9440300990 Rev J
95
DECS-250
Power System Stabilizer
Figure 89. Stabilizing Signal Selection
Torsional Filters
Two torsional filters, shown in Figure 90, are available after the stabilizing signal and before the phase
compensation blocks. The torsional filters provide the desired gain reduction at a specified frequency. The
filters compensate the torsional frequency components present in the input signal.
Figure 90. Torsional Filters
Software switch SSW 4
X
enables and disables torsional filter 1 and SSW 5
Y
enables and disables
torsional filter 2.
Torsional filters 1 and 2 are controlled by a zeta numerator
Z
(Zeta Num), zeta denominator
AA
(Zeta Den),
and a frequency response parameter
BB
(Wn).
Phase Compensation
The derived speed signal is modified before it is applied to the voltage regulator input. Filtering of the
signal provides phase lead at the electromechanical frequencies of interest (0.1 to 5 Hz). The phase lead
requirement is site-specific and is required to compensate for phase lag introduced by the closed-loop
voltage regulator.
Four phase compensation stages are available. Each phase compensation stage has a phase lead time
constant
CC
(T1, T3, T5, T7) and a phase lag time constant
DD
(T2, T4, T6, T8). Normally, the first two lead-
lag stages are adequate to match the phase compensation requirements of a unit. If needed, the third
and fourth stages may be added through the settings of software switches SSW 6
EE
and SSW 7
FF
. Figure
91 illustrates the phase compensation stages and associates software switches.
Figure 91. Phase Compensation
Washout Filter and Logic Limiter
The output of the phase compensation stages is connected, through a stabilizer gain stage, to the
washout filter and logic limiter.
Software switch SSW 9
GG
enables and bypasses the washout filter and logic limiter. The washout filter has
two time constants: normal
HH
and limit
II
(less than normal).
P0026-19
12-09-04
Derived
Speed
Deviation
SSW 2
Washed
Out Speed
SSW 3
Stabilizing
Signal
Washed
Out Power
Stabilizing
Signal
2
2
2
2
2
2
n
n
d
n
n
n
w
s
w
z
s
w
s
w
z
s
+
+
+
+
2
2
2
2
2
2
n
n
d
n
n
n
w
s
w
z
s
w
s
w
z
s
+
+
+
+
Phase
Compensation
P0026-20
12-09-04
Disable
SSW 5
SSW 4
Enable
Disable
Enable
1 + s T
1
1 + s T
2
1 + s T
3
1 + s T
4
PSS Output Before
Gain and Limits
Stabilizing
Signal
Include
Exclude
SSW 6
1 + s T
5
1 + s T
6
SSW 7
1 + s T
7
1 + s T
8
P0026-21
12-09-04
Include
Exclude
Содержание DECS-250
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Страница 6: ...iv 9440300990 Rev J Revision History DECS 250 ...
Страница 16: ...xiv 9440300990 Rev J Contents DECS 250 ...
Страница 20: ...4 9440300990 Rev J Introduction DECS 250 ...
Страница 28: ...12 9440300990 Rev J Power Stage DECS 250 ...
Страница 32: ...16 9440300990 Rev J Voltage and Current Sensing DECS 250 ...
Страница 40: ...24 9440300990 Rev J Synchronizer DECS 250 ...
Страница 52: ...36 9440300990 Rev J Auxiliary Control DECS 250 ...
Страница 56: ...40 9440300990 Rev J Contact Inputs and Outputs DECS 250 ...
Страница 84: ...68 9440300990 Rev J Limiters DECS 250 ...
Страница 108: ...92 9440300990 Rev J Power System Stabilizer DECS 250 Figure 85 PSS Function Blocks and Software Switches ...
Страница 114: ...98 9440300990 Rev J Power System Stabilizer DECS 250 Figure 96 PSS Parameter Settings ...
Страница 124: ...108 9440300990 Rev J Stability Tuning DECS 250 ...
Страница 126: ...110 9440300990 Rev J Mounting DECS 250 Figure 103 Overall and Projection Mounting Dimensions ...
Страница 127: ...9440300990 Rev J 111 DECS 250 Mounting Figure 104 DECS 250 Escutcheon Plate Dimensions ...
Страница 128: ...112 9440300990 Rev J Mounting DECS 250 Figure 105 Panel Cutting and Drilling Dimensions for DECS 250 Panel Mounting ...
Страница 198: ...182 9440300990 Rev J Timekeeping DECS 250 ...
Страница 210: ...194 9440300990 Rev J CAN Communication DECS 250 ...
Страница 304: ...288 9440300990 Rev J Maintenance DECS 250 ...
Страница 316: ...300 9440300990 Rev J Specifications DECS 250 ...
Страница 334: ...318 9440300990 Rev J Analog Expansion Module DECS 250 ...
Страница 341: ...9440300990 Rev J 325 DECS 250 Contact Expansion Module Figure 188 CEM 2020 Input Contact and Output Contact Terminals ...
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