New Regenerative AC Load Function – Further Extend the Grid Simulator Capability for Micro-grid Test Application

The Chroma 61800 Series high power regenerative grid simulator capable of delivering output power up to 300kVA has been widely used for testing PV inverters, power conditioning systems (PCS) and EVSE charging stations. Lately, more and more engineers are studying the applications of micro-grids and energy storage systems. The 61800 Series not only can simulate the voltage and frequency test requirements for different regions of world, it is also capable of simulating voltage transient and abnormal conditions with synthesis of harmonic / inter-harmonic components as well. Its full four quadrants operation capability and regenerative function used to feed the energy back to the grid are the most favored by users.

Aside from the aforementioned capabilities to simulate the AC voltage test conditions, the capabilities of simulating various load conditions in order to cope with the diversified and dynamic nature of the system are also required for the micro-grid testing. It is very rare in the market to have test equipment with both AC source and AC load functions as a single unit.

Traditional AC electronic load designs mainly consist of passive and switch devices. These electronics loads can only operate in the 1st quadrant (both voltage/current in the positive region) and 3rd quadrant (both voltage/current in the negative region). The functionalities for the traditional AC electronic load are mainly limited to CR mode and rectified mode due to the design’s nature. Unlike the traditional electronics load, Chroma 61800 Series with full four quadrants and a regenerative design has further extended its test application capabilities by including the regenerative AC load function as an option with its maximum loading capability equivalent to the maximum output power rating of the unit. For instance, with the AC load option installed, the 61800 Series is capable of providing up to 180kW loading capability.

The phase lead/lag mode with phase angle setting ranging from 90 degree ~ -90 degree will simulate the corresponding voltage and current condition under an inductive or capacitive type load (see below waveforms). When the phase angle setting is in the range of 90.1 degree ~ 180 degree (-90 degree ~ -180 degree), the 61800 will become a current source, similar to a programmable inverter which is applicable for micro-grid related testing.


The Chroma 61800 Series regenerative AC load function is applicable for AC power supplies, UPS, PCS and EVSE charging station (V2L/V2H) test applications. It can simulate the effects of different loading conditions based on various home appliances, or test the PV inverter’s power quality correction functionality by deliberately setting the AC load in various reactive load conditions. The regenerative AC load is applicable for simulating the various power flow conditions related to micro-grid application for research in smart management or for balancing supply and demand loads.

Chroma uses the DSP digital control method to add the optional AC load function to the 61800 Series regenerative grid simulator. The AC load function further diversified the 61800 Series test applications ranging from academic, R&D design verification, and quality assurance to mass production.

For more information on the Chroma 61800 features and specifications, please visit Chroma’s website:   Regenerative Grid Simulator Model 61800 Series