Simplified Modeling Method for Full-power Converters Under Positive and Negative Sequence Separation Control

Current gird codes require that renewable plants absorb negative-sequence inductive reactive current to suppress the rise of negative-sequence voltage. However, it increases the complexity of simulation model since full-power converter is required to have the ability to control both positive and negative sequence components, which brings great challenges for the simulation efficiency of large-scale converter-based system. To address the problem, this paper proposed a novel simplified modeling method for full-power converters considering relay protection requirement. Due to the isolation of the DC link, the fault characteristics mainly depend on the control strategy of grid-side converter. Hence the simplified model focuses on the representation of the grid-side converter. Neglecting the complex switching process of power electronic devices, this paper retains converter's function and represent it with mathematical differential equations based on the conservation of power and control strategies. The simulation results shows that the simplified method can improve the simulation speed while ensuring the simulation accuracy. The proposed method can be used for modeling the power system with large-scale renewable energy sources to achieve fast simulation, which provides the support for relay protection analysis.