摘要：AbstractA coordinate control strategy is proposed to secure fault-ride through (FRT) for voltage source converter (VSC) based multi-terminal high voltage dc transmissions (MTDC) integrating the offshore wind farms (OWFs). The short circuit fault in the ac grid obviously reduces the voltage at the connection point which, in turn, block the power output of MTDC systems instantaneously. The resulting power imbalance in MTDC system correspondingly charge the DC capacitors. In the absence of suitable countermeasures, this would lead to increased dc voltage, which would further lead to potential equipment damage in the installation. Therefore, for the OWF-integrated MTDC systems, keep ing the dc voltage within a reasonable value is the key to achieving the fault-ride through. The grid side converters (GSCs), wind farm side converters (WFCs), and doubly fed induction generators (DFIGs) will operate under the fault operation mode when there is a three-phase symmetrical fault. An improved reactive power compensation method is applied to GSCs’ controllers to enhance the stability of the ac grid. The controllers of WFCs reduce the ac voltage amplitude of OWFs according to the dc voltage signal, which correspondingly decreases the power transmitted to the MTDC system. As a result, the increase in dc voltage is restrained. Since the degree of voltage decline for WFCs is limited by the over-current capability of the power electronics, an active power reduction control of DFIG is used to complement with this method. Different simulation scenarios are presented by DIgSILENT PowerFactory to verify the effectiveness of the proposed control strategy.
关键词：KeywordsMulti-terminal High Voltage DC Transmission (MTDC)Offshore Wind Farms (OFWs)Doubly Fed Induction Generator (DFIG)Fault-ride Through (FRT)Voltage Source Converter (VSC)
