kV Double-circuit Transmission Line Research Articles

Distantaizsardzības Jutības Palielināšanas Metodes 330 kV Divķēžu Pārvades Elektrolīnijām

Distantaizsardzības Jutības Palielināšanas Metodes 330 kV Divķēžu Pārvades Elektrolīnijām

A neural network based protection technique for combined 275 kV/400 kV double circuit transmission lines

The work described in this paper addresses the problems encountered by conventional distance relays when protecting double-circuit transmission lines comprising different voltage levels. The problems arise principally as a result of the mutual coupling between the two circuits under different fault conditions; this mutual coupling is highly nonlinear in nature. An adaptive protection scheme is proposed for such lines based on employing a neural network (NN). A NN has the ability to classify the nonlinear relationship between measured signals and the faulted zone by identifying different patterns of the associated voltages and currents. One of the key points of this paper is data preprocessing of the measured signals essentially to extract the most significant features from the signals. The adaptive protection scheme is tested under a specific fault type, but varying fault location, fault resistance, fault inception angle and different source capacities. All the test results clearly show that the proposed adaptive protection technique is well suited for double circuits with different voltage levels.

Protecting NYSEG's six-phase transmission line

The high phase order transmission demonstration project is described. An existing 115 kV double-circuit transmission line was electrically reconfigured into a single-circuit, six-phase transmission line for this purpose. A description is given for different computer applications used in all stages of design, operation, and postoperation analysis. The complex multirelay microprocessor-based protection system is discussed. The multirelay microprocessor protection system was tested for many typical fault combinations using a computer controlled fault simulator. Currents and voltages were calculated using the Electromagnetic Transient Program (EMTP).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Stability evaluation of a power network in connection with a unit regulating exciter based on system frequency characteristics

This paper presents a mathematical model (algorithm) suitable for calculating the transfer function of a practical power network. For this network the steady-slate stability limits are derived and the non-linear characteristics of the transfer function are considered. The computational results obtained by using the proposed model differ from the corresponding ones obtained previously by approximate methods, whereas they are in close agreement with similar results obtained from experimental measurements. The oscillation coefficients of first- and second-order derivatives of the generator current highly characterize the performance of the locus diagram of the generator transfer function. The proposed accurate technique is applied to a part of the Egyptian power system consisting of a power station, a substation and a 500 kV double circuit transmission line.

Electromagnetic fields in the near vicinity of transmission line towers

Electromagnetic fields in close proximity to transmission line towers are calculated using moment method procedures. The method of moments is especially suited to problems which involve electromagnetic coupling to metal objects and, in principle, most any type geometry can be solved. Generally, this technique involves the solution of an integral equation for the current and charge induced on the object by an external field. Metal transmission line towers are modeled as a collection of straight cylindrical sections of varying radii. Because the wavelength of a 60 Hz field is much larger than the cross sectional area of the segments, the problem can be categorized as "scattering by thin wires". The current and charge distributions induced on a 230/138 kV double circuit transmission line tower are calculated. Utilization is made of the induced current and charge for the purpose of determining the fields near the towers. Comparison is also made between calculated and measured near fields.