Voltage collapse and its avoidance

This paper discusses the phenomenon which leads to voltage collapse. It describes how automatic control equipment may exacerbate the decay of system voltage levels, with specific reference to the automatic tap changing of supply transformers. It addresses the factors which affect the onset of such behaviour, and operational requirements for the avoidance of voltage collapse. Reference is made to on-line algorithms which could be used to provide advice to power system control engineers which would help them avoid voltage collapse by making the most effective use of reactive resources.