Calculation of voltage fluctuation caused by intermittent loads

Abstract

Intermittent loads, such as grinders and welders, are the main factors that degrade the power quality in the distribution system. Intermittent loads will result in voltage fluctuations with stochastic characteristics, which may lead to malfunction of other sensitive loads. This paper uses cumulant method to calculate the bus voltage fluctuation using the algebraic addition and multiplication. The probability density function of the voltage fluctuation can be further expressed by the Gram-Charlier series expansion. Compared with traditional methods, computation complexity can be simplified and computation time can be markedly reduced by the proposed method. The simulation results from an 11-bus industrial distribution system with grinders show the applicability of the proposed method.

A new method with minimum number of monitoring points for flicker source tracing by wavelet transform

“…These fluctuations can be generated from heavy loads like welding machines, motors, and arc furnaces. [10][11][12] As well as, the wind farms and the solar photovoltaic system can also be considered as another voltage flicker source (FS). [13][14][15] According to IEC 61 000-4-15, 16 the human eyes can observe the voltage fluctuations more than a particular magnitude (up to ±10%) for certain frequencies ranged from 0.5 to 35 Hz as an annoying unsteadiness of the light intensity.…”

“…In general, voltage flicker is a periodical or fortuitous deviations of the voltage waveform. These fluctuations can be generated from heavy loads like welding machines, motors, and arc furnaces . As well as, the wind farms and the solar photovoltaic system can also be considered as another voltage flicker source (FS) .…”

A new approach for the simultaneous identification of the location and individual contribution of multiple flicker sources using the least number of monitoring points

“…Voltage flicker is the result of low‐frequency voltage envelope fluctuations and has received much attention due to numerous customer complaints 7,8 . Heavy loads such as furnaces, welding machines, rolling mills and motors are the main sources of voltage flicker 9‐15 . Moreover, solar photovoltaic systems and wind farms are other examples of voltage flicker sources 16‐20 .…”

Probabilistic harmonic load flow using fast point estimate method

“…In [11] a linear approximation method based on chance constrained programming has been presented which used for optimal planning of single tuned harmonics passive filters. Moreover, in [12] an approximate cumulant based method has been presented to calculate the bus voltage fluctuation using the algebraic addition and multiplication. To save the time and avoid calculating these derivatives, point estimate methods (PEM) have been developed which use approximate formulae to calculate the statistical moments of a random quantity [13, 14].…”