CN201188539Y

CN201188539Y - Resonance damping device for power distribution network PT

Info

Publication number: CN201188539Y
Application number: CNU2008200802553U
Authority: CN
Inventors: 尹忠东; 周丽霞; 任智慧; 王苗苗; 吴志明; 杨晓静; 王永武
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2008-04-28
Filing date: 2008-04-28
Publication date: 2009-01-28
Anticipated expiration: 2018-04-28

Abstract

The utility model relates to a PT resonance damp device of a distribution network, which belongs to the technical field of the control protection. The device comprises a damp reactor (4), inverse parallel controllable silicon (5) and a trigger controller (6), wherein, the damp reactor (4) and the inverse parallel controllable silicon (5) are connected in series to form a damp control main circuit (3) and are connected to the port of a PT secondary side opening triangle winding. The utility model has the advantages that the PT resonance damp device can effectively distinguish the resonance and single-phase grounding failure, accurately actualize the damp control of the resonance, and exactly indicate the occurrence of frequency demultiplication, fundamental frequency and high-frequency ferromagnetic resonance or single-phase grounding failure for the system. The device does not influence the normal operation of the electric fence and the collection of zero-sequence signals of the system, and does not generate ultraharmonics and other interference signals.

Description

Power distribution network PT resonance damping device

Technical field

The utility model belongs to power distribution network control resist technology field, and a kind of power distribution network PT resonance damping device particularly is provided.

Background technology

In the distribution network of 6～35kV, system neutral generally adopts earth-free mode.Be connected to the electromagnetic potential transformer (PT) of measuring and monitoring insulation against ground on the system busbar, when the bus-tie circuit breaker closing operation takes place, the single-phase arc grounding of circuit disappears automatically or during situation such as system loading acute variation, the transient state impact process that is produced may excite the ferro resonance phenomenon between PT and three-phase conducting wire direct-to-ground capacitance, cause the overcurrent among system's overvoltage and the PT, make that the high-voltage wire iron-melting fusing of flashover, PT over the ground takes place weak insulator arrangement in the system, even burn PT.The ferro resonance of PT is that appearance is the most frequent in the power distribution network, maximum a kind of Past Voltage within Power System causes the accident.

Summary of the invention

The purpose of this utility model is to provide a kind of power distribution network PT resonance damping device, can effectively distinguish resonance and single phase ground fault, the correct damping control of implementing resonance, and accurately frequency division, fundamental frequency, high-frequency iron magnetic resonance or single phase ground fault have taken place in indication mechanism.Device does not influence the normal operation of electrical network and the collection of system zero sequential signal; Do not produce high order harmonic component and other interference signal.

The utility model comprises: damping reactor 4, inverse parallel controllable silicon 5, triggering controller 6.It is open-minded that controller 6 sends the gate pole trigger impulse control silicon controlled of controllable silicon 5.

Damping reactor

4 and 5 series connection of inverse parallel controllable silicon constitute damping control main circuit 3, are connected to PT secondary side open delta winding 2 ports.

Under the normal condition, SCR control pulse controlled device 6 is blocked, and controllable silicon is in blocking state, and open delta winding 2 ports of PT secondary side are open-circuit condition.

In case resonance or system single-phase earth fault take place, residual voltage can appear in open delta winding 2 ports, this voltage will trigger the frequency that controller 6 starts fast fourier algorithm (FFT) detectable voltage signals, remove silicon controlled pulse blocking then, trigger controllable silicon.Controllable silicon enters fully conducting state, and the equivalence of PT open delta winding 2 ports inserts damping reactor 4.

For resonance, damping reactor 4 absorbs resonant energy, reaches the harmonic elimination purpose, behind two power frequency cycles, controller 6 blocks the gate pole trigger impulse of controllable silicon 5, and controllable silicon 5 enters blocking state constantly at the current over-zero of PT open delta winding 2, and port voltage is near zero volt; If single phase ground fault though the input of damping reactor can not eliminated single phase ground fault, has limited PT open delta winding 2 electric currents, protected PT.Behind 2 power frequency cycles, controllable silicon recovers blocking-up, and PT open delta winding 2 ports are got back to open-circuit condition, but the bigger residual voltage that port voltage still produces for ground connection.The fault that thus can decision-making system takes place is resonance or single-phase earthing.

As seen, device does not influence the normal operation of electrical network and the collection of system zero sequential signal; Do not produce high order harmonic component and other interference signal.

Advantage of the present utility model is: a kind of power distribution network PT resonance damping device that is provided, can effectively distinguish resonance and single phase ground fault, the correct damping control of implementing resonance, and accurately frequency division, fundamental frequency, high-frequency iron magnetic resonance or single phase ground fault have taken place in indication mechanism.Device does not influence the normal operation of electrical network and the collection of system zero sequential signal; Do not produce high order harmonic component and other interference signal.

Description of drawings

Fig. 1 is a kind of power distribution network PT resonance damping device system diagram of the present utility model.Wherein, winding 1 of PT, PT open delta winding 2, controllable damping main circuit 3.E1, E2, E3 are respectively system's three-phase voltage, and C0 is a line mutual-ground capacitor.

Fig. 2 is a kind of power distribution network PT resonance damping device figure of the present utility model.Wherein, PT open delta winding 2, controllable damping main circuit 3, damping reactor 4, inverse parallel controllable silicon 5, controller 6.Controller 6 sends or block the gate pole trigger impulse of controllable silicon 5 can realize opening of inverse parallel controllable silicon 5 and natural turn-off function.

Fig. 3 excites the Subharmonic Resonance experimental waveform for the simulation 10kV distribution network systems that the utility model carries out.Wherein, passage 1 (ch1) expression A phase voltage, passage 2 (ch2) expression B phase voltage, passage 3 (ch3) expression C phase voltage, passage 4 (ch4) expression open delta winding voltage.

Fig. 4 is the harmonic elimination experimental waveform of a kind of power distribution network PT resonance damping device of the present utility model.Wherein, passage 5 (ch5) expression A phase voltage, passage 6 (ch6) expression B phase voltage, passage 7 (ch7) expression C phase voltage, passage 8 (ch8) expression open delta winding voltage.

Embodiment

Fig. 1～Fig. 4 is a kind of embodiment of the present utility model.The controllable damp device main circuit is damping reactor 4 of series connection after two thyristor 5 inverse parallels, forms the main circuit 3 of a thyristor controlled reactor topological structure, and the two ends of main circuit 3 are connected to the two ends of PT secondary side open delta winding 2.Controller 6 by the 89C51 single-chip microcomputer as control core, by the measurement of AD574 enforcement to the port residual voltage of PT open delta winding, P1 mouth by 89C51 produces trigger impulse, and pulse is by implementing the gate pole triggering to two inverse parallel controllable silicons 5 in the device main circuit behind photoelectric isolating device, Darlington power driving circuit and the pulse transformer.Controller 6 sends or block trigger impulse can control opening of inverse parallel controllable silicon 5 and shutoff naturally.

Under the normal condition, SCR control pulse controlled device 6 is blocked, and controllable silicon is in blocking state, and open delta winding 2 ports of PT secondary side are open-circuit condition.In case resonance or system single-phase earth fault take place, and residual voltage can appear in open delta winding 2 ports, this voltage will excite controller 6 to start the frequency of fft algorithm detectable voltage signals, remove silicon controlled pulse blocking then, trigger controllable silicon.Controllable silicon enters fully conducting state, and damping reactor 4 is inserted at the two ends of PT open delta winding 2.For resonance, reactor can absorb resonant energy, reaches the harmonic elimination purpose; If single phase ground fault, reactor can limit PT open delta winding 2 electric currents, protection PT.Behind 2 power frequency cycles, controllable silicon recovers blocking-up, and PT open delta winding 2 ports are got back to open-circuit condition.The resonance detection scheme of controllable damp device is, on-line monitoring PT secondary side open delta winding port voltage, under the normal condition, PT open delta winding port voltage is about zero, if PT ferro resonance or single phase ground fault take place in system, then residual voltage can appear in PT open delta winding port.Start the main frequency spectrum that fast Fourier transform (FFT) extracts voltage signal with this residual voltage, can directly judge frequency division or high-frequency resonant have taken place, implement the damping action.If the zero sequence signal frequency that FFT extracts is a fundamental frequency, then implement damping control in advance, if after the controllable damp device action, the port zero sequence signal disappears, what then can decision-making system have just taken place is fundamental resonance, if after the controllable damp device action, the port zero sequence signal still exists, then system's generation single phase ground fault.

Claims

1, a kind of power distribution network PT resonance damping device, it is characterized in that: this device comprises: damping reactor (4), inverse parallel controllable silicon (5), triggering controller (6); Damping reactor (4) and inverse parallel controllable silicon (5) series connection constitute damping control main circuit (3), are connected to PT secondary side open delta winding (2) two ends.