Soft-open points for medium voltage networks – A case study

Abstract

Using soft-open points (SOP), the load flow and fault behaviour of a distribution network can be decoupled. This is appealing when addressing the impact of distributed infeeds. This paper introduces two possible control strategies for an SOP: the switch and the PQ modes.The addition of an SOP to two illustrative MV networks (urban and rural) is investigated: the SOP can contribute to reduce voltage variation and peak grid component loadings in both situations. As a consequence of the higher voltage variations in the rural example network, a voltage controlled mode or PQ controlled mode appears more appealing to this situation. An SOP with a reduced rating can also contribute to a partial improvement: when the SOP is used to reduce voltage variations and grid component overloading to a given quality standard, only the excessive variation or overload needs to be compensated.The paper presents a modelling framework that will be used in a demonstration project where a reduced scale SOP will be deployed into a real network.