A DMPC-Based Secondary Harmonic Compensation Strategy via Adaptive Virtual Admittance Tuning

A large number of grid-connected inverters have been connected to distribution networks and can be used to mitigate harmonics at the system level. Deploying distributed power electronic devices for harmonic mitigation is a cost-effective solution for distribution networks. However, existing coordination methods typically depend on highly reliable, low-latency communications. Communication delays or interruptions can significantly degrade coordination performance and even exacerbate harmonic distortion. This paper presents a hierarchical, coordinated harmonic compensation method for multiple multifunctional grid-tied inverters (MFGTIs). At the primary control level, harmonic domain virtual admittance is incorporated, enabling each device to adaptively inject harmonic compensation currents using only local measurements, maintaining baseline compensation capability when communication is limited or interrupted. At the secondary control level, a distributed model predictive control (DMPC) scheme is derived from the harmonic steady-state equivalent circuit. The virtual admittance parameters are updated iteratively using measurements exchanged only among neighboring nodes, enabling coordinated sharing of compensation currents without requiring global information or frequent harmonic power flow calculations. Case studies demonstrate that the proposed method reduces nodal harmonic voltages under communication constrained conditions while significantly lowering the computational burden.