A unit load control method adapted to rapidly changing AGC commands

Abstract

The present invention relates to a unit load control method adapted to rapidly changing AGC commands, comprising the steps of: when a thermal power steam turbine unit operates stably within a unit load control system, a industrial control computer limits and speeds up the AGC commands provided by a command receiving device. The beneficial effects of the present invention are as follows: the method of the present invention processes the received rapidly changing AGC commands by combining measurement data and logical operations, utilizes the characteristics of rapid load regulation of the steam turbine and the heat storage of the boiler; determines whether there is a regulation dead zone during the AGC regulation process, and eliminates the dead zone existing in the process of the unit responding to the AGC commands when the AGC commands fluctuate rapidly back and forth; on the basis of ensuring the safe operation of the unit, effectively improves the load regulation performance index of the unit, enhances the AGC response ability of the unit and the accuracy of load control; the method of the present invention is used for governing valve control of a generator set receiving dispatching AGC commands.

Description

Technical Field

[0001] The present invention belongs to the technical field of control of steam turbine units for thermal power generation in power grids, and particularly relates to a unit load control method adaptable to rapidly changing AGC commands. Background Art

[0002] At present, to meet the requirements of power grid power supply quality, power grid dispatching agencies implement Automatic Generation Control (AGC) for steam turbine units of thermal power generation connected to the grid, and at the same time put forward control requirements for indicators such as the AGC command response rate, response time, and control accuracy of thermal power units.

[0003] A thermal power generating unit converts the chemical energy of coal into heat energy through boiler combustion, and uses water as a working medium to absorb the heat energy and then do work in the steam turbine to drive the generator to generate electricity, thereby realizing a series of energy conversion processes from coal chemical energy to electrical energy to meet the electricity demand of society. The thermodynamic cycle system of water and steam mainly consists of equipment such as boilers and steam turbines, and converts mechanical energy into electrical energy through a generator coaxially driven by the steam turbine unit. Among them, the governing valve is the main regulating equipment set to meet the power grid load dispatching.

[0004] The overall load of the unit is controlled in real time by a Distributed Control System (DCS). The DCS performs amplitude limiting and speed limiting processing on the received AGC load command to generate a unit load command (power generation load command), and then compares it with the real-time power of the unit, adjusts the boiler fuel quantity, air supply quantity, and feed water flow rate to change the output of the boiler to meet the work demand of the steam turbine; at the same time, the DCS controls the opening of the steam turbine governing valve to change the output of the steam turbine, and then adjusts the power generation power of the unit. The DCS realizes the response to the AGC command by coordinating the energy supply and demand balance between the boiler and the steam turbine and adjusting the unit output in real time.

[0005] Currently, when designing control strategies for each unit, the main consideration is to meet the AGC assessment requirements of the "Two Rules". When the adjustment rate of the unit is higher than this assessment requirement, the unit will not incur assessment fees due to the adjustment rate. However, in the environment of frequency modulation auxiliary services in the power market, the performance competition among units comes from the difference in the adjustment performance among units. Only by trying to improve the adjustment performance of the unit itself can it gain an advantage in the game of quotation and frequency modulation income. And this puts forward higher requirements for the adjustment performance indicators of the unit.

[0006] With the advancement of the frequency regulation auxiliary service work in the power market, there have been significant changes in the characteristics of the AGC commands dispatched by the dispatcher to the units. The frequency and amplitude of the AGC commands have increased substantially compared to the past, and the operating rules have also put forward higher requirements for the AGC response performance of the units. When adjusting the output of the units using the traditional load control strategy, only simple amplitude limiting and speed limiting are performed on the received AGC load commands, which are then used as the load commands for the units. A unit load set value with a fixed ramp rate is generated and used as the load set value for both the boiler and the steam turbine for output adjustment. However, due to the lag in the adjustment of the boiler combustion system and the inertia of the unit in the steam-water system, when the unit changes load, the output of the boiler side changes slowly and cannot quickly and accurately respond to the change in power. The change in the actual load of the unit often cannot fully keep up with the change in the unit load set value, resulting in a certain degree of lag and deviation during the dynamic process.

[0007] In the conventional steam turbine load control strategy, the method of amplitude limiting and speed limiting for AGC commands has poor adaptability when AGC commands are frequently dispatched and fluctuate back and forth in the frequency regulation auxiliary service of the power market. There are many commands for rapid load increase and decrease alternatingly. It is not suitable for AGC commands with high frequency and rapid large-amplitude alternating changes in opposite directions. This lag in actual load adjustment is prone to regulating dead zones during the adjustment process, greatly affecting the load regulation performance indicators of the unit (resulting in a decline in the load regulation performance of the unit), causing indicators such as the response rate and regulation accuracy of the unit to fail to meet the requirements, affecting the assessment results of the unit's load regulation performance, and generating more electricity assessments.

[0008] Due to the rapid and frequent changes in AGC commands, the load command often receives the next AGC command in the opposite direction during the change process. At this time, the actual load of the unit has not reached the previous load command, and the direction of the actual load adjustment of the unit remains unchanged. This will result in a dead zone in the actual load adjustment of the unit for a period of time after receiving the new AGC command, and the change in the actual load shows the opposite trend to the command. Especially when the boiler combustion inertia of the unit is large and the output change is slow, it will be difficult to meet the current AGC dispatching requirements using the conventional load control strategy.

[0009] The reasons are analyzed from the control principle as follows:

[0010] 1) The AGC command (Unit Load Demand) after amplitude limiting and speed limiting is abbreviated as the ULD command. The ULD command is sent to the steam turbine control loop and is called the steam turbine load set value. The difference between the steam turbine load set value and the actual load is used as the basis for the steam turbine to change the opening of the control valve. When the actual load is less than the set value, the steam turbine increases the opening of the control valve to increase the steam intake. When the actual load is greater than the set value, the steam turbine decreases the opening of the control valve to reduce the steam intake.

[0011] 2) Additionally, the ULD instruction is obtained after limiting the amplitude and speed of the AGC instruction. After the dispatcher issues the AGC instruction, it takes some time for the ULD instruction to match the value of the AGC instruction. The actual load adjustment follows the steam turbine load setpoint. When the frequency and amplitude of the AGC instruction change too quickly, there may be a problem that the next AGC instruction is issued before the steam turbine load setpoint has changed to the previous AGC instruction. Generally speaking, the response of the actual load has a certain lag. When two consecutive AGC instructions have opposite action directions (increasing first and then decreasing, or decreasing first and then increasing), and the actual load response lags significantly, when the second AGC instruction starts to be issued to the steam turbine, the load setpoint is adjusted back to the actual load. During the same period, the action direction of the steam turbine's load adjustment is opposite to that of the AGC instruction. It can be considered that the unit's response to AGC regulation is a reverse regulation during this period, which greatly affects the AGC rate regulation of the unit.

[0012] Therefore, it is necessary to design corresponding control strategies for the rapidly changing AGC instruction to eliminate the dead zone in the load adjustment process and improve the load response ability of the unit. Summary of the Invention

[0013] The object of the present invention is to overcome the deficiencies in the prior art and provide a unit load control method that adapts to rapidly changing AGC instructions.

[0014] This unit load control method that adapts to rapidly changing AGC instructions includes the following steps:

[0015] Step 1: When the industrial control computer in the load control system of the generating unit is operating stably in the thermal power steam turbine unit, the AGC instruction provided by the instruction receiving device is subjected to amplitude limiting and speed limiting processing; after the amplitude limiting and speed limiting processing, part of the AGC instruction is used as the unit load instruction (i.e., the target value of the active power), and the remaining AGC instructions are used as the steam turbine load instruction; the steam turbine load instruction is compared with the actual power of the generator measured by the power transmitter, and the opening instruction of the steam turbine governing valve is calculated through operation (the instruction calculated for each governing valve of the steam turbine instruction. Each unit sets the opening instruction of the governing valve through the common function block of the DCS control system according to its own load regulation characteristics. Since the steam turbine control has single-valve operation and multi-valve operation, and the opening instructions of the governing valves are also different in the two operation modes, specific operation formulas cannot be given); the steam turbine load instruction is adjusted to be consistent with the actual power of the generator.

[0016] Step 2: When the industrial control computer receives a newly issued AGC instruction from the dispatching agency, compare the newly issued AGC instruction with the current steam turbine load instruction, and generate a load increase instruction lag signal or a load decrease instruction lag signal; according to the comparison result, the steam turbine load instruction tracks the unit load instruction or the actual load, generates a steam turbine load set value, and adjusts the steam turbine load until the steam turbine load set value is reached;

[0017] Step 3: After the tracking state of the steam turbine load instruction for the unit load instruction or the actual load ends, the steam turbine load instruction starts from the current value and resumes receiving the AGC instruction after amplitude limiting processing; return to repeat steps 1 to 2 to obtain the steam turbine load set value, compare the steam turbine load set value with the unit power measured in real time by the power transmitter, and the industrial control computer calculates and generates an opening instruction for the governing valve to adjust the steam turbine load instruction to be consistent with the actual power of the generator;

[0018] Step 4: After receiving the load increase instruction lag signal or the load decrease instruction lag signal, directly maintain the calculation output of the industrial control computer. The calculation output of the industrial control computer is the calculation output of the steam turbine main control instruction, and stop the measurement of the power transmitter; the steam turbine main control instruction is output through PID adjustment according to the load instruction and the actual power of the generator. Since the sudden change of the instruction and feedback deviation of the PID regulator will cause large fluctuations in the adjustment output, maintaining the output is to prevent disturbances caused by quickly switching the steam turbine load set value after receiving the lag signal;

[0019] Step 5: There is a switching function block on the industrial control computer. After the instruction switching of the switching function block is completed, the power transmitter resumes measuring the generator power, and the industrial control computer resumes calculation; perform load control according to the actual load and the processed steam turbine load set value. The load control method is that when the actual generator power lags during the unit load change process and the next AGC instruction is adjusted in the reverse direction, the steam turbine load set value is switched to the current actual generator power value to eliminate the adjustment dead zone of the steam turbine instruction and improve the AGC response rate.

[0020] Preferably, step 2 specifically includes the following steps:

[0021] Step 2.1: Compare the newly issued AGC instruction from the dispatching agency with the current steam turbine load instruction, and generate a load increase pulse signal and a load decrease pulse signal through a pulse signal generator;

[0022] Step 2.2: After receiving the load increase pulse signal or the load decrease pulse signal, the industrial control computer judges the relationship between the current unit actual load, the AGC instruction, and the current steam turbine load instruction; and generates a load increase instruction lag signal or a load decrease instruction lag signal;

[0023] Step 2.3: After receiving the load increase command lag signal or the load decrease command lag signal, process the steam turbine load command according to the AGC command, the unit load command, and the actual load to generate a steam turbine load set value.

[0024] Preferably, step 2.2 specifically includes the following steps:

[0025] Step 2.2.1: If the industrial control computer receives a load increase pulse signal, the current actual unit load is greater than the steam turbine load set value, and the current actual unit load is less than the load command target value without speed limit processing, then generate a load increase command lag signal;

[0026] Step 2.2.2: If the industrial control computer receives a load decrease pulse signal, the current actual unit load is less than the steam turbine load set value, and the current actual unit load is greater than the load command target value without speed limit processing, then generate a load decrease command lag signal.

[0027] Preferably, step 2.3 specifically includes the following steps:

[0028] Step 2.3.1: When receiving the load increase command lag signal, if the AGC command is greater than the unit load command, the steam turbine load command tracks the larger value between the unit load command and the actual load to generate a steam turbine load set value, and the steam turbine load command starts to rise at a predetermined rate;

[0029] Step 2.3.2: When receiving the load decrease command lag signal, if the AGC command is less than the unit load command, the steam turbine load command tracks the smaller value between the unit load command and the actual load to generate a steam turbine load set value, and the steam turbine load command starts to fall at a predetermined rate;

[0030] Step 2.3.3: When the conditions in steps 2.3.1 and 2.3.2 are not met, the steam turbine load command tracks the actual load to generate a steam turbine load set value.

[0031] Preferably, the tracking state of the steam turbine load command in steps 2.3.1 to 2.3.3 remains for 1 second after the tracking signal disappears.

[0032] Preferably, a control switch is set when performing speed limit processing on the AGC command in step 1; if step 2.2 triggers a load increase command lag signal or a load decrease command lag signal, the speed limit processing on the AGC command is lifted, and the tracking of the steam turbine load command is completed instantaneously; if step 2.2 does not trigger a load increase command lag signal or a load decrease command lag signal, the steam turbine load command is the AGC command after amplitude limiting and speed limiting.

[0033] Preferably, within the generator set load control system: One end of the governing valve is connected to the steam pipeline from the boiler, and the other end of the governing valve is connected to the steam inlet of the steam turbine; The steam turbine is electrically connected to the generator, and the generator is electrically connected to the power grid; The generator is also electrically connected to a power transmitter; The dispatching agency is electrically connected to the command receiving device; The governing valve, the command receiving device, and the power transmitter are all electrically connected to the industrial control computer.

[0034] Preferably, the governing valve is used to adjust the output of the steam turbine; The command receiving device is used to receive AGC commands; The power transmitter is used to measure the generator power; Among them, the industrial control computer is used to receive the AGC commands from the command receiving device and the generator set power from the power transmitter, and is also used to issue an opening command to the governing valve; The industrial control computer also performs logical judgment.

[0035] Preferably, the inputs of the switching function block in step 5 are two analog signals and one digital signal, and the output is one analog signal. The two analog signals are divided into the Yes terminal and the No terminal. When the input digital signal is 1, the analog signal at the Yes terminal is selected for output. When the input digital signal is 0, the analog signal at the NO terminal is selected for output.

[0036] The beneficial effects of the present invention are as follows: In order to improve the regulation performance index of the unit load, the present invention proposes a control method suitable for rapidly changing AGC commands. The method of the present invention processes the received rapidly changing AGC commands by combining measurement data and logical operations, and utilizes the characteristics of the steam turbine to rapidly adjust the load and the heat storage of the boiler; It judges whether there is a regulation dead zone during the AGC regulation process, and eliminates the dead zone existing in the process of the unit responding to the AGC command when the AGC command fluctuates rapidly back and forth; On the basis of ensuring the safe operation of the unit, it effectively improves the load regulation performance index of the unit, and improves the AGC response ability and load control accuracy of the unit. The method of the present invention is used for governing valve control of the generator set receiving the dispatching AGC command. Description of the Drawings

[0037] Figure 1 It is a schematic structural diagram of the generator set load control system;

[0038] Figure 2 It is a schematic diagram of the generator set load command generation loop;

[0039] Figure 3 It is a schematic diagram of the rising load pulse and falling load pulse judgment generation loop;

[0040] Figure 4 It is a schematic diagram of the rising load command lag and falling load command lag judgment generation loop;

[0041] Figure 5 It is a schematic diagram of the steam turbine load command generation loop;

[0042] Figure 6 It is the AGC regulation curve of a certain 1000MW-class unit within 5 minutes in Embodiment 2;

[0043] Figure 7 It is the AGC regulation curve of a certain 1000MW-class unit within 5 minutes after adopting the present invention in Embodiment 2.

[0044] Explanation of reference numerals: governing valve 1, steam turbine 2, industrial control computer 3, generator 4, power grid 5, power transmitter 6, command receiving device 7, dispatching agency 8. Detailed implementation manners

[0045] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to understand the present invention. It should be noted that for those of ordinary skill in the technical field, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0046] Embodiment 1

[0047] Embodiment 1 of the present application provides a unit load control method adaptable to rapidly changing AGC commands:

[0048] Step 1: When the industrial control computer 3 in the unit load control system of the generating unit is in stable operation of the thermal power steam turbine unit, the AGC command provided by the command receiving device 7 is subjected to amplitude limiting processing and speed limiting processing; after the amplitude limiting processing and speed limiting processing, part of the AGC command is used as the unit load command, and the remaining AGC commands are used as the steam turbine load commands; the steam turbine load command is compared with the actual power of the generator measured by the power transmitter 6, and the opening command of the governing valve of the steam turbine is generated through operation; the steam turbine load command is adjusted to be consistent with the actual power of the generator; the output of the steam turbine and the generator is changed, so as to achieve precise closed-loop control of the unit power; a control switch is set when performing speed limiting processing on the AGC command; the generation of the steam turbine load command is as Figure 2 shown;

[0049] Step 2: When the industrial control computer 3 receives a newly issued AGC command from the dispatching agency 8, in order to eliminate the regulation dead zone and improve the load response ability of the unit, the newly issued AGC command is compared with the current steam turbine load command (the comparison logic is as Figure 3 shown), and a load increase command lag signal or a load decrease command lag signal is generated (as Figure 4as shown); determine whether there is a regulation dead zone in the current response process of the steam turbine load command; the steam turbine load command tracks the unit load command or the actual load according to the comparison result, generates a steam turbine load set value, and adjusts the steam turbine load until the steam turbine load set value is reached;

[0050] Step 2.1: Compare the newly issued AGC command from the dispatching agency 8 with the current steam turbine load command, and generate a load increase pulse signal and a load decrease pulse signal through a pulse signal generator;

[0051] Step 2.2: When receiving the load increase pulse signal or the load decrease pulse signal, the industrial control computer 3 judges the relationship among the current actual load of the unit, the AGC command, and the current steam turbine load command; and generates a load increase command lag signal or a load decrease command lag signal;

[0052] If the load increase command lag signal or the load decrease command lag signal is triggered in Step 2.2, the speed limit processing for the AGC command is lifted, and the tracking of the steam turbine load command is completed instantaneously; if the load increase command lag signal or the load decrease command lag signal is not triggered in Step 2.2, the steam turbine load command is the AGC command after amplitude limiting and speed limiting;

[0053] Step 2.2.1: If the industrial control computer 3 receives a load increase pulse signal, the current actual load of the unit is greater than the steam turbine load set value, and the current actual load of the unit is less than the load command target value without speed limit processing, then generate a load increase command lag signal;

[0054] Step 2.2.2: If the industrial control computer 3 receives a load decrease pulse signal, the current actual load of the unit is less than the steam turbine load set value, and the current actual load of the unit is greater than the load command target value without speed limit processing, then generate a load decrease command lag signal;

[0055] Step 2.3: After receiving the load increase command lag signal or the load decrease command lag signal, process the steam turbine load command according to the AGC command, the unit load command, and the actual load to generate a steam turbine load set value;

[0056] Step 2.3.1: When receiving the load increase command lag signal, if the AGC command is greater than the unit load command, the steam turbine load command tracks the larger value between the unit load command and the actual load, generates a steam turbine load set value, and the steam turbine load command starts to rise at a predetermined rate;

[0057] Step 2.3.2: When receiving the load decrease command lag signal, if the AGC command is less than the unit load command, the steam turbine load command tracks the smaller value between the unit load command and the actual load, generates a steam turbine load set value, and the steam turbine load command starts to fall at a predetermined rate;

[0058] Step 2.3.3: When the conditions in Step 2.3.1 and Step 2.3.2 are not met, the steam turbine load command tracks the actual load to generate a steam turbine load set value;

[0059] The tracking state of the steam turbine load command is maintained for 1 second after the tracking signal disappears;

[0060] Step 3: After the tracking state of the steam turbine load command for the unit load command or the actual load ends, the steam turbine load command starts from the current value and resumes receiving the AGC command after amplitude limiting processing; return to repeat Steps 1 to 2 to obtain the steam turbine load set value. Compare the steam turbine load set value with the unit power measured by the power transmitter 6 in real time. The industrial control computer 3 calculates and generates an opening command for the governing valve 1 to adjust the steam turbine load command to be consistent with the actual power of the generator;

[0061] Step 4: To avoid the instantaneous change of the load command affecting the output of the steam turbine governing valve during the load command switching process, after receiving the load increase command lag signal or the load decrease command lag signal, directly maintain the calculation output of the industrial control computer 3. The calculation output of the industrial control computer 3 is the calculation output of the steam turbine main control command. Stop the measurement of the power transmitter 6 to avoid large disturbances during the tracking process;

[0062] Step 5: A switching function block is provided on the industrial control computer 3. After the instruction switching of the switching function block is completed, the power transmitter 6 resumes measuring the generator power, and the industrial control computer 3 resumes calculation; perform load control according to the actual load and the processed steam turbine load set value. The load control method is that when the actual generator power lags during the unit load change process and the next AGC command is adjusted in the reverse direction, the steam turbine load set value is switched to the current actual generator power value; the logic for switching judgment and generating the steam turbine load command is as Figure 5 shown; the input of the switching function block is two analog signals and one digital signal, and the output is one analog signal. The two analog signals are divided into the Yes terminal and the No terminal. When the input digital signal is 1, select the analog signal at the Yes terminal for output. When the input digital signal is 0, select the analog signal at the NO terminal for output.

[0063] As Figure 1 shown, in the generator set load control system: One end of the governing valve 1 is connected to the steam pipeline from the boiler, and the other end of the governing valve 1 is connected to the steam inlet of the steam turbine 2; the steam turbine 2 is electrically connected to the generator 4, and the generator 4 is electrically connected to the power grid 5; the generator 4 is also electrically connected to the power transmitter 6; the dispatching agency 8 is electrically connected to the instruction receiving device 7; the governing valve 1, the instruction receiving device 7, and the power transmitter 6 are all electrically connected to the industrial control computer 3.

[0064] Embodiment 2

[0065] Based on Embodiment 1, Embodiment 2 of the present application provides an application example of the unit load control method that adapts to rapidly changing AGC commands in Embodiment 1:

[0066] The AGC adjustment curve of a 1000MW-class unit within 5 minutes is as Figure 6 shown. Due to the rapid and frequent changes in the AGC command, the load command often receives the next AGC command in the opposite direction during the change process. At this time, the actual load of the unit has not reached the previous load command, and the adjustment direction of the actual load of the unit remains unchanged. This will result in a dead zone in the actual load adjustment of the unit for a period of time after receiving the new AGC command, and the actual load and the change of the command show an opposite trend (as shown in the circled part in Figure 6 ).

[0067] In response to this, the control method proposed by the present invention is used to process the command, and the control is carried out with the same initial state and the AGC command change process. The result is as Figure 7 shown, and the specific process is as follows:

[0068] 1) Before starting the simulation test, first set the values of each variable. The AGC command, load command, and actual load of the unit are all stably operating at about 900MW. At the first load change moment, the unit receives an AGC command to rise to 915MW, and the logical judgment is "increase load", but other relevant switching conditions are not met, so normal load change is carried out, and the turbine load command starts to rise at a predetermined rate.

[0069] 2) During the load change process, the AGC reissues a command to reduce the load to 897MW, and the logical judgment is "reduce load". Since the actual load changes slowly, the condition of "reduce load command lag" in the logical judgment is met. After switching the turbine load command to track the current actual load of the unit, the load reduction operation is carried out at a predetermined rate.

[0070] 3) During the load reduction process, the AGC reissues a command again to increase the load to 907MW, and the logical judgment is "increase load". Since the actual load changes slowly, the condition of "increase load command lag" in the logical judgment is met. After switching the turbine load command to the current actual load of the unit, the load increase operation is carried out at a predetermined rate.

[0071] 4) After that, the AGC command is reissued multiple times, showing a characteristic of repeated changes, and the logical judgment triggers the tracking switching circuit of multiple commands.

[0072] From the known results, according to the strategy designed by the present invention, when the AGC command is issued frequently and fluctuates back and forth, the steam turbine load command can quickly track to the current actual load and perform control, effectively eliminating the adjustment dead zone as shown in Figure 6 In this example, by adopting the load control strategy proposed by the present invention, it can always ensure that the direction of the actual load change is consistent with the dispatching AGC command, improving the regulation performance of the unit and enhancing the response ability to the AGC command.

Claims

1. A unit load control method that adapts to rapidly changing AGC instructions, It is characterized in that The following steps are involved: Step 1, when the thermal power steam turbine unit is running stably, the industrial control computer (3) in the load control system of the generator set performs amplitude limiting processing and speed limiting processing on the AGC instruction provided by the instruction receiving device (7); after the amplitude limiting processing and speed limiting processing, part of the AGC instruction is used as the unit load instruction, and the remaining AGC instruction is used as the turbine load instruction; the turbine load instruction is compared with the actual power of the generator measured by the power transmitter (6), and the opening instruction of the turbine speed regulating valve is generated by calculation; the turbine load instruction is adjusted to be consistent with the actual power of the generator; Step 2: When the industrial control computer (3) receives the AGC instruction newly issued by the dispatching mechanism (8), the newly issued AGC instruction is compared with the current steam turbine load instruction, and a load increase instruction hysteresis signal or a load reduction instruction hysteresis signal is generated; the steam turbine load instruction tracks the unit load instruction or the actual load according to the comparison result, generates a steam turbine load setting value, and adjusts the steam turbine load until the steam turbine load setting value is reached; Step 3: After the tracking state of the steam turbine load command to the unit load command or the actual load is completed, the steam turbine load command starts from the current value and re-accepts the AGC command after the amplitude limiting process; return to repeat the execution of steps 1 to 2 to obtain the steam turbine load setting value, compare the steam turbine load setting value with the unit power measured in real time by the power transmitter (6), and the industrial control computer (3) calculates and generates the opening command of the speed regulating valve (1), and adjusts the steam turbine load command to be consistent with the actual power of the generator; Step 4, after receiving the load increase command hysteresis signal or the load decrease command hysteresis signal, directly maintain the calculation output of the industrial control computer (3), the calculation output of the industrial control computer (3) is the calculation output of the steam turbine master control command, and stop the measurement of the power transmitter (6); Step 5, a switching function block is provided on the industrial control computer (3). After the switching of the command of the switching function block is completed, the power transmitter (6) resumes measuring the generator power, and the industrial control computer (3) resumes calculation; load control is performed according to the actual load and the processed turbine load setting value. The load control method is that when the actual generator power lags during the unit load change process and the next AGC instruction is reversely adjusted, the turbine load setting value is switched to the current actual generator power value.

2. According to the unit load control method adapted to the rapidly changing AGC instructions of claim 1, It is characterized in that Step 2 specifically includes the following steps: Step 2.1, comparing the AGC command newly issued by the dispatching agency (8) with the current turbine load command, and generating a load increase pulse signal and a load decrease pulse signal through a pulse signal generator; Step 2.2: After receiving the load increase pulse signal or the load decrease pulse signal, the industrial control computer (3) judges the relationship among the current actual load of the unit, the AGC command, and the current steam turbine load command; and generates a load increase command lag signal or a load decrease command lag signal. Step 2.3: After receiving the load increase command lag signal or the load decrease command lag signal, process the steam turbine load command according to the AGC command, the unit load command, and the actual load to generate a steam turbine load set value.

3. The unit load control method for adapting to a rapidly changing AGC command according to claim 2, characterized in that, Step 2.2 specifically includes the following steps: Step 2.2.1: If the industrial control computer (3) receives a load increase pulse signal, the current actual load of the unit is greater than the steam turbine load set value, and the current actual load of the unit is less than the target value of the load command without speed limit processing, then generate a load increase command lag signal; Step 2.2.2: If the industrial control computer (3) receives a load decrease pulse signal, the current actual load of the unit is less than the steam turbine load set value, and the current actual load of the unit is greater than the target value of the load command without speed limit processing, then generate a load decrease command lag signal.

4. The unit load control method for adapting to a rapidly changing AGC command according to claim 3, characterized in that, Step 2.3 specifically includes the following steps: Step 2.3.1: When receiving the load increase command lag signal, if the AGC command is greater than the unit load command, the steam turbine load command tracks the larger value between the unit load command and the actual load, generates a steam turbine load set value, and the steam turbine load command starts to rise at a predetermined rate; Step 2.3.2: When receiving the load decrease command lag signal, if the AGC command is less than the unit load command, the steam turbine load command tracks the smaller value between the unit load command and the actual load, generates a steam turbine load set value, and the steam turbine load command starts to fall at a predetermined rate; Step 2.3.3: When the conditions in Step 2.3.1 and Step 2.3.2 are not met, the steam turbine load command tracks the actual load to generate a steam turbine load set value.

5. The unit load control method for adapting to a rapidly changing AGC command according to claim 4, characterized in that: The tracking state of the steam turbine load command in Steps 2.3.1 to 2.3.3 is maintained for 1 second after the tracking signal disappears.

6. The unit load control method for adapting to a rapidly changing AGC command according to claim 3, characterized in that: A control switch is set when performing speed limit processing on the AGC command in Step 1; if Step 2.2 triggers a load increase command lag signal or a load decrease command lag signal, the speed limit processing on the AGC command is lifted, and the tracking of the steam turbine load command is completed instantaneously; if Step 2.2 does not trigger a load increase command lag signal or a load decrease command lag signal, the steam turbine load command is the AGC command after amplitude limiting and speed limiting.

7. The unit load control method for adapting to a rapidly changing AGC command according to claim 1, characterized in that, Inside the load control system of the generator set: One end of the governing valve (1) is connected to the steam pipeline from the boiler, and the other end of the governing valve (1) is connected to the steam inlet of the steam turbine (2); The steam turbine (2) is electrically connected to the generator (4), and the generator (4) is electrically connected to the power grid (5); The generator (4) is also electrically connected to the power transmitter (6); The dispatching agency (8) is electrically connected to the command receiving device (7); The governing valve (1), the command receiving device (7) and the power transmitter (6) are all electrically connected to the industrial control computer (3).

8. The unit load control method for adapting to rapidly changing AGC commands according to claim 7, characterized in that: The governing valve (1) is used to adjust the output of the steam turbine (2); The command receiving device (7) is used to receive AGC commands; The power transmitter (6) is used to measure the generator power; Among them, the industrial control computer (3) is used to receive AGC commands from the command receiving device (7) and the generator set power from the power transmitter (6), and is also used to issue an opening command to the governing valve (1); The industrial control computer (3) also performs logical judgment.

9. The unit load control method for adapting to rapidly changing AGC commands according to claim 1, characterized in that: In step 5, the inputs of the switching function block are two analog signals and one digital signal, and the output is one analog signal. The two analog signals are divided into the Yes terminal and the No terminal. When the input digital signal is 1, the analog signal at the Yes terminal is selected for output. When the input digital signal is 0, the analog signal at the NO terminal is selected for output.

Images