Keywords
hierarchical control
islanded mode
voltage unbalance
line impedance мікроенергосистема
ієрархічний контроль
ізольований режим
дисбаланс напруги
повний вхідний опір лінії
How to Cite
Abstract
When the microgrid is running in an islanded mode, unbalanced loads result in microgrid voltage unbalance. The voltage unbalance factor at the Point of Common Coupling (PCC) is a key parameter in measurement of microgrid power quality. To improve microgrid power quality, many documents utilize micro-source voltage measurement results to help adjust the unbalance factor of microgrid voltage. However, due to line impedance presence, there are differences between micro-source output voltage and PCC voltage. Therefore, it is impossible for a micro-source to control the unbalance factor of PCC voltage with high precision by measuring its own output voltage. Based on equivalent circuit, the present paper analyzes the negative sequence component relationship among micro-source output voltage, line impedance voltage drop, and PCC voltage. It further proposes a hierarchical-control-based method to control the unbalance factor of PCC voltage with high accuracy, and analyzes the impact of secondary control delay on system stability by root locus calculating. Finally, the control strategy is validated in an islanded microgrid system with two micro-sources. The experimental results show the effectiveness and feasibility of the proposed control strategy. References 8, figures 7.
References
Guerrero J.M., de Vicuna L.G., Matas J., et al. A wireless controller in distributed generation system // IEEE Transactions on Power Electronics. – 2004. – No 5. – Pp. 1205-1213.
Guerrero J.M., Vasquez J.C., Matas J., et al. Hierchical control of droop-controlled AC and DC microgrid: a general approach toward standardization // IEEE Transactions on Industrial Electronics. – 2011. – No1. – Pp. 158-172.
Guerrero J.M., Garciade Vicuna L., Matas J., et al. Outout impedance design of parallel-connected UPS inverters with wireless load-sharing control // IEEE Transactions on Industrial Electronics. – 2005. – No 4. – Pp. 1126-1135.
Hamzeh M., Karimi H., Mokhtari H. Harmonic and Negative-Sequence Current Control in an Islanded Multi-Bus MV Microgrid // IEEE Transactions on Smart Grid. – 2014. – No1. – Pp. 167-176.
Jin W.H., Yun W.L., Munir M.S. A Flexible Harmonic Control Approach Through Voltage-Controlled DG-Grid Interfacing Converters // IEEE Transactions on Industrial Electronics. – 2012. – No1. – Pp. 444-455.
Lassetter R., Akhil A., Marnay C., et al. Integration of distributed energy resources: the CERTS microgrid concept. – Berkeley, CA, USA: Consortium for Electric Reliability Technology Solutions. – 2002 p.
Xion F.W., Frede B., Zhe C. Autonomous Control of Inverter-Interfaced Distributed Generation Units for Harmonic Current Filtering and Resonance Damping in an Islanded Microgrid // IEEE Transactions on Industry Applications. – 2014. – No1. – Pp. 452-461.
Zeineldin H.H., El-Saadany E.F., Salama M.A. Distributed Generation Micro-Grid Operation: Control and Protection // Power Systems Conference 2006: Advanced Metering, Protection, Control, Communication and Distributed Resources. – 2006. – Pp. 105-111.
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