Siemens SINAMICS S120 System Manual page 94

Commissioning
7.5 Commissioning example of an infeed with dynamic grid support for a power grid
Parameter Value
p5501 e.g. 1
p5504 e.g.:
p5504[0] = r5488[0]
p5504[1] = r5488[1]
p5505[0..3] In accordance with coun-
try-specific guideline
p5506[0..3] In accordance with coun-
try-specific guideline
p5507[0] e.g. 20 ms
p5507[3] e.g. 8 ms
1)
p5508[0] e.g. -30 V
p5509[0] e.g. 20 %
p5509[1] e.g. 0.1 %
94
Comment
BI: Dynamic grid support activation
Signal to activate the dynamic grid support.
A difference to normal operation of the Active Line Module when using
p5501 = 1 only becomes effective if the grid voltage lies outside the selected
tolerance band p5505[0, 2]: In this particular case (r5502.1 = 1) an additional
reactive power is injected into the grid, whose magnitude with p5506 depends
on the grid voltage error. Steady-state reactive current setpoints, which apply
independent of instantaneous grid voltage fluctuations, must still be entered
using p3610/p3611.
When support is activated (i.e. p5501 = 1) the internal current control is extend-
ed, so that grid faults are ridden through with a defined grid current; the Active
Line Module is only shutdown (fault tripped) to protect the power unit and the
Active Interface module itself (overload, overvoltage/undervoltage in the DC
link). For remaining voltage and frequency deviations, to protect the grid, the
grid monitoring must be set according to local requirements and regulations.
CI: Dynamic grid support voltage signal source
Interconnection with r5488 is especially required, if a transformer is used and
the connection point of the power generating unit is not located at the connec-
tion side of the Active Line Module, but instead is on the medium voltage side,
for example.
Dynamic grid support characteristic voltage values
1)
Dynamic grid support characteristic reactive current setpoint
1)
Dynamic grid support times, minimum time dynamic grid support
1)
The adjustable parameter defines the time that the grid voltage must again lie
within tolerance limits before support with a dynamic reactive current is exited.
Depending on the particular grid code, here, significantly lower values must be
selected than the default setting (e.g. for China).
Dynamic grid support times, smoothing time instantaneous value
The adjustable parameter defines the fast smoothing time for breaking down the
voltage into a positive and negative sequence system. Especially for grids with
high inductance, the smoothing should be greater than the default setting in
order to avoid resonance problems.
Dynamic grid support Vdc threshold, offset overvoltage
1)
A sudden load change at the beginning of a grid short-circuit increases the risk
of a fault trip due to Vdc overvoltage. Using this adjustable parameter, a thresh-
old for the DC link voltage is defined (Vdc_max – p5508[0]). When this is ex-
ceeded, then the Active Line Module control responds with an increased active
power output. For photovoltaic applications, for example, the threshold must be
selected to be higher than the no-load voltage of the photovoltaic array.
Dynamic grid support scaling values, ramp reactive current at the start/end of
grid support
If, in the grid code for dynamic support current, rise times of > 30 ms are speci-
fied, then generally, ramp gradients of p5509[0] = 10 % .. 20 % are sufficient,
and avoid control variables from overshooting.
Dynamic grid support scaling values, reactive current ramp when the Vdc
threshold is exceeded
For the setting p5509[1] = 0.1 %, the support current is not reduced when
reaching the Vdc threshold p5508. This is specified in many grid codes.
System Manual, 04/2015, A5E03347436A
Grid infeed