An Adaptive Soft Handover Scheme Using Fuzzy Load Balancing for WCDMA Systems

In cellular systems, user distribution variations can cause load imbalance between cells. Embedding a load balancing strategy within the handover scheme means that ensuing traffic congestion can be alleviated by dynamically reallocating load between neighbouring cells. An adaptive soft handover scheme for multimedia cellular communication systems is proposed in this paper, that considers both the cell load factors as well as the pilot channel signal-to-interference-and-noise-ratio (SINR) for soft handovers. By using fuzzy principles, the soft handover thresholds and time hysteresis are adapted dependent upon the loads of the neighbouring cells. Simulation results show that the new algorithm provides improved system performance in terms of a more evenly distributed load, lower blocking probabilities and higher throughput

Power system security enhancement by HVDC links using a closed-loop emergency control

In recent years, guaranteeing that large-scale interconnected systems operate safely, stably and economically has become a major and emergency issue. A number of high profile blackouts caused by cascading outages have focused attention on this issue. Embedded HVDC (High Voltage Direct Current) links within a larger AC power system are known to act as a “firewall” against cascading disturbances and therefore, can effectively contribute in preventing blackouts. A good example is the 2003 blackout in USA and Canada, where the Québec grid was not affected due to its HVDC interconnection. In the literature, many works have studied the impact of HVDC on the power system stability, but very few examples exist in the area of its impact on the system security. This paper presents a control strategy for HVDC systems to increase their contribution to system security. A real-time closed-loop control scheme is used to modulate the DC power of HVDC links to alleviate AC system overloads and improve system security. Simulations carried out on a simplified model of the Hydro-Québec network show that the proposed method works well and can greatly improve system security during emergency situations.Peer reviewedFinal Accepted Versio

Mengenal pasti tahap motivasi dan kecenderungan keusahawanan di kalangan pelajar semester akhir Ijazah Sarjana Muda Kejuruteraan Mekanikal : satu tinjauan di KUiTTHO

Keusahawanan merupakan bidang yang mencabar dan tidak ramai yang mahu menceburi bidang ini tenitaraa lulusan bidang kejnriiteraan. Mereka ini mempunyai elemen keusahawanan nntuk menjadi usahawan yang beijaya. Oleh itu, timbul persoalan mengapakah pelajar-pelajar ini kurang berminat dengan bidang keusahawanan?. Bersesuaian dengan pennasalahan tersebut, kajian ini dijalankan bertujuan untnk meninjau tahap motivasi bagi memberikan pendedalian dan menarik kecenderungan pelajar kejuruteraan terliadap bidang keusahawanan. Objektif kajian ini berdasarkan kepada beberapa aspek iaitn taliap pengetahuan keusahawanan, motivasi, kecenderungan terhadap bidang keusahawanan dan keperluan subjek atau elemen keusahawanan dalam jumsan kejuruteraan. Kajian yang telah dijalankan adalah kajian deskriptif berbentuk tinjauan yang menggunakan soal selidik sebagai instrumen untuk mendapatkan data. Dengan menggimakan persampelan rawak mudah, seramai 99 orang pelajar semester akhir ijazah Saijana Muda Kejuruteraan Mekanikal telah dipilih sebagai responden kajian. Instrumen kajian adalah soal selidik dan data-data yang diperolehi telah dianalisis menggimakan perisian Statistical Package For Social Science versi 11.0 untuk mendapatkan nilai min dan peratus. Hasil kajian mendapati bahawa pelajar-pelajai' ini mempunyai kecenderungan terhadap bidang keusahawanan dengan skor min keseluruhan 3.573 dan taliap motivasi keusahawanan yang tinggi dengan skor min keseluaihan 3.965 tetapi kekurangan pengetahuan dalam bidang keusahawanan dengan skor min 3.16. Oleh itu. adalah perlu elemen-elemen keusahawanan diterapkan ke dalam kuriknlum kursus kejuaiteraan

Application of AHP algorithm on power distribution of load shedding in island microgrid

This paper proposes a method of load shedding in a microgrid system operated in an Island Mode, which is disconnected with the main power grid and balanced loss of the electrical power. This proposed method calculates the minimum value of the shed power with reference to renewable energy sources such as wind power generator, solar energy and the ability to control the frequency of the generator to restore the frequency to the allowable range and reduce the amount of load that needs to be shed. Computing the load importance factor (LIF) using AHP algorithm supports to determine the order of which load to be shed. The damaged outcome of load shedding, thus, will be noticeably reduced. The experimental results of this proposed method is demonstrated by simulating on IEEE 16-Bus microgrid system with six power sources

DC microgrid power coordination based on fuzzy logic control

The power coordination in DC microgrids has a vital role in enhancing the performance and management of multi generation units. Renewable Energy Sources (RES) are limited to their available power with intermittent nature. Battery-based energy storage sources have limitations in the charging and discharging capabilities to avoid depleting the battery and preserve the State of Charge (SOC) within its satisfactory limits. The battery balances the power difference between RES and loads. However, in severe cases where the SOC is very low, load shedding is crucial. In this paper, a Fuzzy Logic Controller (FLC) has been proposed to coordinate the power flow of PV unit and battery to satisfy the load by full use of the available PV power. It controls the PV’s output power and keeps the SOC and charging / discharging power of the battery within their required margins regardless of the variations in load. Furthermore, load shedding of low priority load has been implemented when the battery couldn’t balance the microgrid power flow. Simplicity in managing multi input-multi output system by FLC is the main merit. Matlab/Simulink results are presented to validate the performance of the proposed controller

Evaluación de la seguridad dinámica en línea de una micro-red usando lógica difusa y procesamiento distribuido

La evaluación de la seguridad dinámica en línea se define como la habilidad de un sistema de potencia a soportar contingencias repentinas y sobrevivir el transitorio y llegar a un nuevo estado estacionario aceptable. Durante la operación del sistema la evaluación del nivel de seguridad dinámica es esencial para tomar medidas de control preventivas con el objetivo de llevar al sistema, en caso de que sea necesario, a un estado de operación más seguro. Debido a la gran complejidad de los sistemas de potencia y al gran número de componentes, la evaluación de la seguridad es computacionalmente compleja lo que la hace poco útil. Esto es más complejo cuando se desea evaluar la seguridad dinámica considerando las nuevas micro redes. Para afrontar este problema, se presenta un nuevo enfoque de evaluación de la seguridad dinámica en línea de micro redes. La propuesta emplea procesamiento distribuido y técnicas de inteligencia artificial para reducir los tiempos de cálculo lo que permite su ejecución en línea con la operación del sistema.Dynamic security assessment (DSA) is defined as the ability of a power system to withstand sudden contingencies and to survive the transient and to reach an acceptable steady-state condition. During system operation, the on-line assessment of the dynamic security level is essential in order to take adequate countermeasures aimed to restore the system, if necessary, to a more secure operating condition. Due to both the great complexity of latest power systems and the large number of components, the on-line DSA leads to excessive computational complexity which makes it not fully operational, particularly with the inclusion of complex emerging grid-tied AC micro grids. To overcome this problem, a new approach of on-line DSA of micro grids is presented in this paper. The proposal employs distributed processing and artificial intelligence (AI) techniques in order to reduce the computing times; thus allowing its execution on-line.Fil: Schweickardt, Gustavo Alejandro. Universidad Tecnologica Nacional. Facultad Regional Concepcion del Uruguay; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gimenez Alvarez, Juan Manuel. Universidad Nacional de San Juan. Facultad de Ingenieria. Departamento de Ingenieria Electromecanica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Prediction of classroom reverberation time using neural network

In this paper, an alternative method for predicting the reverberation time (RT) using neural network (NN) for classroom was designed and explored. Classroom models were created using Google SketchUp software. The NN applied training dataset from the classroom models with RT values that were computed from ODEON 12.10 software. The NN was conducted separately for 500Hz, 1000Hz, and 2000Hz as absorption coefficient that is one of the prominent input variable is frequency dependent. Mean squared error (MSE) and regression (R) values were obtained to examine the NN efficiency. Overall, the NN shows a good result with MSE 0.9. The NN also managed to achieve a percentage of accuracy of 92.53% for 500Hz, 93.66% for 1000Hz, and 93.18% for 2000Hz and thus displays a good and efficient performance. Nevertheless, the optimum RT value is range between 0.75 – 0.9 seconds

Ranking load in microgrid based on fuzzy analytic hierarchy process and technique for order of preference by similarity to ideal solution algorithm for load shedding problem

This paper proposes a method to rank the loads in the microgrid by means of a weight that combines the criteria together in terms of both technical and economic aspects. The fuzzy analytic hierarchy process technique for order of preference by similarity to ideal solution (fuzzy AHP TOPSIS) algorithm is used to calculate this combined weight. The criteria to be considered are load importance factor (LIF), voltage electrical distance (VED) and voltage sensitivity index (VSI). The fuzzy algorithm helps to fuzzy the judgment matrix of the analytic hierarchy process (AHP) method, making it easier to compare objects with each other and remove the uncertainty of the AHP method. The technique for order of preference by similarity to ideal solution (TOPSIS) algorithm is used to normalize the decision matrix, determine the positive and negative ideal solutions to calculate the index of proximity to the ideal solution, and finally rank all the alternatives. The combination of fuzzy AHP and TOPSIS algorithms is the optimal combination for decision making and ranking problems in a multi-criteria environment. The 19-bus microgrid system is applied to calculate and demonstrate the effectiveness of the proposed method