Fast decoupled state estimation including thyristor controlled series compensator devices*

This paper extends the weighted-least-square state estimation (WLS-SE) formulation to enable the solution of networks with embedded thyristor-controlled series compensation (TCSC). In the proposed methodology, the TCSCs reactances are treated as new state variables along with the complex voltage at the network nodes. Information regarding the specified active power flow through transmission lines connected to TCSCs and net power injection at their connecting nodes are strategically modeled as new active and reactive pseudo -measurements to be included into both: the linear and the fast-decoupled WLS-SE problem. Applications of the proposed extension in connection with the exact solution of a TCSC embedded power flow algorithm are presented and discussed. The IEEE 14-and 118-bus test systems are employed to illustrate and evaluate the proposed approach. The results point out that the new tool is effective to accurately estimate the system states and the control parameters of the TCSCs under distinct operating conditions.