Jerzy Szczepanik

A matrix N×M multiphase converter is a simple structure incorporating N×M bi-directional switches, connecting N input phases to M output phases and able to convert input voltages into output voltages of any shape and frequency. However, commutation problems and complicated control algorithms keep it from being utilized on a large scale. This paper gives a solution to the control system of the multiphase matrix converters for power system application. The practical application of multiphase matrix converters (MC) in power systems involves the study of application requirements, possible converter topologies and the development of new, reliable control algorithms. The MC is working as a connection device between power systems or as an interconnection device within the power system. The proposed tasks performed by the MC in the power system are power flow control and power flow oscillation dumping. The device can be viewed as new FACTS device-series power system connector, based on straightforward energy conversion.

The article shows a new field of application for the matrix converter (MC) as the interconnecting device between the high speed, permanent magnet generator and the grid. The converter works under the developed control algorithm based on a so called ‘area based’ approach. The device consists of a converter, a transformer (or transformers) and filters and is supposed to substitute or revolution decreasing gear box or DC link based power electronic converter. Several structures, including multiphase structures (3, 12 phase) were investigated and their properties were assessed using the results of Matlab Simulink based simulations. The simulations were performed using the standard Simulink models and the developed, simplified permanent magnet motor model. The results were very satisfactory, i.e. input waveforms distortions, output current and machine torque ripples were at acceptable levels for the multiphase structures and high frequency input. The waveform distortions were found to be a function of input frequency and the number of phases in the conversion device, but the structure of the converter was limited to a 12x12 structure for economic reasons.

This paper presents the process of the development of the real life laboratory model of the five node power system of closed loop structure. The model was built using ‘power’ scaling and taking into consideration the parameters of the 400 kV lines built in the Polish National Power system. After the three-year development of the model, the parameters of the elements of this model were gained or obtained using classic identification procedures. During this part of the research, some differences between the parameter values given by the manufacturers and those obtained through identification procedures were reported and analyzed. The Matlab/Simulink model of the laboratory setup was then built to emulate the system behavior during dynamic states. The comparison of the currents, voltages and generator speeds proved to be simple tasks since the shape of the short-circuit current waveforms, for example, depends not only on parameter values but also on the time of the fault occurrence with respect to system voltages. Thus, the time responses of the laboratory and Simulink models were compared to evaluate time constants of the post fault processes.