Vibration control, monitoring and diagnostics system for hydraulic units

Stationary system for vibration control, monitoring and diagnostics of hydraulic units is used for constant technological and safety control, diagnostics of vibrational and mechanical parameters of hydraulic units and auxiliary equipment of hydroelectric power stations in accordance with the applicable requirements.

This automation and measurement system has two levels:

First level

primary transducers and digital sensors

Second level

software level

System functions

  • Full self-testing of measuring equipment 
  • Diagnostics of possible faults
  • Data and system performance information saving
  • Long-term functioning and possibility of fast recovery in the course of operation
  • Possibility of system further expansion in the course of its operation
  • Stable operation in the case of power supply failure
  • Automated adjustment of channels characteristics
  • Events log

Operating principles

Vibration control, monitoring and diagnostics system for hydraulic units is scalable and has distributed structure.

The sensors are mounted in the control points of hydraulic turbine and are united into measuring lines. The hydrophones are installed into the lid of hydraulic unit turbine, vibration velocity transducers – at the blades of guiding unit, seismic sensors – near the bearings (3 sensors per each bearing), cavitation sensors and hydrophones – near the entrance hatchway.

Then the measuring lines are equipped with interface converters, providing data transfer from digital sensors to the server via Ethernet interface and further data archive storage. One or more measuring lines are further united into data acquisition nodes equipped with interface converters  ZET 7176, synchronization modules ZET 7175 for controllers system time and server time synchronization, flash modules ZET 7173, and, if necessary, with wireless data transfer modules ZET 7177.

Digital sensors have metrological self-check function, which enables in-place verification of the devices within the scope of the measuring system, which guarantees stable performance and high precision of the measured data obtained.

Information from data acquisition nodes is also transferred to work station, where data processing and visual representation is performed.

Work station has a user-friendly system of events notifications for the operator.

Mechanical disturbing forces may occur in the hydraulic units in the following cases:

  • shaft disbalance;
  • misalignment;
  • inner tension of the shaft;
  • bearings dry friction or friction of rotating parts against fixed parts.

In most cases oscillations of hydraulic units shafts are attributed to pilot bearings dry friction and inner gaps. That is exactly why vibration control at the bearings location is of utmost importance for hydraulic unit integrity control.

In the case of lack of grease or big gaps between the shaft and the shaft bearing or friction of rotating parts against fixed parts there occur self-oscillations. The self-oscillations occur at any speed of shaft rotation and are equal to natural oscillation frequency of the system.

First harmonics frequencies of mechanical disturbing forces are as follows:

    • disbalance of rotating parts (n/60): 0,8 – 15,0 Hz;
    • shaft misalignment (n/60 and 2n/60): 0,8 – 30,0 Hz;
    • dry friction (2÷5)nnom: 5 – 60 Hz.

Digital seismometers ZET 7156 are used for hydraulic units shaft vibration and whipping control at the areas of bearings locations. Seismometers ZET 7156 can register displacement of several hundredth of µm at low frequencies.

АЧХ ZET 7156 и ZET 7152-N

Vibration frequency level at the blades of the turbine is considerably higher than that of the hydraulic unit in general. It is caused by the fact that the vibration is amplified by rotational frequency. For the purpose of vibration control at turbine blades area, digital accelerometers ZET 7152-N are used. If compared to ZET 7156, ZET 7152-N  has higher precision of vibration level measurements at the frequency range over 10 Hz.

Advantages of the System

Self-check

metrological self-check of system’s measuring components

Installation

fast and simple mounting at the area of measurements performance

Compact dimensions

it is possible to place data acquisition nodes in constraint environments

Diagnostics

LED indication enables visual diagnostics

Digital communication lines

with interference protection

10 years warranty

high reliability and stable performance

Composition of the system

Below you can see composition of monitoring and vibration control system for a single hydraulic unit.

Basic configuration
Item  Function Amount
Measuring component
Digital seismometer ZET 7156 shaft vibration and displacement control at bearings area 9 pcs.
Digital accelerometer ZET 7152-N blade vibration control in vertical and horizontal direction 4 pcs.
Digital hydrophone ВС 314 oscillatory pressures measurement and control 4 pcs.
Digital cavitation sensor ZET 7140-R cavitation noise level measurement 1 pc.
Data acquisition node
Electrical cabinet for data acquisition and transfer module 1 pc.
Interface converter ZET 7176 data transfer from digital sensors to server and workstation by Ethernet interface 1 pc.
Synchronization module ZET 7175 digital sensors data timing synchronization 1 pc.
Flash module ZET 7173 loop recording of the data registered by digital sensors 1 pc.
Server and workstation 
Server acquisition and long-term storage of the registered data
(included into server configuration and task-specific software)
1 pc.
Workstation of the operator visual representation of system operation
(included into PC configuration and task-specific software)
1 pc.
SCADA-system ZETVIEW automation of control and monitoring process
Additional configuration
GSM data transfer module  ZET 7177 additional data transfer channel to the server upon request
Services 
Design and survey works Monitoring system design and development
Training and supervision-installation activities Customer’s personnel training and supervision-installation activities
Start-up and commissioning On-site start-up and commissioning

In accordance with the applicable technical requirements, in the course of hydraulic engineering installation operation it is necessary to provide safety by means of monitoring of technical state, foundations and building structures of hydraulic engineering installations.

Structural health monitoring system enables automated monitoring of the following parameters of hydraulic engineering installations:

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