PWSC was formed in 1983 to provide specialist consulting services associated with the operation and development of water resource, water supply and electricity supply systems.
Rising demands, and the threat of greater stream flow variability as a result of climate change, continue to heighten recognition that water is becoming a progressively more valuable and finitely limited resource. Coupled with growing economic, environmental, and regulatory pressures, it is therefore imperative that systems used to supply water and electricity be operated as efficiently as possible. For systems of any complexity, optimizing their long and short-term operation, as well as their future development, increasingly requires the application of advanced analytical techniques.
To address perceived short comings in commercially available software PWSC has, over the years, developed a number of computer programs for optimising the long and short term operation of such systems and their expansion, and these have been successfully applied to major systems in the United Kingdom, Asia, Africa and South America. Continuing advances in computer technology and mathematical optimisation algorithms have now resulted in PWSC's development of the two computer programs outlined below and capable of delivering significant financial benefits in terms of reduced operating costs, increased supply reliability and improved decision making.
has been developed to optimise the long and short-term operation of water and electricity supply systems of considerable size and complexity, while providing facilities for the seamless display and analysis of results. Special features include:
- the detailed modelling of inter-dependent water resource, water supply and power supply systems required to satisfy multiple water and electricity demands while subject to a range of technical, environmental and commercial constraints;
- the on-screen definition of the system configuration to be modelled, and the input or modification of associated data via component specific templates;
- robust Linear Programming algorithms for optimising system operation within each daily, weekly or calendar monthly simulation time-step;
- a stochastic Dynamic Programming algorithm for optimising stationary long-term operating policies;
- the storage of detailed simulation and optimisation results in Microsoft ACCESS© database format and provide exceptional modelling transparency and facilitate regulatory audit;
- 'real time' graphical screen displays of system behaviour, the 'playback' of simulation results in 'mimic' diagram form, and the display and high definition printed output of time series.
can be applied to water resource systems used for water supply or the generation of hydro-electricity, or both, and its potential applications include:
- simulation of system performance over 'historic' inflow sequences based on existing operating policies;
- assessment of 'firm' (reliable) water yields and electricity production;
- optimisation of long-term system based operating policies, including energy trading
- evaluating the potential contributions of development options
- optimising short-term operation, i.e. up to seven days ahead, based on forecast inflows, demands and, if applicable, wind speeds, and encompassing energy trading and flood control
has been developed to optimise the expansion of power supply systems and overcome major limitations associated with existing software, including the inability to: model multiple electricity demands and transmission (load flow) constraints; guarantee the optimum selection and introduction of hydroelectric plants; and cater for project interdependencies and budgetary constraints. The program consists of an Optimisation Module and a Simulation Module, which share a common set of data input files.
The Optimisation Module employs Mixed Integer Linear Programming (MILP) to simultaneously optimise the selection and scheduling of generation plant and transmission lines, as well as import and export quantities while taking explicit account of project interdependencies, demand management and budgetary constraints. The objective function to be minimised includes the total investment and operating costs incurred over the specified planning period, and the throughputs of each generation plant and transmission plant are optimised for each annual or monthly interval, load block and 'hydrological condition'. The Simulation Module also uses Linear Programming to determine the least cost load dispatch in each month of a defined expansion plan, as produced by the Optimisation Module or as constructed interactively using on-screen menus.
Both modules can take account of constraints on generating plant outputs, transmission load flows and carriage costs, transmission losses, and demand dependent supply benefits and deficit penalties. Deterministic or probabilistic simulations can be performed using the Simulation Module, and operating cost estimates provided for renewable energy plant outputs associated with up to 5 'hydrological conditions'.
provides extensive facilitates for: the display of detailed and consolidated results in graphical and tabular form, and their export in CSV output files; Microsoft ACCESS© format database storage of alternative expansion plan evaluation results, system component details and electricity demands; and the 'mimic' diagram display of system development and load dispatch results as a function of monthly step, load block and 'hydrological condition'.
In addition to expansion planning, potential applications include import and export tariff negotiations, internal tariff setting based on long-term marginal costs, and the comparison and selection of project variants in the context of the recipient system.
Both programs have been specifically designed to take account of the variable availabilities associated with wind and solar renewable energy plants. Detailed descriptions and on-line demonstrations of both programs can be provided on request.
PWSC is active in the United Kingdom and overseas, and has particular experience in Asia, Africa and Latin America. It is independent of any contracting and manufacturing interests.