Frequency Compensation of VSC-HVDC combined with Inertia Simulation: a Passivity-Based Control Approach

As the penetration of renewable energy sources using power electronics as an interface method in power systems increases, traditional synchronous generators are gradually being replaced, leading to a continuous reduction in power system inertia and a decrease in frequency support and oscillation suppression. In order to enhance the inertia support of VSC-HVDC systems, this paper proposes an interconnection and damping assignment passivitybased control (IDA-PBC) strategy based on inertia emulation. The strategy achieves inertia emulation control by releasing or absorbing inertial power through the DC capacitor, thereby suppressing frequency oscillations. As the inertial power released by capacitor charging and discharging is small and cannot maintain stability between interconnected power systems during large disturbances, IDA-PBC reshapes the energy of the system by injecting an interconnection matrix and a damping matrix to achieve matching of voltage and frequency between systems, which in combination with inertial simulation can improve the interconnectivity and stability between systems. Also in inertia emulation designs, PLLs are unable to accurately track system frequencies in weak grids and passive control can quickly adjust the output of the VSC-HVDC to achieve fast tracking. This fast response capability helps to reduce system oscillations and frequency excursions and improves system stability. Results from simulation and RT-LAB hardware-in-the-loop (HIL) testing attest to the efficacy of this solution.