Marchwood Power Station — Grid Code Compliance
2 x 334 MVA gas turbines, 1x 346 MVA steam turbine, 400 kV connection
The challenge
Synchronous plant at 400 kV is a different proposition to inverter-based generation. The dynamic behaviour of the unit is dominated by the governor, AVR and limiter response, and standard off-the-shelf models do not cover everything the Grid Code asks for. In particular, the OEL, UEL and SCL behaviour had to be represented at a level of detail that the standard model libraries did not provide.
What Aurora did
We built detailed DIgSILENT PowerFactory and PSCAD models of GT11, GT12 and ST12. The machine governor was implemented using a GGOV1 model partially developed within PSCAD, the AVR was an ST9C, and the OEL, UEL and SCL were all written as custom models tuned to the actual plant characteristics. The models were used to deliver Grid Code compliance evidence covering GC0141 and PC.A.9 requirements for both RMS and EMT analysis, with results cross-checked against earlier site commissioning tests.