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

Ren, Biying; Sun, Xiaodong; Chen, Shasha; Liu, Huan

doi:10.3390/en11092486

Cited by 17 publications

(12 citation statements)

References 24 publications

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“…The parallelization of single-phase inverters without communications between them has usually been performed using the droop method, which drives the sinusoidal references of the inverters for sharing the common loads [1][2][3]. The method introduces proportional droops in the inverter frequency ω* and voltage amplitude V* references, respectively, according to the P and Q load consumed powers.…”

Section: Introductionmentioning

confidence: 99%

A Power Calculation Algorithm for Single-Phase Droop-Operated-Inverters Considering Linear and Nonlinear Loads HIL-Assessed

et al. 2019

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The active and reactive powers, P and Q, are crucial variables in the parallel operation of single-phase inverters using the droop method, introducing proportional droops in the inverter output frequency and voltage amplitude references. P and Q, or P-Q, are calculated as the product of the inverter output voltage and its orthogonal version with the output current, respectively. However, when sharing nonlinear loads these powers, Pav and Qav, should be averaged by low-pass filters (LPFs) with a very low cut-off frequency to avoid the high distortion induced by these loads. This forces the droop method to operate at a very low dynamic velocity and degrades the system stability. Then, different solutions have been proposed in literature to increase the system velocity, but only considering linear loads. Therefore, this work presents a method to calculate Pav and Qav using second-order generalized integrators (SOGI) to face this problem with nonlinear loads. A double SOGI (DSOGI) approach is applied to filter the nonlinear load current and provide its fundamental component to the inverter, leading to a faster dynamic velocity of the droop-based load sharing capability and improving the stability. The proposed method is shown to be faster than others in the literature when considering nonlinear loads, while smoothly driving the system with low distortion levels. Simulations, hardware-in-loop (HIL) and experimental results are provided to validate this proposal.

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Section: Introductionmentioning

confidence: 99%

A Power Calculation Algorithm for Single-Phase Droop-Operated-Inverters Considering Linear and Nonlinear Loads HIL-Assessed

et al. 2019

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“…To avoid the estimation of impedance, voltage compensation-based approach for accurate load sharing is proposed in [32] which can compensate the load effect alone. Recently, a compensatory approach through self-adjustment of droop gains for islanded microgrid application also suggest the same [33]. A robust droop control method proposed in [34,35] contributes proportionate power sharing and voltage regulation by adjusting droop gain, termed as amplification correction factor.…”

Section: Introductionmentioning

confidence: 94%

Reinforced Droop for Active Current Sharing in Parallel NPC Inverter for Islanded AC Microgrid Application

Purushotham

Muniswamy

2019

Energies

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The paper investigates the current sharing in parallel 3-level Neutral point clamped inverter for islanded AC microgrid application. In Distributed generation, parallel power electronic interface based microgrid suffers from power quality issues due to inaccurate output current sharing. To address the current sharing problem, the paper proposes an improved droop technique that reinforces the droop loop by infusing the incurred voltage drop accountable for inaccurate current sharing at the inverter output. The control based on droop reference is bounded with regard to output current since the output impedance influences the output current of the inverter largely. Besides that, the parallel NPC inverter also suffers from dc link voltage imbalance due to neutral currents. To address these issues a control strategy is proposed in the research work in which the processed DC offset is incorporated into the reinforced droop loop and the generated reference is utilized with feedback control to accurately share the currents under linear and nonlinear load conditions. The effectiveness of devised reinforced droop strategy is realized in MATLAB/Simulink environment and experimental validation is carried out with the field-programmable gate array as hardware interface to the hardware laboratory prototype of parallel NPC inverter.

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“…In an islanded microgrid that operates under unbalanced conditions, the asymmetric inverter output voltages could affect the droop control strategies. The droop control scheme has been adapted in [100] to obtain symmetrical three-phase reference voltage signals. The sharing of positive-, negative-and zero-sequence currents in islanded low voltage microgrids operating in unbalanced conditions has been addressed in [101] with the addition of virtual negative-sequence and zero-sequence impedance controllers.…”

Section: Distribution Systems With Distributed Energy Resourcesmentioning

confidence: 99%

100 Years of Symmetrical Components

Chicco

Mazza

2019

Energies

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28 June 2018 was the 100th anniversary of the first presentation on symmetrical components made by Charles LeGeyt Fortescue at the 34th Annual Convention of the American Institute of the Electrical Engineers in Atlantic City (NJ, USA). The introduction of the symmetrical component concept was immediately seen as a milestone for electrical system studies, and many applications have been developed during the ensuing years. Today, refined or advanced contributions to conceptual and practical aspects of electrical applications are still being proposed based on the powerful structure of symmetrical components. This paper recalls the most significant steps made in the electrical engineering field after the introduction of the symmetrical component theory, and indicates recent developments concerning the studies on electrical machines, harmonics and interharmonics in different applications, and the operation of power and distribution systems with distributed energy resources.

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

Cited by 17 publications

References 24 publications

A Power Calculation Algorithm for Single-Phase Droop-Operated-Inverters Considering Linear and Nonlinear Loads HIL-Assessed

A Power Calculation Algorithm for Single-Phase Droop-Operated-Inverters Considering Linear and Nonlinear Loads HIL-Assessed

Reinforced Droop for Active Current Sharing in Parallel NPC Inverter for Islanded AC Microgrid Application

100 Years of Symmetrical Components

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