Arghya Sarkar

A novel instantaneous power factor measurement method based on wavelet transform

Power factor monitoring is an important challenge in deregulated environment to maintain quality in delivered power as well as tariff assessment. In this paper, a unique power factor measurement method has been proposed that can measure the instantaneous power factor of a non-sinusoidal single-phase system accurately at every sample instant. The wavelet transform (WT) has been utilized for multiresolution analysis (MRA) of current waveform. The scheme has been implemented in real time with a Texas Instruments (TI) TMS320VC5416 digital signal processor (DSP) along with data acquisition system card PCI-02. The result has been found to be satisfactory

Bandpass Second-Degree Digital-Integrator-Based Power System Frequency Estimation Under Nonsinusoidal Conditions

A novel digital signal processing algorithm for online estimation of the fundamental frequency of the distorted power system signals is presented. The basic algorithm relies on the development of an efficient variance reduction algorithm; and design of a new stable bandpass infinite impulse response (IIR) second-degree digital integrator (SDDI) with reduced approximation error. Compared with the well-established technique such as the enhanced-phase-locked-loop (EPLL) system, the proposed algorithm provides the following: 1) higher degree of immunity and insensitivity to harmonics and noise and 2) faster response during step frequency change. Structural simplicity, wide range of application, controls over speed and accuracy, and parameter robustness are other salient features of the method. The only limitation as compared with the EPLL system is its slower transient response during step change in signal magnitude. Based on simulation studies, performances of the proposed algorithm at different operating conditions have been presented, and its accuracy and response time have been compared with the EPLL systems.

A Low-Cost Fault-Tolerant Real, Reactive, and Apparent Power Measurement Technique Using Microprocessor

Errors may creep in when measuring power by conventional methods due to the inductance and capacitance of the coils and the induced eddy current in the metal parts of the instruments through the alternating magnetic field of the current coil. Apart from these, if a fault occurs in any of the potential transformer secondary circuits or the potential coil of the measuring equipment, a conventional meter cannot detect it, which results in underregistration. In this paper, a microprocessor-based threephase real, reactive, and apparent power measurement system is developed, which displays the power being fed to a load under both normal and faulty conditions. The microprocessor provides a simple, accurate, reliable, and economical solution to these problems. A framework of the hardware circuitry and the assembly language program for the evaluation of power values is given, and the problems to which attention should be paid to execute the proposed algorithm using the microprocessor are discussed. Illustrative laboratory test results confirm the validity and accurate performance of the proposed method in real-time.

The Nonuniform Discrete Short Time Fourier Transform - A New Tool for Electrical Power Components' Monitoring

This paper presents a new discrete short time Fourier transform (DSTFT) implementation algorithm, called nonuniform discrete short time Fourier transform (NDSTFT) for real time estimation of power components according to the IEEE Standard 1459-2000. The proposed NDSTFT algorithm is capable of detecting the spectrum of each finite short time section of the power signals at arbitrarily located specified frequencies and is able to perform sample by sample processing, thus, suitable for real time implementation in uniprocessor system. The NDSTFT based power components estimation algorithm has been implemented in real time by means of a Texas Instruments TMS320VC5416 digital signal processor. Fast and accurate estimation of power components has been observed utilizing the developed scheme.

A simple algorithm for power system frequency estimation

This paper presents development and implementation of a novel digital signal processing algorithm for on-line estimation of the fundamental frequency of nonsinusoidal power system signal. The algorithm relies on stable band-pass second degree digital integrator (BPSDDI) based rigorous mathematical deduction and recombines itself with zero-crossing avoiding technique. The proposed algorithm provides high degree of immunity and insensitivity to harmonics and noise, and fast response during time varying conditions. Structural simplicity, wide range of application, controls over speed and accuracy, and parameter robustness are other salient features of the method. The simulation results confirm the validity and accurate performance of the proposed approach under different operating conditions.

Design and Implementation of a High Accuracy Sampling Wattmeter under Non-sinusoidal and Time Varying Environments

Errors may creep in when measuring active power under non-sinusoidal and time varying conditions by conventional regularly spaced sampling digital wattmeter (RSSDW) due to the existence of higher order voltage and current harmonics, and asynchrony between the signal fundamental frequency and the sampling rate. This paper presents design and implementation of a modified regularly spaced sampling digital wattmeter, called M-RSSDW, immune to above mentioned drawbacks of RSSDW. The proposed method utilizes a novel first degree digital integrator design technique to diminish the effects of higher order harmonics. The truncation error during asynchrony has also been reduced using numerical compensation method. M-RSSDW has been implemented in real time by means of a TMS320VC5416 digital signal processor. The laboratory test results confirm the accuracy of M-RSSDW under both static and dynamic conditions.

DSP implementation of a novel envelope analysis approach for the diagnosis of broken rotor bar in induction motor

Design and implementation of a novel technique for the detection of broken rotor bar of the induction motor is presented. At first, the discrete wavelet transform (DWT) is performed on the windowed steady state stator currents and then discrete Hilbert transform is utilised to obtain envelopes of the detailed coefficients at higher wavelet level. It has been observed that the faulty motor produces higher statistical parameters – mean, rms, standard deviation and median of the envelopes than those for the healthy one. The method is implemented in real time by means of low cost TMS320VC5416 fixed point digital signal processor (DSP). A framework of assembly language program for the calculation of the DWT is given and the problems which should be paid attention during real time implementation are discussed. Illustrative laboratory test results confirm the validity and accurate performance of the proposed method.

A Novel Digital Signal Processing Algorithm for On-line Assessment of Power System Frequency

An innovative, computationally efficient digital signal processing algorithm has been proposed to evaluate the fundamental frequency of a non-sinusoidal power system signal at every sample instant. This approach adopts backward difference approximation as second derivative FIR filter to estimate the instantaneous frequency. Besides this, an efficient square root algorithm, based on iterative Newton-Raphson inverse (NRI) method is also presented to get high accuracy in fixed point processor. The method is illustrated and evaluated in real time by means of a Texas Instruments (TI) TMS320VC5416 digital signal processor (DSP). The experimental results confirm the validity and accurate performance of the proposed approach even under slow magnitude and frequency variations.