An iterative adaptive virtual impedance loop for reactive power sharing in islanded meshed microgrids

Sellamna, H.; Pavan, Alessandro; Mellit, A.; Guerrero, Josep M.

doi:10.1016/j.segan.2020.100395

Cited by 17 publications

(6 citation statements)

References 28 publications

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“…By solving the obtained formulas, the reactive power sharing error (∆Q) due to the mismatched components of feeder 1 and feeder 2 is derived as [20], [21]…”

Section: B Reactive Power Sharing Considering Mismatched Feeder Imped...mentioning

confidence: 99%

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Accurate Reactive Power Sharing Strategy for Droop-Based Islanded AC Microgrids

Mohammed

Lashab

Ciobotaru

et al. 2023

IEEE Trans. Ind. Electron.

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In islanded AC microgrids, the mismatched impedances of the interfacing feeders between the inverters and the load bus cause poor reactive power sharing when the conventional frequency and voltage droop control technique is employed. Such operation endangers the whole microgrid reliability as it may lead to overloading certain inverters and, consequently, triggering protection relays and causing cascaded failure. Thus, this paper proposes an accurate reactive power sharing strategy that considers the mismatched feeder impedances in islanded AC microgrids. It is based on the optimal tuning of the virtual complex impedance for each inverter. The proposed strategy has several advantages. First, it has a physical meaning as it establishes an explicit relationship between the mismatched values of the actual resistive-inductive feeders and the assigned values for the proposed virtual complex impedance to each inverter. Hence, further degradations in the microgrid voltages are prevented. Second, there is no need for prior knowledge about the actual feeder impedances in the design stage as they are estimated online from the available measurements. Lastly, the proposed control is reliable and fault-tolerant as it copes with unexpected failures such as failure of (or sudden switching off)some inverters and communication disruptions/delays. It ensures accurate power sharing even under the primary controllers after losing communication links with the secondary controller. The simulation and experimental verification results are presented to validate the performance of the proposed technique.

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“…By solving the obtained formulas, the reactive power sharing error (∆Q) due to the mismatched components of feeder 1 and feeder 2 is derived as [20], [21]…”

Section: B Reactive Power Sharing Considering Mismatched Feeder Imped...mentioning

confidence: 99%

“…It is used to obtain both the alpha and beta components of the output current of the j th inverter. The SOGI closed-loop transfer functions for alpha and beta channels are given by ( 20) and (21), respectively [29].…”

Section: Stability Analysismentioning

confidence: 99%

Accurate Reactive Power Sharing Strategy for Droop-Based Islanded AC Microgrids

Mohammed

Lashab

Ciobotaru

et al. 2023

IEEE Trans. Ind. Electron.

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“…Networked MG This method modifies the conventional droop equations by partial transient active-reactive power-coupling method. Sellamna et al (2020) 2020…”

Section: Parallel Dgs With Common Loadmentioning

confidence: 99%

“…Yet, this method requires communication links for synchronization. Sellamna et al (2020) introduced a tuned adaptive virtual impedance with local parameters to adjust the virtual impedance continuously until no change in reactive power sharing was achieved. Gupta et al (2020) proposed an improved reactive power-sharing scheme by calculation an adaptive Q − V droop coefficient after each load change.…”

Section: Introductionmentioning

confidence: 99%

Communicationless Adaptive Control Strategy for Effective Reactive Power Sharing in a Grid-Independent AC Microgrid

Suchitra¹,

Anitha²,

S³

et al. 2022

Front. Energy Res.

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The microgrid (MG) ensures a reliable power supply as it can work in a grid-independent mode. This mode requires a coordinated control strategy among distributed generators (DGs). One major challenge in a grid-independent MG is the reactive power-sharing issue. The reactive power sharing is affected by the mismatch of feeder impedance and private loads. This study thus proposed a proportionate reactive power-sharing scheme in a grid-independent mode by mathematically computing the equivalent impedance without the need for communication lines. A mathematical formula is derived to compute the equivalent impedance as a function of the total power output of DG and the power fed to the feeder. Based on the computed equivalent impedance, the virtual impedance is added to each feeder. The inclusion of virtual impedance in each line compensates the mismatch in feeder impedance and private loads providing accurate reactive power sharing among DGs. MATLAB Simulink was used to verify the effectiveness of the proposed control strategy. Furthermore, the real-time OPAL-RT simulator was used to verify the results.

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“…Microgrids must be connected to the main grid or operate in parallel with other microgrids to increase the installed power [12], [13], [14]. The synchronization of an islanded microgrid to the main power grid is important [15], [16], [17], [18].…”

Section: Introductionmentioning

confidence: 99%

Frequency, Phase, and Magnitude Difference Locked-Loop Based Linear Synchronization Scheme for Islanded Inverters and Microgrids

Atmaca

Karabacak

2023

IEEE Access

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In recent years, integrating renewable energy sources (RESs) has achieved significant attention due to the growing demand for sustainable energy solutions. Inverter-interfaced Islanded Microgrids (IGs) have appeared as an advantageous approach to integrating RESs into the power grid. Grid-forming inverters (GFIs) are a critical component of IGs, and their synchronization is essential for stable and reliable operation. The literature has widely proposed soft transition, pre-synchronization, and re-synchronization to synchronize IGs to the main grid. However, methods for synchronizing GFIs in the islanded microgrid are restricted. Parallel operation of GFIs is required to guarantee the high-power demand of IG and improve voltage-frequency stability. For parallel operation, GFIs must be synchronized with each other. In the conventional synchronization control systems that are highly nonlinear, the linear proportional-integral (PI) controllers are commonly used in synchronization loops without considering the nonlinearity resulting from the initial condition dependency and cross-coupling. Thus, conventional synchronization methods can be exposed to concerns of stable operation, narrow operation area, and performance degradation. This study proposes a new linearized synchronization control system for GFIs in IGs. In this way, it is possible to analytically design robust linear controllers and ensure a stable operation, high performance, and wide (full) operation area. In addition, a new soft-commissioning method is proposed to deactivate synchronization loops and soft-start the synced GFI. The proposed system has been tested in real-time and CHIL hardware setups for two 550 kW GFIs operating in parallel, and the results in the perfect agreement are presented in this study.INDEX TERMS Commissioning, control hardware-in-the-loop (CHIL), grid-forming inverter, islanded microgrid, load sharing, microgrid, synchronization.

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An iterative adaptive virtual impedance loop for reactive power sharing in islanded meshed microgrids

Cited by 17 publications

References 28 publications

Accurate Reactive Power Sharing Strategy for Droop-Based Islanded AC Microgrids

Accurate Reactive Power Sharing Strategy for Droop-Based Islanded AC Microgrids

Communicationless Adaptive Control Strategy for Effective Reactive Power Sharing in a Grid-Independent AC Microgrid

Frequency, Phase, and Magnitude Difference Locked-Loop Based Linear Synchronization Scheme for Islanded Inverters and Microgrids

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