Sma Solar Technology Ag

Powerlynx A/s

Danfoss Power Electronics A/s

Uffe Borup

Frerk Haase

Nils-Ole Harvest

Aksel Baagoe Jepsen

Thomas Kure Thorngreen

Christinel Dorofte

Haase Frerk

In large PV power plants, grounding of individual PV modules may lead to problems. The present invention overcomes such problems. The basis for the invention is a PV power plant comprising one or more PV generators, each comprising a PV string and an inverter with a DC input and an AC output. The PV string comprises at least one PV module and is electrically connected to the DC input of the inverter. The inverter comprises means for controlling the DC potential at the DC input depending on the DC potential at the AC output. The AC outputs of the inverters are coupled in parallel. The novel feature of the invention is that the PV power plant further comprises an offset voltage source, which controls the DC potential at the AC outputs. Thereby, the DC potential at the DC input will be indirectly controlled, and it is thus possible to ensure that the potentials with respect to ground at the terminals of the PV modules are all non-negative or all non-positive without grounding the PV modules. Ground loops can be avoided, and there is no need for the use of transformer-based inverters.

Photovoltaic power plant

A photovoltaic power plant () comprising one or more photovoltaic devices (), each device comprising at least two terminals () wherein one or more of the terminals () is connected to a switch () which is in turn connected to a point () held at a voltage relative to ground () and at least one switch () is controlled in response to one or more parameters, and a method of controlling such a power plant ().

The invention relates to a method for determining the type of connection of at least two electric devices () whereby each device comprises a similar connector arrangement. The aim of the invention is to increase the reliability during the starting up process and during the operation of a system which comprises several electric units (). According to the invention, a first device () modifies the voltage on the connector arrangement () and the modified voltage is determined as a first voltage, such that a second device () determines a second voltage on at least the connector arrangement () and determines whether an electric connection exists or not between the connector arrangements () of the devices () by comparing the determined comparison of the voltages.

Method for determining the type of connection of at least two electrical devices and system comprising several electric devices

A power converter for converting energy from a green power unit as e.g. a solar cell into energy fed into the commercial grid is described. The object is to provide a versatile modularized power converter with eased access to control of the power switches. Another object is to improve the electrical efficiency. This is achieved by using an independent controller on a DC/DC module and an independent controller on a DC/AC module, whereby the two independent controllers communicate with each other and the outside world by means of a communication bus. Further, the DC/DC module of the power converter comprises a transformer which transfers energy from the DC/DC module to the DC/AC module. This design enables independent control of the modules and eases controllability of the power switches in order to suppress retroaction from pulsations generated on the mains when supplying energy to a single phase grid. Hereby the electrical efficiency of the power converter is increased. Also, an active snubber circuit is described which further increase the efficiency.

Growing community of inventors

Sydals, Denmark

Uffe Borup