Solutions developed by Mita-Teknik are well known on the market of wind ...
2000, leveraging its considerable experience in automated control systems ...
number and periodicity of different monitoring tasks, which could also include
automatic.
REMOTE WIND TURBINE GENERATOR CONDITION MONITORING WITH WP4086 SYSTEM Victor Isko, Victor Mykhaylyshyn, Ivan Moroz, Oleksandr Ivanchenko, Peter Rasmussen Victor Isko MITA-TEKNIK, Condition Monitoring System
[email protected]; skype: mita_vls Mita-Teknik Ltd. - Kulparkivska 222a - 79071 Lviv - Ukraine + 380 032 242 04 33; www.mita-teknik.com
Abstract Solutions developed by Mita-Teknik are well known on the market of wind turbine control systems. Thousands of installations around the world produce comprehensive knowledgebase regarding behaviour of WTGs under various operating conditions. The gained experience becomes a key factor in developing efficient condition monitoring system by means of vibration analysis using WP4086 controller integrated into SCADA system. This paper gives an overview Mita-Teknik’s WP4086 CMS system. The first part of the paper introduces a general concept of condition monitoring together with features of in-depth expert signals analysis; shows its innovative aspects and complete integration into the SCADA Gateway system. The second part is dedicated to the practical application of the WP4086 monitoring system, including examples of early local faults detection.
Introduction Systems of wind turbine generators (WTGs) condition vibration monitoring are usually developed by either turbine manufacturers or companies highly experienced in vibration monitoring. Mita-Teknik started developing its own vibration condition monitoring system in 2000, leveraging its considerable experience in automated control systems for wind energy industry. The installed control systems enabled the company to gather comprehensive data regarding behaviour of WTGs under various operating conditions. Such knowledge and experience constitute a solid foundation for developing WTGs condition monitoring systems based on vibration signals. As a result, Mita-Teknik’s WP4086 MK1 and MK2 systems are certified by Allianz and today constitute integral part of SCADA Gateway within WT control system created on the basis of WP3x00 / WP4x00 controllers. One of the major concerns in investing in wind turbines and wind farms is related to the availability of the turbines, i.e. the risk of having insufficient wind power production from the wind turbines due to unpredicted stand still and repair actions. Therefore, reliability of the structures and the wind turbines is essential for the wind farm to perform successfully. Even minor failure in critical components of the wind turbine can cause unacceptable down time and losses. The operation and maintenance of wind turbines are costly. One of the practical approaches to reduction these costs is regular condition monitoring with the aim to detect failures of critical components as early as possible. As the number of installed wind turbines has increased dramatically and so have major failures of critical components the necessity of condition monitoring can not be neglected and became of a vital importance. Some components, although designed to last for the turbine lifetime, fail earlier than expected and cause unscheduled down time which harm the overall success of the wind farm project. Approaches and Methods Mita-Teknik’s WP4086 condition monitoring system (CMS) is a complete commercial solution combining hardware and software components. The major component of the system is a deep knowledge and competence in the fields of WTG’s behaviour under various operating conditions and proprietary developed and optimized WTG controllers and controlling applications. The hardware part includes industrial remotely operated WP4086 module which supports up to eight vibration measurements input channels and two auxiliary digital inputs for extension purposes, used for vibration analysis, which surveys pre-determined critical vibration levels. The number and placements of vibration sensors can vary depending on the type of WTG and drive train construction but always should cover critical WTG components such as main bearing, gearbox and generator (figure 1).
Figure 1. WP4086 CMS installation
Figure 2. Gateway system Controller application featuring advanced and flexible configuration for condition surveillance together with powerful SCADA system called Gateway form software part. Gateway enables users to control turbines behaviours under different variable conditions and retrieve various parameters of WTG operating such as wind speed, generator rpm, produced power and many others that could be used for efficient surveillance (figure 2). Such vital information together with vibration data is required to properly evaluate running conditions and take O&M decisions. Gateway features various specialized tools for operators and experts, enabling them to analyze vibration samples. However, the basic analyzing routines are automated and configured by the internal Task Scheduler. As part of condition monitoring system, the Task Scheduler defines the number and periodicity of different monitoring tasks, which could also include automatic generation of various diagnostic reports. The principal concept combines highly synchronized hardware with efficient software which can work completely autonomously (figure 3). The CMS system monitors vibration levels on key components and provides exact vibration data handled through a customized software package that can be installed as an integrated part of our wind turbine control system or as a stand-alone system. Fundamental processes that do not require human presence can last until system finds any symptoms of failures, or even small increasing of vibration - depending on the chosen sensitivity. Immediate notification of WTG operator via email, sms or direct alarm appearance in Gateway system ensures that every failure event will be processed, analyzed and appropriately handled. Evidences of every detected fault are permanently logged into the system. The benefit of fully integrated CMS solution is the possibility to reuse operational data, which include variety of production parameters and logged WTG behaviours, that helps to properly assess WTG component conditions on the basis of registered vibration patterns, enabling experts to make right conclusions and select appropriate maintenance plan.
Figure 3. Concept overview of WP4086 CMS system WP4086 CMS with integrated fault prediction algorithms for rotating energy converters is the state of the art in systems, helping to reduce operation and maintenance costs. At any time CMS enables customers to review the vibration behaviour of the drive train of a WTG. A number of suitable forms, charts and specialized functions for documentation and reporting are integrated into system, and become handy tools for operators and vibration experts. The vibration signals are being measured during the operation of the wind turbine by means of accelerometers, then recorded and subsequently analyzed on WP4086 installed on WTG. This ensures an early detection of even minor defects within the bearings and gear mesh, with following conclusions regarding their running health. The secret to success lies in the correct interpretation of the measurement results. Our system, as well as most of developed CMS technologies, is being continuously developed and adapted for using with various types of WTGs and specific environmental conditions. Recently implemented methods – such as comb filtering, whitening procedure and kurtogram analysis now became traditional tools for effective processing and analysis of vibration signals, e.g. monitoring of rotor blades, bearings, shafts, gearboxes. Practical application of WP4086 monitoring system The system has been in operation on a regular basis on WTGs of different manufacturers since 2006, when practical application of WP4086 monitoring system started. The specifics of using WP4086 on WTGs with various master controllers and possibility to retrieve data buffers containing rotation speed together with the vibration signal are demonstrated. An example of monitoring frequency-selective characteristics (FSC), related to defects of WTG drive train without installed tachometer is given. For this purpose WP4086 monitoring system features exclusive option of generator speed buffer extraction from a vibration signal. In such cases, an influence of rpm variation on smearing of spectrum lines during vibration measurement is minimized or even excluded due to applying of resampling method according to rpm-buffer, sampled synchronously with vibration (figure 4). As a result, a
precise estimation of FSC monitored on fault frequencies could be made automatically without any input from vibration expert side.
Figure 4. Illustration of resampling procedure for reducing the influence of operation conditions, e.g. variation of generator rotation speed. Based on the vast experience, we must underline the importance of correct interpretation of the measurement results which could make considerable impacts on the diagnostic decisions. Usually, typical CMS system monitors hundreds of vibration parameters and characteristics in variable operational conditions, i.e. different power ranges. Such vibration calculations are not always sensitive to the weak defects on early stages or can even mask some serious defects completely. As a matter of fact, faults that only occur under marginal conditions are not always easily detected. Therefore, the correct selection of measurements is critical for proper analysis.
Figure 5. Example selection of calculated vibration characteristic Kurtosis
An innovative approach to automated selection of measure-ments for processing and analysis together with adaptive monitoring strategy is integrated into WP4086 CMS as a data management module. Depicted example (figure 5) shows the approach in practice, presenting selection of calculated vibration characteristic Kurtosis (as degree of peakedness), for the period of 130 days in wide operation conditions of WTG. Red and white dots represent values of Kurtosis calculated on the basis of separately sampled vibration signal. An increasing behaviour of this parameter is noticeable. However, when the system selects measurements according to distinctive criteria on the basis of WTG operation conditions (measurements marked by red dots), the trend is not present any more in the vibration measurements set. This effect could be explained by vibration pattern variation under wide range of operation conditions because of different load processes on components and control strategies of WTG, and some other factors. Having applied this approach, the outcome of the analysis is not distorted by improper selection of operation conditions bounds. As an example of WP4086 CMS system and applied diagnostic approaches efficiency, figure 6 shows one of the typical defects that were revealed on an early stage. The symptoms indicating this defect are registered and documented by CMS system in advance, allowing service team to plan the maintenance beforehand and avoid serious consequences. Depicted trending of overall vibration and specific frequency selective features over time allows one to track a specific type of defect, such as gears defect in this case. Development of defect was notable during a few months. Rising of gear-mesh sidebands of intermediate stage serves for computing of reliable and robust fault growth parameters. On site inspection has confirmed the accuracy of remote diagnosis result and, consequently, the decision made.
Figure 6. Example of early detection of damage
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Figure 7. Revealed symptoms of failure development Figure 7, bottom also shows examples of trend analysis for integral characteristics called Spectrum Trending indices. These special characteristics are calculated on the basis of the whole spectra content and enable us to obtain a certain characteristic value for each vibration measurement. The advantage of such characteristics is their trendableness that enables us to use them in long-term trend analysis. The system we have used produced five different spectrum trending indices serving good indicators of spectrum changes with time. We would like to point out, that such spectrum trending indices are quite sensitive to variable operation conditions, thus they should be used in combination with precisely configured data management mentioned above. The rising levels of these indicators clearly reflect damage development in the illustrated case, which prove their effectiveness and therefore their practical benefits. The visual inspection made by service team has confirmed the presence of developed faults, predicted by the conducted analysis and revealed symptoms. Examples of an early detection of local defects on intermediate stages gears of 1 MW and 1.5 MW WTGs are shown (figure 6). In both cases, WP4086 detected clear long-term increasing trend in diagnostic parameter values since defect revela-tion. Summary Solutions developed by Mita-Teknik are well known on the market of wind turbine control systems. Thousands of installations around the world produce comprehensive knowledgebase regarding behaviour of WTGs in various operating conditions. The gained experience becomes a key factor in developing efficient condition monitoring system by means of vibration analysis using integrated into SCADA system WP4086 controller. As a provider of control software for wind turbines we are able to link CMS with a turbine controller and provide additional informational data for the condition monitoring assessment. The flexibility of WP4086 CMS system means it could be installed as a totally integrated part of
our wind turbine control system or as a stand alone system monitoring the condition of the turbine. Introduced general concept of condition monitoring with WP4086 controller and specialized software with integrated features of in-depth expert signals analysis, shows valuable and promising results for many of surveillance projects.
Practical application of the WP4086 monitoring system proved its efficiency and brought positive feedbacks from our customers. The achieved success together with crucial hands-on experience enables us to extend our solution to other applicable fields within condition monitoring. Terms Wind Turbine Control (WTC) - Total control of wind turbines in all weather conditions is vital in producing renewable energy. WP4x00 - Innovative WTC with flexible range of functionalities and highest quality and security. SCADA System - An advanced remote monitoring and control program designed to interact with controllers. Gateway - SCADA System developed by Mita-Teknik. Specially designed for utilization in monitoring centres, wind turbine manufacturers engineering departments or for specialists working with design of wind turbines. Vibration Surveillance by WP4086 - Condition Monitoring System (CMS) is developed for online diagnosis and warning/alarm handling for all rotating components and suitable for all types of wind turbines. Specification & Applied Technologies Internal Memory Storage Up to 8 External Accelerometers Real-time Vibration Analysis Measurement Task Scheduler Time Domain Characteristics
Broad Band Characteristics Vibrovelocity
Frequency Domain Characteristics
FFT Amplitude Spectra FFT Envelope Spectra Frequency Selective Characteristics
Automatic Storage of Daily Data Set and Raw Data Automatic Storage of the Wind Turbine Operation Parameters Fault detection features from Time and Frequency Domain Characteristics Advanced Warning and Alarm Log Flexible Task Scheduler for automatic Data Collection, Storage and Reporting
Goal & Solution Long-term surveillance of vibrations Predict the wear and tear of the gear box
Surveillance of all types of control systems Plan ahead the replacement of different
and generator Integrate WP4086 into our control system and other software solutions
components Save time and money on our integrated solutions Efficient predictive maintenance
