Belmont Pump Station Control Upgrades Modelling and Design
Problems have been experienced with its operation in Pressure Control mode, particularly delays in control system response and the choice of pump combinations used to meet existing conditions. This is most likely a result of its outdated control system as the expanding water network has grown more complex around it.
In 2017 the Water Corporation chose to redesign the control logic at Belmont Pump Station, based on experience acquired from the Water Corporation’s more modern variable-speed pump stations. It also aimed to implement a new Flow Control mode in addition to the existing Pressure Control mode, to achieve the daily water transfer rates required from the expanding Beenyup Groundwater Replenishment Scheme Stage 2, and for future ‘South to North’ water transfer scenarios.
From March 2018, One Stone Consulting reviewed and documented the existing control system for Belmont Pump Station and its operating requirements for not only the Beenyup Groundwater Replenishment Scheme but also current and future scenarios including ‘South to North’ water transfer from the IWSS Central System to Yokine Reservoir and/or Wanneroo Reservoir.
Various options for the control strategy for the Belmont Pump Station upgrade were then developed (PID control strategy, overrides, pump combination selection strategy, pump start/stop, pump and system protection).
Hydraulic and control system modelling was undertaken to assess the performance of each and select and develop the most suitable option. By incorporating the preferred control system model for Belmont Pump Station into an existing hydraulic model of the IWSS Central System, its design could be refined, the control strategy could be tested, and PID tuning parameters could be determined prior to commissioning. A Functional Description for the control system upgrades was prepared from this to outline the combination of control modes available (upstream/downstream pressure control, flow control) and to guide PLC programming, which was done by other contractors.
To test the PLC code for operational and contingency/failure scenarios prior to installation,
OneStone’s FluidSpace process simulation system was used to connect the programmed PLCs to the hydraulic model of the IWSS Central System. This effectively allowed the PLCs to control a ‘digital water’ version of Belmont Hill Pump Station and the IWSS Central System, delivering a hydraulically accurate feedback response from the connected system back to the controller in a real-time iterative loop.
The FluidSpace process simulation system was used to thoroughly test the PLC programming, the underlying control logic, and the control functionality programmed into the PLCs ‘offline’, prior to installation.
Commissioning and final live testing of the control system upgrades at the Belmont Pump Station was completed in July 2021.
Control system simulations done with FluidSpace were found to closely reflect the behaviour of the real system and no further tuning of the pump controllers was required. Live testing was completed in one day, with control of the pump station immediately returned to the Water Corporation.
The previous issues with Pressure Control mode were resolved, and Flow Control mode can now also be implemented at Belmont Pump Station to accommodate future water transfer scenarios.