A method for optimization of the working point of the N‐phase (N+1)‐wire systems with nonlinear loads

Abstract

Purpose

The paper proposes to deal with the problems concerning the N‐phase (N+1)‐wire system with sinusoidal voltage sources and nonlinear loads. In the model of the N‐phase voltage source the inner impedance has been included. The problem of the optimization of working conditions of the system is a minimization of RMS value of its line currents as well as their distortions caused by nonlinear loads.

Design/methodology/approach

The solution of this problem is based on the frequency domain. It is obtained by means of Lagrange's multipliers and the suitable measurement experiment.

Findings

After optimization source currents are sinusoidal with minimized RMS values. After connection of the designed compensator to the system under research the phase currents are equal to determined active currents.

Research limitations/implications

This method can be used for some classes of nonlinear loads, i.e. for systems with inertialess (non‐reactive) elements, which consume the active power of the basic harmonic of the voltage source and where the currents of the system are periodical. The mentioned power is an additional constraint of the presented minimization.

Practical implications

The working point of the system can be obtained by means of the compensator LC, RLC or (RLC,‐R). It will always be a linear one and its structure consists of two components: elements with parameters determined for the basic harmonic and the filter for elimination of the higher harmonics caused by nonlinear loads.

Originality/value

The presented method has been generalized for N‐phase (N+1)‐wire systems.

Citation

Debowski, K. and Pasko, M. (2007), "A method for optimization of the working point of the N‐phase (N+1)‐wire systems with nonlinear loads", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 26 No. 4, pp. 1123-1133. https://doi.org/10.1108/03321640710756447