This paper proposes a new index to determine the static voltage stability of the load buses in a power network for certain operating conditions and hence identifies load buses which are close to voltage collapse. The proposed index is formulated from the quadratic equation derived from a twobus network and is computed using the apparent power and the line impedance. The proposed index shows how...

Analytic techniques for predicting onset of voltage collapse in power systems often rely upon identification of a saddle node bifurcation. While many authors acknowledge that the separation between voltage phenomena and phase angle phenomena is far from absolute, most recent works have viewed voltage variation as the more significant problem. The goal of the work presented here is to shift focu...

We have investigated the surface morphology of electrically stressed AlGaN/GaN high electron mobility transistors using atomic force microscopy and scanning electron microscopy after removing the gate metallization by chemical etching. Changes in surface morphology were correlated with degradation in electrical characteristics. Linear grooves formed along the gate edges in the GaN cap layer for...

Reliability is one of the key issues for the application of Silicon carbide (SiC) diode in high power conversion systems. For instance, in high voltage direct current (HVDC) converters, the devices can be submitted to high voltage transients which yield to avalanche. This paper presents the experimental evaluation of SiC diodes submitted to avalanche, and shows that the energy dissipation in th...

This paper presents a newly developed approach to find the optimal location of distributed generations (DGs) to improve power system voltage stability margin and reduce losses incorporating the constraints. The loadability limit index is used to assess the static voltage stability security margin, which is associated with the point of voltage collapse limit. Based on this, a toolbox is develope...

Voltage-Source Converters have brought numerous advantages to HVDC transmission. However, they suffer from high losses and are usually weak against faults on the DC-side. In this paper, a new topology which brings together some concepts from traditional Current Source Converters and multi-level converters, is presented. Two stacks of Hbridge cells alternate to construct the converter voltage us...

The objective of this paper is to provide a risk-based approach to security assessment for a voltage stability constrained power system. It is motivated by a perception that today’s deterministic reliability criteria to voltage stability assessment often results in operating restrictions that are not commensurate with the corresponding level of risk. The risk calculation provided in this paper ...

Nigeria power system has been experiencing total or partial failures in recent times and voltage instability is a strong factor. The paper seeks to perform the stability analysis, based on static P-V plots, buses located around within South East zone of Nigeria. An injection group containing generators serve as source sink loads be monitored are created. assumed their min/max MW limits. load in...

The explosive growth in decision-support systems over the past 30 years has yielded numerous “intelligent” systems that have often produced less-than-stellar results (Michalewicz Z. et al., 2005). The increasing trend in developing intelligent systems based on neural networks is attributed to their capability of learning nonlinear problems offline with selective training, which can lead to suff...

Voltage stability has become an important issue in planning and operation of many power systems. Contingencies such as unexpected line outages in a stressed system may often result in voltage instability, which may lead to voltage collapse. This paper presents evolutionary algorithm techniques like Genetic Algorithm (GA) and Non-dominated Sorting Genetic Algorithm II (NSGA II) approach for solv...