Deep peak-shaving thermal power generating unit steam turbine considering heat supply working condition and speed regulating system simulation modeling method of deep peak-shaving thermal power generating unit steam turbine

Abstract

The invention relates to a deep peak regulation thermal power generating unit steam turbine considering a heat supply working condition and a simulation modeling method of a speed regulation system of the deep peak regulation thermal power generating unit steam turbine, and belongs to the technical field of power system operation control. The method comprises the steps that a system model composed of a speed regulator module, an executing mechanism module, a steam turbine module and a boiler module is constructed, the speed regulator module processes power and rotating speed deviation and outputs a control valve opening degree instruction, and the steam turbine module receives the control valve opening degree and main steam pressure output by a boiler at the same time to calculate mechanical power; establishing a steam turbine module model considering the heat supply working condition, wherein the steam turbine module model comprises a heat supply steam extraction module; performing balance calculation on model parameter assignment and model variable initialization; setting scenes such as set frequency given disturbance, set power disturbance and steam extraction disturbance, and verifying simulation characteristics under different peak shaving depths in a step mode; simulation characteristics are verified under different working conditions, and the deep peak regulation thermal power generating unit steam turbine and the speed regulation system thereof can be efficiently modeled with the consideration of accuracy and accuracy.

Description

Technical Field

[0001] This invention belongs to the field of power system operation and control technology, specifically relating to a simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system that considers heating conditions. Background Technology

[0002] With the expansion of new energy grid connection, thermal power units, due to their large installed capacity and stable frequency response, remain a crucial power source for grid frequency regulation and peak shaving to address issues such as large system power fluctuations caused by their randomness and volatility. However, simulation models and parameters of thermal power units based on typical operating conditions in the power system are difficult to apply to deep peak shaving conditions. Therefore, there is an urgent need to establish a model that can accurately reflect the operating characteristics of units under deep peak shaving conditions.

[0003] Typical models of thermal power units fail to adequately consider the nonlinear relationships in the turbine and its speed control system, instead resorting to simple linear fitting. This leads to a significant increase in the impact of neglected nonlinear relationships on the unit's response when the peak-shaving depth varies widely. The flow characteristics of turbine valves and the main steam pressure have a certain influence on the power response of thermal power units participating in primary frequency regulation. Considering the nonlinear characteristics of valve flow, a model for the unit's participation in primary frequency regulation is established. Through analysis and optimization of the turbine valve flow characteristics, the simulation response of the unit's primary frequency regulation becomes more accurate. Power system simulation analysis lacks simulation models that consider the heating conditions of thermal power units. There is an urgent need to propose a simulation modeling method for the turbine and its speed control system of deep peak-shaving thermal power units that considers the heating conditions, and to establish a dynamic model for thermal power units participating in primary frequency regulation under deep peak-shaving conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a simulation modeling method for steam turbines and their speed control systems in deep peak-shaving thermal power units that takes into account heating conditions.

[0005] To achieve the above objectives, the technical solution of the present invention is: a simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, comprising the following steps:

[0006] S1. Considering the deep peak-shaving thermal power unit turbine and its speed control system under heating conditions, a system model is constructed consisting of a governor module, an actuator module, a turbine module, and a boiler module. The power deviation and speed deviation are input to the governor module. The valve opening command output by the governor module is used as the input to the actuator module. The output of the actuator module controls the valve opening. The main steam pressure output by the boiler module and the valve opening are used as inputs to the turbine module. The turbine module outputs mechanical power.

[0007] S2. Establish a turbine module model that considers the heating operation condition. This model includes a turbine heating extraction module.

[0008] S3. Assign values ​​to the model parameters and perform model variable initialization and balance calculations;

[0009] S4. Set up scenarios for unit frequency setpoint disturbance, unit power disturbance, and extraction steam flow disturbance;

[0010] S5. Verify the simulation characteristics under different working conditions and output the model simulation results.

[0011] Furthermore, the speed governor module includes valve position control and coordinated control modes. The coordinated control mode obtains the valve opening setpoint based on the difference between the unit speed setpoint and the unit speed, and the difference between the power setpoint and the unit active power, through the action of a proportional-integral-derivative controller and power feedforward control. The speed governor module also considers the primary frequency regulation rate limit and the upper and lower limits of the primary frequency regulation amplitude under different peak regulation depths.

[0012] Furthermore, the turbine module considers the impact of changes in the main steam pressure output from the boiler module on the input steam flow rate, and establishes a nonlinear relationship between mechanical power, valve opening, and main steam pressure; the main steam flow rate Q entering the turbine... T and per-unit value of steam flow The expressions are as follows:

[0013]

[0014] Among them, Q sn and These represent the main steam flow rate and main steam pressure under rated operating conditions, respectively, P T Main steam pressure, Let P be the valve opening function. GV This refers to the opening degree of the damper.

[0015] Furthermore, the nonlinear relationship is established by creating a piecewise linear fitting relationship based on different peak-shaving operating points to generate the valve opening P. GV Main steam pressure P T The nonlinear relationship between the input steam flow rate and the output steam flow rate is used to achieve an approximate piecewise linear fit of the nonlinear relationship within the unit output range [P]. gi , P gj Within [ ], the linear fitting expression is:

[0016]

[0017] Among them, P gj and P gi These correspond to the upper and lower power values ​​of the unit's output range, respectively; a0 and a1 are fitting coefficients.

[0018] Furthermore, when considering the heating operation, a steam turbine heating extraction module model is established, including the extraction volume component, the butterfly valve hydraulic actuator component, and the proportional-integral controller component. The unit also maintains a thermal balance relationship under heating conditions.

[0019]

[0020] Among them, Q IP Q is the steam flow rate at the outlet of the intermediate-pressure cylinder; LP Q represents the low-pressure inlet steam flow rate; ES This refers to the steam extraction flow rate for heating.

[0021] Furthermore, the variable initialization equilibrium calculation is based on differential equations. For a typical first-order differential equation:

[0022]

[0023] Where x2 is the input quantity; x1 is the feedback quantity;

[0024] The transfer function obtained by performing the Laplace transform is:

[0025]

[0026] Initially, and again after the transient process under disturbance conditions, upon entering a new steady state, let the right side of the equation... The result is equal to 0, such that x2 = x1.

[0027] Furthermore, the generator frequency and power disturbances were set for the governor module, and the extraction steam flow command disturbance scenario was set for the turbine module. The disturbance setting method was step disturbance. The simulation characteristics were verified under different operating conditions, and the simulation results of the model were output.

[0028] Furthermore, the turbine module incorporates a natural overshoot coefficient for the high-pressure cylinder power. To reflect the over-adjustment characteristics of the high-pressure cylinder output during dynamic processes, and the turbine module model includes the power coefficients of the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder, satisfying... .

[0029] The present invention also provides a simulation modeling system for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, including a memory, a processor, and computer program instructions stored in the memory and executable by the processor. When the processor executes the computer program instructions, it can implement the steps of the method described above.

[0030] The present invention also provides a computer-readable storage medium having stored thereon computer program instructions that can be executed by a processor, wherein when the processor executes the computer program instructions, it can implement the steps of the method described above.

[0031] Compared with the prior art, the present invention has the following beneficial effects: Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 shows the simulation modeling method of steam turbine and its speed control system of deep peak-shaving thermal power unit considering heating conditions;

[0034] Figure 2 is a block diagram of the steam turbine and its speed control system;

[0035] Figure 3 This is a speed controller module model;

[0036] Figure 4 For the actuator module model;

[0037] Figure 5 This is a steam turbine module model;

[0038] Figure 6 This is a typical unit valve flow non-characteristic curve;

[0039] Figure 7 The following are turbine module models with heating operation: (a) turbine module model with heating operation, (b) turbine heating extraction module model;

[0040] Figure 8 Boiler module model with control: (a) Boiler model, (b) Boiler main control command, (c) Sliding pressure curve of typical unit;

[0041] Figure 9 Simulation results for a step change in power setpoint: (a) change in valve opening, (b) change in main steam pressure, (c) change in unit output mechanical power;

[0042] Figure 10 Simulation results for a step change in the steam extraction flow rate command for heating: (a) Change in unit output mechanical power, (b) Change in steam extraction flow rate. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] like Figure 1 As shown, this invention provides a simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, including the following steps:

[0045] S1. Considering the deep peak-shaving thermal power unit turbine and its speed control system under heating conditions, a system model is constructed consisting of a governor module, an actuator module, a turbine module, and a boiler module. The power deviation and speed deviation are input to the governor module. The valve opening command output by the governor module is used as the input to the actuator module. The output of the actuator module controls the valve opening. The main steam pressure output by the boiler module and the valve opening are used as inputs to the turbine module. The turbine module outputs mechanical power.

[0046] S2. Establish a turbine module model that considers the heating operation condition. This model includes a turbine heating extraction module.

[0047] S3. Assign values ​​to the model parameters and perform model variable initialization and balance calculations;

[0048] S4. Set up scenarios for unit frequency setpoint disturbance, unit power disturbance, and extraction steam flow disturbance;

[0049] S5. Verify the simulation characteristics under different working conditions and output the model simulation results.

[0050] 1. Steam turbine and its speed control system model

[0051] The speed change signal caused by load disturbance is input to the governor, amplified by the hydraulic actuator, and used to control the opening of the regulating valve. The mathematical model of the turbine and speed control system consists of three parts: the governor, the actuator, and the turbine module model. Its overall structural block diagram is shown below. Figure 2 As shown in the diagram. The setpoint and controller are both implemented within the computer. During operation, the setpoint and its rate of change, including power and speed, are provided manually and automatically. After the setpoint is determined, the deviation is sent to the regulator for calculation based on the system feedback signal, and then a valve opening command is issued to the actuator.

[0052] 1.1 Speed ​​Regulator Model

[0053] The speed governor input signal is the rotational speed. and given speed The power setpoint and power feedback are processed by a PID controller as a correction unit, outputting the valve opening command. The governor model is then as follows: Figure 3 As shown. Figure 3 The control system is divided into two types: power control and valve control. Rotational speed and given speed Deviation; , and These are the proportional, derivative, and integral multipliers of the PID controller, respectively; P CV This is the valve opening command; The power setpoint; The active power of the generator unit; This is the amplification factor for the rotational speed deviation; T is the load control feedforward coefficient; R1 and T R2 T1 is the time constant of the input signal filtering stage; T1~T4 are the time constants of the delay stage.

[0054] 1.2 Actuator Model

[0055] The actuator includes an electro-hydraulic converter and a hydraulic actuator. The actuator amplifies the control signal from the governor and converts it into the valve opening, controlling the steam flow into the turbine. The actuator model is as follows: Figure 4 As shown. Figure 4 middle, , , These represent the proportional, integral, and differential factors of the integrated amplification module. The integrated amplification module typically consists of a proportional or proportional-integral component. and The upper and lower limits are output for the comprehensive amplification stage; , These are the overspeed opening and overspeed closing coefficients, respectively. and These are the opening and closing time constants of the hydraulic actuator, respectively. The time constant of the hydraulic actuator stroke feedback loop is typically taken as 0.02s; P max and P min is the upper and lower limits of the turbine power output; T is the time constant of the delay element.

[0056] 1.3 Steam Turbine Module Model

[0057] For intermediate reheat units, when the speed control system activates, such as when the control valve suddenly opens wide, the steam inlet pressure to the high-pressure cylinder rises rapidly. Due to the large intermediate volume, the exhaust pressure to the high-pressure cylinder can only rise slowly, causing a change in the steam pressure difference between the inlet and outlet of the high-pressure cylinder. This results in the output proportional coefficient of the high-pressure cylinder during the dynamic process being greater than the proportional coefficient during steady-state operation. To reflect this physical phenomenon, a natural overshoot coefficient for the high-pressure cylinder power is introduced. The prime mover model is as follows: Figure 5 As shown. Figure 5 middle, , , The power coefficients of the high, medium, and low-pressure cylinders of the steam turbine are given. ; , , P represents the volumetric time constant for high-pressure steam, reheat steam, and low-pressure steam. T Main steam pressure; This represents the natural overshoot coefficient for the high-pressure cylinder power. A typical unit's valve flow non-characteristic curve is shown below. Figure 6 As shown.

[0058] Based on the peak-shaving operation points at different depths, a piecewise linear fitting relationship is established to generate the valve opening P. GV Main steam pressure P T The nonlinear relationship between flow rate and output is used to achieve an approximate piecewise linear fit of the nonlinear relationship. Within the unit output range [P]... gi , P gj f i (P GV The linear fitting expression is:

[0059] (1)

[0060] In the formula, a0 and a1 are fitting coefficients.

[0061] The turbine module considers the impact of changes in the main steam pressure output from the boiler module on the steam flow rate input to the turbine module. The main steam flow rate Q entering the turbine is... T and per-unit value of steam flow The expressions are as follows:

[0062] (2)

[0063] Among them, Q sn and These are the main steam flow rate and main steam pressure under rated operating conditions, respectively.

[0064] 1.4 Steam Turbine Module Model Considering Heating Conditions

[0065] Steam turbine module model including heating operation, such as Figure 7 As shown in (a), the steam turbine heating extraction module model is as follows. Figure 7 As shown in (b). Figure 7 (b) includes the extraction steam volume stage, the butterfly valve hydraulic actuator stage, and the proportional-integral controller stage. Q IP Q is the steam flow rate at the outlet of the intermediate-pressure cylinder; LP Q represents the low-pressure inlet steam flow rate; ES This is a command for the steam extraction flow rate for heating; T es T is the time constant of the steam extraction volume for heating; dv K is the time constant of the butterfly valve hydraulic actuator. e This refers to the extraction steam pressure inequality rate.

[0066] The following heat balance relationship exists for the heating unit:

[0067] (3)

[0068] Without considering heating conditions Figure 7 (a) The heating steam extraction module is replaced by a proportional element with a proportional coefficient of 1.

[0069] 1.5 Boiler Model

[0070] ① Fuel lag

[0071] After the combustion adjustment command is issued, due to the response characteristics of equipment such as the coal mill, a physical process occurs where fuel lags behind the fuel command. After passing through the pulverizing system, the combustion and heat transfer process in the furnace can be simplified to a first-order inertial element. The input is the fuel command, and the output is the fuel combustion power. The transfer function of the fuel lag element is:

[0072] (4)

[0073] In the formula, τ is the combustion lag time constant; T FL This is the fuel response time constant in the fuel lag process.

[0074] ② Water-cooled wall stage

[0075] The heat absorption of a water-cooled wall can be described by a first-order inertial element, with the input being the fuel combustion power and the output being the power absorbed by the water-cooled wall:

[0076] (5)

[0077] In the formula, T WF This is the time constant for heat absorption in the water-cooled wall process.

[0078] ③ Cargo compartment volume section

[0079] After the fuel releases chemical energy, it is transferred to the working fluid through the water-cooled walls, where liquid / vapor conversion occurs in the steam drum, continuously accumulating energy. The superheater inlet steam drum pressure P... D Reflects the hot water flow rate (m) of the water-cooled wall W Balance with superheater heat flow m, steam chamber volume time constant T D This reflects the energy stored in the steam drum. Considering the energy storage in the boiler steam drum, the energy balance equation for the steam drum is:

[0080] (6)

[0081] Performing the Laplace transform, we obtain the transfer function as follows:

[0082] (7)

[0083] ④ Superheater system

[0084] Considering only the flow characteristics of the superheater, the superheater outlet pressure is P. T The differential pressure at the superheater outlet and inlet is related to the superheater flow resistance and m. Its pressure loss is generally calculated using flow rate and can be approximated as follows:

[0085] (8)

[0086] ④ Superheater volume component

[0087] The superheater's effect on steam is a volumetric effect. (P) T As output variables, take m and m s Using the difference as an input variable, we obtain the equation for the transfer of steam energy in the pipeline:

[0088] (9)

[0089] In the formula, C SH This is the superheater volume time constant in the superheater volume system.

[0090] The transfer function is then obtained as:

[0091] (10)

[0092] Establish a boiler model under coordinated control, such as Figure 8 As shown. Figure 8 (a) considers the pulverization and combustion delay stages, and ∏ represents the signal multiplication. BD is the boiler's fuel command; K is the flow coefficient of the superheater and main steam pipeline; Q is the fuel heat; m s Main steam flow rate.

[0093] Depend on Figure 8As shown in (b), the main steam pressure is kept stable by controlling the PI controller, so that the actual main steam pressure P T Equal to the reference main steam pressure P Tref . Figure 8 The typical sliding pressure curve of the unit in (b) is as follows: Figure 8 As shown in (c).

[0094] The model parameters are assigned values ​​and the model variables are initialized for equilibrium calculation. Variable initialization is performed based on the differential equations. For example, according to equations (6) and (9), when the system reaches stability, the right side of the equation is set to 0, resulting in m = m. W =m s .

[0095] Set up scenarios for disturbances in unit frequency, unit power, and extraction steam flow; verify the characteristics under different operating conditions, and output the model simulation results.

[0096] 2. Simulation Analysis

[0097] 2.1 Simulation of Peak Shaving Conditions at Different Depths

[0098] When the unit's response frequency setpoint changes, the frequency change is translated into a change in the control valve opening command, thus adjusting the unit's power. Under deep peak-shaving operation, the unit's frequency setpoint drops from its rated value to 0.998 in approximately 37 seconds. The simulation results are as follows... Figure 9 As shown. By Figure 9 It can be seen that the opening of the power control valve shows a decreasing trend, the main steam pressure first shows an increasing trend, the maximum change in main steam pressure is about 0.01 pu, and the unit output mechanical power decreases.

[0099] 2.2 Simulation of Heating Operation

[0100] Considering the steam extraction heating condition, the initial P ref The value is set to 0.8, and the turbine extraction steam flow rate command Q is set for 50 seconds. ES The simulation results are as follows: The step value is increased from 0.2 pu to 0.5 pu. Figure 10 As shown. Steam extraction flow rate Q h After an initial adjustment process, the power output of the generator increased from 0.2 pu to 0.5 pu. With the valve opening command remaining unchanged, the change in the unit's output mechanical power showed a decreasing trend, decreasing from 0.745 pu to 0.6388 pu.

[0101] The model established based on the simulation modeling method of steam turbine and speed regulation system of deep peak-shaving thermal power unit considering heating conditions can reflect the changes in main steam pressure and its influence on the steam flow transition process, and thus reflect the influence of main steam pressure on output mechanical power. It can also reflect the changes in extraction steam flow and output mechanical power characteristics under heating conditions.

[0102] The present invention also provides a simulation modeling system for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, including a memory, a processor, and computer program instructions stored in the memory and executable by the processor. When the processor executes the computer program instructions, it can implement the steps of the method described above.

[0103] The present invention also provides a computer-readable storage medium having stored thereon computer program instructions that can be executed by a processor, wherein when the processor executes the computer program instructions, it can implement the steps of the method described above.

[0104] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, characterized in that, Includes the following steps: S1. Considering the deep peak-shaving thermal power unit turbine and its speed control system under heating conditions, a system model is constructed consisting of a governor module, an actuator module, a turbine module, and a boiler module. The power deviation and speed deviation are input to the governor module. The valve opening command output by the governor module is used as the input to the actuator module. The output of the actuator module controls the valve opening. The main steam pressure output by the boiler module and the valve opening are used as inputs to the turbine module. The turbine module outputs mechanical power. S2. Establish a turbine module model that considers the heating operation condition. This model includes a turbine heating extraction module. S3. Assign values ​​to the model parameters and perform model variable initialization and balance calculations; S4. Set up scenarios for unit frequency setpoint disturbance, unit power disturbance, and extraction steam flow disturbance; S5. Verify the simulation characteristics under different working conditions and output the model simulation results.

2. The simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, as described in claim 1, is characterized in that... The speed governor module includes valve position control and coordinated control modes. The coordinated control mode is based on the difference between the unit speed setpoint and the unit speed, and the difference between the power setpoint and the unit active power. It obtains the valve opening setpoint through the action of a proportional-integral-derivative controller and power feedforward control. The speed governor module also considers the primary frequency regulation rate limit and the upper and lower limits of the primary frequency regulation amplitude under different peak regulation depths.

3. The simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, as described in claim 1, is characterized in that... The turbine module considers the impact of changes in the main steam pressure output from the boiler module on the input steam flow rate, and establishes a nonlinear relationship between mechanical power, valve opening, and main steam pressure; the main steam flow rate Q entering the turbine... T and per-unit value of steam flow The expressions are as follows: Among them, Q sn and These represent the main steam flow rate and main steam pressure under rated operating conditions, respectively, P T Main steam pressure, Let P be the valve opening function. GV This refers to the opening degree of the damper.

4. The simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, as described in claim 3, is characterized in that... The nonlinear relationship is established by creating a piecewise linear fitting relationship based on peak shaving operation points at different depths, generating the valve opening P. GV Main steam pressure P T The nonlinear relationship between the input steam flow rate and the output steam flow rate is used to achieve an approximate piecewise linear fit of the nonlinear relationship within the unit output range [P]. gi ,P gj ]Inside, The linear fitting expression is: Among them, P gj and P gi These correspond to the upper and lower power values ​​of the unit's output range, respectively; a0 and a1 are fitting coefficients.

5. The simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, as described in claim 1, is characterized in that... When considering the heating operation, a steam turbine heating extraction module model is established, including the extraction volume component, the butterfly valve hydraulic actuator component, and the proportional-integral controller component. Furthermore, the unit maintains a heat balance relationship under heating conditions. Among them, Q IP Q is the steam flow rate at the outlet of the intermediate-pressure cylinder; LP Q represents the low-pressure inlet steam flow rate; ES This refers to the steam extraction flow rate for heating.

6. The simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, as described in claim 1, is characterized in that... The variable initialization equilibrium calculation is based on differential equations. For a typical first-order differential equation: Where x2 is the input quantity; x1 is the feedback quantity; The transfer function obtained by performing the Laplace transform is: Initially, and again after the transient process under disturbance conditions, upon entering a new steady state, let the right side of the equation... The result is equal to 0, such that x2 = x1.

7. The simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, as described in claim 1, is characterized in that... Set unit frequency and power disturbances for the governor module, and set extraction steam flow command disturbance scenarios for the turbine module; the disturbance setting method is step disturbance, verify the simulation characteristics under different operating conditions, and output the model simulation results.

8. The simulation modeling method for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, as described in claim 1, is characterized in that... The turbine module incorporates a high-pressure cylinder power natural overshoot coefficient. To reflect the over-adjustment characteristics of the high-pressure cylinder output during dynamic processes, and the turbine module model includes the power coefficients of the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder, satisfying... .

9. A simulation modeling system for a deep peak-shaving thermal power unit turbine and its speed regulation system considering heating conditions, characterized in that, It includes a memory, a processor, and computer program instructions stored in the memory and executable by the processor, which, when executed by the processor, enable the implementation of the steps of the method as described in any one of claims 1-8.

10. A computer-readable storage medium having stored thereon computer program instructions executable by a processor, wherein when the processor executes the computer program instructions, it is able to implement the steps of the method as described in any one of claims 1-8.

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