Analysis of Hybrid Multi-Infeed HVDC Transmission Technology and Power Coordinated Control Strategy of Near Area Power Grid

For the Hybrid MIDC (multi-infeed HVDC) transmission system, the electrical coupling between the converter stations is tight, and the interaction between the AC and DC systems is more complicated. It is necessary to conduct in-depth analysis and research on the dynamic operation characteristics and power coordination control strategy of Hybrid MIDC power transmission system in combination with specific projects. This paper summarizes the problems of power oscillation and emergency DC power support in MIDC transmission systems and their research status. Then, taking a typical double-infeed DC transmission project as an example, an electromagnetic transient simulation model including three-region AC power grids, LCC-HVDC and VSC-HVDC transmission systems is established. The power step response characteristics of LCC-HVDC and VSC-HVDC systems are compared through simulation analysis. For Hybrid MIDC, this paper proposes a coordinated control strategy for emergency power support between flexible DC and nearby conventional DC & AC systems. Finally, it is verified that it can improve the stability of the power system to a certain extent through the simulation test of the trip fault of the AC system generator set.