CN104158189A - Electrified railway traction power supply load modeling method based on parameter identification - Google Patents
Electrified railway traction power supply load modeling method based on parameter identification Download PDFInfo
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Abstract
The invention discloses an electrified railway traction power supply load modeling method based on parameter identification. The method includes the steps that an identification analytical expression which is combined with the characteristics of an electrified railway load locomotive in the running process to determine an electrified railway traction power supply load model is built, a typical electrified railway traction station is selected for testing, measured data of electrified railway traction power supply loads are analyzed and preprocessed, typical parameters in the electrified railway traction power supply load model are identified, and analysis validation is performed on accuracy of the electrified railway traction power supply load model by the adoption of a corresponding example. The impact effect generated when the electrified railway traction power supply loads have access to a power grid can be described better, grid planning and electrified railway development planning are supported, and the degree of coordination between grid planning and electrified railway development planning is increased.
Description
Technical Field
The invention relates to a modeling method for traction load of an electrified railway, in particular to a modeling method for traction power supply load of the electrified railway based on parameter identification.
Background
The electrified railway is a traffic mode which is mainly developed in China at present, can improve the railway transportation capacity and railway operation, and is beneficial to realizing reasonable distribution of resources, reducing the operation cost, protecting the ecological environment and the like. The "medium and long term railway network planning" approved by the State Council explicitly states that: by 2020, the total mileage of the railway in China can reach 120000km, wherein the electrified railway is 60000km, the railway electrification rate is about 60 percent, and the borne freight specific gravity is more than 80 percent. With the 6 times of speed increase of the national railway, the train speed is faster and faster, the power of a single locomotive is higher and higher, particularly, the rapid construction development of the high-speed electrified railway in recent years, such as the opening of Jingjin intercity railway, Shitai passenger special line, Guiguang passenger special line, Zhengxi passenger special line, Huning intercity railway, Huhang intercity railway and Jinghu passenger special line, and the online operation of a large number of CRH type motor train units with the speed of 250, 300 and 350 km/h.
In the large-scale construction and development of the electrified railway, on one hand, higher requirements are put forward on the electric energy quality and the power supply reliability of a public power grid; on the other hand, the traction load of the electrified railway is a typical unbalanced and impact load, has complex and changeable operation states and high randomness, can generate a large amount of harmonic waves and negative sequence current when being put into operation, and is injected into a power system through a traction substation of the electrified railway, so that certain harm is generated to the safety of a public power grid and the quality of electric energy.
The impact effect of the electrified railway traction power supply load accessing to the power grid needs to be researched and calculated during planning and design so as to determine the influence of the impact effect on the transient stability of the power grid. At present, related and systematic modeling methods are few, and the coordinated development of a power grid and an electrified railway is restricted to a certain extent. Therefore, in order to ensure the safety of the power grid, meet the requirement of the crossing type development of the electrified railways and help the sustainable and rapid growth of the economy in China, the problem needs to be systematically and deeply researched, impact loads of traction power supply of different electrified railways are simulated and calculated, the power utilization reliability of the electrified railways is ensured, the operation safety of the power grid is guaranteed, and the coordination degree of power grid planning and the development planning of the electrified railways is improved.
Disclosure of Invention
Aiming at the prior art, the technical problem to be solved by the invention is to provide the modeling method for the traction power supply load of the electrified railway based on parameter identification, which can better describe the impact effect of the traction power supply load of the electrified railway accessing to the power grid, support the power grid planning and the development planning of the electrified railway and improve the coordination degree of the power grid planning and the development planning of the electrified railway.
In order to solve the problems, the modeling method of the electrified railway traction power supply load based on parameter identification comprises the following steps:
step 1, combining the characteristics of a load locomotive of an electrified railway in the advancing process, directly integrating direct current motor load and comprehensive load on a power supply arm of a contact network to determine a mathematical model of an alternating current-direct current electric locomotive, directly integrating three-phase alternating current motor load and comprehensive load on the power supply arm of the contact network to determine the mathematical model of the alternating current-direct current electric locomotive, integrating the mathematical model of the alternating current-direct current electric locomotive and the mathematical model of an alternating current-direct current high-speed electric locomotive, establishing an electric locomotive comprehensive model, combining the impact characteristics of the traction power supply load of the electrified railway, determining a model of the impact characteristics of the traction power supply load of the electrified railway, and introducing a switching coefficient to obtain a formula
Identifying and analyzing an expression model of the electric locomotive model of the electrified railway;
step 2, establishing a conversion model between the three-phase side voltage of the power system and the two-phase voltage of the traction power supply system of the electrified railway, carrying out mathematical modeling on the power demand initiative characteristic of the electrified railway load by combining the starting, accelerating and cross-electricity split-phase advancing characteristics of the electrified railway load, and establishing a formula-based identification and analysis expression model by combining the identification and analysis expression model of the electric locomotive model of the electrified railway
Determining an impact load model structure of the electrified railway;
step 3, selecting a certain electrified railway traction station for testing, and analyzing and preprocessing the measured data of the traction power supply load of the electrified railway;
and 4, identifying typical parameters in the traction power supply load model of the electrified railway, and analyzing and verifying the accuracy of the traction power supply load model of the electrified railway by adopting corresponding examples.
The traction power supply load of the electrified railway is a time-varying load moving in space and is a dynamic and nonlinear load. The result of the traditional statistical synthesis method is correct only for a certain time section, and insufficient description capacity is provided for the time-varying load of the electrified railway; the method is based on a modeling strategy combining a mechanism formula and an input/output formula, the traction power supply load of the electrified railway is regarded as a grey system, a load characteristic model and an impact characteristic model of the load of the electrified railway are established, and the load characteristic model and the impact characteristic model are integrated into a unified impact load model of the electrified railway.
As a further improvement of the invention, in the step 1, the structure of the power function is represented by a formula
Determining comprehensive load model, mathematical model of AC-DC electric locomotive
Determining the mathematical model of AC-DC-AC electric locomotive
And (4) determining. The comprehensive load model is established by adopting the structure of the power function, so that the identification parameters can be reduced, and the identification efficiency and the identification precision of the main parameters of the model can be improved.
As a further improvement of the invention, in the step 2, the mathematical modeling method for the power demand initiative characteristic of the electrified railway load is that the power demand initiative characteristic of the locomotive is equivalent to a power change process similar to a trapezoid, the power demand initiative characteristic is expressed by a mathematical model of a step function, and the established model is expressed by a formula
And (4) determining.
The trapezoidal model is adopted to describe the active power characteristics of the electrified railway load, and the load characteristics and the impact characteristics of the load can be accurately reflected: the method has better description on the process of sharp rise and fall of the load power demand of the electric locomotive, and has ideal fitting effect in the time period of power fine adjustment.
As a further improvement of the invention, in the step 1, the impact characteristic of the traction power supply load of the electrified railway is represented by a formula
And (4) determining.
Since the electrified railway load is a typical impact load, in order to express the impact characteristic of the electrified railway load on a time domain model, an equation is introduced to better reflect the actual electrified railway power change process.
As a further improvement of the present invention, in the step 3, the method for analyzing and preprocessing the measured data of the traction power supply load of the electric railway comprises the following steps:
step 31, selecting a certain substation bus for supplying power to the traction station as a measurement point, taking a group of typical and complete impact characteristic curves measured at the bus as analysis objects, and measuring change curves of voltage, current and apparent power in a time period;
and 32, filtering and denoising the measured data by adopting a wavelet decomposition technology to complete the pretreatment work of the measured data.
In terms of load components, the load data measured at the PCC point includes not only the load of the low-voltage side traction power supply system, but also a certain proportion of other user loads, which causes a certain noise to be included in the measured signal. In terms of the characteristics of the impact load, a large amount of noise may mask the impact characteristics of the impact load to some extent. Therefore, in order to eliminate the adverse effects of the above factors as much as possible, the measured data must be preprocessed to improve the accuracy of the load modeling and parameter identification.
As a further improvement of the present invention, in step 4, when the typical parameters in the traction power supply load model of the electrified railway are identified, the improved PSO algorithm of the linear decreasing weight policy (LDIW) is selected to identify the typical independent parameters according to the analysis result of the sensitivity of the parameters. In a parameter identification implementation, in order to find the best balance between global search and local search, a linear decreasing weight strategy (LDIW) is adopted to improve the PSO algorithm.
The invention has the beneficial effects that:
at present, the research on the impact load modeling of the power system is in an immature stage, and a systematic impact load modeling theory is not formed yet. During planning of the power system, due to the lack of an accurate dynamic impact load model, a static model is often adopted for replacement; most of impact load models adopted for actual power grid operation mode calculation are static or induction motor parallel static characteristic load models. On the other hand, for modeling the traction load of the electric railway, the research at home and abroad is not deep at present, and the research on the aspect of the impact characteristic is less related, so that the modeling analysis of the traction power supply load of the electric railway based on parameter identification is carried out on the impact load of the electric railway, and the modeling analysis mainly has the following characteristics:
(1) the method is characterized in that structural and mechanism analysis is carried out on an electrified railway traction power supply system and an electric locomotive, the characteristics of traction load of the electrified railway are summarized, and particularly, phenomenon analysis and explanation are carried out on the impact characteristics of the traction load.
(2) Analyzing by combining with an actual measurement load curve of the impact load of the electric iron, and explaining the phenomenon shown by the load curve; and denoising the actually measured load curve by adopting a wavelet analysis method, and identifying the denoised data as model parameters.
(3) And respectively establishing load characteristic models of the AC-DC type electric locomotive and the AC-DC-AC type electric locomotive facing the PCC points of the power grid, integrating the load characteristic models into a unified electric railway load characteristic model, and adding an analytical expression for describing the impact characteristic of the electric railway impact load to form an electric railway impact load comprehensive model structure. And establishing and implementing a model parameter identification strategy. The feasibility of the modeling method, and the correctness and effectiveness of the built model are verified through example analysis.
(4) And improving the model aiming at the initiative characteristic of the impact load, and comparing and analyzing the model with the original model.
According to the modeling method for the traction power supply load of the electrified railway based on parameter identification, the impact effect of the traction power supply load of the electrified railway accessing to the power grid can be better described, the power grid planning and the development planning of the electrified railway are supported, the coordination degree of the power grid planning and the development planning of the electrified railway is improved, the safety of the power grid is ensured, and the crossing development requirement of the electrified railway is met.
Drawings
FIG. 1 is an equivalent diagram of the traction load of an electrified railway;
FIG. 2 is a graph of measured voltage, current, and apparent power;
FIG. 3 is a graph of a curve after denoising;
FIG. 4 is a block diagram of the overall process;
FIG. 5 is a flow chart of an impact load model implementation;
FIG. 6 is a simulated power plot of load model I;
FIG. 7 is a simulated power plot for load model II;
fig. 8 is a block diagram of an embodiment of the present invention.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the attached drawings, and the block diagram of the scheme of the present invention is shown in fig. 8, and the specific steps are as follows:
establishing an electrified railway traction power supply load model capable of describing load impact characteristics, improving an expression of the electrified railway traction power supply load model by combining characteristics of an electrified railway load locomotive in the advancing process, and establishing an identification analysis expression of the electrified railway traction power supply load model.
According to the characteristic that the traction power supply load model of the electrified railway faces to the PCC point of the power system, a conversion model between the three-phase side voltage of the power system and the two-phase voltage of the traction power supply system of the electrified railway is established. The traction station changes three-phase voltage into two-phase voltage through a traction transformer, namely the conversion between the voltage of a three-phase side and the voltage of a power supply arm of a contact network.
The transformation relation between the three-phase side voltage and the voltage of the power supply arm of the contact network is as follows:
wherein,the voltage of the power supply arm is supplied to the contact network,the transformation ratio from the traction transformer to the power supply arm port;the angle is a wiring angle of a port of the traction main transformer;the voltage is the three-phase voltage of the power system side. Is provided withThe effective value of the voltage of the three-phase side is the effective value of the voltage of the power supply arm of the contact networkCan be obtained by the following formula.
Definition ofFor the contact net supply arm voltage to the conversion coefficient of three-phase side voltage virtual value, then:
a load model of 'direct current motor parallel comprehensive load' is adopted to describe the load characteristics of the alternating current and direct current electric locomotive, the direct current motor load and the comprehensive load are directly integrated on a power supply arm of a contact network, and a mathematical model of the alternating current and direct current electric locomotive is established.
The load of the AC-DC electric locomotive is mainly composed of a traction motor, auxiliary equipment and a cab, and the traction motor of the AC-DC electric locomotive is similar to a DC motor. Therefore, the load of the AC-DC electric locomotive is described by adopting a model of 'traction motor parallel comprehensive load'. The state equation and the absorbed active power equation of the traction motor are as follows:
in the above formula:in order to pull the motor loop terminal voltage,andis a generalized equivalent parameter of the traction motor,andas is the current and speed of the traction motor,LandRrespectively an inductor and a resistor of a traction motor loop; j is the moment of inertia of the traction motor.For mechanical load torque, a quadratic function model of the rotating speed is adopted to describe the mechanical load torque,T L0 is the traction motor load rate.
Setting the bus voltage of the PCC point asThen, the following relationship holds:
the voltage transformation coefficient is obtained from equation 1. Substituting the formula 3 into the formula 2 to obtain a state equation of the traction motor circuit taking the voltage of the three-phase side of the system as excitation:
in order to reduce identification parameters and improve the identification efficiency and accuracy of main parameters of the model, a description comprehensive load model can be represented in a power function form.
Wherein,the index characteristic of the load is reflected, and the index characteristic is an object identified by the load model parameters;determined by steady state operating conditions.
In order to improve the adaptability of the model, the initial active power and reactive power proportional coefficient of the direct current traction motor is introducedThen, there are:
wherein,for the initial total active and reactive power of the model,. Therefore, the model structure of the ac-dc electric locomotive is composed of formula 4, formula 5, and formula 6. The total power output is shown in equation 7.
A load model of a three-phase alternating current motor parallel comprehensive load is adopted to describe the load characteristics of the alternating current and direct current type electric locomotive, the three-phase alternating current motor load and the comprehensive load are directly integrated on a power supply arm of a contact network, and a mathematical model of the alternating current and direct current type electric locomotive is established.
The traction transmission system of the AC-DC-AC electric locomotive mainly comprises a traction transformer, a traction converter and a traction motor, wherein the traction motor adopts a three-phase asynchronous motor. The dynamic part of the locomotive load is described by a 3-order electromechanical transient motor model; the comprehensive part is described by adopting an exponential function comprehensive load model which ignores the influence of frequency change.
3-order asynchronous motor state equation:
the absorbed power is:
wherein,is an electromotive force after the transient reactance is generated,is a transient reactance, and is therefore,in order to be a synchronous reactance,as a function of the time constant of the transient state,is the constant of the time of inertia,is a mechanical torque;respectively the rotor speed and the synchronous speed,the work angle is shown.
Setting the bus voltage of the PCC point asThe following relationship holds for the analysis:
the AC-DC-AC electric locomotive model is formed by connecting a three-phase AC motor model and a comprehensive load model in parallel. The comprehensive load adopts formula 5. Therefore, the model structure of the ac-ac type electric locomotive is composed of formula 8, formula 9, formula 10, and formula 5.
The model power total output is:
in order to improve the adaptability of the model, the initial active power proportionality coefficient of the three-phase alternating current motor is introducedThen, there are:
wherein,for the initial total active power of the model,the initial active power of the integrated load.
Based on the analysis, the electric locomotive model is established by facing to a substation PCC point for supplying power to the traction station of the electrified railway, and the model comprehensively takes the loss of the power transmission line and the traction power supply system into consideration, so that the model can be used for describing the characteristics of the traction power supply system of the electrified railway and the load of the electric locomotive along with the change of the system voltage. The electric locomotives of the railway system are various in types, and the types of the electric locomotives on different lines are different. Therefore, it is necessary to integrate the two types of models to form a load characteristic model of the electric railway with diversified description capability. The load model equivalent diagram after integration is shown in fig. 1.
Defining the switching coefficients of the three-phase AC motor load and DC motor load respectively asAndwherein、The value of 0 or 1 is selected,andnot simultaneously 0. The following model structure is obtained according to equation 7 and equation 11:
a. when in use,The model is an AC-DC electric locomotive load model;
b. when in use,The model is an AC/DC type electric locomotive load model;
c. when in use,The model is a hybrid load model of AC-DC type and AC-DC-AC type locomotives.
In the formula,total active and reactive power;、active and reactive power absorbed for the three-phase alternating current motor;is a direct currentActive power absorbed by the motor; a、The active and reactive power absorbed for the combined load.
Since the electrified railway load is a typical impact load, in order to express the impact characteristic of the electrified railway load on a time domain model, an equation is introduced to better reflect the actual electrified railway power change process. Therefore, a model for describing the impact characteristics of the traction power supply load of the electrified railway can be obtained by a formula
And (4) determining. Wherein,in order to be at a steady-state voltage,the coefficients of variation of active and reactive impulse power with voltage are provided.
And (3) synthesizing the impact characteristics of the traction power supply load of the electrified railway with the model of the formula 12 to obtain the comprehensive model structure of the impact load of the electrified railway shown in the formula 14.
The active demand for power during the actual traveling of the electric locomotive is divided into two aspects:
a. starting and accelerating the process; during starting and acceleration of the electric locomotive, the load torque of a traction motor can change greatly.
b. Cross-electric phase splitting; when the electric locomotive crosses the electric phase separation at a larger speed, the electric locomotive can be applied to the electric power system to impact power instantaneously.
Therefore, the mathematical modeling method for the power demand initiative characteristic of the electrified railway load comprises the steps of firstly, equating the power demand initiative characteristic of a locomotive to a power change process similar to a trapezoid, and then, determining the mathematical structure of a trapezoid power change curve through system identification.
The power activity requirement can be expressed using a mathematical model of a step function as follows:
wherein,、are the parameters to be identified respectively, and are,is a unit step function;the power corresponding to the horizontal part, the ascending part and the descending part of the curve in the trapezoidal power change diagram respectively;the three are the comprehensive impact power after being superposed on a time axis. Equation 15 can be used to factor through power if active and reactive power surges are considered separatelyAnd (6) obtaining.
The trapezoidal model is adopted to describe the active power characteristics of the electrified railway load, and the load characteristics and the impact characteristics of the load can be accurately reflected: the method has better description on the process of sharp rise and fall of the load power demand of the electric locomotive, and has ideal fitting effect in the time period of power fine adjustment.
The power characteristics described in equation 14 are superimposed with the power characteristics described in equation 15 to improve the mathematical description of the impact load of the electrified railway. The improved impact load model of the electrified railway isThe load model shown in equation 14 isThe model shown in equation 15 isThe improved structure of the impact load model of the electrified railway is expressed by formula 16.
Wherein,、、、is the parameter to be identified. By passingImplementing the previously established parameter identification strategy results in a complete model.
Considering the identifiability of the model, according to the parameter sensitivity analysis result, selecting the following parameters as the independent parameters to be identified:
typical values for the other parameters in the model are shown in table 1.
And selecting a typical electrified railway traction station for testing, and analyzing and preprocessing the measured data of the traction power supply load of the electrified railway.
A method for analyzing and preprocessing the actually measured data of the traction power supply load of an electrified railway is characterized by measuring buses of a plurality of electrified railway traction substations in a certain area and a system substation on the opposite side and recording the change curves of voltage, current and apparent power in a time period. A typical and complete set of impact characteristics measured at the bus bar is used as an analysis pair, as shown in fig. 2. In the figure, the abscissa is the number of sampling points, the sampling frequency is power frequency, the sampling interval is 0.02s each time, the total duration is 48s, the ordinate is a per unit value, and the reference value is the value of each electric quantity at 0 moment.
In terms of load components, the load data measured at the PCC point includes not only the load of the low-voltage side traction power supply system, but also a certain proportion of other user loads, which causes a certain noise to be included in the measured signal. In terms of the characteristics of the impact load, a large amount of noise may mask the impact characteristics of the impact load to some extent. Therefore, in order to eliminate the adverse effects of the above factors as much as possible, the measured data must be preprocessed to improve the accuracy of the load modeling and parameter identification.
And filtering the measured data by adopting a wavelet analysis technology. And (5) performing 5-layer decomposition on the measured data by adopting a db5 wavelet to obtain a measured signal curve of the figure 3, and finishing the pretreatment work of the measured data.
And identifying typical parameters in the traction power supply load model of the electrified railway, and analyzing and verifying the accuracy of the traction power supply load model of the electrified railway by adopting corresponding examples.
A method for identifying typical parameters in a traction power supply load model of an electrified railway is characterized in that as the number of the parameters to be identified of the model is relatively large, in order to improve identification accuracy and optimization efficiency, a PSO algorithm (particle swarm) is selected, and a linear decreasing weight strategy (LDIW) is adopted to improve the PSO algorithm.
And programming the impact load model of the electrified railway shown in the formula 15 in Matlab, and obtaining model parameters. The general framework of the procedure is shown in figure 4. The program is roughly divided into two layers, and the program inner layer is arranged in a dotted line frame. The outer layer is a model parameter identification process based on LDIW-PSO, and the inner layer is a detailed implementation of formula 15. The program inner layer realizes the flow.
For convenience of description, equation 15 is called as model I, equation 16 is used as model II, and model I and model II are identified by using the measured data shown in fig. 5, and the simulation results of model I and model II are shown in fig. 6 and fig. 7.
(1) Model II has better fitting accuracy than model I. The main reasons are considered as follows:
the model I takes bus voltage as excitation and solves the power response of the load through a state equation. The model can well reflect the change of the load power demand when the power grid voltage changes under different working conditions, and the power demand of the model completely depends on the bus voltage of the power grid. The measured power is obtained by calculating the outgoing line current of the transformer substation and is the actual power of the traction power supply system; and the measured PCC point voltage is influenced by the load of the traction power supply system and also depends on the change of other electric loads. That is, the measured data includes not only the impact characteristic of the electric locomotive but also the load characteristic thereof, and also the characteristics of a certain amount of other loads. Therefore, this situation may cause the model to fall into a local overfitting state around the voltage disturbance, causing fitting errors.
And the model II is added with the analytic expression of the active required power at the moment of extremely high power impact on the basis of the model I, so that the model shows better impact characteristics. On one hand, the active power does not depend on the system voltage, is determined by the operating condition of the locomotive, and effectively gets rid of identification errors caused by the influence of other loads on the system bus voltage. On the other hand, the addition of the active required power expands the scale of the model for impact characteristic description, so that the original model is more concentrated on the tiny power change description, and the reduction of the power change is facilitated、The value of (a). Therefore, the model II has better fitting to the impact characteristics, and simultaneously retains the description capacity of the original model to the load characteristics and the impact characteristics.
(2) Model I has better generalization ability than model II.
The impact load of the electrified railway has strong randomness, the amplitude, the occurrence time and the duration of the power impact are different, and the electrified railway does not have the characteristic of strict periodic variation. The model II cannot track the load accurately in real time to generate the characteristic points of active power impact.
(3) The model I is suitable for load prediction and electrified railway development planning under the condition of low precision requirement; the model II can be used for correcting the identification result of the model I and is suitable for analyzing the influence of the impact load of the electrified railway on the power grid.
Since model II does not change the load characterization of the model impact load, only 7 parameters shown in table 2 need to be identified. The fitness function value calculation result is 0.0132.
。
Claims (6)
1. A method for modeling traction load of an electrified railway based on parameter identification is characterized by comprising the following steps:
step 1, combining the characteristics of a load locomotive of an electrified railway in the advancing process, directly integrating direct current motor load and comprehensive load on a power supply arm of a contact network to determine a mathematical model of an alternating current-direct current electric locomotive, directly integrating three-phase alternating current motor load and comprehensive load on the power supply arm of the contact network to determine the mathematical model of the alternating current-direct current electric locomotive, integrating the mathematical model of the alternating current-direct current electric locomotive and the mathematical model of an alternating current-direct current high-speed electric locomotive, establishing an electric locomotive comprehensive model, combining the impact characteristics of the traction power supply load of the electrified railway, determining a model of the impact characteristics of the traction power supply load of the electrified railway, and introducing a switching coefficient to obtain a formula
Identifying and analyzing an expression model of the electric locomotive model of the electrified railway;
step 2, establishing a conversion model between the three-phase side voltage of the power system and the two-phase voltage of the traction power supply system of the electrified railway, carrying out mathematical modeling on the power demand initiative characteristic of the electrified railway load by combining the starting, accelerating and cross-electricity split-phase advancing characteristics of the electrified railway load, and establishing a formula-based identification and analysis expression model by combining the identification and analysis expression model of the electric locomotive model of the electrified railway
Determining an impact load model of the electrified railway;
step 3, selecting a certain electrified railway traction station for testing, and analyzing and preprocessing the measured data of the traction power supply load of the electrified railway;
and 4, identifying typical parameters in the traction power supply load model of the electrified railway, and analyzing and verifying the accuracy of the traction power supply load model of the electrified railway by adopting corresponding examples.
2. The method for modeling traction load of electric railway based on parameter identification as claimed in claim 1, wherein in step 1, the structure of power function is represented by formula
Determining comprehensive load model, mathematical model of AC-DC electric locomotive
Determining the mathematical model of AC-DC-AC electric locomotive
And (4) determining.
3. The method according to claim 1 or 2, wherein in step 2, the power demand initiative characteristic of the electrified railway load is mathematically modeled by equating the power demand initiative characteristic of the locomotive to a trapezoidal power change process, the power initiative characteristic is represented by a mathematical model of a step function, and the model is established by a formula
And (4) determining.
4. The method for modeling traction load of electric railway based on parameter identification as claimed in claim 1, wherein in the step 1, the impact characteristic of traction power supply load of electric railway is represented by formula
And (4) determining.
5. The method for modeling traction load of electric railway based on parameter identification as claimed in claim 1, wherein the step 3, the method for analyzing and preprocessing the measured data of traction power supply load of electric railway comprises the following steps:
step 31, selecting a certain substation bus for supplying power to the traction station as a measurement point, taking a group of typical and complete impact characteristic curves measured at the bus as an analysis object, and measuring change curves of voltage, current and apparent power in a time period;
and 32, filtering and denoising the measured data by adopting a wavelet decomposition technology to complete the pretreatment work of the measured data.
6. The method of claim 1, wherein in the step 4, when the parameter identification is performed on the typical parameter in the model of the traction power supply load of the electric railway, the improved PSO algorithm of a linear decreasing weight strategy (LDIW) is selected to identify the typical independent parameter according to the result of the parameter sensitivity analysis.
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