A Multi-Stage Pre-Synchronization Strategy For Smooth Grid Connection Of DVOC-Based Grid-Forming Inverters

Bahri, Zuhri Muhammad (2026) A Multi-Stage Pre-Synchronization Strategy For Smooth Grid Connection Of DVOC-Based Grid-Forming Inverters. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Grid-forming (GFM) inverters using Dispatchable Virtual Oscillator Control (dVOC) require a reliable pre-synchronization process before grid connection to prevent terminal voltage drops and reactive power transients. Conventional passive synchronization methods treat the inverter as an unforced black box and rely on the natural drift of the reference signal to achieve synchronization. However, this approach results in long connection delays when large initial mismatches are present. Directly injecting active tracking errors into the oscillator accelerates phase synchronization but may cause a sudden power sink that reduces the terminal root-mean-square (RMS) voltage below the predefined safe limit (VPCC < 0.985 × Vgrid). To address this trade-off, this study proposes a Multi-Stage Pre-Synchronization sequence combined with an error-dependent piecewise nonlinear inverse decay ramp applied exclusively to the oscillator’s α-axis input. To efficiently determine the optimal ramp gain parameters without time-consuming trial-and-error simulations, a data-driven optimization framework is introduced. By freeze-locking the parameters of a trained Multilayer Perceptron (MLP) surrogate network (∇WL = 0), the framework employs Stochastic Gradient Descent (SGD), Automatic Differentiation (AD), and the Sequential Unconstrained Minimization Technique (SUMT) with a barrier method to determine the optimal ramp gain directly from the model equations. Continuous simulation results demonstrate that the proposed method maintains voltage drops within acceptable limits while significantly reducing grid connection time compared with conventional passive drift synchronization methods.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Grid-Forming Inverters, Virtual Oscillator Control, Pre-Synchronization, Surrogate Modeling, Constraint Optimization
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK1007 Electric power systems control
Divisions:	Faculty of Electrical Technology > Electrical Engineering > 20201-(S1) Undergraduate Thesis
Depositing User:	Zuhri Muhammad Bahri
Date Deposited:	31 Jul 2026 06:14
Last Modified:	31 Jul 2026 06:14
URI:	http://repository.its.ac.id/id/eprint/140850

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