Bus Voltage Control Strategy for Low Voltage DC Microgrid Based on AC Power Grid and Battery

Author(s):  
Zhongtian Zhao ◽  
Jian Hu ◽  
Hongtao Chen
2020 ◽  
Vol 185 ◽  
pp. 01064
Author(s):  
Yilonɡ Kanɡ ◽  
Ningkang Zheng ◽  
Xiangyang Yan ◽  
Huanruo Qi ◽  
Kai Li

It is important to achieve stability of bus voltage in control of DC microgrids. In the DC microgrid, the traditional droop control method is usually adopted to stabilize the bus voltage for its high reliability and cost-effectiveness. However, line resistance will reduce the voltage quality of the DC bus in actual situations. In order to improve the voltage quality of the DC bus, a novel bus voltage control strategy based on modified droop characteristic is proposed. Finally, the simulation model of the off-grid DC microgrid with improved droop control strategy is built on PSCAD/EMTDC platform, and the results verify the effectiveness and feasibility of the proposed control strategy.


2020 ◽  
Vol 185 ◽  
pp. 01061
Author(s):  
Ningkang Zheng ◽  
Xiangyang YanHuanruo ◽  
Huanruo Qi ◽  
Yilong Kang

In an isolated DC microgrid consisting of photovoltaic cells, an energy storage unit and load, reasonable control of grid-connected two-way AC/DC converter can effectively realize coordinated power distribution and bus voltage stabilization of the microgrid. A mathematical model of grid-connected converter was established first in this paper, followed by a simulation analysis of the grid-connected converter under direct voltage control. In consideration of the fact that the ideal dynamic voltage response could not be realized by conventional control of the grid-connected converter, a seamless switching control strategy of inhibiting voltage fluctuation was proposed based on the voltage fluctuation analysis of the AC/DC converter, which improved the robust stability of the DC microgrid. The effectiveness and feasibility of the proposed control strategy were verified through the simulation results.


Author(s):  
Feng Zhang ◽  
Xiaolong Guo ◽  
Xiqiang Chang ◽  
Guowei Fan ◽  
Lianger Chen ◽  
...  

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 493 ◽  
Author(s):  
Kumars Rouzbehi ◽  
Arash Miranian ◽  
Juan Manuel Escaño ◽  
Elyas Rakhshani ◽  
Negin Shariati ◽  
...  

This paper develops a data-driven strategy for identification and voltage control for DC-DC power converters. The proposed strategy does not require a pre-defined standard model of the power converters and only relies on power converter measurement data, including sampled output voltage and the duty ratio to identify a valid dynamic model for them over their operating regime. To derive the power converter model from the measurements, a local model network (LMN) is used, which is able to describe converter dynamics through some locally active linear sub-models, individually responsible for representing a particular operating regime of the power converters. Later, a local linear controller is established considering the identified LMN to generate the control signal (i.e., duty ratio) for the power converters. Simulation results for a stand-alone boost converter as well as a bidirectional converter in a test DC microgrid demonstrate merit and satisfactory performance of the proposed data-driven identification and control strategy. Moreover, comparisons to a conventional proportional-integral (PI) controllers demonstrate the merits of the proposed approach.


Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1842 ◽  
Author(s):  
Fuyin Ni ◽  
Zhengming Li ◽  
Qi Wang

In order to improve the functionality and efficiency of a unified power quality conditioner (UPQC), a DC-link bus integrated photovoltaic charging module is proposed in a UPQC. It can generate power for essential loads apart from providing energy to a DC-link bus. A conventional proportional integral (PI) controller fails to run smoothly in dynamic conditions of the micro-grid, since it has poor capabilities in determining suitable values of proportional gain and integral gain. So, the optimization algorithm for a PI controller based on chaos particle swarm optimization based on a multi-agent system (CPSO-MAS) algorithm was developed in this paper to overcome properties such as intermittent instability in the micro-grid. Through verification by simulation and experiment of UPQC harmonic compensation, it showed that the proposed DC link bus voltage control strategy can be effectively applied to UPQC towards various conditions related to voltage and current distortion. In addition, it proved that the proposed strategy has faster convergence than other algorithms, which enhances the stability of DC-link bus voltage. Hence, the contribution presented in this paper is to provide a novel approach for the power quality improvement of UPQC.


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