Translation of "Mittelspannungstransformator" in English

The MV transformer is modularly extensible with medium voltage switchgear, oil containment and tracker transformer.

Here, a three-phase transformer, for example, a middle voltage transformer, may also be provided.

A circuit breaker 13 is arranged on the medium-voltage side between the medium-voltage transformer 5 and the medium-voltage grid 4 .

The supply voltages are measured on the AC voltage side 17 of the inverter 12, preferably between the filter 14 and the medium-voltage transformer 15, and are supplied together with the ground potential via corresponding lines 19 to the control device 13 as measured voltage signals.

The electrical power produced by the generator 4 in conjunction with the converter 5 is emitted to a network 9 via a line 15 and a medium-voltage transformer 19, which is normally arranged in the base of the tower.

As the first product to come from the partnership, SMA presented a new type of solution at the trade fair that combines a 2.5-megawatt central inverter from SMA with a medium-voltage transformer and medium-voltage switchgear from Siemens as a turnkey solution in a standard container.

The inverter circuit 10 includes an intermediate dc circuit 11, an inverter 12, a filter 14, a medium-voltage transformer 15 and an electronic control device 13, for example a digital signal processor DSP.

For example, the transformer 3 is a medium-voltage transformer, which steps down from a higher 20 kV supply level to a 400 volt undervoltage level and which accordingly connects an overvoltage grid (20 kV) to an undervoltage grid (400 V).

In the lower region of the lower there is the rectifier 9 and the medium voltage transformer 8 (and/or additional electrical devices).

A connecting line 13, which passes through the tower 10 to a medium-voltage transformer 8 arranged at the tower base is connected to said converter 3 .

In this case, the transformer 11, which is generally in the form of a medium-voltage trans-former of the wind energy installation 1, is normally connected between the test device 2 and the wind energy installation 1 .

The circuit divides the otherwise customary medium-voltage transformer in particular into a plurality of individual windings or even individual transformers, which have smaller dimensions and therefore allow higher frequencies.

A line 17 is connected to the generator 15 and to the converter 16, and transports the electrical power that has been produced through the tower 10 to a medium-voltage transformer 18, which is arranged at the foot of the tower 10, for passing on into a power supply system (not illustrated).

The disclosure relates to a method for operating a photovoltaic system comprising a photovoltaic generator comprising a plurality of photovoltaic modules, at least one inverter and at least one medium-voltage transformer for feeding electric power into a medium-voltage grid.

Furthermore, the low-voltage AC contactors can be used in order to decouple the respective inverter selectively from the medium-voltage transformer in the event of an overcurrent or a short circuit, in the event of infringement of the required grid parameters (voltage, frequency, fed reactive power etc.) or in the event of failure of an inverter.

Furthermore, it is known to arrange an AC disconnecting element between a medium-voltage transformer and the energy supply grid, which AC disconnecting element acts as an AC-side protection element.

The article “Advanced, High-Reliability, System-Integrated 500-kW PV Inverter Development”, R. West, Final Subcontract Report NREL/SR-520-43839, 2008, likewise describes a photovoltaic system in which a DC switching element is arranged between photovoltaic modules and an inverter, and an AC disconnecting element is provided between a medium-voltage transformer and the energy supply grid.

In a method for operating a photovoltaic system for feeding a medium-voltage grid, the photovoltaic system has a photovoltaic generator comprising a plurality of photovoltaic modules, at least one inverter and at least one medium-voltage transformer.

In this case, the medium-voltage transformer is connected on the primary side directly to a low-voltage AC output of the inverter, and the inverter is connected to the photovoltaic generator via a DC input, wherein the inverter, depending on its design, permits reverse currents from the low-voltage AC output to the DC input.

The method is characterized by the fact that in the event that there is insufficient generation of electric power for the feed by the photovoltaic modules of the photovoltaic system, the inverter remains connected on the AC side to the medium-voltage grid via the medium-voltage transformer, and the inverter remains connected on the DC side to the photovoltaic generator.

In this case, the medium-voltage transformer is connected on the primary side directly to a low-voltage AC output of the inverter and the inverter is connected to the photovoltaic generator via a DC input.

Directly in this case means in particular that no switching element which can be actuated or can close automatically is provided between the inverter 21 and the medium-voltage transformer 31 .

In the example shown, precisely one medium-voltage transformer 31 a, b, c is provided for each inverter 21 a, b, c .

However, it is also conceivable for two or more inverters to lead to a medium-voltage transformer, which may be provided with a plurality of primary windings.