Power Transmission by Direct Current

ISBN-13: 9783642660740 / Angielski / Miękka / 2011 / 390 str.

E. Uhlmann

Opis

The direct current transmission scheme linking the island of Gotland to the main land of Sweden by means of a submarine cable under the Baltic Sea is the first commercial realisation of a modern technique for the transmission of electrical energy. It is certainly not accidental that this pioneering initiative was allotted to the Gotland scheme. Various viewpoints may be presented regarding this, but the essential factor relates to the circumstances that permitted the magnitude ofthe transmitted power to be given a value which would not have been technically or economically feasible for any other project. The power, on the one hand, was sufficiently small to justify the risk associated with such a new venture, for it fell within limits acceptable both to ASEA as the manufacturer and to the Swedish State Power Board as the customer. On the other hand, the power was large enough to demonstrate the technical and economic characteristics of the new system and to provide the opportunity of gaining invaluable experience that could be applied to future large-scale transmission systems. In 1954 a team under the direction of Dr. Uno Lamm successfully commissioned the Gotland scheme, representing the culmination of many years of intensive development work."

Spis treści

1. Introduction.- A. Theory of Converters and Transmission Systems.- I. Converters without Reactance on the Alternating Current Side.- 2. Converter Circuits.- 3. Voltage and Current Wave Forms.- 3.1 Direct Voltage Wave Form.- 3.2 Valve Voltage Wave Form.- 3.3 Network Current Wave Form.- 4. Converter Performance under Special Conditions.- 4.1 Network Current Asymmetry.- 4.2 Direct Current Harmonics.- 4.3 Network Voltage Asymmetry.- 4.4 Amplitude Rectification.- 4.5 Direct Current Wave Form.- 4.6 Energisation and De-energisation of Valve Bridges.- 4.7 Abnormal Valve Bridge Behaviour.- 4.8 Special Control Methods.- II. Converters with Reactance on the Alternating Current Side.- 5. Commutation Process.- 5.1 Overlap Angle.- 5.2 Direct Voltage Drop.- 5.3 Power and Reactive Power.- 5.4 Harmonics.- 5.5 Transient Processes due to Commutation.- 6. Characteristics.- 6.1 Rectifier Bridge Characteristics.- 6.2 Inverter Bridge Characteristics.- 6.3 12-pulse Converter Characteristics.- 6.4 Effect of Network Reactances.- 7. Overcurrents.- 7.1 Short-Circuit Current of the Rectifier.- 7.2 Arc-Back Currents.- 7.3 Short-Circuit Currents in Inverters.- 8. Converter Performance under Special Conditions.- 8.1 Asymmetrical Network Voltages.- 8.2 Forced Commutation.- III. Direct Current Transmission Links.- 9. Basic Aspects of Direct Current Transmission.- 10. Control of the Direct Current Transmission Link.- 10.1 Current Control.- 10.2 Higher-Level Control System.- 10.3 Stabilisation of Alternating Current Networks.- 11. Multi-Terminal Transmission Links.- 11.1 Connection Arrangements.- 11.2 Breakers in Direct Current Networks.- 12. Models.- B. Elements of the Direct Current Transmission Link.- IV. Direct Current Side.- 13. Overhead Lines.- 13.1 Transmission Line Systems.- 13.2 Dimensioning of Overhead Transmission Lines.- 13.3 Corona Effects.- 13.4 Transmission Line Insulation.- 13.5 Ground Faults on Direct Current Transmission Lines.- 13.6 Harmonics on Direct Current Lines.- 13.7 Line-End Protection.- 14. Direct Current Cables.- 14.1 Dimensioning of Direct Current Cables.- 14.2 Leakage Currents.- 14.3 Overvoltages on Cables.- 15. Ground Return.- 15.1 Current Distribution in the Ground.- 15.2 Ground Electrodes.- 15.3 Sea Electrodes.- 15.4 Advantages and Disadvantages of Ground Return.- 15.5 Electrode Connection to the Converter Station.- 16. Apparatus on the Direct Current Side.- 16.1 Capacitors.- 16.2 Arresters.- 16.3 Direct Current Circuit-Breakers.- V. Converter Stations.- 17. Valves.- 17.1 Mercury-Arc Valves.- 17.2 Thyristor Valves.- 18. Converter Transformers and Direct Current Reactors.- 18.1 Converter Transformers.- 18.2 Direct Current Reactors.- 19. Auxiliary Equipment and Circuits.- 20. Insulation Coordination.- 21. Layout of the Converter Station.- VI. Elements of the Alternating Current Network.- 22. Electrical Machines.- 22.1 Harmonic Load.- 22.2 Speed Control.- 22.3 Rectifier Connection to Power Stations.- 23. Alternating Current Filters.- 23.1 Harmonic Impedance of the Alternating Current Network.- 23.2 Filter Dimensioning.- 23.3 Protection of Filter Elements.- 24. Switching in Alternating Current Networks.- Literature.