Operasyon Metoda ji bo PT Resonance li ser 500kV GIS Switching Station

1. Resonansin Sêbepan

500kV GIS qamış karê ya di ser bîsaya "birincil cihazên zekî û duçincil cihazên taybetkirin" de hate çêkirin. Partiya PT li tarafê bihêrkirî ya bihêr navnîş nehatiye ji bo nivîsêkê re hatiye pêserast kirin. Li ser analîzeya grafikên kesandina xeta, dema ku kureya 5021 veqetand, kapasîyantîna fraqtur û PT serdema ekar kirin. Mezin, bihêr dengê bus, di navbera PT inductance da, yekta werger û endamên induktîf dikin. Kapasîyantî şêtibandiye û resonans peyda kir.

Dermega ku amperajê piştî seddekerdaneke ji 1 saet û 40 deqe berdibe, riskeka hejûn û girtina PT vêne. Cihazek ekuivalent derbas dibe ku amperiya (Es), kureya (CB), kapasîyantîya fraqtur (Cs), kapasîyantîya bus-to-zemin (Ce), û rezîstansa û induktansa kelekê primîr (Re, Lcu) dibat.

Li ser rastîniya sêbepê, hêla duhemîn hatiye nikirin. Binihêriya rizgar PT, rezîstansa DC, û biha SF₆ gas nehatiye kontrol kirin û çendina anormaliyetek nedin. Ji ber ku PT elektromagnetîk taybetkirina inductor non-linear û core ferromagnetic e û komponentên cihazan GIS kapasîyantîyan hene, li ser senaryoyên taybet, LC serî circuit şertên resonansê hate pêk kirin, li vir çend rojan resonance.

2. Çareserzanên Şînî yên Elîtkirina Zanîn
2.1 Pirsgara Çareseri

Resonans PT her çend li ser stasyonên qamışkarîya 500kV GIS pirse bide. Penetrasyona materialên ferromagnetîk biguherîne bi mezinahiya mezanî: her çend mezanîya elektrîk bigere → guhertina mezanîya elektrîkê berge. Piştî seddekerdaniya, penetrasyon ên di rêja wekînê de dibe. Bi biguherîna berc û her çend penetrasyonê biçine. Li ser formulêya coil induction:

(N ji roja tevliya, μ ji penetrasyon, S ji rûnda herêmî yên magîn, û l_m ji hêla herêmî yên magîn), tevlîya û parametrekan magînên PT elektromagnetîk constant ne, û indiktansiya linear li ser penetrasyon; her çend core ferromagnetic seddekerdibe, penetrasyon ên biçine, indiktansiya biçine, û endamên non-linear dikin. Her çend bihêr dengê low-frequency li ser circuit pirse bibe, core PT seddekerdibe, indiktansiya eqvalent biçine, û amperiya winding excitation hundreds of times berge bibe, li vir çend rojan resonance heating.

Ji bo resonans, çareseran jêr hatine pirsgirî kirin:

• Guhertina rawa-veqetandin: Dema ku bus de-energizing be, yekem PT veqetand, past bus; dema energizing, bus first charge, past PT operation put. Ev çend şertên resonans biguheze, lê rawa-veqetandin guhertin dibaye û PT disconnector hewce ye.

• Rakirina capacitance fraqtur kureya: Ev çend şertên resonans rakirin, lê interrupting capacity kureya biçine.

• Pêserastkirina damping resistance: Li ser vêstergirina taybet, damping resistance bi cable set remaining bus PT pêserast bikin bi tenê kirina overvoltage û overcurrent.

2.2 Împelementasyonê Xezal

PT incoming-line ya 500kV GIS switching station di navbera de-energization de her çend resonance pirse bid, PT girt û çend operasyon cihazan biber. Di navbera incoming-line de-energization operasyon (hot standby → cold standby, etc.), PT hala resonance pirse bid. Berê PT parameters hesab kirin, numera turns primary/secondary winding guhertin kirin bi tenê kirina flux density û guhertina inductance; anti-resonance coil install kirin, û new PT û incoming-line PT guhertin. Piştî şopandin û istatisitik, çend resonance li ser stasyon nedin û cihazan normal opera kirin.

3. Çareser Preventive: Install Automatic Resonance Elimination Equipment

Her çend PT bus directly connected to the GIS bus, PT û bus-to-ground resistances not considered. Let PT inductance be L and bus-to-ground capacitance be C; the two are paralleled to form an impedance Z, and the calculation formula is

By installing automatic resonance elimination equipment, resonance can be suppressed based on impedance characteristics.

To reduce PT resonance impacts on 500kV GIS incoming-line PTs, air switches and nonlinear resistors are added to PT residual voltage windings (via coordination with manufacturers during full shutdowns) for automatic resonance elimination. An emergency plan for no-load bus resonance failure is required.

500kV GIS busbars use open-type installation; other devices are SF₆-insulated (small footprint, high reliability, 20-year+ maintenance intervals, as used in the Three Gorges Project). Reliable automatic resonance eliminators (e.g., LXQ-type with SiC, compact and easy to install; WXZ196 microcomputer-based, high-integration for real-time harmonic elimination) can prevent resonance.

3.2 Operating Regulation Improvements

For 500kV GIS operation:

• Pre-analysis: Identify PT resonance risks; clarify roles for power/NCS operators.

• Device control: Before shutting down the last circuit breaker, separate the bus. Close K1/K2 in the PT box; at the station entrance, activate the bus resonance eliminator (close K3, prepare resistors).

• Real-time monitoring: NCS tracks circuit breakers and bus voltages. Zero voltage = no resonance; fluctuating voltage = resonance detected.

• Response: For resonance, close K3 to engage resistors. If ineffective, open circuit breaker disconnectors for manual elimination.

4. Summary

During 500kV GIS design, simulate bus PT resonance to select robust PTs (prevent core saturation during switching). For existing resonance, take targeted actions (e.g., bus/PT replacement) to ensure safe operation. This “prevention-operation-design” system enhances anti-resonance capabilities.