Structural Improvements in Consensus-Based Cooperative Control of DC Microgrids
Abstract
:1. Introduction
1.1. Motivation
1.2. Literature Review
1.3. Contributions
- Finite-gain voltage controller is introduced in the outer voltage loop with a simple proportional (P) controller in the inner current control loop. In this way, droop-like performance can be ensured without droop control.
- A different method is adopted in the consensus-based cooperative control to estimate the average voltage and current difference. Proportional current sharing and DC voltage restoration can be guaranteed by updating the single voltage correction term of the consensus control layer.
- The proposed control technique does not require prior knowledge of the nodes, so the proposed technique is scalable and has plug-and-play capability.
- A sparse communication network spans across the DC microgrid, due to which neighbors can interact with each other. This is different from the centralized technique.
- In order to ensure a good bandwidth and better control performance, the impact of communication delay is considered and analyzed. The voltage control loop bandwidth is also considered with the increasing number of nodes.
- In the presence of disturbance, the convergence time (disturbance rejection time) of the proposed controller is compared with the conventional power-sharing techniques.
2. Overview of Existing Techniques
2.1. Conventional Droop-Control-Based Technique
2.1.1. Local Controller
2.1.2. Cooperative Controller
2.2. Conventional Droop-less Technique
Local Controller
2.3. Limitations of the Existing Techniques
3. Proposed Technique
3.1. Proposed Local Controller
3.2. Cooperative Control Structure
4. Small Signal Analysis
5. Communication Network Overview and Graph Theory
Communication Delay Impact on System Performance
6. Simulation Results and Discussion
7. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Power-Sharing Techniques | Stability | Disturbance Rejection Time | Current-Sharing Accuracy | Voltage Regulation | Viability |
---|---|---|---|---|---|
Conventional droop-based technique [12] | Low | High | High | High | Low |
Improved cooperative control technique [13] | Medium | Medium | High | Medium | Medium |
Proposed technique | High | Low | High | High | High |
Communication Delay | Existing Technique [12], Voltage Control Bandwidth | Existing Technique [13], Voltage Control Bandwidth | Proposed Technique, Voltage Control Bandwidth |
---|---|---|---|
0.1 ms | 0.507 kHz | 0.528 kHz | 0.550 kHz |
0.05 ms | 0.520 kHz | 0.540 kHz | 0.562 kHz |
0.33 ms | 0.525 kHz | 0.546 kHz | 0.568 kHz |
0.40 ms | 0.528 kHz | 0.548 kHz | 0.570 kHz |
Number of nodes | Bandwidth with increasing nodes | Bandwidth with increasing nodes | Bandwidth with increasing nodes |
5 | 0.520 kHz | 0.540 kHz | 0.562 kHz |
10 | 0.270 kHz | 0.295 kHz | 0.320 kHz |
20 | 0.145 Hz | 0.170 kHz | 0.205 kHz |
Parameters | Existing Technique [12] | Existing Technique [13] | Proposed Technique | |
---|---|---|---|---|
PV/Wind | Vg | 600 V | 600 V | 600 V |
Reference voltage | Vref | 400 V | 400 V | 400 V |
DC/DC Buck converter | L | 2.5 mH | 2.5 mH | 2.5 mH |
C | 220 μF | 220 μF | 220 μF | |
Inner loop | kp | 0.1 | 0.1 | 0.09 |
ks | 0.5 | 0.5 | — | |
Outer loop | kp | 0.05 | 0.2 | — |
ks | 10 | — | — | |
z | — | — | 0.045 | |
p | — | — | 0.0045 | |
Droop gain | Gd | 0.025 | — | — |
Distributed cooperative control | kpc,v | 1.7 | 10 | 25 |
ksc,v | 15 | 200 | 150 | |
kpc,i | 1.5 | — | — | |
ksc,i | 2.5 | — | — |
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Mumtaz, M.A.; Khan, M.M.; Fang, X.; Shahid, M.U.; Faiz, M.T. Structural Improvements in Consensus-Based Cooperative Control of DC Microgrids. Electronics 2019, 8, 187. https://doi.org/10.3390/electronics8020187
Mumtaz MA, Khan MM, Fang X, Shahid MU, Faiz MT. Structural Improvements in Consensus-Based Cooperative Control of DC Microgrids. Electronics. 2019; 8(2):187. https://doi.org/10.3390/electronics8020187
Chicago/Turabian StyleMumtaz, Muhammad Adnan, Muhammad Mansoor Khan, Xiangzhong Fang, Muhammad Umair Shahid, and Muhammad Talib Faiz. 2019. "Structural Improvements in Consensus-Based Cooperative Control of DC Microgrids" Electronics 8, no. 2: 187. https://doi.org/10.3390/electronics8020187
APA StyleMumtaz, M. A., Khan, M. M., Fang, X., Shahid, M. U., & Faiz, M. T. (2019). Structural Improvements in Consensus-Based Cooperative Control of DC Microgrids. Electronics, 8(2), 187. https://doi.org/10.3390/electronics8020187