A new active Q-f droop anti-islanding algorithm is proposed. The method is based on frequency and reactive power cross-correlation measures. The proposed control technique is intended to fulfil recent and future grid code requirements. The algorithm looks for a zero non-detection zone, adding low disturbances, working with long frequency excursions and nondependency of the power factor setpoint. The method was verified using a set of simulation models developed in PSCAD environment. The tests show results for several quality factors and different active power levels. Also, a comparative against other anti-islanding methods is presented. Experimental and simulation tests provide further insight on the controllers performance under different working conditions, considering several quality factors and active power levels. Moreover, its performance is assessed comparing the proposed controller behavior against state-of-theart anti-islanding methods.

Abstract:Power converters are the basic unit for the transient voltage fault ride through capability for most renewable distributed generators (DGs). When a transient fault happens, the grid voltage will drop suddenly and probably will also suffer a phase-jump event as well. State-of-the-art voltage fault control techniques regulate the current injected during the grid fault. However, the beginning of the fault could be too fast for the inner current control loops of the inverter, and transient over-current would be expected. In order to avoid the excessive peak current of the methods presented in the literature, a new fast peak current control (FPCC) technique is proposed. Controlling the peak current magnitude avoids undesirable disconnection of the distributed generator in a fault state and improves the life expectancy of the converter. Experimental and simulation tests with high power converters provide the detailed behaviour of the method with excellent results.

Abstract:Power converters are the basic unit for the transient voltage fault ride through capability for most renewable distributed generators (DGs). When a transient fault happens, the grid voltage will drop suddenly and probably will also suffer a phase-jump event as well. State-of-the-art voltage fault control techniques regulate the current injected during the grid fault. However, the beginning of the fault could be too fast for the inner current control loops of the inverter, and transient over-current would be expected. In order to avoid the excessive peak current of the methods presented in the literature, a new fast peak current control (FPCC) technique is proposed. Controlling the peak current magnitude avoids undesirable disconnection of the distributed generator in a fault state and improves the life expectancy of the converter. Experimental and simulation tests with high power converters provide the detailed behaviour of the method with excellent results.