Sorin G. Pavel

Street lighting power quality

This paper presents the general aspects of the theory of power quality analysis and the mathematical description of the main parameters which are listed in the paper. Since the proper functioning of electrical equipment depends on network voltage harmonics and current waveform, an investigation of urban street lighting in this regard is beneficial.

Nomograms for sizing the vertical earth grounding

The design of earth grounding at rated values corresponding to the role to be accomplished is relatively laborious and there are no highlighted optimum criteria giving the justification for the chosen solution. The vertical earth grounding calculus is restructured in this paper, realizing sizing nomograms which include all characteristic sizes, the final goal being the determination of the electrodes number which ensures the rated value achieving for the dispersion resistance. For the designing simplification, the unitary earth grounding is defined versus which the earth grounding may be easily finalized with different values compared to the unitary one. The dispersion resistance determination for the simple earth grounding with only one electrode is considered as the first step in earth grounding sizing, for which a calculation nomogram was conceived. The second step is represented by the electrodes number determination for the multiple earth grounding which leads to the obtaining of the rated value for the earth grounding dispersion resistance.

Survey regarding additional indicators for voltage sags

Voltage dips represent a Power Quality disturbance with the most significant economical consequences. However, too few of their characteristic sizes are defined, such as voltage sags amplitude and frequency. A new series of characteristic sizes for the voltage sags are justified presented in this paper, forming together with the already known a complete indicators family, for this aspect of Power Quality disturbances. Also, here are analyzed and proposed the voltage sags main shapes, for their recognition and classification.

Vertical earth grounding design using optimal criteria

Properly sizing of earth grounding is a current issue of designers, because successive iterations required, which are determined by the nonlinearity calculating relations on the one hand and their complex structure, on the other hand. Continuing sizing methods improvement of the earth grounding, the paper applies three optimization criteria targeting the footprint minimizing, the total volume and mass of the earth grounding conductive elements. Identifying an analytic function for f(ne) which introduces the use coefficient dependence of the electrodes number ne, known so far only tabular allowed a more extensive analytical treatment of the suggested optimal criteria. The obtained results led to some observations and conclusions that can have significant technical and economic effects, in the earth grounding optimal design.

Real-time robust controlled driving system with permanent-magnet synchronous motor

This paper is concerned with robust vector control of a permanent magnet synchronous motor (PM-SM) using a fix-point DSP based computing architecture. Speed control systems are analyzed for different operation conditions. A hardware architecture was developed based on a TMS320C5x fixed-point processor, a PWM control unit realized in FPGA technology, an interfacing unit to the incremental encoder and A/D converters for the stator-phase current inputs, a high speed TDM-type serial bus and an emulating and debugging driver. The software was written in both, DSP-assembler language for acquisition and communication programs and in C language for the control algorithm computation. The computing system solution based on a minimal hardware configuration offers a flexible solution for different control strategies applied to a large scale of driving systems.

Optimal design of vertical earth grounding, with rectangular perimeter

In previous papers, the authors have resumed the earth grounding dimensioning with the intend to propose optimum criteria and to simplifying the design procedure. Five general characteristic sizes for the earth grounding have been proposed that may be in as many objective functions. Of these, the footprint area, the total metallic mass and the earth grounding volume have already been approached with particularly encouraging results. Firstly, a summary of the application for the first three optimum criteria is presented, for the case of the vertical electrodes placement after a rectangular outline. This paper brings results referring to the application of the other two optimum criteria such as dispersion surface area of the earth grounding elements and the earth grounding investments costs. In addition, this is made with considering the contribution of the connection conductors between the electrodes, to the total dispersion resistance of the earth grounding. In this way, the data from tables and figures constitute useful guidance for designers, significantly reducing the optimum solution searching range. It is also presented the algorithm through which was established the electrodes number which lead to accomplishment of the proposed earth resistance. The specific costs used for the investments costs criterion can present some evolutions in time but given that different components ratios of expenditure present a relative constant, the optimum solutions validity identified through this criterion is maintained in time.

Graphic functions analytical identification at flicker evaluation

The flaring phenomenon or flicker is framed with no less than three indicators for which there are normalized values. The methodologies for determining indicators as flicker dose and severity as well as the voltage fluctuations limits use graphic functions, experimentally determined. A LabVIEW original program is used in order to identify the optimal analytical expressions for graphic or tabular functions like graphic functions from the flicker evaluation. It aims, on the one hand, to make easier the software implementation of the flicker indicators calculation methods and on the other hand to ensure their analytical handling. Simple expressions identified for graphic functions, relative to flicker, present acceptable relative mean square deviations, which allow the flicker dose determination with the required precision. Also, comparing the voltage fluctuations amplitudes with standardized values can be directly made, on an analytical way.

Fundamentals of slow voltage variations analysis

The power quality (PQ) indicators, related to slow voltage variations, are expressed usually both absolute and relative values. Consequently, the paper presents the complete family of slow voltage variations indicators in expression of absolute, relative and percentage. The necessity of an expressive analysis of voltage variations led to idea of the voltage wave decomposition in actions and harmonics that represents a new concept of voltage variations analysis. The unitary step actions are equivalent to an infinite harmonics numbers whose interpretation detached from context, would be meaningless. In terms of electric power systems these actions are found in the interventions of the dispatcher, supplier or end-user for maintaining the rms voltage within limits. The highlighting of voltage wave levels and then the harmonic analysis of the variations which it presents is proved to be the most accurate method of slow voltage variations analysis. Also, a measurement extending upstream the point of interest represents another contribution to an expressive voltage variation analysis. Overall, the paper offers a new analysis base for causal interpretation of voltage variations in a network point of interest.

Optimal analytical identification of the photometric curves for the indoor direct lighting luminaires

Luminaires new catalogues highlight permanent changes in their technology and equipment, determining deep implications on the distribution of the emitted luminous flux. Using the index of correlation between the indoor luminaires photometric curves (Philips) and those defined through the functions from the BZ classification, indicates that some of the first category are not included among those from the BZ classification, requiring new types of functions. The original program realized in LabVIEW by the authors in order to obtain the analytical identification of some graphically or tabular known functions was successfully applied for modern luminaires photometric curves, resulting simple functions and reduced errors, in most cases. The program improvement and the carrying on of the analytical identification of the photometric curves and bodies aim to define a standard for an easier transmission of the luminaires photometric characteristics.

Comparative evaluation of vector control versus direct torque control for PM-SM drives

Based on previous research experience proved by simulated and experimental results a comparative discussion about advantages and disadvantages of using Vector Control or Direct Torque Control for PM-SM drives is presented.