Abstract
In order to improve the transient stability of frequency in a small stand-alone microgrid (SSM), this paper takes a SSM composed of a direct-drive permanent magnet synchronous generator (D-PMSG) and a micro gas turbine (MGT) as the background and uses wind turbine generator (WTG) virtual inertia (VI) to participate in the primary (short-term) system frequency regulation. First of all, this paper constructs a grid-connected model composed of a WTG and a MGT, analyzes the WTG virtual inertia frequency regulation mechanism, and explains the principle of proportional-differentiation (PD) virtual inertia control (VIC) and its shortcomings. Secondly, the paper introduces the structure principle of n-order active disturbance rejection control (ADRC) and deduces the design process of second-order ADRC-VIC. Finally, through the simulation and experimental verification, comparing the frequency perturbation of without-VIC, PD-VIC, and ADRC-VIC, it is concluded that PD-VIC and ADRC-VIC both can use the WTG virtual inertia to participate in the primary frequency regulation. The frequency regulation effect of ADRC-VIC is better than PD-VIC, ADRC-VIC can extend the rotor speed recovery time and avoid overshoot, and its frequency fluctuation amplitude and settling time are obviously improved, and ADRC-VIC can effectively avoid the overshoot phenomenon of the MGT output power.
Highlights
The small stand-alone microgrid (SSM) is an effective way to solve the power supply in the mountains, islands, and remote areas
Compared with that in PD-virtual inertia control (VIC), PMGT does not appear overshoot phenomenon, PMGT can be more smooth added to 12 kW, and second-order active disturbance rejection control (ADRC)-VIC reduces the impact of load disturbance on Micro gas turbine (MGT)
As wind turbine generator (WTG) uses second-order ADRC-VIC to increase the intensity of participating in the frequency regulation, the disturbance range of the rotor speed ωw becomes larger, which indicates that WTG virtual inertia can be more fully released
Summary
The small stand-alone microgrid (SSM) is an effective way to solve the power supply in the mountains, islands, and remote areas. One is called deloaded operation of WTG; when the system frequency has a deviation, Mathematical Problems in Engineering the WTG releases the standby power to participate in the system frequency regulation This process takes a long time, but it is at the expense of wind energy utilization and the operating economy of WTG, and it is difficult to promote the application. The permeability of wind power is often larger due to the limited capacity of SSM, which ensures the effectiveness of WTG participating in the system transient frequency regulation [15,16,17]. Many scholars have started the research on how to use the virtual inertia of WTG in the system frequency regulation and improve the transient stability of frequency.
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