Tracking Transmission Line Parameters in Power Grids Observed by PMUs

The paper presents a method to estimate the parameters of transmission lines using a minimum number of synchronized measurements. Considering the noise in the measured bus voltages and line currents, a phasor-only static state estimation is employed first to estimate the states. Then, the parameters of transmission lines are tracked dynamically by a Kalman filter. State estimation and parameter tracking are iteratively carried out to reduce the uncertainties that exist in the estimation function. A PMU placement algorithm is developed to ensure that all system parameters can be tracked accurately. Several tests are carried out on IEEE 14 bus system. Results of these simulations are provided to illustrate how the proposed approach can successfully track line parameters under a variety of operating conditions.

I. Introduction

With the increased penetration of stochastic renewable energy resources such as solar and wind power, new system operation strategies to deal with reliability issues are required. As one of the critical variables in power grid operation, transmission line capacity must be sufficient to handle the fluctuating power flows [1]. A number of proposed methods to deal with the impact of variable outputs of renewable sources, require accurate real time information of transmission line parameters. Many other network applications, such as protective relay settings, fault location and state estimation [2], also use transmission line parameters in their models. Hence, accurate knowledge of line parameters is a crucial requirement for reliable and efficient operation of future power grids.