New technique for enhancing the accuracy of HVDC systems in state estimation

•We describe a new technique for enhancing the accuracy of HVDC in state estimation.•The HVDC model consists of switching devices and identifies the operating mode.•The DC current is defined as a state variable to estimate the HVDC systems.•The fast-decoupled WLS is calculated based on modified gain matrix w.r.t DC current.•The algorithms verify through comparative test between Korean EMS and existing EMS.

This paper describes a new technique for enhancing the accuracy of high-voltage direct current (HVDC) systems in the state estimation of the Korean energy management systems. New methodology, which includes the accurate modeling of the HVDC systems using switching devices, the determination of the operating mode of the HVDC systems, and a fast-decoupled weighted least square approach with a modified gain matrix, is proposed to enhance the accuracy of state estimation. Especially, the DC current is defined as a state variable to estimate the HVDC systems. These algorithms are verified in on-line environment. The test results show that the proposed algorithm operates correctly for various situations.