations was the change in the magnitude of the magnetic flux in the air gap. The simulations showed the possibility of eliminating these changes in magnetic flux by injecting suitable voltages into the stator windings. The implementation of this injection is further described by torque variable component feed-direct compensation. Finally, oscillography records are presented before and after injection.


Keywords: mining machine, synchronous machine, indirect frequency converter, Maxwell’s force, resonant frequency, feedforward compensation, voltage injection.


Full paper (.pdf) - Download here