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"Adanya gangguan pada sistem tenaga listrik dapat memicu ketidakstabilan tegangan sistem. Ketidakstabilan tegangan sistem dapat menyebabkan runtuh tegangan yang kemudian berakhir dengan black out sebagian ataupun seluruh sistem. Sehingga penting untuk menjaga stabilitas tegangan sistem. Pada skripsi ini dibahas tentang analisis statis dan dinamis stabilitas tegangan sistem tenaga listrik CNOOC SES Ltd. dimana sistem menggunakan skema pelepasan beban undervoltage. Digunakan perangkat lunak ETAP 7.0.0 untuk simulasi aliran daya dan simulasi transient analysispada sistem. Metode kurva Q-V (analisis statis) digunakan sebagai pendekatan pada keadaan operasi normal dengan menggunakan simulasi aliran daya, sedangkan analisis dinamis digunakan pada simulasi transient analysis dengan mengatur lima skenario gangguan besar. Dengan metode kurva Q-V didapatkan bahwa bus beban pada daerah Utara rentan mengalami ketidakstabilan tegangan jika terjadi kenaikan/penambahan beban, sedangkan tegangan bus beban di daerah Selatan dan Tengah lebih stabil. Berdasarkan analisis dinamis, sistem tenaga listrik CNOOC SES Ltd. dapat mengembalikan stabilitas tegangannya setelah dilakukan pelepasan beban undervoltage dengan kapasitas yang berbeda dalam setiap skenario sehingga adanya skema pelepasan beban undervoltage sudah cukup efektif untuk mencegah terjadinya runtuh tegangan (voltage collapse).

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In a power system, disturbances can trigger into instability of system voltage. Instability of system voltage can lead to voltage collapse that ended with the partition or the whole system black out. So, it is important to maintain the system voltage stability. In this paper will be explained about static and dynamic analysis of CNOOC SES Ltd. voltage stability where the system uses undervoltage load shedding scheme. ETAP 7.0.0 software is used to simulate load flow and transient analysis to the system. Q-V curve method (static analysis) is used as an approach to the normal operation condition using load flow simulation, while dynamic analysis is used in transient analysis simulation by setting five large disturbance scenarios.

Using Q-V curve method, obtained that the load buses in the North Area are prone to voltage instability if there is an increase or addition of load, while the load buses in South and Central Area are more voltage stable. Based on dynamic analysis, CNOOC SES Ltd. power system can maintain the voltage stability after holding undervoltage load shedding for different load shedding capacity in each scenario, so the undervolatage load shedding scheme is effective enough to prevent voltage collapse."

"Dalam suatu perusahaan minyak dan gas, sistem tenaga listrik sangat berperan penting dalam proses pengolahan produksi. Oleh karena itu pada suatu sistem tenaga listrik dibutuhkan sistem proteksi yang baik. Salah satu gangguan yang sering terjadi pada suatu sistem tenaga listrik adalah gangguan beban berlebih. Pada skripsi ini akan dibahas mengenai suatu metode sistem proteksi untuk menanggulangi gangguan beban berlebih yang dikenal sebagai metode pelepasan beban dengan menggunakan rele frekuensi pada sistem tenaga listrik CNOOC SES Ltd. Gangguan berlebih yang terjadi adalah akibat lepasnya generator, dimana pada skripsi ini akan dibuat beberapa skenario kejadian lepasnya generator untuk melihat respon frekuensi sistem. Dengan melakukan metode pelepasan beban, diharapkan frekuensi sistem dapat kembali pulih ke frekuensi nominal dengan beban yang dilepaskan seminimal mungkin. Oleh sebab itu diperlukan pembuatan prioritas beban dan beberapa pengaturan pada rele frekuensi. Untuk membuktikan keefektifannya dilakukan simulasi menggunakan perangkat lunak ETAP 12.6.0 dengan sebelumnya melakukan pemodelan sistem tenaga listrik CNOOC SES Ltd. Dari hasil simulasi terbukti bahwa skema pelepasan beban yang dibuat berhasil memulihkan frekuensi sistem setelah terjadi gangguan dengan tahap pelepasan sesuai dengan yang diharapkan.

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In an oil and gas company, the power system plays an important role in the production process. Therefore, a power system required a good protection system. One of the most common disturbances in a power system is overloading. In this essay will be discussed about a method of protection system to overcome the overload known as the load shedding method by using under frequency relay on the power system of CNOOC SES Ltd. Overload that occurs is due to the trip fault of the generator, which in this essay will be made some scenarios of generator trip to see the response of frequency system.

By doing the load shedding method, it is expected that the system frequency can be recovered to the nominal frequency with the load that released is as minimum as possible. Therefore we need to make the priority of load and some settings on the under frequency relay. To prove the mehthod effectiveness, in this essay will be made some simulation using software ETAP 12.6.0 with previously modeling the power system of CNOOC SES Ltd. The simulation results proved that the load shedding scheme that is created successfully recover the frequency of the system after a disturbance with the shedding phase as expected."

"Gangguan dalam menghasilkan sistem tenaga listrik dapat menyebabkan ketidakstabilan tegangan pada sistem beban. Ketidakstabilan tegangan dalam sistem menyebabkan sistem beroperasi secara tidak normal yang menyebabkan keruntuhan tegangan atau pemadaman total di seluruh sistem. Makalah ini membahas analisis stabilitas tegangan statis dan dinamis dari Sistem Tenaga Senayan-Sambas dengan menggunakan perangkat lunak ETAP12.6.0 untuk simulasi aliran beban dan simulasi analisis sementara. Perubahan pengaruh persentase beban dan catu daya reaktif dari tegangan sistem akan diamati menggunakan analisis statis. Skema pelepasan beban dengan relai di bawah tegangan dan kompensator daya reaktif dalam beban, yang akan dilindungi ketika terjadi gangguan masif pada generator, akan digunakan sebagai sistem. Skema pelepasan beban disampaikan untuk mengembalikan dan menstabilkan tegangan sistem. Skema tersebut kemudian akan menjatuhkan beberapa beban prioritas tinggi dari sistem. 15 MVA atau 12,32% dari seluruh beban akan dihemat untuk mencegah beban dari tersandung kompensator daya reaktif yang digunakan dengan 30 capasitive rating MVAR.

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Interference in generating electric power systems can cause voltage instability in the load system. Voltage instability in the system causes the system to operate abnormally which causes a voltage collapse or a total blackout throughout the system. This paper discusses the static and dynamic stress stability analysis of the Senayan-Sambas Power System using ETAP12.6.0 software for load flow simulations and transient analysis simulations. Changes in the effect of the percentage load and reactive power supply of the system voltage will be observed using static analysis. A load release scheme with a relay under voltage and a reactive power compensator in the load, which will be protected when there is massive interference with the generator, will be used as a system. The load release scheme is delivered to restore and stabilize the system voltage. The scheme will then drop some high priority loads from the system. 15 MVA or 12.32% of the total load will be saved to prevent the load from tripping over the reactive power compensator used with 30 MVAR rating capacities."

"ABSTRAKAdanya gangguan pada sistem tenaga listrik dapat memicu terjadinya ketidakstabilan tegangan pada sistem. Ketidakstabilan tegangan pada sistem dapat menyebabkan sistem hilang kendali hingga tegangan tersebut runtuh, blackout atau mati total bisa terjadi pada keseluruhan sistem akibat runtuhnya tegangan tersebut. Pada skripsi ini dibahas tentang analisis statis dan dinamis stabilitas tegangan pada sistem tenaga listrik New TAL PT. Bukit Asam (Persero).Menggunakan perangkat lunak ETAP 12.6.0 untuk simulasi aliran daya dan transient analysis.Sistem menggunakan skema pelepasan beban dengan rele tegangan kurang (Under Voltage Relay).Metode kurva Q-V (analisis statis) digunakan untuk pendekatan keadaan operasi normal pada sistem dengan menggunakan simulasi aliran daya.Sedangkan, analisis dinamis menggunakan simulasi transient analysis dengan mengatur dua skenario gangguan besar.Dengan metode kurva Q-V didapatkan hanya terdapat satu bus beban yang dalam kondisi sangat rentan terhadap gangguan atau rapuh, yaitu area tambang dua. Pada kondisi tunak tegangan pada area tambang dua turun hingga 4,8%. Berdasarkan analisis dinamis, sistem tenaga listrik New TAL PT. Bukit Asam dapat mengembalikan stabilitas teganganya pada skenario pelepasan beban dengan mengggunakan rele tegangan kurang.Sistem pelepasan beban menggunakan rele tegangan kurangdapat menaikan tegangan jatuh hingga 3%.

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ABSTRACT

A disturbance in the power system can lead to voltage instability in the system. Voltage instability in the system can cause the system to lose control of the voltage collapse, or death total blackout could occur in the entire system due to the collapse of the voltage. In this paper discussed the analysis of static and dynamic voltage stability of the power system New TAL PT. Bukit Asam (Persero).

Using ETAP12.6.0 software for load flow simulation and transient analysis. System uses a load shedding scheme with UVR (Under Voltage Relay). Q-V curve method (static analysis) was used to approach normal operating state on the system by using the power flow simulation. On steady state voltage in area tambang dua was drop up to 4.8%.

Meanwhile, the dynamic analysis using transient simulation analysis by arranging two major disruption scenarios. Q-V curves obtained with the method there is only one bus load in conditions of extremely vulnerable to disruption or fragile, namely the mining area 2. Based on dynamic analysis, power system New TAL PT. Bukit Asam to restore the voltage stability by using a load shedding UVRscenario. Load shedding system using UVR were able to achieve 3% higher voltage rate after the distruption occur."

"Skripsi ini membahas tentang skema pelepasan beban menggunakan rele frekuensi pada sistem tenaga listrik CNOOC SES Ltd. yang mempunyai pembangkit listrik tenaga gas. Pelepasan beban dilakukan sebagai usaha memperbaiki kestabilan sistem yang terganggu karena beban lebih. Salah satu komponen stabilitas sistem yang mampu menjadi referensi pelepasan beban adalah frekuensi. Pelepasan beban diharapkan dapat memulihkan frekuensi dengan cepat dan jumlah beban yang dilepaskan seminimal mungkin. Oleh sebab itu diperlukan beberapa pengaturan pada rele frekuensi seperti waktu tunda rele, frekuensi kerja dan besar beban dilepaskan. Dengan menggunakan persamaan swing generator pada beberapa perhitungan, didapatkan nilai frekuensi kerja untuk rele frekuensi yang sesuai dengan sistem tenaga listrik CNOOC SES Ltd. dan nilai beban lepas yang paling efektif pada setiap tahap pelepasan beban. Untuk membuktikan keefektifan dari skema pelepasan beban, dibuatlah beberapa simulasi generator lepas yang menghasilkan ketidakseimbangan daya aktif antara daya yang dibangkitkan dan daya yang dibutuhkan beban dengan menggunakan ETAP 7.0. Dari simulasi, frekuensi sistem dapat pulih sekitar 3-9 detik setelah gangguan tergantung pada besar kelebihan beban pada sistem tenaga listrik.

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This undergraduate thesis discusses about load shedding scheme using under frequency relay in CNOOC SES Ltd. electric power system which have gas power plant. Load shedding is carried out as an effort to restore disturbed system stability because of overload condition.One of electric system stability components, which can be a reference for load shedding, is frequency. Load shedding is expected to restore generator frequency rapidly and the amount of load shed as minimum as possible. Therefore, it is needed under frequency relay setting such as relay time delay, frequency trip and percentage of released load. By using swing generator equation on some calculation, it is obtained the values of frequency for under frequency relay which is proper with the power system and the number of the most effective load shed in every load shedding scheme. To prove the effectiveness of the under frequency load shedding scheme, the undergraduate thesis makes some simulations about generators shed to make unbalance active power between generation disctrict and load district by using ETAP 7.0 software. From simulation, the system frequency is able to recover in 3 ? 9 seconds after disturbance depends on the magnitude of overload in the power system."

"Gangguan satu fasa ke tanah terjadi pada kabel bawah laut yang menghubungkan Pabelokan ke Nora. Gangguan ini seharusnya dapat segera diatasi oleh rele arus lebih pada penyulang Pabl – Nora dalam waktu 0,593 sekon. Akan tetapi, hal itu justru tidak terjadi dan malah menyebabkan seluruh area selatan, beberapa daerah area utara juga tengah mengalami pemadaman. Dalam skripsi ini, akan disimulasikan tiga kondisi arus gangguan yang berbeda – beda yaitu 397 A, 795 A dan 1,19 kA yang berasal dari kombinasi kontribusi arus gangguan oleh tiga generator yang bekerja. Ketidakseimbangan tegangan terjadi selama gangguan sehingga menyebabkan surge arrester pada G101B pecah. Kontribusi arus gangguan pun turun menjadi 397 A karena G101C memang tidak diaktifkan untuk bekerja. Nilai arus gangguan yang kecil ini membuat waktu tunda rele arus lebih IAC-53 pada feeder Pabelokan Nora beroperasi setelah 25 sekon. Nilai ini lebih lama daripada waktu yang dibutuhkan oleh rele SR489 untuk bekerja dengan nilai arus gangguan yang sama yaitu 8,31 sekon. Hal ini menyebabkan generator G101A lebih dahulu mengalami trip karena ground fault rele. Oleh karena itu, pengaturan nilai pick up arus gangguan dan waktu kerja rele pun harus diatur lebih cepat lagi yaitu pada kisaran 5 sekon untuk nilai arus yang sama agar kejadian serupa tidak terulang lagi.

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Phase to ground fault happened to the subsea cable that connected Pabelokan to Nora. This fault should be cleared by Over c urrent relay at Pabl- Nora feeder in 0,593 second. Nevertheless, it didn’t work that way instead it caused all the south area and some of central and north area was shutdown. There will be three conditions of fault current that will be simulated on this simulation which are 397 A, 795 A and 1,19 kA that is coming from the combination of three generators that worked. The unbalanced voltage that happened when fault is inserted caused surge arrester in G101B blown up. The current fault decreased and it was 397 A because G101C was not work from the first, due to repairement. The fault current value that is so small caused delay in IAC-53 reay at Pabl-Nora feeder. This rele worked after 25 seconds. This value is longer than the time that SR489 relay needed to work at the exactly same fault current that is 8,31 seconds. It is caused generator G101A tripped by ground fault relay. As the solution, pick up current and time delay setting must be set faster that is about 5 seconds for the same value of current fault so this kind of things is not going to happened again."

"Suatu Sistem tenaga listrik yang baik harus memiliki nilai tegangan yang tidak melebihi batas toleransi serta rugi-rugi daya yang kecil.Batas toleransi yang diperbolehkan untuk suatu nilai tegangan ± 5 - 10 % dari nilai nominalnya. Nilai tegangan yang konstan akan mengoptimalkan unjuk kerja dari peralatan listrik. Sedangkan rugi-rugi daya yang kecil akan menjaga pasokan daya listrik, serta dapat mengurangi kerugian finansial yang terjadi selama proses transmisi. Pada skripsi ini akan dilakukan perbaikan kualitas tegangan pada saluran transmisi antara Platform KARA yang WIDP pada perusahaan CNOOC SES Ltd. Dengan menggunakan trafo tap changer, penambahan beban kapasitif dan penambahan kabel saluran transmisi secara parallel. Proses perbaikan pada skripsi ini disimulasikan dengan menggunakan perangkat lunak ETAP 7.0.0. Dari hasil simulasi tersebut akan didapatkan perbaikan tegangan dan rugi-rugi daya yang paling optimal dan pada akhirnya dapat digunakan dalam proses perbaikan sesungguhnya.

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An electrical power system must have good voltage value that does not exceed the limits of tolerance and the power lossis small. Tolerance limit allowed for a rated voltage ± 5 - 10% of their nominal value. Constant voltage value will optimize the performance of electrical equipment. While the power lossis small will keep the supply of electrical power, and can reduce financial losses that occur during the transmission process.

At this skripsi will be improved quality of voltage on the transmission line between Platform KARA WIDP the company CNOOC SES Ltd. by using a transformer tap changer, the addition of capacitive load and the addition of parallel transmission line cables. Process improvement in the skripsi simulated using ETAP 7.0.0 software. From the simulation results will be obtained improved voltage and power loss is the most optimal and could ultimately be used in the actual repair process."

"The international recruitment and the employment of expatriates in host country and inpatriates in home country or outside the host country is one of the consequences of the open market policy of many countries. Buhler indicates that the international recruitment is perceived more because of the risk of an organization to compete globally that requires managers and leaders who have international experiences (Buhler 2002:100).With more countries opening themselves for foreign direct investment (FDI) there are more potential of employment of expatriates and inpatriates to provide among others the transfer of skills and technology (http:/lwww.unctad_org/templateslstartpage.asQ?intltem 17.00 hours, 26 June 2005). The transfer of skills and technology is very much a true important for an overseas oil and gas operation especially if the host country has no research and development facilities and thus is very much depending on the home country capabilities.Although Indonesia opens its door for foreign investors however the government has put some limitation to the employment of expatriates as part of their policies in safe guarding the employment of the local people. Foreign investors on the other hands, have three 3 major motives of employment of expatriates i.e. Staffing, due to skill and knowledge deficiencies, Management Development and Organizational Development (Harzing and Ruysseveldt 1995: 181-182).The purpose of this study is to analyze what factors, actors, objectives and alternative strategies of employment of expatriates and inpatriates at CNOOC (China National Offshore Oil Corporation) SES Ltd. CNOOC SES Ltd is one of the CNOOC Ltd subsidiaries operating an oil and gas concession in Indonesia. The employment of expatriates and inpatriates consist of employment of personnel from Parent/Home Country (PCN), Third Country National (TCN) and Host Country National (HCN). For the purpose of the study, Analytical Hierarchy Process (AHP) is used as the tool to analyze experts? judgments. The experts were chose from the Head Quarter in Beijing (2 experts), 3 experts from CNOOC SES Ltd, indonesia and 3 experts from the Government of Indonesia, in this case from BPMIGAS.One of the results from the study shows that staffing is the major objective in having expatriates working at the host country, with cost eftlciency as the prime factor for the employment of those expatriates while the Government of Indonesia, in this case BPMIGAS is the major actor in the decision making. lt is also noted that the Host Country National (HCN) would be the prime alternative of the employment of expatriates, if their competency matches with the competency possesses by the expatriate. The study also shows that the selection of inpatriates (personnel from host country working at head quarter or other countries than his/her own country) would be from personnel who are being employed by the company at the time of selection and is based on his/her competency while CNOOC SES Ltd as the primary decision maker with the objective to enhance the host country national competency (management development)."