From the best practices track-- #2

William Finn, Santee Cooper.South Carolina Public Service Authority. Power generators. 1st utility in SC to provide "green power" - electricity from landfill waste (methane)

Santee Cooper is using commercial off-the-shelf software to monitor controllable losses. These are losses an operator can reduce or eliminate through changes in the plant control system.

Santee Cooper uses OPC DA to get the latest process values, calculate controllable losses, and present their impact to operators.

OPC used to

  • Ensure a consistent high standard of environmental data
  • Automate manual plant processes currently in place using the Rainey Plant as a pilot
  • Reduce implementation costs by leveraging existing technology
  • Guarantee EPA-required 98% uptime in emission reporting.

Overall goal: OPC used to improve the bottom line.

Use OPC for turbine control. Vendor supplied the model and design, the maximum efficiency curves, but the reality is that plant is always operating in "off-design" conditions; thus we need real-time knowledge of system for comparison.

The traditional way to make these evaluations is to use rules of thumb and best practices.

Another reality is that plants have multi-vendor systems.

Multi-vendor control hardware means

  • No common data layer
  • Custom C drivers
  • Limited access to data.

Problematic because

No automation or connection between systems and inefficient operations.

Tools used to build the system:

  • Energy Balance Diagram of the turbine cycle
  • Performance Evaluation of Power Systems Efficiencies. (PEPSE) modeling software. Can see impact of various changes to system.
  • Table Curve 3-D
  • Visual Basic

PEPSI calculates heat rate for non-standard conditions: i.e., for a given load, vary the input, compute heat rate. Build model, but then feed in off-design conditions.

Use input from PEPSE. Import into Table Curve to create a table curve. Can put in what you actually operate and what you should operate at to see impact of changes.

Visual Basic snapshot of current condition using OPC DA (real-time). Picture of where you are right now.

Calculate "current condition" heat rate using the equation from Table Curve

Calculate "target heat rate" using the same equation

The heat rate difference is the impact.

Calculate cost of impact

Put impact and cost data into historian.

Gives system-wide knowledge of all process values, performance targets, impact cost savings.

Screens show actual values, best values (optimal), and actual money cost.

Benefits.

  • Efficient tools for operators and engineers
  • Easily sum the controllable loss cost for each KPI
  • Real-time trend displays
  • Data from the historian provides tracked accounting
  • Optimized maintenance schedule
  • Undiscovered data mining

Ten units running with this system. Future goal is to simplify the system even more. Limit number of vendors. Find system that will take less engineering/programming time to implement.

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