Abstract
To adapt to the rapid development of the renewable generations, DC micro-grid has been becoming an attractive technical route. Energy storages are widely employed in DC micro-grid to balance the power generation and usage. Therefore, the coordination and energy control among these distributed energy storage systems are critical technical issues to guarantee the overall efficiency and security. In this paper, the concept and characteristic of the distributed energy storage system in DC micro-grid are first analyzed. A hierarchical control system for power sharing is proposed to achieve the state-of-charge (SOC) balancing among energy storage units (ESU). In the lower layer of the control system, the DC droop control is applied to allocate the output power of each ESU based on its maximum output power. In the upper layer, consensus algorithm is utilized to adjust the output power reference of each ESU to reduce the SOC difference. Finally, a Matlab/Simulink model is built to verify the proposed approaches. The simulation results indicate that the proposed method can achieve the SOC balancing robust operation in distributed energy storage system.
Highlights
Micro-grid provides an effective solution to integrate distributed energy resource, including renewable generations, controllable loads and energy storage systems, into power system
The power allocation SOC balancing scheme among distributed generations and energy storage units (ESU) in micro-grid is realized through the control methods of power converters, which can be roughly divided into three categories: centralized, decentralized and distributed [5]
This paper focuses on exploring an effective control method to achieve SOC balance among distributed ESUs in a micro-grid
Summary
Micro-grid provides an effective solution to integrate distributed energy resource, including renewable generations, controllable loads and energy storage systems, into power system. To satisfy the power demand of the overall micro-grid coordinately, the output of each ESU should be allocated reasonably to maintain its. The power allocation SOC balancing scheme among distributed generations and ESUs in micro-grid is realized through the control methods of power converters, which can be roughly divided into three categories: centralized, decentralized and distributed [5]. Jiang et al.: Hierarchical Control Structure for Distributed Energy Storage System in DC Micro-Grid integrate multiple energy sources in a micro-grid [12]–[15] It is a control method which regulates the voltage and current references of the converter according to certain droop curves. A hierarchical control structure is proposed to allocate power rationally to realize the SOC balancing while meet the overall power demand for the energy storage system. If the droop coefficient is set by the ratio of the maximum power Pmax of each ESU, the dynamic out power of ESUs can be allocated proportionally: Po1 Pmax
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