Penukar pelbagai peringkat modular (MMC) telah menjadi topologi yang paling popular dalam aplikasi voltan tinggi dan kuasa tinggi. Kehadiran sebilangan besar sub-modul (SM) dalam MMC meningkatkan kemungkinan berlakunya kerosakan. SM yang rosak boleh membawa gangguan kuaasa mahal. Untuk mengatasi kerosakan SM dalam MMC, kawalan toleransi kerosakan dengan penggunaan sandaran lebihan telah digunakan. Dalam tesis ini, dua jenis strategi kawalan toleran yang berbeza telah dikaji, iaitu skim simpanan sejuk dan skim simpanan panas. Model MMC fasa tunggal telah dibina dalam MATLAB Simulink. Model MMC disepadukan dengan skim simpanan sejuk dan skim simpanan panas. Situasi kerosakan salah satu SM disebabkan oleh litar pintas telah ditetapkan pada masa tertentu, t = 0.021s. Simulasi telah dijalankan untuk melihat prestasi kedua-dua kawalan toleransi kerosakan. Simulasi menunjukkan bahawa skim simpanan panas mempunyai prestasi yang lebih baik berbanding dengan skim simpanan sejuk kerana tiada lonjakan hadir dalam arus keluaran dan voltan keluaran. Selain itu, skim simpanan panas mempunyai masa tindak balas yang lebih pendek (t=0.699ms) berbanding skim simpanan sejuk (t=1ms). Kualiti gelombang sementara lebih baik dalam skim simpanan panas berbanding skim simpanan sejuk. Kesimpulannya, skim simpanan panas mempunyai prestasi yang lebih baik berbanding skim simpanan sejuk.
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Modular multilevel converter (MMC) has become the most attractive topology in the high-voltage and high-power application. Presence of the large number of sub-modules (SMs) in the MMC increases the likelihood of the fault occurrence. A faulty SM can essentially lead to expensive downtime. In order to cope with the SM fault of MMC, a fault-tolerant control with redundancy backup is used. In this thesis, two different types of fault-tolerant control strategies are studied, which are cold-reserve scheme and hot-reserve scheme. A single-phase MMC model is constructed in MATLAB Simulink. The MMC model is integrated with cold-reserve scheme and hot-reserve scheme. A situation that one SM fault due to short circuit is set at a fixed time, t = 0.021s. Simulation is carried out to observe the performances of both fault-tolerant controls. The simulation shows that hot-reserve scheme has better performance compared to cold-reserve scheme as there is no surge present in the output current and output voltage. Besides that, hot-reserve scheme has shorter response time (t=0.669ms) compared to cold-reserve scheme (t=1ms). The transient waveform quality is better in hot-reserve scheme compared to cold-reserve scheme. Therefore, it is concluded that hot-reserve scheme possesses better performance compared to cold-reserve scheme.
Fault-tolerant control of modular multilevel converter using cold-reserve scheme and hot-reserve scheme / Oi Ching Xien