I had asked this question to PTI Siemens and I got a response from them which is :
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If the HVDC models called via CONEC and CONET subroutines (if this is the case you will see these hvdc models being called in conec and conet files with some hardcoded numbers as arguments), there is not any API to access the starting VARs etc (the reason being that PSSE generates these model calls and no information about such models is retained) If these models are called in conec and conet, these can be converted to a non-conec form. Once you do this you can, depending on whether the hvdc is a 2-terminal, or muli-terminal or a VSC dc line, use one of the APIs (DC2MIND, DCNMIND, and VSCMIND) to access the starting VARs etc.