High Voltage Circuit Breaker Research Articles

Adjustment in the Least Square Meaning of a Neural Model for Electric Arc Quenching in High Voltage Circuit Breakers

Adjustment in the Least Square Meaning of a Neural Model for Electric Arc Quenching in High Voltage Circuit Breakers

초고압 SF6 가스 차단기 투입 시 아크접촉자 내전압 특성 연구

The non-controlled closing of High-voltage SF6 gas circuit breaker can cause transient current and overvoltage in the field. The controlled closing technology is an effective way to reduce transient current and voltage, prevent equipment failures, and improve power quality. For the development of controlled closing, it is obviously necessary to determine the withstand voltage between arc contacts of High-voltage SF6 gas circuit breaker in making operation. This paper focuses on decrease of pressure and density of SF6 gas that can affect withstand voltage between arc contacts in making operation. The dielectric strength between arc contacts could be improved by minimizing the decrement of pressure and density of SF6 gas obtained by simulation and test and moreover the rate of decrease of dielectric strength (RDDS) of arc contacts could be foreseen.

Turbulence and Magnetic Field Calculations in High-Voltage Circuit Breakers

In high-voltage circuit breakers (HVCBs), the representation of convection is essential to provide a satisfactory description of the pressure increase in the heating volume or thermal expansion chamber. The plasma flow is mainly governed by Lorentz forces and turbulence effects. The Lorentz forces depend on the self-induced magnetic field which can be calculated by several approaches. A mixing formulation based on resolving the potential vectors and a Biot-Savart integral for the boundary condition is applied. The difference between this formulation and a null flux boundary condition is illustrated. The mixing formulation gives similar results to the use of Biot-Savart over the entire domain but is much less time consuming. To represent turbulence, one of the most frequently used models is the Prandtl mixing length model (PMLM). Nevertheless, recent works have demonstrated that the realizable model (RM) must represent the flow behavior in the heating volume. Such a model was applied and compared to the PMLM over the entire HVCB domain. The RM is clearly suitable to describe the turbulence in HVCB geometry.

New Method of Diagnosis and New Knowledge Acquirement for Fault Diagnosis Expert System of High Voltage Circuit Breaker

In this paper, an improved algorithm of general radial basis (RBF) function neural network is introduced, based on improved algorithm, the neural network realized quickly fault diagnosis and self-update of neural network structure, and the neural network is applied to the on-line fault diagnosis expert system. The expert system deals with the fault data that send from on-line monitoring equipment by using neural network, and it can discover the fault type and give reasonable solution by forward reasoning. Meanwhile, the expert system has the ability of achieving new knowledge based on the application of self-update ability of RBF neural network.

CFD Simulation of Transonic Flow in High-Voltage Circuit Breaker

A high-voltage circuit breaker is an indispensable piece of equipment in the electric transmission and distribution systems. Transonic flow typically occurs inside breaking chamber during the current interruption, which determines the insulating characteristics of gas. Therefore, accurate compressible flow simulations are required to improve the prediction of the breakdown voltages in various test duties of high-voltage circuit breakers. In this work, investigation of the impact of the solvers on the prediction capability of the breakdown voltages in capacitive switching is presented. For this purpose, a number of compressible nozzle flow validation cases have been presented. The investigation is then further extended for a real high-voltage circuit breaker geometry. The correlation between the flow prediction accuracy and the breakdown voltage prediction capability is identified.

The Study of Fault Diagnosis the High-Voltage Circuit Breaker Based on Neural Network and Expert System

An intelligent fault diagnosis system based on neural network and expert system integration is studied. The system uses neural networks to acquire fault codes and the corresponding type of fault, which are stored the knowledge base. In fault diagnosis, the expert system uses fault codes that can be found the corresponding fault type from the knowledge base through forward reasoning, and gives a reasonable solution. Meanwhile, this system also overcomes some shortcomings that the neural network doesn’t have functional and expert system has difficult to acquire knowledge. Used neural network and expert system in high-voltage circuit breaker fault diagnosis, the simulation indicates that this method is effective and feasible.

Application of Computational Fluid Dynamics to Reduce the New Product Development Cycle Time of the ${\rm SF}_{6}$ Gas Circuit Breaker

This paper describes thermal modeling, using computational fluid dynamics (CFD), to predict the temperature rise of a high-voltage SF6 gas circuit breaker during a heat-run test. In electrical equipment, maximum temperature rise in various components is limited by their material properties and, hence, the heat-run test forms part of type test. A methodology to predict the temperature rise at the design stage is developed using ANSYS-CFX and found to be beneficial to reduce the number of heat-run tests during the product development process. The developed methodology has been implemented on a 72.5-kV SF6 gas circuit breaker and validated with the experimental temperature rise results of the existing design at two current ratings: 1000 A and 2000 A. The methodology was further used to predict thermal performance of the breaker at a higher current rating of 3150 A. The prediction helped to understand temperature rise in various components and hot-spot locations. Various design modifications were then tested virtually to evaluate the temperature rise. Thereafter, the final modified design where the temperature rise of all the components was within the permissible limits and which also satisfied other constraints of manufacturing feasibility and cost was fabricated and physically tested. Good agreement is found between the CFD and experimental results.

“Survival of the fittest” — EMC in electric power substations

When a short circuit occurs in a transmission substation (usual definition - voltages above 100,000 volts), the resulting fault current is spectacular. In some substations, it may be as high as 80,000 amperes. Let's assume the fault was caused by the flashover of a porcelain insulator supporting a section of the high voltage power line a few towers away from the substation, due to a buildup of sea salt. The protective relays monitoring this transmission line detect this abnormally high current, and close their “trip” contacts - which then cause both the high voltage circuit breakers connected to this transmission line to open - and thus “clear the fault”. But while the fault exists, this high current is flowing from the tower to ground, then through the earth back to the substation. And since there is a finite (non-zero) resistance to “true earth ground”, this causes the entire substation ground matt voltage to rise. However, this is a 60 Hertz voltage, and adequate insulation - in control circuits and electromechanical protective relays - for this well recognized “ground potential rise” has been defined for years in protective relay standards (e.g. ANSI C37.90).

Development of the Control System and Communication Network for Intelligent SF6 High Voltage Circuit-Breaker

This paper analyses the cause of the major faults of the SF6 high voltage circuit breaker, and then introduces a solution using an embedded control system. The control system consists of the controller for every breaker and a supervisor control system in the control center. Then a double-annular fiber field-bus communication network for the control system is introduced, of which the data link layer is implemented by the CAN controller. According to the operation state of every node and the fiber, the fiber communication module of every node can be configured to several different transmission modes. Due to the influence of temperature, the empirical formula of Beattie-Bridgman is used to calculate the pressure of SF6.

Numerical simulation of arc extinction processes in a high-voltage current breaker

A new technique for calculating processes in the arc extinguishing device of an SF6 gas high-voltage circuit breaker is presented. Results of calculations and experiments are compared.

Transport properties of CF3I thermal plasmas mixed with CO2, air or N2 as an alternative to SF6 plasmas in high-voltage circuit breakers

This paper is devoted to the calculation of equilibrium compositions, thermodynamic properties (mass density, enthalpy and specific heat at constant pressure) and transport coefficients (viscosity, electrical conductivity and thermal conductivity) of air/CO2/N2–CF3I mixtures. These data are computed in the temperature range 300 K–50 kK and pressure between 1 and 32 bar. Results obtained for pure gases (CF3I, CO2, air and N2) are systematically compared with SF6. Transport coefficients for N2, CO2, CF3I and mixtures of CO2, N2 or air with CF3I are also confronted with previous published values. Particular attention is paid to the collision integral database by the use of the most accurate and recent cross-sections or interaction potentials available in the literature.

Flow Behavior in High-Voltage Circuit Breaker

Since several years, high-voltage circuit breakers (voltages of up to 800 kV) have been studied by the thermal plasma community to attain high level of reliability, good operating economy, and long intervals without maintenance. The studies are also related to gas substitution in order to replace SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> . This feature consists to study, by a numerical tool (@Fluent) in a specific geometry, the main physical mechanisms occurring during the current intensity variation. Images of the SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> plasma in the reactor are presented: geometry, temperature, and pressure fields.

Heat transfer in a high-voltage vacuum circuit breaker

Thermal performance is one of the key issues of the high-voltage vacuum circuit breaker (HV VCB). However, temperature rise of a HV VCB cannot be estimated easily. This article studied heat transfer of a 126-kV/2500-A single break VCB. A three-dimensional electro-thermal coupling model of the VCB was built, where the power loss was calculated by the electro-magnetic field analysis, and was then used as the input data to predict the temperature rise for the thermal analysis. The heat transfer coefficients on the boundaries were numerically calculated by a commercial software. The electrical contact resistance as well as the thermal contact resistance was taken into account in the electro-thermal coupling model. The simulated results were validated experimentally. The results showed that power losses of conductors enveloped in the vacuum interrupter took up 63.3 per cent of the total power loss of the VCB. Thermal resistances of conducting rods were the highest. The second highest was thermal resistance of a pair of main contacts. The thermal contact resistance significantly affected temperature at two conductors where there is a contact guaranteed by springs. However, temperature of the conductors exposed in the air was only affected by the natural convection and radiation.

Linking a physical arc model with a black box arc model and verification

The arc behavior in the current zero region is critical in the case of very steep rising TRV, such as after clearing a short-line fault. Therefore, intensive and abundant short-line fault tests (L90) of a 245 kV SF6 circuit breaker were performed at the KEMA High Power Laboratory. For the purpose of a comparative analysis three different sets of data were obtained during the tests: 1) High-resolution measurements of near current-zero arc current and voltage were carried out. The current zero measurement system (CZM) works as a standalone system in addition to the standard laboratory data acquisition system. The arc conductance shortly before current zero and the arc voltage extinction peak give a clear indication of the interrupting capability of the breaker under test. 2) From the measured traces of every individual test, arc parameters (3 time constants and 3 cooling-power constants) were extracted for the composite black box arc model, which has been developed by KEMA High Power Laboratory and is based on more than 1000 high-resolution measurements during tests of commercial high-voltage circuit breakers. Its aim is to simulate interruption phenomenon in SF6 gas, evaluate performance of HV SF6 circuit breakers in testing and enable the prediction of the performance under conditions other than those tested. 3) After each test, using specially developed computer software, based on a simplified physical enthalpy flow arc model, the values of the arcing contact distance, gas mass flow through the nozzle throat and pressure inside the compression cylinder were calculated. The values of these characteristic quantities at the current zero are relevant indicators for successful interruption. In the comparative analysis, mathematical relations and statistical correlations between the evaluated parameters of the composite black box arc model and the characteristic output quantities are established and discussed. The link has been verified by MatLAB simulation of every individual test. This approach enables acceptable prediction of interruption success in a similar circuit and with a similar interrupter without SLF tests and CZM.

An Adaptive Approach Based on KPCA and SVM for Real-Time Fault Diagnosis of HVCBs

High-voltage circuit breakers (HVCBs) play an important role in power systems, which can control and ensure the power grids are working properly. Real-time fault diagnosis of HVCBs is an essential issue for power systems. In this paper, a novel approach based on an adaptive kernel principal component analysis (KPCA) and support vector machine (SVM) is proposed for real-time fault diagnosis of HVCBs. In the proposed approach, a sample reduction algorithm based on a similarity degree function is proposed to analyze the similarity between the samples, and the redundant data can be eliminated. An adaptive KPCA method is used for the fault detection of HVCBs based on squared prediction error statistics. An SVM is used to carry out the fault recognition. Two spare data areas are set up for fault detection and recognition modeling. The data in the spare date areas are updated continuously, and the detection and recognition models are updated subsequently to improve the adaptivity of the diagnosis models and reduce the diagnosis error. The proposed approach can deal with various situations of the fault diagnosis for HVCBs. The experimental results show that the proposed approach is capable of detecting and recognizing the faults efficiently.

A Novel Smart High-Voltage Circuit Breaker for Smart Grid Applications

In this paper, we propose a new “intelligent operation” concept for high-voltage SF6 gas circuit breakers, in which the moving contacts are self-adaptively controlled from one position to an adjacent position to improve the circuit breaker life cycles. To analyze the concept intelligent operation, a new model of high-voltage SF6 gas circuit breaker is developed, and the moving characteristics of the new type circuit breaker are computed based on the newly designed model. Then both mechanical and electrical wears are quantitatively analyzed according to the breaker's new moving characteristic. Finally, we demonstrate the life cycle improvement of the new type of high-voltage SF6 gas circuit breaker. Our analysis can also be used to estimate the remaining life cycle of a breaker based on the tallied data collected by our intelligent modules.

Application of Genetic Algorithms on Parameter Estimation of HVDC Circuit Breaker

In order to estimate the parameters of capacitance, inductance and resistance in oscillation circuit DC circuit breaker a method of parameter estimation of High-Voltage circuit break based on genetic algorithms is proposed and which can properly assess the performance of DC circuit breaker. In this paper A genetic algorithm is introduced and applied in parameter estimation of High-Voltage circuit breaker and then compare it with the traditional MATLAB curve fitting, the result clearly reveal the advantages of genetic algorithm.

Support vector machine with genetic algorithm for machinery fault diagnosis of high voltage circuit breaker

Based on empirical mode decomposition (EMD) method and support vector machine (SVM), a new method for the fault diagnosis of high voltage circuit breaker (CB) is proposed. The feature extraction method based on improved EMD energy entropy is detailedly analyzed and SVM is employed as a classifier. Radial basis function (RBF) is adopted as the kernel function of SVM and its kernel parameter γ and penalty parameter C must be carefully predetermined in establishing an efficient SVM model. Therefore, the purpose of this study is to develop a genetic algorithm-based SVM (GA-SVM) model that can determine the optimal parameters of SVM with the highest accuracy and generalization ability. The classification accuracy of this GA-SVM approach is tried by real dataset and compared with the SVM, which has randomly selected kernel function parameters. The experimental results indicate that the classification accuracy of this GA-SVM approach is more superior than that of the artificial neural network and the SVM which has constant and manually extracted parameters.

TRV Rating Concepts and Generation of TRVEnvelopes for Synthetic Testing of Extra HighVoltage Circuit Breakers

Development in electrical power transmission system requires the use of circuit breakers with increasing breaking capacity. At present circuit breakers are to be installed on 245 kV to 1200 kV power system with short circuit ratings up to 120kA. To test high voltage CBs, direct testing using the power system or short circuit alternators are not feasible. The testing of high voltage CBs of larger capacity requires very large capacity of testing station. To increase testing plant power is neither an economical nor a very practical solution. Synthetic testing is an alternative equivalent method for testing of high voltage circuit breakers and is accepted by the standards. This paper presents a TRV rating concepts , IEC standards TRV envelopes and types of synthetic test circuits and their comparison. Analysis and mathematical modeling of 4-parameters TRV synthetic test circuit is done. A 4- parameters TRV synthetic test circuit based on parallel current injection method is designed and simulated for testing 420kV and 800 kV rating circuit-breakers as per new TRV requirements given in IEC 62271-100(2008).

Comparison of Two Models for Radiative Heat Transfer in High Temperature Thermal Plasmas

Numerical simulation of the arc‐flow interaction in high‐voltage circuit breakers requires a radiation model capable of handling high‐temperature participating thermal plasmas. The modeling of the radiative transfer plays a critical role in the overall accuracy of such CFD simulations. As a result of the increase of computational power, CPU intensive methods based on the radiative transfer equation, leading to more accurate results, are now becoming attractive alternatives to current approximate models. In this paper, the predictive capabilities of the finite volume method (RTE‐FVM) and the P1 model are investigated. A systematic comparison between these two models and analytical solutions are presented for a variety of relevant test cases. Two implementations of each approach are compared, and a critical evaluation is presented.