Computing saddle-node and limit-induced bifurcation manifolds for subtransmission and transmission wind generation

This paper introduces an exact and efficient method for computing and visualizing the power flow feasibility boundary of large networks composed of (1) saddle-node bifurcation manifolds where the Jacobian is singular and (2) limit-induced bifurcation manifolds where the network loses structural stability as the limit is encountered. This method is applied to the DTE/ITC system in Eastern Michigan where significant wind development has taken place at both transmission (120-345kV) and subtransmission (42kV) levels. It is shown that reactive compensation capability of subtransmission wind farms, in voltage control mode, can shrink the feasibility boundary and hence negatively impact the voltage stability margin of the system.