NB/T 10299-2019Governing system specifications of screw expander (unit) (English PDF)

3.1 Terms and definitions related to speed control system

3.1.1 Governing system

The sum of the equipment that converts the control signal into the position of the steam inlet valve in a specific way. Including speed measuring components, control system, valve actuator Wait.

3.1.2 Control system

The control system is an important part of the speed control system. The control system accepts the operating parameters of the unit, and outputs signals through logic operations. No. drive valve actuator realizes control function.

3.1.3 Control cycle

The control cycle is the execution time of the control system from data acquisition to control calculation to output signal cycle.

3.1.4 Main controller

The main controller is the control center of the control system. It completes the logic and arithmetic functions according to the configuration program set by the unit, and passes The I/O module realizes the control function. At the same time check the status of the power supply, memory, and I/O modules.

3.1.5 Availability

The ratio of the system's correct execution of the function to the total planned execution of the function, expressed as a percentage. Availability rate indicates external resources Under the premise of guarantee, the system can perform the specified functional status.

3.2 Other professional terms and definitions

3.2.1 Valve position control

Regarding the opening of the regulating valve as the adjusted amount, manually setting the opening of the regulating valve, referred to as valve control mode.

3.2.2 Speed control

Unit start control and lifting speed control.

3.2.3 Load control

Regarding the generator power as the adjusted quantity, according to the set rate of change, the generator output power is automatically controlled to be equal to the given value.

3.2.4 Pressure control

Take the inlet steam pressure (pressure in front of the main steam valve) as the adjusted amount, and adjust the steam pressure according to the set target value and rate of change.

3.2.5 Synchronization control

With the support of the speed control system, the control system for the automatic synchronization and grid connection of generators is realized.

4.1 Selection principle of speed control system

4.1.1 In order to meet the requirements of the screw expansion unit to realize start-up, speed control and load control, and to improve the reliability and economy of unit operation The speed control system should adopt a mature and reliable control system with mature technology.

4.1.2 The function, performance and overall plan of the speed control system should be compatible with the main structure of the screw expansion unit. And according to the crew Capacity, type, structural characteristics and actual application requirements determine the functions and performance indicators of the speed control system.

4.1.3 Under the condition of achieving the same function, the speed control system should be a system with high reliability, simple structure and easy maintenance. Speed regulation The design of the control system, the configuration and debugging of the control logic should be a professional unit familiar with the screw expansion unit.

4.2 Basic requirements of speed control system

4.2.1 Measuring instrument

4.2.1.1 The speed measuring probe can choose the magnetoelectric speed measuring probe, and the number of speed measuring probes should be selected reasonably according to the type of screw expansion unit.

4.2.1.2 The measuring instrument range and accuracy should meet the requirements of the unit under different working conditions. Necessary connections should be set up between the measuring instrument and the control system Wire box (box). Configure necessary local display instruments.

4.2.1.3 All meters should be qualified and used within the valid inspection period.

4.2.2 Control system

4.2.2.1 The important components of the control system, such as power supply, main controller, and communication network, should be negotiated by both the supply and demand parties. set.

4.2.2.2 The key process parameters involved in control and protection should be configured according to redundant transmitters and input channels, and the inputs should be configured in different inputs In the module; important process parameters should be redundantly configured as much as possible.

4.2.2.3 In the event of a hardware or software failure in the control system, the protection function shall not be lost and the unit shall be able to ensure safe shutdown of the unit.

4.2.2.4 The radio frequency electromagnetic field radiation immunity test installed in the indoor control system meets the general test level 2 of GB/T 17626.3 Requirements, digital wireless telephone test level 2 requirements.

4.2.2.5 The radio frequency electromagnetic field radiation immunity test of the control system installed on the industrial site meets the general test level 3 of GB/T 17626.3 Level 3 requirements, digital wireless telephone test level 3 requirements.

4.2.2.6 The voltage sag and voltage change immunity test of the control system installed indoors and industrial sites meet the requirements of GB/T 17626.11 Class 2 requirements.

4.2.3 Valve actuator

4.2.3.1 The valve actuator can be determined according to the structural characteristics and actual application conditions of the unit. The driving mode can be electric, pneumatic or Hydraulic way.

4.2.3.2 The valve actuator shall have the characteristics of fast response speed, good linearity, and high positioning accuracy to meet the operating requirements of the unit.

4.2.3.4 Switch-type actuators should only have two positions, fully open and fully closed, and adjustable actuators can be controlled at any position within the stroke range.

5.1 System structure

The control system shall consist of workstations, communication networks, main controllers, I/O modules, etc.

5.2 Cabinet

5.2.1 The enclosure protection level of the cabinet should meet the requirements of GB/T 4208-2017IP52 indoors, and meet IP56 requirements outdoors. Electronic equipment The room should meet IP42 requirements. The cabinet should be as far away as possible from high-voltage cabinets, power equipment and high-frequency equipment.

5.2.2 The weak current terminal block in the cabinet should be physically separated from the terminal block of the control and power supply circuits. All relays, backup switches and The spare contacts of the equipment should lead to the terminal block. The equipment in the cabinet has clear signs and reasonable layout, which is convenient for wiring, confluence and wiring, and other It operates.

5.2.3 The terminal blocks, cable clamps, cable routing and wiring troughs in the cabinet shall be made of flame-retardant materials.

5.2.4 The power cables, input/output cables, power cables and grounding wires in the cabinet must be routed reasonably to reduce the interference of external environmental signals. Cable interference and mutual interference between various cables.

5.2.5 The cabinet should have independent safety ground, shield ground and corresponding grounding copper bars. The speed control system can adopt the method of center ground bus Type to realize the single point grounding of the system. The cable shielding layer should be grounded at a single point in the cabinet.

5.3 Human Machine Interface

5.3.1 The operator station is a tool and means for operators to control and operate the controlled object, and should be able to monitor the unit and its auxiliary systems in real time And the operating status of the equipment, and has the following basic functions.

a) Control operation function b) Display function c) Alarm function d) Print storage function

5.3.2 The operator station should adopt advanced and mature computer workstations or industrial control computers, and the operating system should adopt open and standard operating systems.

The operating system should be equipped with at least the following equipment.

a) Display b) Processor c) Keyboard and mouse

5.3.3 The operation instructions issued by the buttons, keyboard or mouse of the operator station shall be executed within no more than 1s.

The response time from the issuance of the command to the execution of the confirmation should be no more than 2s, and the refresh cycle of the real-time data displayed on the screen should not be more than 1s.

5.3.4 The engineering station shall have the configuration, compilation, download, debugging of the control algorithm application software, as well as the setting and adjustment of control parameters, etc. basic skills.

5.3.5 If the engineer station and the operator station use the same hardware type, it can be compatible with the operator station. The engineer station should set up software Protect password, set authority management.

5.4 Main controller

5.4.1 The main controller of the redundant configuration should be switched in both directions without interference. Control and protection functions should not be lost or delayed due to redundant switching.

5.4.2 After the main controller is re-powered due to a power failure, it should be able to automatically resume normal operation without human intervention.

5.4.3 The main controller shall have complete diagnostic functions, providing diagnostic information and fault codes.

5.4.4 The memory RAM used by the main controller should ensure that at least three months of configuration data will not be lost when there is no power supply.

5.4.5 The main controller should be able to modify the adjustable parameters in the application software online, such as PID parameters, delay and pulse width time, meter values Cheng et al.

5.4.6 The processing capacity of the main controller should satisfy the control period not greater than 250ms.

5.4.7 When the main controller is running at maximum load, the load rate should not exceed 60%, and the average load rate should not exceed 40%.

5.4.8 The communication load rate of the main controller should not exceed 20%

5.5 Power

5.5.1 The redundant configuration power supply device should be able to accept two AC 220V, 50Hz single-phase power supplies, one of which is from an uninterrupted power supply (UPS). The two power sources should be able to stand by each other in the power supply device and switch automatically without disturbance.

5.5.2 The power supply device shall provide DC power supply for the control system and have a margin of 30% to 40% to meet the requirements of the equipment load. Two sets The DC power supply should be provided by two AC power supplies.

5.5.3 The power supply device shall provide AC or DC power supply for the related instruments and equipment of the speed control system.

5.5.4 The power supply device shall provide power for the I/O modules, main controllers, and communication modules in the cabinet. The power failure of any channel shall not affect it. His channel works normally.

5.6 Input/Output (I/O) Module

5.6.1 I/O modules include analog, switching, thermocouple, thermal resistance, speed, vibration, and other types of modules.

5.6.2 The I/O module should be able to complete functions such as data scanning, tuning, linearization, thermocouple cold junction compensation, quality judgment, engineering unit conversion, etc. can.

5.6.3 The I/O module should have diagnostic information such as power status, I/O channel status, open and short circuit of analog signals, and input signal overrun. Information, and can be displayed through LED instructions.

5.6.4 The input channels and output channels of the I/O module and their working power supply should all be isolated from each other. Both the input signal and internal circuit Electrical isolation or other isolation. The switch output signal adopts electrical isolation output.

5.6.5 The power supply circuit of the I/O module should be equipped with an appropriate fuse, and the replacement of the fuse does not need to remove other components.

5.6.6 The I/O module should not damage the power supply and the entire system when 250V DC voltage or AC peak-to-peak voltage is applied by mistake.

5.6.7 Each I/O point margin is not less than 10%, and the I/O module slot margin is not less than 10%.

6.1 Control method

6.1.1 Automatic control

According to the operating parameters of the unit, the automatic control unit starts, speeds up, and loads the whole process according to the set starting curve. In automatic control Human intervention can also be carried out in this way.

6.1.2 Operator automatic control

6.1.2.1 Operator automatic control is the basic control method of the unit. The operator sets the target speed and target load according to the status of the unit. Closed loop control of unit speed and load.

6.1.2.2 Operator automatic control can also be incorporated into automatic control mode as a means of human intervention under automatic control mode.

6.1.3 Manual control

Manual control means that the operator manually controls the opening of the regulating valve of the unit to achieve load open-loop control, also known as valve position control.

6.2 Control function

6.2.1 Speed control

Including start control, speed increase control and constant speed control. The speed should be adjustable within 3% of the upper and lower rated speed The requirements of the drive synchronization device (driving generator set); the speed should be able to be adjusted within the agreed range that meets the demand unit).

6.2.2 Load control

Including rising and falling load control and stable load control. When the generator is running in isolation, from no load to full load (including both)

The speed is stable under all loads; when the generator is connected to the grid or runs in parallel with other generators, the load can be input to the grid stably.

6.2.3 Pressure control

6.2.3.1 Constant pressure control. change the opening of the regulating valve to increase and decrease the load, and keep the fresh steam pressure constant.

6.2.3.2 Sliding pressure control. Keep the opening degree of the regulating valve unchanged or basically unchanged, and the load changes with the change of the new steam pressure.

6.2.4 Synchronous control (driving generator set)

Receive the synchronization signal from the synchronization device to realize the synchronization and grid connection of the unit.

6.3 Protection function

6.3.1 When the speed control system fails, the speed signal fails, the power supply of the speed control system is lost, or the unit safety monitoring device sends a signal When the time, the speed control system trip protection signal should be generated.

6.3.2 In any control mode, the unit protection function should not be withdrawn, and the protection "switching" button should not be set.

6.4 Test function

6.4.1 Under the circumstance of not hindering the operation of the unit, the main steam valve and regulating valve shall be locally tested to check whether the valve can move freely.

6.4.2 The supplier shall specify the restriction conditions, test period and method of valve activity test.

6.5 Interface function

6.5.1 Synchronization interface (drive generator)

6.5.2 Data communication interface

6.5.3 Safety monitoring device interface

6.5.4 The remote diagnosis interface can be negotiated between the supplier and the buyer.

7.1 Acceptance

7.1.1 The supplier is responsible for the installation, testing and commissioning of the speed control system, and the buyer can specify in the contract to require participation in "observation" and "see During the test process, the test results and data of the speed control system shall be jointly approved by the supplier and the buyer.

7.1.2 Acceptance shall be carried out after the random group of the speed control system has been running stably for a period of time, and the specific time shall be negotiated by both parties.

7.1.3 The assessment of system functions and performance shall be carried out within the warranty period. The warranty period shall start from the completion of the acceptance and last for 12 months.

7.1.4 The statistics of the availability rate are carried out after the speed control system is put into normal use, and the timing start time can be negotiated between the supplier and the buyer. Statistics The scope is limited to the system itself, excluding field devices such as transmitters and actuators connected to the system.