Prediction of harmonic voltage distortion when a nonlinear load is connected to an already distorted supply

Before an industrial consumer is allowed to connect a nonlinear load to a power network, he is often required to perform a calculation to predict the harmonic voltage distortion that will result at the point of connection to other consumers. When carrying out this calculation it is often assumed that the supply voltage waveform is a pure sinusoid before the load is connected. In fact the supply waveform is rarely sinusoidal and the voltage distortion observed after the new load has been installed will be due to the combined effect of the supply and load distortion. The concept of a statistical model to represent supply voltage harmonics is developed and its uses are demonstrated in conjunction with a model of load distortion, to predict the resultant voltage distortion