System overview
 
SY8000 Digital Electric Hydraulic Control System is an embedded control system for turbine. It is mainly used for control of small single-extraction turbine, straight condensing turbine, back pressure cogeneration turbine or dragging turbine. The parameters under control are unit revolution, power and pressure etc. The controller timely collect related parameters such as revolution, after appropriate feedback regulate calculation, output valve position signal through servo signal output channel, to change the openness of governing valve, and ultimately maintain the parameters at a specified range. 
 
SY8000 Digital Electric Hydraulic Control System is based on high performance operation system, the maximum control cycle does not exceed 10ms. It is qualified for real-time response with its high computation ability. The programmable control technology is adopted and it is also qualified for different control needs with its flexible configuration rectify feature, SY8000 also has data storage function when power failure. Operator station or 10 inch LCD touch screen is available as graphic monitoring and operation screen. 
  
SY8000 has passed CE certification and is qualified for the following instruction:
 
Electromagnetic compatibility instruction: 2004/108/EC 
Low voltage instruction: 2006/95/EC 


 
System components 


 
SY8000 system consists of input/output channel,processor, control strategy, monitor and communication interface etc.
Input/output signal
 
Revolution signal input:

3 loops, directly receive reluctance transducer signal, the signal range is 0~10kHz, accuracy ±1Hz.
LVDT signal input:
Loop 2, directly receive 3-wire LVDT position sensor signal, accuracy ±0.5%.
 
Analog signal input:
3 loops, 4~20mA input, accuracy ±0.1%。
3 loops, 4~20mA input, accuracy ±0.1%. 24V external power supply provided.
 
Digital signal input:
12 loops, receive dry contact signal input, detecting voltage DC24V.
 
Analog signal output:
2 loops, valve position instruction, 4~20mA output, accuracy ±0.2%.
2 loops, positive and negative servo current signal output, the range is ± 10mA, ± 40mA, ± 80mA, ± 150mA, it has proportional, integral and flutter output function.
 
Digital signal output:

 

Processor

Adopt one PowerPC8247 as master CPU and three Atmega128 as slave CPU. Fast computation, excellent performance, low power consumption.


 
Control strategy
 
Control strategy is downloaded to SY8000 control kernel through Ethernet port.
 
Incase of power failure, the control algorithm and upper computer data does not lost, it will continue to run after powered.
 
For a typical extraction unit, the control cycle is limited to 10ms, operation load remains under 20%, which fully meet the requirement of turbine control system.

 


Operation screen monitor
 
Operation display and data exchange are achieved by connecting operator station with SY8000 system through Ethernet interface, or by touchscreen carried itself.


 
Communication interface
 
There are two redundant Ethernet interfaces for SY8000 system to communicate with HMI, the data refreshes every 500ms.

SY8000 system upgrades the core of the controller and control strategy configuration through Ethernet.
SY8000 system provides one Modbus interface like RS-485 interface for data communication with external system.

The internal of SY8000 system is equipped with multi-CPU for parallel work. The master CPU with excellent processor PowerPC8247 is based on control of real-time operating system, which process complex control strategy. The slave CPU is responsible for input and output channel, servo PID and over-speed protective loop for fastest response.

 

Circuit principle

Each AI channel is equipped with independent AD converter, each LVDT channel is equipped with independent signal conditioner and AD converter; each AO channel is equipped with independent DA converter, each servo channel is equipped with independent DA converter and conditioner. The revolution channel adopts high speed dedicated CPLD for real-time acquisition.

The internal of SY8000 system is equipped with multi-CPU for parallel work. The master CPU with excellent processor PowerPC8247 is based on control of real-time operating system, which process complex control strategy. The slave CPU is responsible for input and output channel, servo PID and over-speed protective loop for fastest response.

 

Control principle
 
SY8000 system accepts commands issued by human-machine interface, collects turbine revolution, power, pressure etc. to compare with corresponding parameters of SY8000 system, then puts them into corresponding loop controller for deviation calculation and PID regulation,finally outputs the opening given signal of the servomotor. After comparing the given signal with local LVDT servomotor position feedback signal, output servo control signal to electro-hydraulic valve, control the openness of servomotor i.e. control the openness of governing valve, consequently control revolution, power, pressure etc.


Application

SY8000 system can be used for thermal power unit, low temperature waste heat unit, biomass unit, turbine blower unit, feed water pump unit, turbine set for marine etc.

 

Control function

Valve position calibration 
Calibration the position of high governing valve and low pumping valve before unit start. Servomotor is controlled by servo valve during the whole stroke by servo system static test(pull valve test). The relationship betweengiven signal of valve position and servomotor lift is: given 0 to 100% lift 0 to 100%.
 
Local startup/valve manual startup/ curve startup
Local startup,valve manual startup and curve startup are available according to different requirements. For curve startup, cold, warm, hot, or extremely hot curve start can be choose according to turbine temperature when startup.
 
Revolution control

Synchronization control 
Synchronization control can be conducted after entering the range of synchronization speed, the status contact can be sent to synchronizing device, the target value can be adjusted according to the increase or reduce of the pulse issued by synchronizing device.
 
Initial load function
In order to avoid anti-power running of unit, initial load will be automatically added after unit grid.
 
Valve position control
It will automatically change into valve position control after unit grid, valve position control belongs to open loop control, operator can directly input load percentage to increase or decrease the load carried by unit.
 
Power control
After unit grid, SY8000 system conducts power control according to actual needs when there is no failure the channel, power control takes actual power of unit as feedback. The load of unit can be controlled by regulating the openness of high governing valve by PID.
 
Primary frequency control
Primary frequency control can be conducted to ensure the power quality meet the requirement of grid frequency after unit grid. When the unit speed is in the range of dead zone and the outputof frequency adjustment is zero,primary frequency control does not take action. When the speed is outside of the range of dead zone, primary frequency control takes action.
 
Steam extraction/steam supply control
Steam extraction control can be executed after unit grid and stable running with load, the target value for steam extraction pressure can be set by operator, the openness of steam extraction valve can be controlled by steam extraction pressure feedback, thus, the requirement of steam extraction hot load can be meet. Steam supply control can be executed after unit is loaded, the steam supply control of turbine can be completed by control the openness of steam supply valve.
 
Isolated net control
When unit runs alone or in small network, SY8000 conducts secondary frequency control, it is also known as isolate network running. The target load can be adjusted by hand when in isolated network running mode, or be automatically adjusted by secondary frequency function for maintaining the unit speed at 3000 r / min.
 
Remote control
When the unit grid, SY8000 system can also receive external control command, which increases or decreases pulse signal or 4 ~ 20mA analog signal.
 
Over-speed test
For initial install or overhaul, the accuracy of over-speed protection action need to be verified, each over-speed protection is required to be verified by test. There are multiple protections for the whole system, that is: 103% over-speed test, 110% over-speed test and mechanical over-speed test.
 
Strict test for main steam valve/ governing valve
Before unit start, under the condition that the revolution reaches the set value, the leak-proofness test for main valve/governing valve can be conducted to test unit idling time for identifying whether it is leak-proof.

 

Technical index

Revolution control range:

4 rpm`10000 rpm, accuracy (±1 rpm);

Load control range:

0115accuracy: 0.5%;

Speed governing droop:   

3 to 6% continuously adjustable;

Rising rate control accuracy:

1 rpm

Over regulating of revolution when rated load shedding:

5 rated revolution

Stagnant rate of control system

0.06%

Steam extraction governing droop:

010%;

System MTBF:

                                 MTBF>100000 h

System availability:  ≥99.9%

Common Mode Rejection Ratio120dBDifferential Mode Rejection Ratio≥60dB

Share the same network with other devices without requires for a single network, the grounding resistor≤2Ω

Power supply: two loops DC24V(5A),±10%, redundant supply

Maximum power: with touch screen, less than 40W; without touch screen, less than 30W;

Operating ambient temperature: with touch screen, -1045without touch screen, -1065

Storage transportation temperature: -40+85

Relative humidity: 10% RH ~ 90% RH (no condensation);

 

Operation Overview 


 
SY8000 login screen will be displayed when startup, the main screen SY8000 system is accessible after entering user ID and password.
The monitor and control screen are used forcontrol of status and parameters.
All control parameters need to be setup are listed on control parameter interface, online configuration and modification are available according to different authorities.
 
System parameter screen, set measuring range of AI (4 ~ 20mA input) channel and parameters of Modbus communication interface.
 
Channel status screen, monitor all values and status of I / O channels. 

Test screen,conduct leakage test and over-speed test before unit start.

Product selection 
  
Note: the dimension of standard cabinet is: 2200mm (H) X 800mm (W) X 600mm (D), RAL7035 and RAL9005 color available, containing two AC220V/DC24V (5A) switching power supply. There are two exchange units for engineering station and operator station.
 
Note for selection:
 
SY8000 system with touch screen cannot equip with operator station
SY8000 system with two servomotors cannot equip with feed steam control.

 

Cabinet installation
 
There is a shielding grounding copper bar (cabinet insulation) and a protective grounding copper bar installed at the back of the cabinet, the shielding layer of SY8000 system inputs and outputs cable connected to shielding grounding copper bar, SY8000 system shell and body is connected to protective grounding copper bar, the two grounding copper bars connected to concentration copper bar of electronic house through cable, after protective grounding copper bar rolled into a bus, it connects with the whole grounding network.
The cabinet was fixed on a base with four bolts, between the cabinet and the base, there is a piece of insulation pad about 5 ~ 10mm thick. 
 

 

 

 

 

 

SY8000 Digital Electric Hydraulic Control System

 

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