SystemOne via ARCNET®

HPI completed a flawless functional acceptance test (FAT) and installed a distributed control system (DCS) and supervisory control and data acquisition (SCADA) project for East Texas Electric Cooperative (ETEC). HPI worked closely with the customer’s consulting engineering firm, GDS Associates, Inc. to design, engineer, install, and integrate the systems at two sites for ETEC.

The HPI scope of work entailed design, engineering, manufacturing, and installation of plant-wide, redundant DCS utilizing an Allen-Bradley PLC ControlLogix™ platform. This system has a 100 megabit per second capacity and is suitable and expandable for balance of plant (BOP), data acquisition, performance calculations, sequential alarming, interlock logic functions, interfacing with combustion turbine controls, and interfacing with other plant sub-systems at two different sites.

Given the customer’s choice of maintaining GE Speedtronic™ turbine controls and an Allen-Bradley based DCS, a rather unique challenge was presented to the HPI team to integrate the two platforms via ARCNET. Since the GE Speedtronic turbine controls internal protocols are proprietary, a solution was needed that would meet or exceed the OEM’s standards.

Each of the two sites had two gas-fueled GE Frame 7EA turbines with GE Mark V Speedtronic turbine control systems and GE HMIs. Therefore, the HPI solution replaced the GE HMIs with one communication server per Mark V and one client, located in the main control room, to interface with both clients and to the plant control system over Ethernet. Each communication server connects to its assigned Mark V Stagelink (ARCNET) and they connect together over Ethernet to achieve full system redundancy. One communication server then serves as primary HMI for unit 1 and backup for unit 2. The other communication server serves as primary HMI for unit 2 and backup for unit 1. This is an enhanced, robust replacement for the Mark V and HMI operator interfaces supplied with Mark V turbine control systems. The system benefits are as follows:

  • Communicates with any Mark V over the existing Stagelink using standard off-the-shelf, non-proprietary ARCNET cards
  • Has all the functionality of the Mark V and HMI including control panel configuration and modification
  • Does not rely on IDOS, TCI, or Cimbridge
  • Does not require updating the Mark V PROMS
  • Minimizes operator training by replicating the existing operator screens

The new system has OPC servers providing a data interface for the FactoryTalk® system. A PI-compliant FactoryTalk historian is used at each site to capture, archive, and retrieve high-resolution, critical trip data from both Mark Vs.

Since HPI provides custom control systems, HPI was able to meet an uncommon customer requirement: To provide up to 100 sub-millisecond time-stamp digital points per site. This was accomplished through the use of SOE cards along with an integrated GPS module.