POWER TRANSMISSION SYSTEM FOR IMPROVING TRANSMISSION CAPACITY OF URBAN POWER GRID THROUGH NON-SINE ALTERNATING CURRENT POWER TRANSMISSION

摘要

Provided is a power transmission system for improving the transmission capacity of an urban power grid through non-sine alternating current power transmission. The system comprises a first waveform conversion system and a third waveform conversion system both for converting a sine wave into an alternating square wave, and a second waveform conversion system and a fourth waveform conversion system both for converting the alternating square wave into the sine wave; the first waveform conversion system is connected with the second waveform conversion system through a first polar wire and a second polar wire, and the first polar wire is arranged parallelly to the second polar wire; the third waveform conversion system is connected with the fourth waveform conversion system through a third polar wire. Through the use of the capability of bidirectional current conduction of voltage source converters and with the help of switching devices, the power transmission system provided in the present invention well solves the problem as to capacity expansion of alternating current transmission lines without increasing the short-circuit current level of the power grid, and moreover, the power transmission system has transient functions, such as dynamic reactive power compensation, and consequently is of great importance to addressing the contradiction between the increasingly growing loads in large cities and the gradually rising difficulty in building new transmission lines.