A DECOUPLED 2ND-ORDER STATE ESTIMATOR FOR AC-DC POWER-SYSTEMS

This paper presents a new framework for decoupled state estimation of ac-dc power systems. Decoupling is not done by zeroing the off-diagona l submatrices of the Jacobian and gain matrices but as a two-step proc edure. The mathematical model involves both the first and second order derivatives of the performance equations. Only diagonal blocks of the gain matrix are required to be factorized, and they remain constant i n the iterative solution scheme. Their size and structure are similar to those in the fast decoupled state estimator which is based on the l inearised version of the Taylor series equations. Test results are pre sented, compared and discussed. The proposed method performs satisfact orily and its computational requirements are comparable with those of the fast decoupled state estimator.