A novel control strategy for parallel operation of multi-inverters in low-voltage microgrids

Hu, Xiao; Chen, Dong-Wen; Zhang, Heng; Jia, Dongqiang; Li, Yong; Zhang, Feng

doi:10.1016/j.egyr.2020.11.052

Cited by 6 publications

(4 citation statements)

References 9 publications

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“…MAS is a complex computational system consisting of multiple interacting intelligences, linked together by communication and other means [10]. In this paper, MAS is applied to the control strategy for microgrids, whose control is based on a reliable communication network among DGs, which can be described by graph-theoretic knowledge.…”

Section: Graph Theorymentioning

confidence: 99%

Hierarchical control of island microgrid based on consensus algorithm

Tang,

Wang

2023

J. Phys.: Conf. Ser.

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When the load inside the microgrid changes, droop control maintains a stable power supply cycle of the microgrid by controlling the voltage and frequency at the parallel network of the distributed generation. Since the traditional microgrid droop control usually uses a fixed droop coefficient to adjust the output active power and reactive power, the frequency and voltage of the inverter parallel network will deviate from the system frequency and voltage rating to varying degrees, so a new layer of control link is needed to restore the target value. Moreover, most of the hierarchical control methods adopt centralized control methods, which have limitations such as high dependence on communication. This paper combines a hierarchical control framework and a consistency algorithm to propose a distributed sag control strategy for islanded microgrids based on a multi-agent system. It achieves equal-to-ratio output when distributed generation responds to power changes while maintaining the stability of the microgrid’s main performance indicators. Since the distributed system with a consistency algorithm does not require a centralized control centre, it increases the system’s robustness and reduces the dependence of the system on the communication network. Finally, an islanded AC microgrid model is built by MATLAB/Simulink, and the effectiveness of the proposed islanded microgrid hierarchical control strategy is verified by simulation.

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Section: Graph Theorymentioning

confidence: 99%

Hierarchical control of island microgrid based on consensus algorithm

Tang,

Wang

2023

J. Phys.: Conf. Ser.

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“…The droop control of parallel‐operated VSCs has been mainly studied for the cases in which the power transmission line is dominantly inductive [14]. Also, some applications of droop control in low‐voltage MGs with mainly resistive transmission lines exist in the literature [15, 16].…”

Section: Introductionmentioning

confidence: 99%

VSG‐controlled parallel‐connected voltage‐source converters in low‐voltage microgrid with dominant resistive impedance

Rahimi

2024

The Journal of Engineering

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This paper deals with the control and performance improvement of parallel‐operated voltage‐source inverters (VSIs) controlled as virtual synchronous generators (VSGs). In publications regarding the parallel‐operated VSGs, transmission lines are considered to be mainly inductive. However, less analytical works have been done regarding the control of paralleled VSGs in low‐voltage grids with dominant resistive impedances. Once VSIs are controlled as VSGs in a microgrid with more resistive transmission lines, swing equation and system representation for the power‐angle synchronization will change leading to a new control structure. Therefore, this paper deals with the control of parallel‐operated converter‐based VSGs in low‐voltage grids with dominant resistive line impedances. In this way, the VSG representation, comprising the swing equation and V‐P droop characteristic, for applications in highly resistive microgrids is presented, in which the swing equation and VSG frequency are related to reactive power. Then, the V‐P droop characteristic is modified and an enhanced P‐V droop characteristic for proper sharing of active power between the VSGs in highly resistive microgrids is proposed. Next, the VSG control is modified so that the R/X ratio at the VSG output increases and thus the decoupled control of active/reactive powers in relatively inductive cases is realized as well.

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“…Nowadays, power systems operate together with parallel DG inverters with different line impedances depending upon the inverters' distance from the PCC, as short-, medium-, or long-distance transmission lines can cause power quality issues to the distribution system, especially the circulating current. The reliability of islanded systems is affected by the aforementioned impedance mismatch, as reported in [8][9][10][11][12][13][14][15][16]. The mismatched line impedances of parallel-connected inverters can reverse the current to flow back to the inverter instead of to the load.…”

mentioning

confidence: 99%

Decentralized Virtual Impedance Control for Power Sharing and Voltage Regulation in Islanded Mode with Minimized Circulating Current

Khan,

Zulkifli,

Tutkun

et al. 2024

Electronics

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In islanded operation, precise power sharing is an immensely critical challenge when there are different line impedance values among the different-rated inverters connected to the same electrical network. Issues in power sharing and voltage compensation at the point of common coupling, as well as the reverse circulating current between inverters, are problems in existing control strategies for parallel-connected inverters if mismatched line impedances are not addressed. Therefore, this study aims to develop an improved decentralized controller for good power sharing with voltage compensation using the predictive control scheme and circulating current minimization between the inverters’ current flow. The controller was developed based on adaptive virtual impedance (AVI) control, combined with finite control set–model predictive control (FCS-MPC). The AVI was used for the generation of reference voltage, which responded to the parameters from the virtual impedance loop control to be the input to the FCS-MPC for a faster tracking response and to have minimum tracking error for better pulse-width modulation generation in the space-vector form. As a result, the circulating current was maintained at below 5% and the inverters were able to share an equal power based on the load required. At the end, the performance of the AVI-based control scheme was compared with those of the conventional and static-virtual-impedance-based methods, which have also been tested in simulation using MATLAB/Simulink software 2021a version. The comparison results show that the AVI FCS MPC give 5% error compared to SVI at 10% and conventional PI at 20%, in which AVI is able to minimize the circulating current when mismatch impedance is applied to the DGs.

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A novel control strategy for parallel operation of multi-inverters in low-voltage microgrids

Cited by 6 publications

References 9 publications

Hierarchical control of island microgrid based on consensus algorithm

Hierarchical control of island microgrid based on consensus algorithm

VSG‐controlled parallel‐connected voltage‐source converters in low‐voltage microgrid with dominant resistive impedance

Decentralized Virtual Impedance Control for Power Sharing and Voltage Regulation in Islanded Mode with Minimized Circulating Current

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