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The protection to the sensitive loads from voltage sags, swells and harmonics can be achieved using the dynamic voltage restorer (DVR) in a cost effective manner. In this paper, a new control algorithm based on unit templates and instantaneous symmetrical component theory along with complex Fourier series is used for the generation of reference voltages for a dynamic voltage restorer (DVR). These...
This paper presents a robust hierarchical control system of distributed generation converters for robust microgrid operation and seamless transfer between grid-connected and isolated modes. The proposed control scheme employs 1) an internal model voltage controller with a variable structure control element to provide means for mitigating fast and dynamic voltage disturbances, such as dynamic voltage...
In this paper, a comparative analysis of the carrier based pulse width with modified zero space vector modulation or third harmonics injection used in the inverter control is presented. The placement of zero space vector components with in the carrier interval determines the harmonic performance of the modulation strategy. The space vector pulse width modulated inverter gives 15 percent more line...
In this paper, various multicarrier pulse width modulation techniques are proposed, which can minimize the total harmonic distortion and enhances the output voltages from five level inverter. Multilevel inverters are important for power electronics applications such as flexible ac transmission systems, renewable energy sources, uninterruptible power supplies and active power filters. Three methodologies...
Angular contact bearings are the most popular type of bearings used in the motorized high speed spindle. An initial preload and operating-induced load control are managed to ensure its rigidity, but the centrifugal force and temperature will rise with the rapid increase of spindle speed. Although the centrifugal force and thermo induced bearings load are applied on the spindle assembly. This paper...
This paper presents a novel synchronous reference frame (SRF) controlled five-level cascaded multilevel inverter based shunt active filter for power line conditioners (PLCs) to improve the power quality in the distribution system. The SRF based compensation is developed by sensing load currents only, which require for harmonics and reactive power compensation due to non-linear loads. The attempt is...
In this paper comparison of control strategies used for multilevel inverter based shunt active power filter is presented. Recently use of high voltage nonlinear load is considerably increased in industry and elimination of harmonics in HV system has become an important aspect. Implementation of multilevel inverter (MLI) for active power filter (APF) in HV system eliminates use of bulky and high cost...
This paper proposes the application of Differential Evolution (DE) algorithm to the selective harmonics elimination pulse-width modulation (SHE-PWM) scheme. The aim is to solve for the set of transcendental equations that determine the switching angles of the SHE-PWM waveform. The objective function of DE is designed to minimize the selected harmonics to near zero. Furthermore the fundamental component...
Multilevel inverters are commonly modulated by using multicarrier pulse width modulation techniques such as phase-shifted multicarrier modulation and level-shifted multicarrier modulation. However, level-shifted multicarrier modulation technique produces the best harmonic performance than the phase-shifted multicarrier modulation technique. But it is having apparent disadvantages of unequal device...
Pulse width-modulated (PWM) inverters are used more and more to operate electrical machines and to interface renewable energy systems with the utility grid. However, there are abundant high-frequency harmonics in the output voltage of a PWM inverter, which increase the iron losses and result in derating of the machine or transformer connected to them. Predicting the iron losses caused by the PWM supply...
This paper proposes a simple harmonic feedback strategy for reduction of output voltage harmonics and the removal of any voltage unbalance due to unbalanced linear and non-linear loads in three-phase inverters. The fundamental components of the voltage and current are controlled in dq frame. Two-phase observers have been used for estimating the fundamental αβ components of the inverter voltage and...
This paper presents the development of a state-of-the-art remotely controlled single phase Sinusoidal Pulse Width Modulated (SPWM) inverter with the incorporation of RISC microcontroller. A provision of remote control from a PC in addition to the local control is incorporated in order to control the functionality of the inverter. The microcontroller itself generates the required pulse according to...
This paper deals with an innovating Shunt active filter with PI controller for harmonic elimination. Active filter provide a viable solution to mitigating harmonic issues caused by the non linear loads. The active filter compensates the reactive and harmonic currents drawn by the non-linear loads besides power factor correction. The objective is to study different control strategies for real time...
In this paper, various novel pulse width modulation techniques are analysed, which can enhances the output voltages from five level inverter to multilevel topologies. Multilevel inverters are important for power electronics applications such as flexible ac transmission systems, renewable energy sources, uninterruptible power supplies and active power filters. Three methodologies adopting the constant...
This paper presents an improved PWM strategy for three-phase inverters, especially suited for use at low ratios of switching frequency to fundamental output frequency. The method of third-harmonic injection is used to ensure maximum utilisation of the DC bus voltage. Implementation issues for the new modulation strategy are discussed. A comparison with a conventional, regularly sampled PWM is presented,...
The paper reports unexpected failures of ultrahigh speed induction machine (USIM) supplied by PWM converter applied in a system developed for utilizing renewable and waste energies. Due to the high supply frequency of USIM the frequency ratio in the PWM converter was unusually low. The imperfect operation of the microcontroller commanding the PWM pattern generated subharmonics. It developed considerable...
The configuration of a single-phase AC-DC converter plus a three-phase inverter traction system has been widely applied in high-speed railway electrical drive systems. With the single-phase power feeder, the instantaneous power is fluctuating at twice of the power line frequency, and so is the DC-link voltage. Associated with the DC-link voltage fluctuation is a severe problem, when the electric frequency...
This paper presents an efficient Differential Evolution (DE) based solution for harmonic elimination pulse-width modulation (HEPWM). The aim is to solve for the set of transcendental equations that determine the switching angles of the HEPWM waveform. The objective function of the DE is designed to minimize (to near zero) the selected harmonics and at the same time allows for the fundamental component...
We introduce a novel analytical approach to the evaluation of harmonic content in multi-level inverters. An analytical formula for the phase voltage total harmonic distortion (THD) of any multi-level pulse-width modulation (PWM) signal is introduced. As opposed to conventional THD expression where full spectral knowledge of the signal is required, the proposed formula depends only on fundamental amplitude,...
Synchronization is essential for the satisfactory operation of VSI in high power applications. With proper selection of switching states it is possible to obtain synchronization and symmetry in space vector pulse width modulation (SVPWM) algorithm. A novel SVPWM based switching algorithm, which results in improved THD and increased fundamental voltage in overmodulation region by maintaining synchronization...
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