Control system for long distance water supply

Level Measurement & Control

June 2003 Level Measurement & Control Perimeter Security, Alarms & Intruder Detection

Due to the huge electrical power requirements for electrolysing aluminium ore, a Chinese aluminium refinery built their own power generator. The cooling water for the generator is supplied by 11 deep-water wells along the Yellow River, 10 kilometres away. Because of the long distance involved, a secondary pump station and a water reservoir were installed 1,5 km from the river.

A pump station was located 2 km further on from the secondary pump station and a second large water reservoir was installed on a high hill between the river and the refinery. All pumps and deposits are affected by seasonal problems and the primary pumps are submerged under water for the two months that Yellow River runs at flood stage.

The key to controlling the power generation's water supply is controlling the water level in the reservoir on the hill. The water level determines the on/off status of the second and third pump stations. The riverside pumps in turn depend on the water level in the secondary reservoir. This group of water valves and pump stations is controlled from the plant control centre. It monitors water, water pressure and the flow speed in the water supply, plus voltage and current in the power supply for the water system.

Traditional PLCs have difficulty meeting the demands of the control system in the harsh environment. The local system integrator reviewed both domestic and foreign suppliers before deciding on ProMicro's ADAM-4000M remote data acquisition modules and ADAM-5000 distributed data acquisition system.

The central control unit is located at the centre of the network and controls the secondary and third pump stations. Two Advantech IPC-610/P166 industrial controllers were installed for redundancy. The HMI interface is designed using Advantech's VisiDAQ software and provides historical trending generation.

The primary pump station uses ADAM-4000 modules for local data acquisition and control functions. Two ADAM-4510 repeaters are located at No. 1 and No. 6 pumps to ensure data transmission reliability in the long distance network. The advantages of the ADAM-4000 and 5000 systems are that the RS485 network's twisted pair wiring requirements are inexpensive and easy to build, remote and modular low-density and high density I/O module combinations contribute to making a flexible and cost-effective system and the system is more price competitive than PLCs.

Since completion of the water supply control system, the staff has had no need to travel back and forth between the river and the second and third pump stations. Pump on/off control takes place at the plant control centre and the supervisor can view the whole process on the monitor. The entire process operates automatically and saves labour costs.

For more information contact Elton Prytz, ProMicro, 011 706 7913, [email protected], www.promicro.co.za

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Control system for long distance water supply

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