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Power Distribution system is polluted by harmonic and reactive power disturbances due to the large usages of non-linear loads (Computers, Laser printers, SMPS, Rectifier etc.). Harmonics cause a number of undesirable effects like heating, equipment damage and Electromagnetic Interference effects in the power system. Active power filter (APF) or Active power line conditioner (APLC) is a suitable solution...
This paper present three-phase four-wire active filter for power line conditioning (PLC) to improve power quality in the distribution network. The active power filter (APF) is implemented with PWM based current controlled voltage source inverter (VSI). This VSI switching signals are generated through proposed three-level hysteresis current controller (HCC) that achieves significant reduction in the...
This paper presents a mathematical model of a doubly fed induction generator (DFIG) in the positive synchronous reference frame under distorted grid voltage conditions. The oscillations of the DFIG's electromagnetic torque and the instantaneous stator active and reactive powers are fully described when the grid voltage is harmonically distorted. Four alternative control targets are proposed to improve...
Increasing non-linear loads cause various undesirable effects and power quality problems on utility supply, like low system efficiency, poor power factor, derating of power supply equipments, disturbance to other consumers and interference in nearby communications networks etc. This work proposes a parallel power processing scheme to improve the power quality of uncontrolled diode bridge rectifier...
Apart from the traditional pulse-width modulation (PWM) or SPWM voltage source inverters (VSI), the proposed VSI with a Proportional integral current controller (PI VSI) offers superiority. They include instantaneous current control and wave shaping, fixed inverter switching frequency independent of the output frequency resulting in only known harmonics, and free-running carrier operation. A modeling...
Voltage Source Converter (VSC) technology is very common in high-voltage direct current (HVDC) transmission systems. Compared to conventional VSC technology Modular Multilevel Converters (MMCs) offer advantages such as higher voltage levels, modular construction, longer maintenance intervals and improved reliability. For power transmission, stability, robustness of the control and especially the behavior...
Phase locked loop (PLL) is an important part of the current-controlled grid-connected converter. Its job is to estimate the phase angle of the grid voltage. If the PLL is not robust, the grid-voltage distortion will lead to an error in the estimated phase leading to a degradable performance of the converter. In this paper, the effect of the PLL on the operation of a current-controlled voltage-source...
The paper describes the active power filter structure, control algorithms and methods for filter current regulation. Firstly, there is described the structure of parallel active filter power part, their resonant DC - link and structure of active filter general conception. Then there is described the control algorithms and methods for filter current regulation. The paper is mainly orientated to control...
Growing numbers of consumers distort AC networks with harmonics. Therefore suppression of the network pollution should be considered. This problem can be solved by using "network-friendly" converters. In this article some consumers are presented that pollute the single-phase AC networks with harmonics. Therefore the network voltage waveform will be distorted. In our study we examine the...
In this paper, a neural network based reference current computation method for active power filter (APF) control under non-ideal mains voltage with different load condition is proposed. The neural network controller has been designed to extract fundamental frequency components from non-sinusoidal and unbalanced currents. These fundamental frequency components will be used as unit templates. The APF...
In this paper, a novel neural network based phase locked loop (PLL) less reference current computation method for active power filter (APF) control under non-ideal mains voltage conditions with different load condition is proposed. The neural network controller comprises two similar adaptive linear neurons (ADALINE), and it has been designed to extract fundamental frequency components from non-sinusoidal...
Multiphase machines have higher reliability than 3-phase machines. In order to produce smooth torque after one or more phases are open circuit, the stator magnetic motive force (MMF) is kept unchanged. This paper presents fault-tolerant current control strategies of a concentrated winding multiphase machine under open-circuited fault conditions. In a concentrated winding multiphase machine, other...
Static power converters produce harmonics due to the nature of the conversion process. This paper will investigate the effect on the power factor of a sinusoidal and Fryze current reference on a PWM boost type rectifier. It has been shown in previous papers that a Fryze current ref is best. This paper will develop a mathematical model, based on the single sided Fourier expansion. Using this mathematical...
This paper investigates the interactions which arise between grid connected photovoltaic inverter systems and the electrical grid. In particular, it considers the effect of grid voltage harmonics and grid impedance on the current control performance of grid connected inverter systems. In these photovoltaic inverter systems it is usual to control unity power factor, sinusoidal, current into the grid...
This paper deals with shunt active power filtering for power quality improvement under unfavourable non-linear load and source conditions. A simple hybrid control strategy is used, based on a numerical integrator proportional (IP) DC bus controller combined with a phase-locked loop (P.L.L.) output to generate reference currents. A second analogue current controller is developed to insure- three phase...
This paper presents a shunt active power filter application mainly for source current harmonic elimination. The proposed control method is based on instantaneous reactive power theory. A three-phase voltage source inverter bridge with a dc bus capacitor is used as an APF. It requires measuring the source currents with reduced number of current sensors than the existing methods. The source currents...
Static power converters produce harmonics due to the nature of the conversion process. This paper will investigate two variations of current mode control for three-phase power converters ensuring reduced harmonic pollution and power factor improvement. The first method employed uses a Fryze current reference and the second method utilises a balanced three-phase sinusoidal reference. Both control techniques...
A Virtual Air Gap Variable Reactor is a device that is capable of producing a continuously variable reactance with a better dynamic response and without introducing the harmonics created by the thyristor switching of a TCR. This paper presents a method of harmonic mitigation that can be applied to a laboratory prototype Virtual Air Gap Variable Reactor (VAG-VR) which further improves on the low harmonics...
Multiphase motor drives are multi-dimensional systems, so multiphase vector control and SVPWM must be implemented in a multi-dimensional vector space. In this paper, multi-dimensional multiphase vector control is developed based on a novel multiphase SVPWM strategy, which could synthesize the required voltage vectors not only in d-q subspace but also in other subspaces. Therefore, all voltage and...
The significant drawback of the permanent magnet linear synchronous motor (PMLSM) is force ripples, which are generated by the distortion of the stator flux linkage distributions, cogging forces caused by the interaction of the permanent magnet and the iron core and the end effects. This will deteriorate the performance of the drive system in high precision applications. The PMLSM and its parasitic...
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