Classification and characterization of three phase voltage dips by space vector methodology

Abstract

A new method is presented to identify and to characterize voltage dips measurements from power quality survey. This method is based on the space vector transformation, which describes the three power system voltages by one complex variable-the space vector. Its representation in the complex plane is used to classify voltage dips. Indeed, for a not disturbed system voltages, the space vector represents a circle in the complex plane with a radius equal to the nominal voltage. It follows the same shape for balanced dips, but with a smaller radius. For unbalanced dips, this shape becomes an ellipse with parameters depending on the phase(s) in drop, dip severity and phase angle shift. Further, space vector characteristics and zero sequence voltage are used for a more precise determination of the voltage dip type. The developed algorithm for voltage dips classification is validated by EMTP simulations and measurement data.

Reactive Power Control for Distributed Generation Power Plants to Comply With Voltage Limits During Grid Faults

“…In [31], only symmetric sags were considered. However, voltage sags are very complex phenomena [4], [12], [32]. As shown in that works, some of the recorded sags are asymmetric and timevarying.…”

“…The effects of such disturbances are important in terms of economic losses, malfunction of devices connected to the grid and in extreme cases, black-outs [4]. To alleviate the adverse effects of grid faults, grid codes from the network system operators dictate the behaviour of DG plants.…”

Frequency and fundamental signal measurement algorithms for distributed control and protection applications

“…Given a three-phase voltage signal with low unbalance, this measurement has an almost entirely FIR type response, due to the steady rotation of the AB vector. The measurement can fail during 2-phase faults due to collapse of the AB vector trajectory [8], and cannot provide amplitude/phase measurements of the 3 phases. Measurement validity can be ascertained by placing suitable limits on the sample-to-sample angular rotation velocity of the AB vector.…”

“…Such a frequency measurement method is proposed in [7], because it can seamlessly ride through any single-phase fault, during which time the AB This paper is a postprint of a paper submitted to and accepted for publication in IET Generation, Transmission and Distribution (GTD) and is subject to IET copyright. The copy of record is available at [http://digital-library.theiet.org/]" and the paper is available through IEEE Xplore at [http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4907255] Page 4 of 26 vector trajectory changes from a circle to an ellipse [8]. However, AB vector angle change in [7] is only measured on a sample-by-sample basis and not averaged over a half-cycle or full-cycle period, and thus must be smoothed substantially to remove the ripple effects introduced by harmonics and unbalance.…”

Space Vector Method for Voltage Dips and Swells Analysis

“…The different types of unbalanced dips can be distinguished by using the ellipse parameters and the zero-sequence voltage. In the particular case of dips with rise of the voltage in the not faulted phase(s), the space vector follows a circle in the complex plane with radius equal to the nominal voltage, as in the [14] that their space vector is composed of positive and negative angular frequency phasors and describes an ellipse in the complex plane (Fig. 3).…”