Grid-following inverter

A grid-following inverter needs an external voltage source, normally the utility grid, before it can run and produce power. It follows the grid voltage and frequency it measures and changes its output current waveform and amplitude to deliver the real and reactive power it is asked for. A typical grid-tied PV inverter turns DC from the modules into AC at the grid's frequency and phase, supplies local loads and exports the surplus. It keeps checking the grid and the PV array, and it enters its protection routine as soon as the grid becomes abnormal. When the external voltage is lost, a grid-following battery system trips or goes into a faulted state on its own. In this mode the inverters give no independent voltage or frequency support. A plant controller can calculate power commands from metered voltage and frequency, and reactive current injection for low-voltage events can be turned on if required. The NEC calls this an interactive inverter: it runs in parallel with the utility and can deliver power to it. It is also called grid-tied, grid-interactive or utility-interactive. The opposite approach is the grid-forming inverter, which acts as a standalone voltage and frequency source.

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• sentence 1: support check: partial - Requirement of an external voltage source is stated, but 'normally the utility grid' is not stated in the passages.
• sentence 7: support check: partial - Definition from NEC with the alternative names is given, but the term is 'Interactive Mode' inverter; the wording matches mostly, though equating it to grid-following is implied rather than stated.
• sentence 1: review: partial - The Tesla passages say grid-following mode needs an external voltage source to operate and produce power, but 'normally the utility grid' is not stated and the passages describe a battery system rather than inverters in general. -->