Circuit Breaker Operation Research Articles

Staged-Fault Testing of Distance Protection Relay Settings

In order to analyze the operation of the protection system during induced fault testing in the Croatian power system, a simulation using the CAPE software has been performed. The CAPE software (Computer-Aided Protection Engineering) is expert software intended primarily for relay protection engineers, which calculates current and voltage values during faults in the power system, so that relay protection devices can be properly set up. Once the accuracy of the simulation model had been confirmed, a series of simulations were performed in order to obtain the optimal fault location to test the protection system. The simulation results were used to specify the test sequence definitions for the end-to-end relay testing using advanced testing equipment with GPS synchronization for secondary injection in protection schemes based on communication. The objective of the end-to-end testing was to perform field validation of the protection settings, including verification of the circuit breaker operation, telecommunication channel time and the effectiveness of the relay algorithms. Once the end-to-end secondary injection testing had been completed, the induced fault testing was performed with three-end lines loaded and in service. This paper describes and analyses the test procedure, consisting of CAPE simulations, end-to-end test with advanced secondary equipment and staged-fault test of a three-end power line in the Croatian transmission system.

Modeling Distribution Component Deterioration: An Application to Transformer Insulation

The two most critical components in a typical Power System are the circuit breakers and transformers. Failure of any of these components will result in high cost due to component replacement and associated load loss. Reliability Centred Maintenance (RCM) may reduce this cost in the long run by extending the component lifetime and increasing availability. This will be possible, since the adopted RCM will balance carrying out too much maintenance which will increase maintenance cost or too little maintenance that will result in catastrophic failure and hence increases the cost of maintenance and repair. A Markov model that relates probability of failure to maintenance activity is developed for distribution transformers. This model incorporates various levels of insulation deterioration and minor maintenance state. It was applied to one of the distribution transformers in Abule-Egba Business unit network of Power Holding Company of Nigeria. The result obtained from model simulation agrees with the one obtained from the mathematical analysis of the developed model. With an adjustment in the inspection parameter, this probabilistic deterioration model for a distribution transformer can also be applied to predict the performance of circuit breakers.

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.

$V\!{-}t$ Characteristics of Vacuum Interrupter After Large Current Interruption

Because of the contact material's evaporation and ejection of some metal particles out of the contact gap during the flow of the vacuum arc, the contact surface may exhibit some erosion after each operation of vacuum circuit breakers. In this paper, the insulation properties were investigated for vacuum interrupters with the rated voltage of about 10-kV operating voltage after short-circuit current interruption of more than 10 kA of 50-Hz current. The vacuum interrupter contacts were opened at either a current-zero point or an ac current peak. The latter involves greater arc energy at the short gap length compared with the former. After such interrupting duty, the characteristics were measured with the lightning impulse and rectangular impulse voltages as a function of polarity relative to that of the interrupting current. When the contact was opened at the current peak, the insulation properties deteriorated substantially compared with those of the new interrupter, and the polarity of the applied impulse voltage relative to that of the interrupting current has considerable effect.

Development process of impulse surface flashover on alumina dielectrics in vacuum

For higher electrical insulation performance of vacuum circuit breakers (VCB), the surface insulation characteristics in vacuum should be improved. In this paper, we investigated the development mechanism of impulse surface flashover on alumina ceramic insulator in vacuum. We measured the still images and ultra fast framing images of fast developing surface flashover in synchronous with applied impulse voltage and current waveforms. The light emission transition in initiation of surface flashover was also clarified. We found the dark area was formed around the cathode and conducting channel was formed from the anode in developing process of surface flashover in vacuum.

Assessing circuit breaker performance using condition-based data and Bayesian approach

This paper proposes a methodology to assess the performance of circuit breaker utilizing its control circuit data. Various performance indices are defined to assess the condition of breaker using probability distributions. Bayesian updating approach is implemented to update these indices as the new data becomes available. An approximation in implementing the Bayesian approach to deal with large amounts of data on-line is considered. The methodology is applied to data recorded at different times during both open and close operations on a group of similar circuit breakers. The methodology can be used to quantify the effect of maintenance making use of the defined performance indices, which further helps in developing system level risk-based decision approaches for maintenance optimization.

Pattern Recognition of Typical Incipient Mechanical Failures in Circuit Breakers

To detect circuit breaker mechanical failures that are still in their early stages in order to avoid more serious failures and ensure reliable and safety of the grid operation, we uses a type ZW17-40.5 35 kV circuit breaker to simulate three typical incipient mechanical failures about stagnation of the energy storage spring, the dowel on the connecting rod and the moving arc. This analysis uses a digital camera detection method to record the processes for normal circuit breaker opening and closing conditions and conditions under stagnation. Additionally, by using a specially developed software to extract travel, speed and acceleration of specific location in every frame, we can discover features of the mechanical failure from the resulting data. This article provides a basis for identifying characteristics of stagnation and state monitoring of circuit breakers.

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.

차단기 트립코일 이상감지 장치

The circuit breaker of power distribution board is essential part for the protection of electrical disaster from load short, trouble of power system. For the normal operation of circuit breaker, trip coil of the circuit breaker can cut the mechanical contact of circuit breaker from the detection of power system troubles.BR This paper presents a design and experimental results of trip coil fault detection system for the real time monitoring of the circuit breaker. The designed system is consisted by the trip coil fault detector which is connected to the each circuit breaker and remote monitoring unit. The trip coil fault detector can detect the impedance and operating voltage of the trip coil, and the detected values are compared with the normal state. And the remote monitoring unit can be connected to the 32 channels of trip coil fault detectors by serial communication. From the designed system, the fault and normal states of the trip coil can be remotely monitored in real time.BR The designed system is verified by the practical circuit breaker of power distribution board. And the results shows the effectiveness of the designed system.

Discussion of electrode conditioning mechanism based on pre‐breakdown current under nonuniform electric field in vacuum

AbstractElectrode conditioning is a very important technique for improvement of the insulation performance of vacuum circuit breakers (VCBs). This paper discusses the spark conditioning mechanism under a nonuniform electric field, focusing on the pre‐breakdown current. We quantitatively evaluated the spark conditioning effect by analyzing the pre‐breakdown current based on the Fowler‐Nordheim equation. The field enhancement factor β was found to decrease with increasing breakdown voltage at the beginning of the conditioning process, and finally became saturated with the saturation of the breakdown voltage. In addition, in the case of a nonuniform field, we found that β on a high‐voltage rod electrode after conditioning varied according to the electric field strength on the rod electrode. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(2): 21‐28, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21059

Solid-state fault isolation devices: application to future power electronics-based distribution systems

This study addresses the timely issues of modelling, and defining selection criteria for, a solid-state fault isolation device (FID) intended for use in power electronics-based distribution systems (PEDS). This work subsequently derives the FID parameters by mapping the characteristics of a conventional medium-voltage distribution system onto that of the PEDS envisioned under a new multi-university Engineering Research Centre. When conventional circuit breakers are used in distribution systems, they have a relatively long clearing time, causing the voltage to collapse for a significant time. A semiconductor circuit breaker, however, is expected to be able to switch fast enough to keep a voltage disturbance within acceptable limits. The main focus of this study is to address the operational issues of the interaction between the power electronic converters and the solid-state FID. The utilisation of rate of current decrease (di/dt) control during turn-off in conjunction with passive clamping devices to manage the overvoltage that results from very fast circuit breaker operation is introduced. In contrast to a simple conventional RC-snubber circuit, the proposed overvoltage management avoids high leakage current, which is the undesirable drawback of RC-snubber circuits. The presented prototype is experimentally verified with low and medium-voltage test circuits.

Arc-induced turbulent mixing in an SF6 circuit breaker model

Dielectric interruption performance of SF6 high-voltage gas circuit breakers depends on the temperature distribution of the gas during the post-arc phase. Understanding the details of the mixing process occurring inside the breaker during arcing is therefore fundamental for the design. Multiphysics simulations are nowadays used to predict the flow field and the energy distribution inside the interrupter during and after the arcing phase. In this paper we make use of an optical technique to observe the arc-induced SF6 mixing process inside a dedicated test device. We extract qualitative and quantitative information and we compare this with simulations to conclude on the suitability of the models used.

A Fault Diagnosis Method of Power Systems Based on Improved Objective Function and Genetic Algorithm-Tabu Search

Based on the improved optimization objective function of fault diagnosis, a genetic algorithm-Tabu search (GATS) method is introduced for the purpose of fault diagnosis of power systems. The genetic algorithm has good global search ability, while the Tabu search algorithm has good local search ability. Integrating the advantages of these two algorithms, a new hybrid algorithm, called GATS, can be obtained. Using the function of Shcaffer, the advantages of GATS are proven in this paper. The results of case studies show that GATS is superior to conventional methods in terms of the sensitivity of original solution and the dependency of original parameters. The satisfactory results can be obtained when the GATS method is applied in the event of abnormal operations of protective relays and circuit breakers or the multiple-fault scenarios.

Computation of Transient Electromagnetic Fields Due to Switching in High-Voltage Substations

Switching operations of circuit breakers and disconnect switches radiate transient electromagnetic fields within high-voltage substations. The generated fields may interfere and disrupt normal operations of electronic equipment. Hence, the electromagnetic compatibility (EMC) of this electronic equipment has to be considered as early as the design stage of substation planning and operation. Also, microelectronics are being introduced into the substation environment and are located close to the switching devices in the switchyards more than ever before, often referred to as distributed electronics. Hence, there is the need to re-evaluate the substation environment for EMC assessment, accounting for these issues. This paper deals with the computation of transient electromagnetic fields due to switching within a typical high-voltage air-insulated substation (AIS) using the finite-difference time-domain (FDTD) method.

Effects of Reclosing for Insulation Coordination in 345kV Combined Transmission Lines

This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with XLPE power cable. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as length ratio of power cable section, arrestor, inserting resistance, charging rate, grounding resistance, etc.. On the other hand sheath voltage on IJ(Insulated Joint) is analyzed to check dangerous condition on cable cover. Analysis is performed by EMTP/ATP. Analysis results show that reclosing can be operated as the single line-to-ground fault occurs on overhead line in 345kV combined transmission line, if the inserting resistance is considered before the operation of main circuit breaker.

Influence of surface charges on impulse flashover characteristics of alumina dielectrics in vacuum

For higher electrical insulator performance of vacuum circuit breakers (VCB), the surface flashover in vacuum should be improved. In particular, it is important to clarify how strongly surface charges influence the surface flashover mechanism. In this paper, we investigated the surface flashover characteristics based on the existence of surface charges on an alumina insulator in vacuum. We changed the location and magnitude of surface charges and measured surface flashover voltage. From our experimental results, an attempt was made to clarify the influence of charges on alumina dielectrics on impulse surface flashover characteristics in vacuum. From this, we concluded that (1) when surface charges were located near the cathode electrode, a positive charge made the surface flashover voltage lower and a negative charge made the surface flashover voltage higher; and, (2) when surface charges were located in the way of the discharge path, both positive and negative charges made the surface flashover voltage lower. We were able to explain these results by considering the influence of surface charges on the electric field at flashover and on the secondary electron emission avalanche.

Measured turbulent mixing in a small-scale circuit breaker model

The performance of high voltage gas circuit breakers depends on the temperature distribution of hot gas or plasma from the arc zone mixed with cold gas that is present, for example, in the exhausts and mixing volume. Understanding the details of the mixing process is imperative to estimate the temperature distribution within the entire breaker volume. Design studies rely on computational fluid dynamics (CFD) simulations to search for the best way to achieve satisfactory mixing. One key uncertainty in the CFD simulations is the role of turbulence in this process and how to properly account for it. To gain knowledge of the mixing process between hot and cold gases, we have constructed a simplified breaker geometry that is flexible and accessible to diagnostics. Apart from standard measurements of current and arc voltage, we measure pressure in the arc zone and the mixing volume. Further, the mixing volume is specially designed to be transparent, allowing us to make shadowgraphy measurements of the turbulent mixing during and after the arcing phase. We report on experiments performed in air at atmospheric pressure.

Evaluation on Short Line Fault Breaking Performance of SF$_{6}$ Gas Circuit Breaker Considering Effects of Ablated Nozzle Vapor

In this paper, short line fault breaking performance of SF6 gas circuit breaker was evaluated by calculating the post arc current and the temperature on arc axis. For the analysis of arc-gas flow, finite volume fluid in cell method was used to solve governing equations. In arc modeling, finite element method and the method of partial characteristics were used for the calculation of Joule heating and radiation model, respectively. Also, the effect of ablated nozzle vapor was considered in the simulation. The calculated results were compared and confirmed with the experimental values.

Hybrid Model for Cascading Outage in a Power System: A Numerical Study

Analysis of cascading outages in power systems is important for understanding why large blackouts emerge and how to prevent them. Cascading outages are complex dynamics of power systems, and one cause of them is the interaction between swing dynamics of synchronous machines and protection operation of relays and circuit breakers. This paper uses hybrid dynamical systems as a mathematical model for cascading outages caused by the interaction. Hybrid dynamical systems can combine families of flows describing swing dynamics with switching rules that are based on protection operation. This paper refers to data on a cascading outage in the September 2003 blackout in Italy and shows a hybrid dynamical system by which propagation of outages reproduced is consistent with the data. This result suggests that hybrid dynamical systems can provide an effective model for the analysis of cascading outages in power systems.

Thermal radiation effect on the extinction properties of electric arcs in HV circuit breakers

During the formation of the electric arc at the opening of a high voltage circuit breaker, the generated plasma will be the seat of a very important thermal exchange. Models founded only on conduction and convection thermal transfers don't reproduce the whole thermal exchanges that are governing the extinction process. This paper is devoted to the development of a model of the electric arc extinction in a high voltage circuit breaker taking in account the thermal radiation of the plasma, in addition to the conduction and convection phenomena. The Stefan-Boltzman equation is coupled with the heat equation, and both equations are solved simultaneously in order to follow the evolution of the arc voltage and the conductance of the thermal plasma. The obtained results are found in good agreement with experimental recordings.