river level regulation Industrial Controls panel manufacture linear potentiometers
retrofit of obsolete equipment
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Industrial Control Systems

Case Studies using SCADA, PLCs and Distributed Control Systems

Control of 400kV Grid Switchgear

JK Controls Ltd designed industrial control systems for a CCGT power station in the UK, using SCADA systems to operate remote circuit breakers over a 2km fibre optic link.  The communications used dual pairs of single mode optical cores to provide secure data transmission between the local and remote areas.

Mitsubishi PLCs were used for gathering the plant information and for commanding the switchgear.  A PC running Citect SCADA provided the operator interface in the control room.  The system was also integrated into the control room mimic display panels for duplicate indication of the switch states.

A severe installation constraint was imposed by the section of the Grid System only being available for maintenance for 2 days every 18 months. The system was to replaced existing obsolete equipment, which was still operational.  JK Controls therefore designed and manufactured custom interface cards with plug and socket connectors which were compatible with the connectors of the obsolete equipment.  Furthermore the legacy equipment operated at 50v dc positive earth, so the bespoke interface cards incorporate level shifting and optical isolation circuitry to match the industry standard 24v dc technology of the PLC.  The output contacts are all duplicated for security.

The process control system was designed, built and thoroughly tested prior to change-over from the old system, enabling completion in the 2 day outage period allowed.  From enquiry to commissioning the task was completed in only 3 months.
Schematic showing SCADA industrial control system, linked to PLCs via fibre optics
Cubical housing custom built interface cards and PLC 
Power Station End                    Switchgear End

Power station relocation and DCS

Design and implementation of animated mimic screensOur client is removing a power station from UK for rebuild at a steel works in the Far East.  The blast furnace turbine driven air blowers are from a different site.  JK Controls is engaged in re-equipping all of the instrumentation and control services.  The disparate collection of second user plant presents a unique set of problems in establishing successful control.  For example, the boilers are of different size and the steam conditions required by the several turbines differ considerable.  Unreliable grid supplies puts special demands on the controls to be able to sustain essential air and electricity supplies from the steam driven plant in the event of loss of external supplies.  Economic and environmental constraints demand that the blast furnace waste gas is optimally consumed within the power station boilers.  JK Controls is sourcing and coding a new distributed control system (DCS) and mimic screens, sourcing new and second user instrumentation, retrofitting obsolete equipment, designing all systems and control room, commissioning the final installations and training staff.

Boiler - Generator control

Our client has successfully retrofitted a complete control system to 2 x 500MW boiler/turbine units, using modern distributed control system (DCS) technology.  Our personnel were engaged to provide expert assistance with advice, design effort and commissioning of the control structure.  The operational needs of the national grid system and the commercial constraints which now pertain to power plant operation, set onerous demands upon load and frequency regulation.  We custom designed the boiler and turbine controls and built a computer simulation of the appropriate sections of plant.  The controls were then optimized off line using the model to achieve near optimum control prior to committing to the plant for final commissioning.  The plant is now providing close control of load and frequency response together with on time run up to target load, as required by Grid Control.

Crash Test Rig

Our client (TRL Ltd) operates a range of transport research and test facilities.  A new facility has been built for testing components such as child seats, wheel chair securing attachments, F1 racing car nose cones, etc.  JK Controls Ltd. have designed, built and commissioned the controls for operating the test and recording results.

A trolley carries the sample under test, which is projected along a track by strong rubber cords using a patented design.  The trolley is then brought to rest by means of a rapid deceleration apparatus or by impact with a solid steel wall, dependent upon the type of test being carried out.

JK Controls supplied a PLC and SCADA based control system to handle the test set-up, test sequencing, safety interlocking, data gathering and post-test recording of results.  The system uses Microsoft Access for data set-up and results history, Citect SCADA for operator interaction, and Mitsubishi Q series PLC for data I/O and control.  The screen appearances of the software systems are customised to give a consistent ‘house’ look.

The operator is able to type in a desired impact speed, the number of cords and the diameter of the cords, as well as many other menu based test set-up characteristics.  The trolley is weighed and the point of initial impact registered.  The trolley is winched back and the system then carries out a calibration sequence using force and position measurements with calculations to determine the desired release point for the trolley that will enable the final speed at impact to be within 1% of the desired value.  At the onset of impact a high speed measuring phase is started which gathers depth of impact data, checks its validity, stores the data and records the greatest depth of impact prior to rebound.  Position measurement was a challenge due to the rapid movement, deceleration and non-contact requirement of the application.  We researched several methods of measurement and carried out extensive tests, finally settling upon a Sick-Stegmann laser system with rapid update.  This enables measurement of impact depth to within 2mm and location of the trolley over the full track length of 22 meters.

On completion of the test further data is recorded regarding maximum acceleration prior to impact and measured impact speed.  The stored energy at release and the energy actually imparted at impact are calculated to determine the efficiency and hence refine the calibration of subsequent tests.

JK Controls built the control panels and custom designed electronic systems for speed measurement and calibration.

Crash Test Rig Control Cabinet SCADA Screen

River Level Control systems within Flood Defence

JK Controls Ltd have carried out specialist control systems projects for the National Rivers Authority and the Environment Agency, undertaking design, procurement, building, installation, commissioning and documentation of measurement and control schemes for weirs, gates, penstocks, pumps, screens, water intakes etc.

Where many individual installations on a river have been designed and built by an array of different contracting organisations, there will inevitably be a diversity of designs and methods amongst them.  JK Controls has taken the best features and eliminated the worst to improve the overall operation and reliability of the installations.

  • In the absence of detailed information for existing installations, analysis of the river level control software and hardware has been undertaken, enabling reverse engineering and production of drawings and manuals for operation and maintenance function.  Where existing control schemes have been of poor design we have analysed the problems, written reports, re-designed and improved the systems.  

  • In order to thoroughly verify automatic control systems under all operational and fault conditions physical models have been built, thus enabling creation of control schemes that are fully working and tested prior to fitting at site and so reducing commissioning time.
HMI and PLC responding to river level simulation to control model penstock.         Flood defence control panel
Development set up using model penstock       On site commissioning of river level controls
  • Apart from the plant control there is also the neglected issue of operator "friendliness".  Care is taken to ensure that HMI displays, messages and other operator interactions are managed in an ergonomic way to minimize confusion.

  • JK Controls Ltd also carries out routine and breakdown maintenance of the controls to achieve high availability of the Client's assets.

  • We can supply, install and maintain telemetry systems. 

 

Contact Information: e-mail to info@jkcontrols.co.uk, or telephone +44 1732 522353  

Registered Address: JK Controls Ltd, The Barn, 65 High Street, East Malling, Kent, ME19 6AJ.  Reg. No. 3073964

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