Zuhairi Baharudin

Electricity forecasting for small scale power system using fuzzy logic

Electricity supply to Universiti Teknologi PETRONAS (UTP) comes from gas district cooling (GDC) plant as a primary source of energy and utility company Tenaga Nasional Berhad (TNB) as a backup. With a maximum capacity of 8.4 MW which comes from 2 nos of gas turbine generators rated at 4.2 MW each, this work aims to forecast short term electricity demand of the plant. As a sole customer of the plant, UTP 2008 electricity demand data is being used as a basis to design a forecast model using Fuzzy Logic. With the forecast model, it will help GDC for pre-planned scheduling and maintenance of the plant and also as guidance for the daily operation of the plant. The proposed fuzzy logic model is applied to obtain one week forecast load demand data for GDC. The forecast accuracy is obtained and it is represented in mean absolute percentage error (MAPE).

Electricity forecasting for small scale power system using artificial neural network

Short term load forecasting (STLF) method is the basis of efficient operation for power system. It has an important role in planning and operation of power system. In this paper, a practical STLF using artificial neural network method (ANN) for Gas District Cooling (GDC) power plant of Universiti Teknologi PETRONAS (UTP) is presented. As a sole customer of GDC power plant, the load data from 2006 till 2009 are gathered and utilized for model developments. The developed models forecast electricity load for one week ahead. The paper proposes a method of a multilayer perceptron neural network and it is trained and simulated by using MATLAB. The models have been tested with the actual load data and perform relatively good results.

Investigation on high neutral earthing resistor temperature when islanded generator connected to utility grid

Electricity supply to Universiti Teknologi PETRONAS (UTP) is provided by two generating units at gas district cooling (GDC) plant located in the campus. Under normal operation, UTP power system is operating in island mode and during emergency, it will be connected to utility grid of Tenaga Nasional Berhad (TNB). Each generating unit is grounded through neutral earthing resistor (NER). It has been observed that NER temperature become high when generator operating in parallel with the grid. Investigation reveals that triplen harmonics currents continuously flow through NER during island and parallel operation. Higher triplen harmonics currents are noticed during parallel operation as compared to island mode of operation. High NER temperature is caused by increase in triplen harmonics currents that flow through it. The above phenomena are described in this paper together with some proposed measures to overcome the problem.

Aperture and Mutual Coupled Cylindrical Dielectric Resonator Antenna Array

A 1 £ 3 element linear array using cylindrical dielectric resonator antennas (CDRAs) is designed and presented for 802.11a WLAN system applications. The top and bottom elements of CDRA array are excited through the rectangular coupling slots etched on the ground plane, while the slots themselves are excited through the microstrip transmission line. The third element (i.e., central CDRA) is excited through the mutual coupling of two radiating elements by its sides. This mechanism enhances the bandwidth (96.1%) and gain (14.3%) as compared to aperture coupled technique. It is also observed that the side lobe levels are reduced over the designed frequency band. Using CST microwave studio, directivity of 10.5dBi has been achieved for operating frequency of 5.6GHz. Designed antenna array is fabricated and tested. Simulated and measured results are in good agreement. The equivalent lumped element circuit is also designed and presented using Advanced design system (ADS) for this proposed array.

Triplen harmonics currents propagation through medium voltage distribution network

Harmonics propagation can be studied by various harmonics load flow methods. The propagation of balanced triplen harmonics currents produced by synchronous generator through medium voltage underground cable of distribution network can be modeled by triplen harmonics voltages acting as the source for zero sequence network. Third harmonics current being a major component of triplen harmonics is being studied for various underground cable parameters, generator and transformer grounding methods, load variation/connection and distributed generation configuration. Time domain analysis is used for simulation and the model is validated with the third harmonics current measurement at site. Third harmonics current propagation is influenced by third harmonics voltage source, cable length, generator grounding, number of parallel cables, cable size, load, load connection and DG configuration.

A Comparative Analysis of Neural Network Based Short Term Load Forecast Models for Anomalous Days Load Prediction

Load forecasting plays a very vital role for efficient and reliable operation of the power system. Often uncertainties significantly decrease the prediction accuracy of load forecasting which affect the operational cost dramatically. In this paper, comparison of Back Propagation (BP) and Levenberg Marquardt (LM) neural network (NN) forecast model for 24 hours ahead is presented. The impact of lagged load data, calendar events and weather variables on load demand are analyzed in order to select the best forecast model inputs. The mean absolute percentage errors (MAPE), Daily peak error and regression analysis of NN training are used to measure the NN performance. The Forecast results demonstrate that, LM based forecast model outperform than BP NN model for performance matrices. This model is used to predict the load of ISO-New England grid. Index Terms—Short Term Load Forecasting (STLF), Neural Network (NN), Back Propagation (BP), Levenberg- Marquardt (LM), Mean Absolute Percentage Error (MAPE), Regression Analysis (RA).

Development of chaotically improved meta-heuristics and modified BP neural network-based model for electrical energy demand prediction in smart grid

In this paper, a modified backpropagation neural network is combined with a chaos-search genetic algorithm and simulated annealing algorithm for very short term electrical energy demand prediction in deregulated power industry. Multiple modifications are carried out on the conventional backpropagation algorithm such as improvements in the momentum factor and adaptive learning rate. In the hybrid scheme, the initial parameters of the modified neural network are optimized by using the global search ability of genetic algorithm, improved by cat chaotic mapping to enrich its optimization capability. The solution set provided by the optimized genetic algorithm is further improved by using the strong local search ability of simulated annealing algorithm. The real data of New South Wales, Australian grid, is used in the experimentation for 1-h-ahead forecast with an emphasis on data analysis and preprocessing framework. The correlation analysis is used for the identification and selection of the most influential input variables. The simulation results reveal that the proposed combination technique effectively enhanced the prediction accuracy as compared to the available conventional methods. The prediction of 1-h-ahead load demand is critically important for decision-making response of the modern smart grid system. The acceptable precision of the proposed model concludes that it can be applied in the smart grid to enhance its demand responsiveness and other intelligent features.

RF MEMS Based Half Mode Bowtie Shaped Substrate Integrated Waveguide Tunable Bandpass Filter

A tunable planar bandpass filter based on a technique that utilizes a half mode substrate integrated waveguide (HMSIW) and novel inter-resonator coupling is presented. The tunable HMSIW based bandpass filter is implemented using two half triangle shaped cavities coupled together through inter-resonator coupling forming half mode bowtie shaped structure. The bowtie-shaped filter exhibits similar performance as found in rectangle- and circle-shaped SIW based bandpass filters. This concept reduces the circuit foot print, and miniaturization high quality factor is maintained by the structure. The tunable filter utilizes packaged RF MEMS switches; switching between different configurations of switches achieves four distinctive frequency states between 4.8-5.3 GHz. The filter maintains a constant absolute 1 dB bandwidth of 100 ± 10 MHz for all frequency states.

PC Based Energy Efficient Wireless Transceiver Module with ZigBee

The aim of this research is to develop a low power, low cost and energy efficient transceiver model which is integrated with programmable microcontroller and ZigBee transponder. A combination of programmable microcontroller with ZigBee transponder is used to control the transceiver module with computer commands. It has b een simulated for transmitting and receiving the communication signals from any movable device with more efficiently and use low power consumption. ZigBee Transponder is preferable as compared to radio frequency identification (RFID) due to IEEE 802.15.4 standard that promises stable data transmission with low power consumption device and having higher network flexibility. PIC 16F877A programmable microcontroller with coding in Mikro C software is simulated and used with computer control instructions. Series of experiments has been conducted to ensure the stability and low power consumption of this model.

The study of triplen harmonics currents produced by salient pole synchronous generator

Triplen harmonics study for harmonics produced by salient pole synchronous generator is very important because their presence have caused communication line interference, damage to neutral earthing resistor etc. The purpose of this paper is to study the characteristics of triplen harmonics under balanced/unbalanced resistive/inductive loads, different generator neutral earthing resistor values and various transformer winding configurations. Lab scale salient pole synchronous generator is used for the experiment and third harmonic currents are recorded for analysis to represent triplen harmonics currents characteristics. Under balanced load, third harmonic current is inversely proportional to load impedance and neutral current is three times the phase current. During unbalanced load condition, the neutral current is lower than arithmetic sum of phase current due to different phase current magnitude and angle. The phase and neutral third harmonic currents magnitude is inversely proportional to generator NER resistance under balanced load. Transformer winding configurations under balanced load permit third harmonic current flowing through them in accordance to zero sequence network for the transformer apart from higher transformer reactive impedance at third harmonic. This study provides a very important input to mitigation method in reducing triplen harmonics currents propagation in the network.