Research on Voltage Stability Characteristics of Guangdong Power Grid Under the Background of Multiple DC Access
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.
multiple DC connectionsthree-phase short circuitvoltage instability
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