Dimas Anton Asfani

Temporary short circuit detection in induction motor winding using combination of wavelet transform and neural network

Monitoring system for induction motor is widely developed to detect the incipient fault. Such system is desirable to detect the fault at the running condition to avoid the motor stop running suddenly. In this paper, a new method for detection system is proposed that emphasizes the fault occurrences as temporary short circuit in induction motor winding. The investigation of fault detection is focused on the transient phenomena during starting and ending points of temporary short circuit. The proposed system utilizes the wavelet transform for processing the motor current signal. Energy level of high frequency signal from wavelet transform is used as the input variable of neural network which works as detection system. Three types of neural networks are developed and evaluated including feed forward neural network (FFNN), Elman neural network (ELMNN) and radial basis functions neural network (RBFNN). The results show that ELMNN is the most simply and accurate system that can recognize all of unseen data test. Laboratory based experimental setup is performed to provide real-time measurement data for this research.

Application of health index method for transformer condition assessment

Power transformer is one of the electrical equipment that has a central and critical role in the power system. In order to avoid power transformer failure, information system that provides the transformer condition is needed. This paper is present the information system for diagnostic transformer condition based on health index. Health Index method provides a comprehensive transformer condition assessment. This method is resulting power transformer condition that divided into several categories according to the life time prediction and degradation level of transformer components. Analysis on dissolved gas, oil, and furan (insulation paper) are subjected to detect the faults types that could be occurs in transformer. The outputs of the analysis are life time prediction, types of possible faults, and recommendations for future maintenance action. For practical application, this method is applied to the transformer data test that provided by Indonesia Power Electric Company or PT PLN. Results of the analysis found that the smaller Transformer Health Index means greater number of population failure probability. This relationship is quite strong with the value of the correlation coefficient r is -0.63.

Wavelet-LDA-neural network based short circuit occurrence detection in induction motor winding

The paper proposes the short circuit identification method for induction motor winding. Four states of motor operation are defined as normal operation, starting of short circuit, steady state short circuit and ending of short circuit. The neural network based detection system is utilized to distinguish these defined operation states. Motor current is processed using discrete wavelet transformation to extract energy component of high frequency signal, which is latterly used for variable detection. Three different wavelet types varied by five levels of transformation are evaluated using linear discriminant analysis (LDA) in order to obtain the most appropriate wavelet filter for detection task. A laboratory experiment is performed to validate the accuracy of the proposed method.

Early detection of unbalance voltage in three phase induction motor based on SVM

Unbalance voltage supply in induction motor is a crucial problem. This paper proposes an original system to detect an unbalance voltage condition in induction motor using Support Vector Machine (SVM). Induction motor current, as a signal due to the unbalance voltage supply in three-phase induction motor, is recorded in lab bench. The features of recorded signals are extracted by wavelet transform and Principal Component Analysis algorithm. Then, the quality of detection is classified by SVM, and the average result of detection is 86%.

Simulation-based analysis of short circuit fault in parallel-series type hybrid electric vehicle

There are many papers that propose diagnosis and fault detection in hybrid electric vehicles. However just a few of them con-cern in short circuit fault. In HEVs battery is one of the most crucial pars and can failure because of the short circuit due to several causes. In this paper, Matlab/Simulink Environment based hybrid powertrain system modeling and simulation for Toy-ota Prius HEV including short circuit case in DC bus system that is developed under SimPowerSystems and Sim- Driveline toolboxes is proposed. This is a multi-domain system which is composed of control system, electric power subsystem, and driving force subsystem. As for the short circuit model, it is developed according to the data collected from investigation report of Prius fire forensics. This hybrid powertrain is of series-parallel type and in order to increase drivetrain efficiency and reduce air pollution, It has two kinds of motive power sources: Internal Combustion Engine and Electric Motor. This system has the advantage of high dynamic performance and low pollution at low speeds coming from internal combustion engine and the ad-vantage of no-pollution and high available power at low speeds coming from electric motor drive. We present the short circuit analysis in DC electric supply system of HEV. The effect of short circuit to the HEV performance is analyzed.

Evaluation of distribution network reliability index using Loop Restoration Scheme

In this study, to evaluate the reliability of network distribution system at Gresik area, Loop Restoration Scheme method is applied. This method is used to control the distribution system on every feeder that has a function to increase the reliability of the system. After applying this method, the information of the reliability level can be obtained and hopefully it will make a good impact. With the LRS method implementation for the PLN distribution system, it will provide a good refinement to the value of reliability index and becomes key point for further application. The reliability index values during normal conditions of PT PLN configuration with the conditions after applying the method of LRS on the distribution system is compared and analyzed. From the result of applied system, it can be informed that the distance is quiet significant and has better results.

Electric double layer capacitor impact on the performance of Hybrid Electric Vehicle

In Hybrid Electric Vehicles (HEV), one of the most important phenomenon which has effect on the vehicle performance is certainly quality of power and power flow in the system. A good power quality in the system can be provided by decreased fluctuation in power flow and a longer life-time of the battery utilized in the electric subsystem of the vehicle. In this paper, we utilize a parallel-series type HEV simulation which is developed in Matlab/Simulink environment. In such type of HEVs, there are different operation modes. When switching between those operation modes, undesired power flow fluctuations occur. In order to smooth the power flow fluctuations and decrease the charge/recharge cycle times of battery, proposed Electric Double Layer Capacitor (EDLC) is developed and connected to battery pack in parallel in the simulation system. The impact of EDLC on the HEV performance can be seen clearly.

Analisis Karakteristik Arus dan Tegangan pada Inisiasi Feroresonansi Transformator Tegangan Rendah

Ferroresonance is an interaction phenomenon between non-linear inductance and capacitance that initiates abnormal waveform of current and voltage. This phenomenon is very sensitive to system parameter and initial condition. In this paper, ferroresonance initiation involved a basic circuit of series ferroresonance with variation of source voltage magnitude on a single phase low voltage transformer. The scheme of experiment was based on the case of transformer energizing. The trends of current and voltage waveform on the primary windings were investigated and transformed by using Fast Fourier Transform (FFT). The harmonics spectrum was then employed to identify the feroresonance mode and calculate the Total Harmonics Distortion (THD) of current and voltage. The experimental results showed that the higher source voltage magnitude caused the ferroresonance responses to be seen more clearly. It was indicated by the more distorted waveform, the higher odd harmonics frequency amplitude especially for 150 Hz, and the greater THD. Based on the harmonics spectrum and wave period, the ferroresonance responses were identified as fundamental mode. The effects of initial conditions, such as residual flux of transformer and capacitor charge, were also seen on the distorted wave peak during transient condition. In addition, the difference of waveform between normal and ferroresonance condition could be more easily observed on the voltage than the current. The waveforms of current and voltage during experiment had been verified by using simulation.

Estimation of residual flux in single phase transformer using dynamic modeling of two winding single phase transformer

This study deals with estimation of residual flux in 1 kVA 1-phase transformer. Transformers used in the study have two type core cutting topology. The transformers were modeled with MATLAB software and then simulated to obtained inrush current. Experiments were also done in order to obtain its inrush current with different demagnetization time. The result showed a difference between simulated inrush current result and experimental result, which influenced by the existing residual flux and not yet disappeared during demagnetization process on the core of the single-phase transformer. The result shows that different core cutting topology affects the residual flux as well as the time of demagnetization.

Core-cutting topology effects of single phase 1-KVA transformer on inrush current

This paper deals with core-cutting method effects of single phase 1-KVA transformer on its inrush current. Different core-cutting topologies of transformer which is EI and EE were studied. Finite-element method and equivalent circuit based simulation were done to understand its effect on inrush current of transformer. Equivalent circuit is used to obtain the peak value of inrush current. Meanwhile finite-element method simulation is used to understand the distribution of flux density and magnetic field intensity. The results show that inrush current value influenced by core losses. Moreover, it is shown that EI cutting topology gives lower peak value of inrush current.