Abstract:

An AC/DC power system with three DC links is presented for the investigation of DC damping control.The presented system is of complicated grid structure and multiple oscillatory modes,which extensively exist in practical AC/DC power systems and must be given enough consideration in DC damping controller design. By means of the modal analysis and the transient simulation.the performances of the system are then analyzed.Moreo-ver,multiple DC damping controllers are designed based on the proposed power transmission system.The analysis of root lOCUS shows that the frequency differences across DC links are superior to the active power deviations on AC tie lines in the phase compensation design,so that they can be selected as the input signals into DC damping con-trollers.Furtherm ore,the results of transient simulation demonstrate that the designed DC damping controllers effectively improve the damping of the power transmission system.

Key words: power system, modal analysis, transient simulation, DC damping control