应对受端交流故障的海上风电柔直并网系统主动能量控制方法

Active Energy Control of Offshore Wind Power MMC-HVDC System to Handle AC Faults of Receiving-end Power Grid

在海上风电柔直并网系统中,交流故障期间盈余功率的快速耗散是保证系统故障穿越性能及运行可靠性的主要技术途径。针对现有盈余功率耗散方案中存在通讯可靠性低、响应时间长、技术成本高及能量浪费等问题,提出一种基于主动能量控制的盈余功率主动回收方法。首先,通过分析不同交流故障类型下的故障电路,定量地验证利用柔直系统的能量裕度对盈余功率进行回收的可行性。随后,提出基于直流调制比的换流器解耦控制策略,并在此基础上设计能量回收方案及直流耗能装置协调控制策略。最后,通过在PSCAD/EMTDC中搭建典型海上风电柔直并网系统的仿真模型,对不同时长、不同故障类型的交流故障进行仿真,验证所提主动能量控制及能量回收方案的有效性。

In the offshore wind power integrated modular multilevel converter(MMC)-HVDC system,the rapid dissipation of surplus power during onshore grid faults is a major technical challenge.Since existing power dissipation schemes suffer from the deficiencies of low communication reliability,long response time,high cost and energy waste,this paper proposes an energy utilization method based on active energy control.First,the feasibility of energy utilization method is quantitatively verified by analyzing the fault circuits under different AC fault types.Then,the decoupling control strategy of MMC based on DC modulation ratio is proposed.On this basis,the energy utilization algorithm and the coordination control strategy of DC energy dissipation device are designed.Finally,a simulation model of the typical offshore wind power integrated MMC-HVDC system is built in PSCAD/EMTDC to verify the effectiveness of the proposed active energy control and energy utilization schemes.