Detection And Correction Method Of Field PMU Phase Angle Measurements Deviation At Both Ends Of Transmission Line

Remote synchronous phase angle measurement is one of the important characteristics of phasor measurement unit(PMU).However,due to the fault of power transformer components,the aging of data acquisition system equipment and the time asynchronous attack of GPS,the PMU measurement phase angle data at each end of some field transmission lines will be abnormal,resulting in abnormal line power measurement,which will affect the subsequent advanced application based on PMU devices.Aiming at the synchronization problem of PMU phase angle measurement at the regional level of transmission lines,this paper studies the detection and correction method of asynchronous deviation(power factor angle deviation,PFAD)of local terminal voltage and current phase angle measurement,and gives the phase angle synchronization correction scheme of transmission lines under unknown parameters.The main work and innovations of this paper are as follows:(1)A power factor angle deviation caused by transmission line power anomaly detection method is proposed.Specifically,combined with the influence characteristics of power factor angle deviation,the mechanism of abnormal reactive power measurement of PMU data in double-circuit line is explained.Furthermore,based on the derivation of the line power loss expression without phase angle,combined with the error propagation law,the threshold determination method of line power deviation is given,and then a power measurement anomaly detection method of transmission line is proposed,which can be used to detect the power factor angle deviation.This method does not require pre-calibration or high-precision power transformers,can realize online detection of abnormal power measurement,and is suitable for PMU and SCADA data.(2)A power factor angle deviation correction method based on PMU measurement data is proposed for the asynchronous deviation of local voltage and current of singlecircuit line.Using the PMU measurement data under two working conditions,based on the short-term invariance of the transmission line and the approximately equal transmission power of the double-circuit line,an estimation model of the power factor angle deviation relationship at both ends of the transmission line is established.On this basis,combined with the reactive power check of transmission lines,the estimation and correction of power factor angle deviation are finally realized.Simulation and actual measurement examples show that the method can accurately estimate the local terminal voltage and current asynchrony deviation of single-circuit lines,and has strong anti-noise performance and engineering applicability.(3)Aiming at the abnormal phenomenon of reactive power measurement caused by power factor angle deviation in some field lines,a ’three-step’ power factor angle deviation correction method for double-circuit lines is proposed.Combined with the operating characteristics of approximately equal transmission power of symmetrical double-circuit lines and the short-term invariance of line parameters,a mathematical model of the relationship between power factor angle deviations at each end of doublecircuit lines is established.Based on the estimation of reactive power loss and line parameters that do not involve phase angles,the correction of power factor angle deviations of double-circuit lines is realized.Compared with the single-circuit power factor angle deviation correction method,this method does not require line parameters,and the parameter identification accuracy is improved after the method corrects the double-circuit power factor angle deviation.Simulation examples verify the effectiveness and robustness of the proposed method.The actual calculation example shows that the proposed method can correct the problem of transmission line synchronization and abnormal reactive power loss,and then correct the reactive power of the line.At the same time,the corrected PMU measurement of the transmission line can pass the midpoint voltage amplitude test,which verifies the engineering applicability of the proposed method.(4)Considering the most common situation that the PMU phase angle measurement at each end of the transmission line has deviation,a synchronous correction method for PMU phase angle measurement of transmission line under unknown parameters is proposed.Combined with the π-type equivalent model of the transmission line,a modified model considering the synchronization problem and the asynchronous PMU phase angle measurement at the local end is established.Based on the short-term invariance of line parameters,a difference estimation method for different ends of the same measurement of transmission lines is proposed.Combined with line reactive power verification and parameter estimation,a synchronous correction scheme for line PMU phase angle measurement is proposed.Simulation and actual calculation examples show that the method can effectively correct the PMU phase angle measurement asynchrony problem of transmission lines,and has strong engineering applicability.At the same time,the corrected measurement data can pass the midpoint voltage test,and the line parameter identification results are greatly improved.