AC/MULTITERMINAL DC POWER SYSTEM STATE ESTIMATION-A SEQUENTIAL APPROACH

Abstract

ABSTRACT This paper describes a simple, efficient and flexible optimal method for estimating the state vectors of integrated multiterminal HV dc/ac systems. The approach adopted is sequential in nature in which the ac system is solved followed by the dc system. A six variable model to represent the interface and the dc subsystem is utilised. The dc subnetwork is modelled by a conductance matrix. For each converter six pseudomeasurements, twelve actual measurements are considered, in addition to the actual power and current flow measurements in the dc network. A Fast Decoupled State Estimator based on sparsity-oriented bifac-torization technique with scheme two ordering, is developed and used for solving the ac system. To save memory and computer time, dc system is also solved employing sparsity technique. Performance of ac/dc state estimator is investigated incorporating a mesh-connected dc network in IEEE 14 bus ac system. The proposed algorithm successfully works for obtaining the optimum state of ac system, ac system with dc link and ac system with multiterminal dc network. Since it is very fast, it is suitable for on-line operations.