Improved regulation and control method for intelligent primary frequency modulation of thermal power energy storage condensation water

Abstract

According to the thermal power energy storage condensation water intelligent primary frequency modulation improved regulation and control method, auxiliary regulation and control of primary frequency modulation are involved through condensation water throttling, the optimal sliding pressure operation curve is corrected in real time, a primary frequency modulation control preliminary optimization strategy is adopted, and a primary frequency modulation method integrated with condensation water intelligent regulation and control is established; by designing the switching of the system and the input permission rule of a control loop, the architecture of the intelligent condensed water regulation and control system is improved, the intelligent control logic of the intelligent condensed water regulation and control system is optimized, the rapid regulation and control performance of unit power is improved, and the problem of hysteresis in the steam production process of a coal-fired unit is solved; the problem that the power change is difficult to respond quickly when the unit increases or decreases the fuel quantity and the water supply quantity through a coordinated control system is solved, and the large-disturbance primary frequency modulation performance and AGC response quality of the unit are improved; the primary frequency modulation response speed of the generator set is improved, the power grid frequency stability is maintained, and the power grid primary frequency modulation assessment requirement is met.

Description

Technical Field

[0001] The present application relates to a method for improving primary frequency regulation of thermal power generation, and in particular to a method for improving and regulating intelligent primary frequency regulation of thermal power energy storage condensate, belonging to the technical field of improving and regulating frequency regulation of power grids. Background Art

[0002] With the continuous increase in grid capacity, the continuous increase in the rated power generation of thermal power units, and the improvement of grid quality requirements on the power consumption side, the stability of grid power supply frequency, as an important indicator of power quality, has received increasing attention. Abnormal conditions such as abnormal blocking of DC interconnection lines and fault disconnection of generator sets will impact the normal operating frequency of the grid. There is a clear intermittent nature in the generation of new energy sources such as wind power and solar power, which further exacerbates the fluctuation of grid frequency. When the grid frequency deviates, the generator sets need to adjust the power quickly to maintain the stability of the grid frequency. The delay in the control of the grid dispatching system and the unit AGC system will not be able to meet the requirements of grid frequency stability. The investment and implementation of the primary frequency regulation function of the grid-connected units can effectively deal with grid frequency instability. The speed of the primary frequency regulation response of thermal power units plays an important role in improving the safety and stability of the grid frequency. In order to improve the quality of power supply to the grid, it is necessary to vigorously promote the improvement and optimization of the primary frequency regulation performance of each generator set to improve the stability of grid operation and enhance the grid's ability to resist accidents.

[0003] Due to the lag in the steam production process of coal-fired units, when the power demand of the power grid changes, it is difficult for the unit to quickly respond to the power change by increasing or decreasing the amount of fuel and water supply. At present, the primary frequency regulation performance of thermal power units is determined by the heat storage capacity of the boiler. For large-unit direct-current boilers, the larger the unit capacity, the less heat storage per unit load, and the boiler's heat storage response load capacity decreases accordingly. Thermal power plants are also affected by objective factors such as fluctuations in the quality of the power supply coal and the low online measurement accuracy of the air-powder system. At a faster load rate, the control system is difficult to ensure the stability of the unit's parameters, which restricts the response quality of the power grid AGC command; on the other hand, the traditional single static sliding pressure operation curve set according to the manufacturer's data or operation optimization test does not consider the impact of changes in environmental parameters, heating and industrial steam; in addition, the theoretical sliding pressure optimization results are often not directly used, and additional throttling bias needs to be added artificially to meet the requirements of the primary frequency regulation of the power grid and the AGC response quality, resulting in large throttling losses.

[0004] The traditional primary frequency regulation method using boiler heat storage as a means, although optimized by configuration logic and parameter configuration, its load adjustment speed has been difficult to meet the grid assessment standards, especially in the low load stage, due to insufficient boiler heat storage, the primary frequency regulation generally has the problem of substandard response speed and frequency regulation amplitude, and even the primary frequency regulation action is incorrect and the power contribution is negative. Therefore, it is necessary to deeply explore the energy storage of thermal power units, and jointly intervene in the primary frequency regulation control optimization strategy on both sides of the steam turbine and boiler to improve the primary frequency regulation performance of the unit.

[0005] The intervention optimization and control of the condensate system is to adjust the condensate flow rate, the steam extraction volume entering the deaerator and the low-pressure heater, and make full use of the thermal energy storage on the steam turbine side of the unit to change the load of the generator set. The existing technology has few control strategies for the intervention optimization and control of the condensate system, and there is still a lot of room for optimization in practical applications.

[0006] The problems that need to be solved by the existing thermal power condensate primary frequency modulation control method and the key technical difficulties of this application include:

[0007] (1) With the continuous increase in grid capacity, the continuous increase in the capacity of generator sets and the improvement of users' requirements for power quality, grid frequency, as an important indicator of power quality, has an increasing demand for its stability. The primary frequency regulation response speed of existing generator sets can no longer meet the requirements for maintaining grid frequency stability. The characteristics of DC boilers with complex control objects and insufficient heat storage are still prominent. At present, the units are required to strictly meet the requirements of AGC, primary frequency regulation and other indicators. Coordinated control and traditional primary frequency regulation schemes cannot meet the requirements. Due to the lag in the steam production process of coal-fired units, when the power demand of the grid changes, it is difficult for the units to quickly respond to power changes by increasing or decreasing the amount of fuel and water supply through the coordinated control system. The current thermal power units cannot fully meet the primary frequency regulation assessment requirements of the grid. There is a lack of auxiliary control methods for primary frequency regulation through condensate throttling. The existing technology does not combine real-time correction of the optimal sliding pressure operation curve, and cannot improve the rapid control performance of the unit power, resulting in poor primary frequency regulation performance and AGC response quality of the unit under large disturbances. It is impossible to coordinate and take into account the operation safety, stability, economy and rapid control ability of the unit. The accuracy and timeliness of primary frequency regulation of thermal power units are relatively poor.

[0008] (2) The existing technology of "condensate throttling" for thermal power generating units is still immature in terms of load response control, especially for 600MW supercritical units. There is a lack of solutions for intelligent condensate control to assist in improving load response speed, and it cannot be applied to supercritical unit control systems. There is a lack of targeted testing on the intelligent condensate control characteristics, and there is a lack of the relationship between condensate flow and unit load, deaerator liquid level, etc., which makes it impossible to quickly control the load of supercritical units. Condensate control has some problems in improving the load response speed of the unit's primary frequency regulation, such as causing large fluctuations in the water levels of the deaerator and condenser, resulting in instability of some operating conditions and parameters of the unit, and a short control effect cycle. When actually applied to the primary frequency regulation of the unit, condensate throttling cannot avoid a large impact on parameters such as the deaerator liquid level and condenser water level, and cannot ensure the safety of the unit operation.

[0009] (3) The existing thermal power condensate primary frequency regulation strategy cannot actively adjust the condensate flow rate to change the low-pressure steam extraction volume, cannot enable the unit to solve the early response of the primary frequency regulation load when the fuel response is delayed, cannot quickly respond to the primary frequency regulation and peak regulation requirements of the power grid, and cannot instantly increase the unit output; lacks the optimization of the sliding pressure operation curve, and the high-pressure control valve cannot be fully opened or maintained at a large opening during turbine operation, and the throttling loss of the high-pressure control valve is relatively high; the energy-saving control architecture based on the condensate intelligent control system and deep sliding pressure cannot correct the optimal sliding pressure operation curve in real time according to environmental and parameter changes, and lacks the use of the condensate intelligent control system model, resulting in weak rapid control capability of the unit power, poor primary frequency regulation effect, and inability to timely and accurately diagnose and handle power grid power supply frequency failures, which is not conducive to ensuring the safety and stability of the power system. Summary of the invention

[0010] The present application uses condensate throttling to intervene in the auxiliary regulation of primary frequency regulation, and combines it with real-time correction of the optimal sliding pressure operation curve, adopts a preliminary optimization strategy for primary frequency regulation control, establishes a primary frequency regulation method that incorporates condensate intelligent regulation, improves the condensate intelligent regulation system architecture, optimizes the intelligent control logic of the condensate regulation system, and improves the rapid regulation performance of the unit power by designing the system's switching and control loop input permission rules, thereby solving the problem of lag in the steam production process of the coal-fired unit. When the power demand of the power grid changes, the unit cannot quickly respond to power changes by increasing or decreasing the amount of fuel and water supply through the coordinated control system, thereby improving the unit's large disturbance primary frequency regulation performance and AGC response quality; meeting the current increasing power grid capacity, increasing single-unit capacity of generator sets, and increasing user requirements for power quality, improving the stability of the power grid frequency as an important indicator of power quality, and improving the primary frequency regulation response speed of the generator set, which is conducive to maintaining the stability of the power grid frequency and meeting the primary frequency regulation assessment requirements of the power grid.

[0011] In order to achieve the above technical effects, the technical solutions adopted in this application are as follows:

[0012] Improve the control method of intelligent primary frequency regulation of thermal power energy storage condensate. Through the intervention of condensate throttling in the auxiliary control of primary frequency regulation, combined with real-time correction of the optimal sliding pressure operation curve, adopt the preliminary optimization strategy of primary frequency regulation control, establish a primary frequency regulation method integrating condensate intelligent control, improve the system architecture of condensate intelligent control by designing the system switching and control loop input permission rules, optimize the intelligent control logic of condensate control system, improve the rapid control performance of unit power, improve the unit large disturbance primary frequency regulation performance and AGC response quality;

[0013] The improved control strategy is to actively adjust the condensate flow rate to change the low-pressure steam extraction volume, so that the unit can solve the early response of the primary frequency regulation load when the fuel response is delayed, quickly respond to the primary frequency regulation and peak regulation requirements of the power grid, and instantly increase the unit output; at the same time, combined with the optimization of the sliding pressure operation curve, the high-pressure control valve is fully opened or maintained at a large opening during the operation of the turbine, and the throttling loss of the high-pressure control valve is minimized; based on the energy-saving control architecture of the condensate intelligent control system and deep sliding pressure, the optimal sliding pressure operation curve is corrected in real time according to the environment and parameter changes, and the condensate intelligent control system model is adopted to improve the rapid control capability of the unit power;

[0014] This application targets 600MW supercritical units, analyzes the characteristics of supercritical boiler units, establishes a solution for intelligent condensate control to assist in improving load response speed, builds control strategies and optimization solutions, establishes a model for the influence of the intelligent condensate control system on load parameters, analyzes the flow changes of the condensate control system, and the corresponding changes between the unit load, deaerator liquid level, condenser water level, and low-pressure water level operating parameters, to achieve the unit condensate system auxiliary rapid optimization control application.

[0015] Preferably, the primary frequency modulation control preliminary optimization strategy A is:

[0016] 1) Optimization based on improving the quality and availability of primary frequency modulation signals: the speed signal is used instead of the frequency signal to improve the accuracy of the system; in addition, a starting enhancement loop is set in the system. When the speed deviation is 2 revolutions, the primary frequency modulation frequency deviation load command is 0MW. When the speed deviation is 2.1 revolutions, the primary frequency modulation frequency deviation load command output is 3MW. The corresponding relationship between the speed difference from 2.1 revolutions to 11 revolutions and the load command is linear, which improves the response speed of the primary frequency modulation;

[0017] 2) Optimization of DEH primary frequency modulation circuit in low load section:

[0018] By increasing the valve position correction factor change corresponding to the set main steam pressure of the unit in the control logic, the frequency modulation valve position instruction is amplified to achieve the corresponding frequency difference for the frequency modulation valve position amplitude requirement. The actual speed of the unit generates a reference frequency modulation valve position instruction after passing through the frequency modulation dead zone and the preset speed inequality function. After setting the main steam pressure correction function, the pressure-corrected frequency modulation valve position instruction is finally generated.

[0019] A pressure-corrected frequency-regulating valve position command feedforward loop is added to the DEH integrated valve position command control loop. When the unit is controlled in power closed loop, pressure closed loop or DEH is controlled in remote control mode, the frequency-regulating valve position feedforward command is used to quickly respond to the grid's requirements for the unit's primary frequency regulation speed.

[0020] 3) Solution to the problem of synchronization of frequency modulation action between CCS side and DEH side: The control logic uses the turbine speed signal and the rated speed deviation signal as the synchronization signal of frequency modulation action between CCS side and DEH side. The speed deviation signal is directly introduced into the primary frequency modulation control loop of the coordination control loop. The speed deviation signal is converted into the corresponding primary frequency modulation load instruction through a preset function. The primary frequency modulation frequency deviation load instruction summarizes the unit load instruction and directly goes to the turbine master control and boiler master control loops.

[0021] DEH and CCS use the same speed deviation signal to ensure the synchronization of primary frequency regulation between DEH and CCS. At the same time, the unit responds quickly to the fluctuation of grid frequency deviation and meets the continuity and stability of positive contribution of primary frequency regulation load when the grid frequency deviation fluctuates with large amplitude and long cycle.

[0022] Improvement of the main control power circuit of the steam turbine on the CCS side: By improving the frequency modulation load instruction and the main steam pressure deviation locking circuit in the main control circuit of the steam turbine on the CCS side, the stability of the unit load response is increased and the pullback effect on the primary frequency modulation action on the DEH side is avoided;

[0023] Avoid the CCS side from pulling back the frequency regulation control loop on the DEH side when the unit performs a frequency regulation action, improve the main control loop of the steam turbine on the CCS side, add a direct loop of the frequency regulation load command, and avoid the load command pulling back the frequency regulation action; add a lock on the current main steam pressure deviation control loop after a frequency regulation action occurs, and slowly release the main steam pressure deviation control loop after the frequency regulation action disappears for a period of time, so as to avoid the disturbance of the steam turbine load command due to the main steam pressure fluctuation of the unit, and maximize the satisfaction of the power grid's requirements for the durability and stability of the frequency regulation load.

[0024] Preferably, the primary frequency modulation control preliminary optimization strategy B is:

[0025] 1) The DEH side directly applies the frequency deviation signal to the turbine speed regulating valve command. The DEH primary frequency modulation power component should directly enter the OSB feedforward output, cancel the inertia link, and quickly change the turbine speed regulating valve opening;

[0026] 2) Both sides of the turbine and boiler respond to the primary frequency modulation together. The DEH speed deviation signal is directly introduced into the CCS system. At the same time, the frequency modulation load command is directly passed through the turbine main control and boiler main control loop without delay, which speeds up the rate at which the primary frequency modulation frequency deviation load command is output to the power command, and speeds up the combustion response speed on the boiler side;

[0027] 3) When the primary frequency regulation is in low-frequency operation and the unit is not in the process of load reduction, the main steam pressure deviation loop is locked, or the weight function value in the main steam pressure correction control strategy of the steam turbine is reduced to reduce the reverse regulation on the steam turbine side;

[0028] 4) After the first frequency modulation action, the main steam pressure deviation increases, weakening the frequency modulation load command action amplitude, and after the first frequency modulation action occurs, the current main steam pressure deviation control loop is locked;

[0029] 5) When the primary frequency modulation is in low frequency operation, increase the primary air pressure setting value; use the powder storage system to speed up the boiler combustion response speed;

[0030] 6) During a frequency modulation action, reduce the inertia time of the water supply command control logic.

[0031] 4. According to the improved control method of intelligent primary frequency regulation of condensate water for thermal power energy storage in claim 1, it is characterized by incorporating a primary frequency regulation method of condensate water intelligent control: by adjusting the condensate water flow rate to change the low-pressure steam extraction amount, the amount of steam entering the steam turbine to do work changes, so that the unit can quickly increase the output when the boiler fuel response lags, thereby responding to the peak load and frequency regulation requirements of the power grid;

[0032] When the unit is loaded, the condensate flow rate is reduced, the amount of steam work in the turbine is increased, the low-pressure steam extraction volume is reduced, the unit load is increased, and the condensate flow rate is reduced, which will cause the deaerator liquid level to drop and the condenser water level to rise; the process of unit load reduction is the opposite, making full use of the energy storage in the steam turbine heating system, increasing the steam extraction volume during the unit load reduction process, and reducing the steam extraction volume when the load is increased;

[0033] During the operation of the unit, the high-pressure control valve of the steam turbine is fully opened or maintains a large opening, and the throttling loss of the high-pressure control valve is reduced to a minimum; under the premise of ensuring the safe operation of the unit, the control gate that controls the deaerator liquid level responds to the changes in the unit's primary frequency regulation load command.

[0034] Preferably, the condensate intelligent control system architecture includes two parts: a deaerator level control loop and a main steam pressure setting loop of the condensate system;

[0035] The condensate intelligent control system is based on the original three-impulse water level control of the deaerator. It allows the deaerator liquid level to change autonomously within the allowed range instead of maintaining it at a constant value. During the control process, the condensate volume and deaerator liquid level change rapidly. The fluctuation range of the deaerator liquid level is guaranteed to be within the allowed control range through the logic speed limit and amplitude limit of the background condensate variable load instruction.

[0036] The energy-saving control system based on the condensate intelligent control system and deep sliding pressure includes the deaerator level control loop and the main steam pressure setting loop of the condensate system. The newly added energy-saving control system based on the condensate intelligent control system and deep sliding pressure adds three control targets: output main steam pressure setting, deaerator level setting and condensate pump variable frequency feedforward.

[0037] Deaerator liquid level setting loop: The control target of the condensate system is to actively change the condensate flow rate during the load change process, causing the change of the low-pressure heat absorption, changing the low-pressure steam extraction volume, and realizing the increase or decrease of the unit load. This intelligent regulation and change is achieved through the correction of the deaerator liquid level setting. After the variable frequency sliding pressure energy-saving optimization system is put into operation, the original manually set deaerator liquid level setting signal is superimposed on the deaerator liquid level setting signal generated by the optimization system. The condensate volume control feedforward signal needs to be added to the DCS logic. This signal is effective when the variable frequency sliding pressure energy-saving optimization system is put into operation. The load command deviation is directly fed forward to the condensate pump control loop after a series of links judgment, which speeds up the action response speed of the active frequency conversion of the condensate pump.

[0038] Main steam pressure setting loop: After the variable frequency sliding pressure energy-saving optimization system is put into operation, the main steam pressure setting signal will be automatically optimized to reduce the throttling of the regulating valve to achieve the goal of energy-saving operation, while ensuring that the output does not affect the stability of the original coordination loop. In addition, the system also needs to set a limit on the control deviation, that is, within the automatic output range, ensure that the deviation between the output of the main steam pressure setting and the actual main steam pressure signal feedback output of the unit is within a certain range, so as to avoid a large change in the coal input caused by excessive deviation of the main steam pressure.

[0039] Optimally, the system is switched on and off: when the automatic sliding pressure optimization control is put into operation, the main steam pressure setting is automatically corrected based on the original sliding pressure operation curve according to the unit operation status and environmental parameters, and energy-saving and optimized operation is achieved;

[0040] Through optimization measures, the safe operation of the steam turbine high-pressure regulating valve in full-open mode is ensured, the steam turbine regulating valve control logic is retained, and the start and stop buttons are added to the interface. After selecting the "full-open mode", in order to reduce the pressure setting to DEH, the DCS system slowly superimposes a negative offset on the original pressure setting value sent to DEH at a set rate, so that the steam turbine high-pressure regulating valve can operate in full-open sliding pressure; after exiting the full-open mode, it operates according to the original sliding pressure curve, and the negative offset is restored to zero at a set rate, restoring the throttling state of the steam turbine high-pressure regulating valve;

[0041] Automatic exit conditions for turbine valve full-open mode:

[0042] Condition 1: The feedwater pump RB automatically exits the full-open operation mode, the negative bias quickly returns to zero at the set rate, and the high-pressure regulating valve enters the throttling state to maintain the main steam pressure stable and avoid a sharp drop in the main steam temperature;

[0043] Condition 2: The steam turbine trips or dumps the load, automatically exits the full-open operation mode, prepares for the next start-up and grid connection of the unit, and restores the negative bias, so that the main steam pressure and bypass set value are consistent;

[0044] When the condensate intelligent control system is put into automatic control, the system automatically adjusts the deaerator liquid level setting bias and condensate pump feedforward control within a safe range according to the large disturbance primary frequency modulation and AGC instructions, and intelligently controls the condensate flow, increases or decreases the low-pressure heater and deaerator extraction steam, changes the work of the low-pressure cylinder, and assists the unit load increase or decrease.

[0045] Preferably, the control loop input permission rules are:

[0046] (1) Rules for the commissioning of the control loop of the condensate intelligent control system

[0047] Set the prerequisites for allowing the system to be put into operation. When these conditions are not met, the condensate intelligent control system will not be put into operation, or the original operation status will be automatically converted to the exit status. The entry permission rules include: 1) Coordinate CCS to be put into operation automatically; 2) The load is higher than 300MW; 3) The control output instruction of the condensate intelligent control system is not a bad point; 4) The deaerator liquid level control is automatic; 5) The condensate flow meets the requirements and automatically switches to the three-impulse control mode; 6) 5 and 6# low-pressure bypass is closed; 7) 5 and 6# low-pressure inlet and outlet doors are opened; 8) The control mode of the condensate intelligent control system is put into operation; 9) The configuration logic lock of the condensate intelligent control system control is in the allowed state; 10) When the load is greater than 300MW but less than 400MW, due to the pressure limit of the condensate mother pipe, the condensate intelligent control system can be put into operation, but it has no effect;

[0048] The variable load control loop can only be put into operation when all the above-mentioned entry permission rules are met. If one of the conditions is not met, it cannot be put into operation or it will automatically exit to the original automatic control state without disturbance when in operation. In addition, before the condensate water intelligent control system is put into operation, the current deaerator liquid level control target is manually adjusted to 2100mm and then put into operation after stabilization, so as to ensure the safety threshold of the condensate water system intelligent control.

[0049] (2) Automatic Sliding Pressure Optimization Control Loop Entry Permit Rules

[0050] Set the prerequisites for allowing input. When these conditions are not met, the automatic sliding pressure optimization control loop will not be put into operation, or the original operation state will be automatically converted to the exit state. The input permission rules include: 1) The load is higher than 300MW; 2) The coordinated CCS is automatically put into operation; 3) The quality of the real-time automatic sliding pressure optimization control output command is normal; 4) The sliding pressure operation mode is put into operation; 5) The boiler master control is automatic; 6) The automatic sliding pressure optimization control is put into operation; 7) The automatic sliding pressure optimization control input configuration logic lock is in the allowed state;

[0051] The optimization control loop can be put into operation only when all the above-mentioned entry permission rules are met. If one of the conditions is not met, it cannot be put into operation or it will automatically exit to the original automatic control state without disturbance when in the entry state.

[0052] Preferably, the intelligent control logic of the condensate control system is modified as follows:

[0053] (1) High-pressure valve adjustment optimization: Based on the high-pressure valve adjustment optimization model, the optimization control target of the main steam pressure is calculated in real time, and the correction output of the optimal pressure and valve position control target is obtained under the conditions of ambient temperature and heating steam extraction conditions;

[0054] (2) Load response capability bias: Set the corresponding bias curve to avoid the assessment risk of power grid assessment indicators;

[0055] (3) Optimization of primary frequency regulation control system: When the condensate intelligent regulation system is not put into use, or the condensate intelligent regulation system cannot function normally due to excessive water level deviation or other reasons, a larger main steam pressure optimization bias is set to ensure the primary frequency regulation and AGC response capabilities of the unit and avoid grid assessment;

[0056] (4) Correction in case of large control deviation: When there is a large deviation between the control target of the main steam pressure and the actual main steam pressure, the protection logic of large control deviation of the main steam pressure is set. In the case of large control deviation, the main steam pressure correction target is actively corrected to improve the stability of the dynamic process system;

[0057] (5) Condensate intelligent control system: Through the intelligent control of the condensate system, the condensate flow rate is dynamically changed during the process of load increase or decrease, thereby assisting the unit load increase or decrease and improving the unit's primary frequency regulation and AGC response capabilities.

[0058] Preferably, the intelligent control logic of the condensate control system is modified as follows:

[0059] (6) Optimization of deaerator liquid level automatic control: A primary frequency modulation frequency deviation load feedforward is superimposed on the original control loop to quickly respond to the unit load command; when the condenser water level and deaerator liquid level are within the normal range, the unit is loaded and the deaerator liquid level main regulating valve is quickly closed, the condensate flow rate decreases, the low-pressure exhaust volume decreases, and the unit load increases; after the primary frequency modulation cycle ends, the deaerator water level regulating valve gradually returns to the regulated water level state; when the unit load command decreases, the deaerator liquid level regulating valve is quickly opened, the condensate flow rate increases, the steam extraction volume increases, thereby reducing the unit load, and after the primary frequency modulation cycle ends, the deaerator liquid level regulating valve gradually returns to the controlled water level state; if the condenser water level and deaerator liquid level exceed the limit, the condensate system optimization regulation function is stopped and the condenser and deaerator liquid levels are regulated to ensure safe and stable operation of the unit;

[0060] In addition, the condensate flow and condensate pressure are also set with protection interlock limit values ​​to limit the valve opening to keep the condensate flow within a reasonable range, avoiding the interlock start of the condensate pump standby pump, the opening of the condenser recirculation door, or even the tripping of the condensate pump;

[0061] (7) Dynamic recovery of deaerator liquid level: When the unit has been repeatedly reduced or increased in load, the deviation of the deaerator liquid level may continue to increase or decrease and approach the control safety boundary of the deaerator liquid level. In the control range of the non-condensable water intelligent control system, a very small flow rate offset is used to slowly compensate for the water level deviation generated by the previous condensable water intelligent control system.

[0062] (8) Condensate pump control feedforward: The condensate pump variable frequency control feedforward is used to improve the response speed of the condensate system and the load response capability of the condensate pump;

[0063] (9) Optimization of low-pressure boiler water level control: Use the condensate flow rate as the feedforward of the normal drain valve control of the low-pressure boiler, finely adjust the automatic control parameters of the normal drain valve of the low-pressure boiler, and increase the automatic control input function link of the emergency drain valve to avoid unnecessary opening; at the same time, adjust the low-pressure boiler interlock protection constant to ensure that the low-pressure boiler water level operates relatively smoothly when the condensate flow rate fluctuates greatly and frequently, and avoid emergency drain opening and low-pressure boiler protection action, which will affect the safe and stable operation of the unit.

[0064] Preferably, the intelligent control logic of the condensate control system is modified E: the relevant parameters of the DEH control part need to be further optimized and adjusted due to the change of the sliding pressure curve to meet the needs of machine-boiler matching; the impact on the low-pressure saver and the heater is determined through debugging tests; the deaerator liquid level three-impulse control system needs to perform large disturbance control; the optimized frequency conversion command is applied through the deaerator liquid level given bias, the deaerator liquid level control loop needs to be frequently regulated over a large range, and its controller parameters need to be finely optimized and adjusted; the condensate jellyfish pipe low pressure protection constant needs to be reduced to meet the needs of regulation.

[0065] Compared with the prior art, the innovations and advantages of this application are:

[0066] (1) This application uses condensate throttling to intervene in the auxiliary control of primary frequency regulation, and combines it with real-time correction of the optimal sliding pressure operation curve, adopts a preliminary optimization strategy for primary frequency regulation control, and establishes a primary frequency regulation method that incorporates condensate intelligent control. By designing the system's switching and control loop input permission rules, the condensate intelligent control system architecture is improved, the intelligent control logic of the condensate control system is optimized, and the rapid control performance of the unit power is improved. This solves the problem that there is a lag in the steam production process of the coal-fired unit. When the power demand of the power grid changes, the unit cannot quickly respond to power changes by increasing or decreasing the amount of fuel and water supply through the coordinated control system, thereby improving the unit's large disturbance primary frequency regulation performance and AGC response quality. It meets the current increasing power grid capacity, the increasing capacity of the single generator unit, and the increasing requirements of users for power quality, improves the stability of the power grid frequency as an important indicator of power quality, and improves the primary frequency regulation response speed of the generator unit, which is conducive to maintaining the stability of the power grid frequency and meeting the primary frequency regulation assessment requirements of the power grid.

[0067] (2) This application is aimed at 600MW supercritical units, analyzes the characteristics of supercritical boiler units, establishes a solution for condensate intelligent control to assist in improving load response speed, constructs control strategies and optimization solutions, establishes a model for the influence of condensate intelligent control system on load parameters, analyzes the corresponding change relationship between the flow change of condensate system and unit load, deaerator liquid level, condenser water level, and low-heating water level operating parameters, and realizes the application of unit condensate system auxiliary rapid optimization control. It can be fully applied to supercritical unit control systems. The relationship between condensate flow and unit load, deaerator liquid level, etc. is clear. For supercritical unit load rapid control, it solves the problems such as large fluctuations in deaerator and condenser water levels, resulting in instability of some operating conditions and parameters of the unit, and short control effect cycle. Condensate control has some problems in improving the load response speed of the unit primary frequency regulation. When it is actually applied to the unit primary frequency regulation, condensate throttling avoids a large impact on parameters such as deaerator liquid level and condenser water level, and can ensure the safety of unit operation.

[0068] (3) The improved control strategy of the present application is to actively adjust the condensate flow rate to change the low-pressure steam extraction volume, so that the unit can solve the early response of the primary frequency regulation load when the fuel response is delayed, quickly respond to the primary frequency regulation and peak regulation requirements of the power grid, and instantly increase the unit output; at the same time, combined with the optimization of the sliding pressure operation curve, the high-pressure control valve is fully opened or maintained at a large opening during the operation of the turbine, and the throttling loss of the high-pressure control valve is reduced to a minimum; based on the condensate intelligent control system and the energy-saving control architecture of deep sliding pressure, the optimal sliding pressure operation curve is corrected in real time according to the environment and parameter changes, and the condensate intelligent control system model is adopted to improve the rapid control capability of the unit power. The unit power primary frequency regulation effect is good, and it can timely and accurately diagnose and handle power grid power supply frequency faults, and provide early warning to eliminate potential faults. It is of great value to improving the safety and stability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a schematic diagram of the frequency modulation valve position control circuit on the DEH side in the low load section.

[0070] Figure 2 It is a schematic diagram of the fast response circuit of frequency modulation on the DEH side.

[0071] Figure 3 It is a schematic diagram of the circuit formation of the main frequency regulation control command of the steam turbine on the CCS side.

[0072] Figure 4 It is a schematic diagram of a thermal system in which condensate water participates in primary frequency modulation.

[0073] Figure 5 It is a newly added DCS control logic principle schematic diagram.

[0074] Figure 6 It is a curve showing the actual valve opening status of the unit.

[0075] Figure 7 This is a curve chart of the high-pressure shed efficiency and main steam pressure changing with the high-pressure regulating valve opening under the 510MW test condition.

[0076] Figure 8 This is a curve chart of the high-pressure cylinder efficiency and main steam pressure changing with the opening of the high-pressure regulating valve under the 340MW test condition.

[0077] Fig. 9 It is a summary chart of the condensate active regulation system capability test results.

[0078] Fig.10 It is a detailed schematic diagram of the control loop limits.

[0079] Fig.11 It is a schematic diagram of active regulation capability after protection limitation. DETAILED DESCRIPTION

[0080] Below, in conjunction with the accompanying drawings, the technical solution of the improved control method of intelligent primary frequency regulation of thermal power energy storage condensate provided in the present application is further described so that technicians in the field can better understand the present application and implement it.

[0081] The operation and control of ultra-supercritical units are becoming more mature, and the coordinated control system of the units can meet the basic control needs. However, the characteristics of complex control objects and insufficient heat storage of direct current boilers are still prominent, especially with the promotion and implementation of the "two detailed rules" in various regional power grids, which require units to strictly meet the requirements of AGC, primary frequency regulation and other indicators. Coordinated control and traditional primary frequency regulation schemes cannot meet the requirements. This requires continuous optimization of the control system and full and comprehensive exploration of the potential of the units, and the increase of auxiliary equipment and facilities such as energy storage technology to improve the response rate of the unit load.

[0082] This application establishes a solution for intelligent condensate control to assist in improving load response speed, introduces condensate throttling technology into the control system of supercritical thermal power units, modifies control strategies, and optimizes control parameters;

[0083] (1) Analyze the characteristics of supercritical boiler units and establish a solution to assist in improving load response speed by intelligent condensate control;

[0084] (2) Construct an intelligent condensate control model to analyze the relationship between the flow rate change of the condensate system and the corresponding change relationship between the unit load, deaerator liquid level, condenser water level, and low-pressure water level operating parameters;

[0085] (3) After continuous operation and online inspection, the intelligent control of condensate water is of certain significance for improving the primary frequency regulation performance of the unit, improving the correct action rate and qualified action rate of the primary frequency regulation, and reducing the test power caused by the primary frequency regulation.

[0086] For the rapid load regulation of supercritical units, the application of the auxiliary solution of the condensate intelligent control system is feasible. From the test results, it can be seen that the condensate intelligent control system can assist in meeting the requirements of the power grid for primary frequency regulation, which is of certain significance to improving the load response speed of the unit's primary frequency regulation.

[0087] 1. Preliminary optimization strategy for primary frequency modulation control

[0088] (I) Primary frequency modulation improvement control strategy

[0089] The primary frequency regulation circuit of the unit is designed separately in the DEH system and the CCS system. The primary frequency regulation control mode is DEH+CCS. The deviation between the rated speed of the DEH system and the actual speed of the turbine is calculated and directly output to regulate the speed regulating valve; the CCS synchronously regulates the change of the target load set value. The synchronous action of the two systems ensures the rapidity and accuracy of the primary frequency regulation, so that the unit load response meets the primary frequency regulation requirements of the power grid.

[0090] Although the heat storage of supercritical direct current boilers is low, using the heat storage of this part of the boiler is still the primary method to improve the response speed of the unit's primary frequency regulation. The control part of the primary frequency regulation frequency deviation on the load should directly act on the DEH command feedforward. In addition, make the unit boiler master control respond quickly, improve the response speed of feedwater feedforward and fuel quantity control, and compensate for the lag effect of boiler energy storage. In order to ensure the stability of the main steam pressure, try to smoothly restore the primary frequency regulation frequency deviation feedforward, so that the unit boiler combustion control can increase the output quickly.

[0091] In the DEH system, the speed deviation is directly superimposed on the integrated valve position command loop of the steam turbine after passing through the speed deviation-valve comprehensive opening function and the main steam pressure correction factor, so as to quickly change the speed regulating valve opening and ensure the response speed and response amplitude of the primary frequency modulation.

[0092] The DEH speed deviation signal is introduced into the CCS system, and the speed deviation-unit target load function is superimposed on the unit load command to form a loop. At the same time, the frequency modulation load command is directly connected to the main control loop of the steam turbine without delay, avoiding the back-and-forth effect of the CCS system on the actual DEH system frequency modulation action. Based on the correction of the steam turbine load command due to the large deviation of the main steam pressure, during a frequency modulation action, the large deviation of the locking pressure is corrected for the steam turbine load command.

[0093] The primary frequency regulation action loop and the AGC load command lifting and lowering locking control logic are improved, and a human-machine interface is added. The operating personnel set a speed deviation value according to the grid requirements. When the unit speed deviation is greater than the limit value, if the grid frequency is high, the AGC load command is locked to increase the unit load. If the grid frequency is low, the AGC load command is locked to reduce the unit load.

[0094] (II) Control strategy optimization

[0095] Based on the full process analysis of the primary frequency regulation of thermal power units, the factors affecting the quality of primary frequency regulation are found, the signal acquisition and control strategy of the primary frequency regulation of the unit are optimized, and the parameters are optimized in combination with online adjustment and actual operation to improve the primary frequency regulation effect of the unit and the qualified rate of primary frequency regulation. The optimization plan for the primary frequency regulation control strategy of thermal power units is proposed, including:

[0096] (1) Optimization based on improving the quality and availability of primary frequency modulation signals

[0097] The speed signal is used instead of the frequency signal to improve the accuracy of the system. In addition, a starting enhancement loop is set in the system. When the speed deviation is 2 revolutions, the primary frequency modulation frequency deviation load command is 0MW. When the speed deviation is 2.1 revolutions, the primary frequency modulation frequency deviation load command output is 3MW. The corresponding relationship between the speed difference from 2.1 revolutions to 11 revolutions and the load command is linear, which improves the response speed of the primary frequency modulation.

[0098] (2) Optimization of DEH primary frequency modulation circuit in low load section

[0099] When the unit performs primary frequency regulation on the DEH side alone in the low load section, due to the low pressure in front of the unit, the frequency regulation power amplitude cannot meet the grid requirements under the same frequency regulation valve position opening. Figure 1 ) Increase the valve position correction factor change corresponding to the set main steam pressure of the unit, amplify the frequency modulation valve position instruction, and realize the corresponding frequency difference to the frequency modulation valve position amplitude requirement. Figure 1 It can be seen that the actual speed of the unit generates a reference frequency modulation valve position instruction after passing through the frequency modulation dead zone and the preset speed inequality function. After setting the main steam pressure correction function, it finally generates a pressure-corrected frequency modulation valve position instruction.

[0100] The unit frequency modulation response speed is one of the parameters to judge whether the frequency modulation is qualified. In order to speed up the unit frequency modulation response speed, a pressure correction frequency modulation valve position command feedforward loop is added to the DEH comprehensive valve position command control loop. Figure 2 It can be seen that when the unit is controlled in power closed loop, pressure closed loop or DEH control is in remote control mode, the frequency regulation valve position feedforward instruction is directly used to quickly respond to the grid's requirements for the unit's primary frequency regulation speed.

[0101] Experiments have confirmed that by adding a primary frequency regulation valve position feedforward loop to the valve position control loop on the DEH side, the response speed of the primary frequency regulation load can be improved. By introducing the main steam pressure correction factor in the DEH frequency regulation loop, the amplitude and durability problems of the primary frequency regulation load in the low-load stage of the unit can be solved.

[0102] (3) Solution to the problem of frequency modulation synchronization between CCS side and DEH side

[0103] Due to the insufficient measurement accuracy of the unit frequency transmitter, according to the grid's requirement that the turbine speed signal should be used for frequency modulation signal selection, the control logic of this application uses the turbine speed signal and the rated speed deviation signal as the synchronous CCS side and DEH side frequency modulation action signal. Figure 1 The speed deviation signal is directly introduced into the primary frequency modulation control loop of the coordination control loop. The speed deviation signal is converted into the corresponding primary frequency modulation load instruction through a preset function. After the primary frequency modulation frequency deviation load instruction summarizes the unit load instruction, it is directly sent to the steam turbine main control and boiler main control loops.

[0104] DEH and CCS use the same speed deviation signal to ensure the dynamic synchronization of primary frequency regulation of DEH and CCS. At the same time, the unit responds quickly to the fluctuation of grid frequency deviation and meets the continuity and stability of the positive contribution of primary frequency regulation load when the grid frequency deviation fluctuates with large amplitude and long cycle.

[0105] Improvement of the main control power circuit of the steam turbine on the CCS side: By improving the frequency modulation load instruction and the main steam pressure deviation locking circuit in the main control circuit of the steam turbine on the CCS side, the stability of the unit load response is increased and the pullback effect on the primary frequency modulation action on the DEH side is avoided.

[0106] Avoid the CCS side from pulling back the DEH side frequency control loop when the unit is in the primary frequency regulation action, and improve the CCS side steam turbine main control loop. Figure 3 . Add a direct loop of frequency modulation load command to avoid the pull-back effect of load command on frequency modulation action; because the main steam pressure deviation will increase after the frequency modulation action, thereby weakening the amplitude of the frequency modulation load command action, a special method is added to lock the current main steam pressure deviation control loop after the frequency modulation action occurs, and slowly release the main steam pressure deviation control loop after the frequency modulation action disappears for a period of time (generally 30s) to avoid the disturbance of steam turbine load command due to the main steam pressure fluctuation of the unit, and to meet the power grid's requirements for the durability and stability of frequency modulation load to the greatest extent.

[0107] (4) Other optimization and improvement contents

[0108] 1) The DEH side directly applies the frequency deviation signal to the turbine speed regulating valve command. The DEH primary frequency modulation power component should directly enter the OSB feedforward output, cancel the inertia link, and quickly change the turbine speed regulating valve opening;

[0109] 2) Both sides of the turbine and boiler respond to the primary frequency modulation together. The DEH speed deviation signal is directly introduced into the CCS system. At the same time, the frequency modulation load command is directly passed through the turbine main control and boiler main control loop without delay, which speeds up the rate at which the primary frequency modulation frequency deviation load command is output to the power command, and speeds up the combustion response speed on the boiler side;

[0110] 3) When the primary frequency regulation is in low-frequency operation and the unit is not in the process of load reduction, the main steam pressure deviation loop is locked, or the weight function value in the main steam pressure correction control strategy of the steam turbine is reduced to reduce the reverse regulation on the steam turbine side;

[0111] 4) After the first frequency modulation action, the main steam pressure deviation increases, weakening the frequency modulation load command action amplitude, and after the first frequency modulation action occurs, the current main steam pressure deviation control loop is locked;

[0112] 5) When the primary frequency modulation is in low frequency operation, increase the primary air pressure setting value; use the powder storage system to speed up the boiler combustion response speed;

[0113] 6) During a frequency modulation action, reduce the inertia time of the water supply command control logic.

[0114] 2. Primary frequency modulation method integrating intelligent control of condensate water

[0115] By utilizing the non-traditional control potential of the generator set itself, at the moment when the unit rapidly increases or decreases load, before the boiler output catches up, the unit output is guaranteed to meet the more rapid adjustment needs. The control strategies of thermal power units include: 1) changing the feed water flow (increase for direct current boilers and reduce for drum boilers); 2) increasing the amount of cooling water; 3) throttling the turbine high-pressure steam inlet control valve; 4) turbine bypass; 5) high-pressure heater bypass; 6) extraction throttling; 7) condensate throttling;

[0116] By increasing the boiler master control command at a faster rate, the feed water and fuel amount are quickly increased, the heat storage is replenished in time, and the steam pressure is maintained stable, but the load change lasts for a long time, but the lag is serious; opening the control valve, opening the steam supply control valve, and the water spray method can quickly control the load, but the sustainability is poor; reducing the amount of condensed water can increase the load response speed, but the duration is also relatively limited.

[0117] Due to issues such as safe operation and economic efficiency of the unit, some of the above strategies cannot be applied in practice. Most existing steam turbine generator sets release stored energy through throttling of high-pressure control valves. Since throttling of steam is an irreversible loss, it causes a decrease in the economic efficiency of the unit operation. For steam turbines that adopt throttling control, this decrease is more significant.

[0118] This application adjusts the condensate flow rate to change the low-pressure steam extraction volume, so that the amount of steam entering the turbine to do work changes, so that the unit can quickly increase the output when the boiler fuel response lags, and then respond to the peak load and frequency regulation requirements of the power grid. The schematic diagram of the thermal system in which the condensate system intervenes in primary frequency regulation is shown in the figure. Figure 4 shown.

[0119] When the unit is loaded, the condensate flow rate is reduced, the amount of steam work in the turbine is increased, the low-pressure extraction volume is reduced, the unit load is increased, and the condensate flow rate is reduced, which will cause the deaerator liquid level to drop and the condenser water level to rise; the unit load reduction process is the opposite, making full use of the energy storage in the steam turbine heating system, increasing the steam extraction volume during unit load reduction and reducing the steam extraction volume when the unit is loaded. Overall, the load change has no impact on the economy, there is no throttling, and there is no energy loss.

[0120] During the operation of the unit, the high-pressure control valve of the steam turbine is fully opened or maintains a large opening, and the throttling loss of the high-pressure control valve is reduced to a minimum.

[0121] Under the premise of ensuring the safe operation of the unit, let the control gate that controls the deaerator liquid level (or the frequency of the condensate pump inverter) respond to the change of the unit's primary frequency regulation load instruction;

[0122] Before the condensate intelligent control system strategy is reliably implemented and applied, the multiple systems of the unit are comprehensively optimized and debugged to optimize the control strategy of the deaerator, low-pressure heater, condenser water level, condenser make-up water, and condensate pump minimum flow. It is also necessary to sort out, adjust, and debug the protection constants of these control objects.

[0123] 3. Condensate intelligent control system architecture

[0124] The condensate intelligent control system intervenes in the primary frequency modulation control, which includes two parts: the deaerator level control loop and the main steam pressure setting loop of the condensate system;

[0125] The condensate intelligent control system is based on the original three-impulse water level control of the deaerator. It allows the deaerator liquid level to change autonomously within the allowed range instead of maintaining it at a constant value. During the control process, the condensate volume and the deaerator liquid level change rapidly. The fluctuation range of the deaerator liquid level is ensured to be within the allowed control range through the logic speed limit and amplitude limit of the background condensate variable load instruction (the normal range is 2150-2450mm, which may be set and modified in the logic, and there may be a small dynamic control overshoot);

[0126] The condensate intelligent control system may also have a certain impact on the condenser and each low-pressure heater water level. However, compared with the original automatic control system that feeds forward to add or subtract condensate when raising or lowering the load, it produces a certain degree of neutralization. In theory, the disturbance is smaller, but it cannot rule out the possibility that the above-mentioned water level deviates from the normal range due to reasons such as the drain water level or the original control loop of the condenser water level. The condensate variable load control is equipped with corresponding lifting and lowering locks, and attention must be paid to changes in the water levels of each low-pressure heater, deaerator and condenser.

[0127] The energy-saving control system based on the condensate intelligent regulation system and deep sliding pressure includes the deaerator liquid level control loop and the main steam pressure setting loop of the condensate system. The newly added energy-saving control system based on the condensate intelligent regulation system and deep sliding pressure adds three control targets: output main steam pressure setting, deaerator liquid level setting and condensate pump frequency feedforward.

[0128] Deaerator liquid level setting loop: The control target of the condensate system is to actively change the condensate flow rate during the load change process, causing the change of the low-pressure heat absorption, changing the low-pressure steam extraction volume, and realizing the increase or decrease of the unit load. This intelligent regulation and change is achieved through the correction of the deaerator liquid level setting. After the variable frequency sliding pressure energy-saving optimization system is put into operation, the original manually set deaerator liquid level setting signal is superimposed on the deaerator liquid level setting signal generated by the optimization system. The condensate volume control feedforward signal needs to be added to the DCS logic. This signal is effective when the variable frequency sliding pressure energy-saving optimization system is put into operation. The load command deviation is directly fed forward to the condensate pump control loop after a series of links judgment, which speeds up the action response speed of the active frequency conversion of the condensate pump.

[0129] Main steam pressure setting loop: After the variable frequency sliding pressure energy-saving optimization system is put into operation, the main steam pressure setting signal will be automatically optimized to reduce the throttling of the regulating valve to achieve the goal of energy-saving operation, while ensuring that the output does not affect the stability of the original coordination loop. In addition, the system also needs to set a limit on the control deviation, that is, to ensure that the deviation between the output of the main steam pressure setting and the actual main steam pressure signal feedback output of the unit is within a certain range within the automatic output range, so as to avoid a large change in the coal input caused by excessive deviation of the main steam pressure, which in turn causes difficulties in the dynamic process control of the main steam and reheat steam temperatures.

[0130] (I) System switching

[0131] The system includes two parts: condensate intelligent control system control and automatic sliding pressure optimization control, involving the deaerator level control circuit and the main steam pressure setting circuit of the condensate system. The switching operation is carried out in the unit coordination interface. The switching buttons of the two control circuits are set in the lower left corner of the unit coordination interface. When the input conditions are met, click the input button to input the corresponding circuit. Otherwise, click the exit button to exit the corresponding circuit.

[0132] The condensate water intelligent control system and the real-time sliding pressure optimization loop can be switched on and off separately. When successfully switched on, the red "switch-on" mark will be displayed, and the water level setting bias of the condensate water intelligent control system and the optimized bias value of the real-time sliding pressure that have been switched on will be displayed above the switch-on button. At the same time, the switch-on mark and water level setting bias of the condensate water intelligent control system loop will be displayed on the "condensate water system" interface at the same time.

[0133] When the automatic sliding pressure optimization control is put into operation, the main steam pressure setting is automatically corrected based on the original sliding pressure operation curve according to the unit operation status and environmental parameters, and energy-saving and optimized operation is achieved;

[0134] Through optimization measures, the safe operation of the steam turbine high-pressure regulating valve in full-open mode is ensured, the steam turbine regulating valve control logic is retained, and the start and stop buttons are added to the interface. After selecting the "full-open mode", in order to reduce the pressure setting to DEH, the DCS system slowly superimposes a negative offset on the original pressure setting value sent to DEH at a set rate, so that the steam turbine high-pressure regulating valve can operate in full-open sliding pressure; after exiting the full-open mode, it operates according to the original sliding pressure curve, and the negative offset is restored to zero at a set rate, restoring the throttling state of the steam turbine high-pressure regulating valve;

[0135] Automatic exit conditions for turbine valve full-open mode:

[0136] Condition 1: The feedwater pump RB automatically exits the full-open operation mode, the negative bias quickly returns to zero at the set rate, and the high-pressure regulating valve enters the throttling state to maintain the main steam pressure stable and avoid a sharp drop in the main steam temperature;

[0137] Condition 2: The steam turbine trips or dumps the load, automatically exits the full-open operation mode, prepares for the next start-up and grid connection of the unit, and restores the negative bias, so that the main steam pressure and bypass set value are consistent;

[0138] When the condensate intelligent control system is put into automatic control, the system automatically adjusts the deaerator liquid level setting bias and condensate pump feedforward control within a safe range according to the large disturbance primary frequency modulation and AGC instructions, and intelligently controls the condensate flow, increases or decreases the low-pressure heater and deaerator extraction steam, changes the work of the low-pressure cylinder, and assists the unit load increase or decrease.

[0139] (II) Rules for the input permission of control circuits

[0140] (1) Rules for the commissioning of the control loop of the condensate intelligent control system

[0141] Set the prerequisites for allowing the system to be put into operation. When these conditions are not met, the condensate intelligent control system will not be put into operation, or the original operation status will be automatically converted to the exit status. The entry permission rules include: 1) Coordinate CCS to be put into operation automatically; 2) The load is higher than 300MW; 3) The control output instruction of the condensate intelligent control system is not a bad point; 4) The deaerator liquid level control is automatic; 5) The condensate flow meets the requirements and automatically switches to the three-impulse control mode; 6) 5 and 6# low-pressure bypass is closed; 7) 5 and 6# low-pressure inlet and outlet doors are opened; 8) The control mode of the condensate intelligent control system is put into operation; 9) The configuration logic lock of the condensate intelligent control system control is in the allowed state; 10) When the load is greater than 300MW but less than 400MW, due to the pressure limit of the condensate mother pipe, the condensate intelligent control system can be put into operation, but it has no effect;

[0142] The variable load control loop can be put into operation only when all the above-mentioned entry permission rules are met. If one of the conditions is not met, it cannot be put into operation or it will automatically exit to the original automatic control state without disturbance when in operation. In addition, before the condensate water intelligent control system is put into operation, the current deaerator liquid level control target is manually adjusted to 2100mm and stabilized before the condensate water system intelligent control loop is put into operation to ensure the safety threshold of the condensate water system intelligent control.

[0143] (2) Automatic Sliding Pressure Optimization Control Loop Entry Permit Rules

[0144] Set the prerequisites for allowing input. When these conditions are not met, the automatic sliding pressure optimization control loop will not be put into operation, or the original operation state will be automatically converted to the exit state. The input permission rules include: 1) the load is higher than 300MW; 2) the coordinated CCS is automatically put into operation; 3) the quality of the real-time automatic sliding pressure optimization control output command is normal; 4) the sliding pressure operation mode (VP mode) is put into operation; 5) the boiler master control is automatic; 6) the automatic sliding pressure optimization control is put into operation; 7) the automatic sliding pressure optimization control input configuration logic lock is in the allowed state;

[0145] The optimization control loop can be put into operation only when all the above-mentioned entry permission rules are met. If one of the conditions is not met, it cannot be put into operation or it will automatically exit to the original automatic control state without disturbance when in the entry state.

[0146] 4. Intelligent control logic of condensate control system

[0147] Added DCS control logic and some logic principle diagrams as follows Figure 5 shown.

[0148] Figure 5 In the modification of control logic, the original main steam pressure setting logic and condensate system logic will be modified as follows, and the corresponding control logic loop will be added:

[0149] (1) High-voltage valve optimization

[0150] Based on the high-pressure regulating valve optimization model, the optimization control target of the given main steam pressure is calculated in real time, and the correction output of the optimal pressure and valve position control target is obtained under the conditions of ambient temperature and heating steam extraction conditions;

[0151] (2) Load response capability bias

[0152] When operating according to the optimal sliding pressure and valve position control targets, the load response capability may be weakened under low load conditions, which may result in the primary frequency regulation and AGC corresponding capabilities being subject to grid assessment. Even when the condensate intelligent control system is in effect, the above problems may exist in some load sections. Therefore, it is necessary to set a corresponding bias curve to avoid the assessment risk of grid assessment indicators.

[0153] (3) Primary frequency modulation control system optimization

[0154] When the condensate intelligent control system is not put into use, or the condensate intelligent control system cannot function normally due to excessive water level deviation or other reasons, the load response capability of the system will decrease. At this time, a larger main steam pressure optimization bias is set to ensure the primary frequency regulation and AGC response capability of the unit and avoid the assessment of the power grid;

[0155] (4) Correction for large control deviation

[0156] When there is a large deviation between the control target of the main steam pressure and the actual main steam pressure, a large boiler control command is generated through the coordination system, which may cause a large fluctuation in the output of the fuel main control loop, thereby affecting the coordinated control stability of the unit and causing dynamic problems such as over-temperature and over-pressure. Therefore, a protection logic with large main steam pressure control deviation is set. When the control deviation is large, the main steam pressure correction target is actively corrected to improve the stability of the dynamic process system.

[0157] (5) Condensate intelligent control system

[0158] Through the intelligent regulation of the condensate system, the condensate flow rate is dynamically changed during the process of load increase or decrease, thereby assisting the unit in load increase or decrease and improving the response capability of the unit's primary frequency regulation and AGC.

[0159] (6) Optimization of automatic control of deaerator liquid level

[0160] The deaerator liquid level is controlled by the deaerator water level regulating valve or the condensate pump frequency conversion control. The optimization strategy is: a primary frequency modulation frequency deviation load feedforward is superimposed on the original control loop to quickly respond to the unit load command; when the condenser water level and deaerator liquid level are within the normal range, the unit is loaded, and the deaerator liquid level main regulating valve is quickly closed (or the condensate pump frequency conversion frequency is reduced), the condensate flow rate decreases, the low-pressure exhaust volume decreases, and the unit load increases; after the primary frequency modulation cycle ends, the deaerator water level regulating valve gradually returns to the water level control state; when the unit load command decreases, the deaerator liquid level regulating valve is quickly opened (or the condensate pump frequency conversion frequency is increased), the condensate flow rate increases, the steam extraction volume increases, thereby reducing the unit load, and after the primary frequency modulation cycle ends, the deaerator liquid level regulating valve gradually returns to the water level control state;

[0161] If the condenser water level and deaerator liquid level exceed the limit, the condensate system optimization control function will be stopped and the condenser and deaerator liquid levels will be regulated to ensure safe and stable operation of the unit;

[0162] In addition, the condensate flow and condensate pressure are also set with protection interlock limit values ​​to limit the valve opening (condensate pump frequency conversion frequency) to ensure that the condensate flow is within a reasonable range, avoiding the interlock start of the condensate pump standby pump, the opening of the condenser recirculation door, or even the tripping of the condensate pump;

[0163] (7) Dynamic recovery of deaerator liquid level

[0164] The control process of the condensate intelligent control system will affect the control of the deaerator liquid level. When the unit reduces or increases the load for multiple times in succession, the deviation of the deaerator liquid level may continue to increase or decrease and approach the control safety boundary of the deaerator liquid level, causing the capacity of the condensate intelligent control system to be weakened or even disappear. Therefore, it is necessary to use a very small flow offset to slowly compensate for the water level deviation generated by the previous condensate intelligent control system in the non-condensate intelligent control system control range;

[0165] (8) Condensate pump control feedforward

[0166] The output of the main controller of the condensate water intelligent control system is the deaerator liquid level control bias. On the one hand, the instruction transmission process is long and the effect is relatively slow; on the other hand, when the load instruction changes, the load control deviation will cause the rapid action of the valve, thereby limiting the output of the condensate water intelligent control system. Therefore, the response speed of the condensate water system is improved through the condensate pump variable frequency control feedforward, and the condensate pump variable load response capability is improved.

[0167] (9) Low water level control optimization

[0168] Before the implementation of the condensate intelligent control system optimization plan, the condensate flow parameters were relatively stable during normal operation of the unit. Similarly, the fluctuation of the low water level was small and would not change frequently and rapidly.

[0169] However, after the implementation of the condensate intelligent control system optimization plan, the condensate flow rate will change frequently, rapidly and significantly. If no measures are taken to optimize and adjust the low-pressure heater water level control, the following problems will occur: When the condensate flow rate increases rapidly, the low-pressure heater steam extraction volume increases, the low-pressure heater water level rises, and the low-pressure heater normal drain is not adjusted in time, which will cause the emergency drain valve to open, affecting the efficiency of the heat recovery system; when the condensate flow rate decreases rapidly, the low-pressure heater steam extraction volume decreases, and the low-pressure heater water level drops. If the low-pressure heater normal drain is not adjusted in time, the low-pressure heater water level will be too low, triggering the closure of the steam extraction valve, threatening the safe and stable operation of the unit. Therefore, it is necessary to optimize and debug the control logic of the low-pressure heater normal drain and emergency drain valve;

[0170] Optimization plan: Use the condensate flow rate as the feedforward of the normal drain valve control of the low-pressure heater, finely adjust the automatic control parameters of the normal drain valve of the low-pressure heater, and increase the automatic control input function link of the emergency drain valve to avoid unnecessary opening; at the same time, adjust the low-pressure heater interlock protection constant to ensure that the low-pressure heater water level runs relatively smoothly when the condensate flow rate fluctuates greatly and frequently, and avoid emergency drain opening and low-pressure heater protection action, which will affect the safe and stable operation of the unit.

[0171] (10) Other optimizations

[0172] Some relevant parameters of DEH control need to be further optimized and adjusted due to the change of sliding pressure curve to meet the needs of turbine-boiler matching; since the relevant control has a certain impact on the operation of the low-voltage combined heater system, the relevant debugging process should be gradual, and the impact on the low-voltage and heater should be determined through debugging tests; the deaerator liquid level three-impulse control system needs to be regulated for large disturbances; the optimized frequency conversion command is applied through the deaerator liquid level given bias, and the deaerator liquid level control loop needs to be frequently regulated over a large range, and its controller parameters need to be finely optimized and adjusted; the condensate jellyfish pipe low pressure protection constant needs to be reduced to meet the needs of regulation.

[0173] 5. Application model of condensate water intelligent control system

[0174] (I) Sliding pressure curve optimization

[0175] Partial load sliding pressure operation of thermal power units can reduce high-pressure valve throttling and achieve better economic operation. The fixed-sliding-fixed operation mode has become a more commonly used operation mode for actual units. However, the conventional fixed curve method of calculating the sliding pressure operation target based on electric power ignores the impact of changes in the environment and operating conditions, resulting in changes in the unit's variable load capacity and economy under different conditions. Actual operating units often have a certain potential for optimization of variable load capacity and economy.

[0176] The actual operating main steam pressure and actual regulating valve opening of the test unit under different loads are as follows: Figure 6 shown.

[0177] from Figure 6 It can be seen that the actual main steam pressure of the unit basically follows a sliding pressure curve, and under this sliding pressure curve, the actual unit's valve opening presents a band distribution. This is due to the temperature difference between winter and summer and between day and night, which causes the actual unit's back pressure to change, and ultimately leads to the same main steam pressure and load. The unit requires different valve openings to achieve the required flow. Therefore, the average valve opening is larger in summer when the temperature is high, and the average valve opening is smaller in winter.

[0178] Taking the 500MW load point as an example, the flow characteristic curve test of the unit high-speed regulating valve was carried out. The lower limit regulating valve opening of the strip distribution is about 29%, and the upper limit regulating valve opening of the strip distribution is about 36%, which affects the optimal main steam pressure deviation by about 1.9MPa. The corresponding load changes of unit opening are 2.07% and 0.97% respectively, and the load increase potential is 15% and 8% respectively. The difference between the two is nearly 100%, so the corresponding primary frequency regulation and AGC response capabilities are also quite different.

[0179] (II) Valve tuning characteristics test

[0180] The high-pressure cylinder efficiency and main steam pressure were tested under different load conditions as the high-pressure regulating valve opening changed.

[0181] from Figure 7 The data shows that when the unit is running at 510MW load, as the main steam pressure decreases, the high-pressure cylinder efficiency has a clear upward trend, and the increase is greater than that of the 600MW load condition; the valve opening is about 55%, the high-pressure cylinder efficiency is close to 87.5%, and the main steam pressure is about 22MPa. The point where the high-pressure cylinder thermal efficiency is the lowest, the main steam pressure is about 19MPa. In the 510MW test condition, the change range of the high-pressure cylinder efficiency at high load is larger and more obvious than that of the 600MW load condition.

[0182] from Figure 8The data shows that when the unit is running at a load of 340MW, as the main steam pressure decreases, the efficiency of the high-pressure cylinder has a clear upward trend. When the valve opening is about 60%, the efficiency of the high-pressure cylinder is close to 87.5%, and the main steam pressure is about 13.8MPa. At the point where the thermal efficiency of the high-pressure cylinder is the lowest, the main steam pressure is about 12.5MPa.

[0183] The efficiency of the high-pressure cylinder does not change significantly at high load, but increases significantly at low load. This corresponds to the valve adjustment and steam distribution method before and after the unit optimization. This optimization is reflected in the improvement of efficiency at low load.

[0184] According to the above results, the flow characteristic curve of the test unit's regulating valve is obtained. The linear area of ​​the regulating valve control is approximately within 30%, and the upper inflection point is around 39%. This shows that when the unit's regulating valve opening reaches more than 39%, the unit's regulation performance will decline significantly. At this time, the primary frequency regulation and AGC performance of the power grid will face greater challenges. On the other hand, it also shows that when the unit's regulating valve opening is approximately below 35%, the unit has obvious throttling losses and has great energy-saving potential.

[0185] (III) Test on the response load capacity of the condensate intelligent control system

[0186] The condensate intelligent control system capacity characteristic tests were carried out under 600MW load conditions. The tests tested the variable load response characteristics under different load conditions, and the test data were collected during the test.

[0187] During the test, coordination, AGC and primary frequency regulation were maintained in normal operation. During the test, the deaerator water level fluctuated between 1970-2250mm and did not exceed the above limits. During the test, the test plan and abnormal handling plan were formulated to ensure the safe and stable operation of the unit, and the monitoring of system parameters was strengthened. When the deaerator water level fluctuated violently and exceeded the range of 1900-2300mm, or any low-pressure heater or condenser water level alarm was triggered, the test process was exited to maintain system stability.

[0188] (1) Manual slow reduction of 100t / h under 600MW condition: Under the full load 600MW operating condition of the test unit, by closing the condensate valve opening, reducing the condensate pump frequency conversion or lowering the condenser water level setting value, the condensate flow rate is slowly reduced by 100t / h, and the condensate flow rate is reduced from 1260t / h to 1120t / h. The maximum load of the unit can be increased by about 10MW. Under this condition, the deaerator water level drops from 2120mm to 2030mm, a decrease of 90mm. The condenser water level rises from 720mm to 860mm, an increase of 140mm. The No. 6 low-pressure water level fluctuates between -3mm and +8mm.

[0189] (2) 600MW manual rapid reduction of 100t / h: Under the full load 600MW operating condition of the test unit, the condensate flow rate was rapidly reduced by 100t / h, and the condensate flow rate dropped from 1260t / h to 1100t / h. The maximum load of the unit could be increased by about 9MW. Under this condition, the deaerator water level dropped from 2060mm to 1880mm, a decrease of 180mm. The condenser water level rose from 830mm to 970mm, an increase of 140mm. The No. 6 low-pressure water level fluctuated between -8mm and +14mm.

[0190] (3) 600MW manual rapid reduction of 300t / h: Under the full load 600MW operating condition of the test unit, the condensate flow rate was manually and rapidly reduced by 300t / h, and the condensate flow rate dropped from 1300t / h to 1000t / h. The maximum load of the unit could be increased by about 10MW. Under this condition, the deaerator water level dropped from 2150mm to 2050mm, a decrease of 200mm. The condenser water level rose from 750mm to 890mm, an increase of 140mm. The No. 6 low-pressure water level fluctuated between -25mm and +15mm.

[0191] (4) 600MW manual rapid reduction of 600t / h: Under the full load 600MW operating condition of the test unit, the condensate flow rate was manually and rapidly reduced by 600t / h, and the condensate flow rate dropped from 1400t / h to 700t / h. The maximum load of the unit could be increased by about 17MW. Under this condition, the deaerator water level dropped from 2170mm to 1870mm, a decrease of 300mm. The condenser water level rose from 770mm to 1030mm, an increase of 260mm. The No. 6 low-pressure water level fluctuated between -30mm and +28mm.

[0192] (5) 600MW frequency conversion quickly reduces 300t / h: Under the full load 600MW operating condition of the test unit, the frequency conversion quickly reduces the condensate flow by 300t / h, and the condensate flow drops from 1300t / h to 900t / h. The maximum load of the unit can be increased by about 11MW. Under this condition, the deaerator water level drops from 2100mm to 1920mm, a decrease of 180mm. The condenser water level rises from 770mm to 950mm, an increase of 180mm. The No. 6 low-pressure water level fluctuates between -33mm and +20mm.

[0193] (6) 600MW frequency conversion quickly reduces 600t / h: When the test unit is operating at full load of 600MW, without combining other control measures, only the condensate intelligent control system is used, that is, by closing the condensate regulating valve opening, reducing the condensate pump frequency conversion frequency or lowering the condenser water level setting value, the condensate flow rate is quickly reduced by 600t / h. The condensate flow rate is reduced from 1370t / h to 750th, and the unit load can be increased by about 17MW at most.

[0194] Under the 600MW test conditions, the condensate flow rate dropped from 1370t / h to 750t / h, and the deaerator water level dropped from 2120mm to 1870mm, a decrease of 250mm. The condenser water level rose from 730mm to 990mm, an increase of 260mm. The No. 6 low-pressure water level rose from -33mm to +30mm, an increase of 63mm.

[0195] (IV) Analysis of the test results of the condensate intelligent control system capability

[0196] From the test results Fig. 9 It can be seen that the maximum flow change reaches 676t / h, the load change is 13.873MW, the load response contribution is 2.31%, and the average load response time is about 10s. From the fitting results, it can be seen that the unit load change of every 100t / h condensate flow change is equivalent to about 1900kW, which is equivalent to the variable load capacity of similar units. According to the upper limit of the unit condensate flow change of 500t / h, the actual variable load capacity of the auxiliary unit can be about 9.6MW, which is equivalent to 1.6% of the rated load. The condensate intelligent control system has great potential for improving the power response of the unit's primary frequency regulation.

[0197] The test results of the condensate intelligent control system capability are analyzed as follows:

[0198] (1) The condensate flow rate change assisting primary frequency regulation has little impact on the unit's operating economy;

[0199] (2) Intelligent control of condensate flow has a reverse effect on unit load changes, that is, reducing the condensate flow will significantly increase the unit load; and the greater the flow control, the greater the load change, and the faster the unit load change rate;

[0200] (3) Controlling the condensate flow rate by the deaerator liquid level regulating valve can respond to load changes more quickly than controlling the condensate flow rate by changing the condensate pump frequency conversion, but the condensate system will also produce certain throttling losses;

[0201] (4) The condensate intelligent control system can effectively improve the load response speed by utilizing the turbine side energy storage, but it also causes large fluctuations in the water level of the deaerator, low-pressure heater, and condenser, which has a negative impact on the stability of unit parameters and safe operation;

[0202] Condensate intelligent control system solution, changing the condensate flow rate will cause a large fluctuation in the deaerator liquid level. Therefore, controlling the deaerator water level within a reasonable range is a necessary prerequisite for the practical application of this solution. Reducing the fluctuation range of the deaerator liquid level can make this solution more practical. The solutions of this application include:

[0203] 1) Carefully debug the deaerator control valve and condensate pump frequency conversion automatic control to improve the response speed of the deaerator liquid level three-impulse automatic control to ensure the control quality;

[0204] 2) While closing the liquid level regulating valve, open the condensate feed water pump to the deaerator feed water gate to feed water to the deaerator, reduce the deaerator liquid level fluctuation, and avoid the feed water pump tripping;

[0205] 3) Modify the low-pressure heating system, add a low-pressure heating bypass to the deaerator, and install a regulating valve on the bypass. While closing the opening of the regulating valve on the low-pressure heating side, increasing the opening of the bypass regulating valve can reduce the water level of the deaerator, and in theory, the optimized regulation effect is more lasting. When reducing the flow rate, you should also pay attention to the safety of the low-pressure heating operation;

[0206] 4) When the deaerator liquid level is high, it is necessary to connect the deaerator to the condenser overflow valve.

[0207] (V) Control logic parameter settings and protection limits

[0208] 1. Control logic protection limitation

[0209] In order to achieve disturbance-free switching and protect the safety and stability of the system, the system circuit adopts a series of restrictions. The details and values ​​are as follows Fig.10 The above restrictions keep the action speed and amplitude of the condensate intelligent control system within a safe range and will not have a significant impact on the operation of the unit.

[0210] 2. Test of system control capability after protection limit

[0211] To ensure the safety and stability of each system of the unit, the condensate intelligent control system was actually put into operation. The three-impulse feedforward effect of condensate was first weakened. The feedforward effect was reduced by 22%, which is equivalent to reducing the condensate flow rate by 22% when the unit is loaded. Calculated based on the 12MW load increase, the feedwater flow rate increased dynamically by about 40t / h, and the condensate flow rate feedforward decreased by 8.8t / h, corresponding to a quantitative load capacity of 167kW. Secondly, the absolute value of condensate flow control was limited to within ±200t / h.

[0212] After setting the protection limit, according to the test results under different load conditions of the unit, it is concluded that the condensate intelligent control system can achieve the upper limit of auxiliary variable load capacity as follows: Fig.11 shown.

Claims

1. An improved control method for intelligent primary frequency regulation of thermal power energy storage condensate, characterized in that: Through the auxiliary control of primary frequency regulation by intervening condensate throttling, combined with real-time correction of the optimal sliding pressure operation curve, the preliminary optimization strategy of primary frequency regulation control is adopted, and a primary frequency regulation method integrating condensate intelligent regulation is established. By designing the system switching and control loop input permission rules, the condensate intelligent regulation system architecture is improved, the intelligent control logic of the condensate regulation system is optimized, the rapid regulation performance of the unit power is improved, and the unit large disturbance primary frequency regulation performance and AGC response quality are improved; The improved control strategy is to actively adjust the condensate flow rate to change the low-pressure steam extraction volume, so that the unit can solve the early response of the primary frequency regulation load when the fuel response is delayed, quickly respond to the primary frequency regulation and peak regulation requirements of the power grid, and instantly increase the unit output; at the same time, combined with the optimization of the sliding pressure operation curve, the high-pressure control valve is fully opened or maintained at a large opening during the operation of the turbine, and the throttling loss of the high-pressure control valve is minimized; based on the energy-saving control architecture of the condensate intelligent control system and deep sliding pressure, the optimal sliding pressure operation curve is corrected in real time according to the environment and parameter changes, and the condensate intelligent control system model is adopted to improve the rapid control capability of the unit power; This application targets 600MW supercritical units, analyzes the characteristics of supercritical boiler units, establishes a solution for intelligent condensate control to assist in improving load response speed, builds control strategies and optimization solutions, establishes a model for the influence of the intelligent condensate control system on load parameters, analyzes the flow changes of the condensate control system, and the corresponding changes between the unit load, deaerator liquid level, condenser water level, and low-pressure water level operating parameters, to achieve the unit condensate system auxiliary rapid optimization control application.

2. According to claim 1, the method for improving the intelligent primary frequency modulation of thermal power energy storage condensate is characterized in that: Primary frequency modulation control preliminary optimization strategy A: 1) Optimization based on improving the quality and availability of primary frequency modulation signals: the speed signal is used instead of the frequency signal to improve the accuracy of the system; in addition, a starting enhancement loop is set in the system. When the speed deviation is 2 revolutions, the primary frequency modulation frequency deviation load command is 0MW. When the speed deviation is 2.1 revolutions, the primary frequency modulation frequency deviation load command output is 3MW. The corresponding relationship between the speed difference from 2.1 revolutions to 11 revolutions and the load command is linear, which improves the response speed of the primary frequency modulation; 2) Optimization of DEH primary frequency modulation circuit in low load section: By increasing the valve position correction factor change corresponding to the set main steam pressure of the unit in the control logic, the frequency modulation valve position instruction is amplified to achieve the corresponding frequency difference for the frequency modulation valve position amplitude requirement. The actual speed of the unit generates a reference frequency modulation valve position instruction after passing through the frequency modulation dead zone and the preset speed inequality function. After setting the main steam pressure correction function, the pressure-corrected frequency modulation valve position instruction is finally generated. A pressure-corrected frequency-regulating valve position command feedforward loop is added to the DEH integrated valve position command control loop. When the unit is controlled in power closed loop, pressure closed loop or DEH is controlled in remote control mode, the frequency-regulating valve position feedforward command is used to quickly respond to the grid's requirements for the unit's primary frequency regulation speed. 3) Solution to the problem of synchronization of frequency modulation action between CCS side and DEH side: The control logic uses the turbine speed signal and the rated speed deviation signal as the synchronization signal of frequency modulation action between CCS side and DEH side. The speed deviation signal is directly introduced into the primary frequency modulation control loop of the coordination control loop. The speed deviation signal is converted into the corresponding primary frequency modulation load instruction through a preset function. The primary frequency modulation frequency deviation load instruction summarizes the unit load instruction and directly goes to the turbine master control and boiler master control loops. DEH and CCS use the same speed deviation signal to ensure the synchronization of primary frequency regulation between DEH and CCS. At the same time, the unit responds quickly to the fluctuation of grid frequency deviation and meets the continuity and stability of positive contribution of primary frequency regulation load when the grid frequency deviation fluctuates with large amplitude and long cycle. Improvement of the main control power circuit of the steam turbine on the CCS side: By improving the frequency modulation load instruction and the main steam pressure deviation locking circuit in the main control circuit of the steam turbine on the CCS side, the stability of the unit load response is increased and the pullback effect on the primary frequency modulation action on the DEH side is avoided; Avoid the CCS side from pulling back the frequency regulation control loop on the DEH side when the unit performs a frequency regulation action, improve the main control loop of the steam turbine on the CCS side, add a direct loop of the frequency regulation load command, and avoid the load command pulling back the frequency regulation action; add a lock on the current main steam pressure deviation control loop after a frequency regulation action occurs, and slowly release the main steam pressure deviation control loop after the frequency regulation action disappears for a period of time, so as to avoid the disturbance of the steam turbine load command due to the main steam pressure fluctuation of the unit, and maximize the satisfaction of the power grid's requirements for the durability and stability of the frequency regulation load.

3. According to claim 1, the method for improving the intelligent primary frequency modulation of thermal power energy storage condensate is characterized in that: Primary frequency modulation control preliminary optimization strategy B: 1) The DEH side directly applies the frequency deviation signal to the turbine speed regulating valve command. The DEH primary frequency modulation power component should directly enter the OSB feedforward output, cancel the inertia link, and quickly change the turbine speed regulating valve opening; 2) Both sides of the turbine and boiler respond to the primary frequency modulation together. The DEH speed deviation signal is directly introduced into the CCS system. At the same time, the frequency modulation load command is directly passed through the turbine main control and boiler main control loop without delay, which speeds up the rate at which the primary frequency modulation frequency deviation load command is output to the power command, and speeds up the combustion response speed on the boiler side; 3) When the primary frequency regulation is in low-frequency operation and the unit is not in the process of load reduction, the main steam pressure deviation loop is locked, or the weight function value in the main steam pressure correction control strategy of the steam turbine is reduced to reduce the reverse regulation on the steam turbine side; 4) After the frequency modulation action, the main steam pressure deviation increases, weakening the frequency modulation load command action amplitude, and after the frequency modulation action occurs, the current main steam pressure deviation control loop is locked; 5) When the primary frequency modulation is in low frequency operation, increase the primary air pressure setting value; use the powder storage system to speed up the boiler combustion response speed; 6) During a frequency modulation action, reduce the inertia time of the water supply command control logic.

4. According to claim 1, the method for improving the intelligent primary frequency modulation of thermal power energy storage condensate is characterized in that: Primary frequency regulation method integrating intelligent condensate control: by adjusting the condensate flow rate to change the low-pressure steam extraction volume, the amount of steam entering the steam turbine to do work changes, so that the unit can quickly increase its output when the boiler fuel response lags, thereby responding to the peak load and frequency regulation requirements of the power grid; When the unit is loaded, the condensate flow rate is reduced, the amount of steam work in the turbine is increased, the low-pressure steam extraction volume is reduced, the unit load is increased, and the condensate flow rate is reduced, which will cause the deaerator liquid level to drop and the condenser water level to rise; the process of unit load reduction is the opposite, making full use of the energy storage in the steam turbine heating system, increasing the steam extraction volume during the unit load reduction process, and reducing the steam extraction volume when the load is increased; During the operation of the unit, the high-pressure control valve of the steam turbine is fully opened or maintains a large opening, and the throttling loss of the high-pressure control valve is reduced to a minimum; under the premise of ensuring the safe operation of the unit, the control gate that controls the deaerator liquid level responds to the changes in the unit's primary frequency regulation load command.

5. According to claim 1, the method for improving the intelligent primary frequency regulation of thermal power energy storage condensate is characterized in that: Condensate intelligent control system architecture: includes two parts: the deaerator level control loop and the main steam pressure setting loop of the condensate system; The condensate intelligent control system is based on the original three-impulse water level control of the deaerator. It allows the deaerator liquid level to change autonomously within the allowed range instead of maintaining it at a constant value. During the control process, the condensate volume and deaerator liquid level change rapidly. The fluctuation range of the deaerator liquid level is guaranteed to be within the allowed control range through the logic speed limit and amplitude limit of the background condensate variable load instruction. The energy-saving control system based on the condensate intelligent control system and deep sliding pressure includes the deaerator level control loop and the main steam pressure setting loop of the condensate system. The newly added energy-saving control system based on the condensate intelligent control system and deep sliding pressure adds three control targets: output main steam pressure setting, deaerator level setting and condensate pump variable frequency feedforward. Deaerator liquid level setting loop: The control target of the condensate system is to actively change the condensate flow rate during the load change process, causing the change of the low-pressure heat absorption, changing the low-pressure steam extraction volume, and realizing the increase or decrease of the unit load. This intelligent regulation and change is achieved through the correction of the deaerator liquid level setting. After the variable frequency sliding pressure energy-saving optimization system is put into operation, the original manually set deaerator liquid level setting signal is superimposed on the deaerator liquid level setting signal generated by the optimization system. The condensate volume control feedforward signal needs to be added to the DCS logic. This signal is effective when the variable frequency sliding pressure energy-saving optimization system is put into operation. The load command deviation is directly fed forward to the condensate pump control loop after a series of links judgment, which speeds up the action response speed of the active frequency conversion of the condensate pump. Main steam pressure setting loop: After the variable frequency sliding pressure energy-saving optimization system is put into operation, the main steam pressure setting signal will be automatically optimized to reduce the throttling of the regulating valve to achieve the goal of energy-saving operation, while ensuring that the output does not affect the stability of the original coordination loop. In addition, the system also needs to set a limit on the control deviation, that is, within the automatic output range, ensure that the deviation between the output of the main steam pressure setting and the actual main steam pressure signal feedback output of the unit is within a certain range, so as to avoid a large change in the coal input caused by excessive deviation of the main steam pressure.

6. According to claim 1, the method for improving the intelligent primary frequency regulation of thermal power energy storage condensate is characterized in that: System switching: When the automatic sliding pressure optimization control is put into operation, the main steam pressure setting is automatically corrected based on the original sliding pressure operation curve according to the unit operation status and environmental parameters, and energy-saving and optimized operation is achieved; Through optimization measures, the safe operation of the steam turbine high-pressure regulating valve in full-open mode is ensured, the steam turbine regulating valve control logic is retained, and the start and stop buttons are added to the interface. After selecting the "full-open mode", in order to reduce the pressure setting to DEH, the DCS system slowly superimposes a negative offset on the original pressure setting value sent to DEH at a set rate, so that the steam turbine high-pressure regulating valve operates in full-open sliding pressure; after exiting the full-open mode, it operates according to the original sliding pressure curve, and the negative offset is restored to zero at a set rate, restoring the throttling state of the steam turbine high-pressure regulating valve; Automatic exit conditions for turbine valve full-open mode: Condition 1: The feedwater pump RB automatically exits the full-open operation mode, the negative bias quickly returns to zero at the set rate, and the high-pressure regulating valve enters the throttling state to maintain the main steam pressure stable and avoid a sharp drop in the main steam temperature; Condition 2: The steam turbine trips or dumps the load, automatically exits the full-open operation mode, prepares for the next start-up and grid connection of the unit, and restores the negative bias, so that the main steam pressure and bypass set value are consistent; When the condensate intelligent control system is put into automatic control, the system automatically adjusts the deaerator liquid level setting bias and condensate pump feedforward control within a safe range according to the large disturbance primary frequency modulation and AGC instructions, and intelligently controls the condensate flow, increases or decreases the low-pressure heater and deaerator extraction steam, changes the work of the low-pressure cylinder, and assists the unit load increase or decrease.

7. According to claim 1, the method for improving the intelligent primary frequency regulation of thermal power energy storage condensate is characterized in that: Control loop input permission rules: (1) Rules for the commissioning of the control loop of the condensate intelligent control system Set the prerequisites for allowing the system to be put into operation. When these conditions are not met, the condensate intelligent control system will not be put into operation, or the original operation status will be automatically converted to the exit status. The entry permission rules include: 1) Coordinate CCS to be put into operation automatically; 2) The load is higher than 300MW; 3) The control output instruction of the condensate intelligent control system is not a bad point; 4) The deaerator liquid level control is automatic; 5) The condensate flow meets the requirements and automatically switches to the three-impulse control mode; 6) 5 and 6# low-pressure bypass is closed; 7) 5 and 6# low-pressure inlet and outlet doors are opened; 8) The control mode of the condensate intelligent control system is put into operation; 9) The configuration logic lock of the condensate intelligent control system control is in the allowed state; 10) When the load is greater than 300MW but less than 400MW, due to the pressure limit of the condensate mother pipe, the condensate intelligent control system can be put into operation, but it has no effect; The variable load control loop can only be put into operation when all the above-mentioned entry permission rules are met. If one of the conditions is not met, it cannot be put into operation or it will automatically exit to the original automatic control state without disturbance when in operation. In addition, before the condensate water intelligent control system is put into operation, the current deaerator liquid level control target is manually adjusted to 2100mm and then put into operation after stabilization, so as to ensure the safety threshold of the condensate water system intelligent control. (2) Automatic Sliding Pressure Optimization Control Loop Entry Permit Rules Set the prerequisites for allowing input. When these conditions are not met, the automatic sliding pressure optimization control loop will not be put into operation, or the original operation state will be automatically converted to the exit state. The input permission rules include: 1) The load is higher than 300MW; 2) The coordinated CCS is automatically put into operation; 3) The quality of the real-time automatic sliding pressure optimization control output command is normal; 4) The sliding pressure operation mode is put into operation; 5) The boiler master control is automatic; 6) The automatic sliding pressure optimization control is put into operation; 7) The automatic sliding pressure optimization control input configuration logic lock is in the allowed state; The optimization control loop can be put into operation only when all the above-mentioned entry permission rules are met. If one of the conditions is not met, it cannot be put into operation or it will automatically exit to the original automatic control state without disturbance when in the entry state.

8. According to claim 1, the method for improving the intelligent primary frequency regulation of thermal power energy storage condensate is characterized in that: Condensate control system intelligent control logic modification C: (1) High-pressure valve adjustment optimization: Based on the high-pressure valve adjustment optimization model, the optimization control target of the main steam pressure is calculated in real time, and the correction output of the optimal pressure and valve position control target is obtained under the conditions of ambient temperature and heating steam extraction conditions; (2) Load response capability bias: Set the corresponding bias curve to avoid the assessment risk of power grid assessment indicators; (3) Optimization of primary frequency regulation control system: When the condensate intelligent regulation system is not put into use, or the condensate intelligent regulation system cannot function normally due to excessive water level deviation or other reasons, a larger main steam pressure optimization bias is set to ensure the primary frequency regulation and AGC response capabilities of the unit and avoid grid assessment; (4) Correction in case of large control deviation: When there is a large deviation between the control target of the main steam pressure and the actual main steam pressure, the protection logic of large control deviation of the main steam pressure is set. In the case of large control deviation, the main steam pressure correction target is actively corrected to improve the stability of the dynamic process system; (5) Condensate intelligent control system: Through the intelligent control of the condensate system, the condensate flow rate is dynamically changed during the process of load increase or decrease, thereby assisting the unit load increase or decrease and improving the unit's primary frequency regulation and AGC response capabilities.

9. The method for improving the intelligent primary frequency regulation of thermal power energy storage condensate according to claim 1 is characterized in that: Condensate control system intelligent control logic modification D: (6) Optimization of deaerator liquid level automatic control: A primary frequency modulation frequency deviation load feedforward is superimposed on the original control loop to quickly respond to the unit load command; when the condenser water level and deaerator liquid level are within the normal range, the unit is loaded and the deaerator liquid level main regulating valve is quickly closed, the condensate flow rate decreases, the low-pressure exhaust volume decreases, and the unit load increases; after the primary frequency modulation cycle ends, the deaerator water level regulating valve gradually returns to the regulated water level state; when the unit load command decreases, the deaerator liquid level regulating valve is quickly opened, the condensate flow rate increases, the steam extraction volume increases, thereby reducing the unit load, and after the primary frequency modulation cycle ends, the deaerator liquid level regulating valve gradually returns to the controlled water level state; if the condenser water level and deaerator liquid level exceed the limit, the condensate system optimization regulation function is stopped and the condenser and deaerator liquid levels are regulated to ensure safe and stable operation of the unit; In addition, the condensate flow and condensate pressure are also set with protection interlock limit values ​​to limit the valve opening to keep the condensate flow within a reasonable range, avoiding the interlock start of the condensate pump standby pump, the opening of the condenser recirculation door, or even the tripping of the condensate pump; (7) Dynamic recovery of deaerator liquid level: When the unit has been repeatedly reduced or increased in load, the deviation of the deaerator liquid level may continue to increase or decrease and approach the control safety boundary of the deaerator liquid level. In the control range of the non-condensable water intelligent control system, a very small flow rate offset is used to slowly compensate for the water level deviation generated by the previous condensable water intelligent control system. (8) Condensate pump control feedforward: The condensate pump variable frequency control feedforward is used to improve the response speed of the condensate system and the load response capability of the condensate pump; (9) Optimization of low-pressure boiler water level control: Use the condensate flow rate as the feedforward of the normal drain valve control of the low-pressure boiler, finely adjust the automatic control parameters of the normal drain valve of the low-pressure boiler, and increase the automatic control input function link of the emergency drain valve to avoid unnecessary opening; at the same time, adjust the low-pressure boiler interlock protection constant to ensure that the low-pressure boiler water level operates relatively smoothly when the condensate flow rate fluctuates greatly and frequently, and avoid emergency drain opening and low-pressure boiler protection action, which will affect the safe and stable operation of the unit.

10. The method for improving the intelligent primary frequency regulation of thermal power energy storage condensate according to claim 1 is characterized in that: Modification E of the intelligent control logic of the condensate control system: Some relevant parameters of the DEH control need to be further optimized and adjusted due to the changes in the sliding pressure curve to meet the needs of boiler matching; the impact on the low-pressure saver and heater is determined through debugging tests; the deaerator liquid level three-impulse control system needs to be regulated for large disturbances; the optimized frequency conversion command is applied through the deaerator liquid level given bias, and the deaerator liquid level control loop needs to be frequently regulated over a large range, and its controller parameters need to be finely optimized and adjusted; the condensate jellyfish pipe low pressure protection constant needs to be reduced to meet the needs of regulation.

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