Self-Synchronization Scheme for Network of Grid-following and Grid-forming Photovoltaic Inverters

Gupta, Shantanu; Umar, Muhammad Farooq; Shadmand, Mohammad B.; Mazumder, Sudip K.

doi:10.1109/iecon48115.2021.9589752

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…GFIs are an advanced type of inverter used in power systems to provide stable and reliable power to the grid [42], [43]. Unlike grid-supporting and gridfollowing inverters to follow the voltage and frequency of the main grid, grid-forming inverters can control the voltage and frequency of islanded microgrids [29], [44]. It means GFIs can operate independently of the grid and maintain stability and reliability [45], [46], [47], [48], [49], [50].…”

Section: Introductionmentioning

confidence: 99%

“…The parallel operation of GFIs involves coordinating multiple inverters to operate in synchronization, ensuring a smooth transition between different operating modes and enabling power sharing between different GFIs [44], [49], [56]. Many methods have been proposed in the literature for synchronization systems.…”

Section: Introductionmentioning

confidence: 99%

“…This study investigates the nonlinearity caused by the initial condition dependency and the cross-coupling effect. In addition, commissioning problems are considered after the synchronization loops are completed [44], [55], [58], [72], [78]. In parallel operation, GFIs can first be synchronized under loading conditions [9], [27], [79].…”

Section: Introductionmentioning

confidence: 99%

“…Different methods for commissioning microgrid inverters have been proposed in the literature, such as soft-start, soft-commissioning, and black start [43], [44], [96], [97], [98], [99]. However, special control methods are needed after synchronization to commission the inverters in islanded microgrids.…”

Section: Introductionmentioning

confidence: 99%

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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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