Centralized Versus Distributed State Estimation for Hybrid AC/HVDC Grid

Grahn, Pontus and Briggner, Viktor and Johansson, Linus and Babazadeh, Davood and Nordström, Lars
IEEE International Conference on Innovative Smart Grid Technologies, (ISGT Europe 2017)
The need of transmission grid expansion has drawnthe attention towards high voltage DC (HVDC) as a solution.This brings new challenges for power system control applicationsuch as state estimation that are originally designed for AC powersystem. This papers studies centralized and distributed architecturesfor hybrid AC/HVDC state estimator (SE). Furthermore,the benefit of having bad data detection (BDD) and deployingphasor measurement units (PMU) in the state estimation areinvestigated. The method used for the SE is the weighted leastsquare (WLS) method. The SE will be developed based on thepower grid model ’The CIGRE B4 DC Grid Test System’. Theresults of the tests show that the addition of BDD and PMUimproved the error of the estimated values. Furthermore thedistributed architecture offered slightly less accurate AC valuesthan the centralized.