Steady-state voltage in low voltage networks

Steady-state voltage is probably the most fundamental of power quality disturbances and perhaps the most overlooked in terms of assessment and impact. Steady-state voltage is defined as voltage magnitudes equal to or relatively near to the system nominal voltage and the magnitude considered is the root mean square (RMS) value of the voltage waveform. The emphasis in this chapter is also on the management and impacts of steady-state voltage magnitudes in low voltage (LV) networks as this is where the majority of customers and their equipment are connected. There is obviously a very strong relationship between upstream voltages and LV magnitudes and this is dealt with where appropriate. This chapter primarily examines supply voltage magnitude in LV networks. Standards for voltage and nominal voltage used throughout the world are described first. The principles of voltage regulation are then introduced including voltage regulation with and without distributed generation. The impact of supply voltage magnitude on different equipment types as well as consumer electricity usage is then discussed. Finally, methods which can be used to improve unacceptable levels of voltage regulation in LV networks are described.