Voltage disturbance evaluation using the missing voltage technique

-In the present paper, a novel fast peak detector for single-or three-phase unsymmetrical voltage sags is proposed. The proposed detector is modified from a single-phase digital phase-locked loop based on a d-q transformation using an all-pass filter (APF). APF generates a virtual phase with 90° phase delay. However, this virtual phase cannot reflect a sudden change of the grid voltage in the moment of voltage sag, which causes a peak value to be significantly distorted and to settle down slowly. Specifically, the settling time of the peak value is too long when voltage sag occurs around a zero crossing, such as phase 0° and 180°. This paper describes the operating principle of the APF problem and proposes a modified all-pass filter (MAPF) to mitigate the inherent APF problem. In addition, a new fast peak detector using MAPF is proposed. The proposed detector is able to calculate a peak value within 0.5 ms, even when voltage sag occurs around zero crossing. The proposed fast peak detector is compared with the conventional detector using APF. Results show that the proposed detector has faster detection time in the whole phase range. Furthermore, the proposed fast peak detector can be effectively applied to unsymmetrical three-phase voltage sags. Simulation and experimental results verify the advantages of the proposed detector and MAPF.

Section: Conventional Peak Detector With All-pass Filtermentioning

confidence: 99%

“…Most of conventional peak detector methods have time delays, including the RMS method (2-9 ms) [12], the hybrid KF-RMS method (0.5-4 ms) [2], and DVR (2 ms) [11]. Other methods report a delay of 1-4 ms [1], with the maximum delay being generated around 0° or 180° for all methods.…”

Section: Proposed Fast Peak Detectormentioning

confidence: 99%

Novel Fast Peak Detector for Single- or Three-phase Unsymmetrical Voltage Sags

Lee¹,

Cha²

2011

“…The RMS method has a time delay of 2-9 ms [5], the hybrid KF-RMS method has a time delay of 0.5-4 ms [6], and DVR has a 2 ms time delay [7]. Other methods report time delays ranging from 1-4 ms, with the maximum delay being generated at 0° or 180° for all methods.…”

Section: Introductionmentioning

confidence: 99%

Fast Detection Algorithm for Voltage Sags and Swells Based on Delta Square Operation for a Single-Phase Inverter System

Lee¹,

Sung²,

Lee³

2016

-In this paper, a new sag and peak voltage detector is proposed for a single-phase inverter using delta square operation. The conventional sag detector is from a single-phase digital phaselocked loop (DPLL) that is based on d-q transformations using an all-pass filter (APF). The d-q transformation is typically used in the three-phase coordinate system. The APF generates a virtual qaxis voltage component with a 90° phase delay, but this virtual phase cannot reflect a sudden change in the grid voltage at the instant the voltage sag occurs. As a result, the peak value is drastically distorted, and it settles down slowly. A modified APF generates the virtual q-axis voltage component from the difference between the current and the previous values of the d-axis voltage component in the stationary reference frame. However, the modified APF cannot detect the voltage sag and peak value when the sag occurs around the zero crossing points such as 0° and 180°, because the difference voltage is not sufficient to detect the voltage sag. The proposed algorithm detects the sag voltage through all regions including the zero crossing voltage. Moreover, the exact voltage drop can be acquired by calculating the q-axis component that is proportional to the d-axis component. To verify the feasibility of the proposed system, the conventional and proposed methods are compared using simulations and experimental results.

“…There are numerous publications that have proposed voltage sag detection methods and they can be grouped as 1) synchronously rotating reference frame(SRRF)-based, or d-q transformation-based voltage sag detections [10][11][12], 2) instantaneous voltage technique-based or missing voltage-based voltage sag detections [13,14], 3) peak voltage evaluation-based voltage sag detections [15,16], 4) rms evaluation-based voltage sag detections [17,18], 5) time-frequency transformation-based voltage sag detections [19,20], 6) rectified voltage-based voltage sag detections [21] and 7) fractal-based voltage sag detections [22,23].…”

Section: Introductionmentioning

confidence: 99%

An Improvement in Synchronously Rotating Reference Frame-Based Voltage Sag Detection under Distorted Grid Voltages

Sillapawicharn¹,

Kumsuwan²

2013

-This study proposed an improvement in synchronously rotating reference frame-based voltage sag detection under distorted grid voltages. In the past, the conventional synchronously rotating reference frame (CSRRF)-based voltage sag detection was generally used in the voltage sag compensation applications. Its disadvantage is a long delay of detection time. The modified synchronously rotating reference frame (MSRRF)-based voltage sag detection is able to detect the voltage sag with only a short delay in detection time. However, its operation under distorted grid voltage conditions is unavailable. This paper proposed the improvement of modified synchronously rotating reference frame (IMSRRF)-based voltage sag detection for use in distorted grid voltages with very fast operation of voltage sag detection. The operation of the proposed voltage sag detections is investigated via simulations and experimentations to verify the performance of the IMSRRF-based voltage sag detection.