Experiences in State Estimation at the Australian Energy Market Operator

State estimation has been fundamental to the operation of the power systems and markets in Australia for over two decades since the inception of the Australian Energy Market Operator. During this period, the challenges faced in state estimation have been many and varied, not only because of the growth of the power system network but also by the demands of the expanding number of analytical tools that depend on it. More recent challenges involve the rapid transformation of the Australian power systems from traditional synchronous generation to inverter-based resources as well as the introduction of new technologies such as grid scale batteries, the introduction of phasor measurements and the increasing penetration of embedded residential rooftop photo-voltaic resources. Along this journey the state estimator, together with the network model, has been enhanced and tuned to meet these emerging challenges. Several techniques have been employed to ensure that the state estimator and subsequent network applications remain sufficiently reliable and accurate for AEMO to maintain situational awareness and to operate the power systems and its markets within the required standards.