Islanding occurs when a connected load to the grid is disconnected from the grid and energized solely by local generators. Islanding can result in frequency and voltage instability, changes in current, and overall poor power quality. Poor power quality can interrupt industrial operations, damage sensitive electrical equipment, and induce outages upon the resynchronization of the island with the grid. This study proposes an islanding detection method employing Duffing oscillators to analyze fluctuations at the point of common coupling (PCC) under a high-noise environment, focusing on decreasing detection period, zero power mismatch nondetection zone, and power quality degradation. Unlike existing methods, which overlook the noise effect, this study mitigates noise impact on islanding detection. Power system noise in PCC measurements arises from switching transients, harmonics, grounding issues, voltage sags, voltage swells, electromagnetic interference, and power quality issues that affect islanding detection. Transient events, like lightning-induced traveling waves can also introduce noise levels exceeding the voltage amplitude, disturbing conventional detection techniques~cite{IEEE1313}. The noise interferes with measurements and increases the nondetection zone (NDZ), causing failed or delayed islanding detection. Duffing oscillator nonlinear dynamics enable detection capabilities at a high noise level. The proposed methods are designed to detect the PCC measurement fluctuations based on the IEEE standard 1547 through the Duffing oscillator. The basic idea is that the Duffing oscillator phase trajectory changes from periodic to chaotic mode and sends an islanded operation command to the inverter. The proposed islanding detection method can distinguish switching transients and faults from an islanded operation. / Master of Science / This study introduces a method to detect one of the important power grid issues, called islanding. Islanding occurs when a power grid section becomes isolated and continues to operate independently, leading to power quality problems and safety hazards. The method is developed using a Duffing oscillator that can detect special signals under a high-noise environment. The proposed method monitors electrical characteristics for islanding detection, including frequency, phase angle, and voltage amplitude. The method can quickly and accurately identify when an islanded operation occurs by analyzing these signals. This method combines the advantages of passive and active detection methods while avoiding common drawbacks, such as failed and delayed detection and power quality degradation. The proposed method is tested on a setup and meets IEEE standard 1547 criteria for safety and performance. The method is important because it detects islanded operations in a high-noise environment when the other methods cannot detect islanded operations correctly. The method maintains accuracy with decreased power quality degradation in noise. This method is a cost-effective solution for modern power grids increasingly integrating renewable energy resources.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/120981 |
| Date | 21 August 2024 |
| Creators | Amini, Hossein |
| Contributors | Electrical Engineering, Mehrizi-Sani, Ali, Centeno, Virgilio A., Liu, Chen-Ching |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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