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Operation of instantaneous power theory (PQ) is effective in symmetric systems and has proved to yield erroneous results with asymmetric sources. Synchronous detection algorithm (SDA) distributing averaged equal power among each phase has eliminated the drawbacks in the former. Further improvements with modified synchronous detection algorithm (MSDA) simulation were carried for distorted three phase...
This paper presents a modified, stub tapped hybrid ring coupler for broadband harmonic suppression. In the new design, a tapped stub is used to realize 900 transmission line sections of the conventional coupler. The slow wave effect and the stopband produced by shunt open stub are utilized to achieve the size reduction and harmonic suppression respectively. Explicit design equations are derived using...
The definition of reactive power in three phase system under non sinusoidal situation by various methods are discussed. The effect on power factor improvement and harmonic distortion by energy storage compensation by various definitions is compared using matlab simulation. Adequate filter capacitors are designed to attain the desired power factor and to reduce the distortion factor.
Single-phase and three-phase topologies of the bi-directional a.c. controller, comprising power MOSFET embedded four-quadrant switch (4QSW) realizations operating in high-frequency chopping mode are presented. The performance of the controller with resistive load is assessed from the power quality perspective. A three-phase three-wire resistive load is considered for the three-phase topology and the...
It has been established that a voltage source converter when used as a power quality compensator can be used for bidirectional active power exchange across the dc bus, simultaneously. However, it may not be possible to execute all the tasks together to their fullest requirements, if the converter operation is restricted within a specified kVA rating. To ensure the safety of the semiconductor devices...
This paper presents a unique comparison between Wavelet Packet Transform (WPT) and Discrete Wavelet Transform (DWT) in the power system harmonics scenario. The signals used are actual tested waveforms which have been obtained using power quality analyzer. The results obtained using WPT and DWT are then compared with IEEE Standard 1459 - 2000 based values. The percentage error has been calculated for...
This paper presents a novel high performance generalized discontinuous pulse width modulation (GDPWM) algorithm for reduced current ripple without angle and sector estimation. The conventional space vector modulator with equal division of zero state vectors time is modified to generate different discontinuous modulating waves. A constant-variable mu ranging from 0 to 1 is used to generate infinite...
Identification of gene locations in a DNA sequence is one of the important problems in the area of genomics. Nucleotides in exons of a DNA sequence show f = 1/3 periodicity. The period-3 property in exons of eukaryotic gene sequences enables signal processing based time-domain and frequency-domain methods to predict these regions. Identification of the period-3 regions helps in predicting the gene...
This paper shows the application of S-transform in identifying the voltage disturbances such as sag, interruption, swell and harmonics. S-transform is suitable for the analysis of power quality disturbances under noisy condition as it has excellent time-frequency resolution characteristics and has the ability to detect the disturbance correctly. Various voltage disturbances are generated as per IEEE...
A novel scalar control technique based on resistance emulation for harmonic elimination for a single phase shunt active filter (SAF) system is proposed in this paper. The control objective of the filter is to regulate the voltage source inverter using a closed loop PI controller so as to emulate a resistance across input sinusoidal source. In such a case, input voltage and current will have the same...
This paper presents a novel, high frequency soft switching variable speed DC drive with three phase input source. In the proposed scheme, a single switch has been deployed to operate continuously in zero current switching mode with three phase AC input source. The output of the proposed drive is continuously controllable. DC voltage required for driving DC motor in its entire speed and torque range...
According to the essential operational principle of High Power Factor PWM rectifier, a simulation model of AC constant power load is proposed. The input current of this model is ensured to follow the input voltage and the consistence in their waveforms is achieved. This model can calculate the RMS of input current and then generate an appropriate current waveform corresponding to the harmonics contained...
For low conversion ratios boost rectifier has a power factor less than unity when operated in discontinuous conduction mode and constant duty cycle. This paper proposes a simple duty cycle modulation technique to reduce the line harmonics and improve the power factor of the boost rectifier, even for low conversion ratios. A periodic voltage signal is used to vary the duty cycle of the boost switch...
This paper investigates the effects of harmonics on core and windings of a sinusoidal supplied transformer for two different loading conditions: linear and nonlinear. When harmonics exist, transformer variables, such as core resistance current, magnetic inductance current and excitation current, become non-sinusoidal. This means that the core resistance and magnetic inductance shows nonlinearity under...
In this paper, a new topology of DSTATCOM (Distribution Static Compensator) is proposed consisting of a two-leg VSC (voltage source converter) and a zig-zag transformer for power quality improvement in three-phase four-wire distribution systems. The DSTATCOM along with a zig-zag transformer is employed for the compensation of reactive power for the voltage regulation or power factor correction along...
Presence of torque pulsation in an inverter fed motor drive is evident when inverter operates in square wave mode. This paper presents qualitative and quantitative approach to access the torque pulsation in an open-loop inverter fed five-phase induction motor drive system. A method is proposed to reduce the torque pulsation in transient and steady-state conditions otherwise present in the motor due...
The widespread application of power electronics is introducing non-linear loads in the distribution system resulting in the distortion of current and voltage waveforms. In this paper, IEEE 13-bus distribution system is considered for analysis of harmonics. The distribution system model is simulated in PSCAD/EMTDC software with static and adjustable speed drives as loads. Harmonic analysis of the system...
In power systems the primary requirement is to find a rigorous approach to suppress the harmonics and ultimately extract the fundamental frequency component. The method presented enables the FIR filter design satisfying specific frequency characteristics with auxiliary constraints. The job of design is converted to an optimization problem with the constraint using standard mean square criterion. The...
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