Anomaly Correction Methods Of Voltage Phase Angle Difference At Both Ends Of Transmission Line In Power System And Their Application

One of the important advantages of synchronized phasor measurement units(PMUs)is to provide synchronized phase angle measurements.However,due to various factors,especially the time synchronization problem,some measured phase angle difference(PAD)data between PMUs is abnormal.At the same time,PMUs rely on unencrypted,predictable civilian satellite signals as the time source and is vulnerable to satellite time synchronization attacks(TSAs),resulting in errors in PMU time and phase angle measurements.Aiming at the problem of abnormal data of PMU phase angle difference,the characteristics of measured PAD,abnormal detection,correction methods and their application in TSAs location are studied in this dissertation,which can improve the quality of PMU data and ensure the application effect of PMU.The main research work and novel achievements are as follows:Combined with the analysis for the characteristics of abnormal PMU voltage PAD between both ends of the transmission line and abnormal classification,preliminary detection and type classification methods of the PMU voltage PAD between both ends of the line are proposed.Based on the approximate linear relationship between the voltage PAD between both ends of the line and the active power,a preliminary detection method of abnormal PAD data is given;combined with the analysis of the measured PMU PAD data at both ends of the line,the abnormal types of the measured PMU PAD data at both ends of the line are summarized,and the corresponding cases are given.An abnormal type classification method based on hypothesis testing is proposed,which can classify constant and time-varying deviations and provide a basis for abnormal data correction.Combined with characteristic that the line reactance is constant,detection methods for voltage PAD at both ends of the line based on historical statistics and abrupt change index are proposed,which can detect satellite TSAs.Through the sensitivity analysis of line parameter identification,the reactance is selected as the online monitoring parameter for abnormal detection;two detection indexes and adaptive thresholds are constructed based on the statistics of the estimated reactance;the sliding time window is used to monitor the estimated reactance change caused by the PAD deviation,taking the line as the object for detection.The tests with simulated and measured data show that the method has strong detection ability,and the detection threshold can be automatically determined according to line parameters and measurement noise level without manual adjustment.A data correction method for constant PAD deviation at both ends of the line without the need of line parameters is proposed.Based on the characteristic that the line impedance is unchanged during short period,the line impedance is estimated using the PMU data under two working conditions;then,a constant PAD deviation estimation model without known line parameters is given by eliminating the line parameters;Through the golden section algorithm,the constant PAD deviation estimation and correction are finally realized.The tests of simulated and measured data show that the method can accurately estimate the deviation,has strong engineering practicability,and line parameter identification results are greatly improved after data correction.A data correction method for time-varying PAD deviation at both ends of the line based on line reactive power loss is proposed.Based on the measured and estimated value of line reactive power loss,a single-time PAD deviation estimation model is constructed;based on the relationship between the voltage PAD and the line parameter,the time-varying deviation estimation model by single-snapshot data is converted into a constant line parameter estimation model by multi-snapshots data,which improves the model’s robustness to noise;after obtaining the line parameters,the PAD deviation can be reversed,and the correction of time-varying deviation using the data of a single working condition is realized.The tests of simulated and measured data show that the method is suitable for the correction of different types of time-varying deviation and has strong robustness to noise.Using PAD detection and correction information,combined with the construction of the equivalent diagram and the search and aggregation of synchronized nodes under satellite TSAs,a satellite TSAs location method for power system is proposed.Combined with the characteristics of TSAs,a method of constructing the system equivalent graph and its adjacency matrix for attack searching is proposed;based on the detection information at both ends of the line,a search and aggregation method for the internal synchronization subsystems formed by the division of the alarm line is given;according to the different connection situations of the subsystems,the corresponding attack location measures are respectively proposed based on the deviation correction results and the assumption that there are more normal nodes than attacked nodes.The tests with IEEE 39-bus system and the actual system of a province in our country show the effectiveness and practicability of the method.