Muhd Hafizi Idris

Effective two-terminal single line to ground fault location algorithm

This paper presents an effective algorithm to locate Single Line to Ground (SLG) fault at a transmission line. Post fault voltages and currents from both substation terminals were used as the input parameters to the algorithm. Discrete Fourier Transform (DFT) was used to extract the magnitudes and phase angles of three phase voltages and currents. The modeling of the transmission line along with the algorithm was performed using Matlab/Simulink package. The results of fault location for SLG faults along the transmission line demonstrated the validity of the algorithm used even for high resistance earth fault.

Adaptive Mho type distance relaying scheme with fault resistance compensation

This paper describes an adaptive distance relaying scheme which can eliminate the effect of fault resistance on distance relay zone reach. Distance relay is commonly used as main protection to protect transmission line from any type of fault. For a stand-alone distance relay, fault resistance can make Mho type distance relay to be under reached and thus the fault will be isolated at a longer time. In this scheme, the relay detects the fault location using a two-terminal algorithm. By knowing fault location, fault voltage at the fault point can be calculated by using equivalent sequence network connection as seen from local terminal. Then, fault resistance is calculated by using simple equation considering contribution from remote terminal current. Finally, the compensation of fault resistance is done onto calculated apparent resistance as seen at relaying point. The modeling and simulation was carried out using Matlab/Simulink software. Several cases were carried out and the results show the validity of the scheme.

Analysis the Condition of RazakSAT Based on Attitude Sensor of Atttitude Determination System Data

Attitude determination system (ADS) is a process to control the orientation of the satellite to make sure that the orientation is relative to inertial references frame such as Earth. ADS is consists of mathematical algorithm and sensor as a references measurement to determine attitude of satellite. Since RazakSAT in the orbit, the sensor such as sun sensor, magnetometer and gyroscopes are used to control angular rotation and prevent high spin rates that can damage the satellite. This paper presents the analysis on sensor of attitude determination system based on RazakSAT data. Matlab was used to analyze the X,Y and Z axis of the sensor to determine the condition of the satellite.

Modeling and simulation of inverse time overcurrent relay using Matlab/Simulink

Overcurrent relay is an important relay used to protect transmission and distribution feeders, transformer, bus coupler etc. It can be used as main or backup protection relays. The modeling of overcurrent relay and other protection relays is important in the research on the effects of network parameters and configurations on the operation of these relays. This research deal with modeling and simulation of inverse time overcurrent relay using commonly used Matlab/Simulink software. The developed model was tested with single line to ground fault and phase to phase fault with various fault locations and fault resistances to evaluate phase and earth detectors in sensing the fault current. Simulations results show the feasibility of the software to be used to develop the relay.

Reviews on MATLAB DSTATCOM Simulation Models in Mitigating Power Quality Problems

This paper reviews the performance of detailed and average model for distribution static compensator (DSTATCOM) in order to remove voltage flicker, regulate the voltage at point of common coupling (PCC), power factor correction and harmonics elimination. In these models, d-q theory is used to extract fundamental active and reactive power components of the load currents which will be required to estimate the reference source currents. Both models are evaluated and compared in MATLAB/Simulink based simulation platform.

The Effect of Harmonic Distortion on the Performance of Differential Relay for Distribution Transformer Protection

This paper aims to analyzing and probing the influences of power system harmonics on a differential relay used for distribution transformer protection. The increased use of nonlinear devices in industry, commercial and residential areas can lead to a significant increase the level of harmonic distortion in the power system. This harmonic has the significant effects to the differential protection systems components such as current transformer (CT) and relay. The CT tends to saturate due to the presence of current harmonics in power system, so it will produce magnitude secondary current error and make the differential relay to miss operations. The harmonic distortion effects on the differential protection have been investigated through laboratory test. To determine the CT errors when operates under harmonic condition, the CT has been test with certain level of THDi. The result of this testing was found that with increasing of the THDi, the magnitude of secondary current error increased and differential relay will operate at no fault conditions.

Performance of Distributed Generation (DG) towards Dynamic Voltage Restorer (DVR) in Mitigating Voltage Dips

This article presents the performance of Distributed Generation (DG) towards Dynamic Voltage Restorer (DVR) in mitigating voltage dips. An investigation was conducted to explore the effect of DG with the test system and the results will be analyzed during line to ground fault with DVR contains DG and without DG. The percentages of the voltage dips that occur will be compared between all the test systems. From this analysis of voltage dips percentage, the effectiveness of the DG towards DVR in mitigating voltage dips can be obtained clearly. The simulation of the test system will be done using Power System Computer Aided Design (PSCAD) software.

Accurate phase to phase fault resistance calculation using two terminal data

Faults can occurred at the transmission line due to lightning strike, broken conductor, cross arm or tower falls, danger tree, crane or animal encroachment, polluted insulator etc. Each type of fault will represents a fault resistance value. Fault resistance will affects the accuracy of protection relays in fault location and fault zone detection. Phase to phase fault is one type of unsymmetrical fault at the transmission line. This paper represents the accurate way to calculate the actual phase to phase fault resistance value by using data from both local and remote substations. From the finding, the actual fault resistance can be represented by fault resistance as seen from local substation in parallel with the fault resistance as seen from remote substation. To prove the finding, simulation has been carried out and the results show the validity of the proposed theory.

Adjustable Speed Drives Response to Voltage Sags

This paper presents a study to investigate response of adjustable speed drives due to voltage sags. A small ASD of 0.39 kW, 50/60 Hz, and 400-480 V was used for testing how drives will respond to voltage sag types; A, B, C and D. The drive response is influenced by sag magnitude, sag duration and phase angle shift. Behavior of the diodes rectifier for conducting is influenced by sag magnitude and phase angle shift represented by sag of types C and D. The diodes rectifiers are reverse biased when it was supplied by voltage sags. Even though there are no charging currents to dc bus capacitor during voltage sags, the drives did not directly trip to certain sag magnitude and sag duration. Sensitivity of the ASD to voltage sag types is presented in voltage tolerance curve. Sag of type A produces highest sensitivity on the ASD and it trips for sag magnitude of 62.5% and 250 milliseconds in duration.