Virtual Inertia Control Strategy of Bidirectional Grid-Connected Converter Applying Multiple Sliding Mode Variable Structure Control

doi:10.12204/j.issn.1000-7229.2022.07.014

Abstract

Abstract:

Aiming at the problems of low inertia and poor anti-interference ability of bus voltage in DC microgrid, a virtual inertia control strategy based on multiple sliding mode variable structure control is proposed in this paper. Sliding mode current control based on the index reaching law is adopted in the inner loop, which can quickly track the given value of grid-connected current and improve the response speed of the system. Virtual inertia control equation and voltage sliding mode surface structure are established in the outer loop to enhance the inertia of the DC microgrid and suppress the fluctuation of the DC bus voltage. The stability of bidirectional grid-connected converter under the proposed control strategy is proved by small-signal disturbance method and Nyquist criterion. Finally, the corresponding simulation model and StarSim HIL hardware-in-the-loop experimental platform are built. The results show that, compared with the traditional virtual inertia control strategy based on PI control and passivity-based control, the proposed control strategy has better dynamic and static characteristics, and improves the stability of the DC bus voltage.

Key words: DC microgrid, bidirectional grid-connected converter, multiple sliding mode variable structure control, virtual inertia control

CLC Number:

TM46

LIU Yancheng, LÜ Xu, ZHANG Qinjin, HU Wangbao, ZHANG Hanwen. Virtual Inertia Control Strategy of Bidirectional Grid-Connected Converter Applying Multiple Sliding Mode Variable Structure Control[J]. ELECTRIC POWER CONSTRUCTION, 2022, 43(7): 121-130.

Figures/Tables 14

Fig.1 Diagram of DC micro-grid with BGC

Fig.2 Equivalent diagram of DC micro-grid with BGC

Fig.3 Block diagram of BGC system control

Fig.4 Small-signal model of d-axis current

Fig.5 Small-signal model of BGC system

Fig.6 Nyquist curve of BGC system

Table 1 Simulation parameters of BGC system

Fig.7 Comparison of DC bus voltage under three control strategies

Fig.8 Waveforms of grid-connected current and THD analysis under three control strategies

Table 2 Transient performance index of DC bus voltage under three control strategies

Fig.9 Dynamic response of DC bus voltage under different Cv

Fig.10 Experimental platform of BGC system based on StarSim HIL

Fig.11 Experimental waveforms of DC bus voltage when load power suddenly changes

Fig.12 Experimental waveforms of voltage and current at network side under different control strategies

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