A survey of harmonics in power systems of ships with electrical propulsion drives

The number of commercial ships with electric propulsion is in continuous increase due to their versatility and fuel efficiency. Total harmonic distortion consequences on marine electrical power systems will be discussed. This paper aims to highlight the need for harmonic filter implementation on electric propulsion with static converters. For this study, a simulation in Matlab Simulink will reveal the effect of electrical filters on THD and voltage end current waveforms.

Experimental Measurement of Conducted Emissions Generated by Static Converters in Common and Differential Modes

The commutation of semiconductors and their interactions with parasitic elements linked to the environment is known to be the main source of interferences conducted in power electronic converters. Thus, identifying these sources of interferences in commutation cells and determining the level of these conducted emissions generated in energy conversion systems presents a major challenge for designers. In this work, a study of the electromagnetic interferences (EMI) generated by the association of serial rectifier-chopper connected to a Line Impedance Stabilization Network (LISN) is proposed, in which a determination of these interferences is presented in both common and differential modes. All simulations are carried out using the LT-spice software and the results obtained are validated by experimental measurements realized at APELEC laboratory (University of Sidi Bel-Abbes, Algeria).

Contribution of Multilevel Inverters in Improving Electrical Energy Quality: Study and Analysis

The work proposed in this paper concerns the study of harmonic pollution generated by static converters, particularly inverters, which largely contributes to the degradation of the supplied electrical energy quality. So, we studied in first the EMC of the conventional two-level inverter to highlight the harmful pollution of this kind of converter. We then looked at multi-level inverters to characterize their degree of pollution according to their number of levels in order to propose practical solutions for industrial applications. Thus, we considered three structures of multi-level inverters namely: a diode clamped inverter, a flying capacitor clamped inverter and a cascaded h-bridge inverter. At the end of this study, we retain that these three structures make it possible to obtain a waveform of the output voltage close to the sinusoidal form. The results of simulation obtained and compared to the STD international standard templates, also allowed us to conclude that among the three structures studied the cascaded h-bridge inverter is the most interesting from the electrical energy quality point of view. In addition, this converter has the advantage of owning a reduced number of switches which results in a weight and a cost, better than those of the other two studied inverters.

ON THE ISSUE OF IMPROVING THE QUALITY OF ELECTRICITY IN THE TRANSIENT OPERATING MODES OF MARINE DIESEL GENERATOR SETS

The operation of diesel generator sets (DGS) under conditions of significant frequency deviations with sharp load changes is investigated. Systems containing powerful static converters in transient operating modes experience a sharp deterioration in the quality of electricity in terms of non-sinusoidal voltage. The use of filtercompensating devices in conditions of frequency deviation is not effective. In order to improve the quality of the transition process, it is proposed to reduce the speed (frequency) dips by increasing the inertial mass of the DGU by hanging the flywheel.

A Reliability-Exploitation Analysis of a Static Converter Taking Into Account Electromagnetic Interference

The paper presents issues associated with the impact of electromagnetic interference on static converters, which exploitation in a railway transport environment. The measurements of an electromagnetic field emitted by a static converter were shown. Designs of this kind are exploitation in railway facilities, therefore, they should not disturb the functioning of other equipment, the rail traffic control systems, in particular. As a result of the EMC tests, it was concluded that the permissible values of conducted interference emissions were exceeded. An analysis of the obtained results enabled developing a research model, and a further reliability and exploitation analysis, taking into account electromagnetic interference. This, in turn, enabled determining a relationship allowing to determine the probability of a static converter staying in a state of full ability. The presented discussions regarding a static converter, taking into account electromagnetic interference, allow for the numerical assessment of different types of solutions (technical and organizational), which can be implemented in order to mitigate the impact of electromagnetic interference on a system’s functioning.

Study of photovoltaic systems using modelling and simulation

The article presents mathematical models and simulation programs, made in MATLAB - Simulink, of the main components within photovoltaic system. For the continuous supply of electricity to consumers, in addition to photovoltaic panels are used electric accumulators and static converters, which have the role of converting direct current into alternating current or alternating current into direct current and to monitor and control the charging–discharge batteries process. The assembly consisting of all the elements presented above, interconnected and dimensioned to operate in a single system, is modelled and simulated and the results obtained reflect the limits but especially offers the possibility of choosing the optimal solution for a park of energy production based on solar radiation.