Active filtering of electric power has now become a mature technology for harmonic and reactive power compensation in two-wire (single phase), three-wire (three phase without neutral), and four-wire (three phase with neutral) AC power networks with nonlinear loads. This paper presents a comprehensive review of active filter (AF) configurations, control strategies, selection of components, other related economic and technical considerations, and their selection for specific applications. It is aimed at providing a broad perspective on the status of AF technology to researchers and application engineers dealing with power quality issues. A list of more than 200 research publications on the subject is also appended for a quick reference.

A review of active filters for power quality improvement

http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

This paper presents an optimal power management mechanism for grid connected photovoltaic (PV) systems with storage. The objective is to help intensive penetration of PV production into the grid by proposing peak shaving service at the lowest cost. The structure of a power supervisor based on an optimal predictive power scheduling algorithm is proposed. Optimization is performed using Dynamic Programming and is compared with a simple ruled-based management. The particularity of this study remains first in the consideration of batteries ageing into the optimization process and second in the “day-ahead” approach of power management. Simulations and real conditions application are carried out over one exemplary day. In simulation, it points out that peak shaving is realized with the minimal cost, but especially that power fluctuations on the grid are reduced which matches with the initial objective of helping PV penetration into the grid. In real conditions, efficiency of the predictive schedule depends on accuracy of the forecasts, which leads to future works about optimal reactive power management.

Optimal Power Flow Management for Grid Connected PV Systems With Batteries

With the fast-paced changing technologies in the power industry, new power references addressing new technologies are coming to the market. So there is an urgent need to keep track of international experiences and activities taking place in the field of modern unit-commitment (UC) problem. This paper gives a bibliographical survey, mathematical formulations, and general backgrounds of research and developments in the field of UC problem for past 35 years based on more than 150 published articles. The collected literature has been divided into many sections, so that new researchers do not face any difficulty in carrying out research in the area of next-generation UC problem under both the regulated and deregulated power industry.

Unit commitment-a bibliographical survey

The hydrogen-fueled internal combustion engine : a technical review.

Reactive power generation by grid-tied photovoltaic (PV) inverters is becoming an important subject for both academia and the electric utility industry. This paper reviews the PV inverter VAR generation capability and availability using the concept of power generation duration curve (PGDC), and proposed VAR control methodologies. The impact of a moderate level of PV penetration on a local distribution feeder using actual load and weather data is then evaluated in terms of the necessary reactive power generation by such PV systems in order to restore the operating power factor of the feeder. It was determined that simple local control of the inverters using a combination of constant kVA and constant power factor during the some parts of the days of summer provides satisfactory restoration of initial feeder operating power factor.

Local load power factor correction by grid-interactive PV inverters

This article investigates the characteristics of a pure residential load through field tests. Staged voltage perturbations by station transformer tap-changing are induced both with and without switching ON the feeder shunt capacitors. Sudden voltage deviations by capacitor switching are attempted. Static load parameters are derived from the recorded load response to voltage variations. It is found that the load real and reactive powers can be respectively approximated by a linear and a quadratic function of voltage.

Determination of static load models from LTC and capacitor switching tests

This paper evaluates the performance of a 1 kW bifacial grid-connected PV system. The array is mounted vertically facing west on a building roof for the purpose of generating power during the late afternoon hours, thus assisting with peak load demand. Simulated solar irradiance received by both sides of the array and power production are compared to measured values. The need for better models to estimate diffuse and reflected radiation for bifacial PV studies is addressed. The impact of shading caused by module frame design on the daily array power generation curve is analyzed.

Modeling and analysis of a bifacial grid-connected photovoltaic system

A fast and accurate algorithm for determining induction-motor transient behavior is presented. The fast components of the stator transients are decoupled from the machine flux linkage equations by a linear transformation. The resulting differential equations are then solved by using recursive algebraic equations, which require considerably less computational effort than existing methods. An example shows that the method is very accurate and yet uses less than 40% of the CPU time required by the exact model. The method could be useful in studies that involve simultaneous responses of many machines, such as power system stability studies, where optimal computational efficiency is desirable. >

A fast recursive solution for induction motor transients

An optimal method to control the speed of a wound-rotor induction motor by variable external rotor impedance is presented. The rotor impedance is adjusted so that, for any desired torque and slip values, the total copper losses are minimized. Motor efficiency is improved compared with the case of conventional speed control by variable rotor resistance only. An example illustrates the copper loss reduction and dynamic behavior of the drive. Simulation study results that show the percentage copper loss reduction is generally likely to be higher for lighter loads. For constant-torque loads, the reduction percentage reaches a peak at the lower slip values, whereas for fan-type loads the most significant percentage copper-loss reduction occurs at both the higher and lower slip values. The response time of the rotor speed for startup or a sudden change in the speed setting is considerably smaller than that achieved by pure rotor resistance control. >

Yahia Baghzouz

Papers

Local load power factor correction by grid-interactive PV inverters

Determination of static load models from LTC and capacitor switching tests

Modeling and analysis of a bifacial grid-connected photovoltaic system

A fast recursive solution for induction motor transients

Optimal efficiency speed control of induction motors by variable rotor impedance