Six-phase Transmission Research Articles

Six-phase (multiphase) power transmission systems: A generalized investigation of the load flow problem

This paper deals with the generalized investigation of load flow problems of six-phase (multiphase) power transmission systems and presents several schemes for power flow calculations covering balanced and unbalanced network situations. Initially, the system models and algorithm for the assembly of the multi-phase bus admittance matrix are described. Equivalent single- and three-phase load flow studies are carried out employing the equivalent single- and three-phase representations of a six-phase transmission system. The procedure for phase coordinate load flow retaining the physical identities of the three-phase and six-phase elements is developed to investigate the problem of unbalances existing both in a three-phase and a six-phase portion of a composite power transmission network. The problem of obtaining effective starting solutions is also investigated and the computational requirements for various cases are quantified. The procedures developed in the paper are implemented on a sample system. Finally, the paper concludes with a discussion of the major findings and a future line of investigation.

EPPC - A Computer Program for Six-Phase Transmission Line Design

EPPC - A Computer Program for Six-Phase Transmission Line Design

EPPC - A Computer Program for Six-Phase Transmission Line Design

Allegheny Power System (APS) conducted a three-year study during 1976-79 on the feasibility of converting some of their 138-kV three-phase double- circuit lines to 138-kV six-phase lines. The analytical development of this novel study has been documented in the form of a generalized computer program entitled "Electrical Parameters and Performance Characteristics" (EPPC). This software is a valuable tool for the design of a six-phase transmission line.

Steady-state modelling of six-phase (multiphase) transmission systems

The modelling aspects of a 6-phase (multiphase) power transmission system, which have not previously been fully explored in the literature, are discussed. Initially, representations of various components, namely 3-phase/6-phase transformers, 6-phase transmission lines, machines and loads, are developed. A multiphase (or composire 3-phase and 6-phase) power system is then modelled: in balanced conditions on a single-phase basis, in unbalanced conditions as an equivalent 3-phase system; and also as a composite 3-phase and 6-phase system retaining the physical identities of the different elements. The procedure is explained with the help of a numerical example.

Fault analysis of six-phase systems

This paper presents an overview of the feasibility of six-phase transmission, symmetrical and Clarke's component transformations for six-phase systems derived from firm group theoretic considerations, and an analysis of the various faults likely to occur on six-phase systems. A numerical example is given to compare the magnitudes of fault currents involved for a six-phase and a double-circuit three-phase system for the most severe and most common cases. Finally, the future scope of the present investigations is indicated.

Six-phase (multi-phase) power transmission systems: Fault analysis

The motivation for writing this paper stems from the question, If the concept of six- (multi-) phase systems become feasible, how to plan such systems? One of the important aspects of transmission planning is the design of adequate protective scheme which requires a detailed fault analysis. It is well-known that the theory of symmetrical components is an important tool for such analysis. The first part of the paper is devoted to the development of the symmetrical component theory for six-phase systems. The remaining part of the paper deals with both symmetrical and unsymmetrical fault analysis of six-phase transmission systems. The results of the paper could readily be used by power system planners.

The possibilities of transmission by underground cables at 100,000/150,000 volts

The paper is primarily a plea for the use of single-phase cables. The effect of separating the cores is considered, both in its relation to easing the potential gradient and in relation to eddy currents induced in the lead sheathing. The gain effected by employing ?intersheaths? is pointed out, and the author's proposals for obviating the disadvantages of intersheaths by combining their employment with a six-phase transmission are considered. An actual transmission of 50,000 kW at 100,000 volts over a distance of 30 miles is worked out in detail and compared with a similar transmission at 30,000 volts. A saving of roughly £500,000 is shown. The principal conclusions arrived at are:? (1) Reliability under the six-phase/three-phase system very greatly increased, as compared with plain single-core cables (as at Gennevilliers), or with three-phase cables for equal-voltage. (2) The author's arrangements will permit of loads of poor power factor being taken up, with positive gain in efficiency and regulation. (3) The maximum voltage gradient being no greater with 100,000 volts than with 30,000 volts, such transmissions can be undertaken immediately the cable makers are in a position to guarantee the cables. (4) The investment in capital outlay proceeds, in the six-phase/three-phase scheme, in proportion to the development of the load. A start could thus be made with only 8,000 kW. (5) The reduction in line-charging current in the six-phase/three-phase scheme, and the improvement in ?regulation? are very considerable, as compared with those for any other proposals.