Study Of The Measurement Methods Of The Parameters Of Single-circuit And Incomplete Coupling Double-circuit Transmission Lines

The transmission lines are the kernel components in power systems and their power frequency electrical parameters are the basic data for the analysis and calculation of various power system problems.It is of great significance for the safety and stability of power systems to accurately measure the power frequency electrical parameters of the transmission lines.In this paper,the measurement methods of the transmission line parameters which are frequently used are analyzed.The advantages and disadvantages of these methods and their application are pointed out.In the study of the parameter measurement methods for single-circuit and incomplete coupling double-circuit transmission lines,the transmission lines are divided into symmetrical lines and asymmetrical lines based on the fact that if the lines are transposed or not.And they can also be divided into short lines and long lines according to the distance of the lines.Due to the regulation that un-transposed lines are all short lines,lumped parameter model is used to study the parameter measurement methods of these lines in this paper.Firstly,the situation of no interference lines around the measured lines is analyzed and the single circuit lines measurement model is built with non-power frequency method.On this basis,the incomplete coupling double-circuit transmission lines model is analyzed with non-power frequency method of no interference lines nearby.The measured lines are divided into two parts,the single-circuit part and the double-circuit part.The model of double-circuit part is primarily studied in this case.What's more,a new non-power frequency method is studied on condition that there are interference lines around the measured lines.All the coupled lines are comprehensively analyzed.The over-determined equations are built by the method of multiple independent measurements on all the above lines,and solved by the least-square method.The completely transposed lines are used for long distance transmission lines.Therefore,the symmetrical distribution parameter model is used in the study of these lines.Firstly,the distribution parameters measurement method of single conductor is analyzed by the homogeneous transmission line theory.The distributed impedance and distributed admittance are solved with transmission coefficient and wave impedance.Furthermore,the distributed parameter model of single circuit is studied.The solution of positive sequence and zero sequence parameters is derived.In addition,the distributed parameter model of the incomplete coupling double-circuit transmission lines is studied.The measured lines are divided into the single-circuit part and the double-circuit part.And the distributed parameters can be solved when the voltages and currents at two ends of the lines are measuredIn this paper,the lumped parameter models and the distributed parameter models are simulated by PSCAD.The measurement errors of different models are analyzed.The measurement system of the transmission line parameters based on GPS technology is introduced and the line parameters are simulated and measured with RTDS.