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A new approach for the modeling of transformers and transformer banks in three-phase distribution networks is proposed. The approach considered is mainly focused on transformers and transformer banks with different electrical characteristics and tap positions for each of the single phase transformers forming this bank. The definition of individual transformer ratio matrices for different vector groups...
Occurrences of faults in power system contribute extensive voltage sags (dips) in a network. These occurrences have introduced problems to consumers mainly at 415V where sensitive control equipment is located. This paper investigates the propagation and travelling of voltage sag event under the influence of transformer connections and impedance line length. PSS/ADEPT (Power System Simulator Advanced...
As affected by electromagnetic coupling, the sequence impedance of parallel multi-circuit cable lines is different from that of single-circuit ones. Based on “conductor-ground” loop, derived from the matrix form of voltage equations, a new algorithm of parameters calculation for multi-circuit cable lines is presented. To consider the influence of metal sheath, the algorithm treats it the same as core...
The aim of this paper is to calculate the response of grounding system under high-magnitude fault current accurately. In this work, A FEM model is presented to solve the problem in frequency domain. The ionized phenomenon in the soil around the grounding electrode is taken into account by setting the resistivity of every soil element varying with the electric field intensity. Open boundaries of earth...
According to the obvious transient characteristics at the beginning of the fault in the non-effectively grounding distribution system, a new method, based on Hilbert-Huang transform(HHT), is proposed to extract the non-power frequency transient current from the zero-sequence current in distribution networks with a single-phase-to-earth fault. HHT is used to get the amplitude and phase angle of the...
We investigate an approach of accommodating new logic relations, represented in Markov Logic Networks (MLN), from a source domain to a target domain automatically. One characteristic of this problem setting is that logic relations, which are expressed as logic formulae, previously prepared for the source domain dealing with a text mining application are not sufficient for the target domain. Therefore,...
This paper presents practical aspects of a computational implementation based on the Transmission Line Modeling Method in one dimension (TLM-1D) for the transient analysis of grounding electrodes. Initially, an introduction on the subject with a brief revision of the state-of-the-art methodologies currently used for impulsive grounding transient evaluation is made, emphasizing TLM. In the following,...
Earth resistance is a one of the most important issues for wind turbine lightning protection. Although various equations have been proposed to simulate earth resistance, it is still difficult to accurately estimate an actual wind turbine earth impedance because of its complex shape combined with a concrete foundation, auxiliary vertical and ring electrodes. This report clarified how the shape and...
The paper deals with transient analysis of ring shaped grounding electrodes using isoperametric quadratic elements. The formulation in the frequency domain is based on the thin wire antenna theory and the related Pocklington integro-differential equation while the corresponding transient response is obtained by means of the Inverse Fourier Transform (IFT). The Pocklington integro-differential equation...
This paper presents a comprehensive optimization method for the diagnosis of large substation steel grounding grid integrity status, and the detection and location of any corrosion spot before digging out the grounding grid. A grounding grid is modeled as a circuit network, and fault diagnosis equations are derived by applying Tellegen's theorem, optimization theory and fault diagnosis theory for...
The single-phase grounding fault line selection in the distribution network has always been an outstanding problem of power system relay protection. One of the key reasons for fault line selection difficulty is that the fault current is correspondingly too weak to be detected effectively for the small current grounding system which is widely adopted in our distribution networks. The paper mainly discusses...
According to the obvious transient characteristics at the beginning of the fault in the non-effectively grounding distribution system, a new method for selecting the fault line, based on Hilbert-Huang transform (HHT), is proposed to extract the non-power frequency transient current from the zero-sequence current in distribution networks with a single-phase-to-earth fault. HHT is used to get the amplitude...
The grounding system is made of steel in most of developing countries. When the steel is eroded, it is a potential problem and very dangerous to the power system. So, the fault diagnosis on grounding grids is of great economic value for the safety operation in electric power system. In this paper, a simulation computation method is presented by means of a nonlinear model. Via this method, the real...
This paper presents a review study on state of the art techniques used for electromagnetic transient studies on grounding systems. First, an introduction about the subject is presented, emphasizing the importance of grounding in population safety and equipments protection. Following, the Circuit Approach, Transmission Line Approach, Electromagnetic Field Approach and Hybrid Approach are reported....
This paper establishes a unequal potential grounding grid model which is different from previous model where the grounding grid is equivalent to a electric network composed of resistors, based on the principle of uniting field and circuits while considering the resistor, self-inductance, mutual inductance and leakage current of inductor .In this model ,the corrosion diagnosis equation is setting up...
The steel grounding grid buried in earth will corrode and become hidden danger to the safety of power system. It is important to examine the state of grounding. Particle swarm optimization (PSO) is a population-based, self-adaptive search optimization technique. This paper used combination of rotating and encouraging each location and incentives, many measurement method, established a new non-linear...
Statistical Relational Learning (SRL) is a growing field in Machine Learning that aims at the integration of logic-based learning approaches with probabilistic graphical models. Markov Logic Networks (MLNs) are one of the state-of-the-art SRL models that combine first-order logic and Markov networks (MNs) by attaching weights to first-order formulas and viewing these as templates for features of MNs...
The analysis of complex grounding systems has been undertaken using the wire antenna model and the set of Pocklington integro-differential equations for curved wires. The corresponding integro-differential realtionships are numerically handled via the Galerkin-Bubnov scheme of the Indirect Boundary Element Method (GB-IBEM). Frequency dependent input impedance is obtained as a ratio of voltage and...
This paper proposes a mathematical model for the analysis of safety conditions at a transmission-line tower located in close proximity to the substation, of which the line is connected to, arising in the case of a single-phase-to-ground fault at the tower. The model takes into account the mutual interaction of the substation and tower ground electrodes affecting the currents discharging from these...
Grounding grid is commonly installed in the substation. When it's damaged, not only restoring and improving work affects the production, but also it is difficult to carry this work out. In this paper, a new nonlinear constraint optimization model is established in order to find out the corrosion and abruption of the grounding grid. Due to the characteristics of grounding grid fault diagnosis, a combined...
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