| Abstract |
The transport of electric power is constantly increasing in importance and this is accompanied by a corresponding increase in the importance of interconnections between differing grids, e.g. between the West European UCPTE Grid and neighbouring networks. In the case of two networks which are asynchronous, with slightly differing frequencies and the resulting phase shift, direct power exchange via an AC-link is not possible. HVDC (High-Voltage Direct Current) transmission is the only possibility for power interchange between two such networks. Digital systems (microcomputers) are used for the open-loop, closed-loop and protection systems of the HVDC link. This paper describes the digital closed-loop controls. A standard multiprocessor system which has proven itself in the field of drive controls is used. The closed-loop control has been designed as a two-channel redundant configuration to improve the availability and reliability of the HVDC link. While one channel actively controls the HVDC link, the second channel operates in hot-standby mode and can take over control at any time. Proper functioning of the closed-loop control system was proven by tests in a network analyser. |
