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He has supported grid-code compliance, EMT studies and de-risking of industrial HVDC schemes for integration of renewable sources, including operational multi-GW scale Offshore Wind Farms. This is our first I IET Renewable Power Generation i Proceedings Special Issue on Upscaling Industrial Electricity Innovations to Deliver Net zero targets. He led both the Offshore Wind Integration and HVDC Innovation Programmes at The UK National HVDC Centre (part of SSEN Transmission), and chaired the technology workstream of the GB Offshore Wind Industry Council (OWIC) Future Transmission group. [Extracted from the article]

This paper proposes an adaptive model of modular multilevel converter (MMC) for electromagnetic transient (EMT) simulations. The model is applicable to MMCs with arbitrary numbers of half-bridge and full-bridge submodules. The proposed design includes average value model, arm equivalent model, and detailed equivalent model. It allows smoothly transitioning from one model to another during time-domain simulations depending on the desired accuracy and execution time constraints. Modifications required in conventional MMC models to achieve smooth transitions are presented in the paper. Time-domain initialization methods are developed for each constituting model, including initialization of the appropriate control system blocks. Validity and effectiveness of the proposed adaptive model is demonstrated using EMT simulations of 401-level MMC-HVDC system. [ABSTRACT FROM AUTHOR]

This paper demonstrates the presence of spurious power losses or generation in the Arm Equivalent Model (AEM) of Modular Multilevel Converters. Such power losses can occur if model equations are not solved simultaneously with surrounding power circuit equations, which is the case when the AEM is implemented using control system blocks in electromagnetic transient simulation software. Depending on operating conditions and simulation parameters, these additional losses can represent a significant part of the total converter station losses or even surpass them, thus making simulation results inaccurate. Analytical demonstration of the losses is presented, and several models that eliminate the losses are proposed. Based on simulation studies, only the variable resistance model and equivalent voltage source model can give accurate simulation results without significantly increasing simulation time and generating or consuming spurious power. [ABSTRACT FROM AUTHOR]

Background: Cesarean section rate has increased dramatically worldwide but there is still debate about the optimum operative technique of cesarean section. Objective: The purpose of this study was to assess the effect of rectus muscle reapproximation at cesarean delivery on the postoperative pain. Methods: This study was a prospective, double-blind, randomized controlled trial. It included 280 primigravidas, with a singleton pregnancy, who underwent elective lower segment cesarean section at term. The patients were randomly allocated into two equal groups; Group (A): undergoing rectus muscle reapproximation, and Group (B): not undergoing rectus muscle reapproximation. Postoperative pain was assessed by visual analogue scale (VAS) from 0 (no pain) to 100 (maximum pain). Postoperative analgesia, operative time, changes in hemoglobin level, length of hospital stay, and occurrence of postoperative complication were also assessed. Results: Postoperative pain score at the end of the first 24 hours and at the end of the next 24 hours were significantly higher among the group of rectus muscle reapproximation (a difference in VAS pain score of: 5, 95% confidence interval: 0.1-11, p value: .02) and (a difference of 1, 95% confidence interval: 0.1-2.9, p value: .01), respectively. As regards the narcotic use in the first 24 hours after cesarean section, in the form of injections of meperidine 50 mg, it was significantly higher among the group of rectus muscle closure (a difference of 10 mg, 95% confidence interval 3-21.7 mg, p value: .02). While in the next 24 hours, the NSAIDs use, in the form of diclofenac sodium injection, was significantly higher among the group of rectus muscle reapproximation (a difference of 10 mg, 95% confidence interval 3.7-31.7 mg, p value: .02). Conclusions: Rectus muscle reapproximation among women undergoing primary caesarian section is associated with significant increase in the postoperative pain and analgesic requirements. [ABSTRACT FROM AUTHOR]