FIELD: electrical equipment.
SUBSTANCE: invention relates to electrical engineering and is intended for relay protection against short-circuits of buses and partially cells of distribution devices, first of all, medium voltage 6–35 kV of electric stations and substations of power system. In the method of multi-agent differential protection of buses, which consists in the fact that secondary currents of each current transformer are measured, a differential current is formed by a phase, proportional to difference of secondary currents at input and output of protected buses, generating logic signal of protection measuring element actuation, at each connection of bus system, microprocessor terminal agent is installed, integrating terminals by local information control network, from each agent terminal circularly digital parameters of currents are transmitted to each half-period, generating and transmitting logic signal on saturation of magnetic conductor of current transformer, for this purpose, in time interval from moment of occurrence of short circuit to moment of saturation is read out samples of current are calculated amplitude value of current, determining moment corresponding to appearance of amplitude value, and measuring current, then calculating ratio of calculated and measured currents; if ratio is in range from 1 to allowable level of 1.1, then logical signal on saturation is formed equal to zero, if the ratio exceeds the permissible level, the maximum value of which is 1.1, then the logic signal on saturation is formed equal to one; checking condition matching, namely, absence of saturation signal in any of agent terminals on previous half-period, presence of a saturation signal in any agent terminal and presence of a signal from the power supply connection terminal agent to increase current at the current period to a value greater than the maximum current without a short circuit; in case conditions coincide, logic trigger of protection measuring element is blocked; otherwise, according to the signal of protection measuring device actuation, the switches are disconnected; the disconnection signal from protection is generated according to the declared logic expression.
EFFECT: technical result consists in blocking the operation of differential protection of busbars in case of signs of saturation of magnetic circuit of current transformer of feeder at external short circuit.
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