Analytic Quantification of Interactions in MTDC Systems Based on Self-/En-Stabilizing Coefficients in DC Voltage Control Timescale

Multiterminal high-voltage direct-current (MTDC) systems based on voltage-source converters (VSCs) are used for the transmission of large-scale renewable energy generations. Dynamic interactions among different VSCs through the coupling of DC and AC networks become one salient problem in an MTDC system. Self- and en-stabilizing coefficients, which are expressed analytically in the frequency domain with clear math and physical meanings, are defined to quantitatively describe and analyze the interactions of an MTDC system in this article. Some insights behind such interactions are concomitantly revealed by the analytic quantification. In this course, it not only points to the devices and interaction paths causing the oscillations but also illustrates how controller parameters affect the system stability by analytic expressions. This method provides an analytical way to quantify the interactions among VSCs in DC voltage control timescale, henceforth leaving a deeper understanding of the dynamics in an MTDC system.