Analisa Kestabilan Sistem Kendali Eksitasi Generator Tipe Arus Searah Tanpa dan dengan Pengendali Berdasarkan Pendekatan Tanggapan Frekuensi

This journal discussed the stability analysis of generator excitation control system in type of direct current without and by using controller. The stability Analysis was conducted on absolute stability analysis, relative stability analysis and internal stability analysis. For the absolute stability analysis was demonstrated by using gain margin and phase margin value. In order to get satisfied system performance so that cultivated gain margin value was greater than 6 dB and phase margin value was in ranges from 30⁰ to 60⁰. For the relative stability was shown by the peak value of resonance. The system would be relatively stable if the peak value of resonance range was between 1:10 to 1:50. The system would be internal stable if all closed circle transfer functions from input to internal output was stable. For internal stability indicator was shown by number 0 if the system is internally stable and number 1 if the system was internally unstable. For controllers used consisted of Proportional controller (P), Proportional Integral controller (PI), Proportional Differential controller (PD) and Proportional Integral Differential controller (PID). The controllers were designed with a frequency response approach. The results showed that the voltage response of generator excitation system type direct current with Proportional controller (P), Proportional Integral controller (PI), Proportional Differential controller (PD) and Proportional Integral Differential controller (PID) was stable of absolute, relative and internal.

With Proportional controller (P), the voltage response of generator excitation system type direct current had 4.2542 (12.5760 dB) in gain margin value, 50.5290 degrees in phase margin value, 1.2136 (1.6816) in resonance peak value and 0 in internal stability index. With Proportional Integral controller (PI), the voltage response of generator excitation system type direct current had 4.3362 (12.7420 dB) in gain margin value, 49.0000 degrees in phase margin value, 1.2391 (1.8624 dB) in resonance peak value and 0 in internal stability index. With Proportional Differential controller (PD), the voltage response of generator excitation system type direct current had 16.6910 (24.4490 dB)in gain margin value, 54.0000 degrees in phase margin value, 1.1030 (0.8516 dB)  in resonance peak value and 0 in internal stability index. For Proportional Integral Differential controller (PID), the voltage response of generator excitation system type direct current had 8.9451 (19.0320 dB) in gain margin value, 50.0000 degrees in phase margin value, 1.1792 (1.4316 dB) in resonance peak value and 0 in internal stability index.

Keyword: Excitation system, absolute stability, relative stability, internal stability, frequency response

Abstrak— Jurnal ini membahas tentang analisa kestabilan sistem kendali eksitasi generator tipe arus searah tanpa dan dengan pengendali. Analisa kestabilan yang dilakukan meliputi analisa kestabilan mutlak, analisa kestabilan relatif dan analisa kestabilan internal. Untuk analisa kestabilan mutlak ditunjukkan dengan menggunakan nilai margin penguatan dan nilai margin fasa. agar performansi sistem memuaskan maka diusahakan nilai margin penguatan ini besar dari 6 dB dan nilai margin fasa berkisar antara 30⁰ sampai 60⁰. Untuk kestabilan relatif ditunjukkan dengan nilai puncak resonansi. Sistem akan bersifat stabil relatif jika nilai puncak resonansi berkisar antara  1.10  s/d 1.50. sistem akan bersifat stabil internal jika semua fungsi alih lingkar tertutup dari masukan ke keluaran internal bersifat stabil.  Untuk indikator kestabilan internal ini ditunjukkan oleh angka 0 jika sistem bersifat stabil internal dan angka 1 jika sistem bersifat tidak stabil internal. Untuk pengendali yang digunakan terdiri dari pengendali Proporsional (P), pengendali Proporsional Integral (PI), pengendali Proporsional Diferensial (PD) dan pengendali Proporsional Integral Diferensial (PID). Pengendali – pengendali tersebut dirancang dengan pendekatan tanggapan frekuensi. Hasil yang diperoleh bahwa tanggapan tegangan sistem eksitasi generator tipe arus searah dengan pengendali Proporsional (P), pengendali Proporsional Integral (PI), pengendali Proporsional Diferensial (PD) dan pengendali Proporsional Integral Diferensial (PID) bersifat stabil mutlak, stabil relatif dan stabil internal.

Dengan kontroler Proporsional (P), respon tegangan generator eksitasi jenis sistem arus searah memiliki 4,2542 (12,5760 dB) nilai marjin keuntungan, 50,5290 derajat nilai fasa, 1,2136 (1,6816) dalam resonansi nilai puncak dan 0 dalam indeks stabilitas internal. Dengan kontroler Proportional Integral (PI), respon tegangan dari jenis sistem eksitasi generator arus searah memiliki 4,3362 (12,7420 dB) nilai marjin keuntungan, 49,0000 derajat nilai fasa, 1,2391 (1,8624 dB) di resonansi nilai puncak dan 0 dalam stabilitas internal yang indeks. Dengan kontroler Proporsional Differential (PD), respon tegangan dari jenis sistem eksitasi generator arus searah memiliki 16,6910 (24,4490 dB) nilai marjin keuntungan, 54,0000 derajat nilai fasa, 1,1030 (0,8516 dB) di resonansi nilai puncak dan 0 dalam stabilitas internal yang indeks. Untuk Proporsional Integral Diferensial controller (PID), respon tegangan dari jenis sistem eksitasi generator arus searah memiliki 8,9451 (19,0320 dB) nilai margin keuntungan, 50,0000 derajat nilai fasa, 1,1792 (1,4316 dB) di resonansi nilai puncak dan 0 di intern indeks stabilitas.

Kata kunci :  sistem eksitasi, kestabilan mutlak, kestabilan relatif, kestabilan internal, tanggapan frekuensi