Series Compensation To The Development Of The Spark Gap Test Current Source

Taking the general range of the secondary output current of CT for SC(Series Compensation) equipments as a reference, the research subject of developing a kind of AC current source with higher power is set down as it is urgently required in the manufacturing, installing, and debugging of the control system of Triggered Spark Gap. Although the initial purpose of the task is to offer a technical solution for the testing of control system of Triggered Spark Gap in off-line conditions similar to the one in operation on-line, the researching of this task is of broadly significance, because this device can be used in all the off-line testing of the electrical equipments powered by CT.This dissertation firstly makes a review of the PWM(Pulse Width Modulation) control technique, and a general introduction of the evolution of IGBT in the recent years. Then it confirms the method of inverting DC current to AC current with VSC(Voltage Source Converter), and modulating in hysteresis current control technique, so that the output current is independent of the load in some extent. After that, the circuit designed is simulated in the PSpice environment, and finally get the elementary circuit. Tested and debugged in the laboratory for many times, the sample device finally works successfully, the performance of which caters to anticipation, by being applied effectively in the process of installation and debugging of the control system of Triggered Spark Gap in the "SanBao" series compensation station in XuZhou, Jiangsu Province.Hysteresis current control and drive of IGBT are key sections of the study, and their performances will directly decide the efficiency of tracing the standard waveform. As for that, the better hysteresis current control circuit is identified after the comparison of two alternatives. Regarding the drive of IGBT, the study designs a particular delay circuit for the IGBT inverter bridge, as well as making a protection from the overcurrent, desaturation and undervoltage with existing chips.In addition, this study makes a mathematic analysis on the ability of carrying R-L loads of the device, and concludes a method of calculating maximum load, which is validated by simulating.