Imad Mougharbel

A review of matrix converters applied to PMSG based wind energy conversion systems

This paper presents a review of the recent advances in matrix converter topologies used with the permanent magnet synchronous generator (PMSG) in wind power generation systems. Dedicated literatures introduce different topologies inspired by the conventional matrix converter. Two-stage matrix converters known as sparse matrix converters are compared to the conventional matrix converter in terms of implementation complexity, cost, power rating and voltage ratio. Single-phase matrix converters topologies are implemented in high power wind applications in two different modular concepts: the reduced matrix concept for offshore wind farms and the multi-modular high power matrix converter. On the other hand, several modulation techniques applied to the matrix converter-PMSG scheme are briefly presented.

Simulation of a hybrid renewable energy system in rural regions

This paper presents the design of a MATLAB simulator of a hybrid renewable energy system applied for energy generation in rural regions. The system is simulated using MATLAB. It consists of a set of photovoltaic panels, a DFIG wind farm, a pumped water storage/generation station and it is designated to supply residential/industrial loads. A transmission line connects this system to the main power grid. Although conventional models are used, the work originality consists of performing an optimal control of sources and loads in order to keep power balancing between generation and consumption in both connected and islanded modes.

A new adapted back-off scheme for broadcasting on IEEE 1609.4 control channel in VANET

In this paper, we propose a novel MAC scheme for broadcasting in IEEE 802.11p/WAVE standard during the CCH periods. We address two problems which lead to the same undesired result: the degradation in control channel performance. The first problem is related to the congestion control and the challenge is viewed in the random backoff mechanism to be adapted for broadcasting messages. It has been evident that the exponential back-off is not efficient in broadcast and where there are beacons. The problem becomes more challenging when these beacons have an expiry time and they are dropped once this time is reached before transmission. When the vehicle density is high, the probability to have two or more vehicles having the same random back-off increases and results in an increase of collision probability. One solution is in incrementing the Contention Window (CW) but if the CW is increased, the waiting time before transmitting increases and it results in the rise of the packet drop rate due to expiry time. The absence of acknowledgement for broadcast messages makes the CW adaptation very difficult. Our proposed scheme addresses this problem. This paper also covers the issue of channel congestion phenomenon following a channel switch (from SCH to CCH) mentioned in Annex B of the IEEE Std 1609.4-2010. Just after a channel switch, a large number of WAVE devices are found in a period of above-average channel congestion resulting in an unexpectedly high collision rate. Our scheme presents a MAC layer approach used by the devices to avoid the “start-of-interval contention”, especially in a high vehicle density. Our simulation results show that using a modified backoff procedure after spreading the density of transmissions on the CCH interval is an effective solution to decrease the collision probability and increases the packet reception rate. The spread is based on geographical positions. Moreover, the modified backoff, instead of freezing the counter when the channel is occupied, it still decreases it.

A review of modulation and control strategies for matrix converters applied to PMSG based wind energy conversion systems

This paper presents a review of modulation and control strategies for matrix converters applied to permanent magnet synchronous generator (PMSG) in wind power generation systems. Modulation techniques already discussed in scientific literature for the command of matrix converters are mostly divided into three categories: the scalar modulations, the pulse width modulations and the predictive control modulations. These modulation methods are combined with maximum power point tracking (MPPT)-based control strategies to secure and improve the performance of the overall system. Control strategies are combinations of two elementary blocs: the MPPT algorithms and the regulation approach. MPPT algorithms are crucial for the improvement of wind harvest and regulation approaches are generally based on adaptive, non-linear or linear automatic methods that are responsible for current control or field oriented control or reactive power control.

Considerations for implementing a wireless network for landmine detection

This work concerns a new approach for detecting landmines based on a wireless sensor network (WSN). The architecture of the WSN is described and a networking configuration is given. Each node of the network is represented by interconnected integrated modules. The design of these modules is based on the integration facility and on its operation in a mine field environment. The node design should be optimized by reducing dimensions and minimizing energy consumption. This paper presents most important considerations for the node design. It shows that the biosensor is the most suitable detection technology for this approach. It also describes an algorithm that could be used for landmine positioning. The algorithm is based on measuring the concentration of explosive particles transmitted in the air. Finally, this paper suggests solutions to be validated in the future for improving accuracy and performance.

Comparative control analysis of the Vienna rectifier based on its averaged model

This paper presents a comparative evaluation of two multiple-loops duty-cycle-based control schemes applied to a three-phase three-switch three-level boost-type rectifier. The control laws are both elaborated on the basis of a state-space averaged model of the converter, expressed in the synchronous rotating frame. On the one hand, a control scheme that uses linear regulators is designed by using the small-signal transfer functions of the converter’s model, which was linearised on the neighbourhood of a suitable steady-state operating point. On the other hand, a non-linear control scheme that uses the input-output feedback linearisation approach is also designed in order to satisfy the same requirements as for the linear control system. For comparison purpose, both control schemes are implemented numerically using the Simulink tool of Matlab, and simulation experiments are carried out in order to test and verify the tracking and regulation performance of each control law, as well as their robustness towards load or mains source disturbance. For the same operating conditions, the performance of the two control laws are analysed and compared in terms of line currents total harmonic distortion (THD) and DC voltage regulation.

Hybrid multi-channel multi-hop MAC in VANETs

In this paper, we propose a Hybrid Multi-Channel Multi-hop Medium Access Control (HMM-MAC) meeting the safety and non-safety requirements in Vehicular Ad-hoc Networks when no infrastructure is present (V2V communication) with only a single transceiver at each vehicle. The simulation results showed that our scheme could achieve a higher delivery ratio of road safety messages and a high probability to select a free transmission channel in a certain region and during a certain time.

An efficient implementation of the Self-Organizing Map algorithm for power network partitioning

This paper describes a Self-Organizing Map (SOM) algorithm and its use for electric network partitioning. A comparative study has shown in a previous work that the SOM algorithm gives the closest result to the ideal case. In this paper, this algorithm is improved due to the consideration of two inputs instead of one. Voltage and phase angle variations are applied as inputs. The proposed idea is tested on an IEEE 39-bus system and an IEEE 118-bus system. Simulation results show that this approach gives more coherent and tightened partitions.

Pilot buses selection used in secondary voltage control

Penetration of electrical sources based on renewable energies is becoming more and more significant in power transportation and distribution. Changes caused by this integration have an important impact on the network stability. This instability is avoided through the three hierarchical voltage control levels. In this paper we focus on the selection of pilot buses for the secondary level voltage control. Pilot buses are those where regulators are installed and the objective is to find the most appropriate selection that minimizes their number and maximizes the stability performance. A comparison between all existing selection algorithms is performed then an improvement is made on the most performing one. Results are validated by doing simulations on the standard IEEE 118 bus.

Comparative study of the optimization theory for cancer treatment

In order to assure hygiene safety for patients, optimal use of drugs is necessary for controlling the number of clinically observed tumor cells. Based on a mathematical model of drug therapy for cancer, and on an objective function, the optimal solution is reached. The model therapy is considered for an individual patient over a fixed time horizon. The disease dynamics are given by an ordinary differential equation that describes the evolution of cancer cells in time. An optimization theory is applied in order to minimize the number of cancer cells at the end of treatment. A comparative study is performed on different treatments profiles applied to different types of cancer. This study shows the usefulness of the suggested mathematical deterministic or hybrid model. It considers the treatment in terms of duration and drug dosage, the initial number of detected cancer cells and the objective function.