Generic averaged value models for two-level voltage source converter (VSC) and modular multilevel converter (MMC) are proposed. A brief summary of the operating principles of two-level VSC and MMC is given first

followed by theoretical derivation of averaged value models for two-level VSC and MMC. By analyzing the DC fault response of two-level VSC and MMC

a unified modeling method that is able to simulate DC fault response for two-level VSC and MMC is proposed. Detailed switching models and the proposed averaged models of two-level VSC and MMC are built in PSCAD/EMTDC. Responses of detailed models and averaged models during steady-state operation

DC fault and AC fault are compared and verified. The results show that the averaged models are able to generate identical fundamental results as the detailed switching models while significantly improving simulation speed. The proposed averaged models are suitable for fast simulating the electro-magnetic transients of large grids incorporating numerous VSCs and MMCs. This work is supported by National Natural Science Foundation of China (No. 51377067

No. 51261130484) and State Grid Corporation of China Under the Contract State Grid Research (No. 2013-304).