Turbine Regulator System
Turbine regulator is a sophisticated and reliable system for large steam turbines. The system is based on the Allen-Bradley 1756-L61 ControlLogic controller. To ensure uninterrupted control, redundancy modules are implemented to switch betweeen controllers. Main control logic was developed by experienced engineers and it has valve control and three control loops - load, pressure and speed. All important process information can be monitored and controlled by operator using user-friendly graphic windows and trends.
Turbine Regulator System consists of the following parts:
1. Controller System
Controller system is based on the Allen-Bradley 1756-L61 ControlLogix controller. It is a scalable controller solution that is capable of addressing a large amount of I/O points. Controller is placed in the backplane chassis powered by 1756-PA75 power supply. The backplane is able to serve up to eight independent modules.
Due to critical process structure and to ensure uninterrupted control operation as well as high reliability are used two base chassis with 1756-RM redundancy modules connected to separate backplanes. Redundancy modules are connected by high speed optical cable to ensure fast switching between “Active” and “Standby” controller in case of any failure.
The I/O modules are placed on three separate backplane chassis powered by the same power supply as controller chassis. Basically there are used five different types of I/O modules. There are used ControlNet 1756-CN2 modules for communication among controllers and I/O modules.
2. Valve Positioner System
Valve positioner system is based on MOOG M3000 automation system. The system is consists of programmable controller (Moog Servo Controller – MSC), software (Mood Axis Control Software - MACS) and components (servomotors, servo-drives, servo-valves, etc).
3. Turbine Rotation Speed Sensors
The RPM Transducer PR 9376 is ideally suited for contactless measurement of rotational frequency of ferromagnetic machinery components. Universal design, simple mounting and excellent characteristics enable it to be used in a wide range of applications.
Due to high resolution, fast internal electronic and the sharp edged output pulses the PR 9376 is suitable for measurement of extremely high as well as very low rotational speeds with high resolution.
The head of PR 9376 is a differential sensor consisting of two magneto sensitive semiconductor resistors which are connected in series and mounted above a small permanent magnet. Two resistors of the transducer- electronic part complete this configuration into a Wheatstone Bridge which controls a following DC-switching amplifier with fast push-pull short circuit proof output.
4. Control Logic
According to used hardware solution there is a used RSLogix 5000 software for design and configuration. Logix technology offers a unique approach — one control platform using a common control engine with a common development environment.
The logic is divided into 5 tasks according to control option:
Control Logic (Main Program);
5. Operator Interface
Below there is a picture of main operator graphics window.
All important process information is visible on the main graphic.
The window is divided into 11 parts according to scope of control. Only one part can be managed at the same time.
Those 11 parts are:
Measuring and power supply window;
High/Intermediate pressure valves control;
Turbine trip notification area;