Electronic Theses and Dissertation

Integrasi distributed generation (DG) pada sistem distribusi menyebabkan
perubahan arah aliran daya dan besaran arus hubung singkat pada skema operasi
on-grid dan off-grid yang berpotensi menimbulkan kesalahan operasi pada over
current relay (OCR) dengan setting tetap. Penelitian ini mendesain adaptive over
current relay (AOCR) yang mampu menyesuaikan nilai arus pickup dan time dial
setting (TDS) secara real-time berdasarkan kondisi arus beban dan arus hubung
singkat sistem. Metode yang digunakan meliputi pemodelan sistem distribusi 14
bus terintegrasi DG, simulasi aliran daya untuk memperoleh variasi arus beban dan
simulasi gangguan hubung singkat tiga fasa pada kedua mode operasi
menggunakan MATLAB/Simulink. Parameter arus pickup ditentukan berdasarkan
arus beban maksimum dengan margin pengaman, sedangkan TDS dihitung
berdasarkan rasio arus gangguan terhadap arus pickup sesuai karakteristik inverse
time. Hasil penelitian menunjukkan perubahan skema operasi menyebabkan
perbedaan arus beban dan arus hubung singkat sehingga parameter proteksi
menyesuaikan secara real time pada setiap line. AOCR mampu menyesuaikan nilai
arus pickup, Plug Setting Multiplier (PSM), TDS, dan waktu operasi relay secara
otomatis sesuai kondisi sistem. Pada skema on-grid diperoleh waktu operasi relay
berkisar antara 0,0355–0,2178 s, sedangkan pada skema off-grid berkisar antara
0,0355–0,7878 s. Hasil tersebut menunjukkan bahwa AOCR mampu
mempertahankan sensitivitas proteksi pada sistem distribusi yang beroperasi dalam
skema on-grid atau off-grid tanpa memerlukan pengaturan ulang setting relay
secara manual.

The integration of distributed generation (DG) into distribution systems causes changes in power flow direction and short-circuit current magnitude under on-grid and off-grid operating schemes, which may lead to the malfunction of overcurrent relays (OCRs) with fixed settings. This study designs an Adaptive Overcurrent Relay (AOCR) capable of adjusting the pickup current and time dial setting (TDS) values in real time based on the system load current and short-circuit current conditions. The proposed method includes modeling a 14-bus distribution system integrated with DG, performing power flow simulations to obtain load current variations, and conducting three-phase short-circuit fault simulations under both operating modes using MATLAB/Simulink. The pickup current parameter is determined based on the maximum load current with an appropriate safety margin, while the TDS is calculated according to the ratio of fault current to pickup current in accordance with the inverse-time characteristic. The results show that changes in the operating scheme cause variations in load current and short-circuit current, allowing the protection parameters to adapt in real time for each distribution line. The AOCR is capable of automatically adjusting the pickup current, Plug Setting Multiplier (PSM), TDS, and relay operating time according to the system operating conditions. Under the on-grid operating scheme, the relay operating time ranges from 0.0355 to 0.2178 s, whereas under the off-grid operating scheme, it ranges from 0.0355 to 0.7878 s. These results demonstrate that the AOCR is capable of maintaining protection sensitivity in distribution systems operating under either on grid or off-grid schemes without requiring manual readjustment of relay settings.