Bio: Chetan Bhardwaj is an academic researcher from DIT University. The author has contributed to research in topics: Medicine & Internal medicine. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.
01 Feb 2016
TL;DR: In this paper, the performance of five control techniques for reference currents extraction of D-STATCOM under balanced, unbalanced and distorted voltage condition is compared in Matlab/Simulink environment.
Abstract: The most important concern regarding a power system is the quality of its power. The main cause of most of the issues is nonlinear loads only. D-STATCOM has turned out to be a good solution to solve this problem because of its ability to compensate reactive power and harmonic components demand of the nonlinear loads. This paper presents comprehensive analysis of comparison the performance of five control techniques for reference currents extraction of D-STATCOM under balanced, un-balanced and distorted voltage condition. The algorithms to be compared are symmetrical components based algorithm, IRP theory, generalized IRP theory, SRF method, and synchronous detection method respectively those are widely used in D-STATCOM. These all algorithms have been simulated in Matlab/Simulink environment. The theoretical study and simulation testing shows the performance and accuracy of considered algorithms in case of balanced unbalanced and distorted source voltage conditions.
TL;DR: In this paper , a 72 year old man presented with progressive dyspnea on exertion, only able to climb 4 stairs prior to symptom onset, and had a history of diffuse large B-cell lymphoma.
Abstract: Case Presentation A 72 year old man presented with progressive dyspnea on exertion, only able to climb 4 stairs prior to symptom onset. He had a history of diffuse large B-cell lymphoma for which he had completed chemotherapy with cyclophosphamide, doxorubicin, rituximab, vincristine, and prednisone a year prior to presentation with recent PET scan showing complete remission. EKG showed rate-controlled atrial fibrillation. TTE confirmed a severely reduced systolic function with LVEF 25% and global hypokinesis. Coronary angiogram revealed no obstructive disease. Cardiac MRI (CMR) was then performed with no evidence of myocardial infarction, infiltration, or scarring on delayed gadolinium enhancement (DGE). T2 mapping, DIR, and TIR sequencing did not show any myocardial edema. However, baseline pre-contrast T1 relaxation time was increased at 1140-1153ms [Figure 1A] with a calculated ECV [Figure 1B] elevated at 37-40%, concerning for anthracycline-induced cardiomyopathy (AIC). Discussion Anthracyclines, such as doxorubicin, are important chemotherapeutic agents; however, their utility is often limited by development of progressive cardiotoxicity. Cumulative dose-dependent exposure can lead to apoptotic myocyte loss, myocardial fibrosis, and dysmotility. DGE usually identifies focal myocardial fibrosis; however, anthracycline-induced fibrosis is frequently diffuse and can be missed by qualitative analysis and DGE burden assessment. Diffuse fibrosis is better demonstrated with use of hematocrit adjusted ECV and pre-/post-T1 mapping. CMR provides additional information about decrease in the LV mass, aortic stiffness, myocardial strain, early fibrosis detection, and myocardial edema that can aid in early detection of cardiotoxicity during anthracycline therapy. Use of CMR parametric imaging is complementary and essential in accurately diagnosing AIC in patients with prior exposure and merits widespread consideration in cardio-oncology.
TL;DR: In this article , a 24-year-old male presented to the emergency department due to progressive shortness of breath and pedal edema over one month, and was admitted to the ICU, he had an appropriate gradual increase in sodium level over the next 4 days.
Abstract: Introduction: Kratom use has been known to the natives of Malaysia to increase energy and to treat pain. Over the recent past there has been an increase in Kratom usage in the U.S. with the ease of access. Case Summary: A 24-year-old male presented to the emergency department due to progressive shortness of breath and pedal edema over one month. The patient reported a history of daily Kratom use for the past 2 years. His vitals upon presentation were BP: 90/50 mmHg, HR 101 bpm, O2 saturation 100% and was afebrile. Relevant abnormal labs were: sodium 114 mEq, and a BNP of 2,747 pg/mL. Other labs including TSH and urine drug screen were unremarkable. Initial ECG showed normal sinus rhythm, right axis deviation and QTc of 552 ms. Chest X ray revealed a prominent pulmonary conus. After being admitted to the ICU, he had an appropriate gradual increase in sodium level over the next 4 days. The transthoracic echocardiogram showed an LVEF of 70-75% and multiple findings suggestive of severe pulmonary hypertension and severe tricuspid regurgitation (Fig. 1 parts A and B). His estimated PASP was 95 mm Hg. Right heart catheterization demonstrated the following pressures (in mmHg): RA 5/6, PA 52/26 (37), mean PCWP 7. Cardiac output and index were 8.9 L/min and 5 L/min/m2 by Fick, 7.7 L/min and 4.3 L/min/m2 by thermodilution. Four weeks after cessation of Kratom use he underwent a transthoracic echocardiogram which showed complete normalization of abnormal findings shown in Fig. 1 parts C and D. His RVSP normalized to 26 mm Hg. Conclusion: Previously reported adverse cardiovascular events from Kratom use include tachycardia, hypertension, chest pain, conduction defects, QTc prolongation as well as cardiac arrest. We present previously unknown complications of Kratom use, namely combined pre and post capillary pulmonary hypertension and high output heart failure.
TL;DR: In this article , a 61-year-old male with biopsy proven polymyositis with history of cardiac arrest secondary to ventricular fibrillation and dual chamber automatic implantable cardioverter defibrillator (AICD) implanted for secondary prevention.
Abstract: Introduction: Polymyositis is an autoimmune systemic disease which is characterized by chronic weakness and inflammation in skeletal muscle predominantly. Cardiac involvement has been reported and is a poor prognostic factor. Clinical course 61-year-old male with biopsy proven polymyositis with history of cardiac arrest secondary to ventricular fibrillation and dual chamber automatic implantable cardioverter defibrillator (AICD) implanted for secondary prevention. He had recurrent PVC-induced ventricular fibrillation causing AICD shocks. Eventually, he underwent electrophysiology study and successful ablation of PVC targeted to the basal lateral left ventricle.Transthoracic echocardiogram showed unremarkable systolic and akinetic basal inferolateral wall segment.He underwent PET-CT of myocardium which showed focal FDG uptake of the lateral basal left ventricular could indicate focal myocarditis.Endomyocardial biopsy did not show any evidence of myocarditis.Eventually he had recurrent rapid monomorphic ventricular tachycardia and was briefly placed on amiodarone. He was placed on immunosuppressive therapy managed by Rheumatology with etanercept, rituximab and IVIG. No recurrence of ventricular arrythmia has occurred since. Amiodarone has been discontinued. Discussion: Myocardial involvement of polymyositis is not uncommon and has been noted to increase morbidity and mortality.The most common reported manifestations include congestive heart failure, conduction abnormalities which can range from ventricular arrhythmia to complete heart block and coronary artery disease. ConclusionIt is very important to recognize polymyositis as a cause for ventricular arrhythmias in the right clinical setting as management with immunosuppressive therapy can decrease the burden in ventricular arrhythmias.
TL;DR: This work presents the designing and simulation of a photovoltaic fed Distribution-STATCOM for compensation of harmonics and reactive power of a three phase induction motor based drive and verifies the capability of proposed DSTATCOM model.
Abstract: As a result of rapid advancement in electrical and electronics technologies, the application of power electronics is growing day by day due to the significant advantages offered. But as a downside ...
TL;DR: In this article, a 3-phase shunt active power filter (SAPF) is designed for compensation of harmonics resulted in the feeder current owing to the customer side nonlinearity.
Abstract: Shunt active power filter (SAPF) belongs to the class of custom power devices (CPDs) and offers compensation to harmonics originated owing to customer side nonlinear loads, reactive power and unbalance in the distribution power networks functioning in current control mode (CCM). The performance of a SAPF as a harmonic compensator entirely relies on the control technique i.e. the precise detection of the harmonic current components of load that are necessary to be compensated. In the present work, a 3-phase SAPF, inspired by a Lyapunov function based control approach, has been designed for compensation of harmonics resulted in the feeder current owing to the customer side nonlinearity. A control law is determined in the proposed strategy which makes the derivative of the Lyapunov function consistently a negative one for an entire set of stable states. The DC-link capacitor voltage is regulated at constant reference through the proportional-integral (PI) controller. In this method rating of the shunt active power filter is considerably reduced than the other two broadly employed conventional methods. Furthermore, the harmonic compensation efficacy of the proposed Lyapunov function based SAPF is compared with the one based on other two conventional approaches under four different system scenarios namely a simple nonlinear load with and without utility side voltage distortion, a modified IEEE 13 bus test distribution system loaded with a 3-phase chopper fed direct current (DC) motor drive at a single bus and last especially for increasing the harmonic-constrained penetration level of renewable energy. Results obtained through simulation performed in MATLAB/Simulink shows that total harmonic distortion (THD) of source current and dynamic, as well as steady-state performance with Lyapunov function based controller, is significantly improved than the other two conventional methods. Also, the robust compensation performance of the SAPF empowers it to deal with the high penetration of renewable energy.
TL;DR: A double fundamental signal extracter using third-order signal integrator-based control technique is used for the improvement of power quality of single phase grid interfaced with hybrid wind energy generation system (WEGS) and solar photovoltaic array under weak grid conditions.
Abstract: In this study, a double fundamental signal extracter using third-order signal integrator-based control technique is used for the improvement of power quality of single phase grid interfaced with hybrid wind energy generation system (WEGS) and solar photovoltaic (PV) array under weak grid conditions. The control algorithm is proposed for the extraction of dual fundamental components of load current and to extract fundamental grid voltage for synchronisation to the grid. The main objective of the system is to establish secure, reliable and safe integration while mitigating several power quality issues such as total harmonic distortion (THD) of the grid current, DC current injection. The system operates in distribution static compensator mode in the absence of renewable energy sources and also, maintains the grid current THD as per the limit of the IEEE-519 standard. For optimal power extraction from WEGS as well as the solar PV array, perturb and observe algorithm is used. The prototype developed in the laboratory is tested under different operating conditions such as variable wind speed, grid voltage sag/swell, variable solar insolation, and varying load conditions.
13 Sep 2021
TL;DR: In this article, a Lyapunov function established control method has been modeled for a three-phase SAPF for compensating the harmonic currents generated by industrial motor drives in power distribution networks.
Abstract: SAPF, or Shunt Active Power Filter, is a bespoke power device that adjusts harmonics, improve power factor, and imbalance generated by various forms of non-linear loads in the distribution system. The control mechanism, i.e. the accurate detection of the current constituents, governs SAPF's efficacy as a harmonics compensator. In present work, a Lyapunov function established control method has been modeled for a three-phase SAPF for compensating the harmonic currents generated by industrial motor drives in power distribution networks. In this method, a control law has been found that renders the Lyapunov function continually remains -ive in wholly state values. Further, for keeping a constant reference dc-link capacitor voltage, PI-controller has been used. In MATLAB/Simulink, the technique was evaluated on a reformed test IEEE 13-bus distribution network feeding a three-phase chopper supplied DC motor drive on a solo bus. Comparison of outcomes attained through Matlab simulation also validates that the total harmonic distortion (THD) of source current and dynamic along with steady-state performance is enhanced in comparison to the former traditional approaches. Additionally, the rating of SAPF in the suggested technique has also been found to be considerably reduced in comparison to the other conventional methods.
TL;DR: In this article , a Distribution Static Compensator (D-STATCOM), one of the custom power products is used for compensation of reactive power i.e. unbalance in line thus protecting the electrical system from a polluting (flicker producing) Load.
Abstract: : New technologies, using power Electronics-based concepts, have been Developed to provide protection for Commercial and industrial customers from Power quality problems on the electrical Distribution system known as Custom Power Products. Custom power devices are classified into three categories by their structures such as dynamic voltage regulator (DVR), distribution static compensator (STATCOM) and unified power quality compensator (UPQC). The Distribution Static Compensator (D-STATCOM), one of the custom power product, is a shunt-connected Power electronics-based device, is used for compensation of reactive power i.e. unbalance in line thus protecting the electrical system from a polluting (flicker producing) Load. The STATCOM can be used in place of a traditional static VAR Compensator and offers many advantages. This consists of three phase voltage source inverter, injection transformer, DC LINK. The performance of the STATCOM depends on the control algorithm i.e. the extraction of the current components. So, for this, there are various control algorithms for the control of STATCOM block depending on various theories and strategies like phase shift control