Siemens SINAMICS S120 System Manual page 135

● The priority for providing reactive power for dynamic grid support can be briefly
automatically deactivated if the DC link voltage comes close to the upper shutdown limit.
In order to avoid a protective shutdown, the reactive current is reduced via p5508 – and
the full active power is available to reduce the DC link voltage down to zero.
● For the previously mentioned conditional current limits, a differentiation is made between
– the permissible tolerance range of the grid voltage (symmetrical and non symmetrical)
– and the detection of a grid short-circuit due to undervoltage
Supplementary notes/setting recommendations for the parameterization:
● If, after the grid returns, active power must be quickly re-established (for instance, China),
then the "Minimum time dynamic grid support" p5507[0] must be set = 10 ... 20 ms.
● If the permissible time to establish the reactive current after the start of a grid fault is long
enough, then the starting ramp for the support current should be reduced (e.g.
p5509[0] = 10 %). This can avoid overvoltages at the start of a fault.
● In many cases, during a grid fault, it is not permissible that the reactive current is
reduced, if the DC link voltage reaches its shutdown limits (e.g. p5508 = -40 V). To do
this, set p5509[1] = 0.1 %.
● If reactive current support is also required for non-symmetrical grid faults (e.g. China
GB/T 19964:2012), then the setting p5509[7] = 100 % is necessary. Further, for riding
through all fault types, we recommend p5509[8] = 0.1 % as well as
p5509[11] = 20 ... 50 %. When required, lower and higher values are also possible. The
permissible total current must then be selected to be appropriately high
(p5509[5] > 70 %).
●
p3603 = 0 ... 50 %, p5507[3] = 8 ms, p5509[6] = 3 %.
● For operation on power grids with a stable frequency characteristic, for dynamic support,
a longer smoothing time for the PLL is recommended: p3458[1] = 50 ms.
Grid infeed
System Manual, 04/2015, A5E03347436A
status signals: r5502.1, r5502.2
adjustable parameters: p5505[0, 2], p5509[9, 10]
status signals: r5502.4, r5522.3
adjustable parameters: p5529[2, 3].
For weak grid conditions, which are typical for test laboratories, we further recommend:
7.10 Commissioning supplementary controls
Commissioning
135