Cashing in with TCM® retrofit
How Meridian Energy Ltd. proved that retrofitting their turbines before end-of-warranty was well worth the investment
When Meridian Energy came to Gram & Juhl in 2010 with the task of extending their TCM® feet by retrofitting 29 turbines in New Zealand, they took hold of the opportunity. Meridian Energy provides wind-generated electricity to an average of 152,000 homes a year in New Zealand. In a country where there are no government subsidies provided for wind power, New Zealand’s largest electricity provider, Meridian wanted to ensure viable renewable energy production, and therefore decided to retrofit their four year-old wind farm with TCM®
The Ultimate Decision
When Meridian’s Helen Steward was asked why they decided to retrofit their 29 turbines with Turbine Condition Monitoring, she replied, “primarily to monitor the condition of the bearings in order to detect damage early, so that we could hopefully avoid consequential damage and complete gearbox failure. Also, to enable us to plan maintenance and down-time and to order spares in time, particularly since we tend to have long lead times on parts out of Europe.” With Meridian’s desire for early failure detection and readily available parts for scheduled downtime, came their commitment for using TCM® and the commencement of the retrofit project in the fall of 2011.
IMS & HSS Bearing
After the successful installation was completed in the spring of 2012, Meridian’s own Mechanical Engineer, Helen Steward was able to catch the first signs of damage.
Cashing in with TCM® retrofit
Here is her story:
“Prior to end of warranty at one of our wind farms we decided to retrofit Gram & Juhl’s TCM® in our turbines. We installed TCM® about eight months before the end of warranty and over that time the data collected was analysed and used to prioritise where videoscope inspections should be carried out.
Increasing vibration levels were seen at five turbines, which correlated with IMS bearing damage to the inner race. The visual inspections confirmed the findings and showed the early stage of failure. As a result Gram & Juhl were able to keep the turbines running until new bearings arrived. Downtime was scheduled and the bearings were replaced in-situ under warranty. Similarly, TCM® indicated an inner race fault on three HSS bearings. Visual inspections were carried out, but due to restricted access no damage was found. We continued to run the turbines but ordered three replacement HSS bearings. When we replaced the three bearings, we visually inspected the removed inner raceways. On one inner race, two hairline cracks could be seen. The other two bearings are undergoing crack testing at present.
TCM® allowed us to identify bearing damage before it became significant enough to cause secondary damage in the gearboxes. This allowed us to order the bearings and plan turbine downtime to change out the bearings in-situ. Having such advance warning of failures is crucial in maintaining turbine availability and avoiding high replacement costs associated with complete gearbox failure.”
Let Meridian's success story be yours!
Worth The Investment
Did you know that with the purchase of a TCM® system, you will be able to pay back your initial investment and operation of the TCM® system more than four-fold during the retrofitted turbine’s lifetime? This figure does not account for savings on crane mobilization dwarf call-outs, improved purchasing of spare parts, and lower insurance premiums on your wind turbines. With TCM® you can also make cross-turbine comparisons or even cross-site comparisons, and build up a knowledgeable database of your turbine’s lifecycle.
With the TCM® system installed, you are covered...
The TCM® system covers your drivetrain, supporting structure, gearbox, generator, rotor hub, and blades, on average summing up to an increased uptime of 3.4 extra days per year. This information is based on the ISET German report, “Reliability of Wind Turbines” where failure frequency and days of downtime per wind turbine component are defined. The study was conducted over the course of 15 years on 1500 WTGs to track component failures. TCM® is able to cover half of these components. Contact our Sales Department for a presentation on TCM® Retrofit, and we will show you the math.
The Right Timing
The best time for installation is well before the end of turbine warranty, so you have a clear picture of the turbine conditions and can be ensured that there are no impending defects when you take over O&M as a utility provider.
A Typical Installation
Gram & Juhl’s TCM® system can be tailored to fit on all existing turbine types and models. Once we receive your retrofit request, we will ask you to fill out our Installation Questionnaire which provides us with imperative information about your turbine and the existing turbine infrastructure. After establishing the installation design and confirming which drivetrain components you wish to monitor (i.e. typically main bearing(s), gearbox, and generator bearings), we will then submit an offer to you based on your condition monitoring requirements.
A TCM® Retrofit installation will include:
- M-System (data acquisition unit placed in the nacelle)
- Accelerometers, structural vibration sensor(s)
- Cable harness to connect the sensors with the M-System
- TCM® Site Server software
- TCM® Ocular model (kinematic model of your turbine)
- On-site installation supervision
- Ongoing support
During the initial quoting process, a few decisions will need to be made on your behalf regarding the mounting of accelerometers as well as cable length. Accelerometers can either be adhered with epoxy or drilled and tapped directly into drivetrain components. If you have an existing vibration-based condition monitoring infrastructure in your turbine nacelle, it might be possible to use the existing accelerometers in the nacelle.
It is additionally important to make sure that cabling from the M-System to the accelerometers is of adequate length.
Upon acceptance to our retrofit offer, we will ask you to fulfill a few installation pre-requisites, which include the following:
- Procure a server
- Provide an IP plan
- Ensure network connectivity
- Install a NTP time server on the network
- Establish active power signal
- Secure appropriate power supply
- Supply RPM signal
With our guidance, you will need to secure a site server for your site with 5-10 GB of storage per turbine. We will then install the TCM® Site Server software on this server. Gram & Juhl will also need a formal IP plan, so that we can configure your M-Systems with proper network settings (i.e. fixed or DHCP assigned IP addresses). We must ensure network connectivity in the nacelle as well as an accessible NTP time server.
The final three requirements for installation can be resolved up in the tower: active power, power supply, and RPM signals. Firstly, if there is no active power signal in the nacelle, we can establish active power by clamping a CT clamp onto one of the generator’s power cables. Secondly, we must have a 24V DC power supply available for use with M-System. Finally, we will need a RPM signal measured on the high-speed shaft. This may be provided by the controller or this can be done with the mounting of a RPM sensor. We need the RPM signals to create tracked measurements. This concludes all installation preparations.
THE BOTTOM LINE: In the course of eight months, Meridian was able to save five gearboxes with TCM® Retrofit, amounting to a total cost savings of $2,690,000 USD!