Study On Fault Phase Selection Method Of Double-Circuit Lines On The Same Tower

The double-circuit transmission line of the same tower has been widely used in power transmission system because of its advantages of large transmission capacity,less land occupation,strong transmission capacity and high reliability of power supply,but the coupling between the double-circuit lines of the same tower is complicated,not only between the single circuit lines,but also among the two circuits,and the traditional phase selection element can not achieve the ideal effect when it is directly applied to the double circuit line of the same tower,so it is necessary to study a new method suitable for the phase selection of the double circuit line of the same tower.Therefore,a new method of fault phase selection based on wavelet transform is proposed in this paper.The method proposed in this paper takes the fault characteristic analysis of double-circuit line of the same tower as the research object,mainly from two aspects of fault phase selection and fault line selection based on current modulus.It is of great significance to improve the sensitivity and accuracy of double-circuit line fault protection and to ensure the safe and stable operation of power network.On the basis of analyzing the structural characteristics of double circuit lines of the same tower and the arrangement of conductors,the decoupling method based on ordered component and the decoupling method based on module component are introduced.By analyzing the multi-resolution of wavelet transform,the feasibility of discrete wavelet transform of modulus component based on db4 mother wavelet is discussed.With the help of pscad/emtdc simulation software,a double-circuit simulation platform for the same tower was built,and the equivalent system and the line model of the double circuit line of the same tower were perfected.By analyzing the fault simulation results of double-circuit line in the same tower,the effects of different fault types,fault location and transition resistance on the characteristics of current signal are studied.A scheme of fault line selection and phase selection based on wavelet transform for double-circuit line of the same tower is proposed.The fault line is identified accurately by correlation coefficient analysis,and the fault phase is identified byanalyzing the high frequency wavelet coefficients of Level-1 layer.The effectiveness and reliability of the line selection and phase selection scheme are verified by a large number of simulations of different fault types,fault locations and transition resistors.