Dynamic residual phasor method for diagnosis of voltage unbalance in a noisy power system
01 Sep 2007-pp 677-680
TL;DR: In this article, a unique fault diagnostic to detect voltage unbalance in a three phase noisy power system is presented by continuously adding the three phase voltages resulting in a residual voltage.
Abstract: This paper presents a unique fault diagnostic to detect voltage unbalance in a three phase noisy power system. This has been achieved by continuously adding the three phase voltages resulting in a residual voltage. This voltage has been transferred to the frequency domain using DFT algorithm through which the fundamental residual voltage phasor is obtained. Training data have been generated through computer simulation which reveals that (i) presence of harmonics in the voltage waveforms does not affect the fundamental component of the residual phasor in the frequency domain and (ii) unbalance in the voltages affect the fundamental component of the residual phasor in phase and magnitude thus making the residual phasor a dynamic one and hence the name. From the results of computer simulation some rules have been generated such that the amplitude and phase angle of the dynamic residual voltage phasor can be used as a diagnostic to detect the unbalance in a power system in a noisy environment. An algorithm is developed using the rules which has been validated through unknown signals in laboratory.
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TL;DR: In this article, the authors propose definitions for power terms in alternating current systems that are practical and effective when voltage and/or currents are distorted or unbalanced, and also suggest definitions for measurable values that may be used to indicate the level of distortion and unbalance.
Abstract: Existing definitions for power terms in alternating current systems work well for single-phase and three-phase systems where both voltages and currents are sinusoidal with respect to time. This paper clarifies and proposes definitions for power terms that are practical and effective when voltage and/or currents are distorted and/or unbalanced. It also suggests definitions for measurable values that may be used to indicate the level of distortion and unbalance.
342 citations
08 Oct 1995
TL;DR: In this paper, a voltage divider model is proposed to estimate the number of voltage sags at a specific load location, and an equivalent expression for the critical distance as a function of the critical phase-angle jump is derived.
Abstract: Based on a simple voltage divider model, a relation is derived between the load sensitivity to voltage sags (expressed as a critical voltage) and the exposed area (expressed as a critical distance). The critical distance increases about linearly with voltage level. The relation found is remarkably similar to relations found in power quality surveys. An equivalent expression is found for the critical distance as a function of the critical phase-angle jump. Realizing that faults downstream of a transformer do not significantly influence the expected number of sags, it is possible to estimate the number of sags at a specific load location. The method is extended to some nonradial systems: simple subtransmission loops, local generation, feeding from two substations, and operating with a normally open breaker.
168 citations
"Dynamic residual phasor method for ..." refers background in this paper
...Different voltage sag assessment methods, their effects and prediction have been presented in [8], [11], [13], [14]....
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23 Jan 2000
TL;DR: In this paper, an overview of methods used in the mitigation of voltage sags is given, and different solutions for improving the performance of the power system, as well as the immunity of the equipment, are described.
Abstract: This paper gives an overview of methods used in the mitigation of voltage sags. Different solutions for improving the performance of the power system, as well as the immunity of the equipment, are described. Finally, mitigation devices to be installed at the system-load interface for power quality enhancement are presented.
111 citations
TL;DR: In this article, the authors assess the compatibility between a piece of equipment and the electricity supply from utility and manufacturer's data, and use prediction methods to quantify this aspect of the quality of the power supply.
Abstract: Customers all over the world experience problems due to power system voltage sags. Computers, industrial control systems, and adjustable-speed drives are especially notorious for their sensitivity. Tripping of high-power adjustable-speed drives is probably the main voltage sag problem. The number of trips depends strongly on the equipment sensitivity. Prediction methods are needed to quantify this aspect of the quality of the power supply. From utility and manufacturer's data, a customer can assess the compatibility between a piece of equipment and the electricity supply.
82 citations
"Dynamic residual phasor method for ..." refers background in this paper
...Different voltage sag assessment methods, their effects and prediction have been presented in [8], [11], [13], [14]....
[...]
04 Jun 1996
TL;DR: A digital instrument for the power quality analysis in systems where voltage or current waveforms are non-sinusoidal is presented, based on a C40 DSP and on a special high-speed data acquisition system.
Abstract: This paper presents a digital instrument for the power quality analysis in systems where voltage or current waveforms are non-sinusoidal. It is based on a C40 DSP and on a special high-speed data acquisition system. The analysis is performed by a recursive algorithm which allows the mutable system properties to be tracked. The paper also goes on to discuss the performance of an instrument prototype, both in terms of accuracy specifications and speed of measurement.
60 citations
"Dynamic residual phasor method for ..." refers background in this paper
...In the light of power quality analysis under non-sinusoidal condition, different attempts [10] have also been made to detect unbalance in a system....
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