适用于柔性高压直流输电网的直流电压下垂控制策略

基于带死区的直流电压下垂控制,提出一种适用于柔性直流输电网的新型直流电压下垂控制策略,可保障直流与交流系统交换功率的平衡。提出的新型直流电压下垂控制方法首先将各换流站分为4组,之后通过对各换流站组设定不同的电压裕度和死区来设定参与协调控制的不同优先等级,最后提出改进的"功率—电压"特性曲线来确保各换流站在暂态下具备良好的动态特性。仿真测试系统的交流部分为IEEE 39节点系统,直流部分为一个5端直流电网系统,其中换流器类型为401电平模块化多电平换流器。通过对该交直流混合系统的测试,文中提出的新型直流电压下垂控制方法可以在故障发生后有效地使系统过渡至新的稳态运行点。在暂态过程中,各换流站具备良好的动态特性。

DC Voltage Droop-control Strategy for VSC-based HVDC Grid

This paper introduces a new droop-based DC voltage control method, including the dead-band, for applications to the high-voltage direct current(HVDC)grid that utilizes the voltage-sourced converter(VSC)technology. The proposed droop-control also provides autonomous power balance for the HVDC grid. The droop-control method divides the VSC stations into four groups, activates the droop-control of each group based on a pre-specified voltage margin and uses an improved power-voltage characteristic for desirable VSC station dynamic performance. The feasibility and performance of the proposed control method are evaluated based on time-domain simulation studies on the PSCAD platform, using the IEEE 39-bus system in which a five-terminal, monopolar, VSC-HVDC grid is embedded. Each VSC station is a modular multilevel converter(MMC)with 401 levels. The study results show that the proposed droop-control method enables the HVDC-AC system to reach a new steady-state after transient events. This work is supported by State Grid Corporation of China(No. SGZJ0000BGJS1500265).