Xayaburi HPP——Green giant on the Mekong River
Xayaburi Hydroelectric Power Plant is located on the Mekong River in Xayaburi Province, Lao PDR, approximately 80 kilometers south of Luang Prabang, and 1,900 kilometers from the Mekong River Delta. The site’s unique topography in a sparsely populated area makes it ideal for large hydropower developments. The power project has the installed generating capacity of 1,285MW for electricity production of 7,370GWh per annum. The project comprises 7 turbine generator units of 175MW each that will generate and transmit power through the 500kV transmission system to the Electricity Generating Authority of Thailand (EGAT), and one 60MW unit that will be connected to Lao state grid through the independent 115kV transmission system to supply reliable and clean energies for local residents and industries. The key project in the whole Southeast Asia, Xayaburi HPP has integrated the suggestions and expertise of many state-of-the-art international engineering consulting companies, e.g., Pöyry Energy Limited from Switzerland, AF-Consult Ltd. from Switzerland, Compagnie Nationale du Rhône (CNR) from France, the TEAM Group from Thailand with proven technologyfrom world’s renowned suppliers represented by ANDRITZ HYDRO.
The contract price of supplies is approximately US$360 million for ANDRITZ HYDRO. The scope of supply ANDRITZ HYDRO comprises the delivery of 7×175MW and 1×60MW turbines as well as generators, governors, automation systems and auxiliary equipment. Thereof, the scope of supplies for ANDRITZ China includes: manufacture and transport of large components for turbine and generator, as well as services from design, procurement to site commissioning of the auxiliary equipment of the plant, including the emergency diesel generator, grounding and lightning system, electrical power systems, elevators, communication system, auxiliary hoist, firefighting, water supply system, HVAC, portable water, life waste water treatment system and etc. The Xayaburi Project commenced officially on Oct.25, 2012. And seven years later, the power plant had been handed over to XPCL and had achieved commercial operation at the end of Oct. 2019 as scheduled.
The Xayaburi Project has created many world records. It's worth remembering that EGAT runner is the world’s largest oil-free runner with diameter of 8600mm, weight of 250 tons and power output of 175 MW. Then we have to mention the accomplishment of ANDRITZ Chengdu Assembly Shop (HCD). The HCD assembly shop is a rented area in Techcent workshop with limited area of 400㎡. Since the components of Xayaburi Project have big size, and the components of one Xayaburi turbine alone would make the available space tight, let alone other ongoing projects. At the peak storage period, the occupation rate exceeded 80%. It was a big challenge for assembly and logistics transport and required improvement in assembly efficiency as well as optimization of the space arrangement. Our HCD assembly shop was a new one and the workers were young, but everyone was energetic and eager to contribute with enthusiasm. With lessons learned from previous units and foreseeable problems settled in advance, the assembly efficiency was greatly improved and hours booked were reduced significantly compared with the previous units: Hours on U7 just accounted for 40% of that on U1. The impossible success of this series of challenges cannot be achieved without the support and cooperation of the group departments, and both Xayaburi Team and Chengdu Assembly workshop are entitled to be proud of themselves.
All projects are unique. Although the experience can offer reference to the new ones, each project is still full of new challenges. The original schedule was tight, and the civil structure changed a lot and the size of the main power houses also had great changes based on the site conditions. A new Pump house No. 2 was added and the left-bank auxiliary power house was built. As a result, the design made previously should be adjusted significantly. Moreover, the operator proposed extra acceleration requirements, which made the project time schedule impossible to be fulfilled. The cycle time for main equipment manufacture was approx. 39 months, and components were ordered from over 20 suppliers (2 main suppliers for structural welding components, 1 for main casting / forging, and others dedicated to small items) in 6 countries. It was a big challenge to cooperate with such a huge number of different suppliers to get the parts in time. There’s approximately 2 months “gap” between units in manufacturing, but it’s risky to place all units at the same supplier particularly for assembly components like distributors and runners. As an old saying goes, you can't put all your eggs in one basket. It’s important to develop different supplier strategies based on the component category and also separate unit supply alternatively to different suppliers. In this way, the project risk can be minimized and there’ll theoretically be of substitution in case there’s delay for anticipated items. To achieve the goals, an in-depth kickoff meeting with suppliers shall be held to clarify technical requirements and convey ANDRITZ specification and acceptance criteria. It’s important to ensure all parties are using the same latest revision of documents and COS platform for document exchanges. It’s also flexible to foresee and outsource works in case of bottlenecks provided pre-audit for sub-contractors. Transparency and proactivity are the basic rules to cooperate with suppliers for project monitoring. Except local supplies, it’s inevitably to have imported parts. However, this is normally the scope that progress is hard to control. The project execution team has to split the scope and start ordering at earlier stage. Clarification of characters and application area for each imported item shall be prepared in advance for Customs Clearance use. In a word, to ensure the on-time-performance is a comprehensive but also detailed task. On one hand, the project execution team need to grab an overall picture of site needs and target on the critical paths; on the other hand, series of detailed data analysis such as performance review, trend analysis, or maybe what-if scenario analysis shall be done for the baselines and milestones for each system, and countermeasures must come into force immediately. Although many challenges came out during execution of Xayaburi Project, the team members focused on analysis of problems and learned experience from mistakes to ensure accurate delivery of the components in time, offering precious experience for follow-up projects and building a skilled and responsible international young team.
Xayaburi HPP is a run-of-river power plant. The total outflow of water that goes through the power plant equals the natural inflow of water, and no water is stored or channeled away from the Mekong River. Thus, the water volume which passes through the project is fully maintained.
Xayaburi HPP has been appropriately designed using the best available technologies in hydropower development to prevent and minimize all environmental and social risks. In particular, these include fishery resources conservation, sediment routing, navigation and riverbank erosion. ANDRITZ HYDRO, with assistance of the civil company, optimized the turbine design and proposed the best fish-friendly design in the industry. In addition, it added a dedicated fish return channel and installed fish lighting devices in the fish channel, guiding the fish home by the man-made sunshine.