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A control unit and a method for controlling a system comprising one or more devices

IP.com Disclosure Number: IPCOM000244590D
Publication Date: 2015-Dec-23

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention relates to a control unit (6) for controlling a system comprising one or more devices (1a‐b, 2a‐b, 3), each device having at least one control loop (4a‐f) for controlling the device based on a set point value (S1 – S5). The control 5 unit is adapted to receive measured values of system parameters of the system. The control unit comprises a simulator unit (8) configured to run simulations of the system based on a model of at least a part of the system, and to repeatedly during operation of the system predict the state of the system at a future point in time based on the received measured values of system parameters and current set 10 point values of the devices, and a control part (9) configured to determine new set point values for the devices based on the predicted the state of the system at said future point in time.

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251825A   

A control unit and a method for controlling a system comprising one or more devices   

Field of the invention 

The  present  invention  relates  to  a  control  unit  and  a  method  for  controlling  a  system  comprising one or more devices, each device having at least one control loop for controlling 

the device based on a set point value. The present invention also relates to the use of the  control  unit  for  a  subsea  production  system  for  producing  oil  and/or  gas.  The  present  invention  further  relates  to  a  subsea  production  system  for  producing  oil  and/or  gas  comprising a pump or a compressor and a control unit. 
 

Prior art 

Compressors and pumps are widely used devices in industrial systems. Compressors are used  to compress gases, and pumps are used to increase the pressure or flow of both liquids and  gases.  
 

In subsea oil and gas production systems a number of pumps are used. A subsea pumping  station  may  have  multiple  single  phase  and/or  multiphase  pumps,  valves,  separators  and  other system required equipment. The produced fluid from a main flow line is distributed  equally  for  each  of  the  subsea  pumps.  In  this  case,  each  pump  may  be  controlled  independently by its own control unit, often with a load sharing controller coordinating them. 

 

The  control  of  subsea  pumps  has  usually  been  very  simple.  Often  it  has  been  just  a  PID  controller  regulating  the  pressure  upstream  or  downstream  the  pump.  In  some  cases  the  speed of the pump is set directly from a control room in a connected topside installation, and  the speed is not changed very often. Some more complex pump control systems also exist, 

taking into account several real‐time parameters. In many cases the actual control systems  works well. In other cases the control of the system is sub‐optimal and leads to more wear  than necessary. Breakdowns may also happen because of sudden changes in the operating  conditions, or because the operators have not been aware of that the operating conditions  are outside what the device was designed for. 

 

Interventions on subsea oil and gas installations are expensive, and damaged equipment may  lead  to  production  losses  and  hence  big  losses  for  the  operators.  It  is  important  for  the  operators that the devices, such as pumps or compressors, installed on the sea bed, are as  reliable as possible, and that they are protected from operating conditions that may lead to 

unnecessary wear or damage. 
 

Hence,  conventiona...