Analysis of harmonic distortion generated by PWM motor drives

Abstract

This paper evaluates the harmonic distortion generated by PWM motor drives in an electrical industrial system of a wheat flour mill company. For this, a comparative study between two industrial circuits connected at the same point of common coupling with similar characteristics of load and transformers is presented. The difference is that one circuit has PWM motor drives and the other does not have them. In the study, a practical method based on the statistical characterization of the total harmonic distortion of voltage (THDV) and current (THDI), individual voltage distortion (IVD), individual current distortion (ICD) and K-Factor is applied. As result, it was observed that PWM motor drives generated harmonics voltage mainly of fifth and seventh order with values that exceed limits established by standards in both circuits. In the work is also demonstrated that in the analysis of harmonics is necessary to consider various parameters and not only one.

Frequency response analysis under faults in weak power systems

“…Equation set from (1) to (9) allows to obtain machine rotor speed and position while known its terminal voltage, which must be calculated from system electrical network solution by using load flow equations. For this, nonlinear differential and algebraic equations solving numerical methods can be used, which allow calculating and performing system voltage and frequency behavior in disturbances presence (15) is obtained from (4) and ( 5) which means currents can be calculated as follows:…”

Monitoring Single-Phase LV Charging of Electric Vehicles

“…Power quality disturbances that occur in the power grid and affect the reliability of electrical machines include, among others, voltage fluctuations [ 11 , 12 ], voltage distortions caused by higher harmonics [ 13 ] or inter-harmonics [ 14 , 15 ]. At the same time, in some cases, the operation of electric machines or devices associated with them can also cause disturbances of power quality [ 16 , 17 , 18 ], for example, the electric machine control or the charging of an electric vehicle (EV) [ 19 , 20 ]. The consequence of the appearance of the reduced power quality is the reduction of the reliability of other loads (including electric machines) supplied from the same power grid.…”

Voltage collapse point evaluation considering the load dependence in a power system stability problem

“…Many of these indices require only the steady-state modeling of the EPS, which decreases the calculation time and this is one of the advantages over the analyzes that involve the dynamic modeling of the EPS [7]. One aspect to take into account in studies of voltage stability is the behavior of the load and its influence on this phenomenon [15][16][17][18]. The tools for the simulation of the stability problem consider the load to be constant, when in reality it depends on the voltage and the frequency [19].…”