Considerations on the coordinated control of controllable reactors

In the extra-high voltage long transmission line, the non-allowed increasing of power voltage and the corresponding transient oscillation over-voltage are often occurred. The continued burning of the secondary arc usually keeps quite a long time for the high voltage level, long line and large capacity. There must lead to the failure of the re-closing if the secondary arc is not extinguished promptly, which will affect the security and stability of the system. In this paper, the dynamic induced over-voltage model as well as the dynamic secondary arc model in single-phase asymmetric breaking is established based on the distribution parameters of EHV long-line. A novel kind of high-controlled shunt reactor with a small reactor in the neutral is adopted to suppress the transient oscillation over-voltage and the secondary arc. Since the neutral point small reactor is constrained by the positive-sequence and zero-sequence capacitance of the line and the shunt reactor as well. The coordinate control of the neutral controllable small reactor achieves the dynamic change in accordance with the high-controlled shunt reactor which can realize the compensation of the phase capacitor so as to suppress the induced over-voltage and the secondary arc effectively.