Reactive voltage support strategy for droop-controlled grid-forming converters based on LADRC

To enhance the low-voltage ride-through (LVRT) capability of emerging power systems with increasing penetration of renewable energy while addressing issues such as the slow response speed of traditional proportional-integral (PI) control, high model accuracy requirements, and complex system parameter tuning, this paper proposes a droop-controlled converter reactive power support strategy based on first-order linear active disturbance rejection control (LADRC). First, a mathematical model of a droop-controlled grid-forming (GFM) converter is established. A model equivalence method is then proposed to transform the dynamic characteristics of the control loop into equivalent impedance parameters. Based on the equivalent impedance parameter model, the influencing factors of the converter terminal voltage and point of common coupling (PCC) voltage are derived. Next, a first-order linear active disturbance rejection control strategy is introduced into the traditional droop control framework, and the controller parameters are optimized via the bandwidth tuning method. Finally, a simulation model of the droop-controlled GFM converter based on the linear active disturbance rejection controller is constructed on the PSCAD/EMTDC platform, and through comparative experiments under typical grid fault conditions, the effectiveness of the proposed control strategy in improving the system fault ride-through capability and voltage support is verified.