- Title
- Current harmonic compensation of nonlinear loads in a three phase, four wire system
- Creator
- Mtakati, Sibulele Morgen
- Subject
- Harmonics (Electric waves)
- Subject
- Electric power system stability
- Subject
- Electric power -- Conservation
- Date Issued
- 2023-12
- Date
- 2023-12
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10948/66574
- Identifier
- vital:75608
- Description
- Nonlinear loads, in low voltage distribution networks, inject current harmonics which affect the quality of supply voltages. In this work, the power usage of a university student residential complex was logged over a four day period for analysis of harmonic currents injected by nonlinear loads. Student residents use nonlinear loads such as lighting, televisions, computer power supplies, and other household appliances. The harmonic analysis was performed on the quality of voltages in the university’s distribution network, the level of current distortion in the load current and the contribution of triplen harmonics to the neutral current. Standards such as the NRS048-2 (2007), IEEE-519 (2014) and IEC61000-3-2 (2009) are helpful in regulating harmonic levels in the distribution network, however, they cannot guarantee good quality supply. This work further investigates two methods of current harmonic cancellation, i.e. a shunt passive and an active current harmonic cancellation technique. A passive power filter was designed, built, and evaluated for a given nonlinear load to provide selective filtering of the dominant current harmonics. A four branch, shunt, passive filter was considered in this work for implementation in a three phase four wire distribution network due to its attractive possibility to be tuned to two different harmonic components with a minimum number of passive elements. While passive filters may be inexpensive, they suffer from several disadvantages, such as providing fixed compensation, performance that is source impedance dependent, has an inherent risk of system resonance and detuning due to ageing and component variation. To overcome the disadvantages of passive filters, a shunt connected active power filter was designed, built and evaluated to provide adjustable, wide bandwidth and dynamic correction to nonlinear loads for the compensation of harmonic currents, reactive power, and neutral currents. The controller used was an indirect FFT-based technique with a second order generalized integrator (SOGI) filter for voltage synchronization. It was digitally implemented in an FPGA programmed in VHDL to allow for fast parallel processing of input variables.
- Description
- Thesis (M.Eng) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 2023
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (XXX pages)
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Engineering, the Built Environment, and Technology
- Language
- English
- Rights
- Nelson Mandela University
- Rights
- All Rights Reserved
- Rights
- Open Access
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Mtakati, SM.pdf | 12 MB | Adobe Acrobat PDF | View Details Download |