Effect of bad measurements on state estimation in power system

State estimation technique provides an estimate of the system state which is a phasor of the voltage magnitudes and angles at different nodes or buses of the system. Various measured quantities-power, voltage and current are analog quantities which are passed through A/D converters, and then digital outputs are telemetered to energy control center over various communication links, where these are processed to find present state of the power system. The process involves imperfect (bad) measurements that are redundant and estimation process of the system states is based on a statistical method that estimates the true value of the state variables. Though errors (imperfect measurement) should be reduced by the state estimation, the reliability of estimated data will reduce when some bad measurements are present in the system. Available data output at energy control center are then used to find the system performance in real time for system security and conditions of economic dispatch. In this paper simulation results of state estimation using weighted least squares method are being discussed for a 30-Bus System under static condition.