Abstract
As an interface between distributed power source and large power grid, microgrid has attracted more and more attention. Due to the lack of inertial support for the power system, the virtual synchronous generator (VSG) technology that can simulate the external characteristics of synchronous generators came into being. Aiming at the problem of power and frequency oscillation in microgrid after the introduction of VSG technology, this paper conducts small-signal modeling of multiple VSGs in parallel, analyzes their operating characteristics, and proposes a multiple VSGs cooperative control strategy based on adjacent information. Depend on the adjacent information, the strategy optimizes the output control of each VSG, which makes each VSG tend to the same output frequency at any time. Therefore, the proposed strategy can suppress the power and frequency oscillation, and improve the dynamic characteristics of the system. In this paper, the stability of the proposed control strategy is studied by Lyapunov stability theory, and the effectiveness of the proposed control strategy is verified by simulation.
Highlights
Facing the increasingly severe energy crisis, distributed power generation technology based on renewable energy has received more and more attention
Each single virtual synchronous generator (VSG) obtains adjacent frequency information through intercommunication, thereby the local VSG output control is improved to make each VSG tend to have the same output frequency at any time. This strategy alleviates the problem of uneven instantaneous active power distribution among VSGs and overshoot of instantaneous frequency in microgrid under disturbance, thereby it can effectively suppress system oscillation
In order to improve the stability of the system, the microgrid's multiple VSGs cooperative control strategy based on adjacent information is considered
Summary
Facing the increasingly severe energy crisis, distributed power generation technology based on renewable energy has received more and more attention. In [18], a new VSG control structure is formed by introducing the virtual inertia into the feedback control loop of VSG This proposed method can improve the transient performance of frequency deviation suppression, but the realization of control structure is rather complicated. The virtual resistance is adaptively designed according to the operating point of the microgrid, so as to alleviate the impedance difference at the output of the inverter and improve the proportional reactive power distribution between DGs. Each single VSG obtains adjacent frequency information through intercommunication, thereby the local VSG output control is improved to make each VSG tend to have the same output frequency at any time This strategy alleviates the problem of uneven instantaneous active power distribution among VSGs and overshoot of instantaneous frequency in microgrid under disturbance, thereby it can effectively suppress system oscillation. In view of possible communication failures, this paper verifies the superiority of the proposed strategy by comparing the simulation results under different control strategies
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