Analisis Stabilitas Transien Dan Mekanisme Pelepasan Beban Akibat Penambahan Pembangkit 1x26,8 MW Pada Sistem kelistrikan PT. Petrokimia Gresik

Sistem tenaga listrik akan beroperasi dalam keadaan stabil jika terdapat keseimbangan antara daya mekanik penggerak utama (prime mover) dengan keluaran daya listriknya. Setiap kenaikan atau penurunan beban harus diikuti dengan perubahan daya mekanik prime mover generator. Apabila tidak segera menyesuaikan maka akan membuat sistem menjadi tidak stabil. Kelebihan daya mekanik terhadap daya listrik mengakibatkan percepatan putaran generator atau sebaliknya. Bila gangguan tidak dihilangkan dengan segera, maka percepatan atau perlambatan putaran rotor generator akan menyebabkan hilangnya sinkronisasi pada generator sinkron. Pada PT. Petrokimia Gresik yang dijadikan plant tugas akhir ini, terdapat penambahan pembangkit dan beban baru sehingga perlu dilakukan studi stabilitas transien untuk mengetahui keandalan sistem saat terjadi gangguan transien serta mendapatkan skema Load Shedding yang baru karena kondisi sistem berbeda dengan sebelumnya. Pada tugas akhir ini difokuskan pada kestabilan transien meliputi respon frekuensi, sudut rotor, dan tegangan serta mekanisme pelepasan beban akibat hubung singkat, motor starting, dan generator lepas. Hasil simulasi menunjukkan bahwa lepasnya 1 generator memerlukan pelepasan beban untuk mengembalikan kestabilan sistem. Dalam kasus hubung singkat di bus, tegangan sistem turun hingga mencapai kondisi terendah sehingga diperlukan pengisolasian gangguan melalui pembukaan circuit breaker di sumber gangguan. Selain itu, kasus motor starting masih diperbolehkan saat kondisi 3 generator menyala. ========================================================================================================================Power system will operate in a stable condition if there is a balance between the power of mechanical prime mover and electric power output. Each increment or decrease the load must be followed with changes mechanical prime mover generator power. If it does not immediately adjust then would make the system become unstable. The advantages of mechanical power to electrical power can make the acceleration of the generator or vice versa. If the interference cannot be eliminated immediately, the acceleration or deceleration round rotor generator will cause a loss of synchronization at synchronous generator. At PT. Petrokimia Gresik which is used as this final project plant, there is addition of new generator and load so it is necessary to do study transient stability to know system reliability during transient disturbance and to get new Load Shedding scheme due to different system conditions than before. This final project is focused on transient stability include frequency, the angle of the rotor, and voltage response. Then mechanism load shedding due to a short circuit, motor starting, and the generator off. Simulation results show that the loss of one generator requires the release of the load to restore the stability of the system In the case of a short circuit in the bus, the system voltage drops to the lowest condition so that it is necessary to isolate the disturbance through the opening of the circuit breaker at the source of interference. In addition, cases of motor starting current conditions still allowed when 3 generator turned on