构网型柔性直流系统阻尼环节控制策略优化研究

Optimization of Damping Control Strategy for Grid-forming VSC-HVDC

采用构网控制的柔性直流输电系统可模拟同步电机运行特性,为电网提供频率和电压支撑,而传统的功率同步型构网控制阻尼环节引入了调频功能,使柔直功率输出随电网频率变化而波动。该文基于同步发电机调频和阻尼环节的机理辨析,提出了功率同步型构网控制阻尼环节改进方法,可同时满足并网运行稳态功率精准控制和频率突变的阻尼需求,并基于小信号稳定分析给出了控制参数设计原则,基于电磁暂态仿真平台以及渝鄂柔性直流工程现场试验验证了改进策略的有效性。

The general grid-forming VSC-HVDC system can provide frequency and voltage support for the system by simulating the characteristics of synchronous generators.However,in the conventional power synchronous grid-forming control,due to the adoption of the frequency regulation into the damping unit,the power of the VSC-HVDC often fluctuates with the frequency variation.Based on the mechanism and analysis of the synchronous generator frequency regulation and the damping part,the optimized damping control strategy with the grid-forming control is proposed,meeting the requirements of the precision control and the damping demand with a sudden power mutation at the same time.Then the design principles of the damping coefficients and the filtering time constant are proposed by using the small signal stability analysis.Finally,the effectiveness of the proposed strategy is demonstrated by the electromagnetic transient simulation and the field test in the YU-E(Chongqing-Hubei)VSC-HVDC project.