Method and system for determining the impact of transient system frequency changes on thermal effects of thermal power units

Abstract

The present invention discloses a method for determining the impact of transient system frequency changes on the thermal effect of a thermal power unit, comprising obtaining data information of a target thermal power unit; constructing a typical model of a steam turbine-speed governor of the target thermal power unit; calculating the main steam flow data of the steam turbine input of the target thermal power unit; calculating parameter information after considering the thermal effect of the boiler using the typical model of the steam turbine-speed governor; calculating the thermal effect evaluation index and system frequency safety margin index of the target thermal power unit; calculating the thermal effect frequency response index of the target thermal power unit and completing the determination of the impact of transient system frequency changes on the thermal effect of the target thermal power unit. The present invention also discloses a system for implementing the method for determining the impact of transient system frequency changes on the thermal effect of a thermal power unit. The present invention not only realizes the determination of the impact of transient system frequency changes on the thermal effect of a thermal power unit, but also has higher reliability and better accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of electrical automation, and in particular relates to a method and system for determining the influence of frequency changes in a transient process system on the thermal effect of a thermal power unit. Background Art

[0002] With the development of economy and technology and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring a stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] Power system electromechanical transient simulation and analysis is of great significance to power systems. Currently, PSS / E is the most commonly used transient simulation software for power systems. This software provides a Python-based application program interface (API), enabling data exchange between Python and PSS / E. The API allows for direct function calls, enabling PSS / E parameter configuration and control, including power flow calculations and transient simulations.

[0004] With the current evolution of power systems and the integration of new energy systems, the adaptability of conventional power system frequency security and stability analysis models and methods is facing significant challenges. While the existing PSS / E software for power systems includes a boiler model and can simulate the dynamic behavior of boiler fuel, this model does not account for the impact of frequency variations on the boiler's thermal state and auxiliary unit output. Consequently, it is unable to accurately simulate the system's frequency characteristics and analyze frequency security and stability characteristics when experiencing large frequency excursions. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a method for determining the influence of transient system frequency changes on thermal effects of thermal power units with high reliability and good accuracy.

[0006] A second object of the present invention is to provide a system for realizing a method for determining the influence of the transient system frequency change on the thermal effect of a thermal power unit.

[0007] The method for determining the impact of transient system frequency changes on thermal effects of thermal power units provided by the present invention comprises the following steps:

[0008] S1. Obtain data information on the target thermal power unit;

[0009] S2. Based on the data information obtained in step S1, a typical model of the steam turbine of the target thermal power unit is constructed in the power system transient simulation software;

[0010] S3. According to the data information obtained in step S1, the main steam flow data of the steam turbine input of the target thermal power unit is calculated;

[0011] S4. Based on the data information obtained in step S3, the typical model of the steam turbine - governor constructed in step S2 is combined to calculate the parameter information after considering the thermal effect of the boiler;

[0012] S5. Based on the data information obtained in step S4, the thermal effect evaluation index and the system frequency safety margin index of the target thermal power unit are calculated;

[0013] S6. Based on the data information obtained in step S5, the thermal effect frequency response index of the target thermal power unit is calculated, and the impact of the transient system frequency change on the thermal effect of the target thermal power unit is determined.

[0014] According to the data information obtained in step S1, step S2 constructs a typical model of the steam turbine-speed governor of the target thermal power unit in the power system transient simulation software, which specifically includes the following steps:

[0015] The typical model of the steam turbine-governor of the target thermal power unit is constructed. The processing process includes:

[0016] The per-unit value of the system angular frequency deviation Δω is amplified and inverted by the frequency deviation amplification factor K when the boiler thermal effect is not considered, and then compared with the actual turbine valve opening C V The opposite value of the thermal power unit and the initial power P0 are added to obtain the first transfer signal u C for u C =-KΔω+P0-C V ;

[0017] Internal transmission signal u C The second transmission signal u is obtained through the inertia link processing of the speed regulator B for T3 is the time constant of the inertia link of the speed regulator;

[0018] The second transmission signal u B After the first limiting link processing, the second limited transmission signal u' is obtained B for Among them U O is the upper limit value of the first limiting link, U C is the lower limit value of the first limiting link;

[0019] The second limited transfer signal u' B At time t, after simulation step length Δt, the change in the turbine valve opening ΔC is obtained. V ΔC V =u' B Δt;

[0020] Turbine valve opening change ΔC V After the integral link processing, the unlimited turbine valve opening u is obtained A for u A =C V,int +ΔC V , C V,int is the value of the turbine regulating valve opening at time t;

[0021] Unlimited steam turbine regulating valve opening u A After the second limiting link processing, the actual turbine valve opening is obtained Among them, P MAX is the maximum opening of the turbine regulating valve, P MIN is the minimum value of the turbine regulating valve opening;

[0022] Actual throttle opening of steam turbine C V and boiler thermal state parameters are input into the turbine model to obtain the final turbine output power P m ;

[0023] During the operation of the steam turbine, the main steam flow rate D te is the boiler main steam pressure P t and the actual throttle opening of the turbine C V The product of the steam turbine and speed governor of the target thermal power unit is set to t is 1, so we get D te =C V ·P t =C V ;

[0024] Since there is C in the numerical V =D te , so there is ΔC V =ΔD te ; ΔD te is the change in main steam flow rate input to the steam turbine;

[0025] WhenU C ≤u B ≤U O When ΔD te =u B Δt;

[0026] From this we get

[0027] Step S3, based on the data information obtained in step S1, calculates the main steam flow rate data input to the steam turbine of the target thermal power unit, and specifically includes the following steps:

[0028] According to the data information obtained in step S1, the Python program is used to calculate the main steam flow data D of the turbine input of the target thermal power unit based on the boiler thermal state, governor dynamics, boiler control system and frequency deviation signal. t ' e .

[0029] Step S4, based on the data information obtained in step S3 and in combination with the typical model of the steam turbine-governor constructed in step S2, calculates parameter information after considering the thermal effect of the boiler, specifically including the following steps:

[0030] Step S3 obtains the main steam flow data D of the steam turbine input of the target thermal power unit after considering the boiler thermal effect. t ' e ;

[0031] In order to combine the typical model of turbine-governor constructed in step S2, there exists D te =D t ' e and ΔD te =ΔD t ' e ; where ΔD t ' e The change value of the main steam flow data input to the steam turbine of the target thermal power unit after considering the boiler thermal effect;

[0032] WhenU C ≤u B ≤U O When D t ' e and ΔD t ' e Substitute into the calculation formula get Among them, K' is the frequency deviation amplification factor when considering the boiler thermal effect after the model is combined;

[0033] according to Order passed The calculated u B , and through The calculated u B are equal, so the expression of K' is calculated as

[0034]

[0035] Step S5, based on the data information obtained in step S4, calculates the thermal effect evaluation index and the system frequency safety margin index of the target thermal power unit, and specifically includes the following steps:

[0036] The thermal effect evaluation index α of the target thermal power unit is calculated using the following formula:

[0037]

[0038] Where K' min is the minimum value of the frequency deviation amplification factor after the model combination when considering the boiler thermal effect, calculated based on the data information obtained in step S4;

[0039] The system frequency safety margin index β of the target thermal power unit is calculated using the following formula:

[0040]

[0041] Where f nadir is the minimum value of the system transient frequency; f cr,1 is the frequency threshold value of the first round of low-frequency load shedding of the system; f N is the rated frequency value of the system.

[0042] Step S6, based on the data information obtained in step S5, calculates the thermal effect frequency response index of the target thermal power unit and determines the impact of the transient system frequency change on the thermal effect of the target thermal power unit. Specifically, the steps include:

[0043] The thermal effect frequency response index η of the target thermal power unit is calculated as follows:

[0044] The following rules are used to determine the impact of transient system frequency changes on the thermal effect of the target thermal power unit:

[0045] The smaller the value of η is, the smaller the impact of the transient system frequency change on the thermal effect of the target thermal power unit is, and the better the transient response capability of the target thermal power unit is.

[0046] The larger the value of η is, the greater the impact of the transient system frequency change on the thermal effect of the target thermal power unit is, and the worse the transient response capability of the target thermal power unit is.

[0047] The present invention also provides a system for realizing a method for determining the influence of the frequency change of the transient process system on the thermal effect of the thermal power unit, comprising a data acquisition module, a model construction module, a flow calculation module, a parameter calculation module, an index calculation module and an influence determination module; the data acquisition module, the model construction module, the flow calculation module, the parameter calculation module, the index calculation module and the influence determination module are connected in series in sequence; the data acquisition module is used to obtain the data information of the target thermal power unit and upload the data information to the model construction module; the model construction module is used to construct a typical model of the steam turbine-speed governor of the target thermal power unit in the power system transient simulation software according to the received data information and the acquired data information, and upload the data information to the flow calculation module; the flow calculation module is used to construct a typical model of the steam turbine-speed governor of the target thermal power unit according to the received data information and the acquired data information , calculate the main steam flow data of the turbine input of the target thermal power unit, and upload the data information to the parameter calculation module; the parameter calculation module is used to calculate the parameter information after considering the boiler thermal effect based on the received data information and the obtained data information, combined with the turbine-speed governor typical model constructed in step S2, and upload the data information to the index calculation module; the index calculation module is used to calculate the thermal effect evaluation index and the system frequency safety margin index of the target thermal power unit based on the received data information and the obtained data information, and upload the data information to the impact judgment module; the impact judgment module is used to calculate the thermal effect frequency response index of the target thermal power unit based on the received data information and the obtained data information, and complete the judgment of the impact of the transient process system frequency change on the thermal effect of the target thermal power unit.

[0048] The method and system for determining the impact of transient system frequency changes on the thermal effects of thermal power units provided by the present invention, through the construction of a typical turbine-governor model of the target thermal power unit, as well as joint simulation and corresponding calculations, not only realizes the determination of the impact of transient system frequency changes on the thermal effects of thermal power units, but also has higher reliability and better accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the process flow of the present invention.

[0050] Figure 2 The figure is a schematic diagram of the model structure of a typical model of a steam turbine-speed governor of a thermal power unit according to the method of the present invention.

[0051] Figure 3 Schematic diagram of the model structure of the joint model of the method of the present invention.

[0052] Figure 4 This is a schematic diagram of the system structure of an IEEE 10 machine 39 node system according to an embodiment of the method of the present invention.

[0053] Figure 5 Schematic diagram of simulation comparison of the implementation method and extended model of the method embodiment of the present invention.

[0054] Figure 6 Schematic diagram of the system frequency response curve under fault scenario 1 of an embodiment of the method of the present invention.

[0055] Figure 7 Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0056] like Figure 1 The method of the present invention is shown as a flow chart: The method disclosed in the present invention for determining the impact of transient system frequency changes on thermal effects of thermal power generation units comprises the following steps:

[0057] S1. Obtain data information on the target thermal power unit;

[0058] S2. Based on the data information obtained in step S1, a typical model of the steam turbine-governor of the target thermal power unit is constructed in the power system transient simulation software; specifically comprising the following steps:

[0059] The typical model of steam turbine-speed governor of the target thermal power unit is constructed (such as Figure 2 The processing process includes:

[0060] The per-unit value of the system angular frequency deviation Δω is amplified and inverted by the frequency deviation amplification factor K when the boiler thermal effect is not considered, and then compared with the actual turbine valve opening C V The opposite value of the thermal power unit and the initial power P0 are added to obtain the first transfer signal u C ( Figure 2 The signal at point C is u C =-KΔω+P0-C V ;

[0061] Internal transmission signal u C The second transmission signal u is obtained through the inertia link processing of the speed regulator B ( Figure 2 The signal at point B in the middle is T3 is the time constant of the inertia link of the speed regulator;

[0062] The second transmission signal u B After the first limiting link processing, the second limited transmission signal u' is obtained B for Among them U O is the upper limit value of the first limiting link, U C is the lower limit value of the first limiting link;

[0063] The second limited transfer signal u' BAt time t, after simulation step length Δt, the change in the turbine valve opening ΔC is obtained. V ΔC V =u' B Δt;

[0064] Turbine valve opening change ΔC V After the integral link processing, the unlimited turbine valve opening u is obtained A for u A =C V,int +ΔC V , C V,int is the value of the turbine regulating valve opening at time t;

[0065] Unlimited steam turbine regulating valve opening u A After the second limiting link processing, the actual turbine valve opening C is obtained V ( Figure 2 The signal at point A) is Among them, P MAX is the maximum opening of the turbine regulating valve, P MIN is the minimum value of the turbine regulating valve opening;

[0066] Actual throttle opening of steam turbine C V and boiler thermal state parameters are input into the turbine model to obtain the final turbine output power P m ;

[0067] During the operation of the steam turbine, the main steam flow rate D te is the boiler main steam pressure P t and the actual throttle opening of the turbine C V The product of the steam turbine and speed governor of the target thermal power unit is set to t is 1, so we get D te =C V ·P t =C V ;

[0068] Since there is C in the numerical V =D te , so there is ΔC V =ΔD te ; ΔD te is the change in main steam flow rate input to the steam turbine;

[0069] WhenU C ≤u B ≤U O When ΔD te =u B Δt;

[0070] From this we get

[0071] S3. According to the data information obtained in step S1, the main steam flow data of the steam turbine input of the target thermal power unit is calculated; specifically comprising the following steps:

[0072] In a typical model of a thermal power plant turbine-governor, the angular frequency deviation signal is used as input to calculate the rate of change of the turbine throttle valve opening, which in turn determines the throttle valve opening. This, in turn, determines the main steam flow rate input to the turbine under the assumed main steam pressure. Because the main steam pressure is typically assumed to be a constant value of 1, in this typical model of a thermal power plant turbine-governor, the throttle valve opening and its rate of change are equal to the turbine main steam flow rate and its rate of change, respectively.

[0073] According to the data information obtained in step S1, the Python program is used to calculate the main steam flow data D of the turbine input of the target thermal power unit based on the boiler thermal state, governor dynamics, boiler control system and frequency deviation signal. t ' e ;

[0074] In specific implementation, for the existing thermal power unit control system, the coal intake, water intake, and main steam flow rate data D of the thermal power unit can be calculated based on the boiler thermal state, governor dynamics, boiler control system, and frequency deviation signal. t ' e , which can reflect the impact of system disturbances on the power generation process of thermal power units; therefore, the present invention implements this part of the content in a Python program, and then feeds it back to the model parameters in PSS / E through the API interface, so that the model in PSS / E can consider the impact of changes in the coal and water intake of the thermal power unit on the thermal state of the boiler and the boiler control of the thermal power unit during the calculation process;

[0075] S4. Based on the data information obtained in step S3, the typical model of the steam turbine-speed governor constructed in step S2 (such as Figure 3 ), calculate the parameter information after considering the boiler thermal effect; specifically, the steps include:

[0076] Step S3 obtains the main steam flow data D of the steam turbine input of the target thermal power unit after considering the boiler thermal effect. t ' e In order to use Figure 3 The model structure in the red box realizes function expansion and joint simulation, that is, in order to combine the typical model of steam turbine-speed governor constructed in step S2, there is D te =D t ' e and ΔD te =ΔDt ' e ; where ΔD t ' e The change value of the main steam flow data input to the steam turbine of the target thermal power unit after considering the boiler thermal effect;

[0077] WhenU C ≤u B ≤U O When D t ' e and ΔD t ' e Substitute into the calculation formula get Among them, K' is the frequency deviation amplification factor when considering the boiler thermal effect after the model is combined;

[0078] according to Order passed The calculated u B , and through The calculated u B are equal, so the expression of K' is calculated as

[0079]

[0080] S5. Based on the data information obtained in step S4, the thermal effect evaluation index and the system frequency safety margin index of the target thermal power unit are calculated; specifically comprising the following steps:

[0081] The thermal effect evaluation index α of the target thermal power unit is calculated using the following formula:

[0082]

[0083] Where K' min is the minimum value of the frequency deviation amplification coefficient when considering the boiler thermal effect after the combined model is calculated based on the data information obtained in step S4; according to the thermal effect evaluation index α, it can be seen that when the thermal effect evaluation index value of the thermal power unit is larger, the degree of change in the boiler heat storage capacity during the transient process is greater, and the change in the boiler main steam pressure is greater;

[0084] The system frequency safety margin index β of the target thermal power unit is calculated using the following formula:

[0085]

[0086] Where f nadir is the minimum value of the system transient frequency; f cr1 is the frequency threshold value of the first round of low-frequency load shedding of the system; f N is the rated frequency value of the system;

[0087] S6. Based on the data information obtained in step S5, the thermal effect frequency response index of the target thermal power unit is calculated, and the impact of the transient system frequency change on the thermal effect of the target thermal power unit is determined; specifically, the following steps are included:

[0088] The thermal effect frequency response index η of the target thermal power unit is calculated as follows:

[0089] The following rules are used to determine the impact of transient system frequency changes on the thermal effect of the target thermal power unit:

[0090] The smaller the value of η is, the smaller the impact of the transient system frequency change on the thermal effect of the target thermal power unit is, and the better the transient response capability of the target thermal power unit is.

[0091] The larger the value of η is, the greater the impact of the transient system frequency change on the thermal effect of the target thermal power unit is, and the worse the transient response capability of the target thermal power unit is.

[0092] The method of the present invention is further described below with reference to an embodiment:

[0093] Take the IEEE 39-node system as an example. Figure 4 As shown in the figure; in the 39-node system, the total installed capacity of the units is 6800MW and the total load is 6140.8MW, among which nodes 30 to 39 are generator nodes and all the units are thermal power units.

[0094] Set the disturbance to 0.1pu, and the frequency response curve of the system is as follows Figure 5 As shown in the simulation results, it can be seen that the method of the present invention is feasible and has good simulation accuracy.

[0095] A fault scenario was set up: the removal of a generator at node 38 resulted in a system active power loss of 830 MW, a disturbance equivalent to 12.21% of the system's installed capacity. The frequency response curves of different models were analyzed for the same fault scenario, taking into account the thermal effects of boiler transients. Model 1: a conventional PSS / E system frequency response model; Model 2: a frequency response model based on Model 1 with an expanded boiler thermal effect model; and Model 3: an expanded frequency response model that considers the varying boiler thermal effect model.

[0096] When the boiler thermal effect is not initially considered, the frequency deviation amplification factor K is set to 20. Under fault scenario 1, the system frequency response curves of different simulation models are analyzed using PSS / E software, such as Figure 6 shown.

[0097] Model 1: PSS / E conventional system frequency response model:

[0098]

[0099] Model 2: Based on Model 1, the frequency response model of the boiler thermal effect model is expanded:

[0100]

[0101] Model 2: When in the initial state, change the boiler thermal state to non-rated state:

[0102]

[0103] Model 3: Extended frequency response model considering boiler thermal effect variation model:

[0104]

[0105]

[0106] From the above analysis, it can be seen that when the boiler thermal effect is not considered, the frequency deviation amplification coefficient is a constant value. At this time, the boiler of the thermal power unit has good heat storage capacity and can respond well to the transient response process of the system. When the boiler thermal effect is considered, the frequency deviation amplification coefficient changes with the transient process, and the initial thermal effect state of the boiler has a greater impact on the transient response process of the thermal power unit.

[0107] The scheme of the present invention can further quantitatively analyze the impact of boiler thermal effect changes on system transient response through changes in frequency deviation amplification coefficient. At the same time, it can quantitatively analyze the thermal effect frequency response index of the thermal power unit, and then analyze the impact of system frequency changes on thermal power unit boiler heat storage.

[0108] like Figure 7The figure shows a schematic diagram of the functional modules of the system of the present invention: the system disclosed by the present invention for realizing the method for determining the influence of the frequency change of the transient process system on the thermal effect of the thermal power unit comprises a data acquisition module, a model construction module, a flow calculation module, a parameter calculation module, an index calculation module and an influence determination module; the data acquisition module, the model construction module, the flow calculation module, the parameter calculation module, the index calculation module and the influence determination module are connected in series in sequence; the data acquisition module is used to obtain the data information of the target thermal power unit and upload the data information to the model construction module; the model construction module is used to construct a typical model of the turbine-speed governor of the target thermal power unit in the power system transient simulation software according to the received data information and the acquired data information, and upload the data information to the flow calculation module; the flow calculation module is used to, according to the received data information, Based on the acquired data information, the main steam flow data of the turbine input of the target thermal power unit is calculated, and the data information is uploaded to the parameter calculation module; the parameter calculation module is used to calculate the parameter information after considering the thermal effect of the boiler based on the received data information and the obtained data information, combined with the typical model of the turbine-speed governor constructed in step S2, and upload the data information to the index calculation module; the index calculation module is used to calculate the thermal effect evaluation index and the system frequency safety margin index of the target thermal power unit based on the received data information and the obtained data information, and upload the data information to the impact judgment module; the impact judgment module is used to calculate the thermal effect frequency response index of the target thermal power unit based on the received data information and the obtained data information, and complete the judgment of the impact of the transient process system frequency change on the thermal effect of the target thermal power unit.

Claims

1. A method for determining the impact of transient system frequency changes on thermal effects of thermal power units, comprising the following steps: S1. Obtain data information on the target thermal power unit; S2. Based on the data information obtained in step S1, a typical model of the steam turbine of the target thermal power unit is constructed in the power system transient simulation software; S3. According to the data information obtained in step S1, the main steam flow data of the steam turbine input of the target thermal power unit is calculated; S4. Based on the data information obtained in step S3, the typical model of the steam turbine-governor constructed in step S2 is combined to calculate the parameter information after considering the thermal effect of the boiler; specifically, the steps include: Step S3 obtains the main steam flow data D' of the target thermal power unit's steam turbine input after considering the boiler thermal effect. te ; In order to combine the typical model of turbine-governor constructed in step S2, there exists D te =D' te and ΔD te =ΔD' te ; Where ΔD' te is the change value of the main steam flow data input to the steam turbine of the target thermal power unit after considering the boiler thermal effect; D te is the main steam flow of the steam turbine; ΔD te is the change in main steam flow rate input to the steam turbine; WhenU C ≤u B ≤U O When D' te and ΔD' te Substitute into the calculation formula get Among them, K' is the frequency deviation amplification coefficient when considering the boiler thermal effect after the model is combined; U O is the upper limit value of the first limiting link; U C is the lower limit value of the first limiting link; u B is the second transfer signal; Δω is the per-unit value of the system angular frequency deviation; K is the frequency deviation amplification factor when the boiler thermal effect is not considered; P0 is the initial power of the thermal power unit; T3 is the time constant of the inertia link of the speed regulator; Δt is the simulation step size; according to Order passed The calculated u B , and through The calculated u B are equal, so the expression of K' is calculated as S5. Based on the data information obtained in step S4, the thermal effect evaluation index and the system frequency safety margin index of the target thermal power unit are calculated; S6. Based on the data information obtained in step S5, the thermal effect frequency response index of the target thermal power unit is calculated, and the impact of the transient system frequency change on the thermal effect of the target thermal power unit is determined.

2. The method for determining the impact of transient system frequency changes on thermal effects of thermal power units according to claim 1 is characterized in that According to the data information obtained in step S1, step S2 constructs a typical model of the steam turbine-speed governor of the target thermal power unit in the power system transient simulation software, which specifically includes the following steps: The typical model of the steam turbine-governor of the target thermal power unit is constructed. The processing process includes: The per-unit value of the system angular frequency deviation Δω is amplified and inverted by the frequency deviation amplification factor K when the boiler thermal effect is not considered, and then compared with the actual turbine valve opening C V The opposite value of the thermal power unit and the initial power P0 are added to obtain the first transfer signal u C for u C =-KΔω+P0-C V ; The first transmission signal u C The second transmission signal u is obtained through the inertia link processing of the speed regulator B for T3 is the time constant of the inertia link of the speed regulator; The second transmission signal u B After the first limiting link processing, the second limited transmission signal u' is obtained B for Among them U O is the upper limit value of the first limiting link, U C is the lower limit value of the first limiting link; The second limited transfer signal u' B At time t, after simulation step length Δt, the change in the turbine valve opening ΔC is obtained. V ΔC V =u' B Δt; Turbine valve opening change ΔC V After the integral link processing, the unlimited turbine valve opening u is obtained A for u A =C V,int +ΔC V , C V,int is the value of the turbine regulating valve opening at time t; Unlimited steam turbine regulating valve opening u A After the second limiting link processing, the actual turbine valve opening C is obtained V for Among them, P MAX is the maximum opening of the turbine regulating valve, P MIN is the minimum value of the turbine regulating valve opening; Actual throttle opening of steam turbine C V and boiler thermal state parameters are input into the turbine model to obtain the final turbine output power P m ; During the operation of the steam turbine, the main steam flow rate D te is the boiler main steam pressure P t and the actual throttle opening of the turbine C V The product of the steam turbine and speed governor of the target thermal power unit is set to t is 1, so we get D te =C V ·P t =C V ; Since there is C in the numerical V =D te , so there is ΔC V =ΔD te ; ΔD te is the change in main steam flow rate input to the steam turbine; WhenU C ≤u B ≤U O When ΔD te =u B Δt; From this we get 3. The method for determining the impact of transient system frequency changes on thermal effects of thermal power units according to claim 2, characterized in that Step S3, based on the data information obtained in step S1, calculates the main steam flow rate data input to the steam turbine of the target thermal power unit, and specifically includes the following steps: According to the data information obtained in step S1, the Python program is used to calculate the main steam flow data D' of the turbine input of the target thermal power unit based on the boiler thermal state, governor dynamics, boiler control system and frequency deviation signal. te .

4. The method for determining the impact of transient system frequency changes on thermal effects of thermal power units according to claim 3 is characterized in that Step S5, based on the data information obtained in step S4, calculates the thermal effect evaluation index and the system frequency safety margin index of the target thermal power unit, and specifically includes the following steps: The thermal effect evaluation index α of the target thermal power unit is calculated using the following formula: Where K' min is the minimum value of the frequency deviation amplification factor after the model combination when considering the boiler thermal effect, calculated based on the data information obtained in step S4; The system frequency safety margin index β of the target thermal power unit is calculated using the following formula: Where f nadir is the minimum value of the system transient frequency; f cr,1 is the frequency threshold value of the first round of low-frequency load shedding of the system; f N is the rated frequency value of the system.

5. The method for determining the impact of transient system frequency changes on thermal effects of thermal power units according to claim 4 is characterized in that Step S6, based on the data information obtained in step S5, calculates the thermal effect frequency response index of the target thermal power unit and determines the impact of the transient system frequency change on the thermal effect of the target thermal power unit. Specifically, the steps include: The thermal effect frequency response index η of the target thermal power unit is calculated as follows: The following rules are used to determine the impact of transient system frequency changes on the thermal effect of the target thermal power unit: The smaller the value of η is, the smaller the impact of the transient system frequency change on the thermal effect of the target thermal power unit is, and the better the transient response capability of the target thermal power unit is. The larger the value of η is, the greater the impact of the transient system frequency change on the thermal effect of the target thermal power unit is, and the worse the transient response capability of the target thermal power unit is.

6. A system for implementing the method for determining the impact of transient system frequency changes on thermal effects of thermal power units as described in any one of claims 1 to 5, characterized in that It includes a data acquisition module, a model construction module, a flow calculation module, a parameter calculation module, an index calculation module and an impact judgment module; the data acquisition module, the model construction module, the flow calculation module, the parameter calculation module, the index calculation module and the impact judgment module are connected in series in sequence; the data acquisition module is used to obtain data information of the target thermal power unit and upload the data information to the model construction module; the model construction module is used to construct a typical model of the steam turbine-speed governor of the target thermal power unit in the power system transient simulation software based on the received data information and the acquired data information, and upload the data information to the flow calculation module; The flow calculation module is used to calculate the main steam flow data of the steam turbine input of the target thermal power unit according to the received data information and the acquired data information, and upload the data information to the parameter calculation module; The parameter calculation module is used to calculate the parameter information after considering the boiler thermal effect based on the received data information and the typical model of the steam turbine-governor constructed in step S2, and upload the data information to the indicator calculation module; The index calculation module is used to calculate the thermal effect evaluation index and system frequency safety margin index of the target thermal power unit based on the received data information, and upload the data information to the impact judgment module; The impact determination module is used to calculate the thermal effect frequency response index of the target thermal power unit based on the received data information, and complete the determination of the impact of the transient process system frequency change on the thermal effect of the target thermal power unit.

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