Reactive Power Exchange Application Capability Transfer (REACT)

Contact: Ben Marshall - box.innovationtransmission@nationalgrid.com

The proposed project formed the first building block required to answer the following two questions: 

• How can voltages at 400kV & 275 kV be kept within statutory limits? 
• What factors and trends are there that could be making transmission voltage control increasingly more problematic and/or costly under low load conditions and how do these influence reactive power? 

In addition, the project crucially allowed DNOs to understand the technical aspects to be tackled in order to comply with the European Demand Connection Code that will in a few years limit GSP exchanges to 0MVAr for load up to 25% of the GSP capacity.

Objectives

The key objectives were to determine: 

• The key factors behind the significant decline in reactive power demand and the corresponding increase in the DNO system reactive power gain as observed at the Transmission/DNO interface (i.e., Grid Supply Point). During periods of minimum loading the reactive power demand has reduced from circa 7500 MVAr in 2005 to 2100 MVAr in 2013. 
• The key factors behind the significant decline of the reactive to active power ratio (Q/P ratio) during periods of minimum demand. During the last 5 years, there has been a fall of 50% of the reactive power demand followed by a corresponding nonproportional fall of 15% of the active power demand. 
• The relationship of all factors affecting the decline in reactive power demand at these interfaces during the same periods. 
• The link to the upcoming requirements from the European Demand Connection Code changes expected in Demand Connection Code.

Expected Benefits

The success criteria is defined as: 

1. Industry accepted solution for managing PIV uptake on distribution networks that will avoid significant infrastructure costs or disruption 

2. Industry accepted customer messaging strategy and recommendations for implementation

• Documents and links

  Closedown Report