Project Owner:
Southwestern Public Service Company, an Xcel Energy Company

Completion Date:
1997 (Unit 1), 1999 (Unit 2), 2003 (Unit 3)

The Harrington Station controls upgrade consisted of replacing existing boiler, turbine and balance of plant control systems for three 370 MW coal/gas-fired boilers and steam turbines. The new control systems are based around Foxboro I/A distributed control system (DCS) hardware and Woodward Governor and Siemens-Westinghouse turbine control subsystem.

The CRT-based operator interface is through a Utility Engineering (UE)-designed custom console that places the CRTs within easy reach and provides absolute minimum key-stroking for operator interface to all controls, alarms, data acquisition, sequence of events and burner management. UE also designed a unique window-box alarm presentation system which included “smart alarming” based on process conditions.

Automatic turbine start-up and loading is controlled by rotor stress calculations running in the DCS. This feature provides minimal rotor life expenditure during start-ups and load changes. The retrofit also included replacing most field devices; furthermore, the project included modifying the feedwater heater controls and extraction drains to meet ASME water induction protection guidelines.

Plant electrical distribution, including generator auto-synch and motor start-stop controls, boiler sootblowing, baghouse, flyash and water chemistry control, was included in the DCS. The project included installing a full fidelity simulator for engineering/checkout and operator training.

Services Performed:

• Planning/budget and schedule estimate
• Detailed BOP engineering
• Installation supervision
• Checkout, start-up and tuning
• As-built documentation
  

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