Electrostatically Induced Voltages and Currents on Conducting Objects under EHV Transmission Lines

This paper gives the results to date of radio influence and corona loss tests performed at a voltage of 775 kV at the extra-high-voltage test project at Apple Grove, W. Va., a joint research project sponsored by the American Electric Power Service Corporation and Westinghouse Electric Corporation with six other participating companies. Effects of line radio-influence terminations and larger centerphase conductors are discussed. Radio influence and corona loss results are given for there test lines utilizing 4-conductor bundles with subconductor diameters of 1.0, 1.196, and 1.382 inches.

The Apple Grove 750-kV project, jointly sponsored by American Electric Power Service Corporation and Westinghouse Electric Corporation, with six other participating companies, was designed to provide data on corona loss and radio influence performance of conductors at a nominal voltage of 750 kV and to determine the technical and economic feasibility of transmitting power at this extra-high-voltage. The project also incorporates facilities for studying conductor configuration, insulator assemblies, spacers, connectors, splices, hardware, and steel structures. Operating experience has been gained on a 750-kV transformer, lightning arresters, coupling capacitors, and line traps, as well as on a typical 500-kV line design. This paper describes equipment design, instrumentation, and special project features, such as the determination of conductor performance on a statistical basis by the use of simultaneous comparison under the same environmental conditions.

TEQC is a tool which can be commonly used in GNSS data translation, editing, and quality checking, it's widely used in GNSS data preprocessing. This paper has introduced the common syntax and instruction of TEQC when it used in GNSS data processing, also introduced the testing examples of GNSS receiver under three environments: 220KV UHV transmission line environment, 500KV UHV transmission line environment and standard GNSS calibration field, then using TEQC to preprocess and analysis the data. The results showed that: a)The GNSS observation data Efficiency is not effected from radio interference generated by EHV transmission lines; b)Within 25 meters ranges GNSS observation data under EHV transmission line, the multi-path effects (mp1 and mp2 value) significantly exceeded the normal range, and the voltage higher, the multi-path value larger. c)Apart from 50 meters outside EHV transmission line, there is almost no effect about multi-path affects in the high-precision GNSS observation data.

At present, the EHV transmission system in China has entered a new stage of large-scale construction, which is different from the general EHV transmission lines. The distributed current in the EHV transmission lines has increased substantially. To realize the overall balance of long-distance transmission in the power grid, a differential protection method for EHV transmission lines based on current traveling wave prediction is proposed. The fault current traveling wave of the EHV transmission line is predicted. The fault current traveling wave section is distinguished, and different schemes are selected to realize the traveling wave differential protection for internal and external faults. The simulation results show that the proposed method is reliable and sensitive for the protection of UHV transmission lines, and has certain practical value for ensuring the stable operation of the smart grid.

American Electric Power (AEP) has selected its Inez Substation in eastern Kentucky for the location of the world's first Unified Power Flow Controller (UPFC) installation. Comprising two /spl plusmn/160 MVA voltage-sourced GTO-thyristor-based inverters, this installation is not only the first practical demonstration of the UPFC concept, but also by far the highest power GTO-based Flexible AC Transmission Systems (FACTS) equipment ever installed. The installation will be the first demonstration of this type of equipment connected in series with a transmission line. The project is a collaborative effort between AEP, the Westinghouse Electric Corporation, and the Electric Power Research Institute (EPRI), and has been divided into two phases corresponding to the installation of the shunt- and series-connected inverters respectively. Phase I (installation and commissioning of the shunt inverter (STATCOM)) was completed successfully in July, 1997, and the STATCOM is now operational. Phase II is scheduled for completion in early 1998. This paper gives a brief background to the project, describes the installation and special features of the equipment, and reports on the Phase I commissioning and STATCOM operation.

Lightning is main reason that endangers safety and reliability of transmission line, but existing models of estimating shielding failure flashover rate can not be in agreement with field experience at present. This paper deals with shielding failure flashover rate of EHV transmission lines with many parameters by improved electric-geometry model. The parameters consist of phase wires, shield wires, and ground angle. In improved model, strike is calculated with expression recommended by IEEE, the striking distance factor is introduced to describe difference of electric intensity between lightning stroke on transmission line and ground, and uncovered is adopted to calculate shielding failure flashover rate for ultra high voltage transmission line. Taking 500 kV transmission line as example, improved electric-geometry model gets result in agreement with field experience. Compared with order of method, it is more accurately. At same time, paper analyzes influence of shielding angle, height of wire, grounding obliquity on shielding failure flashover rate. The results of studies show that shielding failure flashover rate is a function of shielding angle, ground angle and height of tower. It will increase with increase of grounding obliquity, protection angle and height of tower. The simulation calculation shows that when shielding angle is -6.24 degrees, shielding failure flashover rate reduces from 0.2135 to 0 in this paper. It will help designers in making correct economic judgment.

Research Papers Variable Flow Resistance With Adjustable Multihole Orifice Plates in Series J. Sherman, J. Sherman PWR Core 2 Design, Bettis Atomic Power Division, Westinghouse Electric Corporation, Pittsburgh, Pa. Search for other works by this author on: This Site PubMed Google Scholar F. A. Grochowski, F. A. Grochowski PWR Core 2 Design, Bettis Atomic Power Division, Westinghouse Electric Corporation, Pittsburgh, Pa. Search for other works by this author on: This Site PubMed Google Scholar J. E. Sharbaugh J. E. Sharbaugh PWR Core 2 Design, Bettis Atomic Power Division, Westinghouse Electric Corporation, Pittsburgh, Pa. Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information J. Sherman PWR Core 2 Design, Bettis Atomic Power Division, Westinghouse Electric Corporation, Pittsburgh, Pa. F. A. Grochowski PWR Core 2 Design, Bettis Atomic Power Division, Westinghouse Electric Corporation, Pittsburgh, Pa. J. E. Sharbaugh PWR Core 2 Design, Bettis Atomic Power Division, Westinghouse Electric Corporation, Pittsburgh, Pa. J. Basic Eng. Sep 1960, 82(3): 645-653 (9 pages) https://doi.org/10.1115/1.3662688 Published Online: September 1, 1960 Article history Received: July 26, 1959 Online: November 4, 2011

Lightning stroke is the main cause of trip-outs of EHV and UHV transmission lines in China Southern Power Grid (CSG). In order to improving the lightning performance of overhead transmission lines, the lightning activities of CSG in 2006 to 2014 was analyzed. It indicates that the coastal Guangdong and Guangxi province are suffered more ground flashes, where the average ground flash density is over 7.98 flashes/km2/year. 306 lightning flashover incidents of 500kV AC, ± 500kV HVDC and ± 800kV UHVDC transmission lines were investigated. It is inferred that about 84% lightning flashover incidents was caused by lightning shielding failure. The corresponding ground wire protection angle for 81% incidents is larger than 5°, and with protection angle decreases, lightning trip-out failures are significantly reduced. Based on the guidelines proposed by IEEE and CIGRE working group, CSG has developed their own lightning risk estimation tool named LPTL. The predication result of six 500kV AC transmission lines was compared to field experience which validates the IEEE recommended method for 500kV AC transmission lines. Further works should be done to revisit the validity of existing risk estimation method for HVDC transmission lines.

Digital Current Differential Carrier Relaying System for EHV Transmission Line

As electricity demand increases day by day due to economic growth, the process of transmitting efficient electrical power is vital. Thus, a power simulation study is required to determine the mechanism of the transmission line, and possible faults that occurred in the transmission line system. On a daily basis, single line to ground fault (L-G), double line to ground fault (2L-G), and triple line to ground fault (3L-G) are the faults that normally occur in the long transmission line system. In this project, a model of a 300km/500 kV EHV transmission line consisting of a three-phase source, distribution line, and load is simulated using MATLAB software. When the L – G fault is applied, the voltage is diminished to zero and upon fault clearance, the R – G line produced overvoltage and overcurrent by 518.9 kV and 1889 A, which increased about 46.83% and 15.67% compared to normal lines of Y – G and B – G at 353. kV and 1633 A. Then, for the 2L – G fault, again the voltage is reduced to zero and when fault clearance occurred, the R – G and Y – G lines experienced overvoltage and overcurrent at 570.4 kV and 708.5kV, which showed more than 60% transient compared to normal line B-G at 353.4 kV. In Contrast, the 3L – G fault causes all transmission lines to experience overvoltage and overcurrent at different times and can damage the whole transmission system. Thus, to reduce the severe impact of fault, the Inverse Definite Minimum Time Over Current (IDMT O/C) relay protection is installed in the line model.

Transmission lines are an important part of a power system. Transmission lines have high power transmission capacity and they are prone to faults of larger magnitudes. Various faults occur in transmission lines. Therefore, protection relays are necessary to protect transmission lines. The purpose of protection system is to interrupt the faulty section from the healthy section because the fault currents may damage the electrical equipments. One of the protection relays is distance relay and it is mainly used in transmission line. Sometimes these relay are used for backup protection. Distance relays for determining the impedance need the voltage and current. Transmission lines are typically protected by distance protection relay. Distance relays are considered of high speed class and can provide transmission lines. Nowadays, numerical distance relays have been used instead of using electromechanical and static distance relays. The proposed model was verified under different tests such as single line to ground (L-G) fault, double line to ground (L-L-G) fault, line to line (L-L) fault and three phase (L-L-L) fault. SimPower System was used for modelling and simulation of distance relay, transmission lines and faults. The simulation results were obtained from MATLAB software shows the feasibility of analysis of transmission line protection with mho type distance relay for single line to ground fault, double line to ground fault, line to line fault and three phase fault at different location of transmission lines. The difficulties understanding on operation of distance relay can be cleared by using MATLAB/SIMULINK software.

Techno-economic feasibility of lighting protection of overhead transmission line with multi-chamber insulator arrestors

Most transmission line protective schemes are based on deterministic computations on a well defined model of the system to be protected. This results in difficulty because of the complexity of the system model, the lack of knowledge of its parameters, the great number of information to be processed, and the difficulty in taking into consideration any system variation as the rules are fixed. The application of fuzzy logic for exploring complex, nonlinear systems, diagnosis systems and other expert systems, particularly when there is no simple mathematical model to be performed, provides a very powerful and attractive solution to classification problems. In this paper, a feasibility study on the application of different fuzzy reasoning mechanisms to power system relaying algorithms is conducted. Those mechanisms are namely, Mamdani's mechanism, Larsen's mechanism, Takagi-Sugeno's mechanism, and Tsukamoto mechanism. A comparative analysis on the application of these fuzzy inference mechanisms to a novel fault detection and phase selection technique on EHV transmission lines is reported. The proposed scheme utilises only the phase angle between two line currents for the decision making part of the scheme. A sample three-phase power system was simulated using the EMTP software. An online wavelet-based preprocessor stage is used with data window of 10 samples (based on 4.5 kHz sampling rate and 50 Hz power frequency). The performance of the proposed model was extensively tested in each case of fuzzy inference mechanism using the MATLAB software. The advantages and disadvantages of each mechanism are reported and compared together. Some of the test results are included in this paper.

High impedance faults (HIFs) are difficult to be detected by overcurrent protection relays. This paper presents an ATP/EMTP fault simulations studies based algorithm for high impedance fault detection in extra high voltage transmission line. The scheme recognizes the distortion of the voltage waveforms caused by the arcs usually associated with HIF. The discrete wavelet transform (DWT) based analysis, yields three phase voltage in the high frequency range which are fed to a classifier for pattern recognition. The classifier is based on an algorithm that uses recursive method to sum the absolute values of the high frequency signal generated over one cycle and shifting one sample. A HIF model of distribution is modified for EHV transmission lines. Characteristics of the proposed fault detection scheme are analyzed by extensive simulation studies that clearly reveal that the proposed method can accurately detect HIFs in the EHV transmission lines.

The accurately mathematical models, simulation models and protection algorithms of high impedance fault (HIF) on transmission lines are difficult problems. Based on the measured data and physical phenomena, a new mathematical model of HIF was presented by numerical analysis methods and MAYR’s equation. Using EMTP, the model of HIF includes a group of nonlinear time-varying resistances and a dynamic arc resistance. Based on the features of HIF under different frequency bands, this paper presents HIF comprehensive detection algorithms containing four algorithms, and analyzes the logic between each algorithm. Finally, the models and algorithms are simulated.