INVESTIGATION OF ASYMMETRICAL MODES OF THREE-PHASE THREE–LEG TRANSFORMER WITH WINDINGS CONNECTION IN ZIGZAG

Abstract

The optimal configuration of phases placement of double circuit compact controlled self-compensated high-voltage power lines (KUSVL ) with the voltage of 330-500 kV at the condition of achieving of the maximum admissible value of the electric field tension on the surface of split phase at a given design was determined. The parameters of these lines at the extreme values of the angular shift (θ) between the circuits’ systems voltages were calculated. It was shown, that the surge impedance of KUSVL without special phase-shifting transformers (e.g. θ = 0˚) is minimal, and is equal (for each phase) for the option of 330 kV and wires 3AS-300/39 - 196 ohms, and for voltage of 500 kV and phase conductors 6AS-240/39 –162 ohms. The magnitude of transmission capacity of considered line (for both circuits) at rated voltage is maximal and equal to 1118 MW (for 330 kV line) and 3080 MW (for 500 kV line). At changing of line to the mode of angle θ = 180˚ (with special phase-shifting transformer) surge impedance is maximal and the transmission capacity minimal. Ratio of the maximal value of transmission capacity to the minimal (regulation range) reaches values of up to 1.5.

Keywords

• simulation