A seven-level cascaded multilevel inverter based on simplified SVPWM method

The multilevel converters are extremely widespread alternatives within megawatt power level as well as medium voltage level applications due to their excellent execution than the typical two-level converters. The widely applied control strategies aimed at inverters are Sine Pulse Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM) strategies. In between these two PWM methods, the SVPWM strategy has excellent execution as compared to the SPWM strategy as a result of improved DC link voltage use as well as a decrease in Total Harmonic Distortion (THD) in output voltages. A traditional SVPWM strategy owns numerous weaknesses like computational complications in terms of identification of the reference voltage vector position, to identify sector, triangle and also it requires large memory for storing look up tables used for switching vectors. This paper presents, an innovative modified SVPWM strategy aimed at Cascaded H-Bridge Multilevel Inverter (CHBMLI). The novel modified SVPWM strategy has overwhelm the downsides of traditional SVPWM strategy. A seven-level CHBMLI is used for the implementation of this simplified SVPWM method to assess performance and as well to made comparison with the SPWM strategy. A MATLAB software is used for the simulation

5-level torque-hysteresis controller for DTC based IM drive

In the recent trade demand, the AC machines and drives are extensively utilized. Normally, the AC drives exploit with high efficacy as well as high performance. Among other things, one of the best control strategies is Direct torque control (DTC). For this article, the induction motor drive is projected very simple amended DTC scheme in accordance with the hysteresis controller. By the reason of its modest assembly & effective execution, DTC is used for AC as well as DC drive as associated to other monitoring structures. The presence of high ripple content in output torque for DTC scheme is only an obstacle. This article approaches extenuation of the ripples in torque by varying the predictable 5-level torque hysteresis controller used in DTC. The expansion of distinctive switching approach has been generated for chosen voltage vector. On the basis of ripple content simulation outcomes fulfilled in MATLAB/SIMULINK for hysteresis torque controller to minimized the ripples

Taking stock of 10 years of published research on the ASHA programme: Examining India’s national community health worker programme from a health systems perspective

Background: As India’s accredited social health activist (ASHA) community health worker (CHW) programme enters its second decade, we take stock of the research undertaken and whether it examines the health systems interfaces required to sustain the programme at scale. Methods: We systematically searched three databases for articles on ASHAs published between 2005 and 2016. Articles that met the inclusion criteria underwent analysis using an inductive CHW–health systems interface framework. Results: A total of 122 academic articles were identified (56 quantitative, 29 mixed methods, 28 qualitative, and 9 commentary or synthesis); 44 articles reported on special interventions and 78 on the routine ASHA program. Findings on special interventions were overwhelmingly positive, with few negative or mixed results. In contrast, 55% of articles on the routine ASHA programme showed mixed findings and 23% negative, with few indicating overall positive findings, reflecting broader system constraints. Over half the articles had a health system perspective, including almost all those on general ASHA work, but only a third of those with a health condition focus. The most extensively researched health systems topics were ASHA performance, training and capacity-building, with very little research done on programme financing and reporting, ASHA grievance redressal or peer communication. Research tended to be descriptive, with fewer influence, explanatory or exploratory articles, and no predictive or emancipatory studies. Indian institutions and authors led and partnered on most of the research, wrote all the critical commentaries, and published more studies with negative results. Conclusion: Published work on ASHAs highlights a range of small-scale innovations, but also showcases the challenges faced by a programme at massive scale, situated in the broader health system. As the programme continues to evolve, critical comparative research that constructively feeds back into programme reforms is needed, particularly related to governance, intersectoral linkages, ASHA solidarity, and community capacity to provide support and oversight

Adaptive digital distance relay for SSSC‐based double‐circuit transmission line using phasor measurement unit

The existence of midpoint series flexible alternating current transmission system (FACTS) devices leads to degrade the performance of mho relay, leading in erroneous estimation of fault location, ie, overreach or underreach for wide variation in network parameters. This research article proposes a novel mho relay algorithm to improve the performance of distance relay in presence of FACTS device using phasor measurement unit (PMU). First, the complete model of transmission system employing static synchronous series compensator (SSSC) and its control strategy is described analytically, where the error introduced in measurement of impedance due to SSSC on the performance of distance relay. Second, a novel mho relay procedure is developed based on PMU to protect the first zone of double‐circuit transmission line for single line‐to‐ground (SLG) fault. The proposed work is analysed and simulated with 48‐pulse SSSC carried out with Bergeron model of transmission line using power system computer‐aided design (PSCAD) computer simulation. Finally, the simulation results represent that the suggested adaptive scheme is truthful, reliable, and secure with change in compensation level of SSSC.http://wileyonlinelibrary.com/journal/etep2020-04-01hj2019Electrical, Electronic and Computer Engineerin

Effect of SSSC-based SSR controller on the performance of distance relay and adaptive approach using synchronized measurement

The use of series compensation in a transmission line with capacitors may result in new problems like torsional oscillations in shaft sections of turbine‐generator due to subsynchronous resonance (SSR) when system frequency matches with any one of torsional mode frequency of shaft system during fault or disturbances occur in the transmission line. The subsynchronous current due to SSR during fault also affects the reach of a distance protection system. The diminution of SSR is enhanced by series voltage injection into the power transmission line with static synchronous series compensator (SSSC) from the knowledge of subsynchronous components, extracted from the system. The use of SSSC in transmission line reduces the subsynchronous oscillations, but it adversely affects the distance protection system which leads to an imprecise assessment of fault location, ie, over or under‐reach. This paper investigates the SSR mitigation in the presence of SSSC and its effect on distance protection scheme. A new approach is proposed for mitigating the problems associated with distance protection by using the synchrophasor measurement. The entire study of simulation is investigated by using a 48‐pulse SSSC carried out with Bergeron model of transmission line in PSCAD. The simulation results represent that the suggested adaptive scheme is truthful, reliable, and secure with a change in compensation level of SSSC.http://wileyonlinelibrary.com/journal/etep2019-11-01hj2018Electrical, Electronic and Computer Engineerin