Document Type
Presentation
Publication Date
8-1-2014
Abstract
Real-time hydraulic and water quality modeling involves the modification of the EPS network model every few minutes to reflect the SCADA data, and this paper shares how this type of real-time modeling framework, HydroTrek, was built on top of the EPS foundation provided by the EPANET toolkit. The real-life applications of HydroTrek posed some interesting modeling challenges when the hydraulic time-step was reduced to match the SCADA time-step of one to five minutes. For example, a physical pump usually does not instantaneously, but a model pump does. In a sensitive network, that can mean a significant mismatch between the SCADA and model tank demands, and consequently in the modeled tank levels. If the real-time model is updated by discarding ‘all model rules’ and strictly run on the basis of the SCADA component status values, then the tank level discrepancies can get further exacerbated through the "opening" or "closing" of valves that influence these tanks . Some systems also operate multiple valves in parallel in a lead-lag configuration and switch the active configuration in a manner that can’t be represented in an EPS model. Increasing the hydraulic time-step can reduce the ‘hydraulic’ problems but has the unfortunate consequence of masking the water quality spikes which are important for anomaly detection and for reduction of false positives in contaminant warning systems. Also, an EPS model may represent a battery of pumps with a single pump curve and may include simple tank mixing, and those may not be sufficient for real-time modeling. The authors conclude that although the EPS toolkit behaves well through the major portion of the real-time simulation, further hydraulic and water quality modeling advances and refinements are needed to improve the match with SCADA data.
Comments
Session S1-02, Special Symposium: Real-time Simulation Modeling in Urban Water Systems