{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,17]],"date-time":"2026-01-17T18:30:16Z","timestamp":1768674616555,"version":"3.49.0"},"reference-count":35,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2018,3,30]],"date-time":"2018-03-30T00:00:00Z","timestamp":1522368000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Hydropower plants are of paramount importance for the integration of intermittent renewable energy sources in the power grid. In order to match the energy generated and consumed, Large hydraulic turbines have to work under off-design conditions, which may lead to dangerous unstable operating points involving the hydraulic, mechanical and electrical system. Under these conditions, the stability of the grid and the safety of the power plant itself can be compromised. For many Francis Turbines one of these critical points, that usually limits the maximum output power, is the full load instability. Therefore, these machines usually work far away from this unstable point, reducing the effective operating range of the unit. In order to extend the operating range of the machine, working closer to this point with a reasonable safety margin, it is of paramount importance to monitor and to control relevant parameters of the unit, which have to be obtained with an accurate sensor acquisition strategy. Within the framework of a large EU project, field tests in a large Francis Turbine located in Canada (rated power of 444 MW) have been performed. Many different sensors were used to monitor several working parameters of the unit for all its operating range. Particularly for these tests, more than 80 signals, including ten type of different sensors and several operating signals that define the operating point of the unit, were simultaneously acquired. The present study, focuses on the optimization of the acquisition strategy, which includes type, number, location, acquisition frequency of the sensors and corresponding signal analysis to detect the full load instability and to prevent the unit from reaching this point. A systematic approach to determine this strategy has been followed. It has been found that some indicators obtained with different types of sensors are linearly correlated with the oscillating power. The optimized strategy has been determined based on the correlation characteristics (linearity, sensitivity and reactivity), the simplicity of the installation and the acquisition frequency necessary. Finally, an economic and easy implementable protection system based on the resulting optimized acquisition strategy is proposed. This system, which can be used in a generic Francis turbine with a similar full load instability, permits one to extend the operating range of the unit by working close to the instability with a reasonable safety margin.<\/jats:p>","DOI":"10.3390\/s18041038","type":"journal-article","created":{"date-parts":[[2018,3,30]],"date-time":"2018-03-30T12:43:48Z","timestamp":1522413828000},"page":"1038","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Sensor-Based Optimized Control of the Full Load Instability in Large Hydraulic Turbines"],"prefix":"10.3390","volume":"18","author":[{"given":"Alexandre","family":"Presas","sequence":"first","affiliation":[{"name":"Center for Industrial Diagnostics and Fluid Dynamics (CDIF), Polytechnic University of Catalonia (UPC), Av. Diagonal, 647, ETSEIB, 08028 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7125-0734","authenticated-orcid":false,"given":"David","family":"Valentin","sequence":"additional","affiliation":[{"name":"Center for Industrial Diagnostics and Fluid Dynamics (CDIF), Polytechnic University of Catalonia (UPC), Av. Diagonal, 647, ETSEIB, 08028 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1777-1840","authenticated-orcid":false,"given":"M\u00f2nica","family":"Egusquiza","sequence":"additional","affiliation":[{"name":"Center for Industrial Diagnostics and Fluid Dynamics (CDIF), Polytechnic University of Catalonia (UPC), Av. Diagonal, 647, ETSEIB, 08028 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carme","family":"Valero","sequence":"additional","affiliation":[{"name":"Center for Industrial Diagnostics and Fluid Dynamics (CDIF), Polytechnic University of Catalonia (UPC), Av. Diagonal, 647, ETSEIB, 08028 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eduard","family":"Egusquiza","sequence":"additional","affiliation":[{"name":"Center for Industrial Diagnostics and Fluid Dynamics (CDIF), Polytechnic University of Catalonia (UPC), Av. Diagonal, 647, ETSEIB, 08028 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,3,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Valero, C., Egusquiza, M., Egusquiza, E., Presas, A., Valentin, D., and Bossio, M. (2017). Extension of Operating Range in Pump-Turbines. Influence of Head and Load. Energies, 10.","DOI":"10.3390\/en10122178"},{"key":"ref_2","first-page":"28","article-title":"Modern trends in selecting and designing Francis turbines","volume":"28","year":"1976","journal-title":"Water Power Dam Constr."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"983","DOI":"10.1016\/j.ymssp.2004.08.006","article-title":"Detection of cavitation in hydraulic turbines","volume":"20","author":"Escaler","year":"2006","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"374","DOI":"10.1016\/j.rser.2009.07.024","article-title":"Study of cavitation in hydro turbines\u2014A review","volume":"14","author":"Kumar","year":"2010","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1016\/S1001-6058(16)60638-8","article-title":"A review of cavitation in hydraulic machinery","volume":"28","author":"Luo","year":"2016","journal-title":"J. Hydrodyn. Ser. B"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.rser.2015.09.025","article-title":"A review on fatigue damage mechanism in hydro turbines","volume":"54","author":"Liu","year":"2016","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/j.engfailanal.2012.01.012","article-title":"Failure investigation of a large pump-turbine runner","volume":"23","author":"Egusquiza","year":"2012","journal-title":"Eng. Fail. Anal."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"565","DOI":"10.1016\/j.proeng.2013.12.108","article-title":"On the fatigue reliability of hydroelectric Francis runners","volume":"66","author":"Gagnon","year":"2013","journal-title":"Procedia Eng."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"464","DOI":"10.1016\/j.engfailanal.2010.09.039","article-title":"Failures due to ingested bodies in hydraulic turbines","volume":"18","author":"Egusquiza","year":"2011","journal-title":"Eng. Fail. Anal."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1016\/j.engfailanal.2017.06.048","article-title":"Failure investigation of a Pelton turbine runner","volume":"81","author":"Egusquiza","year":"2017","journal-title":"Eng. Fail. Anal."},{"key":"ref_11","first-page":"171","article-title":"Power swings in hydroelectric power plants","volume":"62","author":"Rheingans","year":"1940","journal-title":"Trans. ASME"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Valent\u00edn, D., Presas, A., Egusquiza, E., Valero, C., Egusquiza, M., and Bossio, M. (2017). Power Swing Generated in Francis Turbines by Part Load and Overload Instabilities. Energies, 10.","DOI":"10.3390\/en10122124"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"032035","DOI":"10.1088\/1755-1315\/22\/3\/032035","article-title":"Hydro-acoustic resonance behavior in presence of a precessing vortex rope: Observation of a lock-in phenomenon at part load Francis turbine operation","volume":"22","author":"Favrel","year":"2014","journal-title":"IOP Conf. Ser. Earth Environ. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Favrel, A., M\u00fcller, A., Landry, C., Gomes, J., Yamamoto, K., and Avellan, F. (2017). Dynamics of the precessing vortex rope and its interaction with the system at Francis turbines part load operating conditions. J. Phys. Conf. Ser., 813.","DOI":"10.1088\/1742-6596\/813\/1\/012023"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1007\/s00348-015-2085-5","article-title":"Study of the vortex-induced pressure excitation source in a Francis turbine draft tube by particle image velocimetry","volume":"56","author":"Favrel","year":"2015","journal-title":"Exp. Fluids"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1007\/s00348-016-2257-y","article-title":"LDV survey of cavitation and resonance effect on the precessing vortex rope dynamics in the draft tube of Francis turbines","volume":"57","author":"Favrel","year":"2016","journal-title":"Exp. Fluids"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1016\/j.jfluidstructs.2016.11.018","article-title":"Fluid\u2013structure interaction mechanisms leading to dangerous power swings in Francis turbines at full load","volume":"69","author":"Favrel","year":"2017","journal-title":"J. Fluids Struct."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"M\u00fcller, A., Favrel, A., Landry, C., Yamamoto, K., and Avellan, F. (2014). On the physical mechanisms governing self-excited pressure surge in Francis turbines. IOP Conf. Ser. Earth Environ. Sci., 22.","DOI":"10.1088\/1755-1315\/22\/3\/032034"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"012041","DOI":"10.1088\/1742-6596\/813\/1\/012041","article-title":"Condition monitoring of a prototype turbine. Description of the system and main results","volume":"813","author":"Valero","year":"2017","journal-title":"J. Phys. Conf. Ser."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1016\/j.measurement.2015.01.004","article-title":"Condition monitoring of pump-turbines. New challenges","volume":"67","author":"Egusquiza","year":"2015","journal-title":"Measurement"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.measurement.2018.01.030","article-title":"Advanced condition monitoring of Pelton turbines","volume":"119","author":"Egusquiza","year":"2018","journal-title":"Measurement"},{"key":"ref_22","unstructured":"(2017, December 12). HYdropower Plants PERformance and flexiBle Operation towards Lean Integration of New Renewable Energies. Available online: https:\/\/hyperbole.epfl.ch."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Valent\u00edn, D., Presas, A., Bossio, M., Egusquiza, M., Egusquiza, E., and Valero, C. (2018). Feasibility of Detecting Natural Frequencies of Hydraulic Turbines While in Operation, Using Strain Gauges. Sensors, 18.","DOI":"10.3390\/s18010174"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1514","DOI":"10.1007\/s00348-013-1514-6","article-title":"Draft tube discharge fluctuation during self-sustained pressure surge: Fluorescent particle image velocimetry in two-phase flow","volume":"54","author":"Dreyer","year":"2013","journal-title":"Exp. Fluids"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"012038","DOI":"10.1088\/1742-6596\/813\/1\/012038","article-title":"Detection and analysis of part load and full load instabilities in a real Francis turbine prototype","volume":"813","author":"Presas","year":"2017","journal-title":"J. Phys. Conf. Ser."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Batllo, A.P., Valentin, D., Egusquiza, M., Bossio, M., Egusquiza, E., and Valero, C. (2017). Optimized Use of Sensors to Detect Critical Full Load Instability in Large Hydraulic Turbines. Proceedings, 1.","DOI":"10.3390\/proceedings1080822"},{"key":"ref_27","unstructured":"Koutnik, J., Kr\u00fcger, K., Pochyly, F., Rudolf, P., and Haban, V. (2006, January 28\u201330). On cavitating vortex rope form stability during Francis turbine part load operation. Proceedings of the IAHR International Meeting of the Workgroup on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems, Barcelona, Spain."},{"key":"ref_28","unstructured":"Ruprecht, A., Helmrich, T., Aschenbrenner, T., and Scherer, T. (July, January 29). Simulation of vortex rope in a turbine draft tube. Proceedings of the 22nd IAHR Symposium on Hydraulic Machinery and Systems, Stockholm, Sweden."},{"key":"ref_29","unstructured":"Oppenheim, A.V. (1999). Discrete-Time Signal Processing, Pearson Education India."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1016\/j.ymssp.2015.01.013","article-title":"On the detection of natural frequencies and mode shapes of submerged rotating disk-like structures from the casing","volume":"60","author":"Presas","year":"2015","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1115\/1.2930443","article-title":"Wavelet Analysis of Vibration: Part 1\u2014Theory","volume":"116","author":"Newland","year":"1994","journal-title":"J. Vib. Acoust."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Chui, C.K. (1995). Wavelet Analysis and Its Applications, Defense Technical Information Center. DTIC Document.","DOI":"10.21236\/ADA301762"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1016\/j.ymssp.2009.06.015","article-title":"Enhancement of signal denoising and multiple fault signatures detecting in rotating machinery using dual-tree complex wavelet transform","volume":"24","author":"Wang","year":"2010","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_34","unstructured":"Newland, D.E. (2012). An Introduction to Random Vibrations, Spectral & Wavelet Analysis, Courier Dover Publications."},{"key":"ref_35","unstructured":"Ewins, D.J. (1984). Modal Testing Theory and Practice, Research Studies Press."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/4\/1038\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:59:07Z","timestamp":1760194747000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/4\/1038"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,3,30]]},"references-count":35,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2018,4]]}},"alternative-id":["s18041038"],"URL":"https:\/\/doi.org\/10.3390\/s18041038","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,3,30]]}}}