Abstract
With a focus on the problems of active power sharing and voltage deviation of parallel-connected inverters in an islanded micro-grid (MG), in this study, the power-voltage droop controller and the inner voltage regulator are redesigned based on a total sliding-mode control (TSMC) technique. As for the power-voltage droop control loop, a droop control relation error between the active power and the point-of-common-coupling (PCC) voltage amplitude is defined. Then, the TSMC scheme is adopted to reach the new droop control relation, where the active power sharing and voltage amplitude recovery can be achieved simultaneously. Owing to the faster dynamic response and strong robustness provided by the TSMC framework, high-precision active power sharing during transient state also can be ensured without the influence of line impedances. The power allocation error can be improved by more than 81.2% and 50% than the conventional and proportional-integral (PI)-based droop control methods, respectively, and the voltage deviation rate can be reduced to 0.16%. Moreover, a small-signal model of the TSMC-based droop-controlled system is established, and the influences of control parameters on the system stability and the dynamic response are also investigated. The effectiveness of the proposed control method is verified by numerical simulations and experimental results.
Highlights
As with the control technology for parallel-connected inverters, the droop control has been widely used in the micro-grid (MG) [1,2,3,4]
Since the voltage tracking performance can be reflected by the records of the root-mean-squared error (RMSE), the voltage RMSEs with the two methods are calculated as RMSE = 6.090 and RMSE = 5.957 for the quasi-PRC scheme; RMSE = 2.468 and RMSE = 4.105 for the proposed total sliding-mode control (TSMC) framework
A total-sliding-mode-control (TSMC)-based P-U/Q-f droop control structure has been successfully designed for the parallel-connected inverter system to achieve the objectives of accurate power sharing and high voltage quality
Summary
As with the control technology for parallel-connected inverters, the droop control has been widely used in the micro-grid (MG) [1,2,3,4]. For the islanded operation mode, the droop control can maintain the voltage amplitude/frequency stability and adjust the power allocation proportion among multiple inverters simultaneously [5]. For a MG with a medium or low voltage, the system impedance generally exhibits a complex impedance characteristic. The virtual impedance with different components is often introduced to change the impedance characteristics of the system [6,7,8]. The virtual impedance method may bring about a voltage drop on the voltage reference, which will deteriorate the voltage quality, and make the voltage more sensitive to the change of load currents
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
