METHOD OF PROTECTION AGAINST SINGLE-PHASE EARTH FAULTS

摘要

FIELD: electrical engineering.;SUBSTANCE: invention relates to electrical engineering. The method of protection against a single-phase earth fault in an electrical network consists in measuring the instantaneous values ​​of the zero sequence current and the rate of rise of the instantaneous values ​​of the zero sequence voltage of the transient process at the moment of the failure of the isolation of the mains phase to the ground, calculating the integral value calculated in the specified time interval of the protection operation, and the formation of a control action on the executive protection organs when the integral value of the set value is exceeded, while the coefficient of mutual correlation of instantaneous values ​​of zero sequence currents and the rate of rise of instantaneous values ​​of zero sequence voltage is used as an integral value, N discrete values ​​of the speed are preliminarily formed simultaneously or with the minimum possible delay changes in the zero-sequence voltage and N discrete values ​​of the zero-sequence current shifted by j samples, determine the coefficient of interaction me correlations according to the ratio; ;where d3Uo (n) = (U₂-U₁)/ΔТ is the n-th discrete value of the time derivative of the zero-sequence voltage, U₁, U₂ are the results of two consecutive values ​​of the zero-sequence voltage of the n-th cycle of generation of discrete values, ΔT is the interval time between two consecutive moments of formation of a discrete value; 3Io(n-j)-(n-j)-th discrete value of zero sequence current; N is the number of discrete values, the calculated value of the cross-correlation coefficient is compared with a given value (setpoint) and a decision is made on the formation of a control action.;EFFECT: improving the reliability of protection. ;1 cl, 1 dwg