This paper describes a new high-speed HVDC line protection using wavelet technique, Based on the representation of the tavelling waves through wavelet modulus maxima, the protection criterions for HVDC line are proposed. Simulations are carried out for testing the criterions. And the influences of similar faults are discussed. The protection can detect the HVDC line fault well and identify the HVDC line fault clearly from the similar transients, such as commutation failure and AC single phase fault.

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Abstract. In Europe photovoltaic plants are mainly working in parallel mains operation. Until now, the solar plants are usually grid connected via central inverter stations or via string inverters. The logical advancement of the string concept is the separate connection of each solar module to the grid. Therefore module integrated inverters or multilevel-inverters can be used. This concept has some advantages, as minimized mismatching losses and minimized DC wiring. But the circuit complexity is of course much higher. In this paper the layout and implementation of DC/DC-converters as linkages between solar modules and multilevel-inverters will be presented.

Abstract. This paper presents a new solar multilevel inverter, based on the cascaded-multilevel converter. The main idea is that the new inverter generates a so called "highly pulsating space phasor" instead of a reference voltage. This operation mode limits the distortions. Additionally, for the first time energy redundancies between the voltage levels can be used, instead of the so far known voltage redundancies. As a result, the problem of unbalanced voltage sources can be avoided, a complex control is not necessary anymore and the MPP tracking of solar multilevel inverters can be improved considerably.

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