Abstract: Crosstalk is the major limiting issue in very high bit-rate digital subscriber line (VDSL) systems in terms of bit-rate or service coverage. At the central office side, joint signal processing accompanied by appropriate power allocation enables complex multiuser processors to provide near capacity rates. Unfortunately complexity grows with the square of the number of lines within a binder, so by taking into account that there are only a few dominant crosstalkers who contribute to main part of crosstalk power, the canceller structure can be simplified which resulted in a much lower run-time complexity. In this paper, a multiuser power control scheme, namely iterative waterfilling, is combined with previously proposed partial crosstalk cancellation approaches to demonstrate the best ever achieved performance which is verified by simulation results.
Abstract: A closed-loop controlled wireless power transmission circuit block for implantable biomedical applications is described in this paper. The circuit consists of one front-end rectifier, power management sub-block including bandgap reference and low drop-out regulators (LDOs) as well as transmission power detection / feedback circuits. Simulation result shows that the front-end rectifier achieves 80% power efficiency with 750-mV single-end peak-to-peak input voltage and 1.28-V output voltage under load current of 4 mA. The power management block can supply 1.8mA average load current under 1V consuming only 12μW power, which is equivalent to 99.3% power efficiency. The wireless power transmission block described in this paper achieves a maximum power efficiency of 80%. The wireless power transmission circuit block is designed and implemented using UMC 65-nm CMOS/RF process. It occupies 1 mm × 1.2 mm silicon area.
Abstract: In this paper a new maximum power point tracking
algorithm for photovoltaic arrays is proposed. The algorithm detects
the maximum power point of the PV. The computed maximum
power is used as a reference value (set point) of the control system.
ON/OFF power controller with hysteresis band is used to control the
operation of a Buck chopper such that the PV module always
operates at its maximum power computed from the MPPT algorithm.
The major difference between the proposed algorithm and other
techniques is that the proposed algorithm is used to control directly
the power drawn from the PV.
The proposed MPPT has several advantages: simplicity, high
convergence speed, and independent on PV array characteristics. The
algorithm is tested under various operating conditions. The obtained
results have proven that the MPP is tracked even under sudden
change of irradiation level.
Abstract: This paper presents the study of a variable speed wind
energy conversion system based on a Doubly Fed Induction Generator
(DFIG) based on a sliding mode control applied to achieve control of
active and reactive powers exchanged between the stator of the DFIG
and the grid to ensure a Maximum Power Point Tracking (MPPT) of
a wind energy conversion system. The proposed control algorithm is
applied to a DFIG whose stator is directly connected to the grid and
the rotor is connected to the PWM converter. To extract a maximum
of power, the rotor side converter is controlled by using a stator
flux-oriented strategy. The created decoupling control between active
and reactive stator power allows keeping the power factor close to
unity. Simulation results show that the wind turbine can operate at
its optimum energy for a wide range of wind speed.
Abstract: Load forecasting has become in recent years one of the major areas of research in electrical engineering. Most traditional forecasting models and artificial intelligence neural network techniques have been tried out in this task. Artificial neural networks (ANN) have lately received much attention, and a great number of papers have reported successful experiments and practical tests. This article presents the development of an ANN-based short-term load forecasting model with improved generalization technique for the Regional Power Control Center of Saudi Electricity Company, Western Operation Area (SEC-WOA). The proposed ANN is trained with weather-related data and historical electric load-related data using the data from the calendar years 2001, 2002, 2003, and 2004 for training. The model tested for one week at five different seasons, typically, winter, spring, summer, Ramadan and fall seasons, and the mean absolute average error for one hour-ahead load forecasting found 1.12%.
Abstract: The impact of fixed speed squirrel cage type as well as
variable speed doubly fed induction generators (DFIG) on dynamic
performance of a multimachine power system has been investigated.
Detailed models of the various components have been presented and
the integration of asynchronous and synchronous generators has been
carried out through a rotor angle based transform. Simulation studies
carried out considering the conventional dynamic model of squirrel
cage asynchronous generators show that integration, as such, could
degrade to the AC system performance transiently. This article
proposes a frequency or power controller which can effectively
control the transients and restore normal operation of fixed speed
induction generator quickly. Comparison of simulation results
between classical cage and doubly-fed induction generators indicate
that the doubly fed induction machine is more adaptable to
multimachine AC system. Frequency controller installed in the DFIG
system can also improve its transient profile.
Abstract: SEMG (Surface Electromyogram) is one of the
bio-signals and is generated from the muscle. And there are many
research results that use forearm EMG to detect hand motions. In this
paper, we will talk about our developed the robot hand system that can
control grasping power by SEMG. In our system, we suppose that
muscle power is proportional to the amplitude of SEMG. The power is
estimated and the grip power of a robot hand is able to be controlled
using estimated muscle power in our system. In addition, to perform a
more precise control can be considered to build a closed loop feedback
system as an object to a subject to pressure from the edge of hand. Our
objectives of this study are the development of a method that makes
perfect detection of the hand grip force possible using SEMG patterns,
and applying this method to the man-machine interface.
Abstract: In this study, a fuzzy-logic based control system was
designed to ensure that time and energy is saved during the operation
of load elevators which are used during the construction of tall
buildings. In the control system that was devised, for the load
elevators to work more efficiently, the energy interval where the
motor worked was taken as the output variable whereas the amount
of load and the building height were taken as input variables. The
most appropriate working intervals depending on the characteristics
of these variables were defined by the help of an expert. Fuzzy expert
system software was formed using Delphi programming language. In
this design, mamdani max-min inference mechanism was used and
the centroid method was employed in the clarification procedure. In
conclusion, it is observed that the system that was designed is
feasible and this is supported by statistical analyses..
Abstract: This paper discusses coordinated reactive power -
voltage (Q-V) control in a multi machine steam power plant. The
drawbacks of manual Q-V control are briefly listed, and the design
requirements for coordinated Q-V controller are specified.
Theoretical background and mathematical model of the new
controller are presented next followed by validation of developed
Matlab/Simulink model through comparison with recorded
responses in real steam power plant and description of practical
realisation of the controller. Finally, the performance of
commissioned controller is illustrated on several examples of
coordinated Q-V control in real steam power plant and compared
with manual control.
Abstract: Custom power is a technology driven product and
service solution which embraces a family devices such as Dynamic
Voltage Restorer (DVR), Distributed Shunt Compensator
(DSTATCOM), Solid State Breaker (SSB) etc which will provide
power quality functions at distribution voltages. The rapid response
of these devices enables them to operate in real time, providing
continuous and dynamic control of the supply including voltage and
reactive power regulation, harmonic reduction and elimination of
voltage dips. This paper presents the benefits of multilevel inverters
when they are used for DPC based custom power devices. Power
flow control mechanism, salient features, advantages and
disadvantages of direct power control (DPC) using lookup table,
SVM, predictive voltage vector and hybrid DPC strategies are
discussed in this paper. Simulation results of three level inverter
based STATCOM, harmonic analysis of multi level inverters are
presented at the end.
Abstract: The Inter feeder Power Flow Regulator (IFPFR)
proposed in this paper consists of several voltage source inverters
with common dc bus; each inverter is connected in series with one of
different independent distribution feeders in the power system. This
paper is concerned with how to transfer power between the feeders for
load sharing purpose. The power controller of each inverter injects
the power (for sending feeder) or absorbs the power (for receiving
feeder) via injecting suitable voltage; this voltage injection is
simulated by voltage drop across series virtual impedance, the
impedance value is selected to achieve the concept of power exchange
between the feeders without perturbing the load voltage magnitude of
each feeder. In this paper a new control scheme for load sharing using
IFPFR is proposed.