The predominant approach to solving the parameter estimation is the weighted least squares method. However， it's difficult to process gross errors in the measurement incorporated with the network parameter error and prevent numerical ill-conditioning using this method. Considering the fact that both bad measurement data and false network parameters may simultaneously appear in power system state estimation， a weighted least absolute value（WLAV） robust estimation based on the linear interior point algorithm and orthogonal transformation is proposed for augmented parameter estimation. The WLAV estimators based on the L1norm have good properties of bad data rejection and are exploited for mixed estimation of bad data / topology error and parameter error. The orthogonal transformation is introduced into the computation process of the linear interior point algorithm for improving the robust behavior of the numerical problem of the augmented parameter estimation. The test results show that the method has good application prospects.