Applied Mechanics and Materials Vol. 785

Abstract: Optimal Reactive Power Dispatch (ORPD) is needed for reduces the power system losses and improves voltage profile, power system security and overall power system operation. In this paper, the ORPD problem solved using Constrained Reactive Power Control (CRPC) based Multi-Objective Evolutionary Programming (MOEP) optimization technique considering multi-contingencies (N-m). The proposed technique determines the optimum reactive power to be dispatched by the generators in order to improve voltage stability condition of a system. A computer program was written in MATLAB and the proposed technique was tested on the IEEE 30-bus RTS. Hence, the result was compared with Multi-Objective Artificial Immune System (MOAIS) to highlight it merits.

Abstract: This paper presents a computationally accurate technique to design an automatic single phase power factor controller by using microcontroller. The hardware implementation was developed by using Arduino Uno Rev-3 main board which uses the ATmega328 as the microcontroller. The power factor value from the load was measured by using voltage and current transformers, zero crossing detectors, and ATmega328 microcontroller. Zero crossing detectors produced current and voltage signals which will be measured and calculated for the time difference between both signals by ATmega328 microcontroller using appropriate algorithms in order to obtain value of power factor. The ATmega328 is programmed to automatically switch on and off capacitor function in order to control the signal pulse send to relay to connect and disconnect capacitor parallel with the load when energized and de energized if the calculated power factor value is either below 0.9 or above 0.9, respectively. Simulation of the power factor controller model was performed by using Proteus software. Arduino IDE software was used as the compiler for the Arduino Uno. The main objective is to study and develop the technology of automatic single phase power factor controller using Arduino Uno Rev-3 by controlling the power factor of the inductive load near to unity power factor. The results of the power factor value were displayed on the LCD and the power factor is corrected if it falls below 0.9 in order to prevent penalty by the power supplier. The effectiveness of the proposed technique could assist the monitoring unit in order to maintain the power factor at the value set by the utility.

Abstract: Low frequency oscillation (LFO) is a serious threat to the interconnection of power system and its safe operation. In this paper, optimum damping performances over LFO is achieved by implementing Bijective Differential Search Algorithm (B-DSA) to large interconnected power system. Conventional two stages lead-lag compensator is optimized as the Power System Stabilizer (PSS) and Linear Time Invariant (LTI) State Space system models are used to conduct stability analysis of power system. The tuning problem of PSS in multimachine system was formulated as a multi-objectives function. The simulations are conducted in 5-AREA 16 Machine test power system for severe system fault in order to verify the robust design of damping controller. The obtained results are compared with standard DSA optimization technique. The findings show the improved damping achieved by B-DSA than DSA algorithm. The settling times achieved using B-DSA based designed PSSs are 3.74sec and 4.57sec for local mode and inter-area mode of oscillations respectively. The successful damping over oscillation modes of LFO justifies the proposed technique is efficient for the improvement of power system security in adverse condition.

Abstract: In power system, load variation can cause instability condition. Transformer Tap Changer (TTC) adjustment can be used to alleviate this condition. This paper proposes an algorithm to optimize the adjustment of TTC termed as Cascaded-Evolutionary Programming (EP). This is to allow fine-tuning process on the results if the optimized results are beyond the acceptable range. The Tests were conducted on IEEE 14-Bus Reliable Test System (RTS) to determine minimum Voltage Profile (VP),V_min at selected load bus, using ordinary Load Flow thus maintaining the voltage at 0.9 p.u. to 1.5 p.u. The result demonstrates the pre-optimization and post-optimization of the minimum VP, V_min in the system and proves that the proposed algorithm technique identifies the optimum value of TTC whilst reducing computational time.

Abstract: This paper presents prediction of total harmonic distortion (THD) on Grid Connected Photovoltaic (GCPV) power systems towards Malaysia climate variations (solar irradiance) by using Mathematical approach. The actual and prediction data measurement were analyzed on three types of solar cell technologies; monocrystalline, polycrystalline and thin film. Each PV array works with different types of inverters which are located at Green Energy Research Center (GERC), University of Technology MARA (UiTM) Shah Alam, Selangor. The prediction and detail analysis of total harmonic distortion is carried out by using MathCAD software. The results obtained show good agreement between prediction and actual data.

Abstract: This paper presents a computationally accurate technique used to determine the estimated average probability of a system cascading collapse in association with the effect of hidden failure on a protection system. This includes an accurate calculation of the probability of hidden failure as it will provide considerable effect on the results of the estimated average probability of system cascading collapse. The estimated average probability of a system cascading collapse is then used to determine the sensitive transmission contributing to a higher risk of a system cascading collapse. This information is important because it will assist the utility to determine the critical transmission lines before the occurrence of critical power system cascading collapse. Comparative study has been done with other techniques to verify the effectiveness of the proposed method used in the determination of sensitive transmission lines.

Abstract: Cascading outage is a sequence of multiple dependent component outages that gradually happened in a power system. One of the main reasons is due to the hidden failure in a protection system that may cause to a power system instability leading to a system cascading collapse. This paper presents a computationally realistic technique used to determine the estimated average probability of a dynamic system cascading collapse in conjunction with the effect of hidden failure on a protection system. This includes a realistic calculation of the probability of hidden failure as it will provide significant impact on the results of the estimated average probability of dynamic system cascading collapse. The estimated average probability of a system cascading collapse is then used to identify the severity of total loading condition leading to a higher risk of a dynamic system cascading collapse. This information is essential for the reason that it will assist the power system utility to determine the highest point of increased system loading condition before the occurrence of critical power system cascading collapse.

Abstract: A conventional electrical distribution system are not designs to deal with harmonics because at that time the linear load conquer the consumer demand. Over the years with growing use of nonlinear load such as personal computer can contribute to harmonics current occur on electrical distribution system. With the presence of harmonics current on electrical distribution system leads in degradation of system performance. Therefore necessary actions are needed in order to minimize harmonics effect. The predominant harmonics should be eliminated from electrical distribution system such as 5^th and 7^thof harmonics current component. The eliminating process is achieved by implementing the current phase shifting technique on new concept of modern electrical distribution system at Makmal Komputer 3, Faculty of Electrical Engineering, UiTM Pulau Pinang.

Abstract: The objective of this paper is to present the challenges, methodological approach and possible solutions for the overvoltage issue during the winter light load period in the Main Interconnected Transmission System (MITS) of Oman after introducing the new 400kV system. Load flow studies of the planned MITS in 2016, including representation of other local and GCC interconnection grids, have shown overvoltage issues at the 400kV substations in Oman during winter off-peak demand. These voltage issues can even lead to difficulties in synchronizing the 400kV circuits. Simulation results are presented to define the size and location of a reactive power compensator which can resolve such overvoltage issues. Many options of the reactive power compensation, including fixed and variable means, have been studied and the best option (fixed shunt reactors) is selected.

Abstract: This paper proposes a nonlinear analysis of voltage sag magnitude and angle for fault distance calculation in distribution system. The method first identifies the fault section. Then, a rank approach is followed to identify and prioritize the faulty section. Later, the fault distance is calculated by creating a second order polynomial passing through the fault node. The testing is carried out in an actual distribution system of an electrical utility in Malaysia with 37 nodes. The test results show that the proposed fault distance gives very small percentage error.