Future-proofing New Zealand's hydro resources

2011-04-12 - When Genesis Energy needed to replace the control system of a hydro electric power network covering five power stations in remote locations around New Zealand's North Island, ABB delivered an advanced 800xA control system including multisystem integration to take this crucial electricity generator into the future.

Genesis Energy owns and operates 1,996 MW of electricity generation. They are New Zealand’s largest energy retailer, supplying 19 percent of the nation’s electricity. A key part of their overall generation capacity is supplied by their renewable energy group consisting of Tongariro and Waikaremoana hydro electric power schemes. These two schemes consist a total of five power stations – two in the Tongariro scheme and three in the Waikaremoana scheme – with a total capacity of just over 500 MW.

An aging system
The turbines in Genesis Energy's two hydro schemes are controlled, and monitored, from a central location at the Tokaanu Power Station. The existing control system had been installed in the early 1990s, and had reached the end of its operational life. Replacement of obsolete parts had become increasingly difficult.

The two power schemes had evolved over a number of years, resulting in a number of different technology platforms. A replacement and upgrade of the control system would provide an opportunity for Genesis Energy to rationalise the controls for each of these platforms, and allow for the system to integrate control of new power stations in the future.

Challenging locations and conditions
To add to the challenges that this upgrade presented, the upgrade work and system implementation would have to carried out over a wide geographical area. The Tongariro and Waikaremoana schemes are situated approximately 330 km apart. Within each scheme, the power plants are positioned in isolated and sometimes difficult locations.

In the Tongariro scheme, the Tokaanu Power Station, with its four 60 MW turbines, is located on the slopes of Mount Tihia, near Turangi, in the central North Island. The Rangipo Power Station, with two 60 MW turbines, is situated underground in the Kaimanawa Forest Park. Meanwhile, the Waikaremoana scheme is located between one of New Zealand's most inaccessible areas, Te Urewera National Park, and Wairoa. The three stations in this scheme, the Tuai Power Station (three 20 MW turbines), the Kaitawa Power Station (two 21 MW turbines) and the Piripaua Station (two 22 MW turbines), are located along the Waikaretaheke River.

All the challenges of this project would need to be met, and the work completed, within strict operational windows. It was vital that the project be delivered on-time, with minimal disruption to generation capacity and within resource consent constraints.

The central hydro control room at Tokaanu

ABB inspecting the control system situated in Tokaanu's generator hall

ABB solutions
ABB are committed to the concept of ‘evolution without obsolescence' – meaning that future-proofing is a top priority in ABB-designed systems. ABB proposed a control system for Genesis Energy's hydro electric plants that would allow for the future addition of extra features such as maintenance management systems, video integration, and remote business access; not to mention the expansion of the overall system for the addition of new power stations.

Taking on the challenge
In 2008, ABB embarked on the three-year project. ABB were responsible for system design, electrical design, panel build, installation and commissioning.

The system comprised of a complete offering of ABB products: an 800xA control system (extended automation) with AC800M programmable logic controllers (PLC) and S800 input / output modules (I/O), multisystem integration (MSI), and an extended operator workplace control room desk (EOW). Other elements in the system included: Synchrotact 5 synchronisers, MCM800 vibration monitoring, UMC22 smart motor controllers, and variable speed drives. All motor control centres (MCC) where implemented on a Profibus communication network.

Prior to the commencement of the project, Genesis Energy were invited to visit the ABB research centre in Västerås, Sweden, to see ABB's feeder factory and the facilities there. Genesis brought with them a very low bandwidth modem that they were planning to utilise in the control system upgrade. The technicians at the research centre tested the modem with the 800xA system, achieving perfect results. During the visit, the client also saw the ergonomically-designed EOW control console for the first time.

Ground-breaking implementation
The Genesis Energy upgrade is the first time an ABB EOW desk has been used in the South Asia region. The project was also one of the first in the world to utilise ABB multisystem integration with low bandwidth connections between remote sites.

The ABB-designed control system provides a number of new benefits. At the Tokaanu control room, information from the entire system is now available from a single interface. This interface displays real-time data from motor controllers, protection relays, vibration monitors and third-party devices such as power meters and governors across the network. The operator can easily retrieve and access secure historical plant data. The system also has integrated automatic generation control (AGC) allowing for automatic control dispatches from Transpower, the operator of New Zealand's national power grid.

Meanwhile, standardisation across all the power stations in the Tongariro and Waikaremoana schemes allows efficient maintenance and inventory management, and a reduction in the training needed for a technician to understand the overall system.

The monitoring control room at Rangipo station can be controlled remotely at Tokaanu

ABB's range of equipment in the control panel at Rangipo

Delivering on the project
The hydro power stations in the Genesis Energy network are located in ecologically sensitive areas, and resource consent compliance was taken seriously by all involved in the upgrade. ABB were able to fulfill the conditions of the consent process.

Throughout the project, ABB were required to meet an aggressive schedule and budget. Work had to be completed within scheduled fixed window outages, and as the project progressed, additional projects were rolled out within the fixed timeframe of each outage. Despite the challenges this imposed, ABB completed all outages successfully within their allocated times.

Vetti Bala, Genesis Energy's project manager for the upgrade, had a hands-on role working alongside ABB. “From the outset, Genesis Energy worked hard to develop and foster a good working relationship with ABB. We were aware the upgrade of our hydro control systems would span a number of years and that the investment would be considerable,” says Bala.

“The hydro control systems upgrade provided a huge challenge for the project team from both a technical and geographical point of view. Genesis Energy designed and implemented the complex LAN and WAN infrastructure as the platform for the new control system. The challenges included constraints from resource consenting around water flow and flooding which required close monitoring. We were fortunate to have a dedicated project team from Genesis Energy with the help of the AECOM consultants who worked closely with ABB to ensure that all challenges were worked through in an effective way.”

With total management of the system concept, electrical design, implementation, installation and commissioning, ABB carried complete responsibility for the project's success. Multiple subcontractors were coordinated on site, with over 85,000 estimated hours utilised over a two-year installation period, without lost time for injury.

“ABB had a great team of dedicated workers and subcontractors, and we all gelled and worked well together,” says Vetti Bala. “The project site implementation staff from ABB on the ground had a great attitude working in with Genesis Energy, solving issues when and where they arose during the installation period. We were also fortunate that both Transfield Services Ltd (who was the installation subcontractor for the control system) and Electrix (who installed and commissioned the generator electrical protection scheme) worked in harmony with ABB to ensure the project deliverables were met on schedule. It is a true testimony to the entire project team that the amount of hours clocked up during the installation and commissioning phase had no health and safety related incidents.”

Into the future
The new control system is already proving its worth and the careful future-proofing and ease of expansion that ABB designed into the new technology, is being put to good use. Electricity generator, Meridian Energy, are transferring their Tekapo A and Tekapo B South lsland power stations to Genesis Energy's control. A project is now underway to integrate control and monitoring of these stations into the Tokaanu control room some 1000kms away – proving that ABB's system is not only equipped to handle multisystem integration between two schemes within an island, but between islands as well.

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