Study On Induced Voltage And Current Of 500KV Parallel Transmission Line And Its Resonance Problem

Parallel transmission line can increase the unit's land power transmission capacity and it will be the main construction form of transmission line. As its two major problems in actual operation, induced voltage, current and its open-phase resonance will have great impact on transmission line's planning and design, relay protection and the arrangement of operation mode.In this paper,all the research are closely related to the actual operation and typical designing of the parallel transmission line through theoretical analysis and simulation, several influencing factors on these two issues have been deeply analyzed. The main contents and innovations include the following:Firstly,on the basis of the summary of the main 500kV towers, the parallel lines's original parameters ,the original order parameters and simplified order parameters for different computing needs have been detailed calculated. The influencing factors of the order parameters have been analyzed. The theoretical line parameters, external network equivalence and the entrance impedance model have been derived.Secondly,on the basis of the mathematical model of the shunt reactors, the compensation principle on the condition of normal operation and no-load operation is analyzed. The mathematical models and the function of the neutral reactors on shunt compensated lines were analyzed. The solution of the neutral reactors'phase-to-phase full compensation capacitor of different towers were calculated.Thirdly, on the basis of the opening and closing of transmission line grounding switch's operating conditions corresponding to the induced voltage and current, the approximate numerical solution of the parallel line's induced voltage and current have been calculated. The related factors have been analyzed. Linked to the specific lines, some suggestions of the general selection of 500kV line's earthing switch have been put forward. Fourthly, the principle of the open-phase resonance and the adjacent line resonance and resonance-inhibiting mathematical model of the neutral reactor have been analyzed. The numerical solution of the neutral reactor corresponding to typical line in order to avoid the resonance have been calculated. Through theoretical analysis and the specific line simulation, several influencing factors of the open-phase operation resonance have been analyzed. The measures to suppress the resonance have been put forward.