Protection issues in the presence of power electronic converters in smart LV residential networks

Abstract

The use of a power electronic converter to step-down the voltage at the point of connection to individual residential houses is being considered in the UK. This is so that the voltage on the existing low voltage cables can be boosted, which would result in an increase in capacity without the need for costly reinforcement. This capacity increase is needed to accommodate an anticipated take-up of new, low-carbon technologies such as electric vehicles and electro-heat. The inclusion of a power converter and communications device also offers the opportunity for smart-grid functions such as managing local demand through voltage control. This study considers the design of this converter within the context of wiring regulations and standards that currently apply to a residential property. In particular, it is found that the rating of the converter is determined by the need to co-ordinate with the existing circuit breaker protection within the house. A protection strategy is therefore proposed for the converter, which is evaluated using a statistical simulation study.