DEVICE FOR CENTRALIZED PROTECTION AGAINST SINGLE-PHASE GROUND FAULTS IN DISTRIBUTION NETWORKS OF MEDIUM VOLTAGE Russian patent published in 2025 - IPC H02H3/16 

FIELD: electrical engineering; electric power industry.

SUBSTANCE: centralized protection device contains n zero-sequence current transformers according to the number of connections; zero-sequence voltage measuring transformer; n current couplers, voltage coupler, n input current parameter generators, input voltage parameters generator, n network neutral mode program switches with two inputs and one output each, input current values comparison circuit with n inputs and n discrete outputs, unit of long-term memory elements of input actuation signals of the main algorithm with discrete n inputs and outputs, inputs for fixing and resetting information from long-term memory elements. Device also comprises a first blocking input signal inversion element, second element of logical inversion of input signal of protection start, blocking unit for comparison of values of input currents at extinguishing of grounding arc, unit for recognizing arc earth faults, maximum voltage starting element, circuit of centralized directional pulse protection against single-phase ground faults with n current signal inputs, one voltage signal input, discrete input of protection start and n+1 discrete outputs, logical unit for generation of output signals and visual display of output information. Secondary windings of zero-sequence current transformers are connected to inputs of current interface devices. Primary winding of the zero-sequence voltage measuring transformer is connected to the busbar section of the supply substation, and the “open delta” winding is connected to the input of the voltage coupler. 1st output of the voltage parameter generator is connected to the input of the differentiator of the blocking unit of the input current values comparison circuit. Output of the above blocking unit is connected to a discrete input of fixation of the unit of long-term memory elements through the first element of logical inversion of the input blocking signal. Input of the maximum voltage trigger is connected to 3rd output of the voltage parameter generator, and the output is connected to the long-term memory elements unit reset discrete input through the second logical inversion element of the input protection start signal, (n+2)-th discrete input of logical unit for generation of output signals and visual display of output information and discrete input of start-up of centralized directional pulse protection circuit.

EFFECT: higher selectivity, stability of operation and versatility of centralized protection with all types of considered SPGF in cable and mixed cable-air distribution networks of medium voltage, operating with isolated neutral, with compensation of capacitive currents or with resistive earthing of neutral.

1 cl, 5 dwg