Implementasi Dan Evaluasi Kinerja Skema Under Frequency Load Shedding (UFLS) Berbasis Fast Voltage Stability Index (FVSI) Pada Sistem Kelistrikan Sumatera

Rafli, Ferdial (2026) Implementasi Dan Evaluasi Kinerja Skema Under Frequency Load Shedding (UFLS) Berbasis Fast Voltage Stability Index (FVSI) Pada Sistem Kelistrikan Sumatera. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sistem Kelistrikan Sumatera merupakan sistem tenaga listrik interkoneksi berskala besar yang menghubungkan berbagai pusat pembangkit dan pusat beban di Pulau Sumatera. Kompleksitas jaringan serta tingginya ketergantungan antarwilayah menyebabkan sistem rentan terhadap gangguan besar, khususnya kehilangan pembangkit secara tiba-tiba yang dapat mengakibatkan ketidakseimbangan daya aktif dan penurunan frekuensi sistem. Untuk mencegah terjadinya pemadaman meluas (blackout), skema Under Frequency Load shedding (UFLS) diterapkan sebagai mekanisme pertahanan sistem dengan melepaskan sebagian beban secara bertahap ketika frekuensi turun di bawah batas yang telah ditentukan. Namun, skema UFLS konvensional umumnya hanya mempertimbangkan parameter frekuensi tanpa memperhatikan kondisi kestabilan tegangan pada lokasi beban yang dilepaskan, sehingga efektivitas pelepasan beban dalam memulihkan kestabilan sistem belum optimal. Penelitian ini mengusulkan penerapan skema UFLS berbasis Fast Voltage Stability Index (FVSI) pada Sistem Kelistrikan Sumatera. Metode yang digunakan diawali dengan analisis aliran daya untuk memperoleh kondisi operasi sistem pada saat beban puncak. Selanjutnya, nilai FVSI dihitung pada setiap saluran transmisi dan diakumulasikan menjadi indeks kestabilan tegangan pada bus beban (FVSI bus). Berdasarkan nilai tersebut, sistem dibagi menjadi tiga zona prioritas dan beban yang akan dilepaskan ditentukan berdasarkan tingkat kerawanan tegangan masing-masing zona. Kinerja metode yang diusulkan dievaluasi melalui simulasi dinamik menggunakan DIgSILENT PowerFactory pada lima skenario gangguan berupa kehilangan beberapa unit pembangkit besar secara simultan. Hasil simulasi dibandingkan dengan skema UFLS eksisting yang saat ini diterapkan pada Sistem Kelistrikan Sumatera.
Hasil penelitian menunjukkan bahwa penerapan UFLS berbasis FVSI mampu meningkatkan efektivitas pelepasan beban dengan mengarahkan proses load shedding pada area yang memiliki tingkat kestabilan tegangan lebih rendah. Dibandingkan dengan skema eksisting, metode yang diusulkan mampu mengurangi kebutuhan pelepasan beban sebesar 6,47% hingga 10,93% pada Luar Waktu Beban Puncak (LWB) dan 7,72% hingga 12,11% pada Waktu Beban Puncak (WBP) dengan tetap mempertahankan kinerja pemulihan frekuensi sistem. Dari semua skenario yang diuji, Skenario 2 memberikan performa terbaik dengan menghasilkan frekuensi nadir yang lebih baik, frekuensi keadaan tunak yang lebih mendekati frekuensi nominal, serta tidak menimbulkan kondisi over-frequency setelah proses pelepasan beban. Hasil penelitian menunjukkan bahwa integrasi FVSI dalam skema UFLS dapat meningkatkan keandalan dan ketahanan Sistem Kelistrikan Sumatera terhadap gangguan besar melalui strategi pelepasan beban yang lebih adaptif dan berbasis kondisi sistem.
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The Sumatra Power System is a large-scale interconnected power network that links numerous generation units and load centers across Sumatra Island. The complexity of the network and the strong interdependence among regions make the system vulnerable to major disturbances, particularly the sudden loss of generating units, which may result in active power imbalance and severe frequency decline. To prevent widespread blackouts, Under-Frequency Load shedding (UFLS) is commonly employed as a system defense scheme by disconnecting loads in stages when the system frequency falls below predefined thresholds. However, conventional UFLS schemes are generally designed based solely on frequency criteria and do not consider the voltage stability conditions of the load locations to be disconnected, which may limit the effectiveness of system recovery.
This paper proposes an FVSI-based Under-Frequency Load shedding (UFLS) scheme for the Sumatra Power System. The proposed approach begins with steady-state power flow analysis under peak load conditions. The Fast Voltage Stability Index (FVSI) is then calculated for each transmission line and aggregated into a bus-based voltage stability index (bus FVSI). Based on the obtained FVSI values, the system is divided into three priority zones, and the load shedding locations are determined according to the voltage vulnerability level of each zone. The performance of the proposed method is evaluated through dynamic simulations in DIgSILENT PowerFactory under five disturbance Skenarios involving the simultaneous outage of several large generating units. The results are compared with the existing UFLS scheme currently implemented in the Sumatra Power System.
The simulation results demonstrate that the proposed FVSI-based UFLS scheme improves the effectiveness of load shedding by prioritizing areas with lower voltage stability margins. Compared with the existing scheme, the proposed method reduces the amount of load shedding by 6.47%–10.93% during Off-Peak Load (OPL) conditions and by 7.72%–12.11% during Peak Load (PL) conditions while maintaining satisfactory frequency recovery performance. Among all tested Skenarios, Skenario 2 exhibits the best performance, providing a higher frequency nadir, a steady-state frequency closer to the nominal value, and no over-frequency condition after load shedding. These results demonstrate that integrating FVSI into the UFLS scheme can significantly enhance the reliability and frequency resilience of the Sumatra Power System through a more adaptive and system-condition-based load shedding strategy.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Under Frequency Load shedding (UFLS), Fast Voltage Stability Index (FVSI), defense scheme, Sistem Kelistrikan Sumatera Under Frequency Load shedding (UFLS), Fast Voltage Stability Index (FVSI), defense scheme, Sumatera power system
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK201 Electric Power Transmission
Divisions:	Faculty of Electrical Technology > Electrical Engineering > 20101-(S2) Master Thesis
Depositing User:	Ferdial Rafli
Date Deposited:	30 Jul 2026 07:38
Last Modified:	30 Jul 2026 07:38
URI:	http://repository.its.ac.id/id/eprint/139912

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