Power Sharing Control Strategy of High-Frequency Chain Matrix Converter Parallel System Based on Adaptive Virtual Impedance

Abstract In the high frequency link matrix converter parallel system, the impedance parameters on each line are unequal so that the output power of each converter is not equal. To solve this problem, the reason why the power cannot be divided equally under the droop control strategy is analyzed, and a power sharing strategy based on adaptive virtual impedance is proposed. This strategy introduces virtual impedance in a voltage-current dual-loop system with droop control, and uses the converter’s power information and output power factor to adaptively adjust the amplitude and phase of the virtual impedance, so that different branches have the same equivalent output impedance to compensate The voltage drop on the line impedance, while adding the droop control fine-tuning compensation link, so as to realize the load power sharing. Simulation results show that the proposed strategy can effectively improve the accuracy of output power sharing and ensure the stability of the system output voltage amplitude.

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A Droop Control Strategy with Impedance Compensation for Low Voltage Microgrid

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.441.245 ◽

2013 ◽

Vol 441 ◽

pp. 245-248

Author(s):

Zhi Yong Yu ◽

Ming Lu ◽

Zhen Nan Wang ◽

Yi Gong Zhang

Keyword(s):

Control Strategy ◽

Low Voltage ◽

Power Sharing ◽

Droop Control ◽

Parallel Operation ◽

Distributed Generations ◽

Point Of Common Coupling ◽

Simulation Results ◽

Common Coupling ◽

Virtual Impedance

With conventional droop control, parallel operation of distributed generations (DG) in microgrid would lead to unbalanced power sharing. In this paper, inherent limitation of conventional droop control is analyzed. Analysis results show that different converter output impedance and line impedance make the power sharing unbalanced. In order to weaken or eliminate impedance difference from point of common coupling (PCC) to DGs, virtual impedance is introduced. By the introduction of designed virtual impedance, a novel droop control strategy with impedance compensation is proposed in this paper. Simulation results are presented from a two converters parallel-connected microgrid, showing the effectiveness of the droop control with impedance compensation. Simulation results show that DGs with proposed approach can allocate the power equally, and work stably in grid-connected mode, island mode and progress of reconnection to grid.

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Decentralized Virtual Impedance-based Circulating Current Suppression Control for Islanded Microgrids

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.3895 ◽

2021 ◽

Vol 11 (1) ◽

pp. 6734-6739

Author(s):

A. Abu Bakar ◽

E. Pathan ◽

M. K. Khan ◽

M. A. Sadiq ◽

M. I. Rabani ◽

...

Keyword(s):

Power Distribution ◽

Voltage Drop ◽

Impedance Control ◽

Negative Resistance ◽

Power Sharing ◽

Control Technique ◽

Droop Control ◽

Output Impedance ◽

Circulating Current ◽

Virtual Impedance

Parallel connected inverters in islanded mode, are getting momentous attention due to their ability to increase the power distribution and reliability of a power system. When there are different ratings of Distributed Generation (DG) units, they will operate in parallel connection due to different output voltages, impedance mismatch, or different phase that can cause current to flow between DG units. The magnitude of this circulating current sometimes can be very large and damage the DG inverters and also cause power losses that affect power-sharing accuracy, power quality, and the efficiency of the Microgrid (MG) system. Droop control, improved droop control, and virtual impedance control techniques and modifications in the virtual impedance control technique are widely used to suppress the circulating current. However, the addition of the virtual impedance to each inverter to compensate the output impedance is resistive or inductive in nature. The resistive nature of the output impedance always causes a certain voltage drop, whereas the inductive nature of the output impedance causes phase delay for the output voltage. Both problems are addressed by the proposed control mechanism in this paper. Negative resistance, along with virtual impedance, is utilized in the proposed control strategy. The output impedance is to be maintained as inductive in nature to achieve good load sharing in droop control MGs. The simulation results validate the proposed control scheme.

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A Power Sharing Method for Parallel Inverters with Virtual Synchronous Generator Control Strategy

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v4.i2.pp317-324 ◽

2016 ◽

Vol 4 (2) ◽

pp. 317

Author(s):

Sara Yahia Altahir Mohamed ◽

Xiangwu Yan

Keyword(s):

Control Strategy ◽

Reactive Power ◽

Voltage Drop ◽

Synchronous Generator ◽

Power Sharing ◽

System Stability ◽

Droop Control ◽

Active And Reactive Power ◽

Virtual Inertia ◽

Virtual Synchronous Generator

<p>A new power sharing method of a virtual sychronous generator control based inverters is introduced in this paper. Since virtual synchronous generator has virtual inertia and damping properties, it significantly enhances the grid stability. However, its output power considerably affects by the line impedance. Thus, in this paper, the relation between the droop control and the line impedance is analyzed at first. Then, by appling an improved droop control strategy to an inverter based on the virtual sychronous generator control, achieving proportional active and reactive power sharing unaffected by the line impedance is realized. The result shows that a smooth response is achieved. As well as, the voltage drop caused by the line impedance is totally compensated. As a result, the system stability is furtherly improved. At last, the effectiveness of the proposed method is verified through MATLAB/Simulink.</p>

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