Investigations On Controlled Switching Of EHV Series Compensated Line

State Grid Corporation of China is toward the direction of the development of large-capacity and long-distance. On more than500kV line, we can make use of series capacitor compensation technology to compensate part of the inductance. Which is not only equivalent to shorten the electric distance communication lines, but also reduces the line transmission loss. Improving the stability limit of the lines has played a vital role. However, the installation of series compensation device will destroy the line’s impedance. When the line for normal closing or single-phase fault need reclosing occurs, it will produce electromagnetic phenomena associated with series compensation devices on the line. These phenomena caused by problems in the development of EHV lines need to be solved.Firstly, the article introduces the series compensation device, including its working principle, function and application. Then analyzed the lines with series compensation device in normal closing and single-phase fault need reclosing occurs the produce principle of overvoltage and inrush current. Establish the relevant line model in ATP-EMTP software, and simulate the situation of the normal closing and single-phase fault reclosing. The results show that the random time closed circuit breaker will produce very big overvoltage and inrush current. And the waveform of voltage and current is irregular when the switch is closed or opened. Then this paper gives some methods of inhibiting overvoltage. Among them, the controlled switching technology is put forward to becoming the new path to solve the problem of overvoltage and inrush current.This paper studies the line with series compensation device about the principle of overvoltage and inrush current. Using the controlled switching technology, By ATP-EMTP software to establish a simulation model of the normal closing, and the simulation model of single-phase fault reclosing. First it compares the different switching angles of overvoltage and inrush current in single-phase, and then chase down the best switching phase, applying to the three-phase lines. After the simulation of the switching strategy, the results show that the line with series compensation device using the synchronous switching strategies can effectively suppress the overvoltage and inrush current problems. Then establish a simulation model of the line without series compensation device, the results of the simulation were compared with the results of the line with series compensation device, which verify the role of series compensation device in the line. Finally this paper introduces the design of the phase selection control system. This system is based on DSP2812as the core, the system can real-time acquisition signals in the power grid. After FIR filtering process to extract the reference signal of zero, through the relevant driver module circuit breaker for related operation, achieve congenial to choose cutting. Finally the accuracy of the experimental test shows the system meets the requirement of accuracy. Which confirmed the practicability of the proposed controller.