多直流馈入系统不同电网分区方式比较

电网分区是提高多直流馈入系统稳定性能的有效途径，为研究不同电网分区方式对实际电网性能的提升效果，以广东电网2030年规划方案为例，将传统直流分区、柔性直流分区和动态分区三种方式应用于实际电网，分别针对单通道和双通道互联方案，从多直流落点有效短路比、交流故障对直流的影响和短路电流控制水平三方面对不同电网分区方式下的电网性能进行了计算和比较。结果表明：不同分区方式对实际电网性能影响不同。柔性直流分区方式在多直流落点有效短路比、交流故障对直流的影响和短路电流控制水平3方面表现更好；动态分区在控制短路电流水平方面具有一定的作用；传统直流分区方案能够有效减小短路电流水平，同时也能够限制交流故障下发生换相失败直流的最大数量。对于广东电网的规划方案，双通道互联方案下的柔性直流分区方式对系统性能提升效果最为明显。

Comparison of Different Grid Segmentation Techniques in Multi-infeed HVDC Systems

Grid segmentation is an effective technique to improve the performance of multi-infeed HVDC systems. To study the performance improvement of different kinds of grid segmentation techniques in real power grids, the planning scheme of Guangdong Power Grid in 2030 is taken as an example, traditional LCC-HVDC (line-commutated converter HVDC) segmentation method, VSC-HVDC (voltage source converter HVDC) segmentation method and dynamic segmentation method are applied to the single corridor interconnection schemeand double corridor interconnection scheme respectively. The power grid's performances are calculated and compared from three aspects: multi infeed effective short-circuit ratio, impact of AC faults on DC systems, and short-circuit current control. Results show that different grid segmentation techniques have different impacts on the real power grid's performance: the VSC-HVDC segmentation method performs better in all three aspects; the dynamic segmentation method is effective in controlling short-circuit current to a certain extent; the traditional LCC-HVDC segmentation method is effective both in reducing the short-circuit curent and in limiting the maximum number of DC system having commutation failure in AC faults. As for the the planning scheme of Guangdong Power Grid, the VSC-HVDC segmentation method improves the grid performance better than other methods under the double-corridor interconnection scheme.