What is the purpose of a load flow study?

Load flow studies are one of the most fundamental study types carried out as part of system analysis; but they are often ignored by companies as they are seen as a bit wooly and non-essential. However, they are actually very useful and tell the designer a lot of useful information, as they are used to show how the system will operate in normal, and outage conditions. Whilst this may seem obvious, these studies show a wealth of key information such as equipment loading (over or undersized transformers or cables), voltage profile across the system, which in turn lets transformer tap positions be set, generation adequacy, system losses, active and reactive power flows, power factor at the point of connection and the need for any MVAr compensation.

The other useful part of loadflow analysis is that on large systems it lets you run and analyse multiple and complex outage and emergency cases. This allows identification of bottlenecks and weak point that may not be obvious in everyday operation.

The studies do not have a formal standard to follow in the UK, and are not essential from any legal point of view, but are very useful. Loadflow studies typically consider the following issues:

• Steady state analysis
• Ring open point check validation
• Equipment rating
• Voltage profile
• MVAr compensation
• Power Factor check
• Emergency condition loadflow