Traction power supply electric energy treatment method based on HAPF and quadruple RPC

Abstract

The invention discloses a traction power supply electric energy treatment method based on HAPF and quadruple RPC, and relates to the technical field of high-speed railway electric power, and the method comprises the steps: analyzing the electric energy quality problem of a traction power supply system; building an engineering model of a traction power supply system and key components thereof; a quadruple RPC model based on limited LMI amplitude-phase control is established, and a hybrid energy storage device including a lithium battery and flywheel energy storage is introduced; constructing a motor train unit model, and designing eight working conditions; an HAPF model is constructed, and parameters are adjusted under various working conditions; and performing multi-working-condition electric energy quality analysis on the traction power supply system. According to the traction power supply system electric energy management method based on the hybrid active power filter (HAPF) and the quadruple RPC, the electric energy quality problem of rail transit is effectively solved, and remarkable economic benefits are brought to railway operation.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a traction power supply electric energy management method based on HAPF and quadruple RPC. Background Art

[0002] In today's electrified transportation, the traction power supply system plays a vital role. With the continuous development of railway transportation and the widespread application of power electronics technology, the scale and complexity of the traction power supply system are increasing. However, due to the presence of a large number of nonlinear loads in the traction power supply system, such as the rectifier and inverter of the electric locomotive, serious power quality problems will occur.

[0003] Harmonic pollution is one of the main problems faced by traction power supply systems. Harmonic currents can cause grid voltage distortion, increase line losses, affect the normal operation of electrical equipment, and may even cause equipment failures and malfunctions of protection devices. In addition, reactive power can also have an adverse effect on the traction power supply system, reduce the system's power factor, and increase the burden on the grid.

[0004] In order to solve these power quality problems, the traditional method mainly uses passive filters. However, passive filters have some limitations, such as only filtering specific harmonics, easily resonating with the power grid, and limited compensation effect. With the development of power electronics technology, active power filters have gradually become a research hotspot. Active power filters have the advantages of fast dynamic response, high compensation accuracy, and the ability to compensate harmonics and reactive power at the same time.

[0005] However, the cost of using active power filters alone is high and the capacity is limited. Therefore, the hybrid active power filter (HAPF) that combines the advantages of passive filters and active power filters came into being. HAPF can effectively overcome the shortcomings of passive filters and active power filters and improve the effect and economy of quadruple RPC power quality compensation.

[0006] In summary, in order to meet the power quality requirements of the traction power supply system, it is of great practical significance to develop a traction power supply system power quality analysis and compensation technology based on HAPF. Summary of the invention

[0007] The purpose of the present invention is to provide a traction power supply electric energy management method based on HAPF and quadruple RPC in order to improve the power supply quality of the traction power supply system.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] A traction power supply power management method based on HAPF and quadruple RPC, the method comprising the following steps:

[0010] Constructing an engineering model of a traction power supply system and its key components, wherein the traction power supply system and its key components include a three-phase power system and a traction transformer, wherein two power supply arms are connected to both sides of the secondary winding of the traction transformer, and the power supply arms are connected to the main circuit of the train;

[0011] Connecting a quadruple RPC model based on limited LMI amplitude and phase control in parallel at both ends of the traction power supply system, wherein the busbar of the RPC model is connected to an energy storage device;

[0012] The working conditions of the train are set, and the parameters of the hybrid active filter are set based on the working conditions. The hybrid active filter is arranged on the power supply arms on both sides of the traction power supply system to control the operation of the main circuit of the traction power supply system and the train under various working conditions.

[0013] Furthermore, the quadruple RPC model is four RPC modules connected in parallel, each RPC module includes a back-to-back converter, and the back-to-back converter is controlled by a total compensation current command signal of the corresponding RPC module, and the total compensation current command signal is:

[0014]

[0015] in, and Respectively represent the compensation current command signals of the converters corresponding to the two power supply arms, i' α and i' β is the compensated bilateral traction current, i αl and i βl Represents the load current of the two arms.

[0016] Furthermore, the compensated bilateral traction current is:

[0017]

[0018] Among them, I' p It represents the active current amplitude after active power transfer balance, ω is the angular frequency, and t represents time.

[0019] Furthermore, the RPC module is controlled through a voltage and current double closed loop, wherein the controller used for RPC amplitude and phase control is a limited controller based on LMI, and the state equation of the limited controller is:

[0020]

[0021] Where u is the control input, x = [x1 x2]';

[0022] A represents the system matrix, which describes the relationship between the state variables within the system; B is the input matrix, which describes how the input affects the state of the system; x1 and x2 represent state variables.

[0023] The controller is:

[0024] u=Kx

[0025] Where K = [k1 k2], k1 and k2 are controller parameters.

[0026] The control objective is to achieve x→0,|u|≤u by designing LMI max ,

[0027] Among them, u max Indicates the maximum value of the control input, Indicates the maximum rate of change of control input.

[0028] Controller Design:

[0029] Design Lyapunov function:

[0030] V=x'Px

[0031] V(0)=x'0Px0

[0032] Where P is a positive definite matrix and P>0, P=P', V represents the value of the Lyapunov function, V(0) represents the value of the Lyapunov function in the initial state, x0 represents the initial state variable of the system, let F=KP -1 ,N=P -1 , The following five LMI formulas are obtained:

[0033] αN+AN+BF+NA'+F'B'<0

[0034]

[0035] P>0,P=P',→N>0,N=N'

[0036]

[0037] Among them, α represents a given constant, N represents the inverse of the positive definite matrix, Represents a positive number. Using the above five LMI formulas, design an appropriate input u max , α, and find the effective K.

[0038] Furthermore, the energy storage device includes a lithium battery energy storage part and a flywheel energy storage part.

[0039] Furthermore, when the lithium battery energy storage part is in a discharge state, bat >0,V g 、V a , R d They are:

[0040]

[0041] When charging bat <0, R d 、V a 、V g They are:

[0042]

[0043] Among them, V g 、V a , R d They represent the charging voltage tail rise, the maximum saturation voltage drop, and the battery discharge internal resistance, V a0 Indicates V a Constant value, V a1 Indicates V a Coefficient of variation, SOC represents the state of charge, S a For SOC to V a The impact point, S b For SOC to V g The influence point, R0 represents the internal resistance constant, R1 represents the internal resistance variation coefficient, S d represents the threshold state of charge, i bat Represents the battery current, R c Represents the charging internal resistance, V ga Indicates the charging voltage coefficient.

[0044] Furthermore, the flywheel energy storage part adopts speed-current dual closed-loop speed control when in charging state, and adopts voltage-current dual closed-loop control when in discharging state;

[0045] The transfer function of the current loop in the speed-current dual closed-loop speed control is:

[0046]

[0047] Among them, s is the Laplace operator, T is the time constant, and K is the proportional coefficient;

[0048] The open-loop transfer function of the speed loop is:

[0049]

[0050] Among them, K m Represents the torque constant, K t is the back electromotive force constant, τm represents the electromechanical time constant, J represents the moment of inertia, T s represents the time constant;

[0051] The closed-loop transfer function of the voltage loop in the voltage-current dual closed-loop control is:

[0052]

[0053] Among them, T u represents the time constant of the voltage loop, C d Represents the DC bus capacitance, T q Represents electromagnetic torque, K up Represents the proportional gain of the voltage loop.

[0054] Further, the hybrid active filter is a passive filter and an active filter connected in series;

[0055] The nth order passive filter at frequency ω n =ω a The impedance Z n for:

[0056]

[0057] Among them, R n represents the nth passive filter resistance, ω a represents the frequency of the passive filter of order a (a is a positive integer), ω n represents the nth passive filter frequency, L n represents the nth order passive filter inductance, C n represents the passive filter capacitance of n times;

[0058] The capacitive reactive power of the DC side capacitor compensation of the active filter is:

[0059] ΔE(t)=Sk

[0060]

[0061] Among them, ΔE(t) represents the change value of the capacitance within one cycle, S represents the compensation size, k represents the transformation ratio, C represents the DC side capacitance, and ΔU m Indicates the voltage fluctuation range, U * m Indicates the regulated voltage value.

[0062] On the other hand, the present invention also proposes a traction power supply electric energy management system based on HAPF and quadruple RPC, including a memory, a processor, and a program stored in the memory, and the processor implements the above method when executing the program.

[0063] Another aspect of the present invention provides a computer-readable storage medium having a program stored thereon, wherein the program implements the above method when executed.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] There are a large number of nonlinear loads such as electric locomotives in the traction network, which will generate abundant harmonic currents. In addition, due to the volatility of the electric locomotive load, the reactive power demand varies greatly. The active part of HAPF can dynamically track and compensate for the changing harmonic currents, while the passive part can effectively filter out harmonics of specific frequencies. The quadruple RPC can use its multi-unit structure and flexible control strategy to more accurately analyze and process the fundamental and harmonic frequency components of harmonics. HAPF can further enhance the suppression effect of high-order harmonics, especially those with fast frequency changes and small amplitudes, through the fast dynamic response of the active part based on the harmonic information provided by the quadruple RPC, thereby greatly improving the compensation accuracy and range of the entire system for harmonics. In terms of reactive power compensation, the quadruple RPC mainly focuses on large-capacity dynamic compensation of the reactive power of the traction power supply system to improve the power factor. HAPF also has certain functions in reactive power compensation. It can perform refined reactive power regulation based on the actual reactive power demand of the system and the reactive power compensation strategy of the quadruple RPC.

[0066] In the traction power supply system, the quadruple RPC needs to simultaneously handle multiple complex power quality issues such as negative sequence, harmonics and reactive power. LMI control can take these issues into consideration and construct a control target x→0,|u|≤u containing multiple performance indicators. max , This is different from general motor control which mainly focuses on single or a few performance indicators such as speed or torque. It can achieve more comprehensive power quality optimization in the traction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 A schematic diagram of a flow chart of an embodiment of the present invention;

[0068] Figure 2 It is the overall structural diagram of the present invention;

[0069] Figure 3 This is a diagram of the RPC single-sided equivalent circuit model of the present invention;

[0070] Figure 4 It is the control logic block diagram of both sides of RPC of the present invention;

[0071] Figure 5 This is a lithium battery model diagram of the present invention;

[0072] Figure 6is a main circuit diagram of the train of the present invention;

[0073] Figure 7 This is a current waveform diagram of the grid side of the present invention;

[0074] Figure 8 It is the harmonic content of the grid-side current under 8 working conditions after HAPF filtering in the present invention;

[0075] Fig. 9 It is a voltage waveform diagram of the traction network side of the present invention;

[0076] Fig.10 It is a current waveform diagram of the traction network side of the present invention;

[0077] Fig.11 The present invention selects four working conditions for the comparison of current harmonic content on the traction network side;

[0078] Fig.12 The present invention selects four working conditions for comparison of voltage harmonic content on the traction network side;

[0079] Fig.13 This is the 0.2s-0.4s traction network side current harmonic diagram under the double-row traction condition of the present invention;

[0080] Fig.14 is a current waveform diagram of the locomotive side of the present invention;

[0081] Fig.15 It is the harmonic content of the current of the locomotive side in eight working conditions before HAPF filtering in the present invention;

[0082] Fig.16 is the harmonic content of 8 working conditions on the locomotive side after HAPF filtering in the present invention;

[0083] Fig.17 The present invention selects the harmonic content comparison of 4 working conditions on the locomotive side, and displays the harmonic comparison diagram before and after HAPF filtering under the 1st, 2nd, 3rd and 5th working conditions;

[0084] Fig.18 It is a harmonic comparison diagram before and after locomotive current filtering under the working conditions of one train traction and one train braking on the α side and a single train traction on the β side of the present invention;

[0085] Fig.19 This is the FFT diagram of the traction network current before filtering in the case of working condition 4 of the present invention;

[0086] Fig. 20 This is the FFT diagram of the traction network current after filtering in the case of working condition 4 of the present invention; DETAILED DESCRIPTION

[0087] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0088] In order to overcome the problems of harmonic amplification and excessive negative sequence imbalance, the present invention proposes a traction power supply power management method based on HAPF and quadruple RPC. By building a self-built traction power supply system regenerative braking model, a richer train operation condition is obtained, and the harmonics and negative sequence problems caused by locomotive traction braking on the grid side under various conditions are analyzed in detail. Harmonic management is performed using HAPF from a multi-condition perspective, which is more in line with the engineering practice of the traction power supply system.

[0089] The present invention provides the following technical solution: a traction power supply electric energy management method based on HAPF and quadruple RPC, comprising:

[0090] Step 1: Analyze the power quality problems of the traction power supply system;

[0091] Step 2: Establish an engineering model of the traction power supply system and its key components;

[0092] Step 3: Build a quadruple RPC model based on limited LMI amplitude and phase control, and introduce a hybrid energy storage device, including lithium batteries and flywheel energy storage;

[0093] Step 4: Build a train model and design 8 working conditions;

[0094] Step 5: Build the HAPF model and adjust the parameters under various working conditions;

[0095] Step 6: Conduct power quality analysis of the traction power supply system under multiple operating conditions.

[0096] The traction transformer is the core equipment for energy conversion in the traction power supply system. In the railway power supply system, the power system transmits three-phase alternating current, while traction equipment such as EMUs require single-phase alternating current to operate. The traction transformer is like an "energy translator", converting three-phase alternating current into single-phase alternating current so that the electric energy can be transmitted to the EMU in a suitable form. The selected V / v connection method is composed of two single-phase transformers. The primary winding is connected to two phases of the three-phase power system, such as phase A and phase B, to obtain the grid line voltage, and the two sides of the secondary winding are connected to the power supply arms α and β respectively. There are electric locomotives running under the power supply arms on both sides. The grid power in the system is provided to the locomotive through the pantograph to support the energy required for the operation of the locomotive. The required current is then returned to the transformer through the rails. The primary winding voltage is the line voltage. For three-phase 110kV or 220kV systems, the line voltage is the phase voltage. The simulation parameters of the traction power supply system are shown in Table 1.

[0097] Table 1 Traction power supply system simulation parameters

[0098]

[0099] The left power supply arm is α phase, the right power supply arm is β phase, and the voltage of the two arms is:

[0100]

[0101] u A 、u B 、u C is the three-phase voltage on the grid side, and k is the transformer turns ratio. The three-phase AC current on the grid side can be further obtained based on the load of the power supply arm:

[0102]

[0103] As a preferred solution of the traction power supply power management method based on HAPF and quadruple RPC described in the present invention, the present invention realizes the management of power quality by connecting multiple topology RPC and other devices in parallel. RPC is connected in parallel to the traction power supply system, in which each converter compensates a power supply area separately, and each traction line is regarded as a single-phase load. Then, active power and reactive power are transmitted and converted between the two-phase loads to ensure the safe and reliable operation of the train, while improving the efficiency and stability of the power supply system.

[0104] The present invention achieves power quality management by connecting multiple topology RPC and other devices in parallel. RPC is connected in parallel to the traction power supply system, where each converter compensates a power supply area separately, and each traction line is regarded as a single-phase load. Then, active power and reactive power are transmitted and converted between the two-phase loads to ensure the safe and reliable operation of the train, while improving the efficiency and stability of the power supply system.

[0105] The steady-state mathematical model of the RPC single-side converter is:

[0106]

[0107] Set the detected load current of the two arms to i αl 、i βl , then:

[0108]

[0109] Combining the trigonometric formulas, we can expand the above formula to get:

[0110]

[0111] According to the principle of phase detection, the load current amplitudes of the two arms are multiplied by their corresponding voltage synchronization signals to deduce the load currents of the two arms. Further simplification can be obtained.

[0112]

[0113] The compensated bilateral traction current is:

[0114]

[0115] The total compensation current command signal required for RPC system compensation is:

[0116]

[0117] The PI control in the traditional RPC amplitude and phase control is optimized to a limited control based on LMI. LMI control is a control method based on linear matrix inequalities. It designs the controller by solving a set of linear matrix inequalities to meet the performance requirements of the system, such as stability and robustness. It has strong advantages in multivariable systems and complex constraints. It can convert the performance indicators (such as quadratic performance indicators) and constraints (such as state constraints, control input constraints, etc.) of the control system into the form of linear matrix inequalities, and then solve them using effective numerical algorithms.

[0118] The state equation is:

[0119]

[0120] Where u is the control input, x = [x1 x2]';

[0121] A represents the system matrix, which describes the relationship between the state variables within the system; B is the input matrix, which describes how the input affects the state of the system; x1 and x2 represent state variables.

[0122] The controller is: u = Kx

[0123] Where K = [k1 k2], k1 and k2 are controller parameters.

[0124] The control objective is to achieve x→0,|u|≤u by designing LMI max ,

[0125] Controller Design:

[0126] Design Lyapunov function:

[0127] V=x'Px

[0128] V(0)=x'0Px0

[0129] Where P is a positive definite matrix and P>0, P=P'. Let F=KP -1 ,N=P -1 , The following five LMI formulas are obtained:

[0130] αN+AN+BF+NA'+F'B'<0

[0131]

[0132] P>0,P=P',→N>0,N=N'

[0133]

[0134] Using the above five LMI formulas, design the appropriate input u max , α, and find the effective K.

[0135] From the steady-state mathematical model of the RPC single-side converter, it can be seen that the intermediate DC side voltage The active power is related to the control phase angle δ, and the reactive power is mainly related to λ. The range is selected as δ<0.26rad, λ∈[0.6,1.0]. The DC side voltage and the reactive power on the α side, as well as the active and reactive components on the β side are input into the LMI controller to obtain the phase angles δ and λ, and then SPWM is used to adjust λ to control the voltage amplitude, and the voltage phase angle is controlled by the secondary side δ of the step-down transformer.

[0136] Phase detection is a method used to detect the phase difference between two signals. It is widely used in many fields such as electronic technology, communication engineering, and power systems. Its core is to compare the phase relationship between two signals of the same frequency and convert this phase difference information into physical quantities such as voltage and current that are easy to measure or process. According to the principle of phase detection, the load current amplitudes of the two arms are multiplied by their corresponding voltage synchronization signals, and the load currents of the two arms are deduced as:

[0137]

[0138] Finally, the average distribution of compensation current for each weight is obtained as follows:

[0139]

[0140] As a preferred solution of the traction power supply power management method based on HAPF and quadruple RPC described in the present invention, the lithium battery model selects the PNGV model. The model is constructed based on physical principles and can accurately reflect the changing relationship of multiple parameters such as voltage, current, temperature, etc. of the lithium battery during the charging and discharging process. Since the PNGV model has clear physical meaning, relatively simple parameter identification, and high fitting accuracy, it is adopted and studied by most researchers.

[0141] Combining the KVL law and the Nernst equation, the open circuit voltage and voltage drop can be obtained.

[0142]

[0143] In discharge state bat >0,V g 、V a , R d They are:

[0144]

[0145] When charging bat <0, R d 、V a 、V g They are:

[0146]

[0147] The variable S b and S g It is expressed as:

[0148]

[0149] In the above formula, V a Indicates V d The maximum saturation voltage drop, R0 is the internal resistance constant, S b For SOC to V g The impact point, V a0 V a Constant value, S b0 For S b Maximum value, similarly β g For S g The minimum value, S g0 is the maximum value of the corresponding curvature.

[0150] As a preferred solution of the traction power supply power management method based on HAPF and quadruple RPC described in the present invention, flywheel energy storage is applied in the electrified railway traction power supply system, and the traction power is compensated and controlled by charging and discharging to realize the recovery of regenerative braking energy. The core principle of flywheel energy storage is to convert electrical energy into mechanical energy and store it. When there is excess electrical energy, the motor drives the flywheel to rotate at high speed, and the flywheel stores the electrical energy in the form of kinetic energy. The kinetic energy calculation formula is: Where E k is the kinetic energy, I is the moment of inertia of the flywheel, and ω is the angular velocity of the flywheel.

[0151] The flywheel has acceleration and deceleration functions. By setting the threshold, the motor-side converter can be reasonably controlled according to the level of traction power to achieve the flywheel's motoring or generating conditions.

[0152] Since the present invention applies the flywheel to the traction power supply system, in order to reduce voltage conflicts, according to the quadruple topology, for a single module, the intermediate DC bus voltage reference value is set to 1800V, and the DC bus voltage is obtained by stepping down and converting the traction bus.

[0153] During the charging process, the flywheel speed increases. At this time, the performance analysis is carried out through its time consumption, power, current and other aspects. Its essence is the speed control of the motor rotor. The flywheel energy storage charging condition is actually a "speed-current" double closed-loop speed control, which uses speed as the outer loop and current as the inner loop control. PI regulation increases the acceleration to ensure that the motor reaches the peak quickly. The maximum speed is ω, and the corresponding reference speed is ω * , the error is sent to PI regulation to obtain That is, the actual speed tracks the rated speed.

[0154] The transfer function of the current loop is:

[0155]

[0156] The open-loop transfer function of the speed loop is:

[0157]

[0158] When the locomotive brakes, the traction motor uses feedback braking, which will send regenerative braking energy back to the traction network, causing a surge in DC voltage. The flywheel energy storage device is then charged faster, and this part of the energy is converted into kinetic energy of the high-speed rotating flywheel.

[0159] There are two points to consider in the discharge process of the flywheel, namely, stable voltage output and load power less than the rated value. Based on this, when the flywheel energy storage works in the discharge mode, in order to ensure the stability of the traction network voltage, the "voltage-current" dual closed-loop control is adopted, with voltage as the outer loop control and current as the inner loop. At this time, there is no need to consider the speed. With the actual voltage U dc The error is sent to the PI regulator as the given value of the current. Further, compared with the actual current i d The difference is made and the error is sent to the next PI controller for adjustment. The processed results of d and q are inversely transformed to the pulse generator, which outputs the corresponding PWM control signal, thereby driving the inverter to control the motor speed.

[0160] The closed-loop transfer function of the voltage loop is:

[0161]

[0162] When the locomotive starts, it will draw current from the traction network. Due to the existence of line impedance, the voltage of the traction network will drop. At this time, the flywheel energy storage device will slow down and discharge, and send back the previously stored electrical energy, which can effectively suppress the voltage drop and achieve recycling.

[0163] The main circuit of the train can be simplified to a three-level four-quadrant main circuit. It can be simplified using an equivalent model, and the equation is:

[0164]

[0165] is the voltage phase of the low voltage side, is the fundamental current phasor on the low voltage side, is the fundamental phasor of the PWM modulated voltage. The EMU control mode is PWM control. The amplitude is controlled by double closed-loop PI to adjust the phase, so that the fundamental power factor of the AC side meets the standard. Volatility Phase adjustment can keep the intermediate DC side power supply at a stable level.

[0166] As a preferred solution of the traction power supply power management method based on HAPF and quadruple RPC described in the present invention, the EMU control mode is PWM control, by The amplitude is controlled by double closed-loop PI to adjust the phase, so that the fundamental power factor of the AC side meets the standard. Volatility Phase adjustment can keep the intermediate DC side power supply at a stable level.

[0167] The traction converter is a power supply side converter, which is a rectifier during traction and an inverter during regenerative braking. The transient current direct control method is used to control the converter signal. The main steps of this scheme are as follows:

[0168]

[0169] when When the error ζ is equal to 0, PI regulation keeps the output constant and the power on the DC and AC sides of the rectifier is balanced; When the error ζ>0, the inner loop current of the PI regulation output will increase, and the input current and power of the rectifier will increase, so the inner loop current reflects the change in the required power.

[0170] Combining the locomotive model and traction power supply system, eight types of locomotive operating conditions are designed to conduct negative sequence and harmonic analysis on the grid side. The description of the eight types of operating conditions is shown in Table 2.

[0171] Table 2

[0172]

[0173]

[0174] Taking into account the actual operation of multiple trains, combined with the locomotive model and traction power supply system, the operating conditions of double train operation on the α side (one train traction and one train braking) and single train traction on the β side are designed.

[0175] As a preferred solution of the traction power supply power management method based on HAPF and quadruple RPC described in the present invention, the passive filter and the active filter are connected in series to form a series HAPF. Although the effect of the passive filter is not better than that of the active filter, the effect on fixed-order harmonics is still very obvious. The specific design is to connect a single passive filter in parallel and a high-pass filter in parallel at the same time, and use the circuit resonance principle to eliminate the 5th, 7th, and 11th harmonics. The parallel high-pass filter is used to eliminate the high-order harmonics generated by the switch.

[0176] Using circuit theory knowledge, it can be concluded that the n-order passive filter has a frequency of ω n =ω a The impedance Z n for:

[0177]

[0178] where ω a =2πf, f=50Hz, using the resonance principle we can get:

[0179]

[0180] By changing the formula, we can get the capacitance value as:

[0181]

[0182] The active filter mainly consists of a coupling transformer T, a DC capacitor C, a DC side reactor, and an output filter capacitor. The DC side capacitor mainly plays a role in voltage stabilization, and the strength of the effect is proportional to the size of the capacitor:

[0183]

[0184] Capacitors are passive components that do not consume energy, so the change in their value within a cycle is the size of the compensated capacitive reactive power:

[0185] ΔE(t)=Sk

[0186]

[0187] Where S is the compensation value. The DC side capacitor is set to 1100μF.

[0188] The output filter capacitor is composed of a main circuit of thyristors. Frequent switching actions are likely to produce high-frequency lines. In practice, a low-pass filter composed of a capacitor and an inductor can be connected in series before the filter to improve the quality of the output current. Its equivalent impedance is The traction power supply system uses fixed capacitors for reactive power compensation. The reactive power must be detected first, and the fixed compensation capacitor value can be designed based on the detected value. p -i q Improved method, using this method can simultaneously detect the harmonics and reactive current of the compensation system. p 、i q Corresponding to active and reactive currents, we have: Then we have:

[0189]

[0190] to i p -i q The method is to improve it to make it suitable for single-phase system. The specific method is to directly construct a virtual current perpendicular to the railway power supply system on its basis. h This is the harmonic current detected. Then it is passed into the active filter to achieve the suppression of system harmonics. q It is the reactive current. By detecting its value, the reactive value required by the traction power supply system can be calculated, and the size of the required fixed capacitance can be calculated based on the value.

[0191] In view of the harmonic problem of the above working conditions, HAPF is used for filtering, and the parameter settings are shown in Table 3:

[0192] Table 3 HAPF parameter settings

[0193]

[0194] In the experiment, the power of the two traction transformers of the present invention is 8×10 6 VA and 12.5×10 6 VA. The traction power supply system converts the input voltage into a voltage suitable for the load through two transformers with different turns ratios, and transmits the electric energy to the load through V / v wiring. This system design can effectively meet the power supply needs of traction motors in rail transit.

[0195] The present invention connects four RPCs in parallel to the traction power supply system, adopts limited LMI amplitude-phase control and introduces a hybrid energy storage device, including lithium batteries and flywheel energy storage, which can store and recycle electric energy while compensating for active, reactive and harmonic power, thus greatly saving energy. For the actual circuit of the locomotive, the control method adopts PWM control, and double closed-loop PI control is used to adjust the phase. The overall design process of the present invention can be: Step 1: Analyze the power quality problems of the traction power supply system; Step 2: Establish an engineering model of the traction power supply system and its key components; Step 3: Build a quadruple RPC model based on limited LMI amplitude-phase control, and introduce a hybrid energy storage device, including lithium batteries and flywheel energy storage; Step 4: Construct an EMU model and design 8 operating conditions; Step 5: Construct a HAPF model and adjust the parameters under multiple operating conditions; Step 6: Perform multi-operating condition power quality analysis on the traction power supply system. The corresponding flow chart is as follows: Figure 1 shown. Figure 2 It is the overall structural diagram of the present invention; Figure 3 This is a diagram of the RPC single-sided equivalent circuit model of the present invention; Figure 4 It is the control logic block diagram of both sides of RPC of the present invention;

[0196] Figure 5 This is a lithium battery model diagram of the present invention;

[0197] Figure 6 is a main circuit diagram of the train of the present invention;

[0198] Figure 7 This is a grid-side current waveform diagram of the present invention, showing the grid-side current waveform of the present invention at 0s-2s. The three-phase current fluctuates up and down when the locomotive operating conditions change.

[0199] Figure 8 The harmonic content of the grid-side current under 8 working conditions after HAPF filtering of the present invention is shown, which shows the relationship between the harmonic content and the harmonic order of the grid-side current under different working conditions after HAPF filtering. It can be seen that the harmonic content of each working condition is low after filtering.

[0200] Fig. 9The voltage waveform of the traction network side of the present invention is shown in Figure 2, which shows the voltage waveform of the traction network side of the present invention at 0s-2s. As can be seen from the figure, the instantaneous value of the traction network voltage is maintained at

[0201] Fig.10 The waveform diagram of the feeder current on the traction network side of the present invention shows the feeder current waveform on the α and β sides of the traction network of the present invention at 0s-2s. The feeder current waveform on the α and β sides fluctuates between 100A and 200A as the working conditions change.

[0202] Fig.11 The present invention selects four working conditions for the comparison of feeder current harmonic content on the traction network side, and displays the harmonic comparison diagram before and after HAPF filtering under the 1st, 2nd, 3rd, and 5th working conditions. The results show that after HAPF filtering, the feeder current harmonics on the traction network side are greatly reduced in low-order harmonics and 50-60th harmonics, and 90-99th harmonics are significantly reduced.

[0203] Fig.12 The present invention selects the voltage harmonic content comparison of 4 working conditions on the traction network side, and displays the harmonic comparison diagram before and after HAPF filtering under the 1st, 2nd, 3rd and 5th working conditions. The results show that after HAPF filtering, the voltage harmonics of the traction network are greatly reduced in low-order harmonics, and the 50th-60th harmonics and 90th-99th harmonics are slightly reduced.

[0204] Fig.13 This is the 0.2s-0.4s traction network side feeder current harmonic diagram of the present invention under the double-column traction condition. It shows the change of the traction network side feeder current harmonics within 10 cycles after filtering of the present invention. It can be found that its harmonic content is generally low, and it is proved that under the condition that the working condition remains unchanged, the effect of reducing harmonics is not unique in each cycle.

[0205] Fig.14 This is a locomotive side current waveform diagram of the present invention, showing the locomotive α side current waveform of the present invention at 0s-2s. The α side current waveform fluctuates as the operating conditions change.

[0206] Fig.15 It is the harmonic content of the locomotive side current under 8 working conditions before HAPF filtering of the present invention, showing the relationship between the harmonic content and the harmonic order of the locomotive side current under different working conditions before HAPF filtering.

[0207] Fig.16 The figure shows the harmonic content of the locomotive side current under eight working conditions after HAPF filtering, showing the relationship between the harmonic content and harmonic order of the locomotive side current under different working conditions after HAPF filtering. Fig.14 and Fig.15 By comparison, it can be seen that the overall harmonics of the locomotive side current are significantly reduced after HAPF filtering.

[0208] Fig.17 The present invention selects the harmonic content comparison of 4 working conditions on the locomotive side, and shows the harmonic comparison diagram before and after HAPF filtering under the 1st, 2nd, 3rd and 5th working conditions. The results show that after HAPF filtering, the 0-20th harmonics on the locomotive side are greatly reduced, and the 50-60th and 90-99th harmonics are significantly reduced.

[0209] Fig.18 This is a comparison diagram of the harmonics before and after the locomotive current is filtered under the conditions of one train pulling and one train braking on the α side and a single train pulling on the β side. The results show that the locomotive current harmonics are significantly reduced after filtering.

[0210] Fig.19 This is the FFT diagram of the locomotive current before filtering in working condition 4 of the present invention.

[0211] Fig. 20 This is the FFT diagram of the locomotive current after filtering in working condition 4 of the present invention.

[0212] according to Fig.19 and Fig. 20 By comparison, it can be seen that in working condition 4, the THD value of the locomotive current is greatly reduced after HAPF filtering.

[0213] The present invention also provides a computer-readable storage medium, which stores a computer program, and the computer program can be used to execute the above-mentioned traction power supply power management method based on HAPF and quadruple RPC. Computer-readable media include permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. The information can be a computer-readable instruction, a data structure, a module of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include temporary computer-readable media (transitory media), such as modulated data signals and carriers.

[0214] The present invention also provides a device corresponding to the traction power supply electric energy management method based on HAPF and quadruple RPC, including a processor, an internal bus, a network interface, a memory and a non-volatile memory, and of course may also include hardware required for other services. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the above method. Of course, in addition to the software implementation method, the present invention does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc., that is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0215] The controller can be implemented in any appropriate manner, for example, the controller can take the form of a microprocessor or processor and a computer-readable medium storing a computer-readable program code (such as software or firmware) that can be executed by the (micro)processor, a logic gate, a switch, an application-specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in a purely computer-readable program code manner, the controller can be implemented in the form of a logic gate, a switch, an application-specific integrated circuit, a programmable logic controller, and an embedded microcontroller by logically programming the method steps. Therefore, this controller can be considered as a hardware component, and the devices included therein for implementing various functions can also be regarded as structures within the hardware component. Or even, the devices for implementing various functions can be regarded as both software modules for implementing the method and structures within the hardware component.

[0216] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0217] For the convenience of description, the above device is described as being divided into various units according to their functions. Of course, when implementing the present invention, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0218] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0219] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0220] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0221] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0222] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0223] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0224] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A traction power supply power management method based on HAPF and quadruple RPC, characterized in that: The method comprises the following steps: Constructing an engineering model of a traction power supply system and its key components, wherein the traction power supply system and its key components include a three-phase power system and a traction transformer, wherein two power supply arms are connected to both sides of the secondary winding of the traction transformer, and the power supply arms are connected to the main circuit of the train; Connecting a quadruple RPC model based on limited LMI amplitude and phase control in parallel at both ends of the traction power supply system, wherein the busbar of the RPC model is connected to an energy storage device; The working conditions of the train are set, and the parameters of the hybrid active filter are set based on the working conditions. The hybrid active filter is arranged on the power supply arms on both sides of the traction power supply system to control the operation of the main circuit of the traction power supply system and the train under various working conditions.

2. According to claim 1, a traction power supply electric energy management method based on HAPF and quadruple RPC is characterized in that: The quadruple RPC model is four RPC modules connected in parallel, each RPC module includes a back-to-back converter, and the back-to-back converter is controlled by the total compensation current command signal of the corresponding RPC module, and the total compensation current command signal is: in, and Respectively represent the compensation current command signals of the converters corresponding to the two power supply arms, i' α and i' β is the compensated bilateral traction current, i αl and i βl Represents the load current of the two arms.

3. According to claim 2, a traction power supply electric energy management method based on HAPF and quadruple RPC is characterized in that: The compensated bilateral traction current is: Among them, I' p It represents the active current amplitude after active power transfer balance, ω is the angular frequency, and t represents time.

4. According to claim 2, a traction power supply electric energy management method based on HAPF and quadruple RPC is characterized in that: The RPC module is controlled by a voltage and current double closed loop, wherein the controller used for RPC amplitude and phase control is a limited controller based on LMI, and the state equation of the limited controller is: Where u is the control input, x = [x1 x2]'; A represents the system matrix, which describes the relationship between the state variables within the system; B is the input matrix, which describes how the input affects the state of the system; x1 and x2 represent state variables; The controller is: u=Kx Where K = [k1 k2], k1 and k2 are controller parameters; The control objective is to achieve x→0 by designing LMI. Among them, u max Indicates the maximum value of the control input, u max Indicates the maximum value of the control input change rate; Controller Design: Design Lyapunov function: V=x'Px V(0)=x'0Px0 Where P is a positive definite matrix and P>0, P=P', V represents the value of the Lyapunov function, V(0) represents the value of the Lyapunov function in the initial state, x0 represents the initial state variable of the system, let F=KP -1 ,N=P -1 , The following five LMI formulas are obtained: αN+AN+BF+NA'+F'B'<0 P>0,P=P',→N>0,N=N' Among them, α represents a given constant, N represents the inverse of the positive definite matrix, Represents a positive number. Using the above five LMI formulas, design an appropriate input u max , α, and find the effective K.

5. According to claim 1, a traction power supply electric energy management method based on HAPF and quadruple RPC is characterized in that: The energy storage device comprises a lithium battery energy storage part and a flywheel energy storage part.

6. The traction power supply power management method based on HAPF and quadruple RPC according to claim 5 is characterized in that: When the lithium battery energy storage part is in the discharge state, bat >0,V g 、V a , R d They are: When charging bat <0, R d 、V a 、V g They are: Among them, V g 、V a , R d They represent the charging voltage tail rise, the maximum saturation voltage drop, and the battery discharge internal resistance, V a0 Indicates V a Constant value, V a1 Indicates V a Coefficient of variation, SOC represents the state of charge, S a For SOC to V a The impact point, S b For SOC to V g The influence point, R0 represents the internal resistance constant, R1 represents the internal resistance variation coefficient, S d represents the threshold state of charge, i bat Represents the battery current, R c Represents the charging internal resistance, V ga Indicates the charging voltage coefficient.

7. The traction power supply power management method based on HAPF and quadruple RPC according to claim 5 is characterized in that: The flywheel energy storage part adopts speed-current dual closed-loop speed control when in charging state, and adopts voltage-current dual closed-loop control when in discharging state; The transfer function of the current loop in the speed-current dual closed-loop speed control is: Among them, s is the Laplace operator, T is the time constant, and K is the proportional coefficient; The open-loop transfer function of the speed loop is: Among them, K m Represents the torque constant, K t is the back electromotive force constant, τ m represents the electromechanical time constant, J represents the moment of inertia, T s represents the time constant; The closed-loop transfer function of the voltage loop in the voltage-current dual closed-loop control is: Among them, T u represents the time constant of the voltage loop, C d Represents the DC bus capacitance, T q Represents electromagnetic torque, K up Represents the proportional gain of the voltage loop.

8. The traction power supply power management method based on HAPF and quadruple RPC according to claim 1 is characterized in that: The hybrid active filter is a passive filter and an active filter connected in series; The nth order passive filter at frequency ω n =ω a The impedance Z n for: Among them, R n represents the nth passive filter resistance, ω a represents the frequency of the passive filter of order a (a is a positive integer), ω n represents the nth passive filter frequency, L n represents the nth order passive filter inductance, C n represents the passive filter capacitance of n times; The capacitive reactive power of the DC side capacitor compensation of the active filter is: ΔE(t)=Sk Among them, ΔE(t) represents the change value of the capacitance within one cycle, S represents the compensation size, k represents the transformation ratio, C represents the DC side capacitance, and ΔU m Indicates the voltage fluctuation range, U * m Indicates the regulated voltage value.

9. A traction power supply power management system based on HAPF and quadruple RPC, comprising a memory, a processor, and a program stored in the memory, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed, the method according to any one of claims 1 to 8 is implemented.

Images