Small Signal Stability Analysis Of The Energy Storage Main Power In PV Energy Storage Microgrid That Working In Islanded State

As an important part of smart grid construction, the microgrid has a lot of advantages, which consist of make the distributed power access conveniently, improve energy efficiency, flexible operation, and realize high schedulability,selfcontrol, protection, management, etc. And the microgrid in islanding operation state has the advantages that ensure the power supply of key loads when the power grid is in fault, improve the reliability of power supply and solve the problems of users who live in remote areas like desert or island. In this paper, take the PV energy storage microgrid that working in islanding operation state for instance to study, the main research contents are as follows:Firstly, study on the control strategy of the power generation unit in the islanded microgrid, the photovoltaic power unit with constant power control as the secondary power unit access to microgrid, ensure the full, efficient use of renewable energy; the energy storage unit through the droop control in parallel as the main power unit access to microgrid to support the voltage and frequency for the microgrid, at the same time, improve the power characteristics of the microgrid. In the inverter control of the energy storage unit, by citing the virtual impedance to improve the power sharing problems and the circulation problems caused by the line impedance difference;by citing the quasi proportional resonant control technology to realize the voltage track without static error in a wide frequency band, reduce the circulation caused by voltage deviation.Secondly, based on the determining structure and control strategy of the microgrid, make the small signal stability analysis for the ennrgy storage unit, the very important component in microgrid that working in islanding state.In this paper, the small signal stability analysis are based on the impedance analysis method proposed by Middlebrook et al. On the basis of introduction and analysis to the traditional impedance analysis method, proposing the small signal stability analysis method aiming the multi-source and single-load network, and proving the correctness of this method in theory. The method is applied to the energy storage unit to analysis the small signal stability, studied the effects of different parameters change, for example, inverter controller parameters change, the filter parameters change and the virtual impedance parameters change.Finally, conduct the transient simulation by using the Matlab/Simulink simulation software to prove the correctness of the control strategy and the small signal stability analysis method proposed in this paper.