Harmonic current interaction at a low voltage customer's installations

The increased uses of power electronics and switching devices in the electricity network have changed the operational environment of the power system. These devices have nonlinear voltage-current characteristics and produce harmonic currents, and consequently distort the voltage waveform. A low voltage domestic customer can have mixed loads that consist of linear and non-linear loads such as home appliances and lighting devices. In the PQ laboratory of TU/Eindhoven, the harmonic fingerprints of various household devices are measured. A LV household customer’s installation, consisting of various home appliances, is simulated in the network analysis tool ‘Power Factory’. The measured harmonic fingerprints of the connected devices are fed in to this software to perform harmonic simulations. The simulation results give the total harmonic current distortion level at the installation and the combined harmonic current interaction effects of different household devices. Furthermore, a case study is done to evaluate the total current harmonic distortion level at a customer’s installation when the grid voltage is polluted with a specific order of harmonic (such as the 5th harmonic). This is expected to be a typical futuristic scenario when many non-linear devices would be connected in the network and would distort the supply voltage.