Evaluasi Sistem Proteksi Generator Turbin Uap 2X315MW Pada PT PLN Nusantara Power Rembang

Kanti, Diayu (2026) Evaluasi Sistem Proteksi Generator Turbin Uap 2X315MW Pada PT PLN Nusantara Power Rembang. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Keandalan operasional Pembangkit Listrik Tenaga Uap (PLTU) sangat bergantung pada kinerja sistem proteksi dalam melindungi generator, transformator, dan peralatan pendukung dari gangguan internal maupun eksternal. PT PLN Nusantara Power Unit Pembangkit Rembang merupakan PLTU dengan kapasitas terpasang 2×315 MW yang menyuplai listrik ke wilayah Rembang dan sekitarnya melalui jaringan 150 kV. Insiden trip Unit 1 akibat maloperasi relai diferensial menyeluruh (87O) yang dipicu oleh sympathetic inrush current saat energizing transformator utama Unit 2 menjadi latar belakang evaluasi ini. Kejadian ini terjadi sebagai akibat dari kombinasi beberapa fator yakni saturasi CT transien yang tidak seragam akibat perbedaan rasio CT yang signifikan (2000/5, 2500/5, dan 15000/5), keterbatasan manufaktur relai dalam penyesuaian matching factor pada sisi HV UAT menyebabkan arus diferensial yang terbaca menjadi lebih besar dari nilai sebenarnya, serta pengaturan slope yang terlalu rendah untuk mengakomodir kondisi tersebut. Selain itu tidak aktifnya fitur harmonic blocking karena kandungan harmonisa kedua pada sympathetic inrush berada di bawah threshold 10% sehingga relai tidak dapat mengenali arus tersebut sebagai arus inrush, dibuktikan dengan kondisi yang tercatat pada disturbance record. Evaluasi dilakukan terhadap dua belas fungsi relai yang terdiri dari proteksi generator dan relai diferensial generator-transformator menggunakan simulasi aliran daya dan hubung singkat pada ETAP 19 serta analisis pengaturan relai melalui Microsoft Excel, mengacu pada IEEE Std C37.102-2023 dan IEEE Std C37.91-2021. Hasil evaluasi menunjukkan tujuh relai memerlukan rekomendasi pengaturan, yaitu relai diferensial menyeluruh (87O), eksitasi berlebih (24), tegangan rendah dan berlebih (27/59), daya terbalik (32R), frekuensi rendah dan berlebih (81U dan 81O), arus lebih urutan negatif (46), dan beban berlebih termal (49S). Lima relai lainnya, yaitu relai diferensial generator (87G), hilang medan (40), gangguan tanah stator (64S), arus lebih kendali tegangan (51V), dan hilang sinkronisasi (78), dinyatakan sudah sesuai standar yang berlaku.
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The operational reliability of a Steam Power Plant (PLTU) heavily depends on the performance of its protection system in safeguarding the generator, transformer, and supporting equipment from both internal and external disturbances. PT PLN Nusantara Power Rembang Generation Unit is a 2×315 MW coal-fired power plant that supplies electricity to the Rembang region and its surroundings through a 150 kV network. The background of this evaluation is an incident in which Unit 1 tripped due to maloperation of the overall differential relay (87O), triggered by a sympathetic inrush current during the energization of the Unit 2 main transformer. This incident occurred as a result of a combination of several factors, namely non-uniform transient CT saturation caused by significant differences in CT ratios (2000/5, 2500/5, and 15000/5), manufacturer limitations of the relay in adjusting the matching factor on the HV side of the UAT, which caused the measured differential current to appear larger than its actual value, as well as a slope setting that was too low to accommodate such conditions. In addition, the harmonic blocking feature was not activated because the second harmonic content in the sympathetic inrush current was below the 10% threshold, preventing the relay from recognizing the current as an inrush current, as evidenced by the conditions recorded in the disturbance record. The evaluation was conducted on twelve relay functions comprising generator protection and generator-transformer differential protection using load flow and short-circuit simulations in ETAP 19, along with relay setting analysis through Microsoft Excel, in accordance with IEEE Std C37.102-2023 and IEEE Std C37.91-2021. The evaluation results indicate that seven relays require setting adjustments: the overall differential relay (87O), overexcitation relay (24), under/overvoltage relays (27/59), reverse power relay (32R), under/overfrequency relays (81U and 81O), negative sequence overcurrent relay (46), and stator thermal overload relay (49S). The remaining five relays generator differential relay (87G), loss of field relay (40), stator ground fault relay (64S), voltage-controlled overcurrent relay (51V), and out-of-step relay (78) were found to comply with the applicable standards.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Pembangkit, Relai, Sympathetic Inrush, Saturasi CT, Maloperasi Power Plant, Relay, Sympathetic Inrush, CT Saturation, Maloperation
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK2861 Electric relays. Protective relays--Security measures.
Divisions:	Faculty of Intelligent Electrical and Informatics Technology (ELECTICS) > Electrical Engineering > 20201-(S1) Undergraduate Thesis
Depositing User:	Diayu Kanti
Date Deposited:	21 Jul 2026 09:32
Last Modified:	21 Jul 2026 09:32
URI:	http://repository.its.ac.id/id/eprint/136016

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