K. M. Nor

Analysis of distribution transformer losses and life expectancy using measured harmonic data

Three-phase distribution transformer in electrical power systems are usually designed for utilizing at the rated frequency and linear load. A different performance compared with that of the designed transformer occur when non-linear loads introduce harmonics to the supply. With the increasing use of nonlinear load the harmonic ay overheat the transformer leading to a poor power quality. The increased losses in the transformer due to the harmonic distortion can cause unnecessary winding loss and typical temperature rise. This paper presents the analysis and evaluation of distribution transformer losses under non-linear load by using real data. In this study, losses caused by harmonic and life of the distribution transformer were determined. Results show that an increase in the current harmonic distortion will increased in the current harmonic distortion will increase the transformer losses and hence decreased its life expectancy.

Modeling and simulation of grid connected Photovoltaic System for Malaysian climate using Matlab/Simulink

The impact of solar irradiance, ambient temperature and clearness index on the outdoor performance of poly-crystalline (poly-Si) PV modules is considered. This paper highlights the effect on the energy output by changing the clearness index for the Building Integrated Photovoltaic System (BIPV) in Malaysia. Simulation was implemented using MATLAB/SIMULINK and results are compared with the actual monitored data. A case study was presented for a 45.36 kWh system using poly-crystalline module and results show that the energy output differs from 7.23% to 8.52% with clearness index of 0.55 and hence clearness index also influenced the energy output besides solar irradiance and temperature.

Experimental study on the impact of harmonics on transformer

Impacts of harmonics on step-down transformer are presented in this paper. Transformer failure had been reported due to harmonic current causing excessive winding temperature rise. Excessive temperature rise of transformer is due to harmonic effect result in higher power loss than normal operating mode. An experimental setup is proposed which allow for observation of harmonics. This research focuses on the transformer losses under nonlinear load with different power consumption. Moreover, the trends of Total Harmonic Distortion (THD) with nonlinear load are reported.

Impact study of practical harmonic data using time series simulation

With the increasing proliferation of non-linear loads, more harmonics are expected to be injected into the distribution system. This paper presents time series simulations of harmonic analysis in the distribution system. Modeling and analysis approach is used to perform the time series of harmonic analysis. OpenDSS, an open-source distribution system simulator is utilized in order to perform the studies needed. This paper also includes several case studies based on IEEE test feeder and are analysed by utilizing the harmonic power flow analysis. The time-series simulation is performed by using the practical harmonic data obtained from the industries.

Voltage stability assessment: An approach with expanded Newton Raphson -Sydel

Voltage instability is major cause of cascading failures in the current power systems. Static assessment of voltage stability has been used widely to draw the secure margin of voltage security for the system components. Among the many methods reported, Conventional Newton Raphson method is popular but it suffers from curse of singularity on its Jacobian matrix which precludes converging onto the solution. To overcome this problem, Continuation Power Flow (CPF) method was come up. CPF method is a very powerful method that can give the solution without having the singularity problem. The CPF method has then been improved using new CPF-GMRES method. In contrary, NRS (Newton - Raphson - Seydel) is old method but is fast and accurate. This paper expands existing NRS method which then demonstrated that it is more reliable and faster than CPF-GMRES and NRS. The algorithm tested on practical 350 bus network in IRAN (Khorasan region).

Experience in online power quality monitoring through VPN

The concern towards power quality has increased rapidly due to the amount of losses it created. Throughout the world, many researchers have proposed a study on various aspects of power quality, which may be used to overcome or reduce the effects. In this paper, a project initiated by the Energy Commission of Malaysia has been carried out to find the level of power quality in Malaysia as well as to estimate the cost associated with power quality. The Malaysian data on power quality will be recorded and collected online by using the standards compliance equipments, Fluke 1750. The advanced in the communication network has made this project successful as a large amount of data can be downloaded online. The analysis of the recorded data can be made systematically as much software is available in the market which helps the consultant to develop a more user friendly database. The findings from this project will be used to determine the best possible solution for the national interest.

Use case approach for developing object oriented power system studies: object oriented three phase load flow

The paper presents the application of the use case approach for developing reusable power system components. Object oriented three phase load flow is introduced as an example. The three phase load flow development is based on the symmetrical components theory and the decoupled models of the untransposed transmission lines. The well known Newton Raphson and Fast Decoupled algorithms are chosen in the development. The three phase load flow is solved by incorporating the solution of the positive sequence load jlow and the negative sequence and zero sequence nodal voltage equations. The different use cases are studied before the code implementation. Based on these use cases, an analysis model is constructed The clear advantage of the use case approach is that it defines the reusable objects before the code implementation.

Voltage sags cost estimation for malaysian industries

In this paper, a project initiated by the Energy Commission of Malaysia has been carried out to find the level of power quality in Malaysia as well as to estimate the cost associated with power quality. Normally, industry has a production target to be achieved yearly. To maintain the quality of production, several factors must be taken into account, such as labor quality, working environment and facilities. However, the quality of power supply is the most significant factor to ensure the continuous production. Nowadays, the power quality problems are increasing dramatically with the increasing use of non-linear load. Studies from other countries have shown that this problem can cause substantial issues. The impact of power quality problems, especially voltage sag on several industries in Malaysia and the costs incurred are discussed in this paper. The estimation of cost is calculated for a voltage sag events that has been captured from the optimum monitor locations. The estimation is made based on the size of the affected area and the number of large power consumer in that affected area.

A simple modeling technique of harmonic analysis for transformer

This paper presents an experimental setup to measure and compute the parameters required to construct a system model in simulation. The overall system model consists of a transformer model used to connect between the power source and harmonic load current injection model. The characteristics of the distorted current were modeled with harmonic magnitude and phase angle. The system model was then tested to further analyze the effect of the variation parameter of winding transformer toward its efficiency. The system model provides an interface which allows analysis to be performed for low power consumption equipment in large scale application harmonic study.

A system-wide power quality monitoring using machine-to-machine wireless broadband technology

The concern towards power quality has increased rapidly due to the amount of losses it created. Throughout the world, many researchers have proposed a study on various aspects of power quality, which may be used to overcome or reduce the effects. In this paper, a project initiated by the Energy Commission of Malaysia has been carried out to find the level of power quality in Malaysia as well as to estimate the cost associated with power quality. The Malaysian data on power quality will be recorded and collected by using the standards compliance equipments, Fluke 1750. The advanced in the communication network has made this project successful as a large amount of data can be downloaded online. The analysis of the recorded data can be made systematically as much software is available in the market which helps the consultant to develop a more user friendly database. The findings from this project will be used to determine the best possible solution for the national interest.