Tabu Search Based Algorithm for Multi-Objective Network Reconfiguration Problem

Abstract: The electric power distribution usually operates in a radial configuration, with tie switches between circuits to provide alternate feeds. The losses would be minimized if all switches were closed, but this is not done because it complicates the system’s protection against over currents. Whenever components fail, some of the switches must be operated to restore power to as many customers as possible. As loads vary with time, switch operations may reduce losses in the system. All of these are applications for reconfiguration. The reconfiguration problem is combinatorial problem, which precludes algorithms that guarantee a global optimum. Most existing reconfiguration algorithms fall into two categories. In the first, branch exchange, the system operates in a feasible radial configuration and the algorithm opens and closes candidate switches in pairs. In the second, loop cutting, the system is completely meshed and the algorithm opens candidate switches to reach a feasible radial configuration. Reconfiguration algorithms based on neural network, heuristics, genetic algorithms, and simulated annealing have also been reported, but not widely used. The objective of the paper presented in this work is to make a Tabu Search (TS) based algorithm for multi-objective programming to solve the network reconfiguration problem in a radial distribution system. Here six objectives are considered in conjunction with network constraints. The main objective of research is allocation of optimal switches to reduce the power losses of the system. It is tested for 33 bus systems. Simulation results of the case studies demonstrate the effectiveness of the solution algorithm and proved that the TS is suitable to solve this kind of problems. Key words: Combinatorial optimization; Distribution system; Energy Loss minimization; Genetic Algorithm; Simulating Annealing; Tabu searc

A novel load shedding methodology to mitigate voltage instability in power system

Aim. A novel technique for detecting imminent voltage instability is proposed in this paper, accompanied by a novel load shedding approach to protect the system from voltage instability. Methodology. The proposed methodology utilizes the computation of nodal reactive power loss to voltage sensitivities with load increments in the system. Originality. The nodal reactive power loss to voltage sensitivity is a novel computation and is explored to detect the likelihood of voltage instability in this work. Results. If the system is experiencing an unprecedented load growth and if all the measures reach their limits, then load shedding is the last resort to safeguard the system against instability. The sudden change in nodal reactive power loss to voltage sensitivities is utilized to devise the quantity of load to be cut in the system. Practical value. The time-based simulations performed in New England 39 bus test system (NE-39 bus), the simulated results show that nodal reactive power loss to voltage sensitivities can be used as a trusted indicator for early diagnosing of menacing voltage instability and the timely implementation of load shedding developed from nodal reactive power loss to voltage sensitivities on the system ensures voltage stability.Мета. У статті пропонується новий метод виявлення навислої нестабільності напруги, що супроводжується новим підходом до скидання навантаження для захисту системи від нестабільності напруги. Методологія. У запропонованій методиці використовується розрахунок вузлових втрат реактивної потужності залежно від чутливості до напруги при збільшенні навантаження у системі. Оригінальність. У цій роботі вузлові втрати реактивної потужності залежно від чутливості до напруги являють собою новий розрахунок і досліджуються визначення ймовірності нестабільності напруги. Результати. Якщо система відчуває безпрецедентне зростання навантаження і всі заходи досягають меж своїх можливостей, скидання навантаження є останнім засобом захисту від нестабільності. Раптова зміна вузлових втрат реактивної потужності, залежно від чутливості до напруги, використовується для визначення величини навантаження, яка повинна бути відсічена в системі. Практична цінність. Моделювання, засноване на часі, виконане в тестовій системі шини New England 39 (шина NE-39), та результати моделювання показують, що залежність вузлових втрат реактивної потужності від чутливості до напруги може використовуватися як надійний індикатор для ранньої діагностики загрозливої нестабільності напруги та своєчасного впровадження скидання навантаження, що виникає внаслідок втрати реактивної потужності у вузлах, до чутливості системи до напруги,а забезпечує стабільність напруги

25 years of the UK EIA System: Strengths, weaknesses, opportunities and threats

This paper offers a review of the UK EIA system, providing insights into its evolution and reflecting on perceptions of effectiveness of the EIA system. The work adopts a similar approach used by Glasson in 1999, where he provided a review of the first 10 years of EIA in the UK, complimented by a SWOT analysis. In conducting the SWOT analysis, the authors make use of (1) a UK EIA survey which was conducted in 2011; (2) an interactive session organised at a 2013 workshop at the University of Liverpool on 25 years of the EU EIA Directive; and (3) a systematic literature review of publications since 1999. The results indicate that the internal factors (i.e. strengths and weaknesses) of the EIA system have not actually changed much in the last 15 years. Changes are more apparent for the external factors, especially with regards to opportunities. However, EIA may be suffering from a mid-life crisis at this point and a lot may be owing to perceptions towards EIA which may be influenced and inversely related to the length of experience in EIA. This opens up avenues for further research in the area

Design and development of subsoiler-cum-differential rate fertilizer applicator

A subsoiler-cum-differential rate fertilizer applicator was designed and developed by selecting the best parameters from previous studies.  The equipment consisted of a rectangular frame, a main winged tine, two shallow leading winged tines, a depth control device, a fertilizer box of 100 kg capacity, positive feed type fertilizer metering devices and a ground wheel with chain and sprockets for transmitting power to the metering mechanism.  The equipment had the option to place fertilizers up to a 500 mm soil depth by the main winged tine and delivering fertilizer up to 250 mm deep using the leading tines, thereby helping place fertilizer at different depths in vertical soil profile in a single pass.  All three tines had independent metering systems.  Options were provided to meter and deliver either 33.3% or 25.0% or 20.0% of the total recommended fertilizers with the main tine and the remaining amount through two shallow leading tines.  The laboratory evaluations indicated a coefficient of uniformity of more than 90% for application rates of 250, 500, 750 and 1,000 kg/ha.  The equipment was tested in the field to observe its performance on sugarcane with results showing an increase of 16.2%, 16.4% and 35.4% in yield as compared to conventional ploughing with in-furrow fertilizer application (Control).  Subsoiling alone increased the cane weight, number of millable cane and cane yield by 4.3%, 11.4% and 15.9% compared to the control.Keywords: Subsoiling, differential rate fertilizer placement, sugarcane Citation: Mandal S., and T. C. Thakur.  Design and development of subsoiler-cum-differential rate fertilizer applicator. Agric Eng Int: CIGR Journal, 2010, 12(1): 74-83

Institutions and Performance of Regulated Firms: Evidence from Electric Utilities in the Indian States

It is commonly accepted that institutions influence economic development of countries. But, can we also trace the effect of institutional endowment to specific sectors and regions of a country? There is a significant gap in knowledge and evidence of this issue in the literature. This paper examines this effect in the Indian electricity distribution sector and explores the influence of state-level institutional quality and economic factors on the performance of network utilities in India. Since the 1990s, India has adopted reform steps to improve the efficiency of its electricity sector. However, there remain performance differences among the utilities. We examine the performance of 52 electricity distribution utilities in 24 Indian states for the period from 2006-07 to 2011-12. The findings confirm that the quality of institutions and state-wide economic development affect the performance of the electricity distribution utilities in different states. Additionally, we simulate the cost savings from utilities� performance improvements linked with institutional enhancements. The results indicate the need to strengthen the institutions, for example through regulatory agencies reform to improve the performance of the sector

Neuromorphic In-Memory Computing Framework using Memtransistor Cross-bar based Support Vector Machines

This paper presents a novel framework for designing support vector machines (SVMs), which does not impose restriction on the SVM kernel to be positive-definite and allows the user to define memory constraint in terms of fixed template vectors. This makes the framework scalable and enables its implementation for low-power, high-density and memory constrained embedded application. An efficient hardware implementation of the same is also discussed, which utilizes novel low power memtransistor based cross-bar architecture, and is robust to device mismatch and randomness. We used memtransistor measurement data, and showed that the designed SVMs can achieve classification accuracy comparable to traditional SVMs on both synthetic and real-world benchmark datasets. This framework would be beneficial for design of SVM based wake-up systems for internet of things (IoTs) and edge devices where memtransistors can be used to optimize system's energy-efficiency and perform in-memory matrix-vector multiplication (MVM).Comment: 4 pages, 5 figures, MWSCAS 201

A new voltage instability detection index based on real-time synchronophasor measurements

This paper demonstrates the performance of the Reactive Power Loss Based Voltage Instability Detection Index (QLVIDI), previously introduced in [1], under various testing conditions applied to the New England 39 bus test system using time-based simulations in the Power System Analysis Toolbox (PSAT) in MATLAB. The proposed scheme calculates an instantaneous time series of reactive power losses taking into account the direction of active power flow in every node in the system by considering the reactive power limits of the generators. This time series data is then used to evaluate a cumulative reactive power loss and the degree of deviation from the base case loss for developing QLVIDI. The effectiveness of the proposed index in early detection of imminent voltage collapse scenarios has been tested in various cases and also compared with already existing Improved voltage instability monitoring index(IVIMI)

Superconductivity in correlated disordered two-dimensional electron gas

We calculate the dynamic effective electron-electron interaction potential for a low density disordered two-dimensional electron gas. The disordered response function is used to calculate the effective potential where the scattering rate is taken from typical mobilities from recent experiments. We investigate the development of an effective attractive pair potential for both disordered and disorder free systems with correlations determined from existing numerical simulation data. The effect of disorder and correlations on the superconducting critical temperature Tc is discussed.Comment: 4 pages, RevTeX + epsf, 4 figure

Consumptive hypothyroidism: an unusual paraneoplastic manifestation of a gastric gastrointestinal stromal tumor

A 42-year-old hypothyroid shepherd presented with a progressive abdominal lump accompanied by nausea and abdominal fullness. In addition, he had worsening hypothyroidism, despite supranormal doses of thyroxine. Computed tomography of the abdomen was suggestive of a mass lesion in relation to the stomach. A resection of the mass was done and the histopathology was suggestive of gastrointestinal stromal tumor. After surgery, the patient became euthyroid. We believe the patient had consumptive hypothyroidism due to the tumor