Virtual Flow Computer (VFC) application

Flow information obtained from meters at the pipeline terminals, the accumulated volume in particular, is critical to AVEVA Pipeline Operations for Liquids. Data errors and inaccuracies, either from the Remote Terminal Unit (RTU) or polling, can affect the Batch Transfer, Batch Tracking, and Pipeline Monitor (PLM) applications. The Virtual Flow Computer (VFC) application can provide validation and correction of this data before it reaches these applications. In addition, meters that operate in parallel to measure a merging of flow from multiple sources can have those measurements totaled.

Key Concepts

• Configuration data and runtime data for a meter is contained in the accumulator table.

• Configuration data and totalized runtime data for a set of meters operating in parallel is contained in the virtualflowcomputer table.

• The runtime data in the tables noted above provides an extension to polled meter data handled in the rate table (where data validation, volume correction, and flow totalizing is added).

Key Tasks

• Configuration for extended meter processing.

• Understanding the data generated for the meter.

• Using the Advanced Database Editor (ADE) for the VFC configuration.

The following diagram summarizes data flow for the VFC.

The diagram illustrates data processed as follows:

1. Volume accumulator (or counter) and flow rate is read from the rate table.

2. Temperature, pressure, density, differential pressure, and Mechanical Meter Correction Factor (MCF) is read from the analog table.

3. (Optional) The MCF can be read from the mtrfact table.

4. The VFC Processor validates, corrects, and totals the data to determine its own volume counter and flow rate values.

5. The VFC Processor saves its readings and computed values to the virtualflowcomputer and accumulator tables. Data in the tables is used in Controller screens and other applications.

6. Hourly throughput data is sent to the Historical inventory tables.