CN103944151A - Ungrounded system multi-circuit parallel line different-phase two-point grounding protection method - Google Patents
Ungrounded system multi-circuit parallel line different-phase two-point grounding protection method Download PDFInfo
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Abstract
The invention relates to an ungrounded system multi-circuit parallel line different-phase two-point grounding protection method, and belongs to the field of ungrounded operation power system earth fault monitoring. When a negative-sequence overvoltage relay U2> and a zero-sequence overvoltage relay U0> work at the same time, it means that an asymmetric earth fault occurs, and meanwhile a low-voltage relay 1KV, a low-voltage relay 2KV and a low-voltage relay 3KV work and judge corresponding fault phases to be a phase A, a phase B and a phase C respectively; when the negative-sequence overvoltage relay U2> and the zero-sequence overvoltage relay U0> work at the same time, it means that the asymmetric earth fault occurs, and meanwhile zero-sequence current direction judgment components (1KP, 2Kp, ..., nKP) of parallel lines work to judge corresponding fault lines L1, L2,...,Ln respectively. The method overcomes the defects that in the prior art, it can only be monitored whether a system is grounded, lines and phases can not be selected, and line selection is influenced by unbalanced current of a zero-sequence current filter.
Description
Technical field
The present invention relates to the guard method of 2 ground connection mutually of many times parallel circuit different names of a kind of isolated neutral system, belong to the ground fault detection field of earth-free operation electric power system.
Background technology
In isolated neutral system, while there is single phase ground fault, because the electric current of fault point is very little, and line voltage between three-phase still keeps symmetrical, the power supply of load is not affected, therefore, all allow in the ordinary course of things to continue operation 1～2 hour, and needn't trip immediately.
But fault phase voltage to earth reduces when isolated neutral system generation single phase ground fault, other two phase-to-ground voltage raises 1.73 times.For preventing that fault from further expanding, should send in time signal, so that operations staff takes measures.Especially in many times parallel circuits of isolated neutral system, different name must be taken measures to excise one time mutually faulty line when 2 ground connection.
Current existing isolated neutral system single phase earthing protection method has three classes.
One class is that the residual voltage occurring on system busbar while utilizing isolated neutral system generation single-phase earthing judges whether to occur earth fault, and whether this method can only have earth fault to occur in monitoring system, can not route selection and phase selection.
One class is that while utilizing isolated neutral system generation single-phase earthing, the zero-sequence current feature large compared with non-fault line on faulty line realizes; monitor all outlet zero-sequence currents; although the method can be monitored the circuit that is out of order in theory; realize route selection; but owing to being subject to the impact of zero-sequence current filter unsymmetrical current, in the time that the capacitance current capacitance current less or protected circuit of system is larger, cannot make accurate judgment.
One class is that while utilizing isolated neutral system generation single-phase earthing, on faulty line, the direction of zero-sequence current is for line flows is to bus, and on non-fault line, the direction of zero-sequence current is that bus flows to circuit, realizes route selection according to this feature, but can not phase selection.
Summary of the invention
The invention provides the guard method of 2 ground connection mutually of many times parallel circuit different names of a kind of isolated neutral system, for overcoming whether a monitoring system in prior art has ground connection and can not route selection and phase selection, route selection be subject to the impact, route selection of the capacitance current of zero-sequence current filter unsymmetrical current and system and deficiency that can not phase selection.
Technical scheme of the present invention is: the guard method of 2 ground connection mutually of many times parallel circuit different names of a kind of isolated neutral system, and the concrete steps of described method are as follows:
A, zero sequence current mutual inductor (1TA, 2TA ..., nTA) 4 be installed in each time parallel circuit of isolated neutral system (L1, L2 ..., Ln) on 1, on isolated neutral system bus 3, the threephase potential transformer TV2 of installing experiences A phase on bus, B phase, C three phase-to-ground voltages mutually;
B, threephase potential transformer TV2 secondary side a, the little bus of b, c are connected on negative phase-sequence overvoltage relay U2> through negative sequence voltage filter output voltage; Threephase potential transformer TV2 open-delta output voltage is connected on zero sequence overvoltage relay U0>;
On C, threephase potential transformer TV2 secondary side a, the little bus of b, c, get each phase-to-ground voltage, be connected to 3 under-voltage replays; Wherein, A phase-to-ground voltage meets under-voltage replay 1KV, and B phase-to-ground voltage meets under-voltage replay 2KV, and C phase-to-ground voltage meets under-voltage replay 3KV:
When negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously, illustrate asymmetric earth fault has occurred, it is A phase, B phase, C phase that corresponding fault phase is judged respectively in three under-voltage replay 1KV, 2KV, 3KV actions simultaneously;
D, each time parallel circuit of isolated neutral system (L1, L2 ..., Ln) 1 zero-sequence current direction judgment component (1KP, 2KP ..., nKP), use zero sequence directional relay is realized, and reacts on the phase place between its input voltage and input current and moves;
When negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously, illustrate asymmetric earth fault occurred, simultaneously the zero-sequence current direction judgment component of parallel circuit (1KP, 2KP ..., nKP) action judge respectively corresponding faulty line be L1, L2 ..., Ln.
Described negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously and experience negative sequence voltage and residual voltage for threephase potential transformer TV2.
Described under-voltage replay 1KV, 2KV, 3KV action is experienced corresponding A phase, B phase, the reduction of C phase-to-ground voltage for threephase potential transformer TV2.
The potential winding connecting system bus threephase potential transformer TV2 secondary side residual voltage of described zero sequence directional relay
, the current coil of each zero sequence directional relay access respectively zero sequence current mutual inductor on each circuit (1TA, 2TA ..., nTA) 4 secondary side zero-sequence currents
; The sensitiveest angle of zero sequence directional relay value is 90 °.
The zero-sequence current direction judgment component of described parallel circuit (1KP, 2KP ..., nKP) action for zero-sequence current direction be positive direction.
Operation principle of the present invention is:
Suppose isolated neutral system have n return parallel circuit (L1, L2 ..., Ln), the situation (as shown in Figure 2) during below with L1 circuit A phase ground connection in many times parallel circuits of isolated neutral system and L2 circuit B phase ground connection, accompanying drawings the inventive method principle is:
1, in the time that ground connection occurs many times 2 of parallel circuit different names phases of isolated neutral system, system there will be negative sequence voltage and residual voltage, and on simultaneity factor bus, two Earth Phase voltage to earths reduce;
2, in the time that ground connection occurs many times 2 of parallel circuit different names phases of isolated neutral system, the zero-sequence current on L1 circuit and L2 circuit is formed by the non-fault element capacitive earth current of total system, and residual voltage is ahead of 90 ° of zero-sequence currents; Zero-sequence current on other each parallel circuit is formed by itself capacitive earth current, and residual voltage lags behind 90 ° of zero-sequence currents;
3, the threephase potential transformer TV2 open-delta being connected on bus is experienced system zero sequence voltage; Be connected to negative sequence voltage filter on voltage transformer TV2 secondary side a, the little bus of b, c and experience system negative sequence voltage; Voltage transformer TV experiences A phase and B phase-to-ground voltage reduces;
4, negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move, simultaneously two under-voltage replay 1KV, 2KV actions in three under-voltage replay 1KV, 2KV, 3KV, judging fault phase is A phase, B phase;
5, to be ahead of the angle of input zero-sequence current be 90 ° to circuit L1 and circuit L2 zero-sequence current direction judgment component zero sequence directional relay 1KP, 2KP input residual voltage, zero sequence directional relay 1KP, 2KP action;
6, negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move, zero sequence directional relay 1KP, 2KP action simultaneously, and judging faulty line is circuit L1 and circuit L2;
Thus, realize phase selection and the route selection of 2 ground connection mutually of many times parallel circuit different names of isolated neutral system, judged fault phase and faulty line.
The invention has the beneficial effects as follows:
Form simply, use the impression of zero sequence current mutual inductor on system busbar voltage transformer and each circuit to form input signal; It is simple, clear that logic judgement forms.
Overcome whether a monitoring system in prior art has ground connection and can not route selection and phase selection, route selection be subject to the impact, route selection of the capacitance current of zero-sequence current filter unsymmetrical current and system and deficiency that can not phase selection.
According to phase selection in the inventive method and route selection flow process, can realize the fault judgement of 2 ground connection mutually of many times parallel circuit different names of isolated neutral system, complete phase selection and route selection simultaneously.Thereby, realize a wherein faulty line of excision selectively, be convenient to the processing of operations staff to fault phase simultaneously.
Brief description of the drawings
Fig. 1 is institute's use instrument transformer installation position schematic diagram in the present invention;
Fig. 2 is that in the present invention, 2 ground connection zero-sequence currents of many times parallel circuit different names phases of isolated neutral system flow to schematic diagram;
Fig. 3 is voltage relay ac voltage circuit figure in the present invention;
Fig. 4 is directional power relay input signal schematic diagram in the present invention;
Fig. 5 is phase selection logic relation picture in the present invention;
Fig. 6 is route selection logic relation picture in the present invention;
Each label in figure: 1 be each time parallel circuit of isolated neutral system (L1, L2 ..., Ln), 2 be threephase potential transformer TV, 3 for isolated neutral system bus, 4 for zero sequence current mutual inductor (1TA, 2TA ..., nTA).
Embodiment
Embodiment 1: as shown in Fig. 1-6, the guard method of 2 ground connection mutually of many times parallel circuit different names of a kind of isolated neutral system, the concrete steps of described method are as follows:
A, zero sequence current mutual inductor (1TA, 2TA ..., nTA) 4 be installed in each time parallel circuit of isolated neutral system (L1, L2 ..., Ln) on 1, on isolated neutral system bus 3, the threephase potential transformer TV2 of installing experiences A phase on bus, B phase, C three phase-to-ground voltages mutually;
B, threephase potential transformer TV2 secondary side a, the little bus of b, c are connected on negative phase-sequence overvoltage relay U2> through negative sequence voltage filter output voltage; Threephase potential transformer TV2 open-delta output voltage is connected on zero sequence overvoltage relay U0>;
On C, threephase potential transformer TV2 secondary side a, the little bus of b, c, get each phase-to-ground voltage, be connected to 3 under-voltage replays; Wherein, A phase-to-ground voltage meets under-voltage replay 1KV, and B phase-to-ground voltage meets under-voltage replay 2KV, and C phase-to-ground voltage meets under-voltage replay 3KV:
When negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously, illustrate asymmetric earth fault has occurred, it is A phase, B phase, C phase that corresponding fault phase is judged respectively in three under-voltage replay 1KV, 2KV, 3KV actions simultaneously;
D, each time parallel circuit of isolated neutral system (L1, L2 ..., Ln) 1 zero-sequence current direction judgment component (1KP, 2KP ..., nKP), use zero sequence directional relay is realized, and reacts on the phase place between its input voltage and input current and moves;
When negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously, illustrate asymmetric earth fault occurred, simultaneously the zero-sequence current direction judgment component of parallel circuit (1KP, 2KP ..., nKP) action judge respectively corresponding faulty line be L1, L2 ..., Ln.
Described negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously and experience negative sequence voltage and residual voltage for threephase potential transformer TV2.
Described under-voltage replay 1KV, 2KV, 3KV action is experienced corresponding A phase, B phase, the reduction of C phase-to-ground voltage for threephase potential transformer TV2.
The potential winding connecting system bus threephase potential transformer TV2 secondary side residual voltage of described zero sequence directional relay
, the current coil of each zero sequence directional relay access respectively zero sequence current mutual inductor on each circuit (1TA, 2TA ..., nTA) 4 secondary side zero-sequence currents
; The sensitiveest angle of zero sequence directional relay value is 90 °.
The zero-sequence current direction judgment component of described parallel circuit (1KP, 2KP ..., nKP) action for zero-sequence current direction be positive direction.
Embodiment 2: as shown in Fig. 1-6, the guard method of 2 ground connection mutually of many times parallel circuit different names of a kind of isolated neutral system, the concrete implementation step of described method is as follows:
Isolated neutral system have n return parallel circuit (L1, L2 ..., Ln), wherein L1 circuit A phase single-phase earthing, L2 circuit B phase single-phase earthing, as shown in Figure 2.
In the time of L1 circuit A phase single-phase earthing and L2 circuit B phase single-phase earthing, on system busbar, threephase potential transformer TV experiences negative sequence voltage and residual voltage, and negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously;
Meanwhile, on system busbar, threephase potential transformer TV2 experiences A phase and the reduction of B phase-to-ground voltage, under-voltage replay 1KV and 2KV action, and judging fault phase is A phase and B phase;
Meanwhile, zero-sequence current direction judgment component 1KP and the 2KP of parallel circuit are judged as positive direction, and circuit L1 is selected in 1KP and 2KP action and circuit L2 is faulty line.
Thus, realize phase selection and the route selection of 2 ground connection mutually of many times parallel circuit different names of isolated neutral system, judged fault phase and faulty line.
By reference to the accompanying drawings the specific embodiment of the present invention is explained in detail above, but the present invention is not limited to above-mentioned execution mode, in the ken possessing those of ordinary skill in the art, can also under the prerequisite that does not depart from aim of the present invention, make various variations.
Claims (5)
1. many times parallel circuit different names of isolated neutral system guard method for 2 ground connection mutually, is characterized in that: the concrete steps of described method are as follows:
A, zero sequence current mutual inductor (1TA, 2TA ..., nTA) (4) be installed in each time parallel circuit of isolated neutral system (L1, L2 ..., Ln) (1) upper, the threephase potential transformer TV(2 of the upper installing of isolated neutral system bus (3)) experience A phase on bus, B phase, C three phase-to-ground voltages mutually;
B, threephase potential transformer TV(2) secondary side a, b, the little bus of c be connected on negative phase-sequence overvoltage relay U2> through negative sequence voltage filter output voltage; Threephase potential transformer TV(2) open-delta output voltage is connected on zero sequence overvoltage relay U0>;
C, threephase potential transformer TV(2) get each phase-to-ground voltage on secondary side a, b, the little bus of c, be connected to 3 under-voltage replays; Wherein, A phase-to-ground voltage meets under-voltage replay 1KV, and B phase-to-ground voltage meets under-voltage replay 2KV, and C phase-to-ground voltage meets under-voltage replay 3KV:
When negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously, illustrate asymmetric earth fault has occurred, it is A phase, B phase, C phase that corresponding fault phase is judged respectively in three under-voltage replay 1KV, 2KV, 3KV actions simultaneously;
D, each time parallel circuit of isolated neutral system (L1, L2 ..., Ln) (1) zero-sequence current direction judgment component (1KP, 2KP ..., nKP), use zero sequence directional relay is realized, and reacts on the phase place between its input voltage and input current and moves;
When negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move simultaneously, illustrate asymmetric earth fault occurred, simultaneously the zero-sequence current direction judgment component of parallel circuit (1KP, 2KP ..., nKP) action judge respectively corresponding faulty line be L1, L2 ..., Ln.
2. many times parallel circuit different names of isolated neutral system according to claim 1 guard method of 2 ground connection mutually, is characterized in that: described negative phase-sequence overvoltage relay U2> and zero sequence overvoltage relay U0> move as threephase potential transformer TV(2 simultaneously) experience negative sequence voltage and residual voltage.
3. many times parallel circuit different names of isolated neutral system according to claim 1 guard method of 2 ground connection mutually, is characterized in that: described under-voltage replay 1KV, 2KV, 3KV action are threephase potential transformer TV(2) experience corresponding A phase, B phase, C phase-to-ground voltage and reduce.
4. many times parallel circuit different names of isolated neutral system according to claim 1 guard method of 2 ground connection mutually, is characterized in that: the potential winding connecting system bus threephase potential transformer TV(2 of described zero sequence directional relay) secondary side residual voltage
, the current coil of each zero sequence directional relay access respectively zero sequence current mutual inductor on each circuit (1TA, 2TA ..., nTA) (4) secondary side zero-sequence current
; The sensitiveest angle of zero sequence directional relay value is 90 °.
5. many times parallel circuit different names of isolated neutral system according to claim 1 guard method of 2 ground connection mutually, is characterized in that: the zero-sequence current direction judgment component of described parallel circuit (1KP, 2KP ..., nKP) action for zero-sequence current direction be positive direction.
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| CN201410140833.8A CN103944151B (en) | 2014-04-10 | 2014-04-10 | A kind of guard method of many times parallel circuit different name phase two points ground fault of isolated neutral system |
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| CN201410140833.8A CN103944151B (en) | 2014-04-10 | 2014-04-10 | A kind of guard method of many times parallel circuit different name phase two points ground fault of isolated neutral system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107064741A (en) * | 2017-04-06 | 2017-08-18 | 广西电网有限责任公司电力科学研究院 | A kind of 2 points of successive ground fault line selecting methods of distribution network line different name phase |
| CN109818327A (en) * | 2019-03-02 | 2019-05-28 | 安徽云汉智能科技有限公司 | A kind of early warning type three-phase electic protection method and apparatus |
| CN113687188A (en) * | 2021-09-14 | 2021-11-23 | 广东电网有限责任公司 | Fault line selection method and device based on two-stage zero-sequence power change |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107064741A (en) * | 2017-04-06 | 2017-08-18 | 广西电网有限责任公司电力科学研究院 | A kind of 2 points of successive ground fault line selecting methods of distribution network line different name phase |
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| CN109818327A (en) * | 2019-03-02 | 2019-05-28 | 安徽云汉智能科技有限公司 | A kind of early warning type three-phase electic protection method and apparatus |
| CN113687188A (en) * | 2021-09-14 | 2021-11-23 | 广东电网有限责任公司 | Fault line selection method and device based on two-stage zero-sequence power change |
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