A step-by-step guide to setting up a CENTAUR gate using RTC
By Dr Sonja Ostojin of EMS and Paul Campbell of Innovyze
On December 10th 2020 Innovyze hosted a Webinar with EMS and WSP looking at the virtues of the EMS CENTAUR™ system, what it is, how it can be applied and how it can be modelled using InfoWorks ICM.
CENTAUR™ is an intelligent, autonomous system for urban flood risk and CSO spill reduction. It senses the prevailing situation in the sewer network and uses fuzzy logic to decide whether to hold flow back or pass it forward. In this way, escapes are avoided or reduced. The technology fully leverages the capacity of existing infrastructure rather than building more.
Fuzzy logic RTC was added to ICM in v10.5 to allow CENTAUR™ real time controls to be accurately represented, bugs were solved in patch 10.5.2, so this is the earliest version of ICM which should be used for CENTAUR™ modelling.
This document is a follow up to the webinar to give a step-by-step guide to setting up a CENTAUR™ gate in ICM using RTC.
In the webinar, we used a simplified demonstration model where flows are generated at a subcatchments, flow down a steep sewer, at the end of which is a flow control with a CSO.
Figure 1: Demonstration model
To add a CENTAUR gate to the ICM, the first step is to add a VSGate link to the model to represent the CENTAUR gate.
To do this,
- Add a dummy node immediately downstream of the manhole where the gate is to be installed, splitting the link.
- Give the dummy node an appropriate name, set the flood type of the dummy node to sealed and the ground level equal to the manhole where the gate is to be installed. Also correct the length and the upstream invert level of the downstream conduit.
- Delete the short length of link between the gate node and the dummy node.
Add two new links between these nodes, one VSGate to represent the CENTAUR and one weir to represent the fail-safe weir.
The VS Gate is set up as shown in Figure 2.
- Invert level, and width are site specific.
- Opening height, maximum opening and discharge coefficients should be set to match the proposed gate.
- Gate depth is not used and should not be populated. This function is replaced in the model by modelling the fail-safe weir.
EMS recommend the regulator speeds and threshold to be set at the values shown, unless the details of the proposed gate are known from the design.
Figure 2: VSGate setup
The fail-safe weir is set up as shown in Figure 3.
- The crest level is site specific and must be at a level defined so as to protect assets upstream but will typically be at least 0.5 m below ground level.
- Width and discharge coefficients should be set to match the proposed weir.
Once the gate and weir are added, the RTC can be set up. The RTC for a simple one gate system requires six elements.
Figure 4: An overview of the RTC
- A range for the target location to be protected, (Figure 5). Which, in our example, we’ve called LMS1 at the CSO spill chamber. The target location range, LMS1, should have a minimum value set which corresponds to the level at which CENTAUR first comes into effect. For a flood location it should be around 0.5m below the ground level (to give time CENTAUR to react) or below the spill level for CSO.
- A range for the control location typically at the upstream node of the gate, always upstream from the target location to be protected, (Figure 5).
- Which we’ve called LMS2 at the chamber immediately upstream of the CENTAUR gate. The minimum level at LMS2 should be above the DWF peak but can be higher.
- An OR logic, (Figure 6).
- Which we’ve called Active. This defines when the CENTAUR control is active i.e. whichever of LMS1 or LMS2 minimum values is satisfied first.
- A CENTAUR controller, (Figure 7).
- Measurement Interval is measured in seconds and is representative of the control interval on the gate, it should always be modelled as a multiple of the simulation timestep. Measurement Interval should not usually be less than 60 seconds.
- Target range should be the range for the target location to be protected (LMS1).
- Gate range should be the range for the control location (LMS2).
- Target max (m AD) and Gate max (m AD) are site specific. Target max is usually ground level at a flooding site, or weir crest for a CSO. Gate max is generally above the fail-safe weir crest.
- Target change max (m/s) and Gate change max (m/s) are scaling parameters for the rate of change in water level, EMS recommend they should usually be set at 0.01 m/s.
- Min output (%) and Max output (%) are scaling parameters for the change in gate position on each control cycle. Min output = -50 and Max output = 10 should always be used with the CENTAUR controller.
- A default (open) rule.
- The default rule ensures the gate is fully open until either of the trigger ranges are reached.
- An “active” rule, (Figure 8).
- The “active” rule uses the CENTAUR controller to control the VSGate.
Finally, ensure the “override other control” box is unticked
Figure 5: An example of the ranges
Figure 6: An example of the OR logic
Figure 7: An example of the CENTAUR controller
Figure 8: An example of the Active rule
CENTAUR assumes the weir controls the maximum water level at all upstream points. However, in some cases, if there is a critical location upstream, additional rules may be needed. This can be done by adding standard RTC logic. To do this, an additional range is added setting a minimum water level at the critical location (e.g. LMS3). An additional controller is then be added which will override CENTAUR. This should be an incremental controller which should usually operate on the same time frequency as the CENTAUR controller. Finally, the override rule is added to open the gate by a set increment for each period where the critical location range is true.
Figure 9: Additional controls for a critical location