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Islanding detection in distributed generation (DG) interfaced to the microgrid is a key criterion for safety and power quality of the power system. This study proposes a transient monitoring function (TMF)-based islanding detection technique, which distinguishes between various islanding and non-islanding conditions in an inverter-based DG. Initially, the voltage samples of each phase retrieved at the target DG location are processed through Fourier-Taylor transformation (FTT). The TMF is the difference between the estimated voltage samples regenerated from the FTT and the actual sample values. Finally, the TMF index for islanding detection is computed by combining each phase TMF. Based on simulations carried out in PSCAD/EMTDC environment, the performance of the proposed method is examined in various critical conditions. Therefore, the proposed method provides generalised solution irrespective of active and reactive power mismatch and thus enhancing the non-detection zone. The proposed TMF-based anti-islanding relay is highly efficient and satisfies the speed criteria of the relaying function in performing the task. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, the performance of a rectangular patch antenna on inexpensive perforated flexible plastic substrate is investigated experimentally. The antenna is designed for wearable application operating at Wi-Fi and HiperLAN frequency bands. The regular perforations in the substrate material help in reducing the dielectric losses which is common with other textile materials thus improving the antenna performance. The prototype model of the proposed antenna is developed and measured. Various parameters such as return loss, VSWR, radiation pattern and gain are presented to validate the suitability for wearable applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:265-270, 2017 [ABSTRACT FROM AUTHOR]

This study proposes an effective symmetrical fault detection technique during power swing in distance relaying using phase‐space (PS) method. This is based on an embedding theorem which shows that a time series can be mapped to a higher‐dimensional space called PS through embedding. Thus, a sampled signal can be transformed into the PS so that its features can be more clearly viewed. The process starts at retrieving the current signal samples and process through PS, the original signal is decoupled into two parts such as power swing and symmetrical fault part. The symmetrical fault detection during power swing is easily achieved as the symmetrical fault part of the signal produces an irregular shape compared with the shape produced during from the power swing condition. The symmetrical fault detection signal using PS (FDPS) detects the symmetrical fault during power swing in the transmission line with wide variations in operating conditions and the results from extensive studies indicate that the proposed FDPS can reliably detect the faults during power swing. [ABSTRACT FROM AUTHOR]

To improve the performance of the conventional distance protection scheme for compensated lines with high resistance faults, an adaptive distance protection scheme is proposed. This study presents an analytical approach for finding the possible impacts of shunt connected flexible AC transmission systems (FACTS) devices such as static synchronous compensator/static volt‐ampere reactive (VAR) compensator (SVC) integrated with off‐shore wind farm (WF) on distance relay characteristics. Analytical results are presented and verified on simulation platform compares under reach phenomena in presence of both FACTS devices and it is found that under reach is more severe for SVC connected system. Moreover, presence of SVC changes the line characteristic presented to relay even for bolted faults. It is also seen that type of coupling transformer has a considerable effect on apparent impedance. Furthermore, the reach setting of the relay is significantly affected as the relay end voltage and power fluctuates continuously (due to non‐linear relationship with speed) when off‐shore WFs are connected to power transmission systems. Thus, adaptive tripping characteristics for high resistance line‐to‐ground fault with shunt‐FACTS devices considering appropriate operating conditions is a demanding concern and the same has been addressed in the proposed research work. [ABSTRACT FROM AUTHOR]

Ball bearings are considered as a critical element in various mechanical systems. Vibration signal analysis is very effective method for finding bearing fault. Accelerometers are used to capture the multi-component vibration signal generated in the machine when it is in use. Various methods based on empirical mode decomposition (EMD) have been used for ball bearing fault diagnosis. EMD method usually suffered from the boundary distortion of intrinsic mode function. Classification of ball bearing fault is one of the challenging tasks in the field of mechanical systems. Various classification schemes such as support vector machine (SVM), K-means clustering, extreme learning machine (ELM) have been used for the classification of ball bearing fault. In this study, footprint analysis of Hilbert transform along with the neural network has been done for ball bearing fault analysis. A comparative analysis of the proposed research study has been done with available methods such as SVM and ELM. A high fault classification accuracy has been achieved using the proposed method for detection of ball bearing fault. [ABSTRACT FROM AUTHOR]

This study presents an analytical approach for finding the possible impacts of flexible AC transmission system (FACTS) devices such as unified power flow controller (UPFC) and off‐shore wind penetration on distance relay characteristics. Generating relay tripping characteristics is one of the challenging issues for transmission line distance relays as the present day transmission systems is subjected to a more stressed environment with respect to power system operation. Moreover, inclusion of FACTS devices such as UPFC in the transmission system seriously impacts the performance of the distance relays as the apparent impedance changes. Furthermore, the reach setting of the relay is significantly affected as the relay end voltage fluctuates continuously when off‐shore wind‐farms are connected to power transmission systems. Thus, generating tripping characteristics for appropriate operating conditions is a demanding concern and the same has been addressed in the proposed research work. Extensive testing is carried out in generating relay tripping characteristics with possible variations under the operating conditions of UPFC and wind‐farm and it is observed that the characteristics are significantly affected for different operating conditions. Furthermore, the performance of the derived relay characteristics is validated on possible transmission line fault events and is found to work effectively. [ABSTRACT FROM AUTHOR]

Fault‐detection and out‐of‐step protection functions are two important requirements in distance relays while dealing with power‐swing conditions. In the proposed research, the first part focuses on developing wavelet entropy‐based out‐of‐step blocking function during stable power swing and tripping function during unstable power swing. The process starts at retrieving the current signal samples during power swing and process it through wavelet transform to derive singular values, used to find out Shannon entropy, called wavelet singular entropy (WSE). Further, the power swing indicators are computed to distinguish stable power swing from unstable ones. The second part computes WSE‐based indicator to distinguish faults from power swing. The WSE blocks the relay during power swing and issue the tripping signal during fault conditions based on a set threshold. The proposed technique is extensively tested for different stable and unstable power swing conditions providing improved response time for fault detection during power swing and distinguishing stable power swings from unstable ones. [ABSTRACT FROM AUTHOR]

Background To assess the efficacy of 'Judders' as a technique reflecting adequacy of removal of ophthalmic viscoelastic device in cataract surgery. Design Prospective, consecutive, single surgeon study. Participants Cohort of 223 patients undergoing phacoemulsification. Methods 'Judders' are periodic, abrupt, horizontal displacements of the intraocular lens causing balanced salt solution to displace retropseudophakic ophthalmic viscoelastic device. The number of 'Judders' was correlated with axial length, anterior chamber depth, and preoperative and postoperative intraocular pressure. Main Outcome Measures Number of 'Judders', axial length, anterior chamber depth, day 1 postoperative intraocular pressure. Results The mean number of 'Judders' was 3.2. There was a positive association between the number of 'Judders' and axial length, but not between number of 'Judders' and anterior chamber depth. Mean preoperative intraocular pressure was 14.5 mmHg; mean day 1 postoperative intraocular pressure was 15.6 mmHg. Intraocular pressure rose in 47% of cases. In six cases (5%), intraocular pressure rose greater than 10 mmHg (range 11-23 mmHg) from the preoperative level. Conclusions Aspirating ophthalmic viscoelastic device with the irrigation/aspiration tip posterior to the intraocular lens may be associated with the risk of a posterior capsule tear. Maintaining the irrigation/aspiration tip anterior to the intraocular lens may offer a significant safety advantage. The number of 'Judders', usually 3-4, appears to be a safe and reliable end-point of complete ophthalmic viscoelastic device removal. There were significantly more 'Judders' in eyes with a longer axial length. The safety and efficacy of 'Judders' are reflected by the stable mean postoperative intraocular pressure. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented related to the deficiency of carnitine palmitoyl transferase II with reference to normal pressure glaucoma.

A letter to the editor is presented related to the role of clear lens extraction in adult angle closure disease.