A method and system for controlling a thermal power generating unit in a boiler-turbine mode

Abstract

The application provides a kind of machine follows furnace mode thermal power generating unit control method and system, belong to thermal power generating unit control technical field, the method includes: according to first control action signal and second control action signal, control heating control device to control the electric heating power of electric boiler;According to first steam pressure difference signal and pressure difference adjusting signal, determine second steam pressure difference signal, to control the opening of turbine admission regulating valve;According to first opening signal and second opening signal, control the opening of feedwater pump feedwater regulating valve.The machine follows furnace mode thermal power generating unit control method and system provided by the application increase steam pressure anti-interference control link, turbine nonlinear limiting control link, feedwater feedforward control link and electric boiler proportional differential control link, ultimately reach the coordinated control target of giving consideration to load power tracking performance, electric boiler liquid level and steam pressure fluctuation, feedwater control and electric power control response speed three aspects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal power unit control, and in particular to a thermal power unit control method and system in a mode of turbine following boiler. BACKGROUND

[0002] At present, the thermal power unit device mostly adopts a control mode of "turbine following boiler" or "boiler following turbine", and basically adopts a mode of relatively independent operation of the boiler and the steam turbine generator, without realizing coordinated control of the boiler and the steam turbine generator, and thus unable to meet the basic requirement of "quickly adapting to load power variation and keeping the boiler liquid level and steam pressure within the allowable range", and there are problems of poor load power tracking performance, large fluctuation of the boiler liquid level and the steam pressure, and long dynamic response process time. SUMMARY

[0003] The present application provides a thermal power unit control method and system in a mode of turbine following boiler, to solve the defects of poor load power tracking performance, large fluctuation of the boiler liquid level and the steam pressure, and long dynamic response process time in the prior art.

[0004] In a first aspect, the present application provides a thermal power unit control method in a mode of turbine following boiler, comprising: controlling a heating control device to control the electric heating power of an electric boiler according to a first control action signal and a second control action signal; wherein the first control action signal is generated according to the sum of a steam pressure disturbance compensation signal and a power difference signal, and the second control action signal is generated according to the load power signal of the steam turbine by using a proportional and differential strategy; wherein the steam pressure disturbance compensation signal is determined according to the steam pressure signal, and is used to compensate the variation disturbance of the power difference signal, and the power difference signal is the difference between the load power signal of the steam turbine and the actual power signal.

[0005] determining a second steam pressure difference signal according to the first steam pressure difference signal and a pressure difference adjustment signal, to control the opening degree of the admission regulating valve of the steam turbine; wherein the first steam pressure difference signal is the difference between the steam pressure preset signal and the steam pressure signal, and the pressure adjustment signal is the output signal when the power difference signal is used as the input signal of the two-way amplitude limiting proportional amplifier;

[0006] controlling the opening degree of the feedwater regulating valve of the feedwater pump according to a first opening degree signal and a second opening degree signal; the first opening degree signal is determined according to the electric boiler liquid level difference signal, the feedwater flow signal and the steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

[0007] According to the thermal power unit control method in the mode of turbine following boiler provided by the present application, the steam pressure disturbance compensation signal is determined according to the steam pressure signal, to compensate the variation disturbance of the power difference signal, which comprises:

[0008] A first-order inertial differential control strategy is adopted to generate a steam pressure disturbance compensation signal according to a steam pressure signal; the relationship of the first-order inertial differential control strategy is as follows:

[0009]

[0010] wherein T d is an inertial time constant, K d is a proportional gain constant, and s is a Laplace operator; and the expression of the steam pressure disturbance compensation signal is as follows:

[0011]

[0012] wherein p T is the steam pressure signal;

[0013] The inertial time constant and the proportional gain constant are set so that the sum of the steam pressure disturbance compensation signal and a power difference signal is 0.

[0014] According to the method, the step of generating the pressure regulating signal by using the two-way limiting amplifier proportioner comprises: inputting the power difference signal as an input signal into the two-way limiting amplifier proportioner; when the power difference signal is in the limiting area of the two-way limiting amplifier proportioner, the pressure regulating signal linearly changes in positive correlation with the change of the power difference signal; and when the power difference signal is in the horizontal saturation area on both sides of the two-way limiting amplifier proportioner, the pressure regulating signal remains the current pressure regulating signal with the change of the power difference signal.

[0015] According to the method, the first opening degree signal is determined according to an electric boiler liquid level difference signal, a feed water flow signal and a steam flow signal, and the method comprises: determining an expected feed water flow signal for compensating the liquid level fluctuation of the electric boiler according to the electric boiler liquid level difference signal; determining the first opening degree signal according to the expected feed water flow signal, the feed water flow signal and the steam flow signal to realize the supply of the expected feed water flow; and determining the second opening degree signal according to a second steam pressure difference signal, and the method comprises: determining the second opening degree signal according to the second steam pressure difference signal by using a proportional integral strategy.

[0016] According to the method, the method further comprises: determining a rotation speed signal of the feed water pump according to a differential pressure error of the feed water regulating valve, and adjusting the rotation speed of the feed water pump so that the differential pressure error is less than a preset threshold value; and the differential pressure error is the difference between a differential pressure set value and a differential pressure measured value of the feed water regulating valve.

[0017] According to the method, the heating control device is a thyristor or a contactor.

[0018] In a second aspect, the present application further provides a control system for a thermal power unit in a turbine-following- boiler mode, comprising:

[0019] a first control module configured to control the heating control device to control the electric heating power of the electric boiler according to a first control action signal and a second control action signal, wherein the first control action signal is generated according to a sum of a steam pressure disturbance compensation signal and a power difference signal, and the second control action signal is generated according to a load power signal of the steam turbine by using a proportional-derivative strategy, wherein the steam pressure disturbance compensation signal is determined according to a steam pressure signal and is used to compensate for the variation disturbance of the power difference signal, and the power difference signal is the difference between the load power signal of the steam turbine and an actual power signal;

[0020] a second control module configured to determine a second steam pressure difference signal according to a first steam pressure difference signal and a pressure difference adjustment signal, so as to control the opening degree of the admission regulating valve of the steam turbine, wherein the first steam pressure difference signal is the difference between a steam pressure preset signal and a steam pressure signal, and the pressure adjustment signal is the output signal when the power difference signal is used as the input signal of a two-way amplitude limiting proportional amplifier;

[0021] a third control module configured to control the opening degree of the feedwater regulating valve of the feedwater pump according to a first opening degree signal and a second opening degree signal, wherein the first opening degree signal is determined according to an electric boiler liquid level difference signal, a feedwater flow signal and a steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

[0022] According to the control system for the thermal power unit in the turbine-following-boiler mode, the system further comprises a fourth control module.

[0023] The fourth control module is configured to determine a rotation speed signal of the feedwater pump according to a differential pressure error of the feedwater regulating valve, and adjust the rotation speed of the feedwater pump so that the differential pressure error is less than a preset threshold value.

[0024] The differential pressure error is the difference between a differential pressure set value and a differential pressure actual value of the feedwater regulating valve.

[0025] In a third aspect, the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the control method for the thermal power unit in the turbine-following-boiler mode as described above.

[0026] In a fourth aspect, the present application further provides a non-transitory computer readable storage medium, which stores a computer program, wherein the computer program is executable on a processor to implement the steps of the control method for the thermal power unit in the turbine-following-boiler mode as described above.

[0027] The application provides a method and system for controlling a thermal power unit in a turbine-following-boiler mode, which adds a steam pressure anti-disturbance control link, a turbine nonlinear limiting control link, a feedwater feedforward control link and an electric boiler proportional differential control link, so as to finally achieve a coordinated control target of considering load power tracking performance, electric boiler liquid level and steam pressure fluctuation, feedwater control and electric power control response speed. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0029] Figure 1 Fig. 1 is a schematic diagram of a principle framework of a method for controlling a thermal power unit in a turbine-following-boiler mode provided by the application;

[0030] Figure 2 Fig. 2 is a schematic diagram of a control principle of electric power of an electric boiler provided by the application;

[0031] Figure 3 Fig. 3 is a schematic diagram of a principle of a nonlinear control link provided by the application;

[0032] Figure 4 Fig. 4 is a schematic diagram of a three-impulse cascade-feedforward composite control method of a feedwater controller provided by the application;

[0033] Figure 5 Fig. 5 is a schematic diagram of a structure of an electronic device provided by the application. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the application clearer, the following will combine the drawings in the application to clearly and completely describe the technical solutions in the application. Obviously, the described embodiments are some of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the application.

[0035] It should be noted that in the description of the embodiments of the present application, the terms "comprising", "containing" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or further includes elements inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or apparatus including the element.

[0036] The terms "first", "second", and the like in the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally a class, and do not limit the number of objects, for example, the first object can be one or more. In addition, "and / or" means at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in a "or" relationship.

[0037] In order to more clearly describe the technical solutions of the present application, before the specific introduction of the technical solutions of the present application, the practical application scene and the technical demand analysis process of the present application are further described below.

[0038] With the development of electric power industry, the proportion of high parameter and large capacity thermal power generating units in power grid is increasing, and the load peak-valley difference of power grid gradually increases due to the change of power consumption structure, so it is required that large thermal power generating units have the ability to run with variable load, so as to quickly meet the needs of dynamic change of load power, and the steam pressure will not trigger the action of safety protection system due to exceeding the set limit value.

[0039] In addition, as the capacity of the thermal power unit is continuously increasing, the heat storage capacity of the boiler is relatively reduced, and the boiler and the steam turbine generator need to jointly ensure the external load power tracking requirement and jointly maintain the stability of the internal operating parameters (mainly the steam pressure and the boiler liquid level). In the boiler and steam turbine generator control system of the thermal power unit device, whether the actual output power of the steam turbine generator is consistent with the load power reflects the energy supply and demand balance relationship between the steam turbine generator and the external load; whether the boiler liquid level and the steam pressure are stable reflects the energy supply and demand balance relationship between the boiler and the steam turbine generator. The dynamic characteristics of the boiler and the steam turbine generator are quite different: the steam turbine generator responds quickly to the load power, while the boiler responds slowly to the load power due to the large thermal inertia. Therefore, the two energy supply and demand balance relationships inside and outside the thermal power unit device are mutually restricted, and there is an irreconcilable contradiction between the fast response characteristic of the external load power and the stability of the internal operating parameters.

[0040] According to the dynamic characteristics of the boiler and the steam turbine generator of the thermal power unit device during the rapid variable working condition process, from the change of the boiler heating power, the compensation of the liquid level fluctuation of the boiler by the action of the feed water pump / feed water regulating valve, to the change of the output power of the steam turbine generator caused by the action of the steam turbine inlet regulating valve, the whole process has a large inertia delay. If only relying on the boiler power control and the feed water control, a faster load power response cannot be obtained. Therefore, the control mode of "machine following boiler" or "boiler following machine" is not suitable for the tracking of the external load power, the coordinated control of the boiler-steam turbine generator is not realized, and the basic requirement of "quickly adapting to the load power change and keeping the boiler liquid level and the steam pressure within the allowable range" cannot be met.

[0041] In view of the problems of the "machine following boiler" or "boiler following machine" control mode of the thermal power unit device, such as poor load power tracking performance, large fluctuation of the boiler liquid level and the steam pressure, and long dynamic response process time, the present application provides an improved machine following boiler electric boiler-steam turbine generator coordinated control method and system, that is, a machine following boiler mode thermal power unit control method and system, to improve the comprehensive control performance such as load power tracking performance, steam generator liquid level fluctuation, feed water control and stack power control response speed. The machine following boiler mode thermal power unit control method and system provided by the present application uses an electric boiler instead of a conventional gas-fired boiler, and adjusts the heating current of the heating control device to realize the heating power adjustment of the electric boiler. The specific control method comprises:

[0042] (1) According to the first control action signal and the second control action signal, the heating control device is controlled to control the electric heating power of the electric boiler.

[0043] The first control action signal is generated according to the sum of a steam pressure disturbance compensation signal and a power difference signal; the second control action signal is generated according to a load power signal of the steam turbine by using a proportional differential strategy. The power difference signal is the difference between the load power signal and an actual power signal of the steam turbine.

[0044] Further, the steam pressure disturbance compensation signal is determined according to a steam pressure signal, and is used to compensate for the change disturbance of the power difference signal.

[0045] The heating control device can be a thyristor or a contactor.

[0046] (2) The second steam pressure difference signal is determined according to the first steam pressure difference signal and the pressure difference regulation signal, so as to control the opening degree of the inlet regulating valve of the steam turbine.

[0047] The first steam pressure difference signal is the difference between a steam pressure preset signal and a steam pressure signal, and the pressure regulation signal is the output signal when the power difference signal is used as the input signal of a bidirectional limiting amplifier.

[0048] (3) The opening degree of the feedwater regulating valve of the feedwater pump is controlled according to the first opening degree signal and the second opening degree signal. The first opening degree signal is determined according to an electric boiler liquid level difference signal, a feedwater flow signal and a steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

[0049] The control system corresponding to the control method comprises:

[0050] The first control module is configured to control the heating control device to control the electric heating power of the electric boiler according to the first control action signal and the second control action signal. The first control action signal is generated according to the sum of a steam pressure disturbance compensation signal and a power difference signal, and the second control action signal is generated according to a load power signal of the steam turbine by using a proportional differential strategy. The steam pressure disturbance compensation signal is determined according to a steam pressure signal, and is used to compensate for the change disturbance of the power difference signal. The power difference signal is the difference between the load power signal and an actual power signal of the steam turbine.

[0051] The second control module is configured to determine the second steam pressure difference signal according to the first steam pressure difference signal and the pressure difference regulation signal, so as to control the opening degree of the inlet regulating valve of the steam turbine. The first steam pressure difference signal is the difference between a steam pressure preset signal and a steam pressure signal, and the pressure regulation signal is the output signal when the power difference signal is used as the input signal of a bidirectional limiting amplifier.

[0052] The third control module is used for controlling the opening degree of the feed water regulating valve of the feed water pump according to the first opening degree signal and the second opening degree signal; the first opening degree signal is determined according to the electric boiler liquid level difference signal, the feed water flow signal and the steam flow signal; and the second opening degree signal is determined according to the second steam pressure difference signal.

[0053] The control method and system of the thermal power generating unit in the mode of turbine following boiler are described below. Figures 1-5 The control method and system of the thermal power generating unit in the mode of turbine following boiler are described below.

[0054] Figure 1 The principle framework diagram of the control method of the thermal power generating unit in the mode of turbine following boiler is shown in the figure, Figure 1 The control method provided by the application is used for realizing the coordinated control of the electric boiler-turbine (turbine generator), and the control system includes an electric power controller, a feed water controller, a turbine controller, a non-linear limiting control link, a feed-forward control link, a proportional differential control link, a pressure disturbance control link and a control object.

[0055] It can be known from the analysis that the control method of the thermal power generating unit in the mode of turbine following boiler is formed on the basis of increasing the steam pressure disturbance control link, the turbine non-linear limiting control link, the feed water feed-forward control link and the electric boiler proportional differential control link in the conventional turbine following boiler control mode.

[0056] The electric power controller is the same as the conventional turbine following boiler control mode, and the principle diagram is shown in the figure, Figure 2 Figure 2 The electric power controller receives the power difference signal of the external load power and the actual power of the turbine generator, adopts the PID control or model prediction control strategy, calculates the control action signal of the thyristor / contactor on line, adjusts the electric heating power output, and makes the heating power of the electric boiler follow the change of the external load power.

[0057] The steam pressure disturbance control link is used for determining the steam pressure disturbance compensation signal according to the steam pressure signal, so as to compensate the change disturbance of the power difference signal.

[0058] ​Specifically, the steam pressure disturbance rejection control stage is designed to reduce the impact of turbine inlet regulating valve opening disturbances on the electric boiler power control. It receives the steam pressure signal, employs a first-order inertial differential control strategy, and outputs the steam pressure disturbance rejection control signal (i.e., the steam pressure disturbance compensation signal) and the power difference signal. After processing by an adder, these are input to the electric boiler power controller. The relationship of the first-order inertial differential control strategy is as follows:

[0059]

[0060] Among them, T d K is the inertial time constant. d Let be the proportional gain constant, and s be the Laplace operator.

[0061] The control function of the steam pressure disturbance rejection control link can be described as follows: When the load power requirement remains unchanged, if the opening of the turbine's intake regulating valve changes due to some disturbance, the actual power generated by the turbine generator will change accordingly. This disturbance will generate a power difference signal, which will drive the electric power controller to operate, which is not conducive to the stable operation of the thermal power unit.

[0062] Add a steam pressure disturbance rejection control signal to the input of the power controller:

[0063]

[0064] Where, p T This is a steam pressure signal.

[0065] As long as T in the first-order inertial differential control strategy d K d When the appropriate selection is made, the input to the power controller will be as follows when the turbine intake regulating valve is activated:

[0066]

[0067] Where ΔP is the power difference between the external load power and the actual power generated by the turbine generator, the electric power controller does not need to respond to the opening disturbance of the turbine inlet regulating valve and can compensate for the changes in the actual power generated by the turbine generator. The electric power controller can then generate the first control action signal based on the sum of the steam pressure disturbance compensation signal and the power difference signal.

[0068] The proportional differential control link of the electric boiler is set to compensate the inertia delay of the electric boiler load power response and the influence of the turbine inlet regulating valve opening change on the boiler electric power control system. According to the external load power signal, the second control action signal of the heating control device (thyristor / contactor) is calculated on line through the proportional differential control link. When the external load power changes, the second control action signal of the thyristor / contactor can be sent out through the proportional differential control link, so that the control of the electric boiler power can be advanced and strengthened, and the inertia of the electric boiler load power response characteristic can be improved.

[0069] The first control action signal of the electric power controller output and the second control action signal of the proportional differential control link output are processed by an adder, and then the total control action signal of the thyristor / contactor is output to regulate the electric power output.

[0070] Figure 3 The principle diagram of the nonlinear control link provided by the application is shown in Fig. 1. Figure 3 The nonlinear limiting control link of the turbine reduces the control quality of the steam pressure to further improve the tracking response speed of the load power. The nonlinear limiting control link receives the power difference signal and outputs a pressure difference regulating signal proportional to the power difference, temporarily changes the set value of the steam pressure, i.e. the steam pressure preset signal, so as to fully release the heat storage capacity of the electric boiler to improve the adaptability of the load power.

[0071] Specifically, when the load power increases, the power difference signal is input to the electric power controller to increase the electric heating power output by the thyristor / contactor. At the same time, the set value of the steam pressure is temporarily reduced through the nonlinear limiting control link, the inlet regulating valve opening output by the turbine controller is increased, and the measured power output by the turbogenerator set is rapidly increased. Conversely, when the load power decreases, the set value of the steam pressure is increased through the nonlinear limiting control link, the inlet regulating valve opening output by the turbine controller is decreased, and the measured power output by the turbogenerator set is rapidly decreased.

[0072] The nonlinear limiting control link is realized by a bidirectional limiting amplifier, which includes: inputting the power difference signal as an input signal to the bidirectional limiting amplifier; when the power difference signal is in the limiting area of the bidirectional limiting amplifier, the pressure regulating signal changes linearly in positive correlation with the change of the power difference signal; when the power difference signal is in the horizontal saturation area on both sides of the bidirectional limiting amplifier, the pressure regulating signal remains the current pressure regulating signal regardless of the change of the power difference signal.

[0073] As can be seen, the change of the steam pressure set value is limited within a certain range to prevent the steam pressure fluctuation from deviating from the set value beyond the allowable range.

[0074] Referring to Figure 1 It can be seen that the final signal received by the steam turbine controller is the second steam pressure difference signal, i.e.

[0075] Second steam pressure difference signal = Steam pressure preset signal + (-Steam pressure signal) + (-Pressure difference regulation signal)

[0076] Steam pressure preset signal + (-Steam pressure signal) + (-Pressure difference regulation signal)

[0077] = Steam pressure preset signal - Steam pressure signal - Pressure difference regulation signal

[0078] = First steam pressure difference signal - Pressure difference regulation signal

[0079] The steam turbine controller is the same as the conventional "machine follows furnace" control mode, receives the steam pressure signal, the steam pressure set signal, the pressure difference signal (i.e. the pressure difference regulation signal) output by the non-linear limiting control link, and after processing by the adder, enters the steam turbine controller, adopts the PID control or the advanced control strategy, and calculates the opening degree signal of the inlet regulating valve generated by the steam turbine controller online. The steam pressure is regulated by changing the opening degree of the inlet regulating valve, so that the fluctuation of the steam pressure is within the allowable range. Specifically, when the steam pressure is greater than the fluctuation limit, the inlet regulating valve of the steam turbine is opened, and when the steam pressure is less than the fluctuation limit, the inlet regulating valve of the steam turbine is closed.

[0080] Further, the feedwater controller is used to determine the first opening degree signal according to the electric boiler liquid level difference signal, the feedwater flow signal and the steam flow signal, comprising: determining the expected feedwater flow signal for compensating the liquid level fluctuation of the electric boiler according to the electric boiler liquid level difference signal; determining the first opening degree signal according to the expected feedwater flow signal, the feedwater flow signal and the steam flow signal, so as to realize the supply of the expected feedwater flow.

[0081] Figure 4 is the schematic diagram of the three-impulse cascade-feedforward composite control method of the feedwater controller provided by the application, as shown in Figure 4As shown, the electric boiler liquid level controller receives an electric boiler liquid level difference signal formed by the difference between the electric boiler set liquid level and the electric boiler measured liquid level, adopts a PID control or neural network control strategy, and online calculates an expected feedwater flow signal required to compensate for the liquid level fluctuation of the electric boiler, the feedwater regulating valve opening degree controller receives the expected feedwater flow signal, the feedwater flow signal, and the steam flow signal, adopts a PI control or other advanced control strategy, and online calculates a first opening degree signal of the feedwater regulating valve required to provide the expected feedwater flow, and the first opening degree signal of the feedwater regulating valve drives the feedwater regulating valve to act to realize feedwater flow regulation. The steam flow signal feedforward is set to cope with the steam flow fluctuation caused by the sudden action of the steam turbine inlet regulating valve, and eliminates the disturbance of the steam flow to the electric boiler liquid level.

[0082] The feedforward control link is set to further improve the response speed of the electric boiler feedwater control and reduce the liquid level fluctuation of the electric boiler, adopts a PI (proportional integral) control strategy, online calculates a second opening degree signal of the feedwater regulating valve according to the second steam pressure difference signal, and the second opening degree signal drives the feedwater regulating valve to act to realize feedwater flow regulation. The feedforward control link can issue a feedwater flow compensation action instruction when the second steam pressure difference signal exists, compared with the electric boiler feedwater controller which needs to wait until the electric boiler appears a liquid level difference or the steam flow fluctuation feedforward compensation before acting, the feedforward control link directly and immediately responds to the external load power signal, which can effectively improve the response speed of the electric boiler feedwater control and reduce the liquid level fluctuation of the pressure difference.

[0083] The feedwater controller further includes a feedwater pump rotating speed controller corresponding to the fourth control module on the system side, which is used to determine a rotating speed signal of the feedwater pump according to a pressure difference error of the feedwater regulating valve, and adjust the rotating speed of the feedwater pump so that the pressure difference error is less than a preset threshold value; the pressure difference error is the difference between a pressure difference set value and a pressure difference measured value of the feedwater regulating valve.

[0084] Specifically, the feedwater pump rotating speed controller receives a pressure difference error signal formed by the difference between the pressure difference set value and the pressure difference measured value of the feedwater regulating valve, adopts a PI control or other advanced control strategy, and online calculates a feedwater pump rotating speed signal required to meet the pressure difference set value of the feedwater regulating valve, to ensure that the feedwater pressure and the pressure difference before and after the feedwater regulating valve meet the feedwater control performance requirements.

[0085] It should be noted that the thermal power generating unit control system in the mode of following the boiler provided in the embodiments of the present application can execute the thermal power generating unit control method in the mode of following the boiler as described in any of the above embodiments when specifically running, and details are not repeated.

[0086] In summary, the application provides a method and system for controlling a thermal power unit in a machine-following-furnace mode, and the control system designed based on the method can include an electric power controller, a feedwater controller, a steam turbine controller, a nonlinear limiting control link, a feedforward control link, a proportional-derivative control link, a pressure disturbance control link, and control objects (thyristor / contactors, electric boilers, steam turbine generators, feedwater pumps, feedwater regulating valves, and admission regulating valves). A steam pressure signal enters the pressure disturbance control link, and the output signal of the pressure disturbance control link and a power difference signal are processed by an adder and then enter the electric power controller. A load power signal enters the proportional-derivative control link, and the output signal of the electric power controller and the output signal of the proportional-derivative control link are processed by an adder, and then a total thyristor / contactor control action signal is output to regulate the electric power output. The power difference signal enters the nonlinear limiting control link, and the output signal of the nonlinear limiting control link, the steam pressure signal, and a steam pressure set signal are processed by an adder and then serve as a total pressure difference signal. The total pressure difference signal enters the steam turbine controller to output an admission regulating valve opening action instruction. The electric boiler liquid level signal, the steam flow signal, the feedwater flow signal, and the electric boiler liquid level set signal enter the feedwater controller, and the total pressure difference signal enters the feedforward control link. The output signal of the feedwater controller and the output signal of the feedforward control link are processed by an adder, and then a total feedwater regulating valve opening signal is output to regulate the feedwater flow, so that the coordinated control objectives of load power tracking performance, electric boiler liquid level and steam pressure fluctuation, and feedwater control and electric power control response speed are achieved.

[0087] Figure 5 is a structural schematic diagram of an electronic device provided by the application, as Figure 5As shown, the electronic device can include a processor 510, a communications interface 520, a memory 530, and a communications bus 540, wherein the processor 510, the communications interface 520, and the memory 530 complete mutual communication through the communications bus 540. The processor 510 can invoke a logical instruction in the memory 530 to execute a method for controlling a thermal power generating unit in a machine following furnace mode, the method including: controlling a heating control device to control an electric heating power of an electric boiler according to a first control action signal and a second control action signal; wherein the first control action signal is generated according to a sum of a steam pressure disturbance compensation signal and a power difference signal, and the second control action signal is generated according to a load power signal of a steam turbine using a proportional differential strategy; wherein the steam pressure disturbance compensation signal is determined according to a steam pressure signal and is used to compensate for a change disturbance of the power difference signal, and the power difference signal is a difference between the load power signal of the steam turbine and a real power signal; determining a second steam pressure difference signal according to a first steam pressure difference signal and a pressure difference adjustment signal to control an opening degree of an admission adjustment valve of the steam turbine; wherein the first steam pressure difference signal is a difference between a steam pressure preset signal and the steam pressure signal, and the pressure adjustment signal is an output signal when the power difference signal is used as an input signal of a two-way amplitude limiting proportional device; controlling an opening degree of a feedwater adjustment valve of a feedwater pump according to a first opening degree signal and a second opening degree signal; wherein the first opening degree signal is determined according to an electric boiler liquid level difference signal, a feedwater flow signal, and a steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

[0088] In another aspect, the present application also provides a computer program product, which comprises a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions which, when executed by a computer, enable the computer to perform the method of controlling a thermal power generating unit in a machine-following furnace mode as provided by any of the above embodiments, the method comprising: controlling a heating control device to control an electric heating power of an electric boiler according to a first control action signal and a second control action signal; wherein the first control action signal is generated according to a sum of a steam pressure disturbance compensation signal and a power difference signal, and the second control action signal is generated according to a load power signal of a steam turbine using a proportional-derivative strategy; wherein the steam pressure disturbance compensation signal is determined according to a steam pressure signal to compensate for a variation disturbance of the power difference signal, and the power difference signal is a difference between the load power signal of the steam turbine and a real power signal; determining a second steam pressure difference signal according to a first steam pressure difference signal and a pressure difference regulation signal to control an opening degree of an admission regulating valve of the steam turbine; wherein the first steam pressure difference signal is a difference between a steam pressure preset signal and the steam pressure signal, and the pressure regulation signal is an output signal when the power difference signal is used as an input signal of a two-way amplitude limiting proportional regulator; controlling the opening degree of a feedwater regulating valve of a feedwater pump according to a first opening degree signal and a second opening degree signal; wherein the first opening degree signal is determined according to an electric boiler liquid level difference signal, a feedwater flow signal and a steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

[0089] In yet another aspect, the present application also provides a non-transitory computer readable storage medium having stored thereon a computer program, which, when executed by a processor, implements a method for controlling a thermal power generating unit in a machine-follows-furnace mode, the method comprising: controlling a heating control device to control an electric heating power of an electric boiler according to a first control action signal and a second control action signal; wherein the first control action signal is generated according to a sum of a steam pressure disturbance compensation signal and a power difference signal, and the second control action signal is generated according to a load power signal of a steam turbine using a proportional-derivative strategy; wherein the steam pressure disturbance compensation signal is determined according to a steam pressure signal and is used to compensate for a change disturbance of the power difference signal, and the power difference signal is a difference between the load power signal of the steam turbine and a real power signal; determining a second steam pressure difference signal according to a first steam pressure difference signal and a pressure difference adjustment signal to control an opening degree of an admission regulating valve of the steam turbine; wherein the first steam pressure difference signal is a difference between a steam pressure preset signal and the steam pressure signal, and the pressure adjustment signal is an output signal when the power difference signal is used as an input signal of a two-way amplitude limiting proportional amplifier; controlling an opening degree of a feedwater regulating valve of a feedwater pump according to a first opening degree signal and a second opening degree signal; wherein the first opening degree signal is determined according to an electric boiler liquid level difference signal, a feedwater flow signal and a steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

[0090] The apparatus embodiments described above are merely illustrative, wherein the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment. Those skilled in the art can understand and implement without creative labor.

[0091] From the above description of the embodiments, those skilled in the art can clearly understand that the embodiments can be implemented by means of software plus necessary general hardware platforms, and of course can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part that contributes to the prior art, can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in the various embodiments or some parts of the embodiments.

[0092] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling a thermal power generating unit in a back-to-back mode, characterized in that, The method comprises the following steps: controlling the heating control device to control the electric heating power of the electric boiler according to the first control action signal and the second control action signal; wherein the first control action signal is generated according to the sum of the steam pressure disturbance compensation signal and the power difference signal, and the second control action signal is generated according to the load power signal of the steam turbine by using a proportional differential strategy; wherein the steam pressure disturbance compensation signal is determined according to the steam pressure signal and is used to compensate the variation disturbance of the power difference signal, and the power difference signal is the difference between the load power signal of the steam turbine and the actual power signal; determining the second steam pressure difference signal according to the first steam pressure difference signal and the pressure difference adjustment signal, so as to control the opening degree of the inlet regulating valve of the steam turbine; wherein the first steam pressure difference signal is the difference between the steam pressure preset signal and the steam pressure signal, and the pressure adjustment signal is the output signal when the power difference signal is used as the input signal of the proportional amplifier with bidirectional amplitude limiting; controlling the opening degree of the feedwater regulating valve of the feedwater pump according to the first opening degree signal and the second opening degree signal; wherein the first opening degree signal is determined according to the electric boiler liquid level difference signal, the feedwater flow signal and the steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

2. The method of controlling a fossil-fueled power plant according to claim 1, wherein determining the steam pressure disturbance compensation signal according to the steam pressure signal to compensate the variation disturbance of the power difference signal, comprising: generating the steam pressure disturbance compensation signal according to the steam pressure signal by using a first-order inertia differential control strategy; the relationship of the first-order inertia differential control strategy is as follows: ； wherein is an inertial time constant, is a proportional gain constant, s is a Laplace operator; the expression of the vapour pressure perturbation compensation signal is: ； wherein Pv is the vapor pressure signal; when the steam turbine inlet regulating valve is in action, the inertia time constant and the proportional gain constant are set to make the sum of the steam pressure disturbance compensation signal and the power difference signal be 0.

3. The method of controlling a fossil-fueled power plant according to claim 1, wherein the steps of generating the pressure adjustment signal by using the proportional amplifier with bidirectional amplitude limiting, comprising: inputting the power difference signal as the input signal into the proportional amplifier with bidirectional amplitude limiting; when the power difference signal is in the amplitude limiting region of the proportional amplifier with bidirectional amplitude limiting, the pressure adjustment signal changes linearly in positive correlation with the change of the power difference signal; when the power difference signal is in the horizontal saturation region on both sides of the proportional amplifier with bidirectional amplitude limiting, the pressure adjustment signal remains the current pressure adjustment signal with the change of the power difference signal.

4. The method of controlling a fossil-fueled power plant according to claim 1, wherein determining the first opening degree signal according to the electric boiler liquid level difference signal, the feedwater flow signal and the steam flow signal, comprising: determining the expected feedwater flow signal for compensating the liquid level fluctuation of the electric boiler according to the electric boiler liquid level difference signal; determining the first opening degree signal according to the expected feedwater flow signal, the feedwater flow signal and the steam flow signal, so as to realize the supply of the expected feedwater flow; and determining the second opening degree signal according to the second steam pressure difference signal, comprising: determining the second opening degree signal according to the second steam pressure difference signal by using a proportional integral strategy.

5. The method of controlling a fossil-fueled power plant according to claim 1, wherein further comprising: determining the rotating speed signal of the feedwater pump according to the differential pressure error of the feedwater regulating valve, and adjusting the rotating speed of the feedwater pump to make the differential pressure error less than a preset threshold value; the differential pressure error is the difference between the differential pressure set value and the differential pressure measured value of the feedwater regulating valve.

6. The method of controlling a fossil-fueled power plant according to claim 1, wherein the heating control device is a thyristor or a contactor.

7. A control system for a fossil-fueled steam power plant in a backstop mode, characterized in that ​ The first control module is configured to control the heating control device to control the electric heating power of the electric boiler according to a first control action signal and a second control action signal, wherein the first control action signal is generated according to a sum of a steam pressure disturbance compensation signal and a power difference signal, and the second control action signal is generated according to a load power signal of the steam turbine by using a proportional differential strategy, wherein the steam pressure disturbance compensation signal is determined according to a steam pressure signal and is used to compensate for the change disturbance of the power difference signal, and the power difference signal is a difference between the load power signal of the steam turbine and an actual power signal; The second control module is configured to determine a second steam pressure difference signal according to a first steam pressure difference signal and a pressure difference adjustment signal, so as to control the opening degree of the inlet adjusting valve of the steam turbine, wherein the first steam pressure difference signal is a difference between a steam pressure preset signal and a steam pressure signal, and the pressure adjustment signal is an output signal when the power difference signal is used as an input signal of a two-way amplitude limiting proportional device; The third control module is configured to control the opening degree of the feedwater adjusting valve of the feedwater pump according to a first opening degree signal and a second opening degree signal, wherein the first opening degree signal is determined according to an electric boiler liquid level difference signal, a feedwater flow signal and a steam flow signal, and the second opening degree signal is determined according to the second steam pressure difference signal.

8. The control system for a fossil-fueled steam power plant according to claim 7, characterized in that The system further comprises a fourth control module; The fourth control module is configured to determine a rotation speed signal of the feedwater pump according to a differential pressure error of the feedwater adjusting valve, and adjust the rotation speed of the feedwater pump, so that the differential pressure error is less than a preset threshold value. The differential pressure error is a difference between a differential pressure set value and a differential pressure actual value of the feedwater adjusting valve.

9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the computer program to realize the steps of the method for controlling the thermal power generating unit in the machine-following boiler mode according to any one of claims 1 to 6. 10.A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the method for controlling the thermal power generating unit in the machine-following boiler mode according to any one of claims 1 to 6.

Images