Grounding direction relay system
A relay, ground fault technology, applied in circuit devices, electrical components, emergency protection circuit devices, etc., can solve problems such as failure to determine the direction of the fault
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no. 1 example
[0047] figure 2 is a block diagram of the functional processing unit of the first embodiment of the ground direction relay according to the present invention. can be used as figure 1 The digital processor 9 shown implements the ground direction relay. refer to figure 2 , the grounding direction relay is indicated by 10 as a whole. The relay 10 has a digital filter 10-1 that receives digital signals of voltage "V" and current "I" from the analog-to-digital converter 8, and outputs "v" and "i" filtered signals, respectively.
[0048] The ground direction relay 10 also generally has a zero-phase-sequence current calculation unit 10-2 which calculates the zero-phase-sequence current component "3I" of the self-current "i" using equation (1) shown below 0 ”, the current “i” is the output of the digital filter 10-1:
[0049] 3I 0m = i Am + i Bm + i Cm …(1)
[0050] where the subscript "m" represents the standard sampling time. Assume that data is sampled every 30 degree...
no. 2 example
[0079] Figure 9 is a block diagram showing the functional processing unit of the second embodiment of the ground directional relay according to the present invention. The grounding direction relay 11 of the second embodiment has a digital filter 10-1, a zero-phase-sequence current calculation unit 10-2 and a comparison unit 10-3, which are the same as figure 2 The ground directional relay 10 of the first embodiment shown has the same. In addition, the ground direction relay 11 has an absolute value comparison unit 10-4 that can receive the output of the zero-phase-sequence current calculation unit 10-2 and can calculate the absolute value of the zero-phase-sequence current. The grounding direction relay 11 also has a forward fault determination unit 10-5, which can receive the outputs of the comparison unit 10-3 and the absolute value comparison unit 10-4, and can determine whether the condition of "AND" is satisfied.
[0080] The absolute value comparison unit 10-4 can de...
no. 3 example
[0086] refer to Figure 11 and 12 A third embodiment according to the present invention has been described. Figure 11 is a block diagram showing a logic sequence circuit for generating a forward fault phase determination signal in the third embodiment. Instantaneous current-variation elements 19-A, 19-B and 19-C can detect changes in current. The instantaneous current-varying elements 19-A, 19-B and 19-C are sensitive and can detect phases in which a high impedance fault occurs. The instantaneous current-varying elements 19-A, 19-B and 19-C pass the current I at the basic sampling point (m) m The absolute value and the current I at the sampling point (m-12) m-12 The difference between the absolute values of to detect changes, the sampling point (m-12) is 1 cycle earlier than the basic sampling point, as shown in the following formula (7):
[0087] |ΔI| m =‖I m |-|I m-12 ‖≥K…(7)
[0088] where K is a constant corresponding to the sensitivity.
[0089] Such as Fig...
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