Damping Torque Analysis of DC Voltage Stability of an MTDC Network for the Wind Power Delivery

Conventional damping torque analysis (DTA) is a well-known and widely used method to examine the low-frequency electromechanical oscillation stability of an AC power system. This article expands the conventional DTA for studying the DC voltage stability of an MTDC network. In the article, analysis is carried out to prove that the DTA can be applied to examine the DC voltage stability of MTDC network. Application of DTA can not only reveal the insight about why growing DC voltage oscillations may occur, but also to guide the parameters tuning of control systems of voltage source converters (VSCs). The parameters tuning is to avoid that the damping contributions from the VSCs in the MTDC network are very much varied such that DC voltage instability may occur after some of VSCs are withdrawn from operation. In addition, DTA can also be applied to guide the parameters setting of a current flow controller (CFC) in order to ensure the DC voltage stability of the MTDC network after the CFC is installed. An example MTDC network is used to demonstrate and evaluate the applications of DTA in the article.