Gwọ́n Ọ̀rọ̀-àkọ́lé Tó Jẹ́ Mọ́ Ìtumọ̀ Pápá Nínú Iṣẹ́ àti Ìdásílẹ̀ Fún Àwọn Oniyanju Nlá

1. Gwandar

Da ake kawo aiki na gwamnatin kashi, tushen karamin, da kuma hanyoyin kashi mai yawa, an fi sani da darasi da kuma inganci na aiki na jihohin kashi. Wasu abubuwa masu aiki na tashin kafin gaba suna da muhimmanci a kan aiki na jihohin kashi. Amma wasu abubuwan da ake amfani da su ne suna da nasarorin wajen taimakawa waƙoƙi da aikin kashi mai yawa (kamar thermal, nuclear, da hydroelectric). Ana bukata a yi ɗaya daga cikin wurin da ba a iya taimaka, don in tabbatar da zimantakewa da ke aiki na jihohin kashi.

2. Duka Abubuwa Mai Yawa

Jihohin kashi mai yawa suna da duk abubuwan da za su iya ɗaukan waƙoƙi a kan aiki:

• ​Waƙoƙi na Stator Winding: Waƙoƙi na phase-to-phase short circuits, inter-turn short circuits, da ground faults. Inter-turn short circuits, hasen, suna da current mai yawa a farkon waƙoƙi, wanda ya ba shi da nasara a canza a bangaren transverse differential protection saboda cikakken wurin.
• ​Waƙoƙi na Rotor Circuit: Single-point ground faults, double-point ground faults, da open or short circuits na excitation circuit. Idan single-point ground fault ya ɗauka, ya kamata ake aiki ta hanyar, amma idan ya ɗauka zuwa double-point ground fault, zai iya haifar da magnetic asymmetry da kuma yanayin jihohin kashi mai yawa.
• ​Ayoyi Na Aiki Da Ba Daidai: Reverse power, loss of excitation, over-excitation, overvoltage, da frequency abnormalities. Idan ban da waƙoƙi mai yawa, wannan abubuwan suna da nasarorin wajen haifar da jihohin kashi ko kuma haifar da zimantakewa na grid.

3. Bayanin Aikin

Aikin da ake amfani da microprocessor-based protection solution ana yi a hierarchical distributed architecture. Tushen protection relay na farko ana yi aiki da hardware processing platform mai kyau da kuma alamar tashin kafin gaban da ya faru, kamar yadda aka bayyana:

3.1 Don Inter-Turn Short Circuits na Stator: Multi-Criteria Composite Protection

Don in taimaka waɗannan abubuwan da ake amfani da transverse differential protection da ba su iya taimaka waƙoƙi na inter-turn short circuits a kan phase na baya, wannan aikin ana amfani da multi-criteria fusion decision algorithm, wanda ya saukar da nasarorin taimakawa da kuma sensitivity.

• ​Muhimmanci Na Fanni:
• Negative-Sequence Power Direction Criterion: Ana tuntubi negative-sequence current da voltage a kan terminal na generator don in samun direction na negative-sequence power. Waƙoƙi na internal asymmetric (kamar inter-turn short circuits) suna haifar da negative-sequence source, wanda power direction ya zama mafi tsawo daga generator zuwa system, wanda ya taimaka waɗannan waƙoƙi na internal.
• Third Harmonic Voltage Variation Criterion: Ana tuntubi amplitude ratio da phase difference bayan neutral da terminal third harmonic voltages. Inter-turn short circuits suna haifar da pattern na distribution na third harmonic voltages, wanda wannan criterion ya taimaka da nasara.
• Neutral Point Displacement Voltage Criterion: Ana yi aiki a matsayin enhancement mai kyau don in saukar da nasarorin taimakawa.
• ​Abubuwan Da Su Da Kyau:
• Sensitivity Mai Yawa: Ana iya canza inter-turn short circuits da yake ɗaya 0.5%.
• Rapid Operation: Full operation time under 20 ms, wanda ya saukar da nasarorin waƙoƙi.
• Nasarorin Mai Yawa: Multiple criteria suna yi aiki ta hanyar interlock ko parallel don in taimaka waɗannan abubuwan da ba su iya taimaka.
• ​Case Study: Bayan a yi implementation a 500MW coal-fired generator, an samu 98% sensitivity a canza inter-turn short circuits, wanda ya taimaka waɗannan abubuwan da ba su iya taimaka.

3.2 Don 100% Stator Ground Fault Protection: Dual-Technology Fusion Positioning

Wasu abubuwan da ake amfani da fundamental zero-sequence voltage protection suna da wurin a kan neutral point. Wannan aikin ana amfani da biyu na teknologi mai yawa don in samun 100% protection coverage daga terminal zuwa neutral point.

• ​Muhimmanci Na Fanni:
• Conventional Zone (85–95%): Ana amfani da third harmonic voltage ratio method don in taimaka stator winding daga neutral point zuwa terminal.
• Blind Zone Compensation (Near Neutral Point, 5–15%): Ana amfani da injection-based stator ground fault protection. An injecte low-frequency (20Hz or 12.5Hz) voltage signal a rotor circuit, da kuma an tuntubi injection current don in samun insulation resistance da kuma location na waƙoƙi, wanda ya taimaka waɗannan abubuwan da ba su iya taimaka a kan neutral point.
• ​Abubuwan Da Su Da Kyau:
• 100% Coverage: Ba a da wurin, wanda ya taimaka full stator winding protection.
• Precise Localization: Ana canza location na ground fault da kyau don in taimaka maintenance.
• ​Case Study: A nuclear power plant, an samu ground fault a 3% from neutral point, da less than 1% error, wanda ya taimaka planned maintenance da kuma in taimaka unplanned outages.

3.3 Don Rotor Circuit Health: Dynamic Monitoring and Early Warning

Waƙoƙi na rotor circuit, kamar open rotating diodes, suna da nasarorin wajen haifar da waƙoƙi. Wannan aikin ana yi shift daga "post-fault protection" zuwa "pre-fault warning" a kan real-time monitoring.

• ​Muhimmanci Na Fanni:
• An fito high-frequency current transformers (CTs) ko dedicated monitoring modules a slip rings don in samun real-time excitation current waveforms.
• Built-in algorithms suna yi Fast Fourier Transform (FFT) harmonic analysis a kan current.
• Open rotating diodes suna haifar da distortion na excitation current waveform, wanda ya zama mafi characteristic harmonics (kamar fifth harmonic).
• ​Abubuwan Da Su Da Kyau:
• Early Warning: An yi alerts based on harmonic content exceeding thresholds (kamar fifth harmonic exceeding 8%), wanda ya taimaka maintenance checks a rotating rectifier bridge idan ba su iya taimaka.
• Prevention of Escalation: Timely warnings suna taimaka waɗannan abubuwan da ba su iya taimaka, kamar insulation damage da kuma rotor overheating.
• Condition-Based Maintenance: An bayyana data mai yawa don predictive maintenance.

4. Gwandar da Value

Wannan aikin na microprocessor-based protection ana amfani da advanced sensing technology, signal processing algorithms, da kuma multi-criteria intelligent decision-making don in taimaka waɗannan abubuwan da ba su iya taimaka a kan tashin kafin gaban da aikin kashi:

• An taimaka waɗannan abubuwan da ba su iya taimaka, wanda ya samun 100% coverage for stator inter-turn short circuits da ground faults.
• An yi shift daga post-fault protection zuwa pre-fault warning, wanda ya taimaka waɗannan abubuwan da ba su iya taimaka a kan dynamic rotor monitoring.
• An samu validation a kan real-world cases, wanda aikin ya taimaka high sensitivity, speed, da kuma reliability, wanda ya taimaka safety requirements na large and mega generators (500MW and above).