Voltage stability assessment for distrbuted generation in islanded microgrid system

The increasing energy demands are stressing the generation and transmission capabilities of the power system. Distributed generation (DG), which generally located in distribution systems, has the ability to meet some of the growing energy demands. However, unplanned application of individual distributed generators might cause other technical problems. The microgrid concept has the potential to solve major problems arising from large penetration of DG in distribution systems. A microgrid is not a forceful system when it is compared to a power system. This project proposes a simulation approach to study voltage stability index (VSI) and voltage stability analysis in microgrid system for the improvement of the dynamic voltage stability in a microgrid in case of the dynamic voltage insufficiency. A model of IEEE-14 Bus System has been presented as a case study of an islanded microgird system. This project also presented line voltage stability index analysis which accurately performs voltage stability analysis at each transmission line and precisely predicts voltage collapse on power systems. A formula to calculate VSI has been derived and applied on two cases on the system. To show the effectiveness of the proposed voltage stability analysis method, this approach is implemented in a microgrid test system (14-bus, 20 lines) in PSAT which is a MATLAB toolbox environment. The test system has four diesel DGs and a wind turbine connected with eleven constant loads. The dynamic simulation of the test system is carried out for various types of disturbances. Islanded mode of operation is considered in this study. Fast Voltage Stability Index (FVSI) and voltage stability analysis have been successfully implemented and analysed

Observations of Lick Standard Stars Using the SCORPIO Multi-Slit Unit at the SAO 6-m Telescope

We present Lick line-index measurements of standard stars from the list of Worthey. The spectra were taken with the multi-slit unit of the SCORPIO spectrograph at the 6-m Special Astrophysical observatory telescope. We describe in detail our method of analysis and explain the importance of using the Lick index system for studying extragalactic globular clusters. Our results show that the calibration of our instrumental system to the standard Lick system can be performed with high confidence.Comment: 12 pages, 3 figure

A Structural Analysis of Field/Circuit Coupled Problems Based on a Generalised Circuit Element

In some applications there arises the need of a spatially distributed description of a physical quantity inside a device coupled to a circuit. Then, the in-space discretised system of partial differential equations is coupled to the system of equations describing the circuit (Modified Nodal Analysis) which yields a system of Differential Algebraic Equations (DAEs). This paper deals with the differential index analysis of such coupled systems. For that, a new generalised inductance-like element is defined. The index of the DAEs obtained from a circuit containing such an element is then related to the topological characteristics of the circuit's underlying graph. Field/circuit coupling is performed when circuits are simulated containing elements described by Maxwell's equations. The index of such systems with two different types of magnetoquasistatic formulations (A* and T-$\Omega$) is then deduced by showing that the spatial discretisations in both cases lead to an inductance-like element

A STATIC AND DYNAMIC TECHNIQUE CONTINGENCY RANKING ANALYSIS IN VOLTAGE STABILITY ASSESSMENT

The objective of the research is to compare between technique for determine the weak bus of the power system using static and dynamic contingency ranking analysis. Identification of the weak bus is very important for providing a proper control system to prevent for voltage collapse. Test system of this research is using the New England (IEEE 39 bus) power system. A severity ranking of the system is carried out on the study system to specify weak buses, in term of voltage instability. A contingency as a load increment is employed to examine the network buses condition and stability margin in the system. Three methods techniques as eigenvalue analysis of jacobian matrix is used as a static methods and a voltage collapse prediction index, and power transfer stability index as a dynamic methods are investigated. The result showed that the static analysis is giving more optimistic in evaluating loadability limit than dynamic. For the contingency ranking both static and dynamic give same trend in every bus. But for final decisions involving several consideration both planning and operation should be confirm by more accurate time domain simulation (dynamic) in which different characteristics of load, multiple controller, protection relays and coordinated them taken into account Key words: contingency analysis, static and dynamic analysis, voltage stabilit

"Can the neuro fuzzy model predict stock indexes better than its rivals?"

This paper develops a model of a trading system by using neuro fuzzy framework in order to better predict the stock index. Thirty well-known stock indexes are analyzed with the help of the model developed here. The empirical results show strong evidence of nonlinearity in the stock index by using KD technical indexes. The trading point analysis and the sensitivity analysis of trading costs show the robustness and opportunity for making further profits through using the proposed nonlinear neuro fuzzy system. The scenario analysis also shows that the proposed neuro fuzzy system performs consistently over time.

The Method of Construction of Ukrainian Business-system Profile

Under conditions of crisis transformations at the national level, the absence of constant trends of development of economy and business-system as a whole there was carried out the analysis of Ukrainian business-system functioning in the context of 8 world ratings (business doing easiness; rating of national brands; rating of global competitiveness; rating of budget transparence; rating of investment attractiveness; rating of autosorcing attractiveness; index of economic freedoms; index of trade facilitation) that gives a possibility to assess the place of Ukraine in the global conditions of development comparing with the state of business-system development in other countries of the world

Semantic industrial categorisation based on search engine index

Analysis of specialist language is one of the most pressing problems when trying to build intelligent content analysis system. Identifying the scope of the language used and then understanding the relationships between the language entities is a key problem. A semantic relationship analysis of the search engine index was devised and evaluated. Using search engine index provides us with access to the widest database of knowledge in any particular field (if not now, then surely in the future). Social network analysis of keywords collection seems to generate a viable list of the specialist terms and relationships among them. This approach has been tested in the engineering and medical sectors

Prognosis of patients with hepatocellular carcinoma. Validation and ranking of established staging-systems in a large western HCC-cohort.

HCC is diagnosed in approximately half a million people per year, worldwide. Staging is a more complex issue than in most other cancer entities and, mainly due to unique geographic characteristics of the disease, no universally accepted staging system exists to date. Focusing on survival rates we analyzed demographic, etiological, clinical, laboratory and tumor characteristics of HCC-patients in our institution and applied the common staging systems. Furthermore we aimed at identifying the most suitable of the current staging systems for predicting survival. Overall, 405 patients with HCC were identified from an electronic medical record database. The following seven staging systems were applied and ranked according to their ability to predict survival by using the Akaike information criterion (AIC) and the concordance-index (c-index): BCLC, CLIP, GETCH, JIS, Okuda, TNM and Child-Pugh. Separately, every single variable of each staging system was tested for prognostic meaning in uni- and multivariate analysis. Alcoholic cirrhosis (44.4%) was the leading etiological factor followed by viral hepatitis C (18.8%). Median survival was 18.1 months (95%-CI: 15.2-22.2). Ascites, bilirubin, alkaline phosphatase, AFP, number of tumor nodes and the BCLC tumor extension remained independent prognostic factors in multivariate analysis. Overall, all of the tested staging systems showed a reasonable discriminatory ability. CLIP (closely followed by JIS) was the top-ranked score in terms of prognostic capability with the best values of the AIC and c-index (AIC 2286, c-index 0.71), surpassing other established staging systems like BCLC (AIC 2343, c-index 0.66). The unidimensional scores TNM (AIC 2342, c-index 0.64) and Child-Pugh (AIC 2369, c-index 0.63) performed in an inferior fashion. Compared with six other staging systems, the CLIP-score was identified as the most suitable staging system for predicting prognosis in a large German cohort of predominantly non-surgical HCC-patients