Tomáš Radil

PQ Monitoring System for Real-Time Detection and Classification of Disturbances in a Single-Phase Power System

This paper presents a system for detection and classification of power quality (PQ) voltage disturbances. The proposed system applies the following methods to detect and classify PQ disturbances: digital filtering and mathematical morphology are used to detect and classify transients and waveform distortions, whereas for short- and long-duration disturbances (such as sags, swells, and interruptions), the analysis of the root-mean-square (RMS) value of the voltage is employed. The proposed combined approach identifies the type of disturbance and its parameters such as time localization, duration, and magnitude. The proposed system is suitable for real-time monitoring of the power system and implementation on a digital signal processor (DSP).

New Spectrum Leakage Correction Algorithm for Frequency Estimation of Power System Signals

A new algorithm for the estimation of the frequency of single-tone signals is presented in this paper. The algorithm works in the frequency domain and is based on best fitting a theoretical spectrum of a single-tone signal that is windowed using a rectangular window on the spectrum of the sampled signal. Using this iterative process, the algorithm compensates the spectrum leakage caused by incoherent sampling and a finite number of samples. Due to leakage compensation, the algorithm provides accurate estimates of the signals frequency, amplitude, and phase. The influence of noise and harmonic and interharmonic distortions on the proposed algorithm was investigated and is reported here. The algorithms performance was compared with several other frequency-estimation algorithms (mostly those working in the frequency domain). Since the algorithm is intended for power quality measurements (although it is not limited to this application), it was also tested on signals measured in a single-phase power system.

Impedance Measurement With Sine-Fitting Algorithms Implemented in a DSP Portable Device

The development and implementation of a digital-signal-processor (DSP)-based portable impedance-measurement instrument is described. The circuit sinewave stimulus is generated by the device using a direct digital synthesizer at the desired measurement frequency. The sine is applied to a reference impedance in series with the unknown impedance. Two analog-to-digital converters (ADCs) acquire multiple samples of the two sine voltages, which are transmitted to the DSP. Sine-fitting algorithms determine the sine amplitudes, phases, dc components, and frequency. With these values and the reference-impedance values, the unknown impedance amplitude and phase are determined. Amplifiers, which are included in the device, extend the ADCs input range, while a digital potentiometer enables the adjustment of the reference impedance to improve accuracy.

Automated Power Quality Monitoring System for On-line Detection and Classification of Disturbances

This paper presents a system for detection and classification of power quality (PQ) voltage disturbances. The proposed system applies the following methods to detect and classify the PQ disturbances: digital filtering and mathematical morphology are used to detect and classify transients and waveform distortions, while in case of short and long duration disturbances (such as sags, swells and interruptions) the analysis of the RMS value of the voltage is employed. The decision and classification process is based on disturbances knowledge base of an expert system. The proposed approach identifies the type of the disturbance and its parameters such as time localization, duration and magnitude. The proposed system is suitable for on-line monitoring of the power system and for implementation in a digital signal processor (DSP).

Comparison of nonparametric frequency estimators

This paper deals with the performance of several up-to-date nonparametric frequency estimators. The algorithms of frequency estimation are introduced and their bias, standard deviation and consumption time are compared with regard to the most common signal parameters.

On-line Detection and Classification of Power Quality Disturbances in a Single-phase Power System

A new method for detection and classification of power quality (PQ) disturbances in single-phase power systems is presented in this paper. The method detects transients, waveform distortions and short and long duration disturbances such as sags or swells. The method was developed with special consideration for its suitability for implementation in a digital signal processor (DSP) and for real-time operation. The proposed method was implemented and its performance was verified on detection of real PQ disturbances in a PC based system monitoring a single-phase power system.

DSP based measuring line-scan CCD camera

A simple, flexible and programmable line-scan CCD camera is presented. This camera is designed for measurement purposes such as dimension and position measurements. Camera enables implementation of various signal-processing algorithms as well as usage of various types of CCD sensors

Development of an indoor Wireless Personal Area Network based on mechanically steered millimeter-wave lens antenna

In this paper, the development and early implementation stages of a 60 GHz indoor Wireless Personal Area Network (WPAN) demonstrator is presented. The transmission system is based on a millimeter-wave lens antenna which is mechanically steered to keep track of the transmitting unit. The need for increasing data rate of personal communication systems has led to the use of millimeter-wave systems for indoor use. These systems use the unlicensed spectrum from 57 GHz to 66 GHz. Applications can include for example, the transmission of full HD video or camcorder wireless connection to the home video system. The developed system contains a FPGA based device that receives data from a PC by a USB link, encodes it and sends it to the moveable transmit unit. In the stationary unit end, the received RF power is used in a tracking controller which mechanically steers the receiving antenna beam to maximize the received power. The received signal is also processed by a second FPGA based device which then sends the data by USB to the receiving PC.

An efficient approach to detect and classify power quality disturbances

Purpose – The purpose of this paper is to develop a new method for detection and classification of power quality disturbances such as transients, waveform distortions, sags, swells and interruptions.Design/methodology/approach – For the purposes of the proposed method, the power quality disturbances are divided into two groups. Different algorithms are applied to detect and classify the disturbances from each of the two groups. For the processing of transients and waveform distortions, digital high‐pass filter and the mathematical morphology closing are used. Calculation of the RMS value is used for detection of sags, swells and interruptions.Findings – The proposed method was implemented in a PC‐based measuring setup. The measuring setup was used in a seven‐months‐long monitoring of a single‐phase power system. In the course of the monitoring, the proposed method was verified on over 19,000 transients, 3,500 waveform distortions, 77 sags and 18 interruptions.Research limitations/implications – The classi...

Power quality detection and classification method for IEC 61000-4-30 Class A instruments

This paper describes an improved version of the previously developed method for detection and classification of some power quality disturbances. The new version uses the spectral sincfit algorithm for extraction of the disturbances from the voltage signal. The sincfit algorithm was adapted and optimized for PQ measurements. The proposed method was tested for compliance with the IEC 61000-4-30 Class A requirements.