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

A Generalized Index for Static Voltage Stability of Unbalanced Polyphase Power Systems including Th\'evenin Equivalents and Polynomial Models

This paper proposes a Voltage Stability Index (VSI) suitable for unbalanced polyphase power systems. To this end, the grid is represented by a polyphase multiport network model (i.e., compound hybrid parameters), and the aggregate behavior of the devices in each node by Th\'evenin Equivalents (TEs) and Polynomial Models (PMs), respectively. The proposed VSI is a generalization of the known L-index, which is achieved through the use of compound electrical parameters, and the incorporation of TEs and PMs into its formal definition. Notably, the proposed VSI can handle unbalanced polyphase power systems, explicitly accounts for voltage-dependent behavior (represented by PMs), and is computationally inexpensive. These features are valuable for the operation of both transmission and distribution systems. Specifically, the ability to handle the unbalanced polyphase case is of particular value for distribution systems. In this context, it is proven that the compound hybrid parameters required for the calculation of the VSI do exist under practical conditions (i.e., for lossy grids). The proposed VSI is validated against state-of-the-art methods for voltage stability assessment using a benchmark system which is based on the IEEE 34-node feeder

Optimized Solar Photovoltaic Generation in a Real Local Distribution Network

Remarkable penetration of renewable energy in electric networks, despite its valuable opportunities, such as power loss reduction and loadability improvements, has raised concerns for system operators. Such huge penetration can lead to a violation of the grid requirements, such as voltage and current limits and reverse power flow. Optimal placement and sizing of Distributed Generation (DG) are one of the best ways to strengthen the efficiency of the power systems. This paper builds a simulation model for the local distribution network based on obtained load profiles, GIS information, solar insolation, feeder and voltage settings, and define the optimization problem of solar PVDG installation to determine the optimal siting and sizing for different penetration levels with different objective functions. The objective functions include voltage profile improvement and energy loss minimization and the considered constraints include the physical distribution network constraints (AC power flow), the PV capacity constraint, and the voltage and reverse power flow constraints.Comment: To be published (Accepted) in: Proceedings of the IEEE PES Innovative Smart Grid Technologies Conference (ISGT), Washington D.C., USA, 201

Extended measurement of an information system's performance

TUsing Neptun as our scholar information system our everyday experience is that it has some annoying problems even today. Some of them are ergonomic, some of them are technical, others have theoretical roots. Perhaps the most annoying of these problems is that that it is usually too slow. This slowness can be very disappointing especially at the beginning of the examination term and at the registration period. In this paper I describe the circumstances of a measurement which shows that much better performance can be reached based on a good data model even in a poorer working environment and even in case of more serious demands.database efficiency, scholar information system