1. School of Electrical Engineering Wuhan University Wuhan 430072 China; 2. Central China Division of the State Grid Corporation of China Wuhan 430077 China
Abstract：Wind or PV power interfaced with HVDC system is an ideal approach to transmit power for renewable energy consumption. It is worthy of further study the multi-band oscillation (MBO) of direct drive wind farm based on direct-drive permanent magnet synchronous generator (D-PMSG) interfaced with voltage source converter-based HVDC (VSC-HVDC) system. Firstly, the dynamic models of D-PMSG and VSC-HVDC are established respectively, and the interface dynamic equation between them is deduced, and then the complete model of system is obtained. Based on the eigenvalue analysis, it can be found that there exist low frequency oscillatory (LFO), sub/sup-sybchronous oscillatory (SubSO/SupSO) and high frequency oscillatory (HFO) modes, and these modes are not only related to the parameters of the converter controllers, but also to the short-circuit ratio (SCR) of VSC-HVDC receiving-side power grid, and the HVDC transmission line parameters. Time domain simulation by PSCAD/EMTDC verifies the correctness of the model and eigenvalue analysis results. Furthermore, the influence of SCR and HVDC transmission line parameter on the damping characteristics of MBO is further studied in detail. It is found that, it is especially necessary to monitor the operating state of receiving-side power grid whose SCR is too low, that may deteriorate the damping ratio. Considering the HVDC transmission line parameter has a great influence on HFO mode, HVDC transmission whose line length is too short shall be given attention.
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2018, Vol. 33 
