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5.2.2 Smart functions on power inverters
The growth and spread of distributed systems, especially PVs, suggest a
future where utilities will need to accommodate high levels of DG penetra-
tion in their distribution and transmission systems. New forms of communi-
cation and interaction of distributed systems based on inverters have been
developed to maximize the benefits of DG [1].
In 2009, EPRI—Electric Power Research Institute—along with the US
Department of Energy, Sandia National Laboratories, and the Solar Electric
Power Association launched a research project to begin a process of identify-
ing and standardizing the set of capabilities that the inverter can perform to
improve the performance of the network and thus increase the level of DG
penetration without any damage to the system [12].
Based on studies carried out, EPRI published a document called Common
Functions for Smart Inverters [8] with the description of the main functions
for smart inverters, focused mainly on solar inverters and energy storage.
Smart inverter functions [8] are divided according to the control drives
and their purpose. The division according to the control drives is described
as follows:
Functions driven by an operator require direct interaction with the opera-
tor and can be divided into the following:
Basic functions: basic operations of inverters, which include remote
connection and disconnection from the grid, system monitoring
through a supervisory and displaying parameters that allow the opera-
tor to understand the behavior of the inverter.
Direct control: functions that allow the operator to limit the output
power and change the PF of the inverter also allow charging and dis-
charging of an energy storage system, if available.

Autonomous functions: functions that allow the inverter to decide on its
own since it has been supplied with logic and previous parameters. The
inverter collects measurement data at the control point for processing.
Some examples of this type of function are based on curves, such as the
Volt/Watt function, for example, which requires the inverter to decrease
the injected power as the system voltage increases.
Functions driven by independent variables: such as the autonomous func-
tions, differentiated by the data collection, which is sent here to the
inverter of some remote data stream, considering that the data can be
electric or not.
Electrical data: electrical data is sent to the inverter from a load or
generator that the inverter has been requested to follow, data from the
PCC or another point in the network can also be sent.
Indirect control: functions performed by the inverter are performed
through nonelectrical data, such as temperature, prices, and time-
based data.