Fractional Order Repetitive Controller Based Current Control of Grid Interactive Voltage Source Inverter in Renewable Energy Systems

Öz

Many renewable energy sources are connected to the grid with the installation of new electrical power systems. Due to power electronic devices in these systems, significant increase in the harmonic content affects the power values of these systems. Therefore, it is essential to develop efficient control strategies of grid-connected power electronics-based new energy sources, which pose a system operating risk and cause a reduction in energy quality. In this study, a fractional delay repetitive controller was investigated in parallel with proportioanal-integral (PI) controller. A fractional delay has been added to the controller to increase suppression of inverter output current harmonics in case the grid frequency and voltage are exposed to disturbances due to renewable energy power systems. The operating principle and stability of the combined controller were analyzed and parameter design was performed on the basis of a three-phase L type filter and a grid-connected inverter. It has been observed that ability of the controller to suppress current harmonics and dynamic control response are quite good in case of disturbed grid frequency and voltage. In this case, current harmonics have been reduced from 60% to below 5% according to IEEE519 standards. Effective dynamic control responses of grid- interacted inverter, simulated in MATLAB/Simulink environment, under harmonic distortion are comparatively presented in this study.

Anahtar Kelimeler

• Voltage source inverter
• harmonics
• repetitive control
• current control
• renewable energy

Yenilenebilir Enerji Sistemlerinde Şebeke Etkileşimli Gerilim Kaynaklı Eviricilerin Kesir Dereceli Tekrarlamalı Kontrolcü Tabanlı Akım Kontrolü

Öz

Çok sayıda yenilenebilir enerji kaynağı, yeni elektrik güç sistemlerinin kurulması ile beraber şebekeye bağlı çalışmaktadır. Bu sistemlerdeki güç elektroniği cihazları sebebi ile harmonik içeriğin önemli ölçüde artması güç değerlerini etkiler. Bu nedenle, sistem işletme riski oluşturan ve enerji kalitesinin azalmasına neden olan şebekeye bağlı güç elektroniği tabanlı yeni enerji kaynaklarının verimli kontrol stratejilerinin geliştirilmesi elzemdir. Bu çalışmada, oran-integral (PI) kontrolcüye paralel olarak kesirli gecikmeli tekrarlayıcı kontrolcü araştırılmıştır. Yenilenebilir enerji güç sistemleri kaynaklı olarak şebeke frekansı ve geriliminin bozucu etkilere maruz kalması durumunda evirici çıkış akımı harmoniklerini bastırma özelliğini artırmak için kontrolcüye kesirli değerli gecikme eklenmiştir. Birleşik kontrolcünün çalışma ilkesi ile kararlılığı analiz edilmiş ve parametre tasarımı üç fazlı L tipi filtre ile şebekeye bağlı evirici temelinde gerçekleştirilmiştir. Kontrolcünün, şebeke frekansının ve geriliminin bozulması durumunda akım harmoniklerini bastırma yeteneğinin ve dinamik kontrol cevabının oldukça iyi olduğu gözlenmiştir. Bu durumda akım harmonikleri %25 seviyelerinden IEEE519 standartlarına göre %5’in altına düşürülmüştür. Bu çalışmada, MATLAB/Simulink ortamında benzeşimi gerçekleştirilen şebeke etkileşimli eviricinin harmonik bozulma altında etkili dinamik kontrol cevapları karşılaştırmalı ortaya konulmuştur.

Anahtar Kelimeler

• Gerilim kaynaklı evirici
• harmonikler
• tekrarlamalı kontrol
• akım kontrolü
• yenilenebilir enerji

Kaynakça

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