Ensuring Optimal Water Management

MISER

2 MISER software

MISER

MISER-WRM Surface water yield

assessment

MISER-S Production planning

MISER-PSL On-line pump

scheduling

MISER-SI Optimal scheme

Selection

Sub-Daily Extension

Probabilistic Inflow Sequence Generator

Source Tracker Extension

MISER-PS Off-line pump

scheduling

MISER is a highly configurable and flexible suite of decision-support tools for optimal water management, asset and resource planning.

MISER is designed to identify the minimum cost operation of water resource and supply systems, whilst satisfying demands and ensuring compliance with user-defined performance constraints.

MISER enables the user to optimise system operation over a wide range of time horizons in a single step, avoiding the need to pre-judge the timing of specific abstractions or releases.

MISER is in daily use by water industry professionals to solve a wide variety of operational and investment planning problems.

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Key features include:

Single modelling solution for both short and long-term analysis Simulation and optimisation Fully user-configurable options Schematic and menu-driven interface Extensive range of constraint types and

modelling facilities Robust multi-objective optimisation Step-by-step or whole horizon optimisation Multi-user access via MS SQL Server Supported by experienced analysts Customisable

Anglian Water

United Utilities

South East Water

MISER is in use by 13 water companies in the UK

for a variety of applications:

production planning

pump scheduling

emergency response management

outage analysis

behavioural simulation

deployable output assessment

supply-demand analysis

optimal scheme selection

4 MISER software

Monthly Production Planning

A common application of MISER is monthly production planning and water budgeting to plan source outputs, reservoir levels and key transfers over the medium-term, taking account of influences such as:

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Expected demand Potential droughts

Planned outages Licence availability Future licence changes Target reservoir levels Groundwater levels Water quality Operating costs

MISER-S is the standard package, operating over a range of time steps (e.g. daily, weekly, monthly) with horizons from 1 day up to many years.

MISER-S can simulate the operation of complex systems using pre-defined control rules, including running against different historical streamflow years.

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MISER-S can be used to generate operational control curves automatically, specifying minimum reservoir levels in order to maintain given levels of output. For example, it has been used to develop control curves for the Jersey Water desalination plant across a range of system yields to identify the conditions under which this resource should be used.

A problem with pre-defined rules is that they tend to result in excessively costly or risky operation, as they are based on one variable alone (reservoir storage or licence usage) and take inadequate account of other factors such as the prevailing level of demand, river flows, groundwater levels and source outages.

To address this issue, in addition to simulation MISER-S can optimise globally over the whole time horizon. This maximises savings and security of supply through selection and timing of resources, and is an essential aspect to ensure best use of reservoir storage and annual licences. Strategic optimisation studies have demonstrated potential electrical and chemical savings of 8-10% pa for a number of UK water companies.

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MISER handles multiple user-configurable optimisation objectives and can consider each in turn or in combination, e.g. meet demand, refill reservoirs then minimise cost. Objectives can be prioritised, for example to model works emergency capacities which can only be exceeded in order to meet high demands.

Minimisation of cost is one of MISER's key objectives, taking into account all costs between source and tap. Fixed costs and volumetric costs are supported, including volumetric costs which vary with flow.

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Water Resource Modelling

MISER has been applied to a wide range of water resource studies including:

Control rule development Deployable output assessment Analysis of drought restrictions Reservoir storage projection Maximum yield under conjunctive use Simulation of canal hydrology Lumped leaky aquifer groundwater modelling

The MISER-WRM extension to MISER-S includes the Water Resources Module for derivation of surface water deployable outputs under specified Levels of Service.

In addition, MISER includes a probabilistic inflow sequence generator for generation of synthetic inflow sequences that have formal significance (e.g. 1 in 100 years return period). Statistical distributions are automatically selected and fitted to streamflow data. The cost of operation associated with different non-exceedance probabilities can be quantified to provide decision-support when balancing risk and cost.

August Flows Histogram & Fit

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) Drought control measures such as demand restrictions and licence reductions at low reservoir levels can be modelled, and MISER-WRM identifies the maximum demand which can be supplied for given frequencies of occurrence (e.g. no more than 1 in 80 years).

MISER-WRM can also carry out flow duration and frequency analysis on user-entered streamflow data.

6 MISER software

Pump Scheduling

MISER was first installed as an on-line pump scheduler at Thames Water in 1988, where it ran continuously for more than 8 years generating recognised savings of 8-10% pa. More recently, there has been a renewed industry interest in pump scheduling as a result of increasing energy prices. On-line pump scheduling using MISER is now implemented in Anglian Water, and closed loop control using MISER is implemented in the Warminster area of Wessex Water.

MISER-PS generates pump and valve schedules, taking into account pump performance and electricity tariffs, primarily for cost and energy savings. Constraints can be applied to ensure compliance with licences, water quality constraints, yields, storage limits, minimum/maximum flow requirements and so on. Results from MISER production planning models can be used to provide longer-term operating ‘envelopes’ within which the short-term operation must comply, to take account of raw water availability and annual licences.

Off-line, MISER-PS is used to derive operational guidelines for pump scheduling, plan maintenance and compare electricity tariffs.

On-line, MISER-PSL extracts data from corporate telemetry/SCADA systems for automatic routine generation of pump schedules, providing the benefits of reduced manual input, demand forecast-ing, higher cost savings, and improved security of supply through pro-active management of the system and rapid response to outages.

MISER-PSL can be used in a Control Room

to:

Validate and replace poor quality telemetry data

Provide visualisation of the supply system together with flows, reservoir levels and demands from telemetry

Forecast short-term demands Optimise operation against forecast

demands Generate schedules for uploading into

SCADA for automated closed-loop control.

A phased implementation is recommended as pump scheduling can introduce major changes in company culture. An initial phase might involve generation of off-line schedules to assess cost-savings and identify any quick-wins, which may be followed by on-line and automated control implementations in a trial area to develop system requirements and demonstrate benefits.

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Investment Planning

MISER has been used extensively to model the consequences of outages for capital maintenance planning, by optimising management of a system during a failure (maximising the delay before any customer is affected and minimising the number of customers affected).

Demand Deficit Over Time

Additionally MISER can track the flow of water through the network to identify populations which might be affected by a source contamination incident.

Other related applications of MISER-S to investment planning include:

Analysis of the supply-demand balance at a zonal and nodal level Identification of bottlenecks in the network preventing demand from being met Optimisation of the sizing of new assets to meet demand

A key feature of long-term planning using MISER is that the same base model can be used as for short-term planning, thereby all the benefits of the model are available, model maintenance is simplified and a consistent approach is ensured.

The MISER-SI extension augments the optimisation capabilities of MISER to include selection of investment.

Multiple user-defined supply-side and demand-side schemes can be specified and MISER-SI will determine the optimum set of schemes to be undertaken, their phasing and how the supply system should be operated to ensure adequate supply-demand balance at minimum NPV cost.

MISER-SR2 incorporates Monte Carlo simulation to take account of uncertainty in investment forecasts. Optimisations are performed over many trials in which demands and inflows are sampled from user-defined statistical distributions.

Distributions of optimal results are produced which show how costs, supply-demand balance, abstractions and so on vary with input uncertainty.

References 1 Henriques and Fowler (2009), 'Case study in resilience analysis and scheme selection', CCWI 2009. 2 MISER-SR is currently at a prototype stage of development.

Wessex Water applied MISER-SI in its least-cost planning using a regional model, with inter-dependent schemes including leakage options balanced against new resources, and incorporating simultaneous analysis of peak and average conditions.

For example, Anglian Water modelled individual and multiple site failures resulting from widespread flooding. The approach provided "auditable and objective results, suitable for inclusion in company business plans and consistent with Regulatory requirements"

1.

Making the most of MISER

Tynemarch work directly with our MISER users to provide support for model building and calibration.

We will help solve unusual problems and encourage innovative use of the extensive

functionality available in MISER.

We focus on assisting our users to obtain the maximum benefit from using MISER to maintain

supplies at minimum cost, identify the most cost-effective investment programmes and ensure

optimal utilisation of the entire water resource and supply system.

Spring Court Station Road

Dorking, Surrey, RH4 1EB tel: 01306 742772 fax: 01306 742276

email: sales@servelec-technologies.com website: www.servelec-technologies.com