A decisive evaluation of parks transformation based commonly used voltage detection method

The abc-to-dq0 based voltage detection technique is commonly employed in static transfer switch (STS) applications, which are targeted to protect sensitive loads against variety of disturbances. The technique is quite fast and precise especially in case of balanced disturbances. However balanced events seldom occur as compared to unbalances in supply system. Also there is every possibility that sensitive load may comprise of combination of single phase and three phase loads and therefore to offer a ride through capability during most of events, it is equally important to maintain good power quality at both single-phase and three-phase levels. The effectiveness and the capacity of the detection scheme are analyzed against common disturbances, routine operations of power system, under balanced variations which are within acceptable limits and against unbalances of hybrid nature (simultaneous presence of the sag and swell events). The impact of control elements on the detection process is also discussed.http://www.skit.ac.in/academics/skit-research-journal.htmlam2017Electrical, Electronic and Computer Engineerin

Static transfer switch: Performance evaluation of detection scheme

This paper presents time domain simulation of medium voltage STS (Static Transfer Switch) system. The objectives are (1) to analyze the performance of detection scheme with respect to various types of power quality disturbances and the severity of disturbance (2) to investigate the dependency of detection time on point of initiation of disturbance in voltage wave and (3) to investigate the impact of switching transients on the performance of detection schem

Improving power quality of wind energy conversion system with unconventional power electronic interface

The increasing interest to utilize wind energy as a power source prompted more researches to be dedicated to the unconventional integration of this power source into the current grid. In this paper, one avenue to achieve this efficient utilization, through the use of integrated wind energy conversion system (WECS) using doubly fed induction generator (DFIG) is presented. Wind grid integration brings the problems of voltage fluctuation and harmonic distortion. This paper presents an Unconventional Power Electronic Interface (UPEI) to reduce the total harmonic distortion (THD) and enhance power quality during disturbances. The models used in the paper includes a pitch-angled controlled wind turbine model, a DFIG model, power system model and an UPEI having controlled converters. A phase to phase fault is simulated on 132 kV bus and the measured results obtained from grid connection of the wind generation system are presented. The results have demonstrated the ability of UPEI to regulate pitch angle, VAR and to reduce THD. The proposed system increases the effectiveness of the utilization of wind energy

Performance analysis of high speed power quality disturbance recognition scheme for static transfer switch application

The static Transfer Switch (STS) is a network reconfiguring device and is used for power quality improvement of sensitive loads. It selects, at high speeds, between two or more sources of power and provides the best available power to the sensitive load. This paper presents fundamentals of solid state STS with a detailed emphasis on power quality disturbance recognition scheme, as it is responsible for fast and accurate detection of disturbances, thereby ensuring healthy transfer of load to an alternate source. Extensive simulations are carried out for investigating the performance of rather commonly employed detection scheme. The behavior of detection scheme is analyzed against various types of disturbance scenarios including system transients

Past and Present Scenario of Imaging Infection and Inflammation: A Nuclear Medicine Perspective

Nuclear medicine techniques provide potential non-invasive tools for imaging infections and inflammations in the body in a precise way. These techniques are further exploited by the use of radiopharmaceuticals in conjunction with imaging tests such as scintigraphy and positron emission tomography. Improved agents for targeting infection exploit the specific accumulation of radiolabeled compounds to understand the pathophysiologic changes involved in the inflammatory process and correlate them with other chronic illnesses. In the recent past, a wide variety of radiopharmaceuticals have been developed, broadly classified as specific radiopharmaceuticals and nonspecific radiopharmaceuticals. New developments in positron emission (leveraging 18 F and 18 fluorodeoxyglucose) and heterocyclic/peptide chemistry and radiochemistry are resulting in unique agents with high specific activity. Various approaches to visualizing infection and inflammation are presented in this review, in an integral manner, that give a clear view of the existing radiopharmaceuticals in clinical practice and those under development

Affine arithmetic-based dynamic operating reserve quantification considering correlated load and renewable uncertainties

Operating reserves (OR), alongside other ancillary services, are essential for mitigating the increasing uncertainty in generation from Intermittent Renewable Energy Sources (IRES). Traditional OR are determined based on rules of thumb, such as reliability considerations (N - 1 or N - k ), and they neglect the uncertainty between dispatch intervals. Load–generation imbalances lead to excessive reliance on regulation reserves and out-of-merit dispatch. Highlighting this, recent literature has focused on developing models for dynamic reserve quantification. While the models significantly enhance the traditional static reserve quantification, they heavily rely on probabilistic approaches. Despite their effectiveness, probabilistic approaches are computationally complex and necessitate precise historical data. Furthermore, most studies do not consider the correlation between load and IRES when determining reserves, leading to inaccurate estimation and impacting the system’s economics. Affine arithmetic-based models emerge as a promising solution, offering the ability to estimate correlated uncertainties with reduced computational complexity. This paper contributes to developing affine arithmetic models for OR quantification, considering IRES and load correlated uncertainties. Two distinct approaches to reserve quantification are explored: (1) deterministic scheduling with exogenous OR quantification, and (2) affine arithmetic-based scheduling framework to quantify and allocate OR endogenously. A comparative analysis is conducted with probabilistic scenario-based method and interval arithmetic scheduling. The effectiveness of the models is analyzed on the Great Britain test system with 40% renewable integration. Numerical results highlight that around 99% of the probabilistic net-load scenarios are within the net-load bounds generated by the proposed methodology. The reserve requirement is minimized by approximately 8% during peak hours and 35% during off-peak hours with correlated uncertainty. Furthermore, AA-based approach achieved a 15% reduction in total operating cost during the considered operational time-frame, compared to interval arithmetic optimization

Simulation of wind power impact on the transient fault behaviour of grid-connected wind turbine

This paper deals with the analysis of the possible adoption of a static synchronous compensator (STATCOM) with grid-connected constant-speed wind turbines. Three different cases are simulated using Matlab/Simulink for investigating wind-power impact on a power grid connected to wind turbines. The simulations yield information on (i) how the faults impact on the wind turbines and (ii) how the STATCOM influences the post-fault behaviour of the power system. In this paper, an attempt is made to compare the impact, in terms of voltages and active and reactive powers, of adding wind turbines and STATCOM to an electrical power grid. The simulations show that the goal of keeping turbines operational can be achieved

Past and Present Scenario of Imaging Infection and Inflammation: A Nuclear Medicine Perspective

Nuclear medicine techniques provide potential non-invasive tools for imaging infections and inflammations in the body in a precise way. These techniques are further exploited by the use of radiopharmaceuticals in conjunction with imaging tests such as scintigraphy and positron emission tomography. Improved agents for targeting infection exploit the specific accumulation of radiolabeled compounds to understand the pathophysiologic changes involved in the inflammatory process and correlate them with other chronic illnesses. In the recent past, a wide variety of radiopharmaceuticals have been developed, broadly classified as specific radiopharmaceuticals and nonspecific radiopharmaceuticals. New developments in positron emission (leveraging 18 F and 18 fluorodeoxyglucose) and heterocyclic/peptide chemistry and radiochemistry are resulting in unique agents with high specific activity. Various approaches to visualizing infection and inflammation are presented in this review, in an integral manner, that give a clear view of the existing radiopharmaceuticals in clinical practice and those under development