Abstract
This paper proposes an inductor current sensorless control strategy based on modified virtual synchronous generator (VSG) method for single-phase inverter-interfaced microgrid application. Firstly, the outer power loop with Q-U integral term is presented for output reactive power enhancement, and an inner voltage regulation loop based on luenberger state observer is proposed to reduce the inductor current sensor. Meanwhile, in order to improve the response speed of the observer, the luenberger observer is designed based on the optimal pole assignment method. Secondly, a seamless switching strategy based on the modified VSG method is proposed, which can realize the seamless transition between the island mode and grid-connected mode. Finally, a single-phase 3kW VSG prototype is built, and the effectiveness and correctness of the proposed control strategy is verified by the simulation and experimental results.
Highlights
With the increasing popularity of distributed power sources (Valinejad et al, 2020; Canziani et al, 2021), microgrid based on these distributed generations (DGs) has become an effective power supply supplement for the main power grid (Wang et al, 2015; Qazi et al, 2021)
In order to verify the effectiveness of the above-mentioned luenberger observed-based virtual synchronous generator (VSG) strategy, a 3kVA simulation model based on the single-phase inverter was built
The simulation results demonstrate that when the single-phase VSG switches between the two operating modes, there is no obvious power mutation and the output power of the VSG can reach the reference power in grid-connected mode
Summary
With the increasing popularity of distributed power sources (such as photovoltaic panels, fuel cells, wind turbines etc.) (Valinejad et al, 2020; Canziani et al, 2021), microgrid based on these distributed generations (DGs) has become an effective power supply supplement for the main power grid (Wang et al, 2015; Qazi et al, 2021). Reference (Zhao et al, 2017) presents a method based on virtual power calculation to realize the seamless transfer between islanded/grid-connected mode and enhance the stability of single-phase microgrid Most of these control strategies mentioned above require the knowledge of the output voltage, load current and inductor current to achieve power/voltage asymptotic tracking. A modified VSG strategy with the inductor current observer is proposed for single-phase inverter application, and it can be summarized as follows: 1) The improved algorithm for single-phase VSG has the ability to simulate the frequency and voltage characteristics of SG, and it can achieve the zero-steady-error tracking of the reference output reactive power when the VSG operates in grid-connected mode.
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