State Estimation of a Utility-Scale Hybrid AC/DC Grid using a Decentralized Approach

The main focus on the renewable energy resources to meet out the energy demand of the customers by integrating these generations with the AC grid on the Transmission end has necessitated to the maintenance of the voltage magnitude, phase angle and frequency within the specified limits. This challenge is aided by power system state estimation. The power system state estimation is the process of entrusting a value to an unknown system state variable based on measurement from that system according to system conditions. This paper presents a decentralized state estimation technique to estimate the state of a utility-scale hybrid AC/DC Network. The hybrid test system is formed by integrating the 5 bus DC system into IEEE 24 bus Reliability Test system which is taken as test case. The Weighted Least Square (WLS) method is used to perform the state estimation problem for the hybrid system in a decentralized manner. The state variables of hybrid system are estimated by using DIgSILENT software. The values obtained from the test case are compared with the true values which are taken from the conventional load flow measurements. The accuracy, convergence, normalized error and robustness of the test system are also analyzed.