Compressor Station Modernization

A major natural gas transmission company operates a 6,000-mile pipeline system from Western supply sources to its markets in the Midwest. The 24 compressor stations were based on sets of 1,000 to 8,000 hp reciprocating natural gas engines.

The operator wanted to modernize the stations by replacing he oldest engines with higher-horsepower Solar turbine compressor packages, which are more efficient and easier to maintain. They also wanted to upgrade the PLC-based process control systems, standardize the operator interfaces and gain the flexibility to operate the stations in unmanned mode.

SKW implemented the project in two phases for each station: integration of the new Solar turbine compressor packages with the existing system and PLC programming to support upgraded controls and unmanned operation, plus configure operator interface displays with a standard look and feel using Wonderware InTouch.

During Phase I, the project team brought turbine status from the Solar Allen Bradley ControlLogix PLC into the station controller via Modbus digital communications and were implemented for remote turbine monitoring from the Houston central control.

The Phase II upgrade condenses the functions of multiple area PLCs into a single Siemens 505 station controller. The new PLC architecture results in fewer programs which are easier to maintain and reduces spare parts inventory. The process application was reprogrammed for more efficient control.

Capacity control algorithms and Maximum Allowable Operation (MAOP) set points were modified for the new turbines and optimized for the existing engines. Remote set point and command control logic allows for unmanned operation via microwave communications with a Telvent DCS in Houston.