A maiden voyage for Power Plant Electrical Technologies.
The Africana, a South African Marine Research Vessel (RV), was first commissioned in 1982 for the then Sea Fisheries Research Institute. The Department of Agriculture, Forestry and Fisheries (DAFF) now guides the Africana’s mandate, focusing on research to guide the management of South Africa’s offshore fisheries. The Africana has an impressive track record of achieving almost 40 000 scientific stations, hosting an array of scientific equipment on board utilised for biological physical and chemical oceanography research. The Africana is equipped with hull mounted acoustic transducers and high tech echo sounders, making her one of the best vessels globally, for hydro-acoustic surveys. An ice strengthened hull, underwater sensor deployment of up to 6000m depths, various sampling nets for demersal and pelagic trawling makes the Africana a scientific tool of privilege. She has been used by universities all over the world to conduct research to help us better understand our oceans, fish life, and the effects we are having on them.
Furthermore, the Africana provides important information for our R6 billion per annum fishing industry to help develop and sustain our ocean resources. This research specifically spans along the 3000km South African coastline linking the east and west coasts of Africa. 10 000 species of marine plants and animals have been recorded in these diverse shores. Unfortunately, the biodiversity that was one experienced on our coastline is slowly declining. The 2012 “Status of the South African Marine Resources Report” indicates that the general drop in local wild fish resources falls in line with worldwide abating trends. A recent report from the United Nations (UN) also highlights vast ecological problems in global fishing levels, estimating more than two thirds of the world’s fish resources being overfished or fully-harvested. The loss of fish habitats, rising levels of ocean pollution and climate change are reasons given for the rapid decline of the remaining fish and marine plant populations. A vessel such as the Africana is thus a pivotal instrument to help preserve our oceans and wild fish populace.
For the better part of 4 years, the Africana had been laying in Cape Town harbour, classified as a “dead ship” (meaning it is unable to propel itself and being deemed unseaworthy). Due to the unique scientific capabilities that the Africana possesses, the government set on a path to rectify the situation and return her to her oceanic duties. A replacement vessel was estimated to be valued at over R1 billion, which would have to come out of government coffers and, ultimately the tax payer’s money. As she is considered to have another decade of hull integrity to withstand ocean conditions, repairing her was the most feasible option.
The project to repair and maintain the Africana has been managed by numerous entities including Nautic and DAMEN SA, the South African Navy and the South African Maritime Safety Authority – Marine Special Projects (MSP-SAMSA). However getting the propulsion system to work proved to be a major setback. Factors such as old hardware, aged instrumentation, maintenance constraints and degraded wiring rendered the vessel in-operative.
The propulsion system of the vessel consists of a single screw, powered by three APE Allen diesel engines each developing 1044 kW at 600 rpm, three 750 kW Siemens DC generators supplying two Siemens motors of 1790 kW at 174 rpm. The electrical power on the vessel is generated by two 550 kW Siemens alternators which is driven by two of the three main diesel engines. Auxiliary power is generated by a 437KW Deutz Diesel Engine driving a 350 kW Siemens alternator.
The DC Loop for the main functions on the vessel consists of the three generators connected in series and the four DC motors, namely the two Propulsion Motors, the Bow Thruster Motor and the Trawl Winch Motor, all connected in a series loop.
These generators and motors were switched in and out of the closed loop, randomly. At least one generator was required to be switched in on loop at any time. If an additional demand of any kind was experienced, more generators were switched in on loop, as load requirements increased.
The DC Generator and motor control for the ship propulsion consists of three different systems which were installed in the year 2000. These comprised of a DCS, ABB PLC and a set of ABB excitation controllers used to regulate the excitation of the DC generators and DC motors, as described above.
As Power Plant Electrical Technologies (PPE) focuses on supplying high technology systems and solutions for the process industry, mining and utilities, this kind of marine project was the first of its kind. Working on sound engineering philosophies that engines, motors, generators and controls all work on the same principles, PPE in collaboration with African Traction Systems (ATS), applied its land based industrial experience to the challenge at hand, and undertook the Africana upgrade project.
The PPE commissioning team managed to get the closed loop system operational again and for a brief moment the propeller turned again after many years, however this excitement was short lived as a failure on the setup switches forced the vessel owners and the PPE team to re look at the whole propulsion system of the vessel.
A collective decision was taken to re-design the installed closed loop system to a parallel DC Bus system, which would allow the vessel to be operated with a totally new propulsion system. The system was designed to have operational redundancy and advanced safety features that were not present on the closed loop system.
As the control system was aged, (the typical reliable life for such systems is estimated at 10 to 12 years), little or no effective support could be sourced to get these systems operational again.
This entailed the re-engineering of the DC generator and Motor excitation equipment and controls and changing the excitation philosophy allowing an improved control and higher effective output of the machines.
- The first marine project executed by Power Plant Electrical Technologies.
- The first implementation of the new ABB PLC processor in Africa (ABB AC500 PM595).
- An expedited delivery of key PLC components. Supported by ABB SA, the PPE/ATS team managed to expedite a 7 day delivery from Europe, for key PLC components.
- Completed the custom design of the DC Bus and DC inverter controller panels for the DC Generator and Motor power distribution and regulation, in a period of 2 months.
- Achieved Lloyd’s certification and completed successful sea trials within five months of starting the project (the vessel was required to be re classed as a new propulsion system was installed).
- Since the Africana was re-commissioned in May 2016 she has been at sea conducting here duties as intended with minimal downtime.
Graham Hulley, Automation Manager at PPE, further described the project experience.
“The diesel-electric systems are unique and are to the best of my knowledge not widely in use. After retrofitting all the electrical panels, the project turned to be a complete rewrite of the logic and control on board of DC system. Human Machine Interfaces (HMI’s) were installed inside the Masters and Chief Engineer’s cabins improving the communications on board, cutting out the need to radio the engine room for updates. The HMI’s were also programmed to improve efficiency of troubleshooting, removing the need for an alarm list and thus improving the ship management and systems.”
Since the completion of the Africana project PPE have also successfully commissioned alarming systems on two off-shore patrol vessels for the Paramount Group, these vessels are on their way to Nigeria.
Power Plant Electrical Technologies sends a special thanks to:
- the Engineering team and Crew of the Africana, for positive support and commitment.
- African Traction Systems for an effective power electronic system design and commissioning support.
- ABB South Africa for expending PLC equipment, DC breaker spares and occasional emergency response support during the project.
- The PPE and ATS project team for meeting tight deadlines, sometimes under challenging circumstances.
- The owners of the Africana, for the faith and trust placed in PPE and ATS, which we believe have reaped positive rewards with a sea worthy and reliable vessel.
As new comers to the marine world, PPE relied on solid engineering principals, experience in industry and power generation and the good will and commitment of its employees to succeed with this project. We look forward to growth in the marine industry and expanding our service offering to DAFF and other marine customers.