Development of a Backup Control System With a Serial Hydraulic Data Transmission System and a Subsea Multisensor System

Abstract

ABSTRACT A highly reliable control system for sub sea equipment had been jointly developed by Kawasaki Heavy Industries, Ltd. (KHI) and Japan National Oil Corporation (JNOC) from 1985 for 4 years. This system has a multiplexed electro-hydraulic system as a main control system and a serial hydraulic data transmission system as a backup control system. This Prim presents the following two subsystems and a device as part of the developed total control system shown in Fig. 1.Serial hydraulic data transmission systemSub sea multi-sensor systemUnderwater power generating unit INTRODUCTION As a backup control sys tern, a direct hydraulic System and a sequential hydraulic System are very popular in the sub sea control system for an offshore oil production. However the reliabi1ity of data transmitting capabilities is very poor compared with a main control system such as a multiplexed electro-hydraulic system. To improve the capabi1ities a serial hydraulic data References and i 1lustrations at end of paper. transmission system had been developed, which is an application of pressure propagation in pipe lines with pulse code modulation. A sub sea multi-sensor system had been developed by applying LAN(Lcml Area Network) technique and power 1ine carrier's technique. I t consists of analogue sensors, digital sensors, one loop data way (parallel two-core cable), inductive connectors and control unit, An underwater power generating unit had been developed to supply electric power to control pods when main electric power fed from a surface platform failed. This unit is driven by hydraulic w fed by hydraulic pumps located on the surface platform, The design conditions for this control follows, which are comparable to those offshore oi1 fields.Environmental conditionWater depth : 300mWater temperature : +0--35°CVibration : 2-13.2Hz ± 1m13.2--8OHZ 0,7GProduct ion conditionPressure :max.350kgf/cm2Temperature:0-100°CHydraulic fluidMaximum pressure : 210kgf/cfiWorking fluid : seawater based fluid or seawaterTemperature s ()-29°CElectric power in control podAC source : AC100V ± 15%, 60Hzf ± 10% 3 phase or single phaseDC source : DC 24V+20%-10% SERIAL HYDRAULIC DATA TRANSMISSION SYSTEM This hydraulic data transmission system was confirmed to lx applicable to a floating type production system by empirical tests with scale models.RequirementData transmitting between quite a distance is possible as several thousand inters via a hydraulic 1ine.Additional equipment and components are minimized in comparison with a sequential hydraulic SystemA Hydraulic power unit designed exclusively for operation of gate valves and choke valves can be uti1ized for generation of pressure waves without any modifications.