An Intelligent Adaptive Reclosure Scheme for High Voltage Transmission Lines

A criterion using residual voltage and fuzzy decision to improve the successful rate of reclosing is proposed. Residual voltage of the faulted phase still remains after a single phase to ground fault occurs followed by the faulted phase breaking because distributed parameters of the high-voltage transmission line and coupling capacitance between one phase and another phase transmission lines exist. Therefore, the residual voltage can be used to distinguish between permanent faults and transient faults of transmission lines. However, a permanent fault may be regarded as transient one when permanent single-phase fault to ground occurs near either end of the transmission line according to the existing residual voltage scheme. In this case the system stability will be threaten. In order to overcome this problem, a new scheme using fuzzy decision is proposed in this paper, the information of capacitance coupling voltage and the boundary condition will be used to revise the present criteria, so that the correct rate of judgment can be improved extremely. A classical model with two inputs and one output is used to design the fuzzy controller, a STD industrial control computer system is used as the hardware platform. The analysis and test results show that the new criterion can be widely applied in protective relaying with reclosing, especially digital relaying of power systems.