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      Subsea Control Systems

     Integrated Subsea Control Systems 

    For many years, a master control station (MCS) was used to control the Subsea Electronics Modules (SEMs) via the electro-hydraulic umbilical. The MCS was typically connected to the topsides DCS via a serial link (using, for example, Modbus protocol), which provided data acquisition from subsea sensors, and allowed control of valves.

    Over the last few years, however, there has been a movement towards the use of Integrated Control Systems, where the topsides control system communicates directly with the SEMs. This eliminates the requirement for a Master Control Station, which in most cases functioned only as a protocol converter.

    There are significant cost savings due to eliminating the Master Control Station, and there are technical benefits too:

    • Better integration with the topsides control system. There are many advantages, such as:
      • Standard function blocks can be used. The programming of the subsea logic uses the same methodology as the topsides.
      • Alarm processing is simplified. There is only one alarm system, with no duplication of alarms.
    • Simplified configuration. With an MCS and a DCS, two databases need to be maintained. With an Integrated Control System, there is just one.
    • Detailed SEM data. An many cases, an Integrated Control System provides detailed diagnostic data from the SEM that is simply not available via the MCS serial link, a case in point being with downhole gauges.
    • Simplified diagnostic capability. The engineer or technician can use a display at the ICS to perform diagnostics, without having to use the MCS or complicated SEM diagnostic software.
    Process IT's engineers have integrated the systems from two of the major subsea control suppliers into the Honeywell HPM:
    • ABB Seatec
      Originally developed for Norsk Hydro's Troll Olje project (North Sea, Norwegian sector), and subsequently used on Esso Blackback (Bass Strait, Australia)
    • Kvaerner FSSL
      Developed for Woodside Energy's Laminaria FPSO (Timor Sea)