多直流接入背景下的广东电网电压稳定特性研究

Research on Voltage Stability Characteristics of Guangdong Power Grid Under the Background of Multiple DC Access

随着多条直流馈入以及大规模海上风电的接入,广东电网呈现交直流耦合、多直流耦合及海风机组间相互耦合等复杂形势。大规模电力电子器件接入电网后,广东电网面临的主要运行风险有:特高压直流接入的负荷中心和直流近区交流线路发生三永N-2、N-4或三相短路中开关拒动故障后,引起交流电网持续低电压,导致电压失稳甚至电压崩溃;大电源或多电源集中接入的电网点及其近区500 kV变电站发生三相短路中开关拒动、同走廊组合故障后,引起系统发生功角失稳。对广东电网交直流故障进行仿真分析,针对电网薄弱环节,提出直流调制控制技术、切负荷措施及加装无功补偿装置等应对策略,以进一步提升电网的安全稳定水平。

With multiple DC-feeds and large-scale offshore wind power access,Guangdong power grid presents a complex situation of AC-DC coupling,multi-DC coupling and mutual coupling between wind turbines.After large-scale power electronic devices are connected to the power grid,the main operation risks of the Guangdong power grid are as follows.After the UHV DC access load center and DC near-area AC line have three permanent N-2,N-4 or three-phase short-circuit switch failure,the AC grid will continue to be low voltage,resulting in voltage instability or even voltage collapse.The power Angle instability of the system is caused by the switch rejection in the three-phase short circuit and the combined failure of the corridor in the 500 kV substation with the centralized access of large power supply or multiple power supplies.Based on the simulation analysis of AC and DC faults in Guangdong power grid,the corresponding countermeasures such as DC modulation control technology,load cutting measures and reactive power compensation device are proposed to further improve the security and stability of power grid.