基于新型直流风电机组的串联型全直流发电系统设计研究

通过直流风电机组(DC wind turbine, DCWT)建设直流风电场实现风能的直流汇集与直流传输是海上风电系统的主要发展方向之一。为了使DCWT具备高压绝缘隔离、能量双向流动以及直流短路故障自清除能力，提出了一种适用于串联型全直流发电系统的新型DCWT拓扑。该DCWT拓扑采用了H桥结构的DC/DC变换器代替传统的隔离型DC/DC变换器，将DCWT直接串联并加以调制实现低压直流到高压直流的变换。基于PSCAD/EMTDC搭建了基于新型DCWT的串联型全直流发电系统仿真模型。经风电系统的DCWT在输出功率均衡、输出功率不均衡、高压直流母线电压波动等稳态运行工况以及故障DCWT动态切入切出等故障运行工况下的仿真，验证了该DCWT的输出特性、系统的运行特性以及系统对故障DCWT的处理能力，提高了直流风电场的运行可靠性与灵活性，为直流风电场的建设提供了一种切实可行的解决方案。

Design and research of a series all-DC power generation system based on a new DC wind turbine

It is one of the main development trends of offshore wind power system to develop a DC wind farm consisting of a DC wind turbine (DCWT) in order to realize DC collection and DC transmission in wind energy. In order to reach functions of DCWT in high-voltage insulation isolation, bidirectional energy flow and DC short-circuit fault self-cleaning, a new DCWT topology suitable for series-connected wind farms is proposed. Adopting a DC/DC converter with H-bridge structure in place of the traditional isolated DC/DC converter, DCWT directly connected in series and modulated can realize the conversion from low-voltage DC to high-voltage DC. Based on PSCAD/EMTDC, the simulation model of DCWT series-connected wind farm is built. Through the simulation of the DCWT of the wind system under steady-state operation conditions such as balanced output power, unbalanced output power, voltage fluctuation of high-voltage DC bus, and fault operation conditions such as dynamic cut-in and cut-out of faulted DCWT, it verifies the output characteristics of the DCWT, the operational characteristics of the system, and the processing capacity of the system for fault DCWT. This improves the operational reliability and flexibility of DCWT, and provides a practical solution plan for the construction of a DC wind farm. This work is supported by the National Key Research and Development Program of China (No. 2021YFB1507005).