Control method for direct-current by means of a plurality of converters

Abstract

At least three power converters in a power distribution and power transmission system can be controlled as rectifiers or inverters and are connected together by a direct current network. A measuring direct current voltage and a measuring direct current are measured on each power converter and respectively, transmitted to the respective rectifier control and/or inverter control, and a rectifier desired direct power and/or inverter desired direct power is determined for each power converter. The total of all desired direct powers is equal to zero, and a desired direct voltage is determined from each desired direct power, the smallest inverter desired direct voltage of all connected inverters is fixed as minimal direct voltage by means of a minimal direct voltage and the desired direct voltage, a desired direct current is formed from the minimal voltage and the measuring direct voltage, a differential direct voltage is formed from the minimal voltage and the differential direct current is formed from the desired direct current and the measuring direct current. The respective rectifier control of the rectifier is controlled to minimize the total of the differential direct voltage and the differential direct current, and the inverter control of the inverter is controlled to minimize the difference between the differential direct current and the differential direct voltage.