Symo power inverter, Source: Fronius International GmbH

Symo power inverter, Source: Fronius International GmbH

Voltage control with PV power inverter

FRONIUS INTERNATIONAL GmbH, the largest Austrian producer of power inverters, has a leading position in the world market for solar electronics. Electronic control of PV facilities has been one of the company‘s concerns for many years, and it is constantly developing brand-new power inverter systems that convert DC – which the PV modules generate – into usable AC. The electricity produced in this way can then be consumed on the spot or fed into the grid.

Due to the expansion of PV, it will be necessary to integrate numerous small local suppliers into the existing electrical networks in the future. This might lead to difficulties in low-voltage grids, since some segments are already at the limits of their capacity. The main challenge here is to maintain a stable voltage. Smart Grid approaches offer a possible solution to this problem; these should feature two-way communication between suppliers, consumers and storage facilities, and are intended to make intelligent energy management possible. Products to help with this, and suitable control strategies, are currently undergoing development and testing.

In the morePV2grid project FRONIUS, in collaboration with research partners and grid operators, has developed a strategy for voltage control by means of power inverters, and tried it out with eight test units in a field trial in Upper Austria.

As a follow-on 140 units are currently undergoing testing as part of the DG Demonet Smart LV Grid project in Salzburg and Upper Austria. The goal is for numerous local PV facilities to contribute to keeping grid voltage stable by adjusting their active and reactive power autonomously, without higher-level system and communication engineering. In this way it should be possible  to integrate a large number of PV facilities into the grid at reasonable cost.

These projects are not only concerned with how effective the control strategies are; special attention is paid to how often they are needed and to possible effects on the PV facilities‘ energy yield. In addition, recommendations are being worked out for the relevant national and international standards committees.