Showing 3 results for Voltage Stability
M.e. Hamedani Golshan, H. Ghoudjehbaklou and H. Seifi,
Volume 20, Issue 2 (4-2001)
Abstract
Finding the collapse susceptible portion of a power system is one of the purposes of voltage stability analysis. This part which is a voltage control area is called the voltage weak area. Determining the weak area and adjecent voltage control areas has special importance in the improvement of voltage stability. Designing an on-line corrective control requires the voltage weak area to be determined by a sufficiently rapid and precise method. In this paper, a new algorithm based on assigning a vector to
each power system bus is presented. These vectors indicate buses conditions from the viewpoint of voltage stability. In this new method, using the clustering methods such as kohonen neural network, fuzzy C-Means algorithm and fuzzy kohonen algorithm, voltage control areas are determined The proposed method has advantages such as determining PV and PQ buses which belong to the weak area simultanously, under all operating conditions and without a need to system model. Also by comparing the results of applying clustering methods, it has been observed that, due to simplicity of implementation and precision of the results, the two dimensional kohonen neural network is a more suitable tool for clustering power system to voltage control areas than the fuzzy C-Means and fuzzy kohonen methods.
Keywords: Voltage stability, Voltage weak area, Voltage control area, Corrective control, Pattern recognition, Kohonen neural network, Fuzzy C-Means algorithm, Fuzzy Kohonen algorithm.
Gh. Yousefi, H.seifi and M. S. Ghazi-Zadeh,
Volume 21, Issue 1 (7-2002)
Abstract
In a de-regulated open access environment, reactive power is one of the ancillary services which must be provided by an Independent System Operator (ISO). In this paper, a new algorithm is proposed in which reactive power resources are initially so tuned that optimum security in terms of voltage profile and voltage stability are achieved while at the same time, the system losses are minimized. The resulting optimization case is solved as an Extended Multi-objective Optimal Power Flow (EMOPF) problem using Lexico Graphic Method (LGM). Thereafter, using the concept of Fair Resource Allocation (FRA), the reactive powers generated are distributed among existing transactions so that the costs incurred are properly and fairly recovered. The algorithm is successfully tested on a typical power system.
Keywords: Reactive Power, Reactive Power Management, Reactive Power Pricing, Voltage Profile, Voltage Stability, Deregulated Environment, Open Access
M. Eidiani, M. H. Modir Shanechi and E. Vaahedi,
Volume 23, Issue 2 (1-2005)
Abstract
Methods for calculating Available Transfer Capability (ATC) of the transmission systems may be grouped under Static and Dynamic methods. This paper presents a fast dynamic method for ATC calculations, which considers both Transient Stability Limits and Voltage Stability Limits as terminating criteria. A variation of Energy Function Method is used to determine the transient stability limit and the determinant of the Jacobian matrix of the system is used as an index to determine the voltage stability limit. A novel method is used to approximately calculate this determinant. Combining these two methods, an algorithm that calculates ATC, based on both voltage and angle dynamic stability is presented. The advantage of this algorithm, besides considering both voltage and angle dynamic stability, is its high speed. This speed of calculation makes the algorithm a perfect
candidate to be used in screening contingencies and to determine those cases that need to be further analyzed. To demonstrate the validity, efficiency, and the speed of the new method, it is employed in the calculation of ATC for numerical examples with 2, 3, 7 (CIGREE), 10, 30 (IEEE) and 145 (Iowa State) buses.
