Research on dynamic characteristics and countermeasures of AC-DC hybrid power system with large scale HVDC transmission

Voltage grade and capacity of HVDC transmission in China continue to increase these years. With the commissioning of UHV-HVDC transmission, voltage grade of HVDC has reached ± 800kV, and transmission capacity of single HVDC had reached 8000MW. Thus AC/DC interaction and its effects on system safety become a focal point on power system operation area. In this paper, based on operation practice of a large power grid and theory analysis, operation characteristics of HVDC with massive power transmission are illustrated, including over voltage control and multi-infeed HVDC system problems. A standpoint is proposed in this paper, that to build a strong sending and receiving AC power grid, is the fundamental measures to ensure grid safety with large scale power HVDC transmission.