P28/2 – Voltage Fluctuation Studies

P28/2 or voltage fluctuation studies are applicable to a wide variety of plants and a key regulatory requirement of DNOs, to ensure that a private network does not adversely affect the public network by creating problems of voltage flicker, or problems for voltage regulation.

The studies are primarily carried out for generation projects and battery storage projects to check the Step Voltage Change (SVC) associated with generation trips and the Rapid Voltage Change (RVC) associated with transformer energisation and battery storage unit power swings. However, they are also applicable to sites with large fluctuating loads such as large pumps and compressors, arc furnaces, winders, and so on.

Where things get really interesting is for battery energy storage projects. These are a new (for DNOs) type of project that are making many DNOs nervous. Traditionally BESS units were assessed considering power ramps from full import to full export, and full export to full import over a 1s duration – however it is becoming clear that such an approach is really a bit too simplistic. At Aurora we developed a standalone controller which can be used to replicate any of the standard DC / DR / DM services and then developed a method to generate a typical frequency disturbance profile based on NG ESO historical data. We will do a more detailed post on that next week, but its some clever and interesting stuff.

  • Transformer Energisation
  • Step Voltage Change (SVC)
  • Rapid Voltage Change (RVC)
  • Battery Storage Power Ramps
  • Battery Storage DC/DR/DM response
  • Large Load step and change factors
  • Flicker (Pst & Plt)

Aurora can carry out a detailed P28/2 voltage fluctuation assessment for any type of site, using either DIgSILENT Powerfactory or ETAP. If you want to know more – please get in touch