A novel 9-level multilevel inverter based on 3-level NPC/H-bridge topology for photovoltaic applications
- Authors: Wanjekeche, T. , Jimoh, A. A. , Nicolae, Dan-Valentin
- Date: 2009
- Subjects: Harmonics , Photovoltaic power generation , Electric power generation
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/21278 , uj:16136 , Citation: Wanjekeche, T, Jimoh, A.A. & Nicolae, D.V. 2009. A novel 9-level multilevel inverter based on 3-level NPC/H-bridge topology for photovoltaic applications. International Review of Electrical Engineering, 4(5):769-777. , ISSN: 1827-6660
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Analysis of synchronous reluctance machine with magnetically coupled three-phase windings and reactive power compensation
- Authors: Ogunjuyigbe, A. S. O. , Jimoh, A. A. , Nicolae, Dan-Valentin , Obe, E. S.
- Date: 2010
- Subjects: Synchronous machinery
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/18578 , uj:16017 , ISSN :17518660 , Citation: Ogunjuyigbe, A.S.O. et al. 2010. Analysis of syhnchronous reluctance machine with magnetically coupled three phase windings and reactive power compensation. IET Electric Power Applications, 4(4):291-303. , DOI:10.1049/iet-epa.2009.0134
- Description: Abstract: Synchronous reluctance machine with simple salient rotor is known to have poor power factor because of its poor reactance ratio. This study presents the use of an auxiliary winding attached to a balanced capacitor to improve the effective reactance ratio as well as the performance characteristics of synchronous reluctance machine. A unique feature of this configuration is that although the machine runs at synchronous speed, the effective reactance ratio of the machine can be improved by appropriate sizing of the capacitor attached to the auxiliary winding, with the constraint of the ampere turn rating of the auxiliary winding. The operational characteristics of a simple salient rotor synchronous reluctance machine equipped with this configuration were investigated and shown to have a desirable performance. How the effective reactance ratio, power factor and airgap flux distribution depend on the size of capacitor attached to the auxiliary winding is determined using a simplified mathematical model of the system. Analytical results and experimental measurements are in good agreement, and demonstrate the effectiveness and benefits of the configuration
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Automating consumer's connections to the distribution network for enhanced performance
- Authors: Popoola, O. M. , Jimoh, A. A. , Nicolae, Dan-Valentin
- Date: 2010
- Subjects: Power electronics , Electric circuit breakers , Voltage detectors
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/18674 , uj:16029 , ISSN:1827-6660 , Citation: Popoola, O.M., Jimoh, A. & Nicolae, D.V. 2010. Automating consumer's connections to the distribution network for enhanced performance. International Review of Electrical Engineering, 5(5), October 2010.
- Description: Abstract:Trial and error approach which involves service interruption is usually carried out to resolve unbalance on phases in power distribution system. This approach might improve the phase voltage and current but the resultant effect (change) does not last for too long; thereby reduces the market value in terms of quality and reliability of supply. To enhance the performance of the secondary distribution system there is a need for an automating technology. The aim of this paper is to introduce a method and technology developed for resolving imbalances in a secondary distribution system as a result of the uneven distribution of single phase load across a three phase power system. The technology developed is able to monitor, acquire/display collected data and perform self changing switching actions electronically. This action is in form of rearrangement or transfer of consumer loads for optimal performance of the distribution feeder. The proposed switching technology is based on open- transition switch that enables transfer or rearrangement of consumer loads in a three-phase system within milliseconds with supervisory control system. The following methodologies: System Simulator - Matlab (Simulink), Virtual Instrumentation-Lab VIEW and Hardware implementation were applied for the validation of the proposed technique
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Complete analysis of a multilevel inverter based on 3 level NPC/H- bridge topology for photovoltaic application
- Authors: Wanjekeche, T. , Nicolae, Dan-Valentin , Jimoh, A. A.
- Subjects: Bridge circuits , Capacitance meters , Electric power measurement
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/18262 , uj:15978 , Citation: Wanjekeche, T., Nicolae, D.V. & Jimoh, A.A. 2010 Complete analysis of a multilevel inverter based on 3 level NPC/H- bridge topology for photovoltaic application. IEEE
- Description: Abstract: The cascaded NPC/H- bridge inverter is first analyzed by establishing a new switching model based on a derived control law, then using the model a general model using state space technique is obtained. A new and accurate average model is developed using abc to dqo transformation technique. A small signal model is developed by linearizing all the state variables around their quiescent operating points. The small signal model is used to study the effects of various control feedback variables on the dynamic performance of the PV- Grid system. Based on the transfer function developed feedback control loop is developed to improve the dynamic response of the system as well as voltage balancing of the DC link. Simulation results are provided to validate the analytical models.
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Performance analysis of capacitance compensated dual stator winding synchronous reluctance machine
- Authors: Ogunjuyigbe, A. S. O. , Jimoh, A. A. , Nicolae, Dan-Valentin , Obe, E. S.
- Date: 2010
- Subjects: Capacitance meters , Synchronous machinery , Torque
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/18633 , uj:16024 , ISSN:1827-6660 , Citation: Ogunjuyigbe, A.S.O. et al. 2010. Performance analysis of capacitance compensated dual stator winding synchronous reluctance machine. International Review of Electrical Engineering,5(2), April 2010:437-446
- Description: Abstract: Synchronous reluctance machine with simple salient rotor are known to have poor power factor because they have a low effective reactance ratio. This paper used a 3 phase auxiliary winding and balanced capacitance compensation to ifluence the effective reactance ratio of a synchronous reluctance machine with simple salient rotor structure, such that its power factor and torque/ampere performance is improved. A mathematical model and dq equivalent circuit suitable for dynamic and steady state analysis was developed and used to study the synchronous operation of this machine.Analytical as well as experimental results for a 4-pole, 36 slots simple salient rotor reluctance machine showed that the effective reactance ration increased with the capacitance size, and the machine operated at a maximum power factor of 0.969 without altering the geometry of the rotor. the torque per ampere of the machine also improved with the size of capacitor attached to the auxilary winding.
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