Fitness

Reliability Centered Maintenance combined with condition monitoring systems in wind energy systems

Introduction

Lately, the wind industry has grown considerably, focusing mainly on a better economic situation, growing market and the development of large wind farms and offshore. Greater availability of wind turbines is not due to good reliability or maintenance management of wind turbines, it is because of the speed and frequency of service. System status monitoring (CMS) system is better than the traditional maintenance management to increase the reliability of wind turbines. CMS monitors the performance of the turbine example parts, transformer, gearbox, generator, etc., and accurate time maintenance work is determined using the CMS. Corrective maintenance is maintenance that takes place after the problem arose and preventive maintenance is maintenance carried out before a problem occurs. Reliability Centered Maintenance (RCM) is a structured approach to finding the balance between corrective maintenance and preventive maintenance and to determine plans focusing on aspects of reliability.

Reliability Centered Maintenance (RCM) has not yet been implemented as a tool in energy Wind in Sweden or Denmark. United States is the world's largest producer of wind energy. But it is a feasible solution for the industry wind energy. In Norway, an RCM was carried out by Vestas. And German Nordex has already directed maintenance reliability within their CMS systems. The application of the RCM is a maintenance program provided effective combined with a workable plan for equipment monitoring system for wind energy. This study focuses on monitoring the state as vibration analysis and analysis oil for industrial wind energy, extensive knowledge of the wind, the CMS could be applied to maintenance Reliability Centered (RCM) and how it was done earlier in hydropower, for example.  

Few words are needed to understand the maintenance and RCM as a possible tool for wind power. They are:

Failure rate: failure rate is inversely proportional to Mean Time Between Failure (MTBF).

Reliability: The ability of an element to perform a task under given conditions for a given time interval.   

Types of maintenance

There are two types of maintenance. They are the corrective and preventive maintenance.

1) Corrective Maintenance: This is done after the component fails. No maintenance process takes place before failure of the component. The component that failed can be repaired or replaced. It can be replaced by the component of new technologies or the same one that was available before the break.

2) Interview Preventive: This is a proactive maintenance done before the system fails. It reduces the likelihood of component failure. This is a scheduled maintenance and periodic and regular basis to avoid the appearance of failure.

a. Scheduled maintenance: preventive maintenance in accordance with a schedule established or recognized units use.

b. Condition based maintenance: preventive maintenance based on performance and / or supervision parameters. The need for maintenance is provided with statistical methods, it is when, how and why the component failed.

Optimization Maintenance

Minimize cost or maximize the resources of the interview is the main objective of maintenance optimization. The interview should be conducted so that the tools have high safety and equipment have a long life and its quality is preserved. It is difficult to find the relationship between corrective and preventive maintenance and identify corrective maintenance costs associated with given amount of preventive maintenance.

Aeolian

Wind power generation is increasingly frequent and wind turbines and farms are increasing, then there must be new ways to minimize downtime and maximize availability and profit. To transform the kinetic energy of wind power electricity wind machines are used. Parts are the main bearings, gearbox, generator, brakes, control system, a party that balances power and rotor and hub, the rotor design and the hub can vary, but most common is the horizontal axis. With two or three blades, the rotation axis running parallel to the ground. Gearbox is to accelerate the rotation from a low speed, the speed of the constant demand of the generator and it can be cooled in two days with air or water. Wind has two brakes: A brake rotor and another for emergency purposes. Control system is to maximize energy production, the car is an element that controls the different parts of the turbine and a small motor that turns a gear so that the car is always in the direction of the wind.

Two frequencies of vibration in the wind turbines are the frequency and frequency undercarriage in Typical mechanisms, there are two frequencies of speed and there are several areas that are supported by bearings which produce four different frequencies. The technique is grown old in the business of wind energy and life insurance are complaining about large and introduce restrictions to maintain. Monitoring is a way to avoid damage. Wind farm monitoring which periodically inspects the entire mechanism is the monitoring procedure common for wind energy today. Although damage can then be discovered, these inspections do not provide answers to when and how the damage occurred.

New ways of monitoring

Condition monitoring is implemented, so generalized to avoid preventive replacement. Condition Monitoring is regular monitoring of each state. It is the use of advanced technology for monitoring a machine condition and predicting failures in each state. In practice, there are two ways monitoring of the state, it is continuously monitored and another one is periodic mechanical diagnosis. In continuous monitoring, appropriate sensors are connected with the control system that triggers an alarm when the data changes, such as failures of transmission can be found at early stage by comparing the current frequency of the gearbox with the original frequency. In diagnosing mechanical periodic inspections machines are made periodically and measuring tools from the last measurement.

The cost of maintenance of a wind turbine is economically vigorous monitoring of status must be presented to the discovery of early failures to reduce costs for maintenance Corrective and repairs could be better planned and it would shorter downtime. Some of the functions of control systems in wind turbines, to approach the concept of condition monitoring. For large wind adjustment system is a system module security and is one of the most sensitive systems in a wind turbine. One cost-effective methods of monitoring the status is the inspection visual machinery, but it is limited to stationary equipment.

Two techniques for monitoring the condition explained in this study are

1. Vibration analysis and

2. Oil analysis.

1. Vibration analysis

Vibration analysis is the dominant technique used for condition monitoring, particularly for rotating equipment, while the wheels of turbines turbines and bearings in the gearbox, the bearings in the generator, main bearing can be adequately monitored. Analysis vibrations is not new. In the early 80s, the instrumentation and skills required for systematic monitoring of noise or vibration condition based have been completely developed.

Having the state power of the wind is indicated by the noise than rotation per minute (rpm) and more stress bearing wear quickly. A few years ago computer equipment to measure and assess noise the bearing condition was available, it does not need someone to go out to the wind and climb the tower to hear the bearings.

There were no products on the market for monitoring levels that have been adapted for wind turbines in early 2000. But more later, nine vibration sensors were assembled to monitor the bearings on the main axes, gearbox and generator on the turbine Elida Risholmen in the archipelago of Gothenburg. This system is called the SKF WindCon CMS.

This analysis is based on two factors, they are;

• All failure modes common components have distinctive vibration frequency that can be identified and isolated and
• The amplitude of the frequency remains constant, unless there is a change in the dynamics of machine operation.

Vibration and noise is normal in machines, it is important to remember that:

• Each machine will have a normal level of vibration and noise.
• malfunction is usually the result of increased noise and vibration.
• Own unique vibration and noise is generated by each problem operation.

The benefits, if the problem can be detected and analyzed at the beginning are as follows:

• time appropriate for curbing repair systems may be provided.
• Major damage is minimized.
• The schedule of work, manpower requirements, tools and spare parts can be fitted before stopping.
• Breakdowns Reduce machine.

Periodic monitoring is not suitable for high performance machines. For these machines, online, continuous monitoring Automatic is required using vibration sensors located at critical points on the machine where the vibration levels exceed pre-defined an alarm or the machine would shut involuntarily.

Techniques used in the analysis of machine vibration condition monitoring

Here are some techniques for monitoring packaging machine

1. curve analysis

2. Indexes

3. average synchronous

4. Orbit

5. Statistical analysis

6. fast digital Fourier analysis.

curve analysis traces the history of time events on a storage oscilloscope or a real time analyzer and wind energy. It is easy identify damage in gears and bearings, such as broken teeth and cracks.

Indices used to quantify the signals time with the help of Peak and RMS (Root Mean Square) level is not reliable in detecting damage in systems operating continuously.

Synchronous average is useful in the diagnosis of vibration speeds for multiple trees are present, not only to eliminate noise, but recurring events not synchronous with the machine being monitored. Bearing wear, shaft misalignment, unlike the tree, instabilities of hydrodynamic lubrication of bearings and rub tree are indicated by Orbit.

Statistical analysis of vibration signals drift curves machines that can be used in monitoring the state machinery. Fast Fourier analysis makes the Digital signal in the frequency domain and the spectrum of signature obtained can not afford important information regarding the status of machines.

2. Oil Analysis

Oil failure in wind energy is not always detected and it is too late when it is detected. The continuous measurement is necessary to find faults in oil. Oil analysis is used to determine the status and condition of lubricants commonly used in the turbines and equipment. The dynamic design and operation of the bearings, lubrication and the structure supporting the rotor of the machine is commonly tripology called. Analysis of lubricating oil is one of tribology technique used in condition monitoring, evaluating the state oil lubrication in mechanical and electrical equipment. Comparison of trace metals in oil samples indicates the reason for oil wetted parts that provide an indication of the likelihood of machine failure. systems based on microprocessors are available for analysis lubricating oil.

The analysis examines the oil and oil shows the elemental chemical composition of this debris. The main elements present in samples of oil are the penetration of foreign bodies such as dust and lubricant additives with shareholders.

Atomic absorption analysis infrared spectroscopy, atomic emission, plasma, X-ray fluorescence and energy dispersive X-ray analysis are examples of oil analysis techniques. atomic absorption analysis for the analysis of wear debris analysis infrared spectrometer detects and measures the atomic and molecular compounds emission is used for the analysis of debris. coupled plasma and fluorescence X-rays are used to analyze the wear debris and the elements of additive oil and energy dispersive analysis X-ray is used for analysis of dry wear debris.

Gearbox

boxes Speed monitoring is a very difficult process, because they include many interior components. Wind turbines have three transmissions that occurred several bearings and gears, it is difficult to find the source of failure. Gearbox is monitored by sensors and four or six accelerometers. Since he works in a changing environment, injuries can not be detected until the future. gearbox wear and failure is due to the load bearing elements such as shafts, gears and bearings. surface cracking of these parts are due to contact between metals in the cyclic loading and which ultimately leads to failure.

Vibration analysis investigating the vibration box speed and is divided into two categories: spectral analysis and functionality. Spectral analysis includes Fast Fourier Transform (FFT) which plots the amplitude of the vibration signal as a function of frequency.

Reliability Centered Maintenance (RCM)

Reliability Centered Maintenance (RCM) is a structured approach to finding the balance between corrective maintenance and preventive maintenance and to determine plans focusing on aspects of reliability. It determines the maintenance plan for example, priority on the critical elements and the choice of tasks Maintenance and chooses the appropriate preventive maintenance activities for the right component at the right time to reach the most qualified. The aviation industry Preparedness is the place of origin for reliability centered maintenance (RCM) and the description were the first in 1978 by Nowlan and the introduction of nuclear power came in 1980 and hydroelectric power in 1990. RCM is characterized by:

1. maintaining system function.

2. Failure mode identification

3. Function Priority

4. Choose the extent of effective maintenance

The description of process to define a plan RCM are

1. Seven Steps of 1993 smith

2. Steps to a foreground RCM – Nowlan

3. September issue of Moubray.

Seven Steps to Smith

analytical models and theoretical analysis of the tree decision is the basis of the method Smith. The seven steps are the blacksmith,

1. Information collection and the choice of system

2. Limits system which

3. System description and functional block diagram

4. System functions and loss of function

5. Failure Effect and function analysis (FMEA)

6. Decision tree analysis

7. Maintenance estimation of measurement.

Failure Effect and function analysis

In reliability analysis, the effect of failure function analysis and FMEA is used and can determine the link between the possible failure modes for construction and failure effects. aircraft manufacturer Boeing has introduced this method in 1957. To find all the means by which a product can fail is the purpose of this method. The three responses to questions are,

1. What failures / events could occur?

2. What are the effects of failures / events?

3. What causes of failures / events?

With the responses of these three questions frequency of failure is indicated by a number between 1 and 10 for example. These figures indicate the seriousness of the consequence and the probability of discovery. These figures are multiplied in a number combined index, for which a higher value indicates a worse failure and it is called the risk priority number. Estimate the size of the priority number of risks, severity of failures can be determined, then a measurement can be made.

Steps to an MRC first map – Nowlan

1. Identify areas that require intensive study by partitioning the equipment in categories of objects.

2. Identify the significant elements that affect the essential safety or economic.

3. Identify hidden features that require scheduled maintenance.

4. By selecting only the tasks that will satisfy the maintenance requirements by assessing maintenance requirement for each major and hidden functions in terms of failure consequences.

5. Identify items for which no applicable or effective task can be found.

6. Included for each task, select conservative initial intervals and group the tasks maintenance packages for the application

7. To provide factual information necessary to review the initial decisions on a program Exploration of age.

September issue of RCM II Moubray

Identify elements of the system must be analyzed is the first step to analyze the maintenance of a system. After that, according to Moubray we should respond to seven questions,

1. What are the functions and performance required?

2. How each function can fail?

3. What causes each functional failure?

4. What are the effects of each failure?

5. What are the consequences of each failure?

6. How anyone can not be prevented?

7. What if no activity is prevention possible?

The functions are what the asset is expected to perform and when the function is specified, it is important to indicate a certain level that the unit should meet. There are two functions, primary and secondary main function is the main purpose of the function of the active and secondary is additional functionality of the asset must respond. The cause of failure is then described and the consequences of failure are divided into three categories,

1. Security and environmental consequences

2. operational consequences

3. Non-operational consequences

If failure cause an environmental law being broken, it is classified as safety and environmental consequences. The environmental consequences and operational consequences have an effect on costs of production and operating and non-operational implications does that costs in the form of operations. The decision tree determines that the interview should be conducted according to the consequence of failure.

Benefits of RCM   

1. The amount of preventive maintenance can be reduced or replaced by corrective maintenance through careful analysis of failures

2. Reduced spare car parts

3. At one stage Early construction methods have proved wrong.

Reliability centered asset management (CAMR)

This method is developed from MRC principle of trying to link preventive maintenance for the total cost of maintenance and system reliability. To see the effect on a component level of preventive maintenance on system reliability, with quantitative methods, is The purpose of this technique. In this method, the critical elements identified for the reliability of the system are studied and the relationship between reliability and maintenance has been established by comparing the effect of preventive maintenance for the causes of failures for the current game score. Main stages of the approach are RACM,

1. analysis of system reliability

2. modeling the reliability of components

3. System reliability and cost / benefit analysis.

Vattenfall Vattenkraft MRC (VVK RCM) of hydropower

Vattenfall Vattenkraft developed and implemented a model of the MRC for its hydroelectric plant, it is similar to the MRC Moubray II in many aspects. This model follows the same steps in the RCM II Moubray but differs in the maintenance strategy.

1. Define the functions

2. Determine the failure of the function

3. Determine failure modes

4. Performance Risk Analysis

5. Determine maintenance tasks can

6. Analyze and determine maintenance strategies

Each function in the standard analysis is studied and functional failures are added or removed if necessary. Using the standard analysis that the failure mode reference all causes reasonable for each functional failure are listed.

Eight categories have different consequences for each failure are

1. The costs incurred due to break

2. Overall costs

3. Environment in which the work is done

4. flow dam

5. The damage occurs in the environment

6. Personal needs

7. Production stoppage

8. Efficiency

Risk analysis is performed for each failure mode and failure frequency is approximately estimated. Using the risk matrix, we can get a number between 0 and 5, which describes the risk of failure if the number is three or more than three, preventive maintenance can be used, if corrective maintenance should be used.

Data such as personnel costs for maintenance, stop time and costs due to lost production, cost of new parts for equipment damage and other costs related tasks maintenance and breakdowns are economically necessary to determine the type of maintenance that should be used.

The main difference between VVK RCM and RCM II is, VVK RCM II with the help of an analysis of risks and costs of the best maintenance strategy is taken, but the RCM II a decision tree where maintenance strategies of certain preferred and, if possible, they are selected.

Conclusion

  Planning meeting with the MRC as a system that collects data necessary to wind industry.RCM combined with CMS allows the wind industry monitoring equipment that can not be monitored continuously manually. For the entire industry, not only maintaining but reliability is also an important factor. MRC offers a better system of maintenance management increasing the reliability of wind turbines. MRC provides the amount of preventive maintenance, which can often be reduced or replaced by a corrective maintenance conservative analysis of failures. Cooperation between operators of wind farms, the owners and original equipment manufacturers (OEM) is very important to design the maintenance process based on maintenance experience in wind power industry.

 

 

 

 

 

About the Author

Malarvizhi.G, is engineering bachelor in electronics and communication and masters in business administration. She has done projects in electronics and marketing in her under graduate and post graduate programmes. She is interested in marketing research. She can be contacted at – gmalar85@gmail.com

Object Manager Video 16: Client Monitor Analyzer

HM Digital TDS-EZ Water Test Meter $24.99 Ideal for all basic water testing applications. The best value meter in the world! .. Economy model that is ideal for end-users. .. Highly efficient and accurate due to its advanced microprocessor technology. .. Hold Function: saves measurements for convenient reading and recording. .. Auto-off function: the meter shuts off automatically after 10 minutes of non-use to conserve batteries. .. Meas…

Digital PH Meter Tester for Aquarium, Fishing Industry, Swimming Pool, School Laboratory, Food and Beverage $7.11 This digital pen style pH meter is an ideal instrument for aquarium, fishing industry, swimming pool, school laboratory, beverage etc.Features: Weight: 65gSize: 15 x 3 x 1.5 cmMeter with protective plastic case and calibration screwdriverExcellent meter, very accurate and durableMeasuring pH Range: 0.0 – 14.0 pH Resolution: 0.1 pHAccuracy: ±0.1 pH (20°C), ±0.2 pHOperating Temperature: 0 – 50°C…

Large Display Waterproof Ph Meter – Pen Style By Sper Scientific $36.75 Highly stable and accurate readings with large LCD display. Designed for simple one-hand operation. Automatically calibrates to pH 4, 7, 10 buffers and can be adjusted to recognize non-standard buffers as well. Features hold function, and auto power off with low battery indicator. The case is IP65 water proof, and will float if accidentally dropped into the water. Comes with 4 button-cell batterie…

iConserve Home Energy Saving Monitor $109.99 Ever wonder how much energy that A/C unit or furnace is gobbling up each and every minute of every day? In today’s globally conscious world, keeping track of your energy consumption is no longer a novel idea, but a necessity. You may be one of the very few that actually turns off the lights when you leave the room, but where else can you cut down on energy costs and decrease your carbon footprint?…

Luster Leaf 1820 Rapitest Soil Moisture Meter $7.45 Instamatic Moisture Meter Essential for Successful Growing This Rapitest Moisture meter is an invaluable aid in maintaining correct moisture levels. This accurate instrument will help you eliminate detrimental over or under watering! An instant reading is obtained from the tip of the probe into the root level. This Rapitest is made by Luster Leaf Inc. Ships Quickly…

Luster Leaf 1840 Rapitest Soil pH Meter $15.00 Rapitest Soil pH Meter First Step to Successful Growing Have you tested the ph level of your soil lately? This award winning meter provides instant pH readings. It is important to understand the fertility of your garden soil. Inappropriate levels can result in reduction of plant growth and even prevent seed germination. This simple test can diagnose a problem and prescribe the proper medication fo…

Black & Decker PCS10 PlantSmart Digital Plant Care Sensor $19.99 Includes PlantSmart Digital Plant Care Sensor – PCS10, USB Cable, (1) AAA Battery, Storage Bag, Quick Start Card…

Practical Packet Analysis: Using Wireshark to Solve Real-World Network Problems $39.95 It’s easy enough to install Wireshark and begin capturing packets off the wire–or from the air. But how do you interpret those packets once you’ve captured them? And how can those packets help you to better understand what’s going on under the hood of your network? Practical Packet Analysis shows how to use Wireshark to capture and then analyze packets as you take an indepth look at real-world pa…

12211 03 Analyzers and Monitors Tg …

SPIRENT LAUNCHES FIRST 10 GIGABIT ETHERNET PRODUCT.(Product Announcement): An article from: LAN Product News $5.95 This digital document is an article from LAN Product News, published by Worldwide Videotex on March 1, 2001. The length of the article is 441 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.Citation DetailsTitle: SPIRENT…