Discrete-time or continuous-time second-order low-pass filter
Simscape / Electrical / Control / General Control
The Second-Order Low-Pass Filter (Discrete or Continuous) block implements a second-order low pass filter in conformance with IEEE Std 421.5-2016. In the standard, the filter is a single input, single output signal conditioner that is used in the Power System Stabilizer PSS1A.
In the PSS1A, the filter accounts for some of the low-frequency effects of high-frequency torsional filters. It can also help shape the gain and phase characteristics of the stabilizer.
To switch between continuous and discrete implementations of the Second-Order Low-Pass Filter (Discrete or Continuous) block, adjust the Sample time parameter value.
u— Filter input
y— Filtered output
Filtered output. The output has the same number of elements as the input.
Coefficient of s, A1— A1 coefficient
0.1(default) | positive scalar
A1, the signal conditioning frequency filter coefficient of s.
Coefficient of s^2, A2— A2 coefficient
0.2(default) | positive scalar
A2, the signal conditioning frequency filter coefficient of s2.
Sample time (-1 for inherited)— Block sample time
-1(default) | 0 | positive scalar
Time between consecutive block executions. During execution, the block produces outputs and, if appropriate, updates its internal state. For more information, see What Is Sample Time? (Simulink) and Specify Sample Time (Simulink).
For inherited discrete-time operation, specify
discrete-time operation, specify a positive integer. For continuous-time operation,
If this block is in a masked subsystem, or other variant subsystem that allows you to switch between continuous operation and discrete operation, promote the sample time parameter. Promoting the sample time parameter ensures correct switching between the continuous and discrete implementations of the block. For more information, see Promote Parameter to Mask (Simulink).
 IEEE Recommended Practice for Excitation System Models for Power System Stability Studies. IEEE Std 421.5-2016. Piscataway, NJ: IEEE-SA, 2016.