Control strategy for parallel-connected three-phase inverters

Biel, Zdeno; Jeck, Peter; Ilonciak, Jaroslav; Valco, Marek

doi:10.1109/elektro.2018.8398283

Cited by 4 publications

(6 citation statements)

References 6 publications

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“…In MGs, it is mostly used conventional synchronization systems based on droop control [19], [21], [23], [91], [92]. The droop control-based phase synchronization loop equation is given in (1).…”

Section: A the First Nonlinearity Caused By The Initial Value Depende...mentioning

confidence: 99%

“…Fig. 2 provides the PSL for the conventional synchronization system, which is seen to be integrated with the P/f droop control loop [19], [21], [23], [91], [92]. In Fig.…”

Section: A the First Nonlinearity Caused By The Initial Value Depende...mentioning

confidence: 99%

“…As seen from ( 3), the equation is highly nonlinear due to both (ω 1 − ω s ) t and the sine function. So, linear controllers such as PI may not stabilize nonlinear PSL [9], [27], [57], [91], [93], [162]. In addition, a limited range in between ±1 rad is the case for the conventional synchronization method, accordingly, error signal, e qc , oscillates between the limits of ±1 rad under large-signal transients [104], [105].…”

Section: A the First Nonlinearity Caused By The Initial Value Depende...mentioning

confidence: 99%

“…Furthermore, all those studies use linear Proportional-Integral (PI) controllers in PSL and VSL, ignoring this nonlinearity [10], [74], [86], [91], [92]. It is a well-known fact in literature; it is not possible for linear controllers used in nonlinear systems to be analytically designed, and the resulting control system is always subject to stability and performance issues [93], [94], [95].…”

Section: Introductionmentioning

confidence: 99%

“…It is a well-known fact in literature; it is not possible for linear controllers used in nonlinear systems to be analytically designed, and the resulting control system is always subject to stability and performance issues [93], [94], [95]. In studies published in the literature [10], [19], [20], [21], [22], [23], [57], [74], [86], [91], [92] no paper presents a solution coping with the nonlinearity mentioned above.…”

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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Section: A the First Nonlinearity Caused By The Initial Value Depende...mentioning

confidence: 99%

“…Fig. 2 provides the PSL for the conventional synchronization system, which is seen to be integrated with the P/f droop control loop [19], [21], [23], [91], [92]. In Fig.…”

Section: A the First Nonlinearity Caused By The Initial Value Depende...mentioning

confidence: 99%