Bambang Anggoro

Resistivity and Dielectric Constant Characteristic of Soil If are Treated by Water, Salt and Carbon

The characteristic of resistivity and dielectric constant of soil is the importance thing for investigating the impedance of grounding system. The impedance of grounding systems have resistance, inductance and capacitance components. Resistance and capacitance depend on resistivity and permittivity of soil and the configuration of electrodes of grounding system. The characteristic variation of resistivity and permittivity depend on the environment condition such as water, salt, chemical solution etc. In this experiment the soil is treated by water, salt and carbon with percentage variation from 2.5% to 15% and injected by low frequency of current (f=50 Hz). The calculation of resistivity and permittivity used the equivalent circuit of soil. Influence of characteristic of resistivity and permittivity depend on the type of soil

New probabilistic approach for identification event severity index due to short circuit fault

In this paper, it is introduced a new approach to identify bus voltage severity profile due to short circuit fault at a certain point in a distribution power system. Short circuit causes voltage decrement for duration of time related to opening time of a relay. Data containing 2 variables, depth and duration of voltage sag due to short circuit faults on every buses, are generated. Subsequently, these data from all of buses will be clustered using K-means Clustering. Clustering data will produce center clusters and cluster membership. To be able to perceive voltage sag severity, center clusters will be converted to Event Severity Index which explains severity of a voltage sag event based on CBEMA-ITI Curve. Data of a certain bus which undergoes voltage sag events will be classified based on its cluster membership or center cluster. Thus, it will be obtained frequency of events that are classified into particular clusters; how many events that is classified into particular clusters. In order to observe data well, it is better to present it making use of histograms.

The Influence of Resistivity and Dielectric Constant of Soil Which is Injected by Low to High Current Frequency

Grounding system in actual consist of electrodes configuration (vertical, horizontal, grid) and soil where these electrodes are planted. The grounding system which is installed to power systems or lightning protection system will be injected by low to high frequency. Electrical characteristic of soil (resistivity and dielectric constant) will be varied caused by injected current frequency variation. The variation of resistivity and dielectric constant depend on mineral composition of soil. As we know well that the soil constant of clay, silt, sand and gravel. Clay have an unstable chemical bonding and silt, sand and gravel have a stable chemical bonding, so if we have to know the type of clay for investigating the resistivity and dielectric constant of soil. In this experiment we used the soil with water treatment. Frequency of power supply is 0 Hz-13 MHz. The computation for investigating resistivity and dielectric constant used circuit equivalent of soil. Resistivity and dielectric constant will descend with frequency ascent, but the formulation of descending depends on the type of clay

Transformer end-of-life estimation using condition-Based Sampling Period Method

This paper discusses transformer end-of-life estimation using condition-Based Sampling Period method. Condition of the transformer is randomly generated. This condition will be used to determine the sampling period of the measurement data collected from sensors. The observation interval will be decreased if the condition of the transformer deteriorates fast. The tangent of the condition will be used to estimate transformer end-of-life. Simulation shows transformer end-of life can be estimated using this method and the next observation can be determined according to the gradient of condition.

Transformer performance calculation using information fusion based on DGA interpretation

This paper discusses about transformer performance calculation using information fusion algorithm. DGA data is interpreted using OMA3S information fusion to recognize fault occurring in the oil. Observed gas to be interpreted in this paper are hydrogen, acetylene, and carbon monoxide, since they are combustible. The result is used to find weight of each sensor to calculate performance. Information Fusion can be used to perform performance calculation using

Interpreting DGA Key Gas using Fuzzy OMA3S

This paper discusses about interpreting DGA key gas using Fuzzy OMA3S. DGA key gas data is compared to standard and put into condition group. Each group is given score and is assigned to the corresponding fault in the observation matrix. The next step is to calculate New Knowledge Probability Distribution (NKPD) on each observation, which is the maximum value of a group of sensors that indicates each hypothesis. To show Knowledge growth, NKPD over Time (NKPDT) is used. At the last observation, the hypothesis with the highest value of NKPDT becomes the DoC. The goal of this paper is to compare the crisp logic of the conventional OMA3S and the Fuzzy logic OMA3S in interpreting 6-sensor-4-hypothesis DGA.

The technical problems to modify low voltage winding of power transformer

The transformer is the main equipment in the electrical power systems to convert the potential from low voltage to high voltage or on the contrary. To build the real new transformer is easier than rewind and modify the old one, because have many technical constrains for solving these problems. The old transformer has the fix dimension for example length, width, depth of the casing and dimension of the magnetic core. The capacity and the high voltage of the “new” transformer still same with the old one is 20 MVA but only the low voltage is changed from 6 KV to 13.8 KV. The first step before modify the old transformer, we have to know well about the condition of this transformer by checked / measured the all electrical quantity. The detail calculation and construction of the low voltage winding with many constrain must be done well. After that to choice the material especially the wire for low voltage winding include the type of insulation, to make schedule and standard operation procedure of construction. At the last to test the vector group of voltage and to test all of electrical quantity include the energy losses of the “new” transformer.

Preliminary design of solar thermal power generation - Indonesia case study

As one of equatorial countries in the world, Indonesia has a great potency of solar energy. However, the utilization of this potency is still not optimal yet. In term of electric power production, the utilization of solar energy in Indonesia is currently mostly relied on photovoltaic modules. In this paper, a different approach of application of solar energy is presented. The design is based on solar thermal utilization. The objective of the design is to produce 10 MWe electric power by adopting a solar thermal power generation plant which suitable with Indonesia condition. In this preliminary design, it is obtained that the solar thermal-based power generation plant can be pushed to 25.29% in term of efficiency.

The induced current density calculation by charge simulation method for grounded and isolated man model exposed under 500 kV transmission line

The electric and magnetic fields always be produced by all electric apparatus and can induce the current induction in to human body. These induced current densities must be calculated/measured for determining the permission limit value of electric/magnetic fields, so we can define that the type of electric/ agnetic fields are dangerous to human being or not. The calculation of induced current densities in human body are done as result of electric field from 500 kV transmission line for grounded and isolated of man model, with the condition of ground surface without any tree or other object surronding the man model. Because of the character of model skin of the human body is conductive, so the result of this calculation for grounded and isolated is deference. For the grounded man model, the skin potential equals zero and the skin as equipotential surfaces. The illustration of the result are curved between induced current densities and section of the human body.

Characteristic study of two-layer vertical grounding system for variation of length rod and high frequency injection current (100kHz–14MHz)

Soil has unique characteristics when injected with currents. These characteristics depend on frequency and magnitude of current injection. Grounding system on power frequency consider only resistive properties. However at high frequency, the parameters not only used resistance; capacitance and inductance parameter must also be considered. In this research, testing method performed by measuring two-layer vertical grounding by injecting a low magnitude current (μA-mA order) and injection frequency between 100kHz to 14 MHz in three models of two-layer vertical grounding system. The result shows that at high frequency, three model has a significant increase in grounding impedance; for longer rod and higher frequency injection current, grounding impedance will be smaller.