دانلود رایگان مقاله انگلیسی روش تشخیص جزیره ای شدن مستقل ولتاژ و سوئیچ ولتاژ پایین از طریق یک مبدل PV دو مرحله ای - نشریه IEEE

Abstract

This paper presents an islanding detection method for a two stage PV inverter. The novelty in this method is that it doesn’t rely on instantaneous value of the grid voltage for identifying the islanded condition. Instead, the islanding condition is detected by the saturation of the PI controller of the outer voltage control loop. This makes the proposed detection algorithm more reliable compared to other voltage based detection algorithms, as it is immune to malfunctions caused by the sudden load changes or other transients. In addition, a simple but accurate implementation strategy for low voltage ride through (LVRT) operation is also proposed and integrated with the anti-islanding operation. Both these methods are placed inside the overall control structure that can perform seamless transition between grid-connected and stand-alone modes of operation. The simulation results demonstrate the effectiveness of the proposed anti-islanding and LVRT techniques. Finally, hardware results on a 2 KW laboratory prototype are presented for experimental verification of the proposed anti-islanding and LVRT schemes.

V. CONCLUSIONS

In this paper an integrated control algorithm for islanding detection and LVRT operation of a two-stage PV inverter is proposed and verified. Islanding is detected from the status of current saturation at the output of the inverter voltage control loop. The advantage of this method is that it is insensitive to disturbances as it does not depend upon the instantaneous value of the grid voltage. The islanding detection time is less than 2 Sec in all cases. It therefore satisfies IEEE1547 standard. The LVRT algorithm proposed here is very accurate as it is independent of the nature of the voltage sag. This is because the LVRT specification has been formulated as an inequality condition and this condition can be checked by integration of direct axis component of the instantaneous grid voltage. The developed control structure is versatile as it can be used for both stand-alone and gridconnected mode of operation with seamless transition of modes in which interactive islanding detection and LVRT features are incorporated along with the MPPT. The algorithm is tested comprehensively in PLECs simulation. The operation of the complete system is tested using a digital platform consisting of DSP TMS320F2812. It is observed that the proposed algorithm ensures fast islanding detection and provides a reliable low voltage ride through performance.