The invention relates to a method for controlling current/power flow within a power transmission system, comprising two or more interconnected converter stations. The method comprises the steps of: providing a DC admittance matrix given from the DC grid; providing a current distribution matrix for a number of, such as for all possible AC/DC converter outages; providing a DC bus voltage vector for the DC grid; the DC bus voltage vector being a vector containing the values of the voltage change at the AC/DC converters, measured at the AC/DC converters, before, during and after a forced current change occurs at one of the AC/DC converters; establishing a generalized droop feedback gain matrix G; controlling current/power flow within DC grid towards predefined setpoints, by use of control law. The invention presents an analytical approach to derive the generalized feedback gain allowing to differentiate the system response, i.e. current sharing, e.g. for different converter outages. The control approach aims at improving the DC voltage droop control by combining the local voltage signal available at the converter terminals, with remote voltage signals at different locations in the DC system, by means of communication. The local voltage feedback control is used for a fast, reliable system response. The invention also relates to a control device, implementing the method in the power transmission system.
|IPC||H02J 3/ 36 A I|
|Country||International Bureau of the World Intellectual Property Organization (WIPO)|
|Publication status||Published - 11 May 2017|