Fault ride through control by using new real time symmetrical coordinate transformation

Fault ride through (FRT) ability is indispensable for the power conditioners connected to the ac utility system. The power conditioner of the photovoltaic system in Japan is required to remain connected when the utility power system fault occurs under certain condition. The most popular fault is 1 line-to-ground fault and the next is 2 line-short fault. Both cause the imbalance voltages and currents in 3-phase power system. To optimize the output power from the power conditioner of the photovoltaic system, the detection and the proper control scheme of the imbalanced condition is important factor. In this paper, new development of the signal processing method by using the complex number algebra in real time system is shown. The fast detection of the imbalanced condition and the limit of the current to perform FRT are shown by the computer simulations and the experiments.