Abstract
The centralized control mode is no longer applicable for microgrid operation due to the high penetration rate of distributed energy, which is responsible for the widespread interest in the use of the distributed microgrid. Focusing on the issues of power coupling and uncontrollable droop coefficient at the terminal of the connecting line between the micro-source and AC bus, which is rarely considered, this paper proposes an improved virtual synchronous generator (VSG) control strategy based on local data considering precise control of the droop coefficient and realizing the power decoupling and the expected droop characteristics. Then, combined with the virtual rotor characteristic matching method, the reasonable active and reactive power sharing of the parallel microgrid inverters are realized in terms of static and dynamic performance without additional improvement of reactive power control. Finally, the effectiveness and feasibility of the proposed method are verified based on the MATLAB/Simulink simulation platform. The combination of the proved strategy and matching principle endows inverters with self-synchronization characteristics, forming the self-synchronizing voltage sources, which gives the distributed microgrid a higher self-stability, autonomy and robustness to ensure the stable operation of the microgrid.
Highlights
In order to alleviate the impact of a growing number of distributed generations (DGs) accessing power grids, the concept of a microgrid is proposed [1,2,3]
In order to verify the effectiveness of the improved virtual synchronous generator (VSG) control strategy and the matching principle proposed in this paper, the model of the self-synchronizing voltage source in the distributed microgrid is built based on the MATLAB/Simulink simulation platform
The islanding microgrid model with two self-synchronizing voltage sources in parallel operation is established, as shown in Figure 5 To verify the effectiveness of the proposed scheme, the power sharing performances at the terminal of the connecting line adopted by different methods are analyzed in comparison, including without the decoupling control method, with the virtual impedance method, and with the improved VSG control method combined with the matching principle
Summary
In order to alleviate the impact of a growing number of distributed generations (DGs) accessing power grids, the concept of a microgrid is proposed [1,2,3]. Based on the above analysis, in terms of the terminal power decoupling and droop effect of the connecting line, an improved VSG control strategy considering the precise control of droop coefficient is proposed in this paper. It realizes active and reactive power decoupling as well as expected droop characteristics on the user side under the premise of using local data. Combined with the virtual rotor characteristic matching principle, the multi-paralleled inverter voltage sources have the capability to achieve reasonable and accurate sharing of active and reactive power at steady-state level and dynamic-state level autonomously without a master controller in order to realize long-term stable synchronous operation, which can be defined as self-synchronous characteristic. Natick, MA, USA) platform are presented in Section 4, followed by the conclusion in
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