Control system and method for heat supply RB of high-back-pressure thermal power generating unit

Abstract

The invention belongs to the technical field of automatic control of a thermal power plant, and discloses a control system and method for a heat supply RB of a high-back-pressure thermal power generating unit. The state of a heat supply circulating pump is automatically detected, an RB (rapid load reduction) function is automatically triggered when abnormality is detected, the emergency situation of tripping of the heat supply circulating pump can be rapidly responded, and the heat supply circulating pump can be rapidly controlled. Delay possibly caused by manual operation is avoided, and dependence on manual judgment and operation in emergency is avoided, so that the possibility of human errors is reduced, and the operation process is simpler, more convenient and safer. According to the automatic RB triggering function, the unit load can be rapidly reduced under the condition that the circulating pump trips, and equipment overload or other potential safety hazards caused by shutdown of the heat supply circulating pump are avoided, so that equipment safety is protected, system fluctuation caused by misoperation or slow response is reduced, and the overall stability and reliability of a heat supply system are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of automatic control of thermal power plants, and particularly relates to a control system and method for heating RB of a high back-pressure thermal power unit. Background Technique

[0002] With the gradual increase in the number of high back-pressure thermal power heating units, some new problems have also emerged in the safety of heating units. For example, if the heating circulating water pump trips abnormally and the cooling capacity of the unit's circulating water is insufficient, it will have a greater impact on the vacuum of the condenser, and even cause the unit to trip.

[0003] To enhance the safety of heating units, in the case of abnormal operation of the heating circulating water pump, it is necessary to quickly reduce the load, reduce the cooling water volume of the condenser, and ensure that the unit vacuum is at a safe level. Currently, the units generally adopt the method of manually operating to reduce the load, often resulting in untimely operation, affecting the rapid decline of the unit load, and even causing unsafe events due to improper operation. There is an urgent need to design a heating RB logic for high back-pressure units to achieve the function of automatically reducing the load of the unit and improving the emergency handling ability of the unit.

[0004] The RB function of the unit, which is the abbreviation of RUNBACK, refers to when the actual power generation of a thermal power unit is restricted due to the tripping of a major auxiliary machine, in order to adapt to the output of the equipment, the control system forcibly reduces the unit load to the load target value that the still-operating auxiliary machines can bear. This function is called the load reduction due to auxiliary machine failure. A perfect RB control strategy is based on the stable input of the coordinated control system. It should coordinate each subsystem internally (i.e., the coordinated control system) to ensure a balanced transition of the operating conditions; externally, it should coordinate the DCS and DEH control systems to quickly and smoothly reduce the load within the allowable range of the unit output.

[0005] The RB functions commonly configured in thermal power units mainly include forced draft fan RB, induced draft fan RB, primary air fan RB, air preheater RB, coal mill RB, feed water pump RB, etc. Basically, no thermal power heating units are configured with heating RB functions. Summary of the Invention

[0006] The purpose of the present invention is to overcome the safety risks existing in manually operating to reduce the load in the case of tripping of the circulating water pump of the high back-pressure heating unit, and provide a control system and method for heating RB of a high back-pressure thermal power unit.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a control method for heating RB of a high back-pressure thermal power unit, including the following steps: Obtain the switch signals of the heating circulating pumps in at least two high back-pressure thermal power units; Judge the working state of each heating circulating pump according to the switch signals; If at least one of the heating circulation pumps is in a stopped state, then a signal for triggering the RB function is generated.

[0008] A further improvement of the present invention is that when there is one standby heating circulation pump, and only one heating circulation pump is in an operating state, then the standby heating circulation pump is started.

[0009] A further improvement of the present invention is that when there is one standby heating circulation pump, and only one heating circulation pump is in an operating state, and the start of the standby heating circulation pump fails, then a signal for triggering the RB function is generated.

[0010] A further improvement of the present invention is that the signal for triggering the RB function includes stopping the corresponding coal mill or powder feeder according to the number of pulverized coal burners required for the target load of the high back-pressure thermal power unit.

[0011] A further improvement of the present invention is that the signal for triggering the RB function includes switching the coordinated control of the high back-pressure thermal power unit from the boiler-following coordinated control mode to the turbine-following coordinated control mode.

[0012] In a second aspect, the present invention provides a control system for the heating RB of a high back-pressure thermal power unit, including: A switch signal acquisition module, configured to acquire the switch signals of the heating circulation pumps in at least two high back-pressure thermal power units; A working state judgment module, configured to judge the working state of each heating circulation pump according to the switch signals; An action trigger module, configured to generate a signal for triggering the RB function when at least one of the heating circulation pumps is in a stopped state.

[0013] A further improvement of the present invention is that it includes a standby heating circulation pump start module, configured to start the standby heating circulation pump when there is one standby heating circulation pump and only one heating circulation pump is in an operating state.

[0014] A further improvement of the present invention is that it includes a shutdown control module, configured to stop the corresponding coal mill or powder feeder according to the received signal for triggering the RB function and in combination with the number of pulverized coal burners required for the target load of the high back-pressure thermal power unit.

[0015] A further improvement of the present invention is that it includes a unit coordinated control strategy module, configured to switch the coordinated control of the high back-pressure thermal power unit from the boiler-following coordinated control mode to the turbine-following coordinated control mode according to the received signal for triggering the RB function.

[0016] In a third aspect, the present invention provides an electronic device, including a memory and a processor. The memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of a control method for heat supply RB of a high back-pressure thermal power generating unit are realized.

[0017] Compared with the prior art, the present invention has the following beneficial effects: By automatically detecting the status of the heat supply circulation pump and automatically triggering the RB (rapid load reduction) function when an abnormality is detected, the present invention can quickly respond to the emergency of the heat supply circulation pump tripping, avoid the possible delays caused by manual operation, and avoid relying on manual judgment and operation in an emergency, thereby reducing the possibility of human error and making the operation process simpler and safer. The automatically triggered RB function of the present invention can quickly reduce the unit load in the case of the circulation pump tripping, avoid equipment overload or other potential safety hazards caused by the shutdown of the heat supply circulation pump, thereby protecting the equipment safety, reducing system fluctuations caused by operation errors or slow reactions, and improving the overall stability and reliability of the heat supply system. In summary, due to the automatic control, the present invention can respond to the heat supply circulation pump tripping situation faster and more accurately, improve the unit's rapid load reduction ability, ensure the safety and reliability of the high back-pressure heat supply unit, and can effectively reduce the economic losses caused by safety accidents or equipment damage.

[0018] Furthermore, the present invention adds an automatic start function for the standby heat supply circulation pump. When the running heat supply circulation pump fails or shuts down, the system can automatically start the standby pump to ensure that the heat supply circulation is not interrupted, thereby improving the overall reliability of the system. By quickly starting the standby heat supply circulation pump, it is possible to avoid a sudden drop in system pressure or heat supply interruption caused by the shutdown of a single circulation pump, thereby reducing the risk of unit shutdown or the necessity to start the RB function and ensuring the normal operation of the unit.

[0019] Furthermore, in the case where the standby heat supply circulation pump cannot be started, the system automatically triggers the RB function to quickly reduce the unit load. This mechanism can effectively prevent too low pressure in the heat supply system or other potential safety hazards caused by the failure of the heat supply circulation pump, ensuring that the system still operates safely under abnormal conditions. The present invention is equivalent to setting multiple protection levels in the heat supply system. When the first protection (starting the standby pump) fails, the RB function serves as a second protection measure to ensure that the system can still stably and controllably reduce the load or shut down when multiple failures occur, thereby ensuring the stability and safety of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flowchart of the present invention; Figure 2 is a system diagram of Embodiment 1; Figure 3It is the heating RB trigger logic diagram of a certain power plant in Embodiment 2; Figure 4 It is the heating RB trigger logic diagram of a certain power plant in Embodiment 3; Figure 5 It is the control logic diagram of the coal mill for heating RB of a certain power plant in Embodiment 4; Figure 6 It is the system block diagram of Embodiment 5. Specific implementation manners

[0021] To further understand the content of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for explaining the present invention rather than limiting it. In the following text, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0022] In this application, DCS refers to Distributed Control System, which means a distributed control system; DEH refers to Digital Electric Hydraulic Control System, which means a digital electro-hydraulic control system for steam turbines; RB refers to Runback, which means a rapid load reduction; BF refers to Boiler follow, which means a boiler-following coordinated control mode; TF refers to Turbine follow, which means a turbine-following coordinated control mode; DO refers to Digital output, which means a digital quantity output; DI refers to Digital input, which means a digital quantity input.

[0023] See Figure 1 , a control method for heating RB of a high back-pressure thermal power unit, including the following steps: S1, obtain the switch signals of the heating circulation pumps in at least two high back-pressure thermal power units.

[0024] S2, judge the working state of each heating circulation pump according to the switch signals.

[0025] S3, if at least one of the heating circulation pumps is in the shutdown state, trigger the RB function action signal.

[0026] See Figure 2 , a control system for heating RB of a high back-pressure thermal power unit, including: A switch signal acquisition module, configured to acquire the switch signals of the heating circulation pumps in at least two high back-pressure thermal power units.

[0027] A working state judgment module, configured to judge the working state of each heating circulation pump according to the switch signals.

[0028] An action trigger module, configured to trigger an RB function action signal when at least one of the heating circulation pumps is in a stopped state.

[0029] Embodiment 1: A control system for heating RB of a high back-pressure thermal power unit, comprising: A switch signal acquisition module, configured to acquire switch signals of heating circulation pumps in at least two high back-pressure thermal power units.

[0030] A working state judgment module, configured to judge the working state of each heating circulation pump according to the switch signals.

[0031] An action trigger module, configured to trigger an RB function action signal when at least one of the heating circulation pumps is in a stopped state.

[0032] A standby heating circulation pump starting module, configured to start a standby heating circulation pump when there is one standby heating circulation pump and only one heating circulation pump is in an operating state.

[0033] A shutdown control module, configured to shut down corresponding coal mills or powder feeders according to the received RB function action signal in combination with the number of pulverized coal burners required for the target load of the high back-pressure thermal power unit.

[0034] A unit coordinated control strategy module, configured to switch the coordinated control of the high back-pressure thermal power unit from a boiler-following coordinated control mode to a turbine-following coordinated control mode according to the received RB function action signal.

[0035] Embodiment 2: Refer to Figure 3 , this embodiment configures two heating circulation pumps with a capacity of 50%.

[0036] Two signals, namely "switch closing Aon" and "switch opening Aoff", are sent out by the 6KV switch cabinet of the A heating circulation pump and are hard-wired into the protection system control cabinet through the switch quantity input card (DI point) of the DCS system; two signals, namely "switch closing Bon" and "switch opening Boff", are sent out by the 6KV switch cabinet of the B heating circulation pump and are hard-wired into the protection system control cabinet through the switch quantity input card (DI point) of the DCS system. The "switch closing Aon" signal and the "switch opening Boff" signal are judged by logical "AND" to obtain the "B heating circulation pump shutdown" signal, and the "switch closing Bon" signal and the "switch opening Aoff" signal are judged by logical "AND" to obtain the "A heating circulation pump shutdown" signal. Then, the "A heating circulation pump shutdown" signal and the "B heating circulation pump shutdown" signal are judged by logical "OR" to obtain the "one heating circulation pump tripped" signal, triggering the heating RB function action signal.

[0037] Embodiment 3: In this embodiment, 2), a unit equipped with three heat supply circulation pumps with a capacity of 50% operates in a mode of two running and one standby.

[0038] Two signals, namely "Switch closing A on" and "Switch opening A off", are sent out from the 6KV switch cabinet of the A heat supply circulation pump and are hard-wired into the protection system control cabinet through the digital input card (DI point) of the DCS system.

[0039] Two signals, namely "Switch closing B on" and "Switch opening B off", are sent out from the 6KV switch cabinet of the B heat supply circulation pump and are hard-wired into the protection system control cabinet through the digital input card (DI point) of the DCS system.

[0040] Two signals, namely "Switch closing C on" and "Switch opening C off", are sent out from the 6KV switch cabinet of the C heat supply circulation pump and are hard-wired into the protection system control cabinet through the digital input card (DI point) of the DCS system.

[0041] The signals of "Switch closing A on", "Switch opening B off" and "Switch opening C off" are judged by logical "AND" to obtain the signal of "Only the A heat supply circulation pump is running".

[0042] The signals of "Switch closing B on", "Switch opening A off" and "Switch opening C off" are judged by logical "AND" to obtain the signal of "Only the B heat supply circulation pump is running".

[0043] The signals of "Switch closing C on", "Switch opening B off" and "Switch opening A off" are judged by logical "AND" to obtain the signal of "Only the C heat supply circulation pump is running".

[0044] Then, the signals of "Only the A heat supply circulation pump is running", "Only the B heat supply circulation pump is running" and "Only the C heat supply circulation pump is running" are judged by logical "OR" to obtain the signal of "Only one heat supply circulation pump is running", and the heating RB function action signal is triggered after a delay of 5 - 8 seconds (waiting for the unsuccessful connection start of the standby pump).

[0045] Embodiment 4: Taking a 300MW coal-fired unit of a certain power plant as an example, the boiler is a subcritical drum boiler, equipped with 5 layers of tangentially fired once-through burners, and 5 direct-fired coal mills respectively correspond to the A - E layer burners from bottom to top. The DCS system RB control strategy is as follows: 1) According to the operation combination of the pulverized coal burners, retain the number of pulverized coal burners required for the corresponding target load (60% of the rated load), and trip the corresponding coal mill.

[0046] 2) The unit coordinated control is switched to the TF sliding pressure mode, and the regulating systems such as air supply, induced draft, feed water, and steam temperature automatically control the output.

[0047] Pulverized coal burner control strategy: DCS judges based on the combination of pulverized coal burners in operation and retains three of the five layers of pulverized coal burners. Figure 3 As shown, the specific logical steps are: Step 1: remove the E coal mill; Step 2: If the four coal mills A, B, C, and D are in operation, the D coal mill will be cut off with a delay; if one of the four coal mills A, B, C, and D is not in operation, it will not be cut off.

[0048] Unit coordinated control strategy: Step 1: The coordinated control of the units is switched from BF to TF sliding pressure mode, with the boiler master controlling the load and the turbine master controlling the inlet pressure.

[0049] Step 2: The load setting value is reduced from the actual heat load before RB to 60% of the rated load at a certain rate. To ensure stable boiler combustion, the boiler main control is switched to manual and the coal feeder is switched to a certain fixed output.

[0050] Step three: Control the inlet pressure of the turbine by adjusting the turbine regulating valve. The pressure setting value is obtained according to the load-pressure curve, and the changing rate of the pressure setting value is a certain value.

[0051] Step 4: Control the air volume by adjusting the fan blades. After an RB occurs, the air volume setpoint is determined based on the load setpoint and the actual load, ultimately set at 60% of the rated load. The fan blades are adjusted accordingly.

[0052] Step 5: The induced draft, feed water and other regulating systems automatically control the output; the cooling water regulating valve is overrun and closed, and normal steam temperature regulation is resumed after 60 seconds.

[0053] Step 6: To prevent the main automatic control loops (including boiler master control, steam turbine master control, combustion control, feed water control, air volume control, negative pressure control, primary air pressure control, steam temperature control, deaerator water level, etc.) from losing their regulating function due to a large deviation between the regulated variable and the given value, the manual interlock for the large deviation cut-off of each main control loop shall be released when RB occurs.

[0054] Embodiment 5: See also Figure 6 As shown, the present invention also provides an electronic device 100 for controlling a method for supplying heat RB to a high back pressure thermal power unit; the electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on the at least one processor 102, and at least one communication bus 104.

[0055] The memory 101 can be used to store the computer program 103. By running or executing the computer program stored in the memory 101 and invoking the data stored in the memory 101, the processor 102 implements the steps of the control method for high back-pressure thermal power unit heating RB described in Embodiment 1. The memory 101 may mainly include a program storage area and a data storage area. Among them, the program storage area can store an operating system, application programs required for at least one function (such as a sound playback function, an image playback function, etc.); the data storage area can store data created according to the use of the electronic device 100 (such as audio data, etc.). In addition, the memory 101 may include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices.

[0056] The at least one processor 102 can be a Central Processing Unit (CPU), or can also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 102 can be a microprocessor or the processor 102 can also be any conventional processor, etc. The processor 102 is the control center of the electronic device 100, and connects various parts of the entire electronic device 100 through various interfaces and lines.

[0057] The memory 101 in the electronic device 100 stores multiple instructions to implement a control method for high back-pressure thermal power unit heating RB. The processor 102 can execute the multiple instructions to thereby implement: Obtain the switch signals of the heating circulation pumps in at least two high back-pressure thermal power units; Judge the working state of each heating circulation pump according to the switch signals; If at least one of the heating circulation pumps is in a shutdown state, trigger the RB function action signal.

[0058] Embodiment 6: If the modules / units integrated in the electronic device 100 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-described embodiment methods of the present invention, it can also be completed by a computer program instructing relevant hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-described method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, and read-only memory (ROM, Read-Only Memory).

[0059] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0060] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of flows and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the specified functions in Figure 1 one or more of these flows Figure 1 or a combination of multiple flows and / or blocks

[0061] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the specified functions in Figure 1 one or more of these flows Figure 1 or a combination of multiple flows and / or blocks

[0062] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus, causing a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one flow Figure 1 one flow or more flows and / or blocks Figure 1 steps for implementing the functions specified in one block or more blocks.

[0063] Finally, it should be noted that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention fall within the protection scope of the claims of the present invention.

Claims

1. A control method for heat supply RB of a high back-pressure thermal power unit, characterized in that, Including the following steps: Obtain the switch signals of the heating circulation pumps in at least two high back-pressure thermal power units; Judge the working state of each heating circulation pump according to the switch signals; If at least one of the heating circulation pumps is in the shutdown state, trigger the RB function action signal.

2. The control method for heat supply RB of a high back-pressure thermal power unit according to claim 1, characterized in that When there is one standby heating circulation pump, if only one heating circulation pump is in the running state, start the standby heating circulation pump.

3. The control method for heating RB of a high back-pressure thermal power unit according to claim 1, wherein, When there is one standby heating circulation pump, if only one heating circulation pump is in the running state and the start of the standby heating circulation pump fails, trigger the RB function action signal.

4. The control method for heat supply RB of a high back-pressure thermal power unit according to claim 1, wherein The RB function action signal includes shutting down the corresponding coal mill or feeder according to the number of pulverized coal burners required for the target load of the high back-pressure thermal power unit.

5. The control method of high back-pressure thermal power unit heat supply RB according to claim 1, characterized in that, The RB function action signal includes switching the coordinated control of the high back-pressure thermal power unit from the boiler-following coordinated control mode to the turbine-following coordinated control mode.

6. A control system for heat supply RB of a high back-pressure thermal power unit, characterized in that, Including: A switch signal acquisition module for obtaining the switch signals of the heating circulation pumps in at least two high back-pressure thermal power units; A working state judgment module for judging the working state of each heating circulation pump according to the switch signals; An action trigger module for triggering the RB function action signal when at least one of the heating circulation pumps is in the shutdown state.

7. The control system for heat supply RB of a high back-pressure thermal power unit according to claim 6, characterized in that, Including a standby heating circulation pump start module for starting the standby heating circulation pump when there is one standby heating circulation pump and only one heating circulation pump is in the running state.

8. The control system for heating RB of a high back-pressure thermal power unit according to claim 6, characterized in that, Including a shutdown control module for shutting down the corresponding coal mill or feeder according to the received RB function action signal in combination with the number of pulverized coal burners required for the target load of the high back-pressure thermal power unit.

9. The control system for heat supply RB of a high back-pressure thermal power unit according to claim 6, characterized in that, Including a unit coordinated control strategy module for switching the coordinated control of the high back-pressure thermal power unit from the boiler-following coordinated control mode to the turbine-following coordinated control mode according to the received RB function action signal.

10. An electronic device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the control method for heating RB of a high back-pressure thermal power unit according to any one of claims 1 to 5.

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