A Method for Predicting the Level of Lighting Network Harmonic Components in Terms of the Coefficient of Nonlinear Current Distortion of Lighting Electrical Appliances with Respect to the External Factor Effects

The article is devoted to the analysis of relations between the level of harmonic current components in local low-voltage lighting networks and the initial parameters of lighting devices of various types connected to it and various external factors. The purpose of the research is to study the relation of the initial nonlinear current distortion coefficient of lighting electrical appliances with respect to various parameters and develop a universal method for predicting the real level harmonic components for a circuit portion based on these values. The paper presents the results of experimental measurements of main characteristics and coefficients of nonlinear current distortion of various linear and nonlinear lighting devices. The relation between their values and a number of external factors has been studied: the total power grid load, the time of day, the power grid non-sinusoidal voltage, the distance to the source of higher harmonics emission from the control point and various types of electrical appliances connected in parallel to the power grid. As a solution, a formula for calculating the predicted level of harmonic components of the lighting network with correction coefficients for each practical case providing prediction the level of possible power grid loads based on laboratory values of lighting devices and selection effective solutions to maintain electricity quality at minimal cost is proposed. It is suggested to call correction coefficients as the “distance coefficient” responsible for distance correction of the connection point of special filter-compensating installations (FCS) from the source of higher harmonic emission, the “non-sinusoidal voltage coefficient” that takes into account the current state of sinusoidal voltage in the network, and the “mutual reduction coefficient”, which approximates the objectivity of estimating the total harmonic components of a circuit section by the coefficient nonlinear current distortion of each device. The results obtained make it possible to predict the actual level of harmonic loads of local lighting networks based on the parameters of the connected lighting devices and the characteristics of the power grid for the selection of optimal filter-compensating installations reliably.