Method and apparatus for eliminating overmodulation in a power plant

摘要

A method and apparatus for eliminating overmodulation in a power plant is provided. The power plant has a direct voltage network connected to at least one alternating voltage network through a station. The station is adapted to transmit power between the direct voltage network and the alternating voltage network and includes at least one converter. The converter is adapted to convert direct voltage into alternating voltage and convert alternating voltage into direct voltage. The method comprises the steps of calculating a reference alternating voltage and measuring a direct voltage between two poles of a direct voltage side of the station. The reference voltage is divided by half of the direct voltage and this quotient is compared with a predetermined value. When the quotient exceeds the predetermined value, a first signal is sent to a means for controlling the converter. In response to receiving the first signal, the converter is controlled to increase consumption of reactive power on the alternating voltage side of the station.