Harmonic Space-State Based Analytical Modeling of Modular Multilevel Converters for Fast Simulation

Traditional detailed modeling modular multilevel converter (MMC) methods have been difficult to adapt to the computational efficiency challenges brought by the increasing number of MMC submodules and the expansion of simulation scale, and there is an urgent requirement for developing an MMC model with large time step. This paper derives a local analytical expression of MMC in frequency domain using harmonic space-state (HSS) method, and develops an analytical simulation method, which is capable of capturing the dynamic behavior of MMC during normal operation and fault condition while keeping high efficiency. Comparison against a detailed switching model (DSM) implemented in PSCAD validated the analytical expression and the proposed simulation method.