Optimal utilization of frequency ancillary services in modern power systems

The widespread global adoption of wind energy sources has established a significant presence in the existing power grid. However, the massive integration of intermittent wind energy poses forecasting errors, prompting the need for supplementary reserves from conventional energy sources with increased operational expenses and carbon emissions. Hence, to facilitate the seamless operation of large-scale wind-integrated power grids, it is imperative to harness the potential of renewable energy sources and leverage flexible loads to deliver power-balancing services. In this research, dynamic real-time power dispatch strategies have been developed for the Automatic Generation Control (AGC) system to integrate the reserve capacities of conventional generation units and wind power plants and utilize the demand response capabilities of flexible loads for power balancing services. A comprehensive power system grid model was developed in DigSilent PowerFactory software, consisting of coal-based energy systems, wind energy systems, gas turbines, and cold storage units as flexible loads. The study is divided into different case studies to assess the impact of each scenario on system operation in mitigating the forecasting errors of wind power plants. Further, a comparative analysis was performed to illustrate the effectiveness of each case study. The analysis showed that Case Study III, where reserves are provided by coal energy systems and cold storage units, yielded the highest reduction in Positive Regulation (PR) and Negative Regulation (NR) errors, at 89.0% and 94.15%, respectively. Conversely, Case Study IV demonstrated the least reduction in errors, with 67.82% in PR and 78.41% in NR. However, it indicates that reserves can be supplied from wind energy systems and flexible loads without the support of conventional power plants

Enhancing Grid Operation with Electric Vehicle Integration in Automatic Generation Control

Wind energy has been recognized as a clean energy source with significant potential for reducing carbon emissions. However, its inherent variability poses substantial challenges for power system operators due to its unpredictable nature. As a result, there is an increased dependence on conventional generation sources to uphold the power system balance, resulting in elevated operational costs and an upsurge in carbon emissions. Hence, an urgent need exists for alternative solutions that can reduce the burden on traditional generating units and optimize the utilization of reserves from non-fossil fuel technologies. Meanwhile, vehicle-to-grid (V2G) technology integration has emerged as a remedial approach to rectify power capacity shortages during grid operations, enhancing stability and reliability. This research focuses on harnessing electric vehicle (EV) storage capacity to compensate for power deficiencies caused by forecasting errors in large-scale wind energy-based power systems. A real-time dynamic power dispatch strategy is developed for the automatic generation control (AGC) system to integrate EVs and utilize their reserves optimally to reduce reliance on conventional power plants and increase system security. The results obtained from this study emphasize the significant prospects associated with the fusion of EVs and traditional power plants, offering a highly effective solution for mitigating real-time power imbalances in large-scale wind energy-based power systems

Doppler sonographic evaluation of intrauterine growth restriction of fetus and its correlation with perinatal outcomes among the population of riverine (char) areas of Barpeta Assam

Background: Intrauterine growth restriction (IUGR) also known as fetal growth restriction (FGR), has been associated with a variety of detrimental perinatal outcomes. FGR is defined as estimated fetal weights (EFW) or abdominal circumference (AC) that fall within the third, or tenth percentiles with abnormal doppler parameters. FGR affects 10-15% of all pregnancies around the world. Methods: Prospective observational study of singleton pregnant women complicated by FGR were enrolled during the study period from September 2021 to August 2022. 100 patients were included in the study. Results: Abnormal umbilical artery flow was seen in 30% of cases, out of which 83% (25) had abnormal perinatal outcome. Out of 100 cases, live births were reported in 94%, stillbirths in 4%, and IUDs in 2%. There were 16 neonatal deaths and 15 neonatal complications among the adverse perinatal outcomes. Intraventricular hemorrhage and neonatal sepsis were the two leading causes of death. Neonatal sepsis, necrotizing enterocolitis and hypoxic ischemic injury was the leading cause of morbidity. Reverse end diastolic umbilical artery Doppler and bilateral uterine artery notch had 100% mortality. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of umbilical artery in predicting perinatal outcome in IUGR were 80.65%, 92.75%, 83.33% 91.43% and 89.47% respectively. Conclusions: Umbilical artery PI is the most sensitive parameter and had highest positive and negative predictive value and Accuracy in relation to adverse perinatal outcomes