Description of the Frequency Droop unit calculation function inside of Generic DER components
Implementation
The Frequency droop Functionality calculates the Frequency Reference Signal
when Droop control mode is activated, based on the active
power error and specified droop characteristics. It implements a simple control
method for droop characteristics defined by offset and coefficient input values.Figure 1. Frequency droop characteristics
Changing the Droop Offset value shifts the nominal droop frequency up or down, while
changing the Coefficient value affects the slope of the droop characteristics (a
higher coefficient value leads to a higher slope). Active power
error is calculated by subtracting filtered measurement of the
active power from the reference active power. A simple first-order low-pass filter
is used for this purpose. Active power error is limited by the generic DER's Maximal
Active Power setting.
Parameters and I/O
Parameters
Active power measurement low pass filter cut-off frequency (defined with
0.1*generic DER nominal frequency)
Execution rate (equal to slower execution rate of the generic DER
component)
Inputs
Active power reference
Active power measurement
Frequency droop coefficient
Frequency droop enable
Droop nominal frequency (generic DER nom frequency + frequency droop
offset)