Study On Dynamic Physical Model Of Double-circuit Transmission Lines On Same Tower Based On The Analysis Of Space Magnetic Field

With the development of economy in our country, more and more requirement for electrical power suply and transmission capacity is demanded in recent years. By the advantage of tranmission capacity and efficiency, and the rate of return on investment, it is rapidly developed and widely applicated that the technology of double-circuit transmission lines on same tower. But with the complicated fault type and transient characteristics of the double-circuit transmission lines on same tower, it is no longer suitted for the thnology that the common failure analysis principle and protection configuration of relay used on single-circuit transmission lines. Specific research on devices of relay protection and control must be carried on.It depends on the theory research and experiment result that the performance analysis and evaluation on the relay proctection and control devices, and also needs for the dynamic simulation test on physics model which can truely reflect the physical properties of double-circuit transmission lines on same tower. But the present model can not reflect the circuit parameters characteristics well. So it is presents in this paper that the physical model of double-circuit transmission lines on same tower based on theory of space magnetically coupling. This model can fully response the mutual inductance parameters between phases of double-circuit, and response accurately the electric parameters change characteristics while falure occurs on the double-circuit transmission lines on same tower.First it is analysied and described that the present situation of research and application of double-circuit transmission lines on same tower, analysied the basic principal and main problem of previous physical models of double-circuit transmission lines on same tower. It is described that the characteristics and necessity of the study on double-circuit transmission lines on same tower based on space magnetical theory.According to the circuit characteristics of some kinks of double-circuit transmission lines, it is analized for the theory basis and reference data of the measurement and simulation of circuit characteristics that calculation method on each sequence impedance of double-circuit transmission lines. With the tool of PSCAD/EMTDC, it is achieved by the digital simulation mode of double-circuit transmission lines on same tower with the datas of common tower model commonly used in practical projects, that the steady state digital simulation parameters of double-circuit transmission lines on same tower.The design philosophy of the model is the same with the production principle of self-inductor and mutual-inductor of real transmission line which created by the space magnetically coupling of circuits. It is designed with three segmentation transposition structure, first builds single block model of the magnetic flux loop with multiple coil and iron core, then builds segmented model by connecting the wires and testing and adjusting the parameters. At last builds the full physical model of double-circuit transmission lines on same tower based on theory of space magnetically by conversion series connecting the three subsection. It is detialed descriped that the construction process of physical model. It is built that the physical model of double-circuit transmission lines on same tower by means of adjusting the model papameter with the spatial position of model coil which is descieded by the digital simulating of the circuit parameter.By the comparision of the real line parameters, digital simulation parameters and the sequence parameter of double-circuit transmission lines on same tower based on space magnetical theory, it shows rhat the sequence parameter of physical model can more accuratlly response and simulate the real parameter and character of double-circuit transmission lines on same tower.Finally it is introduced that the dynamic simulation test with this model, and it is also proved that the correctness and practicability of this model by digital simulation of failure experiment. It provides fine experimental plat for the research of dynamic simulation test on double-circuit transmission lines on same tower and the development and testing for relay protection devices.