The Research On Physical Simulation And Main Protection With Reclosure Of Double Transimission Lines On The Same Tower

With the constant development of the national economy, our country's electric power demand has been growing day by day. Following the first 500kV double transmission lines on the same tower hong-long lines to be in use, the double transmission lines on the same tower has been widely used because of its advantages in transmission capacity and saving transmission corridor. Due to its complex mutual inductance and various fault kinds, double transmission lines on the same tower can't adopt the main protection and automatic reclosing used on single circuit transmission lines. The physical model of double transmission lines on the same tower being used only considered the zero-sequence mutual inductance, which can't simulate the difference in double transmission lines on the same tower's mutual inductance, so that it also can't actual reflect the characteristics of electrical quantities under different kinds of faults. Therefore, the research for double transmission lines on the same tower is very important and necessary. The work is very valuable in theory and application to solve the problems in double transmission lines on the same tower such as transmission lines'symmetry, physical model, capacitance current compensation and adapt reclosure.For double transmission lines on the same tower , the different phase sequence arrangement mode will affect the transmission lines'symmetry. In this paper, several existing different phase sequence arrangement modes'effects on the symmetry of double transmission lines on the same tower were deeply analyzed. Some suggestions on the phase sequence arrangement and transposition form to ensure the double transmission lines on the same tower's symmetry were also proposed.To solve the problem that the existing double transmission lines on the same tower's physical model can't simulate the difference in mutual inductance, this paper presented a new method for designing the physical model. The new physical model designed by the new method can really simulate the difference between the mutual inductances. An actual segment of double transmission lines on the same tower was taken as prototype , and the physical model was constructed using the new method. Moreover, the physical model's simulation capacity under various normal and fault conditions was confirmed through dynamic simulation test and digital simulation test.According to the service experience and the massive simulation results, the capacitance of double transmission lines on the same tower was influenced by the operational model and the surroundings. As phase segregated 8 protection was used as the main protection for double transmission lines on the same tower, the general capacitance current compensation can't meet the actual operational requirements. A new scheme for capacitance current compensation was proposed in the paper basing on the comparatively analysis of the steady compensation and the transient compensation. The new capacitance current compensation method can get over the effects of the operational model and surroundings, and compensate the capacitance current exactly, thereby reduce the threshold of the protection and improve its sensitivity.At present, the researches on adapt reclosure are mainly focused on the single phase fault on the single transmission line, very few researches are specially aimed at the double transmission lines on the same tower. This paper deeply analyzed the voltage adapt reclosure and the phase adapt reclosure, and then presented a new adapt reclosure basing on the characteristics of single phase fault and single phase cross single phase fault in double transmission lines on the same tower . Digital simulation indicated that the new adapt reclosure can judge the fault properties of single phase fault and single phase cross single phase fault in double transmission lines on the same tower exactly.