  Small-signal synchronization instability (SSI) may be triggered when a
grid-connected converter is operated in weak grids. This problem is highly
related to the active and reactive power (referred to as complex power)
generation or consumption of the converter. Such an instability phenomenon
manifests as power oscillations within the bandwidth frequency of phase-locked
loop (PLL). However, in a multi-converter power system (MCPS), it is
challenging to characterize the role of each converter's complex power in SSI
issues due to the high dimension of system dynamics. In this paper, we focus on
the impact regularity of complex power on the small-signal synchronization
stability of the MCPS. Firstly, we formulate the modeling of the MCPS and
develop a systematical stability indicator to explicitly quantify the stability
margin under various operating complex power. Then, based on the proposed
stability indicator, the "resultant force" of complex power on the stability
margin of the MCPS can be analytically characterized into a weighted summation
form. Furthermore, we elaborate on the impact of each converter's active power
and reactive power, respectively. Notably, we demonstrate the cancellation
effect between the active power generation and consumption on the stability
margin, which ultimately helps prevent SSI issues in the MCPS. The correctness
of theoretical findings is well verified by simulations results.
