Aulia Siti Aisjah

Aplikasi Metode Neuro-Fuzzy Pada Sistem Pengendalian Antisurge Kompresor

The optimum operation condition of power system obtained from optimal calculation is determined without considering its dynamic stability limit. If the load of system is changed, power generating should accommodate the changes to make the demand of load supplied. This changing will shift dynamic stability system condition. This article deals with dynamic stability correction as a result of load of system changing by generation rescheduling using the biggest sensitivity of the sensitivity trajectory variable with respect to its parameters i.e. the power out put generators. The simulation in the 3-machines 9 bus power system with 25%, 50% and 75% load increasing of initial load caused eigen value position better, 1,2 and 3,4 of 25% load increasing each of them is 1,1 x 10-5 and 0,5 x 10-5, to 50% load increasing is 3,47 x 10-4 and 0,98 x 10-4, to 75% load increasing is 1,11 x 10-4 and 1,67 x 10-4 more far from imaginary axis compare to before generating rescheduling. The simulation result with this method indicates that there is dynamic stability correction, in this manner the system operates with better dynamic stability condition. Abstract in Bahasa Indonesia : Kondisi operasi optimum sistem tenaga yang diperoleh dari perhitungan optimasi dilakukan tanpa memasukkan batas stabilitas dinamiknya. Jika terjadi perubahan pada beban maka pembangkitan daya harus menyesuaikan perubahan tersebut agar tetap memenuhi kebutuhan beban. Perubahan pembangkitan akan mengubah kondisi stabilitas dinamik sistem. Makalah ini membahas tentang perbaikan stabilitas dinamik akibat perubahan beban sistem melalui penjadwalan ulang pembangkit menggunakan sensitivitas terbesar dari sensitivitas trayektori variabel keadaan sistem yaitu sudut rotor relatif terhadap parameternya yaitu daya output generator. Pengujian pada sistem tenaga 3-mesin 9-bus dengan kenaikkan beban 25%, 50% dan 75% dari beban dasar menyebabkan letak nilai eigen terkait lebih baik, 1,2 dan 3,4 untuk kenaikkan beban 25% masing-masing adalah 1,1 x 10-5 dan 0,5 x 10-5, untuk kenaikkan beban 50% adalah 3,47 x 10-4 dan 0,98 x 10-4, untuk kenaikkan beban 75% adalah 1,11 x 10-4 dan 1,67 x 10-4 lebih jauh dari sumbu imajiner dibandingkan sebelum penjadwalan ulang pembangkit. Hasil pengujian dengan metode ini menunjukkan adanya perbaikan stabilitas dinamik, sehingga sistem tenaga beroperasi dengan kondisi stabilitas dinamik yang lebih baik. Kata kunci: stabilitas dinamik, penjadwalan ulang pembangkit, perhitungan optimasi, dan sensitivitas trayektori.

Parameter Estimation of Maneuvering Variables of SIGMA-Extended War Ship Using Kalman Filter

SIGMA-class warship one of warship type is designed up to sea state 6. The ship was redesigned in enlarged dimensions, and called SIGMA extended class warships. A control system can give a performance of response in accordance to the set point when the value of controlled variable can be transmitted to the controller accurately. The characteristic of sensor is not usually able to tranmit a proper value, due to the noise on the sensor and also the environment disturbances. This paper describe a strategy of Kalman filter to estimate variables controlled when the presence noise on the compass or gyrocompas. The result of Kalman filter implementations give the magnitude of the integral absolute error of yaw and sway less than 5%, when there are noise on the measurement and the disturbances.

Analysis of The Dynamic Stability Positioning Control System of Semisubmersible

The semisubmersible offshore dynamics depend on the condition of the ocean environments. Disruption of forces and moments in the floating structure caused by environment factors, there are wind, waves and ocean currents. This disturbances will cause decreased stability of the structure. This situation will disrupt the process of oil and gas exploration. Currently exploration activities is success if the structure in the static condition and remain on. This condition needs a force or torque to counter the disruption caused by the environment. This paper proposes a control system and analyze the performance of response stability of dynamic positioning system (DPS). DPS will control in 3 Degree of Freedom (DOF) variables, there are: sway, roll and yaw. The structure of the DPS consists of controllers, sensors, actuators. Actuators are Thruster System and Power System. The strategic to maintain in DPS is Linear Quadratic (LQG) control. This method is one of optimal control which capable rejected wave interference. Some values control parameters, that are Q and R in the cost function, show the robustness of DPS.

Sverdruv Munk Bretschneider Modification (SMB) for Significant Wave Height Prediction in Java Sea

Sverdruv Munk Bretschneider (SMB) methods is a semi-empirical method that has been used for the prediction of the significant wave height – Hs in global watersheds. Indonesian waters are surrounded by thousands of islands and wind movement has different nature with the waters of free movement. Java sea is flanked by the waters of Java and Borneo island. Sea breeze movement in Indonesia as a result of changes in atmospheric pressure in Asia and Australia. SMB methods require modification in the waters of Indonesia, so as to be used as a predictor in accordance with the high degree of accuracy. In this paper, a propose methods of designing the predictor with a modified SMB. The method compared by numerical methods of Nonlinear Autoregressive Exogeneous (NLARX) and expertise method of Artificial Neural Network (ANN). Case studies conducted in the Java sea along Surabaya – Banjarmasin cruises. This line is a busiest sea transportation in Indonesia. The data obtained from Badan Meteorologi, Klimatologi dan Geofisika (BMKG), the agency of meteorology, climatology and geophysics in Indonesia. The data are the wind speed and significant wave height. The length of data in interval 6 years, since 2006 until 2011. Predictor results shows a Root Mean Square Error RMSE of modified SMB is 0.05, while NLARX method and ANN respectively are 0.24 and 0.16. Original Research Article Aisjah et al.; BJAST, 16(2): 1-8, 2016; Article no.BJAST.19669 2

Maritime weather prediction using fuzzy logic in java sea

Fuzzy logic has mostly been used in different kind of field either in taking decision, or control system and forecasting. Fuzzy logic is one that can represent a complex situation into a simple form in a language that is easily caught by humans. Similarly, to represent the nature of weather easily understood by ordinary people, this is the result of weather forecasting based on meteorological data. Some of the statistical methods used for weather forecasting are Auto Regressive (AR), Integrated Moving Average (ARIMA) and found some shortcomings of these traditional method. That is the need for historical data is not small, low-prediction accuracy results in a complex condition. This paper describes the strategy in weather forecasting based on fuzzy logic for maritime weather. Case studies conducted in the Java Sea, cruise lines Surabaya- Banjarmasin. The results showed that the level of accuracy prediction for 86.64% of the Java Sea, and prediction accuracy decreased for the next 24 hours ahead. Predictors of ability to demonstrate the ability to detect anomalous high sea waves in the waters of the Java Sea