IMPROVEMENT OF POWER QUALITY OF HYBRID GRID BY NON-LINEAR CONTROLLED DEVICE CONSIDERING TIME DELAYS AND CYBER-ATTACKS

Power Quality is defined as the ability of electrical grid to supply a clean and stable power supply. Steady-state disturbances such as harmonics, faults, voltage sags and swells, etc., deteriorate the power quality of the grid. To ensure constant voltage and frequency to consumers, power quality should be improved and maintained at a desired level. Although several methods are available to improve the power quality in traditional power grids, significant challenges exist in modern power grids, such as non-linearity, time delay and cyber-attacks issues, which need to be considered and solved. This dissertation proposes novel control methods to address the mentioned challenges and thus to improve the power quality of modern hybrid grids.In hybrid grids, the first issue is faults occurring at different points in the system. To overcome this issue, this dissertation proposes non-linear controlled methods like the Fuzzy Logic controlled Thyristor Switched Capacitor (TSC), Adaptive Neuro Fuzzy Inference System (ANFIS) controlled TSC, and Static Non-Linear controlled TSC. The next issue is the time delay introduced in the network due to its complexities and various computations required. This dissertation proposes two new methods such as the Fuzzy Logic Controller and Modified Predictor to minimize adverse effects of time delays on the power quality enhancement. The last and major issue is the cyber-security aspect of the hybrid grid. This research analyzes the effects of cyber-attacks on various components such as the Energy Storage System (ESS), the automatic voltage regulator (AVR) of the synchronous generator, the grid side converter (GSC) of the wind generator, and the voltage source converter (VSC) of Photovoltaic (PV) system, located in a hybrid power grid. Also, this dissertation proposes two new techniques such as a Non-Linear (NL) controller and a Proportional-Integral (PI) controller for mitigating the adverse effects of cyber-attacks on the mentioned devices, and a new detection and mitigation technique based on the voltage threshold for the Supercapacitor Energy System (SES). Simulation results obtained through the MATLAB/Simulink software show the effectiveness of the proposed new control methods for power quality improvement. Also, the proposed methods perform better than conventional methods

Impact of Using Online Health Management Tools on Patient Perception of Healthcare Quality: A Multiple Chronic Conditions and Generational Perspective

While access and adoption issues related to online health management tools (OHMT) have been studied in healthcare contexts, questions remain about whether and how their use impacts patients’ perceptions of healthcare. Drawing on technology affordance and media synchronicity frameworks, we explore how the existence of multiple chronic conditions (MCC) and differences in usage pattern due to patient’s generation impact these relationships. Utilizing HINTS data, this study provides empirical support for a positive relationship between utilization of electronic personal health records (e-PHRs) and healthcare quality perceptions, albeit with a caveat that patients with greater healthcare needs as well as millennial and younger generations do not seem to enjoy the same benefits from increased use of e-PHRs. Furthermore, asynchronous patient-provider electronic communication is yet to achieve positive perceptions of better healthcare quality for most users. This research bears implications for personalization and customization of OHMT to account for variations in patients’ healthcare needs and usage patterns

Phospholipid Requirement for Mitochondrial Calcium Channel and Its Implications in Barth Syndrome

Biochemical interactions between macromolecules form the basis of life. Among different macromolecular interactions present in living systems, we still lag in our understanding of how lipids influence the structure and function of proteins in biological membranes. To this end, I developed yeast Saccharomyces cerevisiae phospholipid mutants as a surrogate system to dissect the in vivo phospholipid requirements of the mitochondrial calcium import machinery – the uniporter complex. I first focused on mitochondrial calcium uniporter (MCU), the pore-forming subunit of the uniporter complex, for the following reasons. First, it is an integral inner mitochondrial membrane protein that is a key regulator of mitochondrial bioenergetics. Second, MCU is not present in S. cerevisiae, providing a “clean” system to interrogate its phospholipid requirements in a physiologically relevant mitochondrial membrane. Third, mitochondrial calcium signaling has been implicated in a number of human diseases, however, the phospholipid requirements of MCU have remained unknown. I used heterologous expression to functionally reconstitute protozoan and human MCU in wild type yeast as well as in mutants defective in the biosynthesis of the most abundant mitochondrial phospholipids, phosphatidylcholine, phosphatidylethanolamine, or cardiolipin (CL), to uncover a CL-specific requirement for the stability and activity of MCU. My findings from the yeast model system are applicable to higher organisms as shown by the reduced abundance and activity of endogenous MCU in cells and cardiac tissue of Barth syndrome patients that have inherited deficiency in CL levels. In a follow-up study, I showed that the partial loss of CL in Barth syndrome disease models also results in rapid turnover of mitochondrial calcium uptake 1 (MICU1), the principal regulator of the uniporter complex. The CL-deficiency induced decrease in MCU and MICU1 disrupts mitochondrial calcium signaling such that calcium-stimulated mitochondrial bioenergetic pathways are blunted in cellular models of Barth syndrome. These findings could explain common clinical features observed in Barth syndrome patients such as cardiac arrhythmia and proximal muscle myopathy. In summary, my work shows that yeast phospholipid mutants can be leveraged to uncover specific phospholipid requirements of mitochondrial membrane proteins and suggests a role of mitochondrial calcium signaling in the pathogenesis of Barth syndrome

Power Quality Enhancement through Optimal Reclosing of Circuit Breakers And Thyristor Controlled Capacitor

This thesis aims at enhancing the power quality through an optimal reclosing technique of circuit breakers and power electronics-based controls. A performance comparison among the total kinetic energy based reclosing method, the variable dead time control method, and the total load angle method which is a novel technique proposed in this work, are considered. Simulation results indicate the superiority of the total kinetic energy based reclosing method. The effectiveness of the combined operation of total kinetic energy based optimal reclosing and thyristor controller capacitor is evaluated by considering three indices, namely, voltage index, speed index, and the total harmonic distortion (THD) in case of faults and sudden injection of a large load. Simulation results indicate the effectiveness of the combined operation of the total kinetic energy based reclosing technique and the thyristor-based capacitor. Moreover, the performance of the thyristor-based capacitor is better than that of the thyristor-based resistor or reactor

Minimization of Adverse Effects of Time Delay on Power Quality Enhancement in Hybrid Grid

One of the most challenging issues of the modern power grid is the communication delay, which has adverse effects on the power quality. This paper proposes two methods, such as the fuzzy logic controller (FLC) based approach and the modified predictor method, to minimize the negative effects of time delay on the power quality enhancement in a hybrid power grid consisting of synchronous and wind generators. The thyristor switched capacitor has been used as a power quality enhancement means for the grid. Time delays ranging from 0-700 ms have been considered for the analysis. Both balanced and unbalanced temporary and permanent faults at different locations in the power network have been considered. Two indices, namely the voltage index and the total harmonic distortion have been used to evaluate the power quality of the system. The performance of the FLC-based method has been compared with that of the modified predictor method. Simulations have been performed by using the MATLAB/Simulink software. Simulation results show that both the proposed methods can minimize the negative effects of time delays on the power quality enhancement of the system. However, the FLC method performs better than the modified predictor method

Power quality enhancement by coordinated operation of thyristor switched capacitor and optimal reclosing of circuit breakers

This study proposes a new method of power quality enhancement by using the combined operation of thyristor switched capacitor (TSC) and optimal reclosing of circuit breakers in a multi-machine power network. To evaluate the effectiveness of the proposed method, its performance is compared with that of the combined operation of thyristor-controlled braking resistor (TCBR) and optimal reclosing of circuit breakers. The total kinetic energy-based optimal reclosing method is considered. To analyse the effectiveness of the proposed technique, the IEEE nine-bus power system model is considered. Both balanced and unbalanced temporary and permanent faults at different locations in the power system model are considered. Simulation results demonstrate that the proposed TSC together with the optimal reclosing method performs well. Moreover, the performance of the proposed method is better than that of the combination of TCBR and the optimal reclosing method

Load angle based optimal reclosing technique of circuit breakers for power quality enhancement

This paper proposes a new method of optimal reclosing based on the total load angles of the synchronous gen erators in a multi-machine power system. First the optimal reclosing times are determined, and then the performance of the proposed reclosing method and that of the conventional reclosing technique is compared. In order to analyze the reclosing techniques, the IEEE nine bus power system model is considered. Both balanced and unbalanced temporary and permanent faults at different locations in the power system model are considered. Two indices are considered to evaluate the system performance in terms of power quality enhancement. Simulation results indicate that the proposed total load angles based optimal reclosing technique is effective to maintain the power quality in a multi-machine power system. Moreover, the performance of the proposed reclosing method is better than that of the conventional reclosing method. © 2013 IEEE

Minimization of adverse effects of time delay in smart power grid

Time delay has adverse effects on control systems in an electric power grid. This paper analyzes the cyber-attack related time delay issues, and deals with the minimization of negative effects of such delays in smart gird system. The prediction method has been used to minimize the negative effects of time delay. The OPRT (optimal reclosing time) method to reclose circuit breakers are considered. Time delays of 100ms and 2.2s have been considered. The effectiveness of the proposed method has been tested in the IEEE nine-bus power system model. Both balanced and unbalanced permanent faults are considered. Simulations are performed through Matlab/Simulink software. The performance of the system considering time delays with the predictor and without the predictor has been compared. From the simulation results, it is shown that the proposed predictor performs well in minimizing the negative effects of time delays. © 2014 IEEE