An Improved Proportional Load-Sharing Strategy for Meshed Parallel Inverters System With Complex Impedances

The communication link, low reliability, inaccurate power sharing and voltage and frequency deviations are some challenges in control methods of parallel inverters in high voltage microgrids. This paper proposes a hybrid control method using the impedancepower droop and conventional droop methods. In the proposed hybrid method, the impedance-power droop method works as the main strategy in steady state and the conventional droop method is employed as auxiliary strategy during startup and transient states. The notable advantages of the proposed method are low virtual impedances, no need for recognition of system parameters, simple and low calculations. Moreover, the voltage deviation in the steady state is minimized and the frequency deviation is completely eliminated. Finally, the performance of the control method is validated by simulation.

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“…The voltage and frequency droop characteristics in an inductive islanded microgrid are given by equation (1):…”

Section: Conventional Droop Methodsmentioning

confidence: 99%

“…In recent years, the operation of parallel inverters has expanded dramatically [1], [2]. In parallel operation, the inverters should be controlled in order to avoid overloading and maintain good power quality requirements [3].…”

Section: Introductionmentioning

confidence: 99%

Robust hybrid control of parallel inverters for accurate power-sharing in microgrid

Razi

Pham

Hably

et al. 2020

2020 IEEE International Conference on Industrial Technology (ICIT)

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“…In addition, the computation time for the optimisation process and the communication delay are not discussed. The method presented in [25] relies on the communication link as the MGCC is responsible for coordinating DG units for accurate reactive power sharing by means of sending corresponding signals.…”

Section: Compromising Between Power Sharing and Power Qualitymentioning

confidence: 99%

Microgrid operation improvement by adaptive virtual impedance

Eskandari

2018

IET Renewable Power Generation

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Microgrid concept (MG) is regarded as the best solution for optimal integration of the renewable energy sources (RESs) into power systems. However, novel control strategies should be developed because of the distinct inherent feature of MG components in comparison to conventional power systems. Although the droop-based control method is adopted in the MG to share power among distributed generation units, its dependency to grid parameters makes its implementation not as convenient as that in conventional power systems. Virtual impedance has been proposed as the complementary part of droop control in MGs. In this paper, adaptive virtual impedance is designed considering its effects on the system performance in the MG including: 1) Decoupling active and reactive power control by making the grid X/R ratio high, 2) Maximum transferable power through the feeder, 3) Stability concern, 4) Precise reactive power sharing in different operating modes as well as smooth transition from connected mode (CM) to islanded mode (IM). To this end, a novel method is proposed to determine the reactive power reference of distributed generation (DG) units according to their contribution in reactive power sharing in IM. In addition, simulation in MATLAB/SIMULINK environment is conducted to assess the performance of the control system.

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“…The −90 • phase shift in i ox is required, and p x , q x are filtered by low-pass filters (LPFs) to achieve the average active power P x and reactive power Q x . The LPF is given by (6), where the cutoff angle frequency ω c is set to 314 rad/s.…”

Section: Calculation Of Average Powermentioning

confidence: 99%

“…The microgrid can operate not only in the grid-connected mode, but also in the islanded mode, providing more reliable power to critical loads [4,5]. In the islanded microgrid, most studies focus on parallel-inverter power sharing [6,7] and circulation restraint [8], power management for all kinds of DGs and types of energy storage [9,10], and compensation for voltage unbalance [3,[11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

A Compensation Control Scheme of Voltage Unbalance Using a Combined Three-Phase Inverter in an Islanded Microgrid

et al. 2018

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A large number of single-phase loads in an islanded microgrid have a bad influence on the alternating current (AC) bus voltage symmetry, which will further impact the power supply for the other loads. In this paper, the combined three-phase inverter is adopted as the distributed generation (DG) interface circuit for its independent control of each bridge. However, the combined three-phase inverter will generate an asymmetrical voltage with the traditional droop control. Moreover, the system impedance also effects the voltage symmetry. Therefore, the improved droop control method based on the self-adjusting P-f and Q-U droop curves and the system impedance voltage drop compensation are proposed. The system control scheme is also designed in detail. A simulation and an experiment under the conditions of the balanced, unbalanced loads are carried out, and the results verify the feasibility and effectiveness of the control strategy.

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An Improved Proportional Load-Sharing Strategy for Meshed Parallel Inverters System With Complex Impedances

Cited by 46 publications

References 29 publications

Robust hybrid control of parallel inverters for accurate power-sharing in microgrid

Robust hybrid control of parallel inverters for accurate power-sharing in microgrid

Microgrid operation improvement by adaptive virtual impedance

A Compensation Control Scheme of Voltage Unbalance Using a Combined Three-Phase Inverter in an Islanded Microgrid

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