International Conference on Large High Voltage Electric Systems II. (töredék) [antikvár]

31-01 LONG DISTANCE AC TRANSMISSION USING STATIC VOLTAGE STABILISERS AND SWITCHED LINEAR REACTORS O by J.D. AINSWORTH, C.B. COOPER, E. FRIEDLANDER H.L. THANAWALA GEC Switchgear Ltd., Power Transmission Division, Stafford (United Kingdom) SUMMARY With increasing lengths of a.c. transmission lines the limitations due to static and transient stability may require a reduction in the power per circuit, at a given voltage. For long lines shunt reactors are necessary to prevent dangerous overvoltages. The power limit can be extended by the use of series capacitors, but there is a limit to the amount of series compensation which is practicable. This leads to an increasing demand for higher voltages or a larger number of parallel circuits ; both of these are of course expensive. A scheme based on static voltage stabilisers containing saturated reactors which effectively divide the line into several shorter stable sections avoids the disadvantages of the linear system but can be expensive, if at light load the saturated reactors have to absorb nearly all the capacitive power of the line. This led to the consideration of a hybrid shunt stabilised scheme, in which the saturated reactors are assisted at light load by shunt linear reactors ; the justification of this and of other improvements on technical as well as economical grounds is the subject of this paper. High voltage, Long lines. Power transmission. Reactive power. Saturated reactor. Stabiliser, Static stabiliser. Swing damping. Voltage stabiliser. REPORT 1. INTRODUCTION This paper is concerned with the method of long distance a.c. power transmission in which the voltage is under normal conditions held constant at several points along a line by means of shunt stabilisers of the static saturated reactor type having an inherently almost instantaneous response. The main advantages of the method have been mentioned in earlier publications, [quoted in ref. 1 ], but it has not so far been used in long distance transmission because up to now series capacitor compensation has been economically more attractive in spite of its technical limitations. The paper demonstrates that modern stabilisers incorporating harmonically compensated saturated reactors, particularly of the treble tripler type, can now meet the technical and economic requirements of the hybrid scheme described in this paper. The main points of comparison between the shunt stabilised line and compensation by series capacitors and linear shunt reactors refer to stability and overvoltage protection.