Performance evaluation of multiquadrant DC drive using fuzzy- genetic approach

This paper presents the simulation of multiquadrant DC drive using Fuzzy Logic Control (FLC) for various operating conditions. Genetic Algorithm (GA) has been used in the design of membership functions and rule sets for eliminating the need of human input in the design loop. Performance analysis is performed through mathematical simulation for the stable operation of the drive. Simulated results validate the proposed control techniqu

Electric power demand forecasting: A case study of Lucknow city

The study of forecasting identifies the urgent need for special attention in evolving effective energy policies to alleviate an energy famine in the near future. Since power demand is increasing day by day in entire world and it is also one of the fundamental infrastructure input for the development, its prospects and availability sets significant constraints on the socio-economic growth of every person as well as every country. A care full long-term power plan is imperative for the development of power sector. This need assumes more importance in the state of Uttar Pradesh where the demand for electrical energy is growing at a rapid pace. This study analyses the requirement of electricity with respect to the future population for the major forms of energy in the Lucknow city in Uttar Pradesh state of India. A model consisting of significant key energy indicators have been used for the estimation. Model wherever required refined in the second stage to remove the effect of auto-correlation. The accuracy of the model has been checked using standard statistical techniques and validated against the past data by testing for 'expost' forecast accuracy

Studies in Mixed Adsorbent Systems: Adsorption of Water Vapours on Carbogels

105-11

Reliability evaluation of power system considering voltage stability and continuation power flow

This article describes the methodology for evaluation of the reliability of an composite electrical power system considering voltage stability and continuation power flow, which takes into account the peak load and steady state stability limit. The voltage stability is obtained for the probable outage of transmission lines and removal of generators along with the combined state probabilities. The loss of load probabilities (LOLP) index is evaluated by merging the capacity probability with load model. State space is truncated by assuming the limits on total numbers of outages of generators and transmission lines. A prediction correction technique has been used along with one dimensional search method to get optimized stability limit for each outage states. The algorithm has been implemented on a six-bus test system

Voltage Stability Analysis of Grid-Connected Wind Farms with FACTS: Static and Dynamic Analysis

Recently, analysis of some major blackouts and failures of power system shows that voltage instability problem has been one of the main reasons of these disturbances and networks collapse. In this paper, a systematic approach to voltage stability analysis using various techniques for the IEEE 14-bus case study, is presented. Static analysis is used to analyze the voltage stability of the system under study, whilst the dynamic analysis is used to evaluate the performance of compensators. The static techniques used are Power Flow, V–P curve analysis, and Q–V modal analysis. In this study, Flexible Alternating Current Transmission system (FACTS) devices- namely, Static Synchronous Compensators (STATCOMs) and Static Var Compensators (SVCs) - are used as reactive power compensators, taking into account maintaining the violated voltage magnitudes of the weak buses within the acceptable limits defined in ANSI C84.1. Simulation results validate that both the STATCOMs and the SVCs can be effectively used to enhance the static voltage stability and increasing network loadability margin. Additionally, based on the dynamic analysis results, it has been shown that STATCOMs have superior performance, in dynamic voltage stability enhancement, compared to SVCs

Hybrid fuzzy particle swarm optimization approach for reactive power optimization

This paper presents a new approach to the optimal reactive power planning based on fuzzy logic and particle swarm optimization (PSO). The objectives are to minimize real power loss and to improve the voltage profile of a given interconnected power system. Transmission loss is expressed in terms of voltage increments by relating the control variables i.e. reactive var generations by the generators, tap positions of transformers and reactive power injections by the shunt capacitors. The objective function and the constraints are modeled by fuzzy sets. A term ‘sensitivity’ at each bus is defined which depends on variation of real power loss with respect to the voltage at that bus. Based on the Fuzzy membership values of the sensitivity, corrective action at a particular bus is taken i.e. shunt capacitors are installed at the candidate buses based on real power loss and sets of solution. Then, PSO is applied to get final solution. PSO is used for optimal setting of transformer tap positions and reactive generations of generators. The solutions obtained by this method is compared with the solutions obtained by other evolutionary algorithms like genetic algorithm (GA), differential evolution (DE) and particle swarm optimization (PSO)

Some issues related to power generation using wind energy conversion systems: An overview

Design and successful operation of wind energy conversion systems (WECs) is a very complex task and requires the skills of many interdisciplinary skills, e.g., civil, mechanical, electrical and electronics, geography, aerospace, environmental etc. Performance of WECs depends upon subsystems like wind turbine (aerodynamic), gears (mechanical), generator (electrical); whereas the availability of wind resources are governed by the climatic conditions of the region concerned for which wind survey is extremely important to exploit wind energy. This paper presents a number of issues related to the power generation from WECs e.g. factors affecting wind power, their classification, choice of generators, main design considerations in wind turbine design, problems related with grid connections, wind-diesel autonomous hybrid power systems, reactive power control of wind system, environmental aspects of power generation, economics of wind power generation, and latest trend of wind power generation from off shore sites

Extended excitons and compact heliumlike biexcitons in type-II quantum dots.

We have used magneto-photoluminescence measurements to establish that InP/GaAs quantum dots have a type-II band (staggered) alignment. The average excitonic Bohr radius and the binding energy are estimated to be 15 nm and 1.5 meV respectively. When compared to bulk InP, the excitonic binding is weaker due to the repulsive (type-II) potential at the hetero-interface. The measurements are extended to over almost six orders of magnitude of laser excitation powers and to magnetic fields of up to 50 tesla. It is shown that the excitation power can be used to tune the average hole occupancy of the quantum dots, and hence the strength of the electron-hole binding. The diamagnetic shift coe±cient is observed to drastically reduce as the quantum dot ensemble makes a gradual transition from a regime where the emission is from (hydrogen-like) two-particle excitonic states to a regime where the emission from (helium-like) four-particle biexcitonic states also become significant

Size, shape and surface chemistry of nano-gold dictate its cellular interactions, uptake and toxicity

Colloidal gold is undoubtedly one of the most extensively studied nanomaterials, with 1000s of different protocols currently available to synthesise gold nanoparticles (AuNPs). While developments in the synthesis of AuNPs have progressed rapidly in recent years, our understanding of their biological impact, with particular respect to the effect of shape, size, surface characteristics and aggregation states, has struggled to keep pace. It is generally agreed that when AuNPs are exposed to biological systems, these parameters directly influence their pharmacokinetic and pharmacodynamic properties by influencing AuNPs distribution, circulation time, metabolism and excretion in biological systems. However, the rules governing these properties, and the science behind them, are poorly understood. Therefore, a systematic understanding of the implications of these variables at the nano-bio interface has recently become a topic of major interest. This Review Article attempts to ignite a discussion around the influence of different physico-chemical parameters on biological activity of AuNPs, while focussing on critical aspects of cellular interactions, uptake and cytotoxicity. The review also discusses emerging trends in AuNP uptake and toxicity that are leading to technological advances through AuNP-based therapy, diagnostics and imaging

A New Simulation Metric to Determine Safe Environments and Controllers for Systems with Unknown Dynamics

We consider the problem of extracting safe environments and controllers for reach-avoid objectives for systems with known state and control spaces, but unknown dynamics. In a given environment, a common approach is to synthesize a controller from an abstraction or a model of the system (potentially learned from data). However, in many situations, the relationship between the dynamics of the model and the \textit{actual system} is not known; and hence it is difficult to provide safety guarantees for the system. In such cases, the Standard Simulation Metric (SSM), defined as the worst-case norm distance between the model and the system output trajectories, can be used to modify a reach-avoid specification for the system into a more stringent specification for the abstraction. Nevertheless, the obtained distance, and hence the modified specification, can be quite conservative. This limits the set of environments for which a safe controller can be obtained. We propose SPEC, a specification-centric simulation metric, which overcomes these limitations by computing the distance using only the trajectories that violate the specification for the system. We show that modifying a reach-avoid specification with SPEC allows us to synthesize a safe controller for a larger set of environments compared to SSM. We also propose a probabilistic method to compute SPEC for a general class of systems. Case studies using simulators for quadrotors and autonomous cars illustrate the advantages of the proposed metric for determining safe environment sets and controllers.Comment: 22nd ACM International Conference on Hybrid Systems: Computation and Control (2019