A Multi-rate Co-simulation of Combined Phasor-Domain and Time-Domain Models for Large-scale Wind Farms

Summary form only given. In the year 2015-2018, there are many sub- and super-synchronous interaction (S2SI) events, happened in China. However, traditional transient stability models, electromagnetic transient (EMT) models and hybrid TS and EMT simulation methods fail to capture the desired wide frequency band interactions between large-scale AC grids and wind farms. To accurately and efficiently capture wide frequency band interactions between AC grids and wind farms, a simulation method which can extend the time-step to 500ms and further adopt the multi-rate structure is highly required. For this objective, we propose a multi-rate co-simulation method, in which the target system is partitioned into electromagnetic transient (EMT) and shifted frequency phasor (SFP) subsystems, represented by our proposed transformation based SFP models and the traditional EMT models, respectively. The simulation efficiency of simulating large-scale AC grids is significantly improved by adopting a much larger time-step. Further, the multi-rate multi-domain transmission-line model (MDTLM) and the multi-rate frequency dependent MD-TLM are respectively proposed to reflect wideband interactions between AC grids and wind farms. Eventually, the multi-rate co-simulation is implemented based on the efficient SFP models, network partitioning, and so-called the multi-rate (FD)-MD-TLM. The performance (efficiency and accuracy) of the proposed method has been fully validated on a practical system integrating large AC grids and wind farms.