CONTROL METHOD FOR DIRECT CURRENT TRANSMISSION BY MEANS OF SEVERAL POWER CONVERTERS

摘要

The invention relates to a method for controlling at least three power converters (2), which can be controlled by a rectifier (6) or an inverter (8) and are connected together by a direct current network (7), in the region of power distribution and power transmission. The aim of the invention is to provide a method which has a simple structure and also works in a reliable manner. As a result, a measuring direct current voltage (Udc_l, ... Udc_rr; Udc_il ... Udc_ii) and a measuring direct current (Idc__rl, ... Idc_rr; Idc__il, ... Idc_ii) are measured on each power converter and respectively, transmitted to the respective rectifier control (11) and/or inverter control (12), and a rectifier desired direct power and/or inverter desired direct power (Pdco_rl, ... Pdco-rr,- Pdco_il, ... Pdco_ii) is determined for each power converter. The total of all desired direct powers (Pdco_rl, ... Pdco_rr; Pdco-il, ... Pdco_ii) is equal to zero, and a desired direct voltage (üdco_rl, ... Udco_rr; Udco__il, ... Udco_ii) is determined from each desired direct power, the smallest inverter desired direct voltage (Udco_il, ... Udco_ii) of all connected inverters (8) is fixed as minimal direct voltage (Udco) by means of a minimal direct voltage and the desired direct voltage, a desired direct current (Idco_rl; ... Idco_rr; Idco_il, ... Idco_ii) is formed from the minimal voltage (Udco) and the measuring direct voltage, a differential direct voltage (du_rl, ... du_rr, du_il, ... du_ii) is formed from the minimal voltage (Udco) and the differential direct current (di_rl; ... di_rr; di_il, ... di_ii) is formed from the desired direct current and the measuring direct current. The respective rectifier control (11) of the rectifier (7) is controlled in such a manner that the total of the differential direct voltage (du_rl; . du_rr,- du_il, ... du_ii) and the differential direct current (di_rl, ... di_rr; di_il, ... di_ii) is minimal, and the inverter control (12) of the inverter (8) is controlled in such a way that the difference between the differential direct current and the differential direct voltage is minimal.