Testing the Measurement of Direct Current Injected into the Grid with an Inverter
“A photovoltaic power generation installation is made up of different elements such as: modules, support structures, fuses, cables, terminals, varistors, disconnectors, switches, connecting boxes, etc.
The most important device connected into the grid is the inverter, upon which the correct and efficient transfer of the power generated depends. The inverter current output waveform shall meet a series of requirements from the point of view of signal quality, such as the power factor and the harmonic distortion.
In order to guarantee the safety and quality of the grid provided by this type of installations, the Ministry has issued complementary technical instruction ITC-BT-40 in the Low Voltage Electrotechnical Regulation (REBT,RD842/2002), concerning low-voltage generation installations, where the following is established: “the grid and the installation shall have a galvanic separation, whether using an isolation transformer or an equivalent means.”
Technical doubts arose regarding the interpretation of the “equivalent means” and, in response, the Ministry of Industry, Tourism and Trade issued the “note for the technical interpretation of the equivalence of the galvanic separation of the connection of low-voltage generation installations”.
This note establishes the following: “If the inverter is used with a high-frequency transformer or without a transformer the direct current injected into the grid with an inverter shall be proven not to exceed 0.5% of the rated current.”
Power record and current injected with an inverter
ceis has been approved by Gas Natural – Fenosa to conduct tests on the Measurement of the Direct Current Injected into the Grid with an Inverter.