Intercommunication-free distributed direct-current energy storage system and control method therefor

Abstract

The invention discloses an intercommunication-free distributed direct-current energy storage system and a control method therefor. A current ratio is output according to a converter of an energy storage unit, virtual resistors with a state of charge of the energy storage unit and line impedance in charging and discharging conditions are designed separately, and load power dynamic distribution in the distributed direct-current energy storage system is realized without a communication system; and meanwhile a local voltage secondary controller is added, so that a voltage drop caused by a droop control method can meet a maximum voltage deviation requirement of the system. According to the distributed direct-current energy storage system and the control method, the present problems that the energy storage unit cannot dynamically distribute load power according to a current state of charge due to the fact that a control policy balances an output voltage of a distributed power supply by depending on the communication system and the influence of the line impedance on output current distribution precision of the energy storage unit is not considered can be comprehensively solved.

Description

technical field [0001] The invention belongs to the technical field of distributed power generation control systems, and in particular relates to a distributed DC energy storage system without interconnection and communication and a control method thereof. Background technique [0002] For distributed power sources connected to the DC microgrid system, the instability and randomness of renewable energy will have a greater impact on the reliability of the power supply of the microgrid. Connecting the energy storage units to the DC bus in a distributed manner can stabilize the power fluctuation of the system and improve the stability of power supply. Due to the existence of line impedance in the distributed system, the current distribution accuracy of the energy storage unit will decrease, resulting in a decrease in the balance effect of the load power among converters with different interfaces. [0003] At present, there are few studies on the consistency control of distribu...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the above problems, the present invention proposes a distributed DC energy storage system and its control method without interconnection communication, which can comprehensively solve the existing control strategy relying on the communication system to balance the output voltage of the distributed power supply, which cannot realize energy storage The unit dynamically allocates load power according to the current state of charge, and fails to consider the influence of line impedance on the output current distribution accuracy of the energy storage unit

Images