Imam Djunaedi

Rotor-Dynamic Characteristic Evaluation of Generator Geothermal Power Plant Using Finite Element Method

Dynamic characteristics of a critical speed of the rotor components at generator geothermal power plant is evaluated using finite element method. In this study, the critical speed is evaluated based on the over speed scenario at 100%, 120% and 150% of rated speed. The critical speed of the rotor is investigated in the Campbell diagram, which shows the relationship between natural frequency and rotational velocity of the system. Based on the rotordynamic evaluation using finite element, the critical speed at 100% and 120% of the operating speed occurs in the rotational speed of 2750 and 2837 rpm, while at 150%, the critical rotation occurs in the rotational speed of 2750, 2762 and 4051 rpm. It can be concluded that the speed ranges are the critical speed or the resonance region which can be as a direct cause of the component damage, therefore the operating speed should not work too long on that critical speed.

Architecture and Engineering of Hydrogen Fuel Cell Power Generation Based on Renewable Energy

The paper presents an architecture and engineering of hydrogen fuel cell electric power generation system based on renewable energy that already installed in Tenjolaya village, Wanassalam sub-district, Lebak - Banten Province. It also discloses some important information as well as some valuable experiences from the pilot plant operation. The renewable electric power generation system combines wind turbine, photovoltaic, hydrogen electrolysis and fuel cell. The basic design of this system is focused on energy storage in the form of hydrogen gas that can be converted back into electricity by using fuel cell units. The engineering development was done to address the issues on limited energy storage in the battery unit which has several drawbacks i.e. short battery lifetime, limited storage capacity and rigorous and continuous maintenance schedule. To enable remote control and monitoring, a web based monitoring system was developed. From the monitoring system the following information are obtained: the amount of electrical power produced by the wind turbine that was intermittent and depends on time that reached 3000 W; similar pattern is observed from the output power of solar PVs and a maximum point of the solar cell power generation was 640 Watt; the time of electricity production by the wind turbine and the solar cell is complementary to each other in every one day cycle. Two valuable experiences have been gained those are: the location near sea shore has a very corrosive air that damages the wind turbine component, and the use of fuel cell requires high investment cost.

Remaining Life Assessment of the Generator Stator Insulation: A Case Study on Suralaya Coal Fired Power Plant in Indonesia

The failure of large generators in generating stations and industrial plants is mainly caused by the failure of the stator winding insulation. The combination of electrical, mechanical and thermal stresses that are accumulated by the number of start-stop times and operating hours can reduce the residual dielectric voltage as the main cause of the deterioration on the insulation. In this study, the remaining life assessment of the generator stator insulation was conducted based on the functional relationship between stresses and remaining dielectric voltage in the worst and average cases. The case study was conducted on the fourth of generator unit in SURALAYA Coal Fired Power Plant in Indonesia that had the service life of over 25 years. To validate the assessment results, partial discharges (PD) test was performed on the stator coils of the generator. Based on the results of evaluation, it was found that the remaining life of the fourth of generator insulation at the worst case had been come to end. For the average case, the remaining life of insulation for Unit 1 and Unit 2 was 12 year, while for Unit 3 and 4 was 17 year. Then from the validation results using the PD test, there was an evidence of the discharging of voids or delamination within the insulation, where the internal discharging was seen to be the most dominant factor from the discharge pattern. However, the PD magnitudes were still within reasonable limits, where the magnitude of the maximum discharge was 3,500 pC for the U phase, while in the V and W phase was 7000 pC, hence it was not categorized as an anomaly.

Magnetic Evaluation for Uprating 400 mW Coal Fired Generator

One of the considerations many power plants today is whether they can get more power out of their existing equipment especially generator. However, it is required design review and feasibility study in order to extend the operating life and increase the capability and reliability. In this study, analysis of magnetic field was performed due to power uprating in order to prevent a saturation of the magnetic field in the core laminate which can lead to the emergence of heat concentration. Based on the results of magnetic analysis using finite element, there are no saturation of the magnetic field in the core lamination which can lead to the magnetic saturation and heat concentration, both for existing and uprating conditions.Therefore, the increasing a design margin on the generators from the current design of the margin of 471,000 kVA to 494,550 kVA with the 0.85 power factor will not pose a problem as long as all of the following recommendations can be implemented. Although it is predicted, there will be no saturation and hotspots on the generator, but the risk of temperature rise due to the uprating should be reduced by replacing the stator winding using the Full Class F Insulation which is resistant to temperatures up to 155 °C.

Evaluation of Critical Speed of the Rotor Generator System Based on ANSYS

Critical speed rotor phenomenon characteristics at gas turbine generator is evaluated using finite element method. In this study, the critical speed is evaluated based on the over speed of 4500 rpm. The critical speed of the rotor is investigated in the Campbell diagram, which shows the relationship between natural frequency and rotational velocity of the system Dynamic characteristic in this paper simulated with ANSYS rotor dynamic software. The Finite Element simulation results will be known forms of vibration at each critical speed. Finally the results od simulation can be a reference for dynamic analysis and optimized the design of rotor generator.

Fitness for Service Assessment of High Pressure Heater Tube at Coal Fired Power Plant

The structural integrity of heat exchanger tube at high pressure heater of coal-fired power plant has been evaluated using fitness for service (FFS) assessment level 2 and 3. The purpose of this study isto determine the root cause of failure and the remaining life of components thereforethe possibility of failure due to improper design and operation can be known and it become a reference fordesigning a new design tubein a retubing process. Based on the evaluation results using level 2 assessment, the failureon the heat exchanger tubesisnotcaused bythe material creep becausethe total damage due to creep has been successfully met the requirements with the operating life3.873x109hours. However, base on the results of level 3 assessment using finite element, the minimum safety factor against yielding is below 1.0 and itdoesn’t meet the plastic collapse criterion, therefore the possibility of leakage failure on the tube is caused by the improper design which the construction of the tube is not able to withstand the operating load.