Rating Of Circuit Breakers Research Articles

Analysis and Detection of Power System Network Faults with Wavelet Transform

Fault detection technique is important for enhancing protection, stability, reliability and continuity of supply. There are many fault detection techniques implemented in power system such as Fourier transform, wavelet transform, neural networks, etc. This research presents the fault identification and analysis using wavelet transform method as well as estimation of circuit breaker rating. The discrete wavelet transform is implemented for the fault identification in five bus system. Various types of line and ground faults have been considered and studied using Daubechies wavelet function. The first level decomposition is used for the fault analysis. The maximum detailed coefficients for various faults currents are analysed for the fault identification. The wavelet transform algorithm is implemented using MATLAB programming. The five-bus system is modelled in MATLAB Simulink and various faults are simulated. The switching time of fault is taken as 0.05 to 0.1 seconds. The faults have been studied at different points in the system. The fault identification method gives accurate results for different types of faults. The load flow analysis is also done for five bus system and appropriate rating of circuit breaker is estimated.

Surge Current Interruption Capability of Discrete IGBT Devices in DC Hybrid Circuit Breakers

The power electronic interrupter (PEI) determines the current interruption rating of the dc hybrid circuit breaker (HCB). This paper deals with discrete insulated gate bipolar transistor (IGBT) based PEI modules. The influence of the voltage clamping circuit (VCC) on the surge current interruption capability (SCC) of the discrete IGBT is unveiled for the first time. Two commonly used VCC configurations are considered: a purely MOV based voltage clamp and an MOV-RC combination clamp designated as type I and type II PEI modules respectively. Comprehensive measurements are used to analyze the device turn-off behavior under each PEI module type to determine their limitations as well as their failure modes. The type I PEI is limited by the turn-off thermal stresses arising from the hard switching dynamics. The type II PEI, on the contrary, has the potential to achieve lower turn-off energy among other benefits but exhibits a unique failure mode during the tail current stage. Therefore, static and mixed-mode Technology Computer-Aided Design (TCAD) device simulations are introduced to provide further insights into the internal processes that alter the type II turn-off and in turn explain the failure mechanism. Finally, the influence of the various circuit parameters on the turn-off process are evaluated and methods to enhance the SCC of the IGBT based PEI are presented.

Resistive SFCL Integrated Ultrafast DC Hybrid Circuit Breaker for Subsea HVDC Transmission Systems

High voltage direct current (HVdc) power transmission systems do not encounter any natural zero crossing unlike the ac systems, and hence, the dc circuit breakers employed should be fast-acting and reliable to ensure safe operation. Circuit breakers (CBs) that have fast response time with lower energy loss dissipation are required for subsea HVdc transmission systems. This article investigates the performance of various CB topologies, including ultrafast coupled inductor hybrid CB (CIHCB) topology without and with the integration of resistive-type superconducting fault current limiter (R-SFCL) for a 100-kV, 100-MW HVdc transmission systems. It is found that the addition of R-SFCL with 1.7-ms response time decreases the peak current through the breaker and, hence, the power dissipated in the CB during short-circuit fault conditions. Thus, the rating of CB can be significantly decreased with the proposed topology. Furthermore, a comparison of power loss in CIHCB with the existing topologies, such as mechanical CB, resonant CB, and HVdc-hybrid CB, are also presented in this article.

Modelling of Resistive Type Superconducting Fault Current Limiter for HVDC Grids

The protection of high voltage direct current (HVDC) grids is a challenge considering that the protection system must detect, locate, and interrupt large fault currents in a few milliseconds. Resistive type superconducting fault current limiters (R-SFCL) can help solve that difficult task, reducing the extremely demanding ratings of HVDC circuit breakers. This paper presents different approaches to model R-SFCLs in order to analyze their suitability for assessing the performance of HVDC grid protection, including the step model, the exponential model, the RQ model, and the magneto-thermal model. In the first instance, the R-SFCL models are evaluated in a test grid to analyze their parameterisation and select the most adequate model for the study of HVDC grids. The RQ model is finally chosen for its simplicity but closer behavior to the magneto thermal model in terms of fault resistance dependency and resistance evolution curve. Then, the performance of an RQ type R-SFCL model in conjunction with a mechanical circuit breaker is evaluated in a multiterminal HVDC grid with different fault cases. This way, fault currents are greatly decreased as well as circuit breaker requirements. Hence, the R-SFCL under study enables a reliable protection of the HVDC grid.

Short-Circuit Fault Current Modeling of a DC Light Rail System with a Wayside Energy Storage Device

This paper proposes a simulation model to calculate short-circuit fault currents in a DC light rail system with a wayside energy storage device. The simulation model was built in MATLAB/Simulink using the electrical information required to define a comprehensive DC traction power rail system. The short-circuit fault current results obtained from the simulation model were compared with hand calculation results obtained using EN 50123-1 guidance. The relative error was 1.02%, which validates the model. A case study was carried out for a 1500 V DC light rail system. In the case study, a method was proposed to assess the DC protection and the withstand and breaking capacity of the DC circuit breakers for maximum current and distant faults. A traction power modeling simulation was conducted for the 1500 V DC light rail system to calculate the maximum load current in the analyzed electrical sections. It is concluded that the proposed simulation model and fault methodology can be used for DC protection settings calculations and DC circuit breaker rating analysis.

Development of Pec Based Electrical Load Schedule Software

This paper presents the development of PEC-based electrical load schedule software for residential electrical services design. All the sources that will be used for the computation and data will be based on PEC. The testing of the project will be carried out in accordance with PEC as well as other approved codes. Calculating tools to help you understand the process of accurately sizing a commercial electrical panel based on proposed loads. To emphasize, accurate load sizing is best performed by an electrical engineer, which is reviewed by the building department in your jurisdiction. The software was developed using Visual Basic (VB. net) programming language. Vb.net, or Visual Basic, is a development of the BASIC programming language. It is intended to be used in conjunction with an Integrated Development Environment (IDE). Prior to the development of IDEs, programming languages like BASIC relied significantly on the DOS command-line. A load schedule for different operating scenarios will show when peak consumption occurs and provide an opportunity to find out if all the high loads must operate at this time. It serves as a valuable calculation tool for electrical engineers, students, and technicians by providing a faster, easier, and more accurate means of carrying out some basic calculations, such as determination of the size of wire; conduit sizes; circuit breaker ratings; the main feeder size of wires; main circuit breaker ratings; voltage drop; and riser diagram using Philippine Electrical Code Tables. The results of these calculations help the designer to make vital decisions such as cable sizing and nominal ratings of protective devices required by each circuit and by the entire installation, in line with appropriate standards and regulations.

Optimal Allocation of Distributed Generation Units Correlated With Fault Current Limiter Sites in Distribution Systems

Integration of distributed generating (DGs) units helps in reducing the extreme loading on the main power grid. DGs are convoyed with high fault currents. High fault currents exceed the ratings of circuit breakers. This article proposes optimal allocation of different types of DGs units correlated with fault current limiters (FCLs) in single stage. The proposed method is assessed with two-stage approach that is carried out based on coyote optimization algorithm (COA) and electrical transient analyzer program (ETAP) at normal and faulty operating conditions, respectively. For this target, a fuzzy-based multiobjective (FBMO) formulation is proposed for enhancing the distribution system performance in both operating conditions. It aims at minimizing the power losses, reducing the fault currents in the network with economizing the installed FCLs sizes. To handle FBMO formulation, the COA has been employed to search for the optimal combination between DGs and FCLs. The proposed methodology is studied on IEEE 33-bus, 69-bus, and the Egyptian East Delta distribution systems. Acceptable power losses and fault level reduction are achieved for normal and faulty operating conditions. Therefore, the effectiveness and capability of the employed single stage for DG units correlated with FCLs allocation are proved compared with bistage approach.

Electric Power System Fault Analysis

Fault analysis is an important aspect in the successful operation of a power utility grid. The occurrence of faults in the system is not avoidable as causes of faults are not particularly one but of many with different causes and nature. It is one of the most important as well as it one of the most complex tasks in power engineering. The studies and discovery of faults in electric power systems is essential in ensuring the consistency and the stability if the power grid. Another importance of carrying out fault analysis gives a fair idea of the voltages and the current magnitudes under faulty conditions for different scenarios. This is helpful in the design of protection devices such as fuses, circuit breaker ratings, over current protection relays and other devices that are used for the protection of the system. Protection devices are important features of the power system grid mainly because their role in saving equipment and also human lives. In this paper, we investigate and analyze the behavior of electric power systems under fault conditions and then evaluate various practical scenarios.

Placement of Fault Current Limiters in a Power System Through a Two-Stage Optimization Approach

With the sustainable growth in the number of new power plants and scale of transmission systems, the probability of the current exceeding the short-circuit rating of circuit breakers increases. A fault current limiter (FCL), which can be used to reduce current surges, has attracted considerable attention from utilities. However, the appropriate placement of FCLs in a power system for obtaining the most effective cost-to-benefit solution is crucial. This paper proposes a two-stage placement approach, where Stage I combines the hierarchical fuzzy logic decision (HFLD) method and Hashing-integrated generic algorithm (HIGA). The HFLD method is used for sorting feasible solutions, and the HIGA determines an optimal FCL placement in the reduced search space. Particle swarm optimization is then employed in Stage II for optimizing the FCL parameters. To verify the effectiveness of the proposed approach in solving the optimal FCL placement problem, the method is verified using the IEEE 30-bus system and system of a manufacturing factory in Taiwan. The numerical results show that the proposed method achieves a favorable solution in a short time with fewer placements of FCLs.

Power Analysis for a Limited Bus Grid System with Distribution Generators

It has been recognized recently that when injecting renewable energy source power to a load buses which connected to some distributed feeders in a power grid system, a stability problem occurs particularly when having high fault duties that exceeding the circuit breaker ratings at some substations. In this paper an analysis of power flow, short circuit, stability and protection are given in detail to an example of limited 7-bus power grid system. Comparison are illustrated between power grid with and without distributed generators regarding bus voltages, fault currents, critical power angles, selected current transformers and over current relay settings in each bus. It discusses the selection of optimum slack bus in Gauss Seidel method, and shows that the system with distributed generators is more stable although the fault currents are higher than the system without distributed generators.

Effect of Distribution Generators on Stability in a Limited Bus Power Grid System

It has been recognized recently that when injecting renewable energy source power to a load bus which connected to a distributed feeder in a power grid system, a stability problem occurs particularly when having high fault duties that exceeding the circuit breaker ratings at some substations. In this paper an analysis of power flow, short circuit, stability and protection is given in detail to an example of limited 7-bus power grid system. Comparison is illustrated between power grid with and without distributed generators regarding bus voltages, fault currents, critical power angles, selected current transformers and over current relay settings in each bus.

Comparison of Peak Armature and Field Winding Currents for Different Topologies of 10-MW Superconducting Generators Under Short-Circuit Conditions

This paper studies the peak armature and peak field winding currents for three different topologies of 10 MW partial high temperature superconducting generators (HTSGs) under short-circuit conditions (SCC) by simulation. The investigated partial HTSGs employ copper armature windings and superconducting field windings with different armature and rotor topologies, i.e., iron-cored armature and rotor, air-cored armature and rotor, and iron-cored armature and air-cored rotor. For each HTSG topology, the investigation includes: 1) the field winding current control strategies; 2) the influence of operating field current; and 3) the ratings of circuit breakers for limiting the peak armature and peak field winding currents. The results can provide guidelines for determining the peak armature and peak field currents of HTSGs and also the possibility of limiting them by employing circuit breakers under SCC.

Operation of a Medium Voltage Distribution Network with a Large Penetration of Distributed Generation

The paper presents the study of the behaviour of a real MV public distribution network in a mid-size in Italy, characterized by a very large amount of distributed generation (DG), reaching 100% of supplied network load. A parametric steady-state analysis of operating regimes was carried out, considering different load and DG scenarios (maximum and minimum load, maximum and minimum DG). The deterministic study did not evidence any operational problem, such as overloads and violation of voltage constraints. Occasional voltage violations (high MV voltages at full DG output) are easily overcome by tap-changer operation on the HV/MV transformers. Although feeder voltage profiles are actually improved by DG, a drastic power factor reduction is found at the utility supply points, as well as the possible active power flow inversion, entailing contractual and regulatory issues. Extensive short-circuit studies were also carried out, showing that DG fault contribution in the studied network is far from negligible, but does not dictate changes of either circuit breaker rating or overcurrent relaying coordination.

Optimal planning of series resistor to control time constant of test circuit for high-voltage AC circuit-breakers

AbstractThe equivalent test circuit that can deliver both short-circuit current and recovery voltage is used to verify the performance of high-voltage circuit breakers. Most of the parameters in this circuit can be obtained by using a simple calculation or a simulation program. The ratings of the circuit breaker include rated short-circuit breaking current, rated short-circuit making current, rated operating sequence of the circuit breaker and rated short-time current. Among these ratings, the short-circuit making capacity of the circuit breaker is expressed in peak value and not in RMS value similar to breaking capacity. A series resistor or super-excitation is used to control the peak value of the short-circuit current in the equivalent test circuit. When using a series resistor, a higher rating of circuit breakers leads to a higher thermal capacity, thereby requiring additional space. Therefore, an effective, optimal design of the series resistor is essential. This paper proposes a method for reducing ...

Symmetrical, Total, and Peak-Oh My: Is Current All I Use to Select My Circuit Breaker?

American National Standards Institute (ANSI)/IEEE medium-voltage circuit breaker ratings have changed in recent years, causing a great deal of confusion over how to properly select a breaker for short circuit duty. This article reviews the basics of an asymmetrical short circuit current waveform. It illustrates the effect of the X/R ratio and how the relationship between the dc component and the circuit-breaker contact parting time determines the interrupting time of the short circuit current. Five examples are discussed, and the first set examines basic power distribution system applications that illustrate the potential issues of mixing older megavolt- ampere (MVA)-rated switchgear with new circuit breakers rated using the voltage range factor K =1. The second set examines the complexities that occur when a generator with significant X/R ratio is directly supplying distribution switchgear. The examination of these different conditions is intended to aid equipment users in specifying the correct circuit breaker by identifying the critical factors and conditions affecting the performance of the circuit breaker.

Placement of Fault Current Limiters in Power System through a Two-stage Optimization Approach

With the sustainable growth in the number of new power plants and scale of transmission systems, the probability of the current exceeding the short-circuit rating of circuit breakers increases. A fault current limiter (FCL), which can be used to reduce current surges, has attracted considerable attention from utilities. However, the appropriate placement of FCLs in a power system for obtaining the most effective cost-to-benefit solution is crucial. This paper proposes a two-stage placement approach, where Stage I combines the hierarchical fuzzy logic decision (HFLD) method and Hashing-integrated generic algorithm (HIGA). The HFLD method is used for sorting feasible solutions, and the HIGA determines an optimal FCL placement in the reduced search space. Particle swarm optimization is then employed in Stage II for optimizing the FCL parameters. To verify the effectiveness of the proposed approach in solving the optimal FCL placement problem, the method is verified using the IEEE 30-bus system and system of a manufacturing factory in Taiwan. The numerical results show that the proposed method achieves a favorable solution in a short time with fewer placements of FCLs.

Electrical Stress Analysis of Switching Transients in 115 kV High Voltage Substation

This paper presents electrical stress analysis from capacitor bank switching in a 115 kV substation. The actual data of all equipment in substation are used in the simulated circuit by using ATP/EMTP program. The cases study focused on the determination of proper value of series reactor, effect of circuit breaker pole discrepancy on inrush current, line model selection and load variation. Electrical stress from energizing inrush current as well as transient recovery voltage and rate of rise of recovery voltage imposed on power circuit breaker during capacitor bank has been analyzed. The obtained results are used as guidelines for analysis of the electric stresses on substation equipment while capacitor banks are energized. Moreover, those results can be used to select the proper rating of circuit breakers to withstand the electric stresses in the transmission network.

Topology assessment for 3 + 3 terminal offshore DC grid considering DC fault management

This study assesses four DC grid topologies where each of the terminals can exchange power with any other terminal and a DC fault on any DC cable can be isolated. The DC grids are built using the following components: hybrid DC circuit breakers (CB), mechanical DC CBs, DC/DC converters and DC hubs. The aim is to compare DC fault performance, technical feasibility/readiness, power transfer security, expansion and costs. The base case for comparison are three separate 300 km offshore HVDCs connecting 3 1 GW offshore wind farms with three onshore VSC terminals. The rating of DC CBs is limited by the state of technology and costs which introduces limitation on the length of DC cables (because of communication delays) and on the DC bus fault level (limiting the number of connecting DC lines). DC/DC converters inherently block propagation of DC faults and their rating is not sensitive to DC fault level. DC hubs have considerable cost advantages over multiple DC/DC converters in cases where multiple DC systems are connecting at the same DC station. The cost assumptions for all major components are analysed, including the offshore platform costs. The study concludes that overall DC grid costs are similar (within 8%) for all four topologies. Although power security is similar for all technologies, the expansion options are best with DC/DC converters or DC hubs. DC hubs nevertheless suffer from highest on-state losses.

Design Guidelines for Safer Low-Voltage Distribution Systems Part II: Motor Circuits

This paper continues investigations of the concept of maximum low-voltage circuit breaker ratings that facilitate fast tripping for arcing faults with a selectively coordinated system. Motor loads are the focal point of this work. Guidelines are provided for maximum motor horsepower ratings that should be used depending on the kilovoltampere rating of the supply-side transformer. Using the guidelines should prevent a situation from occurring where the coordinated main circuit breaker short time and instantaneous settings are not sensitive enough to detect main bus arcing currents, and dangerous levels of arc incident energy are possible.

Short Circuit Fault Analysis of Electrical Power System using MATLAB

The objective of the present study is to simulate short circuit faults on different buses of a power system network and to estimate the state of the power system before and after a fault, which includes various bus voltages and current flow on various transmission lines. The analysis before the fault is carried out by solving non-linear load flow problem by using numerical iterative technique of Newton-Raphson method. State estimation after short circuit fault is carried by using algorithm of short circuit current computation. The short circuit currents dictate the rating of circuit breakers to be employed at various buses and in various lines of the network. The effect of three phase short circuit faults on power system has been studied in terms of post-fault conditions and pre-fault conditions. In this paper, three phase short circuit fault is simulated on the standard IEEE 11bus and IEEE 30 bus system and fault current level is calculated and short circuit MVA rating for the circuit breaker has been chosen. The analysis of power system under faulty conditions is important to determine the values of system voltages and currents during faulted conditions, so that protective devices may be set to minimize the harmful effects of such contingencies.