Simulasi Rancang Bangun Gridside Converter pada Double Fed Induction Generator Menggunakan Fuzzy Logic

Pada zaman di mana energi terbarukan sudah mulai banyak digunakan, pembangkit listrik pun juga mulai beralih ke pembangkit dengan sumber energi yang terbarukan dan lebih ramah lingkungan. Salah satu sumber energi terbarukan yang biasa digunakan pada pembangkit listrik adalah angin. Doubly Fed Induction Generator (DFIG) merupakan sistem pembangkit tenaga angin yang dapat mengubah tenaga kinetik menjadi tenaga listrik. Pada penerapan DFIG permasalahan yang ditemui adalah tegangan keluaran tidak stabil dikarenakan kecepatan angin yang selalu berubah-ubah. Hal ini sangat merugikan konsumen sehingga ketidakstabilan tegangan akan mengakibatkan ketidakseimbangan sistem, bahkan akan mengakibatkan life time peralatan listrik menjadi pendek. Dengan control grid side yang dilengkapi dengan Fuzzy Logic sebagai upaya pembangkit listrik dapat menghasilkan tegangan stabil sesuai yang diinginkan pada setiap kondisi kecepatan angin yang berubah- ubah. Sehingga kestabilan tegangan DC tetap terjaga. Hasil simulasi pengujian ini menunujukkan jika pengontrol fuzzy logic dapat menjaga kestabilan tegangan DC yang diinginkan yaitu 1100V.

The Effective Temperature of Dust Impact Plasmas — Olivine Dust on Tungsten Target

<p>We experimentally observe both positive and negative charge carriers in impact plasma and estimate their effective temperatures. The measurements are carried on a dust accelerator using polypyrrole (PPy)-coated olivine dust particles impacting tungsten (W) target in the velocity range of 2–18 km/s. We measure the retained impact charge as a function of applied bias potential to the control grid. The temperatures are estimated from the data fit. The estimated effective temperatures of the positive ions are approximately 7 eV and seems to be independent of the impact speed. The negative charge carriers' temperatures vary from as low as 1 eV for the lowest speeds to almost ten times higher speeds. The presented values differ significantly from previous studies using Fe dust particles. Yet, the discrepancy can be attributed to a larger fraction of negative ions in the impact plasma that likely originates from the PPy coating.</p>

Influence of turbulence integral length scale on aerostatic coefficients of bridge sections

This study investigates the influence of turbulence on the aerostatic coefficients of typical bridges by obtaining force measurements via the simulation of turbulence in wind tunnels. The traditional simulation method for turbulence based on spires and grilles cannot be employed for the accurate simulation of the large integral scale of turbulence in an actual wind field. Thus, in this study, the turbulence integral length scale was effectively increased using an active control grid. The wind fields of different turbulence integral scales were generated by controlling the vibration frequency of the active control grid. The aerostatic coefficients of five typical bridge sections (single-box girder, twin-box girder, truss girder, edge girder, and edge-box girder) were measured under turbulent and uniform flow. The test results were compared and analyzed, which revealed that the drag coefficients increased in accordance with a decrease in the reduced turbulence integral length scale, and they were lower under turbulent flow than under uniform flow.

Perancangan Sistem Grid Tie Inverter pada Pembangkit Listrik Tenaga Surya

ABSTRAKGrid Tie Inverter (GTI) merupakan inverter yang digunakan untuk mengubah energi yang dihasilkan panel surya berupa arus searah (DC) menjadi arus bolakbalik (AC). Keluaran dari GTI berupa bentuk gelombang sinusoidal yang masih belum ideal dan mempunyai nilai Total Harmonic Distortion (THD) di atas 3% serta nilai efisiensi belum mencapai 90%. Pengurangan nilai THD dan peningkatan efisiensi dapat dilakukan melalui proses kontrol switching pada inverter. Penelitian ini mengusulkan inverter dengan boost converter dua tahap, buck converter dua tahap, rangkaian switching control inverter, H-Bridge inverter dan rangkaian LC filter. Teknik switching dari inverter yang diusulkan terdiri dari kombinasi modulasi lebar pulsa sinusoida dan gelombang persegi. Berdasarkan hasil pengujian didapatkan nilai THD sebesar 4,97%. Terdapat selisih sebesar 1,97% dari nilai awal perancangan. Untuk efisiensi rata-rata inverter off-grid (tidak terkoneksi dengan PLN) sebesar 89,48% dan 79,4% untuk inverter on-grid (terkoneksi dengan PLN).Kata kunci: GTI, boost converter, buck converter, switching control,grid, THD. ABSTRACTGrid Tie Inverter (GTI) is an inverter used to convert energy resulted by solar panels in the form of direct current (DC) to alternating current (AC). The output of GTI is unideal sinusoidal and having Total Harmonic Distortion (THD) above 3% and efficiency below 90%. Reducing the THD value and increasing efficiency can be done through switching control process on inverters. This research proposed an inverter using two-stage boost converter, two-stage buck converter, an inverter switching control circuit, H-Bridge inverter and LC filter circuit. The switching technique of the proposed inverter system combined sinusoidal and square wave width modulation. The result showed THD of the proposed system is 4.97%, and still, there is a difference of 1.97% of the desired value. For average efficiency of off-grid systems (not connected with State Electricity Company/PLN) is 89.48% and 79.4% for on-grid systems (connected with PLN).Keywords: GTI, boost converter, buck converter, switching control,grid, THD