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equipment

PanelView PV600 Model #2711-K6C5 (DH-485)


PROJECT: Gas Compressor Control Logic Upgrade Project


A Southern California Independent Power Producer (IPP) owned a number of simple cycle natural gas fueled "peaking" units three of which were sister units spread strategically in this southern region. All three plants had a common problem with their respective natural gas compressors.

These three plants were built during the energy crunch of 2002 thus they were fast tracked with all the other new California generation coming online at the time. A consequence for this type of generation was a short supply of readily available gas compressors for all the new gas turbines. The original builder of these plants found a supplier that had somewhat new compressors available and the compressor skids with their respective control systems were quickly assembled without testing and shipped to the site. Attempts during the startup and commissioning phase of the original construction were not successful at getting these compressors operational but the local gas pressure from Southern Cal Edison was sufficient to operate the turbines to full capacity without the use of the gas compressors.

Recent major changes by Southern Cal Edison threatened to lower the gas pressure thus requiring the IPP to overcome the problems with commissioning the gas compressors. Engineering services was initially sent to assess the control system logic, instrumentation, and overall operation of each system. This assessment resulted in a project to abandoned the original control logic and design, install, and commission new ultra-stable logic and upgrade the operator Human Machine Interface (HMI) consoles.

An additional side project was to verify all the instrumentation devices used within the control system's input/outputs. The engineering services included management of a control technician who performed the instrument checks. The management responsibilities also included those typical to a Project Manager; weekly status reports, providing a schedule in MSProject, and a full cost report.

RESULTS


• Designed extremely stable fully automated pressure control logic for tandem gas compressors in a lead/lag strategy incorporating the loading solenoids and bypass valves as the trim control. The design was documented as SAMA functional drawings.

• Designed & converted the full analog and digital (SAMA & Boolean) functional logic as drawn up in Microsoft Visio to the equivalent functionality using Allen-Bradley's ladder logic. This was a major conversion of block logic to ladder logic achievement.

• Created, developed, and programmed all the operator graphics (including alarm screens) for full operation of the gas compressors. Successful in the use of the A/B software, PanelBuilder32 to complete this achievement.

• Completed a successful startup and commissioning of the upgraded control system for all three client's sites of gas compressors. This client was very pleased with exceeding expectations on control stability and compressor reliability.