In new islanded energy power systems with high penetration of inverter-based resources (IBRs)

insufficient system inertia support increases the risk of frequency instability. Fixed-frequency control can ensure the system frequency constancy through a globally unified synchronous rotating coordinate system

but there is still the problem of coordinating multiple IBR units for a single voltage variable. This paper focuses on the power coupling and distribution inadequate accuracy of fixed-frequency control caused by the line impedance mismatch in medium-and low-voltage power grids. We construct a d/q-axis equivalent output impedance model based on fixed-frequency virtual impedance interaction mechanism

and put forward an improved virtual impedance droop control strategy. The strategy achieves power decoupling by adopting virtual reactance compensation

and optimizes the d/q-axis virtual resistance parameters based on IBR capacity and line resistance. The small-signal stability analysis verifies the feasible domain of virtual impedance parameters

and Simulink parallel simulation shows that the proposed strategy maintains the power allocation error at about 1% under the extreme working conditions of large deviation between IBR capacity and line impedance

and has the flexibility of fixed-frequency control

which significantly outperforms the traditional fixed-frequency control method in dynamic performance.