Development of a System-Specific Diurnal Curve Using Available SCADA Information

Development of accurate Extended Period Simulation (EPS) hydraulic models requires the inclusion of a system specific diurnal demand curve that reflects the periodic change in demand throughout a full 24-hour period. Information on the diurnal variation of demands could be obtained directly from demand meters but typical systems don't have the appropriate metering equipment in place. Instead, actual demand in the system is often inferred from production information and the change in storage volume in the reservoirs in the distribution system. By setting the volume of demand during any time interval to be equal to the volume of water produced during that interval plus the volume of water leaving reservoirs minus the volume of water entering the reservoirs one can obtain an approximation of the daily diural curve that applies to all the customers in the system including residential, commercial, industrial, and wholesale. While this may appear to be a simple process, issues of daily variations in the diurnal curve and timing of when water from a source actually reaches the distribution system can complicate the calculations. This presentation discusses the issues involved in the need for and creation of a diurnal demand curve and presents a case study of the development of diurnal curves for a distribution system that considers winter and summer demands separately and evaluates the system-wide diurnal curve that includes all demand and a curve that removes wholesale customers from inclusion in the final curve.