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RGE trip to full DNO supply

Hi all, Just after peoples thoughts on the following....


We are currently working on a scheme where our client is looking to install 2No. 2MWe RGE to offset the cost of the DNO supply. As part of a study we are conducting we are looking at how the system would react if the 2No. RGE's were to trip and the 4MWe load would be presented onto the DNO network which is already supplying a small portion of the sites demand.  Our aim is to confirm the main HV breakers do not trip or at what load share threshold they don't. 


We are conducting a load flow and fault level analysis using SKM PTW, but this only allows us to look at steady-state scenarios and not a live peak of supply demand. 

My first thoughts are that the HV breakers should be fine as the site will already be up and running i.e. no large motor loads starting or TX inrush, but just want to get other peoples thoughts on how they might approach the subject. 


Thanks
  • Former Community Member
    0 Former Community Member
    The most likely issue may be voltage more than thermal. Assuming that you can import 4MW, which the DNO will let you know. If not, you may have to add a demand disconnection scheme.


    But on a more realistic footing. At 4MW you will be connected at the MV level rather than the LV, most likely 11kV, but could be 33kV. At this level the voltage step change for any generator or load is 3% - defined by ENER P28. Meaning that the largest voltage step allowed (when the generator disconnects and the load is seen by the network) cannot exceed 3%.


    Most of that will come down to how strong a connection there is with the distribution network


    Hope that helps
  • Former Community Member
    0 Former Community Member
    Hello Jordan,


    I would recomend using the SKM PTW program I*SIM to model the dynamics as you say you have one of the PTW Fault programs already?.  It also depends on what kind of trip you are talking about.  If it is a prime mover overload and the generator rundown energy is available, it will assist with preserving the DNO supply stability.


    What kind of faults are you considering?


    Kind Regards

    Geoff MacAngus-Gerrard
  • Hi Michael/Geoff, 


    Thanks for taking the time to reply...


    You are correct the REG's will be connected at 11kV level, at this level we have 2No. switchboards and downstream we have 6No. TX which feed the LV systems. We have updated DNO in-feed fault data as they are moving our supply to a better structured side of their network. 


    We will be modelling load flow for approx. 6No. different scenarios and the emergency trip from both RGEs will be among these. 


    Yes we are using SKM and the ISIM may have some value thanks for putting me onto this.