JUL-AUG 2019

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15:55 15:56 15:57 15:58 15:59 16:00 16:02 16:02 16:03 16:04 16:05 16:06 16:07 15:55 15:56 15:57 15:58 15:59 16:00 16:02 16:02 16:03 16:04 16:05 16:06 16:07 15:55 15:56 15:57 15:58 15:59 16:00 16:02 16:02 16:03 16:04 16:05 16:06 16:07 15:55 15:56 15:57 15:58 15:59 16:00 16:02 16:02 16:03 16:04 16:05 16:06 16:07 36 INTECH JULY/AUGUST 2019 WWW.ISA.ORG AUTOMATION IT First applications of advanced integral monitoring approach Audible noise—An early indicator of failures Audible noise is an early indicator of me- chanical problems in equipment. A typical mechanical system starts rattling or mak- ing other noises before it breaks. Hence, microphones were selected as a first inte- gral measurement quantity to develop the new type of monitoring system. Audio de tection has been installed in pilot sites for a long-term test under real conditions. Start-up sequence analysis To give an idea of what can be heard and diagnosed, the diagram shows a start-up sequence of a hydropower unit that was equipped with five mea- surement units in different locations across the hydropower unit (figure 3). Assuming the start-up sequence of the plant is fixed, the algorithm can now match any future start-up sequence and immediately issue a warning if it is not in accordance with the reference case. It is also noticeable that some of the events do not influence all signals in the same way. This is due to the spatial separation of the measure- ment locations. Thus, the col- lected informa- tion only becomes meaningful and useful for diag- nostics with the actual technical context of the installation. Interpretation of acous- tic data relies not only on machine learning but also on a large amount of domain knowledge. Potential failures to be captured The table has examples of events that were indicated by audible noise up- front (figure 4). The collection is based on experience over the years and a se- lection of recent cases. Some of the cas- es actually led to an unplanned stop of the machine with major repair work re- quired. It is interesting to note that the examples are not limited to a specific type or size of machine. In a number of cases, an early indication by acous- tic monitoring would have prevented major damage and significantly saved maintenance costs. Safety, security, and privacy for cloud-based approaches Cloud-based software, network, and computing technologies bring oppor - tunities to gain knowledge from vast amounts of data, but also bear certain risks. The safety of a hydropower plant must not be compromised. It is ensured by the following: l The integral monitoring system performs only non-mission-critical operations. l Only one-way data transfer away from the hydropower plant is enabled. l The monitoring system uses com- munication channels that are sepa- rate from standard process control. These measures make sure that the integral monitoring system does not interfere with any plant safety and pro - tection, control, or supervisory control and data acquisition (SCADA) systems. Depending on the user's requirements and trust in information technology (IT), these principles can be imple - mented either as software or hardware. Still, communication across the Inter- net is needed to establish a dataflow between the cloud computing system and the monitoring system on site. Connection of advanced monitoring systems to the cloud One critical part of information se curity is the router, which separates the mon- itoring network from other networks in the direction to the Internet. The VPN router is set up so that it cannot be con- nected from "outside." It will simply re- fuse all connection requests. Separate, dedicated communication channels are strictly built up by the monitoring system and the router themselves. They contact the cloud actively and via tun- nels, not the other way around. Being not actively reachable from "outside" is an important measure to increase security. Each OnCare.Acoustic device on the user side, for example, is equipped with a private certificate. Thus, the cloud can identify the connecting devices, as it holds their public key. Additional security is provided by the fact that cloud components also have a private certificate, so devices can verify their intended connection counterpart. Routers with integrated firewall and certificates are important cornerstones of security during data transport. How- ever, they are supported more by mea- sures, like encryption, which are stan- dard in modern communication, such as AMQP, which was first used in the banking and finance sector. Connecting advanced monitoring systems to the power plant Another critical part is the connection between the OnCare.Acoustic system and the control system or SCADA sys- tem of the user. The system provides better diagnostics if it knows about the operating conditions of the power Figure 2. Installed sound recorder. Location / event Generator Shaft Turbine manhole Auxiliaries Excitation cabinet Audible event 1 Air compressor on 2 Air compressor off 3 Oil pumps on 4 Oil supply to bearings on 5 Filling of spiral start 6 Wicket gates start opening 7 Excitation on 8 Synchronization 9 Maximal power reached 1 2 3 4 5 6 7 8 9 105 100 95 90 85 80 105 90 80 70 60 100 90 80 70 100 90 80 70 95 90 85 15:55 15:56 15:57 15:58 15:59 16:00 16:02 16:02 16:03 16:04 16:05 16:06 16:07 Sound pressure [db] Figure 3. Audible patterns during a start-up sequence.

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