ILADRC resonance suppression control strategy for multiple parallel photovoltaic energy storage GFL VSG microgrid

High proportion of distributed photovoltaic integration into power system has led to power system presenting weak or extremely weak power grid state. Under weak power grid or grid harmonic background high penetration distributed photovoltaic GFL converters are prone to lead to system instability. To suppress distributed photovoltaics grid connection resonance, ILADRC method multiple parallel photovoltaic storage GFL VSG system control strategy is proposed. Firstly, stability analysis of single photovoltaic energy storage GFL VSG system and multiple parallel photovoltaic energy storage GFL VSG system is, respectively, performed. Through impedance stability analysis, it can be concluded that multiple parallel photovoltaic energy storage GFL VSG system is prone to resonance in weak power grid or grid harmonic background. Secondly, to suppress system resonance, ILADRC GFL VSG controller is designed, and ILADRC photovoltaic energy storage GFL VSG system impedance model is established for stability analysis. System output impedance amplitude of LADRC method is larger than that of LADRC/unimproved method, and it has a stronger ability to attenuate harmonics in the power grid. Finally, ILADRC multiple parallel photovoltaic energy storage GFL VSG simulation model and hardware in the loop experimental platform are established for tests. By tests shows that harmonic content of unimproved method system is, respectively, as high as 26.57% and 24.29% under weak power grid and grid harmonic background, LADRC method system harmonic content is, respectively, 6.78% and 10.57% under weak current and grid harmonic background, ILADRC method system harmonic content is, respectively, reduced to 1.55% and 2.55% under weak power and grid harmonic background. This indicates ILADRC method system has better resonance suppression ability under weak current net or grid harmonic background, compared to LADRC/unimproved method.