Grid-connected inverter to the Internet

Grid-connected PV inverters have traditionally been thought as active power sources with an emphasis on maximizing power extraction from the PV modules. While maximizing power transfer remains a top priority, utility grid stability is now widely acknowledged to benefit from several auxiliary services that grid-connected PV inverters may offer.

In the grid-connected inverter, the associated well-known variations can be classified in the unknown changing loads, distribution network uncertainties, and variations on the demanded reactive and active powers of the connected grid.

The control design of this type of inverter may be challenging as several algorithms are required to run the inverter. This reference design uses the C2000 microcontroller (MCU) family of devices to implement control of a grid connected inverter with output current control.

Every algorithm for grid-connected inverter operation is based on the estimation or direct measurement of grid-voltage frequency and phase angle. Both parameters are fundamental for correct operation and special care must be taken in their detection to avoid the influence of any external noise.

The user must not touch the board at any point during operation or immediately after operating, as high temperatures may be present. Do not leave the design powered when unattended. Grid connected inverters (GCI) are commonly used in applications such as photovoltaic inverters to generate a regulated AC current to feed into the grid.

Grid-Following Inverters (GFLI) and Grid-Forming Inverters (GFMI) are two basic categories of grid-connected inverters. Essentially, a grid-following inverter works as a current source that synchronizes its output with the grid voltage and frequency and injects or absorbs active or reactive power by controlling its output current.