Grid emulation
First, let’s distinguish between grid emulators and AC power supplies. With AC power supplies, we can simulate grid voltage and frequency at a certain power. This is fine if we want to test a DUT (Device Under Test) against, for example, the various standards that apply to equipment on our power grid. Think of the IEC-61000-4-xx and IEC 61000-3-xx standards and many others.
We can do this with most AC power supplies, but the grid emulator has the additional feature that it can also work with negative currents and thus feed energy back into the grid. Of course, there are also conditions attached to this and these are actually the same conditions the solar panel inverter must meet.
Incidentally, these conditions vary from country to country, even within the European Union. Hence also the different country codes in solar inverters.
With a micro grid, we have a different situation. Here, the voltage and frequency is not dictated by the grid connection but the inverter itself has to generate the right voltage, waveform and frequency. So to test this, different instrumentation is needed. See Micro grid installations for this.
Within the TTMS product range, we have several manufacturers with grid emulators. Here is an overview per supplier:
Model | Max VI-n | Max Freq | Max power | |
Cinergia | GE+ vAC | 295Vrms | 100Hz | >1MVA |
Cinergia | GE/EL vAC | 295Vrms | 100Hz | >MVA |
Cinergia | GE+ vAC SIC | 295 Vrms | 1.000Hz | 400kVA |
Pacific Power | AZX | 440Vrms | 1.000Hz | 400kVA |
Itech | IT7900 | 350Vrms | 150Hz | 960kVA |
Itech | IT7900P | 350Vrms | 150Hz | 960kVA |
One of the tests to be carried out on solar panel inverters is the anti-island test. This involves checking whether the inverter system does switch off within a certain time if the grid voltage drops.
To perform this test, the grid emulator must be equipped with an AC load function with an RLC setting. Only both Itech models (IT7900 and IT7900P) have this solution provided as standard.
Back to the overview