A partitioning strategy for improved state estimation performance in ill-conditioned power systems with hybrid measurement set

Yildiz T., AÇILAN E., GÖL M.

ELECTRIC POWER SYSTEMS RESEARCH, vol.201, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 201
  • Publication Date: 2021
  • Doi Number: 10.1016/j.epsr.2021.107515
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Environment Index, INSPEC
  • Keywords: State estimation, Fast decoupled state estimation, Hierarchical state estimation
  • Middle East Technical University Affiliated: Yes


Considering the increase in power system size and the number of PMUs, the utilization of a computationally efficient yet accurate static state estimator is crucial. The fast-decoupled WLS estimator (FD-WLS) is the most common method employed in industrial applications, thanks to its computational efficiency and ease of implementation. However, it is known that FD-WLS fails in the presence of an ill-conditioned power system, e.g., a power system with high R/X ratio and large difference between measurement error variances. This paper proposes a partitioning strategy for ill-conditioned power systems. The proposed method forms two types of subsystems, such that one can apply FD-WLS in the type-1 sub-systems, and conventional formulation of WLS should be applied in the type-2 sub-systems. The utilization of the proposed method enables a computational performance comparable to that of FD-WLS and an accuracy comparable to that of the centralized solution.