Medium voltage string inverter for photovoltaics

The Fraunhofer Institute for Sun Power Techniques ISE has advanced and operates the sector’s first medium-voltage string inverter for large-scale energy vegetation. Through feeding energy to the medium voltage grid, the MS-LeiKra mission workforce demonstrated that PV inverters are technically in a position to dealing with upper voltage ranges.

Some great benefits of photovoltaics come with large price and useful resource financial savings on passive parts and cables. The tool lays the basis for a brand new gadget thought for the following era of large-scale photovoltaic energy vegetation, which may also be implemented to wind generators, electrical mobility and business packages.

Trendy PV string inverters have an output voltage between 400 VAC and 800 VAC. Despite the fact that the manufacturing of energy vegetation is rising incessantly, the voltage has now not but higher. There are two causes for this: First, development a extremely environment friendly, compact inverter in accordance with silicon semiconductors is difficult. Secondly, there are these days no PV requirements that handiest quilt the low voltage vary (most 1500V DC / 1000V AC).

In a mission of the German Federal Ministry for Financial Affairs and Local weather Motion (BMWK), Fraunhofer ISE, in cooperation with Siemens and Sumida, has advanced an inverter that permits the output voltage to be higher to the medium voltage vary (1500 V). At 250 kVA. The important thing to that is using silicon carbide semiconductors, that have the next blockading voltage.

The analysis workforce additionally applied a extra environment friendly cooling thought the usage of warmth pipes, which reduces the volume of aluminum required.

Skinny cables be offering large financial savings possible

The typical PV energy station calls for tens of kilometers of copper cable. Expanding the voltage creates nice possible: with as of late’s possible output voltage of 800 VAC, a 250 kVA string transformer calls for cables with a cross-section of no less than 120 mm². Through expanding the voltage to 1500 VAC, the cable cross-section will also be lowered to 35 mm². This in flip reduces copper intake by means of about 700 kilograms consistent with kilometer of cable.

“Our useful resource analyzes display that within the medium time period, the electrification of the ability gadget will result in copper shortage. Expanding the voltage lets in us to save lots of treasured assets,” says Prof. Dr. Andreas Piet, Director of the Fraunhofer Sun Institute. ISE Power Techniques.

With the “MS LeiKra” mission, they’re going past the low voltage requirements (<1000 VAC / <1500 VDC). There are these days no PV requirements for this vary. That is why the mission workforce additionally works on parameters that can consequence from higher effort.

Having effectively fed energy into the medium voltage grid, the analysis workforce is now in search of sun farm builders and grid operators to check the ability plant thought within the box.

But even so photovoltaics, low-voltage bypass could also be necessary for different packages, reminiscent of wind generators, the place rising gadget capacities additionally require cables with vast cross-sections. The similar applies to charging infrastructure for big electrical automobiles and automobile fleets, and business networks, the place medium-voltage transformers may just save a large number of subject matter if cable cross-sections may well be lowered.

Equipped by means of the Fraunhofer Institute for Sun Power Techniques (ISE).