Thermal power plant system earthquake vulnerability assessment method based on reliability block diagram and Monte Carlo simulation

Abstract

The invention discloses a thermal power plant system earthquake vulnerability evaluation method based on a reliability block diagram and Monte Carlo simulation. The method comprises the following steps: establishing a reliability block diagram model; defining a residual function state function of the thermal power plant system; determining parameters in the earthquake vulnerability curve of each component in the thermal power plant system; based on the earthquake vulnerability curve, the reliability block diagram model and the residual function state function of each component in the thermal power plant system, calculating failure probability sample points of different residual function states of the thermal power plant system under different earthquake oscillation intensity parameters through a Monte Carlo simulation method; and performing curve nonlinear fitting on the failure probability sample points to obtain earthquake vulnerability curves of different residual function states of the thermal power plant system. According to the thermal power plant system earthquake vulnerability evaluation method, the earthquake vulnerability analysis of the thermal power plant system level can be realized based on the earthquake vulnerability curve of the thermal power plant component level.

Description

Technical Field

[0001] The invention relates to the field of earthquake resistance assessment of power systems, and in particular provides an earthquake vulnerability assessment method for a thermal power plant system based on a reliability block diagram and Monte Carlo simulation. Background Art

[0002] A thermal power plant is an important energy supply facility. It consists of a series of different types of equipment and buildings (structures), which are functionally connected in series or parallel to form a complex system. As an important energy supply method, a thermal power plant is an important node in the power system.

[0003] If an earthquake occurs, thermal power plants will be damaged to varying degrees. Due to their large scale and huge investment, serious damage will cause huge economic losses and affect the restoration of social life order after the earthquake, as well as the smooth implementation of emergency rescue after the earthquake. Therefore, it is urgent and necessary to conduct in-depth research on the seismic vulnerability of thermal power plants, which provides support for ensuring and improving the seismic reliability and safe operation of thermal power plants, and is of great significance to ensuring the safety of energy and power systems under strong earthquakes and the sustainable development of the economy and society.

[0004] Thermal power plant systems are complex and redundant. When an earthquake occurs, some of the systems may be damaged, but the function of the entire system will not be completely lost. Traditional systematic analysis methods have some problems, such as high computational complexity, inability to consider all equipment, or difficulty in finding analytical solutions. Simplified mathematical model algorithms can reduce the amount of calculations, but they are inconsistent with the actual physical model and may affect the accuracy of the assessment. Therefore, when conducting earthquake assessments, how to balance accuracy and computational complexity and choose an appropriate analysis method has become an urgent problem to be solved. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a method for seismic vulnerability assessment of a thermal power plant system based on reliability block diagram and Monte Carlo simulation to solve the problems existing in the prior art.

[0006] The technical solution provided by the present invention is: a method for assessing the seismic vulnerability of a thermal power plant system based on a reliability block diagram and Monte Carlo simulation, comprising:

[0007] Establish a reliability block diagram model based on the physical and functional logical relationships of each component in the thermal power plant system;

[0008] Define a residual function state function of a thermal power plant system, wherein the value of the residual function state function ranges from 0 to 1;

[0009] Determine the parameters in the seismic vulnerability curve of each component in the thermal power plant system, wherein the parameters include μ and β, and the seismic vulnerability curve of each component obeys a logarithmic normal distribution with a logarithmic median of μ and a logarithmic standard deviation of β;

[0010] Based on the seismic vulnerability curves, reliability block diagram models and residual functional state functions of various components in the thermal power plant system, the failure probability sample points of different residual functional states of the thermal power plant system under different seismic motion intensity parameters are calculated by the Monte Carlo simulation method, and the seismic vulnerability curves of different residual functional states of the thermal power plant system are obtained by performing nonlinear curve fitting on the failure probability sample points.

[0011] Preferably, the reliability block diagram model is composed of two most basic structural types, namely, a series structure and a parallel structure, wherein the series structure can only work normally when each unit in the series structure works normally; the parallel structure can work normally when at least one unit in the parallel structure works normally; the components in the thermal power plant system express the logical relationship of the entire thermal power plant system through different combinations of the two basic structural forms; the equipment and structures within the thermal power plant system serve as nodes of the reliability block diagram model.

[0012] Further optimization is performed when defining the residual function state function of the thermal power plant system, based on the reliability block diagram of the thermal power plant system, considering the logical relationship of each component in the thermal power plant system, and comprehensively considering the working status of the outgoing line interval, boiler, steam turbine generator, main transformer, and the output influence of the fan and coal feeder.

[0013] Further optimization is performed by calculating a certain earthquake intensity parameter IM based on the seismic vulnerability curve, reliability block diagram model and residual function state function of each component in the thermal power plant system through the Monte Carlo simulation method. i The failure probability sample points of different residual function states of the thermal power plant system include the following steps:

[0014] Setting the number of repetitions of the Monte Carlo simulation method and determining the residual function status of the thermal power plant system in each simulation;

[0015] According to the residual function state of the thermal power plant system in each simulation, the failure probability of different residual function states of the thermal power plant system is determined.

[0016] Further preferably, the method for determining the residual functional state of the thermal power plant system in each simulation is as follows:

[0017] The seismic fragility curves of each component in the thermal power plant system are used to obtain the ground motion intensity parameters IM of each component. i The probability of failure under

[0018] The working status of each component is evaluated, wherein the working status evaluation process of a single component is as follows: In the reliability block diagram model of the thermal power plant system, a uniformly distributed random number between 0 and 1 is generated for each component. For each component, under a given earthquake intensity parameter IM i If the random number is less than or equal to the failure probability, the component is considered to be failed and outputs "0". Otherwise, if the random number is greater than the failure probability, the component is considered to be working normally and outputs "1".

[0019] The working status of the entire thermal power plant system is analyzed by using the working status of each component and the established reliability block diagram model of the thermal power plant system. Combined with the residual function state function of the entire thermal power plant system, the residual function state of the thermal power plant system in this Monte Carlo simulation is obtained.

[0020] Further preferably, the method of obtaining the seismic vulnerability curves of the thermal power plant system in different residual function states by performing nonlinear curve fitting on the failure probability sample points is as follows:

[0021] According to the calculated failure probability sample points, the nonlinear curve fitting is performed using the formula P(PGA=x)=Φ(ln(x / μ) / β) to obtain the seismic vulnerability curves of the thermal power plant system with different residual function states.

[0022] The invention provides a method for assessing the seismic vulnerability of a thermal power plant system based on a reliability block diagram and Monte Carlo simulation. The method takes into account the physical and functional connectivity between various devices and buildings (structures), establishes a reliability block diagram model of the thermal power plant system, defines a residual functional state function of the thermal power plant system, and implements seismic vulnerability analysis at the system level of the thermal power plant based on the seismic vulnerability curve at the component level within the thermal power plant system through the Monte Carlo simulation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0024] Figure 1 Reliability block diagram model of a typical thermal power plant

[0025] Figure 2 It is the structural diagram of the section 1 of the reliability block diagram of the thermal power plant;

[0026] Figure 3 It is the structural diagram of section 2 of the reliability block diagram of a thermal power plant;

[0027] Figure 4 Flowchart for evaluating the working condition of individual components;

[0028] Figure 5 Monte Carlo simulation flow chart for seismic vulnerability assessment of thermal power plants;

[0029] Figure 6 This is a seismic vulnerability curve for a typical thermal power plant system. DETAILED DESCRIPTION

[0030] The present invention will be further explained below in conjunction with specific implementation schemes, but the present invention is not limited thereto.

[0031] A thermal power plant is a large and complex system. Too many components and too many system function states will cause a surge in the amount of calculation required for analytical operations. Therefore, Monte Carlo simulation is more flexible and convenient for the study of thermal power plants. Monte Carlo simulation is simple to calculate and has a certain error, but its calculation error is inversely proportional to the square root of the number of tests. The error can be reduced to an acceptable level by increasing the number of tests.

[0032] A thermal power plant consists of multiple subsystems, such as a steam-water system, a combustion system, and an electrical system. These systems intersect and circulate with each other to form the entire system. Each subsystem contains a large number of components. In a thermal power plant, the functions and operating states of each subsystem are interrelated and affect each other. It is inappropriate to study each subsystem separately. It is necessary to break up the subsystems according to the series and parallel logical relationship between each component and study the entire thermal power generation system.

[0033] Reliability Block Diagram (RBD) is a method based on graph theory that studies the logical relationship between systems and components from the perspective of reliability. Through the arrangement of boxes and lines, the impact of failures of various components of the system on the functional characteristics of the system can be drawn. Reliability block diagrams are mainly used to analyze the reliability of the system and evaluate the impact of component failures on the overall reliability of the system. It only considers the parallel and series relationships between components, but not the sequential relationship between components. It only considers the relationship between components from the perspective of reliability.

[0034] The invention provides a method for assessing the seismic vulnerability of a thermal power plant system based on a reliability block diagram and Monte Carlo simulation, comprising:

[0035] S1: Establish a reliability block diagram model based on the physical and functional logical relationships of each component in the thermal power plant system;

[0036] Among them, the reliability block diagram model is composed of two most basic structural types: series structure and parallel structure: when each unit in the series structure works normally, the series structure can work normally; when at least one unit in the parallel structure works normally, the parallel structure can work normally; the components in the thermal power plant system express the logical relationship of the entire thermal power plant system through different combinations of the two basic structural forms;

[0037] The subsystems in the thermal power plant are broken down, and the equipment and building structures in each subsystem of the thermal power plant are used as nodes of the reliability block diagram model. Only the parallel and series relationships between the nodes are considered, but the order relationship between the nodes is not considered. The relationship between the nodes is only considered from the perspective of reliability.

[0038] S2: define a residual function state function of the thermal power plant system, wherein the value range of the residual function state function is between 0 and 1, and is used to characterize different damage states of the thermal power plant system after an earthquake;

[0039] Among them, based on the reliability block diagram of the thermal power plant system, the logical relationship of each component in the thermal power plant system is considered, the working status of the outgoing line interval, boiler, steam turbine generator, main transformer, and the output influence of the fan and coal feeder are comprehensively considered, and the residual function state function of the thermal power plant system is defined from the core function (power generation capacity) of the thermal power plant. Among them, the value range of the residual function state function is the set of different post-earthquake damage states of the thermal power plant system;

[0040] S3: Determine the parameters in the seismic vulnerability curve of each component in the thermal power plant system, wherein the parameters include μ and β, and the seismic vulnerability curve of each component obeys a logarithmic normal distribution with a logarithmic median of μ and a logarithmic standard deviation of β, wherein the seismic vulnerability parameters are used as a basis for determining the post-earthquake state of each component;

[0041] In the process of determining the parameters in the seismic vulnerability curve of each component in the thermal power plant system, it is assumed that the operating state of each component is independent of other components, and the operating state of each component only considers success or failure; the seismic vulnerability curve of each component in the thermal power plant obeys the logarithmic normal distribution with a logarithmic median of μ and a logarithmic standard deviation of β, where the logarithmic median of μ and the logarithmic standard deviation of β are called the seismic vulnerability parameters of the component;

[0042] Through the seismic fragility curves of each component, the failure probability of each component under different earthquake motion intensities can be obtained;

[0043] S4: Based on the seismic vulnerability curves, reliability block diagram models and residual functional state functions of each component in the thermal power plant system, the failure probability sample points of different residual functional states of the thermal power plant system under different seismic motion intensity parameters are calculated by the Monte Carlo simulation method, and the seismic vulnerability curves of different residual functional states of the thermal power plant system are obtained by performing nonlinear curve fitting on the failure probability sample points.

[0044] Among them, based on the seismic vulnerability curves, reliability block diagram models and residual functional state functions of each component in the thermal power plant system, a certain ground motion intensity parameter IM is calculated by Monte Carlo simulation method. i The failure probability sample points of different residual function states of the thermal power plant system include the following steps:

[0045] S41: setting the number of repetitions of the Monte Carlo simulation method and determining the residual function state of the thermal power plant system in each simulation;

[0046] The method for determining the residual function state of the thermal power plant system in each simulation is as follows:

[0047] S411: Obtain the ground motion intensity parameter IM of each component in the thermal power plant system through the seismic vulnerability curve of each component in the thermal power plant system i The probability of failure under

[0048] S412: Evaluate the working status of each component, wherein the working status evaluation process of a single component is as follows: In the reliability block diagram model of the thermal power plant system, generate a uniformly distributed random number between 0 and 1 for each component, and for each component, under a given earthquake intensity parameter IM i If the random number is less than or equal to the failure probability, the component is considered to be failed and outputs "0". Otherwise, if the random number is greater than the failure probability, the component is considered to be working normally and outputs "1".

[0049] S413: Analyze the working state of the entire thermal power plant system using the working state of each component and the established thermal power plant system reliability block diagram model, and combine the residual function state function of the entire thermal power plant system to obtain the residual function state of the thermal power plant system in this Monte Carlo simulation, that is, obtain the damage state of the thermal power plant system in a single Monte Carlo simulation;

[0050] S42: Determine the failure probability of different residual functional states of the thermal power plant system according to the residual functional state of the thermal power plant system in each simulation.

[0051] The method for obtaining the seismic vulnerability curves of the thermal power plant system in different residual function states by performing nonlinear curve fitting on the failure probability sample points is as follows:

[0052] According to the calculated failure probability sample points, the nonlinear curve fitting is performed using the formula P(PGA=x)=Φ(ln(x / μ) / β) to obtain the seismic vulnerability curves of the thermal power plant system with different residual function states.

[0053] This method of seismic vulnerability assessment of thermal power plant system based on reliability block diagram and Monte Carlo simulation defines the residual function state function of thermal power plant system and establishes a complete system reliability block diagram (RBD) model, which can clearly describe the physical and functional logical relationship between various components in the thermal power plant, covering various mechanical equipment, electrical equipment and buildings (structures). Based on the Monte Carlo simulation method of reliability block diagram (RBD), combined with the seismic vulnerability parameters of components, the quantitative assessment of the post-earthquake damage state of the thermal power plant can be realized, and the seismic vulnerability curves of the thermal power plant system under different residual function states can be obtained. The median and logarithmic standard deviation of the seismic vulnerability function under different residual function states of the system can also be obtained by fitting.

[0054] Example

[0055] Taking a typical coal-fired power plant with two 150 MW air-cooled pure condensing steam turbine generator sets and two 480 t / h circulating fluidized bed boilers as an example, the reliability block diagram (RBD) model of the thermal power plant is established. Figure 1 shown.

[0056] The thermal power plant has three coal supply methods: coal storage in the coal yard, coal delivered by train, and coal delivered by truck. Assumptions: 1) Regardless of the coal supply method, sufficient fuel resources can be provided in a timely manner; 2) The operating status of each component is independent of other components; 3) The operating status of each component only considers success or failure, and can be described by probability.

[0057] This system simplifies the coal unloading in the coal transportation system, and integrates it into three components: coal storage in the coal yard, coal from trains, and coal from cars. Each component integrates all the functions of this process. The coal conveyor is a double-channel belt conveyor, which can be operated in one channel or in two channels at the same time. The output of each belt conveyor is not less than 150% of the total coal consumption at the maximum continuous evaporation of the boiler in the whole plant, that is, one belt operation can meet the realization of the complete functions of the thermal power plant, and the belt conveyor component integrates a series of functions such as transfer, coal crushing, screening, and iron removal during coal transportation. Both belt conveyor equipments are set in the same coal transportation building, so the two parallel belt conveyors are connected in series with the coal transportation building. The coal feeding method adopts the front-of-furnace coal feeding. Each coal bunker corresponds to two weighing scraper coal feeders. The coal feeding amount of each coal feeder can meet 35% of the coal amount required for a boiler to operate at full load. The coal feeding amount of any three coal feeders can meet the corresponding full load operation of a boiler. Under normal circumstances, each coal feeder runs with 25% load of a single boiler. The coal is sent to the coal hopper in the coal bunker through the belt conveyor, and then transported to the furnace of the boiler through the coal hopper and the coal feeder. Two coal hoppers are set for each boiler, and two coal feeders are set for each coal hopper. The coal transported by the two belts can enter any coal hopper. The primary and secondary fans of the air supply system are configured separately. Each boiler is equipped with 2 primary fans and 2 secondary fans. When selecting the fan, a 20% margin is reserved for the air volume and air pressure of the fan. When 1 primary fan and 1 secondary fan are in operation, the corresponding boiler can operate at less than full load.

[0058] The flue gas generated by the combustion of coal in the boiler passes through the denitrification, dust collector, induced draft fan, flue, and then merges into the desulfurization system and is discharged into the atmosphere through the chimney. The slag after combustion is discharged through the slag removal system. The ash discharged by the flue gas through the dust collector enters the ash storage through the ash pipe. Each boiler corresponds to a dust collector, two induced draft fans, and a set of slag removal system. When selecting the induced draft fan, a 20% margin is reserved for the fan's air volume and air pressure. When one induced draft fan is running, the corresponding boiler can operate at less than full load. Two boilers are equipped with one desulfurization system, one desulfurization system, one chimney, and two shared ash storages.

[0059] The steam generated by boiler combustion enters the steam turbine through the main steam pipe, causing the steam turbine to expand and do work. After doing work, the exhaust gas of the steam turbine enters the condenser and is condensed into water. The condensed water passes through the condensate pump, low-pressure heater, deaerator, feed water pump, and high-pressure heater to increase the pressure, temperature, and deoxygenate the feed water before entering the boiler, forming a closed cycle of steam and water. In this closed cycle, there will inevitably be steam and water losses, which will be replenished by the chemical desalted water system. The heat released when the turbine exhaust gas condenses in the condenser is taken away by the cooling water system (circulating water pump + cooling tower). The main steam pipe is connected by a mother pipe, so the 1# main steam pipe and the 2# main steam pipe are connected in parallel and then in series in the system. Each steam turbine corresponds to a condenser, so each condenser is connected in series with the corresponding steam turbine. Each steam turbine corresponds to 2 condensate pumps, 2 low-pressure heaters, 2 feed water pumps, and 2 circulating water pumps, one for use and one for backup, so they are all connected in parallel and then in series with the corresponding steam turbine. Each condensate pump is connected in series with its corresponding shaft seal heater, then in parallel, and then in series with the corresponding steam turbine. There are 2 cooling towers in the cooling water system, which are shared by the entire system. They are connected in parallel and then in series in the entire system. The deaerator is connected by a mother pipe, and the two deaerators are connected in parallel and then in series in the system.

[0060] The electric energy generated by the steam turbine generator is stepped up by the main transformer and then sent out through the high-voltage power distribution device. Each steam turbine generator corresponds to a main transformer, and then connected to the 1# outgoing line bay and the 2# outgoing line bay through the busbar. The main transformer and its corresponding steam turbine generator are connected in series and then in parallel, and then in series in the entire system. Finally, the 1# outgoing line bay and the 2# outgoing line bay serve as the two outputs of the entire system.

[0061] The logical relationship of the entire system is thus fully represented in the reliability block diagram.

[0062] As a complex system, a thermal power plant consists of multiple interconnected equipment and buildings (structures), which work together to realize the power generation function. When evaluating the seismic vulnerability of a thermal power plant, the first step is to clearly define its function. Unlike the analysis of the seismic vulnerability of building structures, the seismic vulnerability analysis of a thermal power plant cannot only use the damage of the components as an evaluation indicator, but should take whether the power generation function can be maintained as the main indicator. Therefore, the definition of function is crucial for the seismic vulnerability assessment of thermal power plants.

[0063] Due to the complexity of thermal power plants, the functional definition needs to be more detailed. The functional definition of thermal power plants may vary depending on their system models, so the evaluation results will also be different. When conducting seismic performance evaluation, it is necessary to comprehensively consider the overall functional performance and power generation capacity of the system to ensure that the system can maintain its key functions when an earthquake occurs. Therefore, the functional definition of thermal power plants needs to fully consider their complexity and particularity.

[0064] The remaining function state function of a thermal power plant is defined based on the core function (power generation function) of the thermal power plant, taking the following aspects into consideration:

[0065] (1) The entire system is a complex system with multiple outputs. The ratio of the number of outputs to the total number of system outputs can be used as the definition of the system function.

[0066] (2) Figure 2 As shown in the figure, the first section of the reliability block diagram of the thermal power plant consists of two parallel paths, and the failure of any one of the paths will cause a boiler to completely lose its contribution to the power generation function of the entire power plant. Therefore, the ratio of the number of paths of the two parallel main paths in section 1 to the total number of paths is taken as part of the system function definition;

[0067] (3) Figure 3 As shown in the figure, the second section of the reliability block diagram of the thermal power plant consists of two parallel paths, and the failure of any one of the paths will cause a steam turbine generator and its corresponding main transformer to completely lose their contribution to the power generation function of the entire power plant. Therefore, the ratio of the number of paths of the two parallel main paths in section 2 to the total number of paths is taken as part of the system function definition;

[0068] (4) The output of one deaerator is required for the operation of one unit. Two deaerators are set for the operation of two units. Therefore, the number of deaerators in normal operation affects the power generation capacity of the entire thermal power plant. Consider taking the ratio of the number of deaerators in normal operation to the total number of deaerators as part of the system function definition;

[0069] (5) The coal supply of a coal feeder can meet 35% of the coal supply required for a boiler to operate at full load. When selecting the primary fan, secondary fan and induced draft fan, a 20% margin is reserved for the fan air volume and air pressure. Therefore, when defining the system function, the impact of the single output of the coal feeder and the three types of fans on the power generation function needs to be considered;

[0070] Based on the above five factors affecting the function of thermal power plants, the residual function state function F of thermal power plants is defined. ratio :

[0071]

[0072] Among them, N 出线间隔 Represents the number of successes in the two occurrence intervals of the output of the entire thermal power plant system, N i号区段 Indicates the number of successful branches in the two parallel branches in section i, i = 1 or 2; N 除氧器 Indicates the number of deaerators that do not fail, N iXX#给煤机 Indicates the number of coal feeders numbered iXX# that are not inoperative, i = 1 or 2; N iX#一次风机Indicates the number of primary fans numbered iX# that do not fail, i = 1 or 2; N iX#二次风机 Indicates the number of secondary fans numbered iX# that are not failed, i = 1 or 2; N iX#引风机 Indicates the number of induced draft fans numbered iX# that have not failed, i = 1 or 2;

[0073] Among them, when 0.175N iXX#给煤机 ≥0.5, 0.175N iXX#给煤机 Take 0.5, i = 1 or 2;

[0074] 0.3N iX#一次风机 ≥0.5, 0.3N iX#一次风机 Take 0.5, i = 1 or 2;

[0075] 0.3N iX#二次风机 ≥0.5, 0.3N iX#二次风机 Take 0.5, i = 1 or 2;

[0076] 0.3N iX#引风机 ≥0.5, 0.3N iX#引风机 Take 0.5, i=1 or 2.

[0077] Determine the peak ground acceleration (PGA) as the seismic intensity parameter, and determine the PGA value range of 0.01 to 0.6g, with a step size of 0.01g;

[0078] Determine the vulnerability parameters of the components of the thermal power plant system (Table 1);

[0079] Table 1

[0080]

[0081] Start the Monte Carlo simulation cycle for the seismic vulnerability assessment of thermal power plants. In a single Monte Carlo simulation, first, determine the input ground motion intensity parameter IM i , the seismic fragility curve of the defined equipment or building is used to obtain the ground motion intensity parameter IM of the component. i After that, the working status of each component is evaluated and recorded. The working status evaluation process of a single component is as follows: Figure 4 As shown in the system reliability block diagram model, a uniformly distributed random number between 0 and 1 is generated for each component. For each component, under a given earthquake intensity parameter IM iIf the random number is less than or equal to the failure probability, the component is judged to be failed and output "0". Otherwise, if the random number is greater than the failure probability, the component is judged to be working normally and output "1". Then, the working state of the entire thermal power plant system is obtained by analyzing the working state of each component and the established thermal power plant reliability block diagram model, and the residual function state function of the thermal power plant system is combined to obtain the residual function state F of the thermal power plant system in this Monte Carlo simulation. ratio , and record it.

[0082] For each IM i , repeat the above simulation process n times, and record the working status of each component in the thermal power plant and the residual function status of the thermal power plant system in each simulation, count the frequency k of failure of each residual function status of the power plant, and calculate the corresponding failure probability In this embodiment, n=1000; according to the calculated failure probability sample points, the seismic vulnerability curve of the thermal power plant system is completed by performing nonlinear curve fitting using the formula P(PGA=x)=Φ(ln(x / μ) / β), as shown in FIG. Figure 6 As shown, the Monte Carlo simulation cycle for seismic vulnerability analysis of thermal power plants is completed. Figure 5 The process of Monte Carlo simulation is shown in Figure 2.

[0083] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for assessing seismic vulnerability of a thermal power plant system based on reliability block diagram and Monte Carlo simulation, characterized in that: include: Establish a reliability block diagram model based on the physical and functional logical relationships of each component in the thermal power plant system; Define a residual function state function of a thermal power plant system, wherein the value of the residual function state function ranges from 0 to 1; Determine the parameters in the seismic vulnerability curve of each component in the thermal power plant system, wherein the parameters include μ and β, and the seismic vulnerability curve of each component obeys a logarithmic normal distribution with a logarithmic median of μ and a logarithmic standard deviation of β; Based on the seismic vulnerability curves, reliability block diagram models and residual functional state functions of various components in the thermal power plant system, the failure probability sample points of different residual functional states of the thermal power plant system under different seismic motion intensity parameters are calculated by the Monte Carlo simulation method, and the seismic vulnerability curves of different residual functional states of the thermal power plant system are obtained by performing nonlinear curve fitting on the failure probability sample points.

2. The method for seismic vulnerability assessment of a thermal power plant system based on reliability block diagram and Monte Carlo simulation according to claim 1, characterized in that: The reliability block diagram model is composed of two most basic structural types, namely, a series structure and a parallel structure. The series structure can only work normally when each unit in the series structure works normally; the parallel structure can work normally when at least one unit in the parallel structure works normally. The components in the thermal power plant system express the logical relationship of the entire thermal power plant system through different combinations of the two basic structural forms. The equipment and structures in the thermal power plant system serve as nodes of the reliability block diagram model.

3. The method for seismic vulnerability assessment of a thermal power plant system based on reliability block diagram and Monte Carlo simulation according to claim 1 is characterized in that: When defining the residual function state function of the thermal power plant system, the reliability block diagram of the thermal power plant system is used as the basis, the logical relationship between the various components in the thermal power plant system is considered, and the working conditions of the outgoing line interval, boiler, steam turbine generator, main transformer, and the output influence of the fan and coal feeder are comprehensively considered.

4. The method for seismic vulnerability assessment of a thermal power plant system based on reliability block diagram and Monte Carlo simulation according to claim 1 is characterized in that: Based on the seismic vulnerability curves, reliability block diagram models and residual functional state functions of each component in the thermal power plant system, a certain ground motion intensity parameter IM is calculated by Monte Carlo simulation method. i The failure probability sample points of different residual function states of the thermal power plant system include the following steps: Setting the number of repetitions of the Monte Carlo simulation method and determining the residual function status of the thermal power plant system in each simulation; According to the residual function state of the thermal power plant system in each simulation, the failure probability of different residual function states of the thermal power plant system is determined.

5. The method for seismic vulnerability assessment of a thermal power plant system based on reliability block diagram and Monte Carlo simulation according to claim 4 is characterized in that: The method for determining the residual function status of the thermal power plant system in each simulation is as follows: The seismic fragility curves of each component in the thermal power plant system are used to obtain the ground motion intensity parameters IM of each component. i The probability of failure under The working status of each component is evaluated, wherein the working status evaluation process of a single component is as follows: In the reliability block diagram model of the thermal power plant system, a uniformly distributed random number between 0 and 1 is generated for each component. For each component, under a given earthquake intensity parameter IM i If the random number is less than or equal to the failure probability, the component is considered to be failed and output "0". Otherwise, if the random number is greater than the failure probability, the component is considered to be working normally and output "1". The working status of the entire thermal power plant system is analyzed by using the working status of each component and the established reliability block diagram model of the thermal power plant system. Combined with the residual function state function of the entire thermal power plant system, the residual function state of the thermal power plant system in this Monte Carlo simulation is obtained.

6. The method for seismic vulnerability assessment of a thermal power plant system based on reliability block diagram and Monte Carlo simulation according to claim 1, characterized in that: The method of obtaining the seismic vulnerability curves of different residual function states of the thermal power plant system by performing nonlinear curve fitting on the failure probability sample points is as follows: According to the calculated failure probability sample points, the nonlinear curve fitting is performed using the formula P(PGA=x)=Φ(ln(x / μ) / β) to obtain the seismic vulnerability curves of the thermal power plant system with different residual function states.

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