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Abstrak :
In electric power systems that consist of some generators, electric power stability in supplies side becomes the most important problems, which must be paid attention. In the interconnection system, if there are some troubles in transmission, generator or load will cause another generators feel the existence of instability condition. For instability condition which not too serious, system can overcome the fault and will not influence stability of system as a whole. However, for in big scale of fault and happened in a long duration can be ejected system becoming unstable and will result hampered of electrics energy supply to the load For the worst condition could be blackout condition. This article studies about improvement of the stability of the system by using excitation current and the prime mover of generators, which is coordinated fuzzy logic control in synchronize generator. By using annexation from three methods above, the condition of stability of the power system can attain the stability. The transient stability needed control in order that system with good stability can return to normal condition. Faulted electric power system often caused by failure in controlling the transient stability. It is because in transient stability forms critical condition for electrical power system. By controlling the level of excitation current and mechanical energy from the prime mover of generators which controlled by fuzzy logic when the fault is happened will make acceleration area become decreasing and deceleration area become increasing with the result that system can be stable quickly. It visible that from result of simulation obtained if using generator oscillation of fuzzy logic control, transient period becoming shorter and amplitude of oscillation wave is smaller compare by using without fuzzy logic. Likewise, this method is able loo to overcome transient condition at starting period of a generator.

Abstrak :

Penelitian ini menawarkan pengujian dan evaluasi dari pengaplikasian pengendali nonlinear model predictive control (NMPC) konvensional dan economic NMPC (E-NMPC) pada sistem reaktor biokimia dengan laju pertumbuhan monod dan penghambat substrat. Tujuan utama pengendalian dengan NMPC adalah optimisasi teknis yaitu dengan meminimalisir deviasi dari nilai konsentrasi biomassa dalam reaktor dengan nilai yang diinginkan. Selain itu, tujuan utama pengendalian dengan E-NMPC adalah optimisasi ekonomi dengan mengoptimisasi produksi biomassa yang dihasilkan reaktor. Variabel yang dikendalikan (CV) adalah konsentrasi biomassa dalam reaktor, sedangkan variabel yang dimanipulasi (MV) yang juga menjadi variabel keputusan pada komponen optimisasi pengendali adalah laju dilusi. Dilakukan identifikasi sistem serta formulasi algoritma dan optimisasi pengendali E-NMPC. Penyetelan pengendali NMPC dan E-NMPC dilakukan dengan fine tuning terhadap parameter-parameter tuning pengendali. Pengendali yang telah disetel disimulasikan pada perangkat lunak optimisasi paralel dengan fine tuning dari pengendali E-NMPC. Untuk menguji performa pengendali, diberikan gangguan step pada konsentrasi substrat umpan untuk mengamati respon pengendali terhadap gangguan tersebut. Parameter utama yang akan dievaluasi untuk meninjau kinerja pengendali adalah besar fungsi objektif ekonomi. Disamping itu, ditinjau juga profil MV, ISE dari CV, serta waktu komputasi pengendali. Hasil simulasi menunjukkan bahwa skema pengendalian dengan NMPC konvensional mampu menjaga dan mengubah CV ke nilai yang diinginkan. Selain itu, skema pengendalian dengan E-NMPC memiliki produktivitas berupa produksi kumulatif biomassa yang lebih tinggi daripada skema pengendalian dengan NMPC konvensional, namun memiliki waktu komputasi yang jauh lebih lama.

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This research proposes an examination and evaluation on the application of conventional nonlinear model predictive control (NMPC) and economic NMPC on biochemical reactor system with monod and substrate inhibition growth kinetics. The NMPC controller’s main objective is technical optimization which minimizes the controlled variable deviation from a desired set point, whereas the E-NMPC controller’s main objective is economical optimization which maximizes the cumulative biomass production of the reactor. The controlled variable for this research is the biomass concentration insisde the reactor, whereas the manipulated variable, which also acts as a decision variable for controller optimization, is the dilution rate. Identification of the system is initially done along with formulation of the control algorithm and optimization problem statement for the E-NMPC controller. Tuning of the conventional NMPC and E-NMPC controller is done by fine tuning of the tuning parameters. A step disturbance of feed substrate concentration is used to test the controllers‘ performance. Main evaluation of the controllers‘ performance will be based on economic cost function. Other parameters that will be evaluated are the MV profile, ISE of the CV, and controllers‘ computation time. Result shows that the conventional NMPC schemes are able to bring or maintain the controlled variable to a desired set point. However, the ENMPC scheme outperform the conventional NMPC in cumulative biomass production along the simulation period at the cost of higher computational time.