| Various Power Plant Control Sub-Systems |
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The Process | Control Sub-systems | Case Study | Power Project Reference List
Click the TABS for further information Four Main Objective of Power Plant Automation1. Automatic Detection
2. Automatic Modulation
3. Remote Control and Program Control
4. Automatic Protection
Sub-Control Functions Matrix
Abbreviation Used
DAS (Data Acquisition System)
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Boiler Part
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Turbine Part
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FSSS (Furnace Safeguard Supervision System)
( Boiler )
- Burner Management: The control of the burner oil gun and ignition process.
- Burner Management: To prevent the burning flame in boiler furnace from extinguishing.
- Boiler Safeguard: Preventing explosion or implosion of the boiler due to over-pressure etc.
- Boiler Safeguard: The surveillance and control measures of the automation system.
FSSS consist of two types of system: Burner Management System and Furnace Safeguard Supervision System. The design of FSSS system is accord with US standards, NFPA8502 National Fire Protection Association Standard and other relevant technical standards.
BMS (Burner Management System)
- Burner oil gun and ignition process (Start/Stop Sequence Control)
- Pulverized-Coal combustion control (Start/Stop Sequence Control)
- Pulverized-Coal Machine Control System
Features:
- The whole automation and control process from Start, Blast-blow, Burning, until the steadily operation of burner.
- It can also control through “stage by stage, sequence start”, and fulfill the automatic control of the burner.
- Burner control function in normal operating mode or RB “reburn burner” operating mode.
FSS (Furnace Safety System)
- Comply with the NFPA8502 standards.
- Burner blow/purge
- Oil fuel system leakage test
- Emergency Trip (MFT (Master Fuel Trip) /OFT (Oil Fuel Trip) Function
Safeguard and Supervision Features:
- To monitor the continuous operation of the boiler
- To produce Oil Fuel Trip (OFT) or Master Fuel Trip (MFT) signal rapidly and accurately.
- Though hardwire logic, carry out the relevant protection action for OFT/MFT signal.
- To put the emergency trip signal to BMS system and finish corresponding protection action.
- When MFT occurs, to keep the air intake of the boiler, removes the flammable object in the burner, hearth. Before satisfying relevant permitting conditions, prevent the fuel from entering the burner.
- Manual MFT trip function.
- Automatic record and display the “Tripping Reason”.



ECS (Electrical Control System)
( Generator | Common )
The electrical system control for the DCS system is divided into two subsystems:-
- Generator Electrical System
- Common Electrical System
Common Electrical System
The common electrical system is “common” and shared by the two generator units. Each generator is controlled by its own DCS system. The DCS system controlling of one of the generator unit shall NOT affect the normal operation of the other generator unit. The DCS systems of the two generator units has full supervision and control, however, the DCS systems has to be interlock to ensure only one DCS system has the operational and control rights. The operational and control rights can switch in between the two DCS system smoothly.
Turbine Generator Electrical System includes:-
- Transformer Unit 500 KV circuit breaker, Isolated Switch
- Generator’s De-Magnetic Switch
- AVR (automatic voltage regulator) control
- Auto Quasi-synchronization; ASS
- High voltage operation, Backup branch circuit breaker
- 6KV Bus main operating power branch switch
- 6KV Bus backup operating power branch switch
- 6KV Plant factory used, rapid cut-off device
- Low voltage transformer 6KV; 380V and 380V sectional switch
- Low voltage lighting transformer 6KV; 380V switch and lighting; maintenance transformer 380V sectional switch
- Safety phase of operating; backup branch switch
Common Electrical System includes:-
- Start/Spare Transformer 220 KV breaker, Disconnecting Switch, Loaded Voltage Regulation Switch
- 6kv common branch switch (OA,OB)
- Common transformer(#1, #2) 6KV, 380V and 380V branch switch
- Factory transformer (#1, #2) 6KV, 380V and 380V branch switch
- Chemical transformer (#1, #2) 6KV, 380V and 380V branch switch
- Factory common transformer (#1, #2) 6KV switch, 6KV feeder switch
Digital Electro-Hydraulic Control
(Steam Turbine)
The steam turbine digital electro-hydraulic control system is the most important functional subsystem of the turbine power generator. It utilized pure electric and high-pressure fuel-oil or low-pressure turbine oil hydraulic servo system component forming the Digital Electro-Hydraulic Control System (DEH). The control system is highly reliable and easy to operate, easy to maintenance, flexible, with features and design focusing on the redundancy of key components, self-diagnostic on every sub-modules, and risk reduction.
The primary function of the DEH system provides the load and speed control of the turbine. It also includes a number of other parameters of control such as over-speed protection, thermal stress, monitoring theturbine generator parameters, the start/stop sequence control, and other functions. In addition, DEH system also fully adapt to the other incident and events occurring during the process. This includes unit/crew incident working conditions (such as RB), start/stop running process, and other process requirements.
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Primary Control Function: Load Control and Speed Control
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Other functions: Turbine Start/Stop sequence control, Over-speed protection, thermal stress calculation, turbine parameter monitor etc.
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Redundancy of Key components
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Self-diagnostic on every sub-modules
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Risk reduction design.
Control Function
Speed Control
Based on the thermal status of the turbine, turbine usage, inlet condition, and turbine life consumption, the DEH system determines its related speed-up ratio and automatically adjusts gradually to its required speed.
- Speed adjustment range from 50 ~ 3600 rpm
- Speed control loop and control precision of ± 1rpm (rated speed)
- Maximum increment/decrement of not more than 0.15% of the rated speed
Load Control
DEH system provides automation control from "initial load” to “full load”. DEH system can provide fast respond to the request of the primary frequency controller. There are three control modes: “Valve Control”, "Pressure Control" and “Power Control”.
- Power Control precision:± 0.5% (steam parameter in a stable condition)
- Static characteristics of speed ranging from adjustable rate, Setting scope of3% to 6%
- Power change in the range of ± 1.5% ~ ± 12%
- Frequency changes in the range of ± 0.025 Hz ~ ± 0.25 Hz
- Settling rate of 3% to 8%
Load rejection control functions
In order to improve the dynamic stability performance or the over-speed of the steam turbine generation during system power failure, the DEH system set up following the rejection load control functions:
- Instantaneous fast clearance, Continued fast clearance
(taking into consideration of the turbine’s adaptive capacity control) - Speed limit (OPC)
Over Speed Protection Trip
- Turbine speed is up to 110% of rated speed, DEH system sends out Protection Trip Order to Emergency Trip System device, and produces a series of protection actions.
- The protection action of the turbine is finished by ETS. For example, close the master steam door and medium-pressure regulated door…
- In normal operation mode of generating set, DEH system has provide 103%, 110% over speed testing means, which can examine whether the function of over-speed, trip system are normal.
Thermal Stress Calculation
Automation Turbine Control
ATC system can coordinate with the following control system and realize the whole automatic control in start–up process of the turbine group.
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Turbine control system
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Drain Pump Control System
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Turbine Bypass Control System
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Generator Excitation control system
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Generator Automatic Synchronization System
The Control Function of Turbine ATC
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Under least manual intervention, with a possible most speed-up, from Turning Gear speed to synchronous speed progressively, and incorporated into the generating net.
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The whole process control from initial load to normal load.
The Concrete Function
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The essential test before starting, guarantee the start condition of automatic start-up;
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The calculation of the speed-up and supervisory
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Speed and speed-up control function
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Stress calculation and supervisory function
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Incorporated Control of generating set
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Turbine’s load rate and load control
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Over speed protection control
Operation Mode
DEH system accept the order and signal of Coordinate Control system, can realize the following modes safely and economically
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Boiler coordinate mode
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Boiler Follow
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Turbine Follow
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Constant Pressure Operation
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Slide Pressure operation
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Manual Operation
DCS control system accords to the principle of step and layer control. When the upper control system is in trouble, it can change to the lower control system. The operator can also choose one operation mode. For example, Operator Automatic Operation mode; turbine automatic control.
Reliability Design
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Utilization of appropriate technology in redundancy with self-diagnostic of each sub-modules to ensure the most highly reliable DEH system.
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Triple measurement scheme (1-out-3, 2-out-3) on the most important analog I/O (speed, power, pressure, etc.)
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Redundancy on the most important digital I/O.
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All the important analog and digital I/O are installed with proper isolation.
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All the operators input instructions are verified and check according to the appropriate rules setup.
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Utilizing hard-wired connections to receive the TSI Turbine body temperature signal and measurement
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Any failure of individual component will not affect the operation of the whole system.
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The system is totally protected even when there is power supply interruption sensors failure, or motor drive failure.
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The control system is designed accordance with the principle of"protection against failure” and "safety auto lock-up".
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Static and dynamic test were conducted on a target model via simulation and a closed-loop system DEH controller before implementation.
Boiler Micro Electro-Hydraulic Control
Functions
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Automatic speed increase control
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Free Speed and load control
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The coordination control with water-supply control
- Motor-driven Feed Pump and Steam-driven Feed Pump switching control
- Motor-driven Feed Pump and Steam-driven Feed Pump input/stop control
- Parallel Operation Control
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Interlock Protection
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Valve Testing
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Under the online state, small steam turbine trip test, distant test of inlet valve and control valve.
Supervisory information system
for the plant level
With the improvement of the automation technology in power plant, it is crutial to collect, analysis and utilize production information. Therefore, SIS system has appeared. The role of SIS is to provide realtime information for the security andeconomical operation of the power plant.
Based on the experience of implementing power plant system, Hollysys Company has developed the Supervisory Information System for the plant level -- HOLLiAS SIS. It provides specialized solution for automatic production and management in the power plant.
Through the high-speed network, HOLLiAS SIS connects with DCS system of each generating sets, obtains the production date and equipment state of generating set in real time, set up unified production information database. It is easy to learn the operational state of generating sets equipment, analyze the operation and overhaul, cost of power plant, and offer information for economic operation management in power plant.
The Function of HOLLiAS SIS
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To collect real-time production information of generating sets, so the product staff can obtain product information promptly, accurately and wholly.
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Set up the unified data platform.
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keep the large amount of real-time and historical production data of the generating sets for a long time
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Convenient to analysis and utilizing.
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Using the specialized function subsystem
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Analyze the existing data
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Discover the problem in the production
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Guide the administrative decision for economical operation.
Main Function Modules
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The Scrutiny of Production Process
In real-time database, to finish the function such as collect, save, dispatch of on-the-spot data, and realized the supervision and management of whole production process. -
Performance Calculation
To calculate various efficiency of the whole power plant online, including boiler, turbine and assistant system etc, and various losses, including coal, water, electric power, and heat loss etc, through these performance index, we can describe the operation economic situation of the generating set. -
Equipment Life Management
To do comprehensive analysis and assessment to online information and off-line testing data of the equipment, and carry out status supervision and diagnose to its life status, provide relevant equipment assess, life loss, recent testing plan, operation/maintenance/ change decision etc to the power plant, the power plant makes the decision on maintenance and implement. -
Vibration Measures and Trouble Diagnose
Through the testing of vibration, judge the trouble of generating sets, to improve the operation dependability of the generating set. It gathers the collect of Vibration Signal Acquisition, Time-Domain and Frequency-Domain Analysis, trouble diagnosis and network technology, adopts multiple new technologies, with higher comprehensive performance indexes. -
Load distribution in power plant
To set up the mathematical model of load distribution, choose suitable mathematics optimal method, then realize the load optimal distribution in the parallel operation process that multiply generating sets in whole plant. -
Electricity Generation Costs Analysis
Taking into the consideration of distribution of fixed cost, variable cost and electricity generation cost, to calculate the current electricity generation cost of power plant in real time, combine other factors of electric network , provide data support for offering price, and competitive price. -
Operation Guidance
To the turbine’s status, especially hot stress is online supervisory and control, realize the reasonable loss of sets life, ant optimize the start/stop speed of the generating set, in order to improve the security and economy of the turbine. Through small index calculation and loss analysis, evaluate the operation of generating sets, find the problem and give essential operation guidance to operation personnel, optimize the operation process of the generating set, achieve the cost minimization and benefit maxima.
Management Information System
Along with the reform in electric power industry, it is the unceasing target of electric power enterprises to enhance production efficiency, working efficiency, and reduces operation cost with information technology. Therefore, Hollysys company has developed the Power Plant Management Information System HOLLiAS MIS that conformed to the reality of power enterprises.
This system absorbs advanced management though from home and abroad, in the practice of electric power enterprises, integrates the human resources, wealth, material, information together, enhances working efficiency with maximum and reduces the cost.
This system can realize the seamless connection with different DCS, and provides the solution for electric power industry from the automatic control floor of production to enterprise upper management. The system intends to improve enterprise management, improve the economic efficiency of enterprise, meanwhile improve and enhance the management level of enterprise, impels the modernization of management, serves for the ultimate objective, enhance the market competition ability and survivability.
Main Functional Modules
Production management
Product planning and statistic, operation management, safety management, DCS gateway
Equipment management
Equipment account management, equipment reliability management, equipment defect, protection fix value and warning, Non-Leakage management
Supply management
Fuel management, stock management, purchase management
Financial Management
Account management, Account Payment Management, Fixed Assets Management, Salary Management, Cost Calculation, teller management
Assistance management
Human resource management, Insurance management, environmental protection management, simulation chart management
Office automation
OA system, Archives management
System Characteristic
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Conforms to the management standard of electric power industry
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Tailor the unified report form of electric power industry
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Automatic production operation ticket
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Realize seamless connection with DCS gateway
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Provides the unified management of work tickets
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Strict control the water, mist and dust etc, environment factors
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Carries on equipment defects promptly
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Accurate real-time operation log management
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Carries on the automatic settlement to the fuel
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Effective control to large, minor repair projects
HOLLiAS MIS system is the comprehensive operation management system in electric power industry. It based on network platform of Intranet/Internet technology, uses the operation pattern of C/S, B/S, and is a management information system with advanced technology, practicable economy, reliable safety and excellent opening. It has implemented successfully in many electric power enterprises.









