Matthew Webb (Three Valleys) described the background to the staged implementation of on-line pump scheduling within Three Valleys, undertaken in parallel with the rationalisation of the Company and the centralisation of control facilities and associated SCADA systems. The work began with a desk-study review of operational practice including:
tariff analysis
identification of opportunities for energy optimisation
formulation of pumping schedules for immediate implementation
identification of system changes that would enhance optimisation savings
MISER-S had already been used for optimising operations over periods of one or more years, as well as evaluating capital schemes and operational strategies, and formulating a least-cost water budget.
The pump scheduling optimisation is for periods of 24 to 48 hours, for up to 7 days ahead. The area covered to date includes parts of West London and Surrey with 480,000 customers having an average total demand of 133 Ml/d. The annual energy bill for the area was in the region of £1.1M which will increase due to recent price increases.
Stephen Cook (Tynemarch) then gave an overview of the more detailed aspects of MISER-PS functionality. The software was installed in May 2003. Pump schedules are produced daily at 07:00, normally for the next 24 hours. System performance is tracked against the optimal forecast trajectories of reservoir levels, key flows, abstractions and demands.
There has been positive feed-back from the operations staff as follows:
optimisation results are directly applicable to daily activities
pro-active decision-support is valuable when operating under scenarios of high demand or educed plant availability
operations staff have the same goals even when working different shifts
there is less pressure to know the details of tariff structures
the MISER model provides a repository of network information which is helpful especially for new staff
Cost savings in the West London and Surrey in the region of £75k are expected, most of which will be achieved during the winter months when the demand is lower and there are more electricity peak periods. The next stage is to extend the coverage of the system to six other areas with a total energy bill of about £7.5M.
