Inverter based testbench for photovoltaic inverters in compliance with medium-voltage grid codes

Recently, the market for renewable energy sources like wind and photovoltaic have been growing rapidly and the total installed power has the range of conventional power plants. This leads to a need for power flow control especially under certain conditions e.g. grid failures and voltage rise along the power line. What happens if the line voltage or the frequency increases due to an excess power supply? Should the power source disconnect from the grid in the event of a voltage dip? All this questions have to be answered. Therefore, new grid codes have been established to have a standard which has to be fulfilled by all new high-power wind and photovoltaic inverters. In compliance with these new standards PV inverters have to be checked with test benches. This paper presents a new switching-inverter based test bench which has high dynamics and is capable of testing devices up to 500kW. It was recently used for certification measurements and is much cheaper than commercial linear amplifier test benches [1]. This paper focuses on fault-ride-through and frequency shift tests.