| 摘要 |
The invention relates to electrical engineering and it can be used for prevention of cascade faults, their localization and recovering of normal operation without staff participation. When a fault begins and the transmission lines that remain under operation are overloaded, before the stability is lost and the voltage fall avalanche is initiated, a power-deficient region is separated from the network, with its load and electric station, in the optimal cross-section, thus eliminating the transmission line overload and creating prerequisites for the process of recovering the normal operating condition within 1.5-3 minutes without personnel involvement with the help of the automatic means available. The offered procedure of elimination of a cascade-type fault (fig.1) is as follows: over a period of disconnection of a heavily loaded line (1) that creates a voltage avalanche with a risk of an electric stations' outage, the automatic system (I) snaps into action, which has no feedback and whose operation can therefore be unsuccessful, and, in case of onset of stability break-down, an asynchronous operation of system is liquidated by automatics (II), dividing the power system into parts in the asynchronous operation cross-section; a voltage fall avalanche caused by overloading of power transmission network, which is dangerous for electric stations, is eliminated and liquidated by separating the deficient region, with its load and electric stations (III), in the optimal cross-section, once voltage fall signs have arisen; in the deficient part the frequency fall is removed by the existing fast frequency off-loading automatics (IV), maintaining frequency in the range that is not hazardous for electric stations by applying a feedback; system (V) temporarily switches off some of the lines that are, under the conditions of reduced load, of no use for a short time, in order to avoid too high voltage that can occur owing to the capacitive power in the high-voltage line when load is shed, and after that: the slow off-loading automatics (VI) starts to operate, recovering the frequency up to the normal level and additionally switching off the necessary amount of consumers, the automatics (VII) joins together the separated parts of the power system supplying voltage to the consumers' lines after the frequency normalization signs appear, and automatics (IX) simultaneously connects to the electric power system the high-voltage lines that were previously disconnected.
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