| 摘要 |
This application relates to methods and apparatus for testing the connection integrity of a plurality of series connected cells/sub-modules (103) of a voltage source converter (100), such as a valve (101 a,b) of a multi-module converter (MMC). Each cell comprises an energy storage element, for example a capacitor (105), and a plurality of switch elements (106), e.g. connected in a half-bridge arrangement. Each switch element has an associated freewheeling diode (107). The method comprises applying an electrical test stimulus (V STIM+ , V STIM- ) to the plurality of series connected cells, wherein the electrical test stimulus has a voltage that is lower than the rated operating voltage of the voltage source converter, but which is greater than a threshold voltage, which is sufficient to forward bias freewheeling diodes of each of the first plurality of sub-modules to provide a conduction path through the plurality of series connectedcells/ sub-modules. The electrical characteristics of the plurality of series connected cells to the electrical test stimulus is monitored and used to determined whether the cell/sub-moduless are connected correctly, for example by comparing to an expected characteristic. |
