Iterative Linear State Estimation Using a Limited Number of PMU Measurements

State estimation (SE) in transmission systems is commonly carried out based on the supervisory control and data acquisition (SCADA) system measurements. The solution involves a recursive process due to the non-linearity of the measurement equations. However, the SCADA-based SE is prone to ill-conditioning which may lead to convergence issues. This paper presents an alternative and computationally robust method which uses primarily SCADA measurements plus a limited number of voltage measurements provided by phasor measurement units (PMUs). This is accomplished by first converting the power flow measurements into equivalent current phasors followed by a linear state estimation solution. Instead of updating the jacobian and gain matrix in each iteration, in this approach, the current phasors will be updated using the estimated phase angles from the previous iteration. Numerical examples will be presented to illustrate the performance of the method when applied to typical power systems.