Neutral Grounding Reactor Research Articles

A Novel Method to Improve the Residual Life of Switchgear by Reducing the Impact Caused by Thermal and Mechanical Stresses Produced Due to SLG Cable Faults in Electrical Substations

From the studies carried out in the field of power systems, it is found that the single line to ground fault is more common and produces severe electro-mechanical and thermal stress on the connected equipment. In urban areas, power utilities are replacing the overhead conductors with underground cables due to low availability of space for new lines or ROW issues. With the increase in the number of power cables, it is becoming difficult for the utilities to maintain and test the healthiness of the cables. On the other side, due to advances in computational capabilities, the manufacturers are providing an optimized solution which is reducing the fault feeding capability of the equipment and equipment are failed frequently. In this paper, a new advanced method of protecting the power transformers from SLG faults using both conventional and automated techniques is proposed. A combined solution using conventional and automation provides a redundant and robust approach to improve the residual life of equipment. To limit the fault current due to SLG faults neutral grounding reactor (NGR) is proposed, and GOOSE technique is used to isolate the equipment from the fault as soon as possible. The proposed method is simulated using MATLAB/SIMULINK and results obtained are satisfactory.

An Innovative Shielding Strategy for Stray Loss Reduction of Neutral Grounding Reactor

Leakage fluxes formed by power equipment are one of the serious concerns of the electricity industry. Stray losses, which are a consequence of leakage fluxes, can lead to thermal stresses in metallic parts and dramatically reduce the life of the equipment. To alleviate this obstacle, this article aims to deploy a new approach to mitigate the stray losses in structural parts. This method is based on electric and magnetic shielding to deviate or bypass the stray fluxes and abstain from hot spots. Computation of stray losses inside the shields and other metallic structures is conducted using 3-D finite element analysis (FEA). To determine the dimensions of shields, various contingency simulations are implemented. A 0.51 MVAr, air-core, oil-immersed neutral grounding reactor (NGR) is considered as a case study to verify the effectiveness of the presented method. The performance of the suggested shield arrangement has been experimentally investigated, and the obtained results present an indication of a best-suited design with respect to performance and size.

A Continuous Monitoring for Neutral Grounding Resistors and Reactors With Hardware Validation

Neutral grounding devices (NGDs) are used to limit ground overcurrents, control transient overvoltages, and overcome the consequent issues. Intactness of these apparatuses is vital to prevent the risk of ungrounded or solidly grounded neutral. As such, they should be continuously monitored as targeted here. This paper proposes a continuous monitoring technique that supervises the NGD impedance obtained via full-range voltage and current measurement. It benefits from a new and cost-effective voltage metering mechanism specifically designed for the studied problem. Its performance has been validated using a fabricated prototype. In contrast to existing methods, the application of the proposed technique is not limited to a specific configuration, system operation mode, or NGD. Furthermore, monitoring is performed without signal injection. This monitoring technique shows reliable operation under various conditions of the system and grounding apparatuses based on the analysis performed using PSCAD in conjunction with MATLAB.

Electromagnetic Transient Analysis of 750kV Four-circuit Transmission Line on the Same Tower

The ATP-EMTP program is used to calculate the power frequency overvoltage, open-phase power frequency resonant overvoltage, induced voltage and current, secondary arc current and recovery voltage, and switching overvoltage of 750kV four-circuit transmission line on the same tower. The study reveals that the configuration of four circuits on the same tower has little influence on the power frequency and switching overvoltage, but greatly influences the secondary arc current and recovery voltage, and induced voltage and current. Therefore, measures like installing high-voltage shunt reactor and neutral grounding reactor and line transposition are required. Also, the induced voltage and current ratings of earthing switch are proposed.

Parameter Estimation of Neutral Grounding Reactor for a Single Line to Ground Fault for Transformer

Parameter Estimation of Neutral Grounding Reactor for a Single Line to Ground Fault for Transformer

Selection of Neutral Grounding Reactor for Line to Ground Fault

Selection of Neutral Grounding Reactor for Line to Ground Fault

Design and Analysis of a kA-Class Superconducting Reactor

Abstract —This paper presents the designs of kiloampere-classreactors with high temperature superconducting (HTS) BSCCOtapes. The HTS solenoidal windings of the 100 A-class andkiloampere-class reactors consist of 34 coil layers and 136 coilturns in total. The structural design and performance evaluations,including critical current and ac loss calculations are discussedfor a single-phase grounding fault case and compared with a con-ventional copper reactor. The method to apply the HTS tapes andthe principal features of the HTS reactors have been theoreticallyidentified. Index Terms — AC loss, BSCCO, current limiting reactor, neu-tral grounding reactor, superconducting reactor. I. I NTRODUCTION R EACTORS ARE widely used in modern power systems,which provide functions such as limiting currents, com-pensation of power, and inductive connection to ground. Powerquality and reliability problems are normally caused by theabnormal operations of large-scale equipments and the short-circuit faults caused by the power system itself. High tempera-ture superconductors (HTSs) have been successfully applied inthe advanced reactor developments. As an example, a numberofreactor-basedsuperconductingfaultcurrentlimiters(SFCLs)including the saturated iron-core type [1], [2], transformer type[3], [4] reactor type [5], [6], and non-inductive type [7] aremadeavailabletoreducethefaultcurrentlevelsontransmissionand distribution networks.The power system faults mainly include three-phase shortcircuit, two-phase short circuit, two-phase grounding short cir-cuit and single-phase grounding short circuit. The single-phasegrounding faults, for example, account for about 91.23% of thetotal number of power system faults in the 6434 power trans-mission lines of 220 kV Chinese power grid in 2008. It meansthat single-phase grounding faults need to be solved urgently toimprove the whole power system quality and reliability [8].In the neutral indirectly grounded power systems, the single-phase grounding fault occurs most frequently. The three-phaseline voltages still keep symmetrical states and have negligibleimpact to the local power equipments. Therefore, the powersystem is allowed to continue running up to few hours before

Optimal Design Specifications of 22.9 kV HTS-FCL Applied in Real Korean Power System

KEPCO decided to apply the HTS FCL and cable in real substation in 2009. This is the first commercial demonstration case and starting point of the HTS equipment in South Korea, even though this is not a general perfect commercialization. For a successful application on this commercialization preliminary, it is quite important to design the HTS-FCL specification with regard to the current status of the application site (for example, the existence of NGR (Neutral Grounding Reactor), 3-winding low% impedance and so on). This paper evaluates the necessary and sufficient design specifications of the 22.9 kV HTS-FCL to fulfill the real power system conditions. It investigates the detailed design criteria, short circuit capacity, FCL impedance, protection scheme, fault limiting type and other design parameters to learn the real status of ICHEON substation which will be using the HTS- FCL.

Standardization or Ratings of Neutral Grounding Reactors

Standardization or Ratings of Neutral Grounding Reactors

Temperature Limits for Short-Time Overloads for Oil-insulated Neutral Grounding Reactors and Transformers - II

Temperature Limits for Short-Time Overloads for Oil-insulated Neutral Grounding Reactors and Transformers - II

Temperature limits for short-time overloads for oil-insulated neutral grounding reactors and transformers-II

In part I, published in 1938,1 the principal question considered was the effect of ventilating coils on temperature limits for ground faults greater than one minute, for which it was assumed that 160 degrees centigrade based on all heat stored in copper was the correct limit. Since 1938 considerable new data have been obtained. This paper presents the new data and shows that: 1. For heating periods of one minute or less, practically all aging of insulation occurs during the cooling period. It is shown that temperature limits can be based on the rate of cooling rather than on the heating period. 2. In the heating-up period of one minute or less, 25 to 45 per cent of the loss is dissipated from the copper to the insulation and oil. Formulas are developed for calculating the temperatures during the heating and cooling periods. 3. Temperature limits above 160 degrees centigrade for one minute are permissible for both non-ventilated and ventilated coils, being approximately 200 degrees centigrade for windings which cool sufficiently rapidly.

Temperature limits for short-time overloads for oil-insulated neutral grounding reactors and transformers — II

In part I, published in 1938, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> the principal question considered was the effect of ventilating coils on temperature limits for ground faults greater than one minute, for which it was assumed that 160 degrees centigrade based on all heat stored in copper was the correct limit.

Temperature limits for short-time overloads for oil-insulated neutral grounding reactors and transformers — II

Temperature limits for short-time overloads for oil-insulated neutral grounding reactors and transformers — II

Temperature limits for short-time overloads for oil-insulated neutral grounding reactors and transformers

Discussion and author's closure of a paper by V. M. Montsinger published on pages 39–44 of this volume (January section), and presented for oral discussion at the relays and reactors session of the winter convention, New York, N. Y., January 25, 1938.

Temperature limits for short-time overloads for oil-insulated neutral grounding reactors and transformers

THE PROTECTIVE DEVICE committee is working on the problem of preparing standards for neutral grounding devices. One of the most important points up for consideration is the selection of the temperature limits for various times of operations of the devices.

Temperature Limits for Short-Time Overloads for Oil-Insulated Neutral Grounding Reactors and Transformers

In part I, published in 1938,1 the principal question considered was the effect of ventilating coils on temperature limits for ground faults greater than one minute, for which it was assumed that 160 degrees centigrade based on all heat stored in copper was the correct limit. Since 1938 considerable new data have been obtained. This paper presents the new data and shows that: 1. For heating periods of one minute or less, practically all aging of insulation occurs during the cooling period. It is shown that temperature limits can be based on the rate of cooling rather than on the heating period. 2. In the heating-up period of one minute or less, 25 to 45 per cent of the loss is dissipated from the copper to the insulation and oil. Formulas are developed for calculating the temperatures during the heating and cooling periods. 3. Temperature limits above 160 degrees centigrade for one minute are permissible for both non-ventilated and ventilated coils, being approximately 200 degrees centigrade for windings which cool sufficiently rapidly.

General considerations in grounding the neutral of power systems: The neutral grounding reactor: Operating performance of a Petersen earth coil: Present day practise in grounding transmission systems: Systems transmitting at generated voltage: Systems transmitting at higher than generated voltage

R. W. Atkinson: I want to say a word with regard to the comparison between the condition of a cable system and an overhead open-wire system with regard to the grounding of the neutral. There is a large and important difference for two reasons. The most important reason is the relative cost of insulation of the cable system as compared with the overhead cable for high voltage. The insulation is a very important part of the transmission system, whereas it is a relatively minor part in the overhead system. You can afford in the overhead system to put on insulation to take care of the voltage rise due to abnormal conditions, and you can afford to put on the insulation to take care of service conditions; whereas the same difference in service conditions costs you a whole lot more in insulation of cable systems. Another difference from the standpoint of operation, is the very much greater electrostatic capacity for the cable system.

The neutral grounding reactor

A neutral grounding reactor (Petersen Coil) has been in operation on the system of the Alabama Power Company since October 12, 1921. This is the first of these devices in this country, although there are perhaps several hundred of them in operation in Europe. The present paper discusses the tests made shortly after installation of this reactor. A companion paper by Messrs. J. M. Oliver and W. W. Eberhardt, discusses the operation of the reactor for a period of about a year. It is believed that this device has a somewhat limited use in this country on account of the prevalence and popularity of the solidly grounded neutral. Nevertheless, there are certain installations favorable to the use of the reactor and it is partly the purpose of the present paper to outline the field of this device as well as to show how its rating may be determined for a particular system.

The Neutral Grounding Reactor

A neutral grounding reactor (Petersen Coil) has been in operation on the system of the Alabama Power Company since October 12, 1921. This is the first of these devices in this country, although there are perhaps several hundred of them in operation in Europe. The present paper discusses the tests made shortly after installation of this reactor. A companion paper by Messrs. J. M. Oliver and W. W. Eberhardt, discusses the operation of the reactor for a period of about a year. It is believed that this device has a somewhat limited use in this country on account of the prevalence and popularity of the solidly grounded neutral. Nevertheless, there are certain installations favorable to the use of the reactor and it is partly the purpose of the present paper to outline the field of this device as well as to show how its rating may be determined for a particular system.