Pulse Width Modulation (PWM) Method for Power Components Estimation - Active and Reactive Power Measurement

The scope of this paper is to present the Pulse Width Modulation (PWM) based method for Active Power (AP) and Reactive Power (RP) measurements as can be applied in Power Meters. Necessarily, the main aim of the material presented is a twofold, first to present a realization methodology of the proposed algorithm, and second to verify the algorithm’s robustness and validity. The method takes advantage of the fact that frequencies present in a power line are of a specific fundamental frequency range (a range centred on the 50 Hz or 60 Hz) and that in case of the presence of harmonics the frequencies of those dominating in the power line spectrum can be specified on the basis of the fundamental. In contrast to a number of existing methods a time delay or shifting of the input signal is not required by the method presented and the time delay by n/2 of the Current signal with respect to the Voltage signal required by many of the existing measurement techniques, does not apply in the case of the PWM method as well.

A new application of the least error squares (LES) estimation algorithm is given for identifying, in the time domain, the active and reactive power from available samples of voltage and current waveforms. The digital available instruments used to monitor active, reactive and apparent power use such samples. A new definition for the active reactive and apparent power for sinusoidal and nonsinusoidal waveforms is discussed in this paper. It is shown that misleading reactive power compensation could be obtained if the circuit power factor is not well defined. Simulated results are presented for different waveforms, where the authors compare the results obtained with other available techniques.

ABSTRACTThe present study explores the influence exerted by various pulse width modulation (PWM) techniques upon harmonic distortion and switching losses of a voltage source inverter. In the context of this inquiry, a generalized algorithm for variable frequency operations, inspired by continuous and discontinuous PWM is outlined in this article. The algorithm is explicitly formulated as a function of fundamental frequency and the load power factor angle with the objective of minimizing total harmonic distortion (THD) and switching losses within a specified frequency range. The algorithm is segmented into various regions of frequency, guided by the theory that each region corresponds to a distinct PWM technique that yields reduced harmonic distortion. In this article, a minimum switching loss algorithm is introduced and implemented using both BCPWM and ABCPWM techniques. The algorithm is specifically designed to minimize switching losses across the entire range of load power factor angles. The integration of switching loss algorithm with the selection of the optimal PWM technique across different frequency ranges results in reduced switching losses and harmonic distortion. This leads to a comprehensive PWM algorithm that efficiently reduces both THD and switching losses during dynamic frequency and load changes. Experimental and theoretical evidences demonstrate the efficacy of the proposed algorithm in attaining minimum harmonic distortion and reduced switching loss operation during variations in fundamental frequency and load.

The fundamental frequency of the power supply is a key characteristic of power quality in general-purpose power grids. Deviations of the fundamental frequency from the standard values occur due to an imbalance between power generation and consumption, malfunctions of power plants or power lines. Instability of the fundamental frequency of the power supply voltage leads to a decrease in the efficiency of motors, reduced lifetime of electrical equipment, etc. In power quality monitoring systems, the result of the fundamental frequency measurement according to current standards must be presented as a measured value together with an accuracy indicator in the form of uncertainty. This characteristic depends on various influencing factors, including the measurement method. One of the effective methods for measuring the fundamental frequency is based on the analysis of the phase characteristics of the power supply voltage, which is determined using the Hilbert transform. The purpose of the article is to estimate the uncertainty of measuring the fundamental frequency of the power supply voltage using the phase method, which involves determining the phase characteristic of the voltage using the Hilbert transform. For uncertainty estimates, an Ishikawa diagram was created and an uncertainty budget was justified. To reduce uncertainty in estimating the fundamental frequency, sliding averaging of the phase accumulation was proposed. Simulation experiments showed that this phase method makes it possible to determine the fundamental frequency with a combined standard uncertainty of ~7.5 mHz and a corresponding expanded uncertainty of ~ ±15 mHz (k = 2), which is quite acceptable for power quality monitoring

Fundamental voice frequency in female puberty measured with electroglottography during continuous speech as a secondary sex caracteristic. A comparison between voice, pubertal stages, oestrogens and androgens

Accurate measurement of active and reactive power is becoming increasingly important as problems of process-energy balance become more complicated and cost savings receive more critical attention. In large electrical systems, very special attention must be given to these measurements to maintain losses at a minimum. In the modern panoramic control unit with its attendant off-limit alarms, digital display of these power values is highly desirable. However, because of the nonlinearity of one of the three variables (the product of which defines the power value), direct digital measurements present difficulties. Conventional solid-state digital voltmeter equipment allows the construction of voltage and resistance parameters in a straightforward manner. The third parameter, the sine or cosine of the electrical angle, is a nonlinear function and, therefore, requires more elaborate measuring equipment.

The present series of experiments used factorial designs to evaluate which acoustic features are primarily responsible for the voicing distinction in the syllables /zi/ and /si/. Increases in frication duration tend to make the syllable more voiceless only if vocal cord vibration is absent or at a very low level during the frication period. Increasing the period between the onset of frication and the onset of vocal cord vibration changes the syllable from a pre-dominantly voiced to a predominantly voiceless sound. This period, called voice onset time, can account for the change in perception regardless of simultaneous changes in the total frication duration or the relative duration of the frication period that contains vocal cord vibration. Changes in fundamental frequency had a large influence on the voicing judgments. With low fundamental frequencies, the judgments were predominantly voiced, whereas with high fundamental frequencies, voiceless judgments were predominant. The quantitative judgments of individual observers were described by a ratio-rule model that assumes a multiplicative combination of the independent cues, voice onset time and fundamental frequency. The model also provided a good description of previous studies of the acoustic cues used in the perception of voicing of fricatives.

Power Energy efficiency for public application commonly used driver IC that operate by (Pulse Width Modulation) PWM, The effect of this implementation will generate EMI (Electromagnetic Interference) that can make radio signal distortion or other electronic distortion in the around device area. The action to reduce the signal distortions shall use Filter implementation in the electronic device circuit. The filter to reduce signal distortion are power line filter or ferrite beads filter. Power line filter used for reduce and to filtering noise signal from Power line source from PLN power line or from power line distribution Conduction emission., The ferrite beads filter implementation for noise reduction or filtering from Source power supply to load. Implement of both filters at the circuit diagram will impact to reduce noise signal that make distortion to the signal source.

Multilevel converters with floating capacitors (FCs) are widely applied in recent years in a wide range of industrial applications from high-voltage direct current systems to high power drives. However, some FC topologies lack complete FC voltage balancing capability due to the inherent topology limitation or the insufficient switching state for capacitor balancing. This will result in large ripples on capacitors at low frequency (such as fundamental frequency), limiting their performance and application, particularly, when the fundamental frequency is very low in low-speed drive operations. Typical examples of those multilevel converters are modular multilevel converters (MMC), nested neutral-point-clamped (NNPC) converter, etc. In order to improve the FC balancing for this kind of multilevel converters, this paper proposes a carrier-based pulse-width modulation (PWM) method, named stair edge PWM method. This method can obtain sufficient redundant switching states for FC voltage balancing by producing multiple levels in one PWM period. The FC voltage balancing is thus achieved at switching frequency, which can greatly reduce the capacitor voltage ripple and therefore enable the use of much smaller FCs. Meanwhile, the voltage stress on each device and low $dv/dt$ feature are still the same as the normal multilevel operation, reserving two of the most salient features of multilevel converters. The proposed method also features much simpler and easier implementation compared with space-vector-based approaches, particularly when high-level converters are considered. An application example using a four-level NNPC converter is provided in this paper. The effectiveness and performance of the proposed method are verified by both simulation and experiment.

Interference of power line (PLI) (fundamental frequency and its harmonics) is usually present in biopotential measurements. Despite all countermeasures, the PLI still corrupts physiological signals, for example, electromyograms (EMG), electroencephalograms (EEG), and electrocardiograms (ECG). When analyzing the fetal ECG (fECG) recorded on the maternal abdomen, the PLI represents a particular strong noise component, being sometimes 10 times greater than the fECG signal, and thus impairing the extraction of any useful information regarding the fetal health state. Many signal processing methods for cancelling the PLI from biopotentials are available in the literature. In this review study, six different principles are analyzed and discussed, and their performance is evaluated on simulated data (three different scenarios), based on five quantitative performance indices.

A psychoacoustic experiment to determine the just-discriminable changes in the fundamental frequency of synthetic vowels is described. The experimental parameters investigated are several combinations of four vowels (|i, æ, ɑ, u|), three sound pressure levels (60, 70, and 80 db re 0.0002 dyne/cm2) and two fundamental frequencies (80 and 120 cps). The results indicate that the just-discriminable changes in fundamental frequency are of the order of 0.3 to 0.5 cps, and are, in general, slightly less than the frequency changes discriminable a pure tone of the same frequency and sound pressure level. Application of the the results to speech compression is suggested.

A reflectionless metal tube which can act as a pseudoinfinite termination of the vocal tract was used to collect glottal volume-velocity waveforms produced by 10 male and female adult subjects. From each subject glottal volume-velocity samples were collected of normal, loud, and soft voice; falsetto and creaky voice; monosyllables with rising and failing intonation; and three-syllable utterances containing primary lexical stress on one of the three syllables. Analysis of the data indicates a wide variation of the glottal waveform shape, its rms intensity and fundamental frequency, phase spectrum, and intensity spectrum. It is observed that as the fundamental frequency changes over time, the glottal source varies in one of two different ways. In one type of change, the harmonic relations in the glottal spectrum become steeper as fundamental frequency rises. In a different type of glottal-wave change, relations between harmonics tend to remain the same despite a change in the fundamental frequency; the source spectrum in this case is simply shifted along the frequency and amplitude axes as a function of fundamental frequency. To account for these variations in the glottal source, at least three factors must be known: the sex of the speaker, the voice register in which he phonates, and the linguistic context in which the phonation occurs.

Both one-stage and two-stage schemes of feedforward synchronized pulsewidth modulation (PWM), applied to three-phase voltage source inverter with discontinuous voltage space vector modulation with the 30/spl deg/-nonswitching intervals, have been described in the paper. Different control modes of inverter-fed drive systems with synchronized PWM, including standard scalar V/F control, and control regimes with nonlinear control dependencies between the fundamental voltage and fundamental frequency, have been analysed. Simulations give the behaviour of the PWM schemes and algorithms proposed. The output voltage waveforms of the inverter have quarter-wave symmetry during the whole control range including the zone of overmodulation, and its spectra do not contain even harmonics and combined harmonics, which is especially important for power adjustable speed drive systems with low switching frequencies.

A review of various methods for reactive power measurement is given. It is shown that they give different results under non-sinusoidal conditions. A new technique for parameter estimation of additive harmonics of the fundamental signal frequency taking into account the possible fluctuations of this frequency is given. It bases on the processing of the sampled current and voltage signals by the maximum likelihood method. The proposed technique allows one to obtain the efficient estimates of unknown parameters in linear approximation. The described procedure allows one to measure the reactive power in industrial alternating current networks using any of accepted methods.

A comparison of speech intonation production and perception abilities of Farsi speaking cochlear implanted and normal hearing children