POWER INTERFACE COMMUNICATION

Description

[0001] The present invention relates to communication between a subsea control system and one or more actuators or auxiliary equipment at a subsea environment. In particular, but not exclusively, the present invention relates to a communication over powerline technique for electrical actuation of auxiliary equipment within a subsea control system.

[0002] US 2014 / 015449 A1 discloses an electric control and supply system. GB 2 352 376 A discloses a telemetry system in which data signals are modulated on power signals.

[0003] Within subsea controls there is a market drive to reduce CAPEX and OPEX, reduce infrastructure complexity, improve diagnostics, enhance command and control, improve reliability, improve availability, increase safety and reduce environmental impact of the controls solution.

[0004] There is a perception that this can be achieved by providing system solutions, which utilise partial or full electrical actuation, rather than the incumbent technology which utilises electrohydraulic actuation. Various auxiliary equipment needs actuation. One possible type of auxiliary equipment is a control valve.

[0005] Although beneficial, electrical actuation has proven CAPEX prohibitive when compared to electrohydraulic system solutions.

[0006] One contributing factor is the required quantity of electrical interfaces between the control system and the actuators to deliver the necessary control. The associated quantity of electrical connectors, junction boxes and the pin count of connectors introduce notable cost, complexity and the potential to impact system reliability when compared to hydraulic actuation interfaces.

[0007] It is an aim of the present invention to at least partly mitigate the above-mentioned problems.

[0008] It is an aim of certain embodiments of the present invention to reduce the connection member (e.g. pin or socket) count at wet mating connectors used to provide power and / or communication signals to auxiliary equipment or valve actuation modules.

[0009] It is an aim of certain embodiments of the present invention to provide apparatus and a method that utilises only a Live 1 (L1) or Live 2 (L2) input signal over a wet mating connector to provide power and control communication for an actuator of a subsea valve or auxiliary equipment.

[0010] It is an aim of certain embodiments of the present invention to provide in built redundancy as well as reducing electrical connection member headcount that includes only two sets of L1 and L2 inputs for motor drives for a subsea valve actuator.

[0011] It is an aim of certain embodiments of the present invention to provide communication over power system (COPS), often referred to as a Powerline System (PLS), for example broadband over powerline (BPL) or other such power line signalling techniques, via a power cable connection to auxiliary equipment or actuators, such as a control valve actuator acting on a master valve or pilot valve, in a subsea environment.

[0012] The present invention is defined by the attached independent claims. Other preferred embodiments may be found in the dependent claims. The present application discloses a subsea system, comprising:at least one valve actuator module (130); and at least one modem unit (210) that receives power signals;a housing; characterized by at least one wet mating connector (140), comprising at least one connection member (200) on an outer surface of the housing and connectable to a power cable that receives the power signals; and the modem unit (210) is in the housing and is connected to said at least one connection member (200); wherein at least one auxiliary equipment (100) is responsive to an output provided by the modem unit (210).

[0013] Certain embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which: Figure 1illustrates an electrical actuator for a subsea valve; Figure 2illustrates a subsea actuator with COPS e.g. BPL interface; Figure 3illustrates a greenfield site; and Figure 4illustrates a brownfield site.

[0014] In the drawings like reference numerals refer to like parts.

[0015] Figure 1 illustrates subsea auxiliary equipment 100 in the form of a valve. It will be appreciated that certain embodiments of the present invention are applicable to the control of different types of auxiliary equipment. The valve 100 is driven by a drive element 110 via a mechanical interface 120. The mechanical interface 120 is part of an electrical actuator with Communication Over Powerline System (COPS) interface 130. An electrical interface is made via a wet mating connector 140 which can be secured to a releasable connector 150 that carries a power cable 160.

[0016] Figure 2 illustrates the electrical actuator with COPS interface 130 in more detail and illustrates how the wet mating connector 140 includes four electrical connection members in the form of pins 200. Four pins are utilised because the interface includes in built redundancy. Two pins 200 1,2 are used for respective Live 1 (L1) and Live 2 (L2) power input signals that are received from the power cable 160. Two remaining pins are utilised for respective Live 1 and Live 2 signals also carried by the power cable 160. As part of a power line modem unit, a diplexer 225 extracts communication data from the incoming signals from the respective pair of electrical connection members. A power line modem 210 is in the housing of the valve actuator module 130 and provides control signals to the respective motor drive A. A further modem 210 operates in a similar manner to provide control signals to motor drive B. A power conversion unit 255 converts the power signal extracted by the diplexer 225 and provides power signals to the power line modem 210, a controller and telemetry acquisition unit 245, and a motor drive unit 290. A communication and feedback unit 265 provides angular position data to the controller and telemetry acquisition unit 245. If present, a linear variable differential transformer 280 provides linear position sensor data to the controller and telemetry acquisition unit 245. COPs signal supply pin for redundancy sub-system 'A' (200 1 ) COPs signal return pin for redundancy sub-system 'A' (200 2 ) COPs signal supply pin for redundancy sub-system 'B' (200 3 ) COPs signal return pin for redundancy sub-system 'B' (200 4 ) Diplexer (225) COPS input separated out into separate power (output) and communications (input output) via passive filter elements. Power passes through (with minimum attenuation) a Low Pass Filter (LPF) and a Communications Blocking Filter (CBF) to the motor drive. CBF presents a high impedance to the communications signals and prevents loading of the communications drivers by the motor drive input impedance. CBF attenuates the communications signal frequency components of the COPS signal so that (predominantly) only power is delivered to the motor drive. CBF prevents conducted emissions from the motor drive (that are within the communications pass band) from propagating back onto the COPS line. Communications pass through a High Pass Filter (HPF) or Band Pass Filter (BPF) and Communication Isolation Transformers (CIT) to the modem front end. BPF presents a high impedance to the power frequencies and attenuates the power waveform and associated harmonics of the COPS signal so that only (predominantly) communications are delivered to the modem. BPF is bi-directional, enabling: Communications to pass from the COPS line to the modem receiver Communications to pass from the modem transmitter to the COPS line PLS Modem (210) Communications device capable of receiving and transmitting modulated communications signals via a power line signaling system. PLS Modem Chip Set (230) ∘ This is a modem chip set that controls data flow. PLS Modem Front End (235) Robust modem transmitter and receiver interface circuitry incorporating filter functions and enhanced conducted emissions immunity so that the modem is tolerant of the noise and transients associated with COPS / PLS applications and motor drive applications. Controller and telemetry acquisition (245) Unit capable of the following: Communications control Modem interfacing and management Topside command interpretation Motor / actuator status monitoring Sensor telemetry formatting, packetisation Actuator Motor Drive control Motor sensor signal conditioning and interpretation Motor telemetry acquisition and interpretation Temperature, vibration (accelerometers), pressure within actuator pressure isolated enclosure Power Conversion (255) Unit capable of converting either DC or AC power as delivered to the actuator into various forms as required for actuator operation including but not limited to: Motor drive power Modem power Controller power Motor Commutation Feedback (265) Angular position sensors housed within the motor used to determine rotor position and subsequently used by the motor controller as part of a feedback motor control loop. Gearbox (275) Torque multiplier for rotary drives Or converters rotary gearbox output into a linear drive for linear displacement actuator(s). Linear Variable Differential Transformer (280) Position sensor used for linear as opposed to rotary valve actuators (shown in dashed detail as device will only be fitted for linear actuators) Motor redundant windings (285) Motor windings to facilitate independent A and B function control and drive of the electric actuator. Mechanical Interface to Valve (Stem) (120) Linear or rotary mechanical interface to a valve stem to facilitate valve opening and closing. Motor Drive (290) Electronic motor that drives gearbox.

[0017] Figure 3 illustrates an electrical actuator system at a greenfield site utilising communication over powerlines system (COPS). Communication signals pass from an umbilical termination assembly (UTA) 300 to a subsea SCM or PCDM communications converter unit 310. Power signals pass from the UTA 300 to a subsea SCM or PCDM power conversion unit 255. Input and output communication can occur between the communications converter 310 and a power line modem 210. A COPS signal is formed from the converted power and communication signals by a diplexer 225 and is transmitted to a junction box 330. Electrical actuators are multidropped from the junction box 330 and receive the COPS signal through a wet mating connector 140. Umbilical Termination Assembly UTA (300) As ordinarily understood by the skilled person. Communications Converter (310) ∘ Converts communications data passing between a PLS modem 210 and a UTA or a platform 400 to appropriate communication standard for transmission across appropriate interface standard. Power Switch (320) ∘ As ordinarily understood by the skilled person. Junction Box (330) ∘ Electrical interface that facilitates multi-dropping functionality between any SCMs, PCDMs, actuators, or auxiliary equipment mutually connected to same junction box.

[0018] Figure 4 illustrates an alternative electrical actuator system at a brownfield site utilising communication over powerline system (COPS). Figure 4 is in many ways similar to figure 3, except a COPS signal is formed topside and is transmitted subsea to a junction box 330 via a UTA 300. Platform (400) ∘ This may be a floating facility, or a topside vessel, or a topside rig, or an onshore facility.

[0019] Aptly a COPS modem is installed within the control system located subsea, i.e. within a Subsea Control Module (SCM) or Topside within the Master Control Station (MCS). A further modem is required within each subsea actuator completing the communications link between the actuators and the control system. The modems providing the command, control and communication interface between the actuators and the control system.

[0020] The COPS modem provides tolerable bandwidth for limited diagnostics and adequate command and control which help to satisfy the drive for reduced OPEX. By locating the COPS modem within the actuator, the aforementioned can achieve adequate control whilst keeping the connector and pin count associated with the electrical interface to an absolute minimum. More than the absolute minimum could of course optionally be used. By contrast achieving command and control using traditional interfaces such as Fieldbus i.e. Industrial Ethernet, Modbus or Canbus, with separate power conductors would result in a proliferation of connectors, pin count and junction boxes. This would negatively impact system cost and reliability.

[0021] Direct actuator command and control is possible utilising COPS Modems over only the power supply from a solely topside control system. The available communications bandwidth would further be reduced and at least partially depend on offset to the subsea actuator from the topside control system. The performance and capability of such a system would largely depend on offset.

[0022] In a system where the communications from topside to subsea structures, such as Manifolds or Trees, is via high speed Digital Subscriber Line or Optical Fibre. COPS becomes beneficial as the offset from the control system's high-speed backbone to the electrical actuators located on the structure is short (in the order of tens of meters). It is therefore possible, over COPS to achieve tolerable communications bandwidth which is suitable for limited diagnostics and adequate command and control, whilst keeping CAPEX associated with the electrical interface to a minimum.

[0023] COPS has advantages over other communication technologies as command and control is feasible without the need for a dedicated communication bus or point to point communication interfaces from the control system to the actuators.

[0024] As an alternative embodiment a COPS modem is installed within the control system located subsea, i.e. within a Subsea Control Module or Topside within the Master Control Station. A further modem is required within each subsea actuator completing the communications link between the actuators and the control system. The modems providing the command, control and communication interface between the actuators and the control system.

[0025] The COPS modem provides tolerable bandwidth for limited diagnostics and basis command and control which helps to satisfy the drive for reduced OPEX. By locating a BPL modem within the actuator, the aforementioned can achieve adequate control whilst keeping the connector and pin count associated with the electrical interface to an absolute minimum. By contrast achieving command and control the using traditional interfaces such as Fieldbus i.e. Industrial Ethernet, Modbus or Canbus, with separate power conductors would result in a proliferation of connectors, pin count and junction boxes. This would negatively impact system cost and reliability.

[0026] Direct actuator command and control is possible utilising BPL Modems over only the power supply from a solely topside control system. The available communications bandwidth is at least partially dependent upon on offset to the subsea actuator from the topside control system. The performance and capability of such a system would largely depend on offset.

[0027] In a system where the communications from topside to subsea structures, such as Manifolds or Trees, is via high speed Digital Subscriber Line or Optical Fibre. BPL becomes very beneficial as the offset from the control system's high-speed backbone to the electrical actuators located on the structure is short (in the order of tens of meters). It is therefore possible, over BPL to achieve and exceed the necessary communications bandwidth for improved diagnostics and enhanced command and control, whilst keeping CAPEX associated with the electrical interface to a minimum.

[0028] BPL has advantages over several existing communications over power lines technologies in that it is possible to achieve much higher data rates over comparable distances allowing for improved diagnostics and enhanced command and control of the actuators to be possible. These enhancements are also feasible without the need for a dedicated communication bus or point to point communication interfaces from the control system to the actuators.

[0029] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to" and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Claims

1. A subsea system, comprising: at least one valve actuator module (130); and at least one modem unit (210) that receives power signals; a housing; characterized by at least one wet mating connector (140), comprising at least one connection member (200) on an outer surface of the housing and connectable to a power cable that receives the power signals; and the modem unit (210) is in the housing and is connected to said at least one connection member (200); wherein at least one auxiliary equipment (100) is responsive to an output provided by the modem unit (210).

2. The subsea system as claimed in claim 1, wherein: the valve actuator module (130) comprises at least one actuator (120) for actuating the auxiliary equipment (100) wherein the actuator is responsive to an output provided by the modem unit (210).

3. The subsea system as in claim 1, wherein: the valve actuator module (130) is releasable.

4. The subsea system as in claim 1, wherein: each connection member (200) comprises a single pin or single socket of the wet mating connector (140).

5. The subsea system as in claim 1, wherein: the wet mating connector (140) comprises four or less connection members (200).

6. The subsea system as in claim 1, wherein: the wet mating connector (140) comprises two connection members (200) or four connection members (200).

7. The subsea system as in claim 1, wherein: the valve actuator module (130) comprises a single wet mating connector (140) connectable to a single power cable.

8. A communication system for determining operation of the at least one actuator (120) of the subsea system of claim 2, the communication system comprising: the at least one actuator (120) arranged to operate responsive to a motor drive unit (280) to thereby determine a state of the auxiliary equipment (100) disposed at a subsea location; a power line modem (210) in the housing that houses the motor drive unit (290) and that provides a control signal that determines operation of the drive unit (290); and the at least one wet mating connector (140) of the housing including a plurality of electrical connection members (200).

9. The communication system as in claim 10, wherein; the wet mating connector (140) comprises only two connection members (200) or only four connection members (200).

10. The communication system as in claim 10, wherein; only a positive supply contact and a return supply contact for each motor drive unit (290) in the housing are provided at the wet mating connector (140).

11. The communication system as in claim 10, wherein; the control signal from the power line modem (210) is connected directly or indirectly to the respective motor drive unit (290).

12. The subsea system of claim 1 further comprising: the at least one connection member (200) operable to receive a signal from which a power and data signal are derivable; at least one signal processing member (225) in electrical and / or data communication with each of the connection members (200) operable to at least partly separate the power signal and data signal; and at least one motor (285) configured to actuate at least one valve (100) using the power signal; wherein the power signal is modulated responsive to the data signal.