I. Sefa, N. Altin, S. Ozdemir, and M. Demirtas. Department of Electrical Education, Faculty of Technical Education, Power System Group, Gazi University, (Turkey).
SPEEDAM 2008 International Symposium on Power Electronics, Electrical Drives, Automation and Motion
dSPACE Based Control of Voltage Source Utility Interactive Inverter I. Sefa, N. Altin, S. Ozdemir, and M. Demirtas Department of Electrical Education, Faculty of Technical Education, Power System Group, Gazi University, (Turkey)
condition and recommended to control the export of power to the utility line [9]. Some type of inverters use a high frequency transformer embedded in DC-DC converter or DC-AC inverter, others are interconnected to the utility line via a line frequency transformer, and some inverters do not include transformer. Line frequency transformer can prevent DC current injection problem, provide galvanic isolation between the DC source and the utility line and makes the grounding of the PV modules easier. Although they have disadvantages like size, weight and price, the line frequency transformer is a natural solution of DC current injection [1, 3]. In utility interactive inverter applications, usually LC filters are used, but resonance frequencies of these filters are affected from line impedance. Resonance frequency variations can be prevented by using LCL filters [10]. dSPACE systems are a quite popular in controlling platform because they combine the MATLAB/Simulink simulations and hardware control. They are widely used in automation systems and car manufacturing industries [11]. All kind of analog and digital signals can also be monitored by using graphical user interfaces (GUI) designed with ControlDesk software. These GUIs shorten the design period and can visualize the control parameters [11-12]. In this study a dSPACE based utility interactive inverter has been design and implemented. In utility interactive inverter a voltage source inverter (VSI) and a PI current control is used due to its much less susceptibility to phase of synchronization errors than voltage control. LCL filter as an output filter and the line frequency transformer to prevent DC current injection to the utility line are also preferred in this system. Firstly the inverter designed is simulated in MATLAB/Simulink and then dSPACE model of the inverter is given by using this simulated Simulink model. The simulation and experimental results show that inverter output current is in phase with the line voltage and in sinusoidal waveform. Current harmonics are also found in the limits of international standards (
