The design of space vector control (SVC) systems suitable for flux-weakening operation of permanent magnet brushless DC machines (PMBDCMs) is presented in this study. The proposed design approach enables overcoming th...
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The design of space vector control (SVC) systems suitable for flux-weakening operation of permanent magnet brushless DC machines (PMBDCMs) is presented in this study. The proposed design approach enables overcoming the critical issues arising from the non-linearities of PMBDCM voltage and torque equations;these issues derive from the trapezoidal shapes of back-emfs and affect PMBDCM constraint management significantly. The SVCs presented in this study have been developed within two different synchronous reference frames, both of which enable distinguishing torque and demagnetising current components clearly. Therefore, reference torque current component is determined in accordance with PMBDCM torque demand, while reference demagnetising current component is computed through a voltage follower PI regulator, which processes the voltage deficit detected on the DC-link. In this regard, a novel synchronousreference frame is proposed in this study, which improves PMBDCM constraint management and results into a wider constant-power speed range, but at the cost of some torque ripple. The enhanced performances achievable by SVC approaches are highlighted by numerical simulations, which regard the comparison among the SVCs and an SVC with no flux-weakening capability, at different operating conditions.
Voltage source inverters (VSI) connected to intermittent renewable sources may have periods of low active power production. When the power generated at the source is below the power rating of the inverter, the remaini...
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ISBN:
(纸本)9781467386173
Voltage source inverters (VSI) connected to intermittent renewable sources may have periods of low active power production. When the power generated at the source is below the power rating of the inverter, the remaining unused rating of the inverter can be used to compensate the harmonic distortion in the grid. This paper presents the realization of a VSI with Active Power Filter capabilities, which is able to control the compensation of individual load harmonics up to the 17th as a function of the variation of the unused rating of a VSI. In order to select the number and magnitude of harmonic to mitigate, the paper analyses the utilization rating of the VSI in light of the power theory used in the latest IEEE standards. This analysis results in the derivation of a novel "power sphere" concept that is helpful to establish the magnitude of harmonic compensation needed to fully utilize the unused rating of a VSI at a given time. The performance of the selective compensation of individual harmonics in a VSI is validated in simulations and in a 3-phase 1kW DSC-controlled experimental platform.
Tracking harmonic currents and voltages in electric power systems with custom power devices exceeds the capabilities of conventional Proportional+integral controllers and more sophisticated algorithms are required, es...
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Tracking harmonic currents and voltages in electric power systems with custom power devices exceeds the capabilities of conventional Proportional+integral controllers and more sophisticated algorithms are required, especially under grid-frequency variations. This paper presents a control method based on multiple referenceframes for harmonic control in the context of a series active power filter. The proposed scheme allows recursive calculation when referring signals to referenceframes rotating synchronously with harmonic equivalent space vectors whilst a minimum of trigonometric-function evaluations are required. Furthermore, the control of each harmonic can be dealt with using simple integral controllers applied to the transformed signals. The paper presents the closed-loop-stability analysis and experimental results of a series active power filter. A scenario with grid-frequency variations is considered to show the intrinsic adaptation capability of the proposed controller. (C) 2015 Elsevier Ltd. All rights reserved.
This paper presents the analysis and the control of shunt-compensator for improving unbalanced voltages of power distribution systems in Thailand. The shunt-compensator is connected to the low voltage level in power d...
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ISBN:
(纸本)9780646494883
This paper presents the analysis and the control of shunt-compensator for improving unbalanced voltages of power distribution systems in Thailand. The shunt-compensator is connected to the low voltage level in power distribution system. The analysis detail and the design of shunt-compensator obtain by using the voltage vector control (mathematical model with the stationary reference frame and synchronous reference frames). The unbalanced voltages are identified by using positive and negative sequence detection that can be shown in the synchronousreference frame. This method also presents the decoupling control including feed-forward control to compensate both positive and negative sequence component of grid voltage. The power circuit of the shunt-compensator and the distribution network are modeled by Provincial Electricity Authority (PEA) of Thailand that is the same as worldwide standard of power distribution system. By using computer program, the simulation results showed the benefit and the performance of proposed methodology which obviously ensure the performance of shunt-compensator for mitigating the unbalanced voltages.
This paper presents the analysis and the control of shunt-compensator for improving unbalanced voltages of power distribution systems in Thailand. The shunt-compensator is connected to the low voltage level in power d...
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This paper presents the analysis and the control of shunt-compensator for improving unbalanced voltages of power distribution systems in Thailand. The shunt-compensator is connected to the low voltage level in power distribution system. The analysis detail and the design of shunt-compensator obtain by using the voltage vector control (mathematical model with the stationary reference frame and synchronous reference frames). The unbalanced voltages are identified by using positive and negative sequence detection that can be shown in the synchronousreference frame. This method also presents the decoupling control including feed-forward control to compensate both positive and negative sequence component of grid voltage. The power circuit of the shunt-compensator and the distribution network are modeled by Provincial Electricity Authority (PEA) of Thailand that is the same as worldwide standard of power distribution system. By using computer program, the simulation results showed the benefit and the performance of proposed methodology which obviously ensure the performance of shunt-compensator for mitigating the unbalanced voltages.
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