Characteristics and Parameters of a Three-Phase, Three-Wire Balanced Circuit with Non-Linear Load

Abstract

The existing non-linear load in a three-phase circuit limits the possibilities of using the symmetrical components method to analyse it. This paper presents a method for analysing such a circuit when only the zero and positive components are present. Nonlinear loading in a circuit limits the applicability of the symmetrical components method in the analysis of a three-phase circuit. When there is only a zero component and a positive component, it is possible to carry out the analysis as presented in this article. The analysed circuit is balanced. An equal nonlinear load with a voltage described by a signum function of the current is considered in three phases. This load, through equal series RL elements, is supplied from a symmetrical three-phase voltage source. For a steady state with unbroken current flows, the equations of the circuit are solved symbolically. In the broader scope of the equation, solutions obtained using MATLAB-Simulink R2021b were used. The matching of the symbolic and simulation solutions was obtained. The current and voltage harmonic content coefficients of the receiver, the equivalent resistance and inductance of the nonlinear load, and the distribution of active and reactive power in the circuit were determined. The reactive power analysis shows that the considered load nonlinearity when generating higher harmonics, increases the reactive power of the circuit and the inductance of the circuit, which is seen from the terminals of the power source.

Keywords

• three-phase AC circuit
• non-linear load
• equivalent diagram
• inductance increase
• simulation analysis
• reactive power