Modified Newton and fast decoupled load flows for tracing power systems bifurcation diagrams

The conventional Newton and fast decoupled load flow methods are considered to be inadequate to obtain the system´s maximum loading point due to ill-conditioning problems at and near this critical point. At this point the Jacobian matrix of the Newton-Raphson method becomes singular, and the P-V and Q-/spl theta/ decoupling assumptions made for the fast decoupled load flow formulation no longer hold. However, results obtained for the IEEE systems (14, 30, 57 and 118 buses) have shown that appropriate modifications in the above methods make them adequate for the computation of the complete bifurcation diagrams. Besides, the characteristics of the conventional methods are preserved.