Stability analysis and nonlinear current-limiting control design for DC micro-grids with CPLs

IET Smart Grid

George C. Konstantopoulos¹  Andrei-Constantin Braitor¹  Visakan Kadirkamanathan¹ 

[1] The University of Sheffield;

关键词: cascade control;    nonlinear control systems;    voltage control;    ac-dc power convertors;    control system synthesis;    power distribution control;    electric current control;    closed loop systems;    power generation control;    distributed power generation;    dc-dc power convertors;    power system stability;    control design;    cpl;    dc microgrid architecture;    multiple paralleled energy resources;    constant power load;    nonlinear model;    control schemes;    converter-interfaced unit;    load voltage regulation;    power sharing;    closed-loop system stability;    novel control framework;    input-to-state stability theory;    converter unit;    current limitation;    cascaded control;    dc microgrid instability;    system performance;    control performance;    theoretical stability analysis;    traditional cascaded pi control technique;    control approach;    droop control expressions;   

DOI  :  10.1049/iet-stg.2019.0235

来源: DOAJ

【 摘 要 】

In this study, a DC micro-grid consisting of multiple paralleled energy resources interfaced by both bidirectional AC/DC and DC/DC boost converters and loaded by a constant power load (CPL) is investigated. By considering the generic dq transformation of the AC/DC converters' dynamics and the accurate nonlinear model of the DC/DC converters, two novel control schemes are presented for each converter-interfaced unit to guarantee load voltage regulation, power sharing and closed-loop system stability. This novel framework incorporates the widely adopted droop control and using input-to-state stability theory, it is proven that each converter guarantees a desired current limitation without the need for cascaded control and saturation blocks. Sufficient conditions to ensure closed-loop system stability are analytically obtained and tested for different operation scenarios. The system stability is further analysed from a graphical perspective, providing valuable insights of the CPL's influence onto the system performance and stability. The proposed control performance and the theoretical analysis are first validated by simulating a three-phase AC/DC converter in parallel with a bidirectional DC/DC boost converter feeding a CPL in comparison with the cascaded PI control technique. Finally, experimental results are also provided to demonstrate the effectiveness of the proposed control approach on a real testbed.

【 授权许可】

Unknown