This model is based on the IEEE std 421.5 type PSS4B multi-band power system stabilizer model.
Model Overview
The PSS4B structure is based on separate bands targeting the low-, intermediate-, and high-frequency modes of oscillations. Each of the three bands is made of a differential band pass filter, a gain, and a limiter as shown below, and the outputs of the three bands are summed and passed through a final limiter producing the stabilizer output VST.
Input/Output
The model’s inputs and outputs are described in the following table:
I/O Name | Type (unit) | Description |
|---|---|---|
dw | Input (pu) | Speed deviation |
VST | Output (pu) | Stabilizer output |
Parameters
Expanding the PSS4B diagram displays the block diagram shown below.
PSS4B has two modes: Detailed mode – which considers all the lead-lag blocks given in the Figure 1 with detailed time constant and gain inputs specified by the user; simplified mode – which considers only the first lead-lag block of the complete structure as shown in dotted part of Figure 1. Figure 2 shows the block diagram for simplified mode only. The value of R (=T2/T1) is taken as 1.2 (2).
Figure 1. PSS4B Complete Block Diagram
Figure 2. PSS4B Simplified mode diagram
Name | Unit | Description |
|---|---|---|
KL1, KL2, KL | pu | Gains of the positive and negative branches of the differential filter in the low-frequency band and the overall gain KL of the low-frequency band, |
TL1 to TL12, KL11, KL17 | s | Low frequency time constants of positive and negative lead-lag blocks and associated gains |
KI1, KI2, KI | pu | Positive and negative branches gains of the differential filter of intermediate frequency band and the overall gain KI of intermediate band |
TI1 to TI12, KI11, KI17 | s | Intermediate frequency time constants of positive and negative lead-lag blocks and associated gains |
KH1, KH2, KH | pu | Positive and negative branches gains of the differential filter of the high frequency band and the overall gain KH |
TH1 to TH12, KH11, KH17 | s | High frequency time constants of positive and negative lead-lag blocks and associated gains |
FH, FI, FL | Hz | High, Intermediate, Low frequency bands. (applicable only for simplified model). |
Detailed | 1: Detailed model; 0- Simplified model | |
LIM_VH, LIM_VI, LIM_VL, LIM_VS | pu | Limits on output of high frequency, intermediate frequency, low frequency, and stabilizer output |
Reference
- "IEEE Recommended Practice for Excitation System Models for Power System Stability Studies," in IEEE Std 421.5-2005"
- Grondin, R., I. Kamwa, L. Soulieres, J. Potvin, and R. Champagne, “An approach to PSS design for transient stability improvement through supplementary damping of the common low frequency,” IEEE Transactions on Power Systems, 8(3), August 1993, pp. 954-963.