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NON-OSCILLATORY REMOVAL OF TRANSIENTS IN A POWER SYSTEM INCLUDING SEVERAL TIE-LINES
NON-OSCILLATORY REMOVAL OF TRANSIENTS IN A POWER SYSTEM INCLUDING SEVERAL TIE-LINES
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机译：包含多条联络线的电力系统中的瞬态非振荡去除
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摘要
In a power transmission system involving parallel tie-lines extending between a generating station and a large power grid, transients are removed, upon the opening of one tie-line, by inserting two capacitors in series with the system for a first time interval. The capacitors produce a first capacitive reactance of a sufficiently high value to provide a negative power transmission characteristic so that there is a reverse flow of power between the grid and the generating station. In this way the inertia of the generators at the generating station is accelerated toward an increased power angle in accordance with the decreased power transmission characteristic due to the opening of the one tie-line. After the first time interval, one of the capacitors is short-circuited so as to reduce the capacitive reactance to a second lower value. In this way a positive power transmission characteristic is produced of a greater magnitude than the characteristic in the absence of capacitive reactance. Thus, the inertia of the generators at the generating station is decelerated. After a second time interval, both capacitors are short-circuited to remove all capacitive reactance from the circuit. The time intervals are such as to attain the increased power angle (which is the steady state operating angle under post-fault conditions) which equalizes the energies representing acceleration and deceleration so as to obviate any oscillations. Instead of using the high value of capacitive reactance during the first time interval, an inductive reactance may be employed, which provides a reduced power transmission characteristic so that acceleration of the generating station is produced. The invention is also applicable to other transitions in which it is desirable to prevent oscillation of the power angle of the generating system. When the second tie-line is brought back into service, the power angle may be reduced without oscillation, by switching in a relatively low value of capacitive reactance for a first time interval, so as to increase the power transmission characteristic. During a second time interval, the power transmission characteristic is reduced or reversed by switching in an inductive reactance or a high value of capacitive reactance. If the electrical load on the generating station increases abruptly, the power angle can be increased the necessary amount without oscillation by switching in a high value of capacitive reactance, or an inductive reactance, for a first time interval, following which a lower value of capacitive reactance is switched in for a second time interval. Likewise, an abrupt decrease in load can be accommodated by switching in a relatively low value of capacitive reactance for a first time interval, following which a higher value of capacitive reactance, or an inductive reactance, is switched in for a second interval. In each case, maximum acceleration is followed by maximum deceleration, or vice versa, to bring about the transition in minimum time, without oscillation.
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