Standardized Hydraulic Power Units for Small Hydro

RE 08129, Edition: 2015-07, Bosch Rexroth AG

Standardized Hydraulic Power Units for Small Hydro Applications

Contents

General Information 2Requirements and Structure 2 - 3Kaplan Turbine Application 4Francis Turbine Application 5Pelton Turbine Application 6Additional Functions for all Turbine Types 7Differential Cylinder for Turbine Regulation 8Dimension Power Unit 8 Check List for Compact Turbine Control System 9 - 12

RE 08129Edition: 2015-07Replaces: 2014-07Technical Information

2/12 Technical Information | Standardized Hydraulic Power Units for Small Hydro Applications

Bosch Rexroth AG, RE 08129, Edition: 2015-07

Civil Engineering for Energy: Weirs, Dams and Turbines

General Information

Hydroelectric power stations are the most important source of renewable energy worldwide. Individual power stations, such as the Guri Dam, the Three Gorges Dam or Belo Monte Dam, produce an overall output of up to sev-eral thousand megawatts. There is however a much higher proportion of small-scale hydroelectric power plants than large scale ones. For example, of the present 7,500 exist-ing hydro¬electric power plants in Germany, the majority have an output of less than 100 kilowatts (source: “Federal Association for German Hydroelectric Power Stations”). These small-scale hydroelectric power stations also need effective, affordable and secure turbine regulation. As a result of this, Bosch Rexroth has developed a new series of standard units (up to 10 MW turbines) for regulation of small-scale hydroelectric power; these are characterized by the following criteria, among other things:

▶ Minimum installation and maintenance work ▶ Possibility of using environmentally friendly hydraulic

fluids in accordance with the German Water Resources Act (WHG)

▶ Diverse applications enabled for each turbine type due to modular design

▶ Fast delivery due to standardization ▶ Short commissioning times ▶ Functional reliability in extreme ambient conditions

and compact design ▶ Spare parts are available at short notice due to stan-

dardized assemblies ▶ Low risk of leaks due to control block technology and

minimal pipe work ▶ Comprehensive circuit diagram can already be drawn

up during enquiry stage ▶ Cost-effective as technical planning is reduced

Requirements and Structure

The requirements of high forces, robustness, reliability and short control times mean that only hydraulic systems can be considered for turbine regulation applications. Hydraulic solutions for these applications present many challenges. The following features are particularly impor-tant for the unit:

▶ Compact design ▶ Guaranteed security ▶ Energy-efficient turbine regulation

Thanks to a modular, standardized design, the unit is divided up into the following subassemblies, which can be arranged according to the required application:

▶ Basic system with pressure limitation, filter and emer-gency shut-off device

▶ Main mounting block for regulation – The guide vanes in Kaplan or Francis machines – The angle control of nozzles in Pelton machines

▶ Connecting plates (up to 8 consumer possible) – For runner blades regulation (Kaplan) – For needle control of nozzles (Pelton) – For generator brakes (all turbine types) – For inlet valve control system (all turbine types)

Standardized Hydraulic Power Units for Small Hydro Applications | Technical Information 3/12


Requirements and Structure

The basic system contains:

▶ Tank ▶ Oil drip tray ▶ Motor-pump assembly ▶ Attached accumulator unit ▶ Pressure switch and pressure cell ▶ Pressure gauge ▶ Air filter ▶ Temperature sensor ▶ Hand pump ▶ Terminal box ▶ Voss Form screw fittings and pipe work

The basic control block contains:

▶ Electrical or mechanical emergency shut-off device ▶ Pressure reducing and relief valve ▶ Pressure filter (10 µm mesh) ▶ Mounting possibility for heating unit ▶ Accumulator safety valve ▶ Valves for setting velocity ▶ Mounting possibility for connecting plates

The assemblies included in the basic system and basic control block are independent of the application and area of the small hydro application of the unit. The basic system and the control block form the basic frame of each unit. The components can be made of different materials and sizes depending on the customer request, however they must be contained in the system.



Kaplan Turbine Application

Kaplan turbines are suited to low, fluctuating drop heights, therefore they are often used in run-of-the-river power station. For this reason they are the most widely used turbine type for small-scale hydroelectric plants in Germany. The turbines are regulated via an impeller that separates the turbine from the water in the case of a fault and via adjustment of guide wheels to increase efficiency. In addition to this, further safety functions can be installed in the system in the form of an inlet valve control system and a generator brake (see page 7). The two control manifolds for adjusting impellers and guide wheels are characterized by the following structure and features:

The valve block for regulation of the impeller contains:

▶ Directional or control valve ▶ Safety valve (Fail-Safe function)

– Check valves with hydraulic unlocking – Hydraulic operated sandwich plate – Electric operated sandwich plate

▶ Adjustable inlet/outlet throttle ▶ Various speeds possible on request

The valve block for regulation of the guide wheel contains:



▶ Adjustable inlet/outlet throttle ▶ Lubricating and cooling function for rotary feed-

through (if available)



Francis Turbine Application

Francis turbines are used for medium drop heights above approx. 20 m. They are found in pumped-storage power plants and weirs. Just as with the Kaplan turbine, regulation of the turbines is performed via an impeller that separates the turbine from the water in the case of a fault. Individual adjustment of each turbine blade is also a possibility. Guide wheel adjustment is not a part of the Francis turbine. An inlet valve control system and a generator brake can also be implemented to the system as an additional function here (see page 7). The control plate for impeller adjustment is characterized by the same structure and features as the Kaplan turbine:

The valve block for regulation of the impeller contains:



▶ Adjustable inlet/outlet throttle

WRPEH: the ideal valve for turbine regulation

This control valve is a compact solution if external sen-sors for positioning are required. The valve performs with integrated electronics and electric directional feedback. As a result of its precise discrimination, the valve can move the servomotor very exact and has a defined Fail-Safe position. The WRPEH-type 4/4 directional control valve is therefore ideally suited for regulation of all the turbine types.

▶ Reliable – proven and rugged design ▶ Safe – Fail-Safe-Position of the spool in disconnected

condition ▶ Energy-efficient – no control oil needed ▶ High quality – control spool and bearing in servo quality ▶ Flexible – suitable for position, velocity and pressure

control ▶ Precise – high response sensitivity and low hysteresis ▶ Size 6, component series 3X ▶ Maximum operating pressure 350 bar ▶ Rated flow 4 ... 40 l/min (∆p = 70 bar) ▶ RE 29121



Pelton Turbine Application

Pelton turbines are used for drop heights of several hundred meters. They are found in storage power plants in high mountain regions. In contrast to the Francis and Kaplan turbines, turbine regulation is carried out via a jet deflector that separates the turbine from the water in the case of a fault. Nozzle regulation serves to increase the efficiency and normally includes 2 to 6 consumer. An inlet valve control system and a generator brake can also be implemented to the system as an additional function here (see below). The control plate of the Pelton turbine is characterized by the following features:

The valve block for regulation of the jet direction con-tains:




The valve block for regulation of the nozzles contains:






Additional Functions for all Turbine Types

The regulation system can be fitted with additional functions, as was mentioned in the previous description. These additional functions include the inlet valve control system and the generator brake. From a basic functional perspective it is not necessary to integrate these additional functions into the system, however they should be considered with regard to safety-related precautions and responsibilities:

The valve block for the inlet valve contains:

▶ Poppet valve size 6 ▶ Check valve with hydraulic unlocking as safety valve ▶ Adjustable inlet/outlet throttle ▶ Various speeds possible on request ▶ Flexed closing rate feasible

The valve block for the generator brake contains:

▶ Directional valve ▶ Pressure switch ▶ Pressure relief valve



Dimension Power Unit

Sizes Dimension (in mm)

Tank volume Accumulator volume Motor size Length Width Height

35 l 10 l 2,2 kW 750 600 800

63 l 20 l 2,2 kW 850 700 800

100 l up to 35 l 3 kW 1300 800 1800

160 l up to 3x 35 l up to 2x 7,5 kW 1400 1000 1800

Differential Cylinder for Turbine Regulation

In addition to the HPU´s, Bosch Rexroth has various cylinder series for shut-off devices and for turbine regula-tion in their range that are characterized by the following criteria:

▶ Rexroth Standards ▶ Nominal pressure 16 MPa (160 bar) / 25 MPa (250 bar)

▶ Operating pressure 25 MPa (250 bar) ▶ Piston Ø 25 up to 200 mm ▶ Piston rod Ø 14 up to 140 mm ▶ Stroke length up to 3.000 mm ▶ Other dimensions on request ▶ Different type of mountings possible ▶ Seal design M (standard) or V (higher temperatures) ▶ Piston rod end swivel head

(removable and not removable) ▶ Data sheet CDL2: RE 17326 ▶ Data sheet CDH1: RE 17332

Hei

ght

Wid

th

Length



Check List for Compact Turbine Control System

Name of project::

Type of turbine:

Country of location:

Ambient temperature:

General: Tank setting / Tank sensor system

Oil drip tray yes no

Material Carbon steel Stainless steel

Ventilation Air filter 10 µm Silica gel filter

Oil drain Oil drain plug Ball valve

Oil level tube 2 main switching contacts Analog signal 4 - 20 mA

Oil temperature Main switching contact 70 °C Analog signal 4 - 20 mA

Hand pump yes no

Painting RAL 5010 or special painting

Fitting material Stainless steel zinc plated

Piping material: Stainless steel, Voss Form

Electric:

Pressure switch / sensor wired with contact box without contact box

Special requirements



Motor-Pump-Group

Number of motors More than one motor -> size of reservoir 160 dm3

Motor-Pump-Group Standard Special requirements

Vertical mounted max. 85 dB(A) Noise level

Voltage 400/690 V Voltage

Motor speed 1480 U/min Motor speed

Performance 3 kW Performance

Volume flow 8 l/min Volume flow

Accumulator charging pressure 200 bar Accu charging pressure

System pressure 50 - 110 bar System pressure

DC - emergency pump yes no

Voltage

Performance

Volume flow

Mode of operation (S1 - S3)

Selection of accumulator Only volume of

emergency shutdown yes no

Remarks about accumulator size

e.g. number (movement of loads x and y)

Description of additional features




Guide vane control (Kaplan / Francis) / Angle control of nozzles (Pelton)

Number of cylinder

Dimension

t on t off

Capable for emergency shutdown yes no

Direction of emergency shutdown retract extend

Time of emergency shutdown

Regulation Proportional valve Control valve Solenoid valve

Set value

Weight for closing available yes no

Runner blades (Kaplan)

Number of cylinder

Dimension

t on t off





Set value

For solenoid valve: multi port swivel available yes no

Lubrication / Cooling system required yes no




Bosch Rexroth AG HydraulicsZum Eisengießer 197816 Lohr am Main, Germany Phone +49 (0) 93 52 / 18-0 [email protected] www.boschrexroth.de

© This document, as well as the data, specifications and other information set forth in it, are the exclusive property of Bosch Rexroth AG. It may not be reproduced or given to third parties without its consent.The data specified above only serve to describe the product. No statements concerning a certain condition or suitability for a certain application can be derived from our information. The information given does not release the user from the obligation of own judgment and verification. It must be remembered that our products are subject to a natural process of wear and aging.

Needle control of nozzles (Pelton)

Number of cylinder

Dimension

t on t off





Set value

Inlet valve (Francis and Pelton)

Number of cylinder

Dimension

t on t off





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Standardized Hydraulic Power Units for Small Hydro