Subsynchronous oscillations (SSO) were an issue that occurred in the past with conventional generators and were studied extensively throughout the years. However, with the rise of inverter-based resources, a new form of SSO emerged under the name subsynchronous control interaction (SSCI). More specifically, a resonance case occurs between Type-3 wind turbines and series compensation that can damage equipment within the wind farm and disrupt power generation. This work explores the types of SSCI and the various analysis methods as well as mitigation of SSCI. The work expands on the concept of frequency scan to be able to use it in an on-line setting with its output data used to mitigate SSCI through the modification of wind turbine parameters. Multiple frequency scans are conducted using PSCAD/EMTDC software to build a lookup table and harmonic injection is used in a parallel configuration to obtain the impedance of the system. Once the impedance of the system is obtained then the value of the parameters is adjusted using the look-up table. Harmonic injection is optimized through phase shifts to ensure minimal disruption of the steady-state operating point and is conducted using Python programming language with PSCAD Automation Library. Simulation results demonstrate the effectiveness of this approach by ensuring oscillations do not grow exponentially in comparison to the regular operation of the wind farm. / Master of Science / Due to climate change concern and the depletion of fossil fuel resources, electrical power generation is shifting towards renewables such as solar and wind energy. Wind energy can be obtained using wind turbines that transform wind energy into electrical energy, these wind turbines come in four different types. Type-3 wind turbines are the most commonly used in the industry which use a special configuration of the classical induction generator. These wind turbines are typically installed in a distant location which makes it more difficult to transfer energy from its location to populated areas, hence, series capacitors can be used to increase the amount of transferred energy. However, these series capacitors can create a phenomenon called subsynchronous control interaction (SSCI) with Type-3 wind turbines. In this phenomenon, energy is exchanged back and forth between the series capacitors and the wind turbines causing the current to grow exponentially which leads to interruptions in service and damage to major equipments within the wind turbine. This work explores SSCI, the tools to study it, and the currently available mitigation methods. It also presents a method to identify the cases where SSCI can happen and mitigates it using adjustable parameters.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/104657 |
| Date | 16 August 2021 |
| Creators | Alatar, Faris Muhanned Lutfi |
| Contributors | Electrical Engineering, Mehrizi-Sani, Ali, Kekatos, Vasileios, Liu, Chen-Ching |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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