Search

• Multi-damping factor design method for PBC of SPVSI with LC filters. • Ensure the stability of islanded SPVSI system under various load scenarios. • Ensure the stability of islanded SPVSI system under LC filter parameter drift. • Adopting a design sequence from the inner to the outer control loop. • Design of control loops with good performance and distinct control bandwidth. With the advantages of fast response, good stability, and strong robustness to filter parameter variations as well as load perturbations, the application of passivity-based control (PBC) in the single-phase voltage source inverter (SPVSI) has received extensive attention. However, as a non-linear control strategy, PBC control has a complex coupling structure containing feed-forward, negative feedback, etc., which poses many difficulties for multi-damping design. In addition, ensuring the passivity of the islanded system under various load conditions or filter parameter drift is still an unresolved issue in the damping coefficient design of the PBC controller. Therefore, for SPVSI systems with LC filters, this paper proposes a multi-damping coefficient design method for PBC controllers based on stability domain analysis. The designed PBC controller can ensure system stability under several load conditions or certain deviations of LC filter parameters. Moreover, the design order from the inner to the outer control loop is adopted according to the distribution of individual damping coefficients in the control loop. As a result, each control loop has a good dynamic performance and distinct control bandwidth. Finally, robustness analysis, simulation, and experimental results verify the correctness and effectiveness of the proposed multi-damping coefficients design method for the PBC controller. [ABSTRACT FROM AUTHOR]

• Based on impedance model of two-stage PV inverter in frequency domain, the passive equivalent impedance network of PV inverter connected to power grid is built. • The harmonic amplifying characteristic curve of PCC in full frequency range is established, and the influence of inverter parameters, reactive power compensation device and distributed transmission line model on harmonic characteristics is deeply analyzed. • A harmonic mitigation control strategy with superimposed multi-current resonance controllers and active damping controllers in synchronous rotating coordinate system is proposed, and the effectiveness of this control strategy is verified by simulation. To investigate the harmonic characteristics of a photovoltaic (PV) system connected to the weak grid, a passive impedance network is constructed using the impedance model of a PV inverter in the positive and negative sequence coordinate system. By analyzing the series resonance of the impedance network, the amplification coefficient of the harmonic voltage at the point of common coupling (PCC) is obtained. In addition, the effects of different PV inverter parameters, different reactive power compensation capacities, and different lengths of distributed transmission lines on the harmonic amplification are analyzed in detail. To solve the problem that the output harmonics exceed the standard under the background harmonic condition of the weak grid, a harmonic mitigation control strategy is implemented. This strategy is designed based on multiple resonant current controllers and active damping feedback to improve the ability of the PV inverter to suppress harmonics under the grid background harmonic conditions. The effectiveness of the harmonic mitigation control strategy is demonstrated by the simulation example of the inverter connected to the grid with symmetric and asymmetric background harmonics, respectively. [ABSTRACT FROM AUTHOR]