A Current Indirect Feedforward Control Strategy for Enhancing Voltage Stability of DC Microgrid

In the dc microgrid based on the droop control, the dc bus voltage quality is greatly affected by the type of loads. First, based on the impedance analysis method, the voltage distortion and oscillation characteristics of the dc microgrid are analyzed. Due to the large equivalent impedance of the energy storage converter (ESC), a large distorted voltage on the ESC will be caused by harmonic loads. Meanwhile, due to the negative damping characteristics of constant power loads, the dc microgrid is prone to oscillation. To address the above issues, a current indirect feedforward control strategy of the ESC is proposed by estimating and feeding forward the current on the low-voltage side of the boost circuit. Meanwhile, an inertial controller is designed and embedded between the voltage and current loops, which can enhance the voltage stability of the dc microgrid. From a circuit perspective, the equivalent impedance of the improved ESC is smaller and more like an ideal dc voltage source, making the dc microgrid voltage more stable. Finally, the proposed control strategy and theoretical analysis are verified by simulation and experiment.