Impact of External Distortion Sources on Harmonic Voltage Profiles of Consumers

The study assesses how nonlinear electrical loads of external consumers connected at the point of common coupling impact the electrical installation of a small-scale enterprise. The nonlinear electrical load of the traction substation is considered as an external nonlinear load while the electrical installation of the enterprise represents a low-capacity consumer. The developed analytical expressions enable the assessment of external distortion impacts, considering the network short-circuit power at various points, along with the nonlinear and linear load of the low-capacity consumer represented by induction motors. The study reveals that the linear load of the consumer under study has a significant shunting effect, reducing voltage harmonics from the nonlinear electrical load of external consumers. The findings also indicate that the voltage harmonic distortion factor scales with the nonlinear load power of the traction substation, which can be determined using the derived analytical expressions. The introduced criterion enables a preliminary evaluation of the harmonic level, characterized by the ratio of the short-circuit power at the transformer secondary to the transformer capacity. The analytical calculation results showed strong agreement with the MATLAB/Simulink simulations.