Short-circuit ratio index of new energy grid-connected system with DC feed

With DC increase of large-scale proportion and new energy in power system and rapid development of new energy power generation technology and DC transmission, the characteristics and power grid stability have changed, and it is urgent to put forward a scientific and perfect short-circuit ratio index for systems stability of DC and new energy grid-connected. Based on the superposition theorem, the definitions of SCR<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">edi</inf> and SCR<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">edi-U</inf> of new energy grid-connected points are proposed, taking the interaction between new energy stations and DC lines influence into account. Secondly, according to the definition, the theoretical derivation of the critical short-circuit ratio is carried out, and specific value is given. Finally, the model is built on the PSASP platform, and the rationality, effectiveness and feasibility of the proposed indexes SCR<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">edi</inf> and SCR<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">edi-U</inf> are verified by simulation examples.