Modern state estimation methods in power systems

State estimation is an important tool for system operators. The state of the power system is defined by the voltage magnitudes and phase angles at all buses. The state estimator (SE) determines this state based on a set of redundant measurements. The classic steady-state estimator is widely used. Attempts to formulate a dynamic-state estimator have also been made. To speed up the computation, some authors have tried to formulate a distributed SE which can be computed using parallel processing. Recently it became possible to do very accurate synchronized phasor measurements. Now state-of-the-art SE are implemented using data from these measurements. This paper gives an overview of the power system state estimation theory and practise. It is intended to serve as starting point for developing new state estimation techniques.