Comparative Study of PID Based VMC and Fuzzy Logic Controllers for Flyback Converter

In this paper performance of flyback converter by using PID controller and Fuzzy controller are studied, compared and analyzed. The above study is done for 200W, 230V A.C input 48V DC output. Design of fuzzy controller is based on the heuristic knowledge of converter behaviour, and tuning of fuzzy inference requires some expertise to minimize unproductive trial and error. The design of PID control is based on the frequency response of the converter. For the DC-DC converters, the performance of the fuzzy controller was superior in some respects to that of the PID controller. The fuzzy controller is easily to develop, they cover a wide range of operating conditions, and they are more readily customizable in natural language terms. Simulation is done in Matlab environment to show the performance variations of above mentioned converters using both Fuzzy & PID controllers

An Analytical Approach for Loss Minimization and Voltage Profile Improvement in Distribution Systems with Renewable Energy Sources

Loss minimization and voltage profile improvement are of prime importance in distribution system operation. This paper presents an analytical approach for coordinating distributed energy resources to reduce the active power loss in distribution networks. The proposed approach is based on the network admittance matrix and has an explicit solution if all loads in the network are constant current loads. Furthermore, it is shown that when loads are modeled with other characteristics such as constant power loads, a numerically efficient solution of loss minimization can also be obtained. The resulting solution reduces network losses while ensuring a nominal voltage at the point of common coupling. Case studies on a 19-node distribution system are presented to validate the proposed approach

Impact of non-idealities on the Performance of an Ultracapacitor based Bidirectional DC/DC Converter

This paper analyses the impact of non-idealities on the performance of an ultracapacitor based bidirectional DC/DC converter. In particular, this work analyses the impact of ON state resistance of the MOSFET switches on the performance of bidirectional DC/DC converter. It is shown that, under particular operating conditions, the ON state resistance of the MOSFET can have a significant impact on the performance of th DC/DC converter and can cause an unstable response. An analytical expression is derived to identify the operating conditions under which the non-idealities can have a significant impact on the performance of the DC/DC converter. Simulation results are presented to aid the analysis reported in this paper. © 2020 IEEE

Multimode Operation of a PV-Battery System fed Brushless DC Motor Drive

Utilization of energy storage systems along with Photovoltaic systems, can provide an efficient solution to overcome the challenges associated with renewable energy sources. This paper proposes an algorithm for the multimode operation of a Brushless DC motor drive fed using a combination of Photovoltaic System and battery-based energy storage. Based on the solar irradiation and the state of charge of the battery, the proposed algorithm identifies a control scheme wherein the entire system operates in Four different modes. The working of the PV-Battery System fed Brushless DC Motor Drive under various operating modes is presented and is verified using simulation analysis performed in MATLAB/Simulink. © 2020 IEEE

Basic science232. Certolizumab pegol prevents pro-inflammatory alterations in endothelial cell function

Background: Cardiovascular disease is a major comorbidity of rheumatoid arthritis (RA) and a leading cause of death. Chronic systemic inflammation involving tumour necrosis factor alpha (TNF) could contribute to endothelial activation and atherogenesis. A number of anti-TNF therapies are in current use for the treatment of RA, including certolizumab pegol (CZP), (Cimzia ®; UCB, Belgium). Anti-TNF therapy has been associated with reduced clinical cardiovascular disease risk and ameliorated vascular function in RA patients. However, the specific effects of TNF inhibitors on endothelial cell function are largely unknown. Our aim was to investigate the mechanisms underpinning CZP effects on TNF-activated human endothelial cells. Methods: Human aortic endothelial cells (HAoECs) were cultured in vitro and exposed to a) TNF alone, b) TNF plus CZP, or c) neither agent. Microarray analysis was used to examine the transcriptional profile of cells treated for 6 hrs and quantitative polymerase chain reaction (qPCR) analysed gene expression at 1, 3, 6 and 24 hrs. NF-κB localization and IκB degradation were investigated using immunocytochemistry, high content analysis and western blotting. Flow cytometry was conducted to detect microparticle release from HAoECs. Results: Transcriptional profiling revealed that while TNF alone had strong effects on endothelial gene expression, TNF and CZP in combination produced a global gene expression pattern similar to untreated control. The two most highly up-regulated genes in response to TNF treatment were adhesion molecules E-selectin and VCAM-1 (q 0.2 compared to control; p > 0.05 compared to TNF alone). The NF-κB pathway was confirmed as a downstream target of TNF-induced HAoEC activation, via nuclear translocation of NF-κB and degradation of IκB, effects which were abolished by treatment with CZP. In addition, flow cytometry detected an increased production of endothelial microparticles in TNF-activated HAoECs, which was prevented by treatment with CZP. Conclusions: We have found at a cellular level that a clinically available TNF inhibitor, CZP reduces the expression of adhesion molecule expression, and prevents TNF-induced activation of the NF-κB pathway. Furthermore, CZP prevents the production of microparticles by activated endothelial cells. This could be central to the prevention of inflammatory environments underlying these conditions and measurement of microparticles has potential as a novel prognostic marker for future cardiovascular events in this patient group. Disclosure statement: Y.A. received a research grant from UCB. I.B. received a research grant from UCB. S.H. received a research grant from UCB. All other authors have declared no conflicts of interes

Analysis of Low Voltage Ride Through Techniques for Grid-Connected Photovoltaic Systems

This paper presents a comparative analysis of different low voltage ride though strategies proposed for operation of a grid connected two stage photovoltaic system under low voltages. The existing grid codes mandate that, under the presence of low voltages, a distributed energy resource (DER) must stay connected to the grid for a minimum amount of time. This results in abnormally high currents though the inverter of a PV system, which can potentially damage the semiconductor switches. To avoid this, low voltage ride through techniques are proposed in the literature to ensure that the DER stays connected to the grid. Traditionally, the performance of LVRT techniques is evaluated by assuming an ideal voltage dip at the point of common coupling. In this work, comparative evaluation of different LVRT techniques is carried out on the CERTS test bed with an objective to highlight the impact of network transients on their performance. © 2020 IEEE

A New Formulation for Load Flow Solution of Power Systems With Series FACTS Devices

this paper addresses the solution of load flow equa-tions for a power system with series flexible ac - transmission systems(FACTS) devices. A novel formulation of equations using dual state variables (current magnitude and angle) and dual controlvariables (series injected real power and series voltage in quadra-ture with current) for series devices is proposed. These specifica-tions can be related to transmission line loading and device limits.Specifications like power flow through a series device can also be handled using this formulation. The load flow equations are solved using Newton-Raphson technique. A decoupled formulation is also proposed. Case studies are carried out on IEEE test systems withseveral types of specifications to validate the method

Comparison of Passive Damping based LCL Filter Design Methods for Grid-connected Voltage Source Converters

Distributed generators are typically interfaced to the grid via power electronic converters that are usually operated in pulse width modulation mode. This results in undesirable higher-order harmonics in currents and voltages that deteriorate the power quality. In order to mitigate these harmonics, a filter is usually connected at the output of the converter before it is interfaced to the grid. The most commonly adopted filter is the LCL filter. This paper analyses the performance of different methods proposed in the literature to design passive LCL filters for a 3- f grid-connected voltage source converter. Various filter design techniques are tested for their compliance with the standards IEEE 519-2014 and IEEE 1547-2018. Further, comparison is carried out in terms of essential system metrics such as reactive power requirement, power factor, and the voltage drop across the filter. The performance of various filter design approaches is analyzed using simulation studies on different distributed generator configurations. © 2020 IEEE