Hi Matthew, as AMK says, reactive power helps keep the voltage to the nominal levels for the system (400kV, 275kV, 132kV…) if there is too much or too little the voltage can stray above or below the target voltages. In the UK, the grid stability varies depending upon where about in the country you are. I’m in the north of Scotland where the grid stabiltiy is weak due to a number of factors, but mainly due to being far away from large generators that as well as producing electricity, help control the voltage. 
Further down into England where there are large pools of industry, which would be starting up at the begining og f the working day and shutting down at the end can also have an effect on the voltage level and the reactive power. Lots of motors all starting around a similar time, lots of people waking up and starting their day all has an effect on the demand and how the voltage stabiltiy is maintained. 

There are also other factors that can affect the voltage such as demand and supply but these are less influenced by reactive power availability. 

Hi Ollylee21, interesting discussion. I am curious to know more about how you and your colleagues manage the voltage levels and the reactive power in the north of Scotland, and what kind of solutions or innovations you are working on or planning to implement. 

Hi Ollylee21, interesting discussion. I am curious to know more about how you and your colleagues manage the voltage levels and the reactive power in the north of Scotland, and what kind of solutions or innovations you are working on or planning to implement. 

Hi AMK, in the north we use various plant to try and regulate the voltage, mainly STATCOM/SVC, Reactors and Quad boosters.