Reactive Power Sharing in Islanded Microgrid by Using Voltage Recovery Operation of Droop Control Strategy

<a name="_Hlk16093850"></a><span>Droop control technique is one of the renowned techniques which does not need any communication connection between Distibuted Generations (DG), hence the cost, as well as the reliability of the microgrid (MG) system can be reduced. MG is operated in two modes as their functionality and structure is concern. These are the grid connected or islanded (stand-alone) mode. DGs operating values may have different ratings of voltage, power and line impedance. The power sharing in these operatng conditions is not shared equally by all DGs connected in the system and also during load changes conditions power sharing accuracy is difficult to achieve. In this paper, a droop power control is used to balance the power sharing in islanded mode. As from the results, the active power sharing is equally shared from all DGs connected in the microgrid system. However, reactive power sharing accuracy always disturbed when there is impedance mismatch among the different DG feeders. The accuracy is done by monitoring the effects when load changes for low load to high load or vice versa. The Proportional Integral (PI) controller has been used to minimize the reactive power errors. At the end, the power droop is capable to share power accurately and results prove the stability and reliability of the proposed technique.</span>

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A New Adaptive Control Strategy of active and reactive power sharing in Islanded Microgrids

Science and Technology Development Journal ◽

10.32508/stdj.v19i4.779 ◽

2016 ◽

Vol 19 (4) ◽

pp. 14-34

Author(s):

Phuong Minh Le ◽

Duy Vo Duc Hoang ◽

Hoa Thi Xuan Pham ◽

Huy Minh Nguyen ◽

Dieu Ngoc Vo

Keyword(s):

Transmission Line ◽

Distributed Generation ◽

Reactive Power ◽

Active Power ◽

Power Sharing ◽

Droop Control ◽

Active And Reactive Power ◽

Three Phase ◽

Islanded Microgrid ◽

Adaptive Control Strategy

This paper proposes a new control sharing method for parallel three-phase inverters in an islanded microgrid. The proposed technique uses adaptive PIDs combined with the communication among the parallel inverters to accurately share active power and reactive power among the inverters via adjusting the desired voltage if there is a distinct difference between line impedance and the load change in the microgrid. Moreover, the paper also presents the response ability of the inverters to maintain the error within the allowed limits as the transmission line is interrupted. The proposed technique has been verified in a microgrid with three parallel distributed generation-inverter units using Matlab/Simulink. In the simulation, as the droop control using the communication information among the inverters, the sharing errors for active power and reactive power are around 0.2% and 0.6%, respectively. As the connection between the microgrid and transmission line is interrupted, the sharing errors for active power and reactive power increase to 0.4% and 2%, respectively. The simulation results have indicated that the proposed technique is superior to the traditional droop control in terms of the accuracy and stability. Therefore, the new proposed technique can be a favor alternative model for active power and reactive power sharing control of parallel inverters in an islanded microgrid.

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A Reactive Power-Voltage Control Strategy of an AC Microgrid Based on Adaptive Virtual Impedance

Energies ◽

10.3390/en12163057 ◽

2019 ◽

Vol 12 (16) ◽

pp. 3057

Author(s):

Yao Liu ◽

Lin Guan ◽

Fang Guo ◽

Jianping Zheng ◽

Jianfu Chen ◽

...

Keyword(s):

Distributed Generation ◽

Control Strategy ◽

Reactive Power ◽

Reference Value ◽

Voltage Control ◽

Power Sharing ◽

Voltage Reference ◽

Voltage Control Strategy ◽

Voltage Recovery ◽

Virtual Impedance

As an effective carrier of distributed generation, a microgrid is an effective way to ensure that distributed power can be reasonably utilized. However, due to the property of line impedance and other factors in a microgrid, reactive power supplied by distributed generation units cannot be shared rationally. To efficiently improve reactive power sharing, this paper proposes a reactive power-voltage control strategy based on adaptive virtual impedance. This method changes the voltage reference value by adding an adaptive term based on the traditional virtual impedance. Meanwhile, a voltage recovery mechanism was used to compensate the decline of distributed generation (DG) output voltage in the process. MATLAB/Simulink simulations and experimental results show that the proposed controller can effectively improve the steady state performance of the active and reactive power sharing. Finally, the feasibility and effectiveness of the proposed control strategy were verified.

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