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Electrical Equipment for Small Hydropower Plants Generators with Permanent Magnet Excitation (PME)

Jochen Bard Head of Energy Conversion Institute for Solar Energy Supply Technologies (ISET) Kassel University, TNSHP: Small Hydropower Workshop


Lausan June20

Institut f端r Solare Energieversorgungstechnik e.V.

Systems Technology for the Use of Renewable Energies and Efficient Energy Conversion Applications-oriented Research and Development  Wind Energy  Photovoltaics  Use of Biomass  Hydropower, Ocean Energy Technologies  Energy Conversion and Storage  Hybrid Systems  Energy Economy  Information and Training Executive Board: Prof. Dr.-Ing. J端rgen Schmid Dr. rer. nat. Oliver F端hrer Personnel: 75 Employees Budget: approxim. 8 Mio. Euro Information:

Electrical Equipment for Small Hydropower Plants • turbine: electrical drives for guide vanes and runner control • generators: high efficiency induction machines, direct drive concepts • low loss & environmental friendly transformers • improved control: ƒ improved gate control ƒ optimised trash rack cleaner operation ƒ higher turbine output (optimisation of runner –guide vane setting) ƒ detailed monitoring and supervision ƒ remote control and SCADA-interface (web cam, automated reports) ƒ advanced analysis facilities ƒ optimisation of multiple turbine installations ƒ ...

examples of improvements in particular for modernisation

Medium to high head turbines small pelton

Source: Hitzinger

spiral case Francis

Project/Country: Type: Nominal output Speed: Specification:

EW L端sen / I SGT9D06T 1400 KVA 1000 rpm IEC 34, VDE 0530

Typical low head site: SHP plant Lewitzschleuse head: 3.6 m power: 270 kW discharge: 9 m³/s Turbine: Kaplan n = 190 rpm ∅ = 1600 mm

disadvantages of gearboxes losses of 1-1.5% per stage (up to 5% overall)

vibration and noise

investment cost and lifetime

maintenance requirements and cost

environmental risk from oil


1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 0


10 power [kW]



Alternative to gearboxes: reinforced belt (up to 400 kW)

Example of submersible turbines with direct coupled induction generator ITT Flyght

hydropower plant Reichenbach/Fils

Kaplan turbine: speed and torque vs discharge (simplified with constant design parameters) 800

80 turbine speed [rpm]



torque [kNm]














0 0






discharge [m続/s] at 5 m

90 kW

700 kW

torque [kNm][kNm] number of poles, torque

turbine speed [rpm]

equivalent number of poles

Performance improvement by replacing and old drive train 1 0,9

power train efficiency

0,8 0,7 0,6 PME generator


ASG+belt 0,4

old power train (ASG+ gear box)

0,3 0,2 0,1 0 0





50 Power [%]






Possible drive train arrangement for refurbishment using a direct coupled SE or PME synchronous generator

source: OKD

Design and operational aspetcs of grid connected PME generators + no excitation losses → very good part load efficiency + smaller pole pitches than separate excitation → lighter design + no brushes or slip rings - damping of oscillations between grid and rotor required - no regulation of the power factor - voltage proportional to speed → no regulation of the voltage run away speed + loss of load → very high open circuit voltages - no isolated operation possible


stator → only for integration into an existing strong and stable electrical network e.g. in Europe and North America

New compact turbine concepts using direct coupling Matrixturbine 200-700 kW per unit

ECOBulb Kaplan turbine 500 kW-5 MW 2 to 15 m

pictures: VATECH Hydro

ECOBulb: typical efficiencies achieved




source: VATECH Hydro

ECOBulb generator first machine 330 kVA 214 rpm max. eff 96% pole face with magnets damper cage

1250 kVA, 150 rpm, max. eff 96,5% 4000 kVA 144 rpm max. eff 96,8% photos: VATECH Hydro

Straflo Matrix by VATECH

pictures: VATECH Hydro

StrafloMatrix pilot project Agonitz 700 kW at 8.5 m head 430 rpm, 1.12 m runner diameter unregulated turbine ring generator with PME target size > 1.5 MW

realised slow speed generators in µ-hydro demonstration projects refurbishment of a low head Francis turbine head 1m, discharge: 2.9 m³/s rated power 22 kVA rated speed 42 rpm

PME generator for a water wheel power 16 kW speed 22 rpm 24 poles efficiency 88% stator diameter 1,2m

rated torque 5000 Nm rated frequency 21 Hz power factor 1,0 weight 3,2 t Köhler, Karslruhe University , 1997

projects in Switzerland •engineering school Biehl •Swiss SHP programme 2003

source: Kassel University

EC-Project VASOCOMPACT: Development of a commercial concept for variable speed operation of unregulated submersible compact turbines

• new turbine design for runner and guide vane • special PME-generator directly coupled • special frequency converter • scaling from 50 bis 500 kW per unit • installation and test of a 50 kW pilot this summer (Tirva, Finnland)

Stator windings direct flow cooling

draft tube Rotor


fix runner fix guide vanes

Generator with permanent magnet excitation (Elmotec, CH)

rated speed 600 rpm, 40 poles rated frequency 200 Hz design torque 840 Nm voltage 313 V, current 92 A

Application example for the VASOCOMPACT turbines

example design

3,18 m head 12,4 m続/s discharge 324 kW power/unit

1510 mm runner 265 rpm PME-Generator

Future prospects of PME generators Innowind 1.2 MW PMG 21 rpm 96 t

similar developments e.g. by Siemens: first PM motor in 1987 other applications: • CHP units based on ICEs • industrial drive applications

ABB medium Speed Permanent Magnet Generator integrated into a one-stage gearbox 120-240 rpm some MW new high speed PMG 3.6 MW on a 500mm frame >98% efficiency