Queries about USRMDL keyword
I am trying to understand the purpose of the 'USRMDL' keyword present in the dynamic (.DYR) files of several models I've come across. Presumably, this corresponds to the 'user-defined' models that get adopted in the dynamic data. However, where is this user-defined model located? Is it a model built using the Graphic Model Builder in PSS/E Netomac? How can I find these User-Defined Models within the PSS/E interface if I don't want to code the .DYR file in a text editor?
I came across a .DYR file defining the dynamics of a wind power plant consisting of two different Type-3 wind turbine models. The first turbine has its dynamics defined in the 'DYR' file without the 'USRMDL' keyword, using REGCA1, REECA1 blocks. Whereas the second turbine has its dynamics defined in the 'DYR' file with the 'USRMDL' keyword, using REGCAU1, REECAU1 blocks, as shown below.
510111 'USRMDL' 1 'REGCAU1' 101 1 1 14 3 4 0
510112 'REGCA1' 1 1
Can anyone explain to me the significance of a user-defined model? Thanks in advance.