Robotic Propulsion TechnologyJonathan Greening

Chief Engineer SMD Remote & Autonomous Systems

Subsea UK Underwater Robotics Conference 2020

Next Generation ROV Technology from SMD

Objectives:

• Lower OPEX cost

• Improved Reliability

• Higher Performance

• Easier of Use

• Flexibility

Why Electric Propulsion?

• Efficient - Significantly more efficient than hydraulic

• Reliable - Fewer moving parts; less leak paths

• Cheap to Operate - Lower fuel consumption and no start up in-rush (so smaller gen sets)

• Controllable - Better control over speed & torque

Delivering the Power – DC Transmission

• Reliable - AC-DC Surface System• Efficient - no reactive losses• Flexible - shared infrastructure - HV DC bus• Lightweight – smaller umbilical's

Developed with our parent company

CRRC Times Electric

Industry First – Subsea DC/DC ConverterStepping the DC HV transmission down to the vehicle bus voltage was one of the most difficult tasks.

• Power electronics - no large and heavy transformers

• Compact and lightweight - works in oil under pressure

• Reliable - quick change modular units give redundancy

• Flexible - DC vehicle bus at 680V allows• Umbilical connection • Battery connection• Hybrid Umbilical/Battery connection

Maximising Power into the Water

All-in-one modular thruster:• Built-in drive control unit• Built-in compensation

High thrust:• Class leading bollard pull• Power across the vehicle

speed spectrum

Reliable:• Magnetically coupled gearbox• No meshing gears• No shaft seal, typically

the weakest point of any thruster

• Optimised motor efficiency

Vehicle PerformanceA compact power system gives our Electric Quantum a 20% smaller footprint than existing ROVs

Higher power from smaller thrusters delivers un-rivalled power into the water:

• 1250kgf horizontal bollard pull• 1500kgf vertical bollard pull

The result is, Electric Quantum will work in higher currents than any other work class ROV, travelling at speeds up to:

• 4.5 knots forwards• 3.5 knots laterally

AND carry out heavy lift duties up to 1.5 tonnes

A look at Efficiency Electric Quantum vs Hydraulic ROV - 150kW (200hp)

If power into the water is pegged to hydraulic ROV for comparison…

The power required at the surface is:• Hydraulic – 254kW• Electric - 158kW

The overall efficiencies are:• Hydraulic – 40%• Electric – 64%

The fuel use to generate the electricity for EROV is 38% less

In addition, the generator set on a hydraulic ROV is sized to cope with in-rush current of an induction motor – typically needing a 800kVA gen set. The Electric Quantum will work with only 400kVA

Extra performance - the electric Quantum has more power available. Up to 143kW at the propellers!

Testing, Testing, TestingReliability - A priority for every operator.

Multi-Level:• Component:

• Performance• Load• Environmental

• Sub-System:• Power System• Control System• Safety System

• Vehicle:• Control Tuning• Performance

Testing programme:• Performance mapping• Endurance testing• Life - fatigue testing

Advanced Flight System

Cascade control, simultaneous rate and

position

Power Management

3rd Party interface

Dynamic PID

Online calibration for controller parameters

Control based on scenarios

Precise control in high currents

Switchable modes of operation

Avoid saturation,

Move power to where needed

Take Commands from other sources

Auto-tune

Advanced Flight Control Improved response, robust

What does this mean for clients?

Higher performance – Increase the up time of a wind turbine installation vessel by 38%

More Efficient – Kinder to environment and save $200k / year on fuel costs

High Reliability – required for Over Horizon and Un-crewed Surface Vessels operations

Advanced flight System - improves stability, quality of data and quality of operation

Questions?