This article proposes a new method to increase a power system's security margin and/or support its low voltage buses by re-dispatching generator outputs, using a normal vector found at a voltage collapse boundary or a low voltage boundary (LVB). This method uses the normal vector as an indicator to change the generation direction so that more power can be transferred before reaching a boundary ...

The static voltage stability and the dynamic voltage stability are integrated. To consider a shunt compensator and/or a more general load which is dependent on voltage, a modified criterion for the static voltage stability is developed and the system is controlled to satisfy this static Stability criterion. For an accurate analysis of the dynamic voltage stability, the system model includes exc...

We report experimental results from collapsed regime operation of capacitive micromachined ultrasonic transducers (cMUTs) fabricated by a wafer bonding technique. The results show that a cMUT operating in the collapsed regime produces a maximal output pressure higher than a cMUT operating in the precollapse regime at 90 % of its collapse voltage, 1.79 kPa/V vs. 9.72 kPa/V at 2.3 MHz. In collaps...

Loading margin is a fundamental measure of proximity to voltage collapse. Linear and quadratic estimates to the variation of the loading margin with respect to any system parameter or control are derived. Tests with a 118 bus system indicate that the estimates accurately predict the quantitative effect on the loading margin of altering the system loading, reactive power support, wheeling, load ...

We report a low current collapse GaN-based high electron mobility transistor (HEMT) with an excellent thermal stability at 150 °C. The AlN was grown by N2-based plasma enhanced atomic layer deposition (PEALD) and shown a refractive index of 1.94 at 633 nm of wavelength. Prior to deposit AlN on III-nitrides, the H2/NH3 plasma pre-treatment led to remove the native gallium oxide. The X-ray photoe...

The intrinsic mechanisms of drain lag and current collapse in GaN-based high-electron-mobility transistors are studied by using two-dimensional numerical simulations. Simulated drain lag characteristics are in good agreement with reported experimental data. The dynamic pictures of trapping of hot electrons under drain-pulse voltages are discussed in detail. Hot-electron buffer-trapping effect p...

Voltage collapse; Sequential quadratic programming; FACTS devices; Voltage security margin; Optimal continuous power flow. Abstract In this paper, an effective method is presented to determine the security margin against voltage collapse, and improve it by means of FACTS devices in the optimal continuous power flow framework. The primary methods for determining the system’s critical states of v...

Many power engineering systems have dynamic state variables which can encounter constraints or limits affecting system stability. Voltage collapse is an instability associated with the occurrence of a saddle node bifurcation in the equations which model the electric power system. We investigate the effect of constraints on voltage collapse by studying the effect of constraining state variables ...

A complete electrical characterization of different types of GaAs field effect transistors at liquid nitrogen temperature is performed. The trapping-detrapping mechanisms on deep levels are particularly adressed and a method is proposed to circumvent the collapse phenomenom which otherwise limits the electrical performances. From these measurements a HEMT non-linear model is extracted and is fo...

The purpose of this paper is to study the description of power system QV curves by using the method of fuzzy modeling for analysis of voltage stability. Voltage instability of power system comes from increasing load rapidly, and causes bus voltage to drop. When voltage is out of control and it can be voltage collapse. The QV curve can identify voltage stability limit, and it determine robustnes...