A variable speed pump battery (VSPB) element represents a set of identical parallel variable speed pumps which can be controlled to provide a fixed head or fixed flow or follow a time pattern of speeds. This type of element is only available with the GVF-convex solver. See“Variable Speed Pump Battery” for details.

The behavior of a VSPB in cannot be captured with the GVF-rational solver if the pump is operated any way other than inflow matching outflow. However, there are ways of mimicking VSPB behavior in the dynamic wave implict (DW) and explicit (SWMM) solvers using the “Depth-Flow (Variable Speed)" (Type 4) pump in the pump definition. For example, suppose that a variable speed pump station with several pumps is operated to maintain a wet well depth of 30 in. (outflow matching inflow), and the normal inflow is roughly 0.5 cfs and the maximum the station can pump is 2 cfs. The table of flow vs. depth in the pump definition might have values like the ones below. The final point should correspond to the maximum pump battery flow at the maximum wet well depth. It is advisable to cover the full range of wet well depths.

VSPB Pump Definition

As soon as the inflow deviated from the previous value, the depth would change and the outflow would respond.

If you want to switch between the GVF-convex and either SWMM or DW with a VSPB, a different active topology must be used for the two types of models. Create an active topology which contains a VSPB for GVF-convex scenarios and one which contains a pump that simulates a VSPB for SWMM and DW scenarios. The model should look something like the image below, which shows the case where the VSPB is inactive.

If there is an active VSPB element in a solver other than GVF-convex a fatal error message is issue and the run does not proceed.