Energy management method of flexible DC traction power supply system based on superposition circuit

Abstract

The present application discloses an energy management method for a flexible DC traction power supply system based on a superposition circuit, wherein the method includes: obtaining the traction station port voltage and the traction station rail potential of the flexible DC traction power supply system; decomposing the traction station load current from the traction station current, decomposing the traction station rail potential to obtain the traction station rail potential load component from the traction station rail potential, and calculating the traction station coordinated current reference value based on the traction station load current and the rail potential load component, and calculating the traction station voltage reference value based on the traction station coordinated current reference value; generating a traction station voltage reference instruction and a traction station current reference instruction based on the traction station coordinated current reference value and the traction station voltage reference value, and controlling the power supply system according to the traction station voltage reference instruction and the current reference instruction. In this way, the locomotive regenerative braking energy is effectively absorbed, the rail potential is reduced, the system reliability is ensured, and a technical solution is provided for the actual operation control of the flexible DC traction power supply technology for rail transit.

Description

Technical Field

[0001] The present application relates to the technical field of electrical automation of rail engineering, and in particular to an energy management method, device, electronic equipment and storage medium for a flexible DC traction power supply system based on a superposition circuit. Background Art

[0002] Flexible DC traction power supply systems, with their flexibility and controllability, can largely overcome the shortcomings of diode rectifier and energy-feed power supply systems, making them a key future development trend. These systems can reduce system construction costs, improve power quality, flexibly regulate voltage, and facilitate integration with renewable energy. Through system-level energy management, they can improve the utilization of locomotive regenerative braking energy, reduce network losses, and lower rail voltage. However, the rapid development of urban rail transit has posed new challenges to its traction power supply systems. With the rapid growth in the carrying capacity and mileage of urban rail transit systems such as subways and light rail, the power consumption of DC traction power supply systems has increased rapidly, leading to rising electricity costs for subway operations and the risk of exceeding rail voltage standards. To support green development and ensure the safe and reliable operation of subway systems, there is an urgent need to improve the energy efficiency of DC traction power supply systems.

[0003] Currently, there is limited research on energy management methods for flexible DC traction power supply schemes. However, energy management methods play a vital role in the economical, energy-saving, safe and reliable operation of the system. Therefore, it is necessary to study energy management methods for flexible DC traction power supply systems to effectively coordinate all traction substations in the control system. Summary of the Invention

[0004] The present application provides an energy management method, device, electronic device and storage medium for a flexible DC traction power supply system based on a superposition circuit. It does not require real-time communication or measurement of locomotive information, has a small amount of calculation, can effectively reduce the operating cost of the DC traction power supply system, improve the utilization rate of locomotive regenerative braking energy, reduce the rail potential, and provide a technical solution for the actual operation control of flexible DC traction power supply technology for rail transit.

[0005] A first aspect of the present application provides an energy management method for a flexible DC traction power supply system based on a superposition circuit, comprising the following steps: obtaining a traction station port voltage, a traction station rail potential, and a traction station current of the flexible DC traction power supply system; decomposing the traction station current to obtain a traction station load current, and decomposing the traction station rail potential to obtain a traction station rail potential load component, and calculating a traction station coordinated current reference value based on the traction station load current and the traction station rail potential load component, and calculating a traction station voltage reference value based on the traction station coordinated current reference value; generating a traction station voltage reference instruction and a traction station current reference instruction based on the traction station coordinated current reference value and the traction station voltage reference value, and controlling the power supply of the flexible DC traction power supply system according to the traction station voltage reference instruction and the traction station current reference instruction.

[0006] Optionally, in one embodiment of the present application, the decomposition of the traction station current to obtain the traction station load current, and the decomposition of the traction station rail potential to obtain the traction station rail potential load component, include: based on the circuit superposition principle, splitting the flexible DC traction power supply system into a load subsystem and a cooperative subsystem, and performing equivalent transformation on the load and traction station in the flexible DC traction power supply system, and decomposing the traction station voltage into common-mode voltage and differential-mode voltage; setting the current source and voltage source in the load subsystem and the cooperative subsystem and performing circuit calculation to decompose the traction station current into the traction station load current and the traction station cooperative current, and decomposing the traction station rail potential into the traction station rail potential load component and the traction station rail potential cooperative component.

[0007] Optionally, in one embodiment of the present application, generating the traction station current reference instruction includes: when the traction station load current of any traction station in the flexible DC traction power supply system is greater than or equal to a preset traction station current limit value, selecting at least one traction station from the other traction stations for support according to a first preset condition to transfer the load current of the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the traction station load current of any traction station in the flexible DC traction power supply system is less than the traction station power lighting load current, selecting at least one traction station from the other traction stations for support according to a second preset condition to absorb the regenerative braking current of the locomotive near the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the rail potential at any traction station in the flexible DC traction power supply system exceeds the preset traction station rail potential limit value, selecting at least one traction station from the other traction stations for support according to a third preset condition to adjust the rail potential distribution, wherein the sum of the coordinated current reference instructions of the traction stations providing support is zero.

[0008] Optionally, in one embodiment of the present application, generating the traction station voltage reference instruction includes: based on the split flexible DC traction power supply system, generating the traction station voltage reference instruction according to the branch voltage vector in the collaborative subsystem and the branch current vector in the collaborative subsystem, as well as the common mode voltage and the differential mode voltage.

[0009] The second aspect of the present application provides an energy management device for a flexible DC traction power supply system based on a superposition circuit, including: an acquisition module for acquiring the traction station port voltage, the traction station rail potential and the traction station current of the flexible DC traction power supply system; a calculation module for decomposing the traction station current to obtain the traction station load current, decomposing the traction station rail potential to obtain the traction station rail potential load component, and calculating the traction station coordinated current reference value based on the traction station load current and the traction station rail potential load component, and calculating the traction station voltage reference value based on the traction station coordinated current reference value; a management module for generating a traction station voltage reference instruction and a traction station current reference instruction based on the traction station coordinated current reference value and the traction station voltage reference value, and controlling the power supply of the flexible DC traction power supply system according to the traction station voltage reference instruction and the traction station current reference instruction.

[0010] Optionally, in one embodiment of the present application, the calculation module is specifically used to, based on the circuit superposition principle, split the flexible DC traction power supply system into a load subsystem and a cooperative subsystem, and perform equivalent transformation on the load and traction station in the flexible DC traction power supply system, and decompose the traction station voltage into common-mode voltage and differential-mode voltage, and perform circuit calculation after setting the current source and voltage source in the load subsystem and the cooperative subsystem to decompose the traction station current into the traction station load current and the traction station cooperative current, and decompose the traction station rail potential into the traction station rail potential load component and the traction station rail potential cooperative component.

[0011] Optionally, in one embodiment of the present application, the management module is specifically configured to: when the traction station load current of any traction station in the flexible DC traction power supply system is greater than or equal to a preset traction station current limit value, select at least one traction station from the other traction stations for support according to a first preset condition to transfer the load current of the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the traction station load current of any traction station in the flexible DC traction power supply system is less than the traction station power lighting load current, select at least one traction station from the other traction stations for support according to a second preset condition to absorb the regenerative braking current of the locomotive near the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the rail potential at any traction station in the flexible DC traction power supply system exceeds the preset traction station rail potential limit value, select at least one traction station from the other traction stations for support according to a third preset condition to adjust the rail potential distribution, wherein the sum of the coordinated current reference instructions of the traction stations providing support is zero.

[0012] Optionally, in one embodiment of the present application, the management module is specifically used to generate the traction station voltage reference instruction based on the split flexible DC traction power supply system, according to the branch voltage vector in the collaborative subsystem and the branch current vector in the collaborative subsystem, as well as the common mode voltage and the differential mode voltage.

[0013] An embodiment of the third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored on the memory and runnable on the processor, wherein the processor executes the program to perform the energy management method of the flexible DC traction power supply system based on the superposition circuit as described in the above embodiment.

[0014] The fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to perform the energy management method of a flexible DC traction power supply system based on a superposition circuit as described in the above embodiment.

[0015] The embodiments of the present application have the following beneficial effects:

[0016] 1) Control parameters are easy to adjust. It is only necessary to determine the voltage fluctuation range of the traction station, and no other control parameters need to be adjusted.

[0017] 2) Without measuring locomotive information, the system calculates the natural distribution of locomotive energy demand across traction depots, providing a rough estimate of the load. This load information allows for targeted coordinated control of traction depots, absorbing regenerative energy and preventing converter current limits.

[0018] 3) The rail potential can be reduced through coordinated control of the traction station.

[0019] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0021] Figure 1 A flow chart of an energy management method for a flexible DC traction power supply system based on a superposition circuit provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of the architecture of the flexible DC traction power supply system and its energy management method provided in an embodiment of the present application;

[0023] Figure 3 A schematic diagram of the upper-layer collaborative control process provided in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of an equivalent method of the original system based on a superposition circuit provided in an embodiment of the present application;

[0025] Figure 5 Schematic diagram of rail potential modeling and calculation provided in the embodiments of this application;

[0026] Figure 6 A schematic diagram of an equivalent method for a controlled system based on a superposition circuit provided in an embodiment of the present application;

[0027] Figure 7 This is an example diagram of an energy management device for a flexible DC traction power supply system based on a superposition circuit according to an embodiment of the present application;

[0028] Figure 8 A schematic diagram of the structure of an electronic device provided in an application embodiment. DETAILED DESCRIPTION

[0029] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0030] In the energy management of flexible DC traction power supply systems, the technical solutions in related technologies are based on droop control methods or optimal control methods commonly used in flexible DC grids. Droop control methods have difficulty determining control parameters in low-voltage DC traction power supply systems with limited voltage fluctuations. A large droop coefficient can cause the system voltage fluctuation range to be excessive, exceeding the allowable voltage range; a small droop coefficient cannot effectively achieve power transfer between traction stations. Furthermore, droop control schemes do not reduce rail potential. When equipment power reaches capacity constraints, droop control schemes lose their ability to control voltage, which is not conducive to ensuring system power supply reliability in the event of a fault. Optimal control methods require all real-time information, including locomotive information, and the optimal control algorithm is computationally intensive, with the computational complexity proportional to the cube of the number of system nodes. Optimal control methods place excessively high demands on the computational speed of the traction power supply system's computing system and the real-time performance of the signaling system, making them difficult to apply to real-time control.

[0031] Based on the above problems, this application proposes a flexible DC traction power supply system energy management method based on a superposition circuit, targeting the specific characteristics of the flexible DC traction power supply system. It can achieve fast real-time control according to different control target combinations. This method does not require the collection of real-time locomotive information and has low requirements for the signal system. It has a fast calculation speed, and the amount of calculation for each control is proportional to the first power of the number of traction stations, which is much less than the optimal control method. It can reduce the peak current or peak power of the converter, absorb the regenerative braking energy of the locomotive, and reduce the potential of the rails, significantly improving the reliability, economy and energy-saving benefits of the system operation.

[0032] Specifically, Figure 1 A flow chart of an energy management method for a flexible DC traction power supply system based on a superposition circuit provided in an embodiment of the present application.

[0033] like Figure 1 As shown, the energy management method of the flexible DC traction power supply system based on the superposition circuit includes the following steps:

[0034] In step S101, the port voltages, rail potentials, and currents of all traction stations of the flexible DC traction power supply system are obtained.

[0035] like Figure 2 As shown, the flexible DC traction power supply system includes N traction substations, and each traction substation includes k bidirectional converters.

[0036] First, based on the measurement system, all N traction converter measurement values ​​are obtained, where the measurement value of the i-th traction station includes the traction station port voltage U si , traction current I si , traction rail potential Uwi , and the signal system sends the measured value of the traction station to the upper collaborative controller. If the k bidirectional converters in the ith traction station are partially out of service, the traction station port voltage U si , traction current I si , traction rail potential U w If the ith traction station is disconnected, continue to collect the traction station port voltage U si , and the traction rail potential U w .

[0037] Secondly, the upper-level collaborative controller calculates the voltage reference command and current reference command of N traction substations based on the measured values ​​of N traction converters. refi , I refi They represent the voltage reference command and current reference command of the i-th traction station respectively.

[0038] Secondly, the voltage reference instructions and current reference instructions of the N traction substations are sent to the local converter controllers of the corresponding traction substations through the signal system.

[0039] It should be noted that during the control process, the upper-level collaborative controller needs to meet the control objectives and their combinations as much as possible under the constraints of the system voltage constraint, the traction station current constraint or power constraint, and the traction station rail potential constraint.

[0040] Different control objectives can be adopted for different power supply systems and different operating modes. The basic control objectives are: reducing the peak current or peak power of the converter, that is, actively limiting the peak current or peak power of the converter; absorbing the regenerative braking energy of the locomotive, that is, improving the economy of the system by absorbing the regenerative braking energy of the locomotive; and reducing the rail potential to ensure safe and reliable operation. In the normal operation mode of the traction power supply system using a distributed external power source, the control objectives are to reduce the peak current or peak power of the converter, absorb the regenerative braking energy of the locomotive, and reduce the rail potential; in the fault operation mode of the traction power supply system using a distributed external power source, the control objectives are to reduce the peak current or peak power of the converter and reduce the rail potential; in the normal operation mode of the traction power supply system using a centralized external power source, the control objectives are to reduce the peak current or peak power of the converter and reduce the rail potential; in the fault operation mode of the traction power supply system using a centralized external power source, the control objectives are to reduce the peak current or peak power of the converter and reduce the rail potential.

[0041] In step S102, the traction station load current is obtained by decomposing the traction station current, and the traction station rail potential is decomposed into the rail potential load component. The traction station coordinated current reference value is calculated based on the traction station load current and the rail potential load component, and the traction station voltage reference value is calculated based on the traction station coordinated current reference value.

[0042] Specifically, the traction station load current is obtained by decomposing the traction station current, and I svi Represents the load current of the i-th traction station; the rail potential load component of the traction station is obtained by decomposing the rail potential of the traction station, and is expressed as U wvi Indicates the rail potential load component of the i-th traction station; and calculates the reference value of the traction station coordinated current based on the traction station load current and the traction station rail potential load component, using I rci Indicates the reasonable coordinated current value achieved after the control of the ith traction station; the traction station voltage reference value is calculated based on the coordinated current reference value of the traction station, and U refi Represents the voltage reference value of the i-th traction station.

[0043] In the embodiments of the present application, Figure 3 As shown, it is necessary to measure the current and voltage of all traction stations, using U s and I s They represent the measured voltage vector and current vector of the traction station, that is, U s =[U s1 , U s2 ,…U si ,…U sN ] T , I s =[I s1 , I s2 ,…I si ,…I sN ] T . Use U w Represents the measured rail potential vector of the traction station, that is, U w =[U w1 , U w2 ,…U wi ,…U wN ] T Based on the signal system, the current, voltage and rail potential information of all traction stations are collected. w 、U s and I s As input, three core operations are performed: 1) The traction current is decomposed into the load current vector I based on the system modeling method sv and the coordinated current vector I sc Based on the system modeling method, the rail potential of the traction station is decomposed into the load component vector U wv and the cooperative component vector Uwc , based on the load current, the locomotive load information can be estimated, where I sv =[I sv1 , I sv2 ,…I svi ,…I svN ] T , I sc =[I sc1 , I sc2 ,…I sci ,…I scN ] T , I sci represents the coordinated current of the ith traction station, U wv =[U wv1 , U wv2 ,…U wvi ,…U wvN ] T , U wc =[U wc1 , U wc2 ,…U wci ,…U wcN ] T , U wci represents the rail potential coordination component of the i-th traction station; 2) based on the load current I calculated in step 1 sv and rail potential load component U wv , calculate the reasonable cooperative current value vector I rc , where I rc =[I rc1 , I rc2 ,…I rci ,…I rcN ] T , I rci It represents the reasonable cooperative current value achieved after the control of the ith traction, based on the cooperative current value I rc , the traction stations can effectively coordinate and support each other; 3) According to the coordinated current value I calculated in step 2 rc , calculate the traction substation voltage reference value vector U ref , U ref =[U ref1 , U ref2 ,…U refi ,…U refN ] T . Coordinated control output voltage reference value U ref The signal system transmits it to the converter controller of each traction station. The converter controller controls the converter in each traction station to operate according to the voltage command.

[0044] After the traction station voltage and traction station current of the flexible DC traction power supply system are obtained by measurement, the traction station load current is decomposed from the traction station current, and the traction station rail potential load component is decomposed from the traction station rail potential. As a specific implementation method, the traction station load current is decomposed from the traction station current, including: based on the circuit superposition principle, the flexible DC traction power supply system is split into a load subsystem and a cooperative subsystem, and the load and traction station in the flexible DC traction power supply system are equivalently transformed, and the traction station voltage is decomposed into a common-mode voltage and a differential-mode voltage; the current source and voltage source in the load subsystem and the cooperative subsystem are set and then circuit calculation is performed to decompose the traction station current into the traction station load current and the traction station cooperative current, and decompose the traction station rail potential into the rail potential load component and the rail potential cooperative component.

[0045] The traction load current and rail potential load components are decomposed by the superposition network, such as Figure 4 As shown in the figure, the original system is decomposed into the load subsystem and the cooperative subsystem. Assume that the locomotive is the current source and the traction station is the voltage source; the traction station voltage can be decomposed into common mode voltage and differential mode voltage, and U sg and ΔU si represent the common-mode voltage and differential-mode voltage of the i-th traction station, respectively. In the load subsystem, only the current source representing the locomotive energy demand and the voltage source representing the common-mode voltage of the traction station are retained; in the cooperative subsystem, only the voltage source representing the differential-mode voltage of the traction station is retained. Because the traction stations in the load subsystem all have the same voltage, the load subsystem's power flow distribution reflects the natural distribution of locomotive energy demand across traction stations. Because the cooperative subsystem only retains the voltage differences between traction stations, its power flow distribution reflects the effectiveness of cooperative control.

[0046] like Figure 4 As shown in (a), for the jth rail vehicle, it is assumed that the vehicle current is I vj . Figure 4 (a) is equivalent to Figure 4 (b), the voltage of the ith traction station is decomposed into the common mode voltage U sg and differential mode voltage ΔU si In the load subsystem, such as Figure 4 (c), the current of the traction station is the load current I svi ; In the collaborative subsystem, such as Figure 4 (d), the current of the traction station is the coordinated current I sci . Use U sg , ΔU s Represent the common mode voltage U of the traction station sg Vector, differential mode voltage ΔU si vector, i.e., U sg =[U sg,…U sg ,…U sg ] T , ΔU s =[ΔU s1 , ΔU s2 ,…ΔU si ,…ΔU sN ] T . Common mode voltage U sg It can be any value. In order to reduce the amount of calculation, the voltage U of the Nth traction station is selected. sN is the common mode voltage U sg .

[0047] According to the superposition principle:

[0048] ΔU s =U s -U sg (1)

[0049] Based on Kirchhoff's voltage law:

[0050]

[0051] Among them, U cb Represents the branch voltage vector in the cooperative subsystem, that is, U cb =[U cb1 , U cb2 ,…U cbi ,…U cb(N-1) ] T , U cbi Represents the branch voltage between the i-th traction station and the (i+1)-th traction station.

[0052] Define the admittance matrix G:

[0053] G=diag(r1 -1 ,r2 -1 ,K,r N-1 -1 ) (3)

[0054] Among them, r i Represents the resistance between the i-th traction station and the i+1-th traction station.

[0055] I cb =GU cb (4)

[0056] Among them, I cb Represents the branch current vector in the cooperative subsystem, that is, I cb =[I cb1 , I cb2 ,…I cbi ,…I cb(N-1) ]T , I cbi Represents the branch current between the i-th traction station and the (i+1)-th traction station.

[0057] From Kirchhoff's current law:

[0058]

[0059] According to the superposition principle:

[0060] I sv =I s -I sc (6)

[0061] Thus, the calculation of the traction load current is completed.

[0062] For the ith traction station, its ground conductivity is g wi . The rail potential calculation model of the collaborative subsystem based on the centralized parameter modeling method, such as Figure 5 As shown in (a). Ignoring the stray current to the ground, Figure 5 (a) is equivalent to Figure 5 The simplified calculation model in (b) is shown in Figure 2. In the collaborative subsystem, Figure 5 (a), the traction rail potential is the synergistic component U wci Assume that the contact network resistance and rail resistance between traction station i and traction station i+1 are r qi and r hi , the longitudinal pressure drop of the contact network and the longitudinal pressure drop of the rail are U qci and U hci . Use U qc , U hc They represent the longitudinal voltage drop vector of the contact network in the cooperative subsystem and the longitudinal voltage drop vector of the rail in the cooperative subsystem, namely U qc =[U qc1 , U qc2 ,…U qci ,…U qc(N-1) ] T , U hc =[U hc1 , U hc2 ,…U hci ,…U hc(N-1) ] T .

[0063] According to the superposition principle:

[0064] U w =U wc +U wv (7)

[0065] Based on Kirchhoff's current law:

[0066]

[0067] Based on Kirchhoff's current law:

[0068]

[0069] Find U wc1 , and thus the coordinated component of the entire rail potential can be obtained from (8) (9):

[0070]

[0071] Depend on

[0072] U wv =U w -U wc (13)

[0073] The potential load component of the traction rail can be calculated.

[0074] In step S103, a traction station voltage reference instruction and a traction station current reference instruction are generated according to the traction station coordinated current reference value and the traction station voltage reference value, and the power supply of the flexible DC traction power supply system is controlled according to the traction station voltage reference instruction and the traction station current reference instruction.

[0075] Optionally, in one embodiment of the present application, generating a traction station current reference instruction includes: when the traction station load current of any traction station in the flexible DC traction power supply system is greater than or equal to a preset traction station current limit value, selecting at least one traction station from the other traction stations for support according to a first preset condition to transfer the load current of the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the traction station load current of any traction station in the flexible DC traction power supply system is less than the traction station power lighting load current, selecting at least one traction station from the other traction stations for support according to a second preset condition to absorb the regenerative braking current of the locomotive near the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the rail potential at any traction station in the flexible DC traction power supply system exceeds the preset traction station rail potential limit value, selecting at least one traction station from the other traction stations for support according to a third preset condition to adjust the rail potential distribution, wherein the sum of the coordinated current reference instructions of the traction stations providing support is zero.

[0076] Optionally, in one embodiment of the present application, generating a traction station voltage reference instruction includes: based on the split flexible DC traction power supply system, generating a traction station voltage reference instruction according to the branch voltage vector in the collaborative subsystem and the branch current vector in the collaborative subsystem, as well as the common mode voltage and the differential mode voltage.

[0077] After obtaining the traction load current, calculate the reference value of the coordinated current under normal operation mode.

[0078] and Figure 4 Unlike the measurement-based systems shown, Figure 6 Shown is the system after being charged. Figure 6 In (a), for the ith traction station, its voltage and current are U refi and I refi . Figure 6 (a) is equivalent to Figure 6 (b), the voltage of the ith traction station is decomposed into the common mode voltage U rg and differential mode voltage ΔU ri In the controlled load subsystem, such as Figure 6 (c), the current of the traction station is still Figure 4 The load current I in (c) svi ; In the controlled collaborative subsystem, such as Figure 6 (d), the current of the traction station is the coordinated current I rci . Use U rg , ΔU r Represent the common mode voltage U of the traction station rg Vector, differential mode voltage ΔU ri Vector, namely U rg =[U rg ,…U rg ,…U rg ] T , ΔU r =[ΔU r1 , ΔU r2 ,…ΔU ri ,…ΔU rN ] T , common mode voltage U rg It can be any value. In order to reduce the amount of calculation, the voltage U of the Nth traction station is selected. refN is the common mode voltage U rg .

[0079] According to the known load current of the traction station, the ideal coordinated current reference instruction can be determined. svi Exceeds the traction current limit value I limi ,

[0080] I rci =I limi -I svi (14)

[0081] Its load current needs to be transferred to the nearby traction station. The nearby traction station provides current support to the i-th traction station to prevent the current of the i-th traction station from exceeding the limit value. The coordinated current reference instruction of the traction station providing support is consistent with the coordinated current reference instruction I of the i-th traction station. rci The sum is 0. When more than one traction station provides coordinated current support to a certain traction station at the same time, the magnitude of the coordinated current of the supporting traction station is inversely proportional to the impedance between it and the supported traction station, that is, the closer the traction station is to the supported traction station, the more coordinated current support it provides.

[0082] If the load current I svi Less than the traction power lighting load current I sali :

[0083] I rci = -I sali -I svi (15)

[0084] Its feedback current needs to be transferred to the nearby traction station. The nearby traction station absorbs the regenerative braking current of the locomotive near the i-th traction station to avoid the current of the i-th traction station being fed back to the AC grid, and realizes the absorption of the locomotive regenerative braking energy within the DC traction power supply system. The coordinated current reference instruction of the supporting traction station and the coordinated current reference instruction I of the i-th traction station are rci The sum is 0. When more than one traction station provides coordinated current support to a certain traction station at the same time, the magnitude of the coordinated current of the supporting traction station is inversely proportional to the impedance between it and the supported traction station, that is, the closer the traction station is to the supported traction station, the more coordinated current support it provides.

[0085] If the rail potential load component U of the traction station of the i-th traction station wvi Exceeding the limit value U wlim :

[0086] U wci =U wlim -U wvi (16)

[0087] The nearby traction needs to change the coordinated current reference instruction I rc To change the rail longitudinal pressure drop U hc , thereby changing the longitudinal distribution of rail potential and preventing the rail potential amplitude from being too high in some local areas. wci , select a nearby traction station j, and change the longitudinal voltage drop of the rail through the cooperative current between traction station j and traction station j+1:

[0088]

[0089] The sum of the coordinated current reference commands for the supporting traction depot is 0. The above describes the calculation method for the coordinated current reference value under normal operation in a traction power supply system using a distributed external power source. In fault operation, due to the short duration of the fault, the economic operation of the system can be temporarily ignored: that is, only the current limit of the traction depot and the limitation of the rail potential can be considered, and the absorption of the locomotive regenerative braking energy can be temporarily ignored.

[0090] In a traction power supply system using a distributed external power source, it is necessary to consider the current limitation of the traction station, the limitation of the rail potential, and the absorption of the locomotive regenerative braking energy; in a traction power supply system using a centralized external power source, it is not necessary to consider the absorption of the locomotive regenerative braking energy, and only the safe and reliable operation of the system needs to be ensured.

[0091] Calculate the voltage reference command of the traction station. In the controlled system, if Figure 6 As shown, use U rb Represents the branch voltage vector in the cooperative subsystem, that is, U rb =[U rb1 , U rb2 ,…U rbi ,…U rb(N-1) ] T , U rbi I represents the branch voltage between the i-th traction station and the (i+1)-th traction station after control. rb Represents the branch current vector in the cooperative subsystem, that is, I rb =[I rb1 , I rb2 ,…I rbi ,…I rb(N-1) ] T , I rbi Represents the branch current between the i-th traction station and the (i+1)-th traction station after control.

[0092] From Kirchhoff's current law:

[0093]

[0094] Define the matrix R:

[0095] R=diag(r1,r2,K,r N-1 ) (19)

[0096] It can be calculated

[0097] U rb =RI rb (20)

[0098] Based on Kirchhoff's voltage law:

[0099]

[0100] By specifying the common mode voltage U of the traction after being controlled rg , we can calculate:

[0101] U ref =U rg +ΔU r (twenty two)

[0102] In order to ensure that the voltage of all traction stations is within a reasonable range, the common mode voltage U rg Should be around the rated value:

[0103] I ref =I sv +I rc (twenty three)

[0104] It should be noted that the energy management method of the above embodiment may adopt a centralized control method or a distributed control method with partitioning, grading or grouping in actual application.

[0105] Furthermore, the embodiments of the present application may use a combination of an energy management method for ensuring that the current of the traction station does not exceed the limit, an energy management method for absorbing the regenerative energy of the locomotive, and an energy management method for reducing the potential of the rails, or one or two of these methods may be selected for use. All three energy management methods will have an impact on the voltage and current instructions of the traction station. When more than one energy management method is used at the same time, the control instructions may conflict. Among them, the energy management method for ensuring that the current of the traction station does not exceed the limit is conducive to absorbing the regenerative energy of the locomotive. Therefore, there is no conflict between the energy management method for ensuring that the current of the traction station does not exceed the limit and the energy management method for absorbing the regenerative energy of the locomotive. However, the energy management method for reducing the potential of the rails is not conducive to ensuring that the current of the traction station does not exceed the limit and absorbing the regenerative energy of the locomotive. Therefore, there is a conflict between the energy management method for reducing the potential of the rails and the energy management method for ensuring that the current of the traction station does not exceed the limit, and between the energy management method for reducing the potential of the rails and the energy management method for absorbing the regenerative energy of the locomotive.

[0106] When control commands conflict, a priority can be selected based on actual needs. For example, when three energy management methods are used simultaneously, the voltage command for the traction station can be calculated based on the energy management method that ensures the traction station current does not exceed the limit, ensuring that the traction station current is limited and ensuring equipment safety. Then, without affecting the traction station current limit, the traction station can be selected to generate a coordinated current, changing the rail potential distribution. The energy management method for reducing rail potential can be used to limit the locally excessive rail potential and avoid the operation of the rail potential limiter, which would cause large stray currents. Finally, the energy management method for absorbing locomotive regenerative energy can be used to further adjust the traction station coordinated current in areas that do not affect the traction station current limit and rail potential limit, reducing the return of locomotive regenerative braking energy to the urban distribution network and achieving an economical and energy-saving control effect.

[0107] If a current source converter is used instead of a voltage source converter in a traction station, the energy management method of the embodiment of the present application is also applicable. It is only necessary to directly use the current reference command to control the current source converter in the traction station, without having to calculate the voltage reference command of the traction station based on the current reference command.

[0108] The traction station current limit value in the embodiment of the present application can be either a constant value or updated in real time. Therefore, the present application is also applicable to the scenario of traction station power limit: the traction station current limit value is updated in real time based on the power limit value divided by the traction station voltage, thereby achieving traction station power limit.

[0109] According to the energy management method of the flexible DC traction power supply system based on the superposition circuit proposed in the embodiment of the present application, the original system is decomposed into a load subsystem and a cooperative subsystem. The power flow distribution of the load subsystem reflects the natural distribution of the locomotive energy demand among the traction depots, and characterizes the uncontrollable part of the original system. The power flow distribution of the cooperative subsystem reflects the effect of cooperative control and characterizes the controllable part of the original system. Based on the load subsystem in the modeling method, the load information can be estimated without directly measuring the locomotive load information, helping the energy management method to achieve targeted coordinated control. The method effectively utilizes the cooperative current of the traction depot of the cooperative subsystem, and calculates a reasonable cooperative current value to achieve the purpose of absorbing the regenerative braking energy of the locomotive and preventing the converter current from exceeding the limit.

[0110] Next, a flexible DC traction power supply system energy management device based on a superposition circuit proposed in an embodiment of the present application is described with reference to the accompanying drawings.

[0111] Figure 6 This is an example diagram of an energy management device for a flexible DC traction power supply system based on a superposition circuit according to an embodiment of the present application.

[0112] like Figure 6As shown, the energy management device 10 of the flexible DC traction power supply system based on the superposition circuit includes: an acquisition module 100, a calculation module 200 and a management module 300.

[0113] The acquisition module 100 is used to obtain the traction station port voltage, traction station rail potential, and traction station current of the flexible DC traction power supply system. The calculation module 200 is used to decompose the traction station current to obtain the traction station load current, decompose the traction station rail potential to obtain the traction station rail potential load component, calculate the traction station coordinated current reference value based on the traction station load current and the traction station rail potential load component, and calculate the traction station voltage reference value based on the traction station coordinated current reference value. The management module 300 is used to generate the traction station voltage reference command and the traction station current reference command based on the traction station coordinated current reference value and the traction station voltage reference value, and control the power supply of the flexible DC traction power supply system according to the traction station voltage reference command and the traction station current reference command.

[0114] Optionally, in one embodiment of the present application, the calculation module 200 is specifically used to, based on the circuit superposition principle, split the flexible DC traction power supply system into a load subsystem and a cooperative subsystem, and perform equivalent transformation on the load and traction station in the flexible DC traction power supply system, and decompose the traction station voltage into common-mode voltage and differential-mode voltage, and perform circuit calculation after setting the current source and voltage source in the load subsystem and the cooperative subsystem to decompose the traction station current into the traction station load current and the traction station cooperative current, and decompose the traction station rail potential into the traction station rail potential load component and the traction station rail potential cooperative component.

[0115] Optionally, in one embodiment of the present application, the management module 300 is specifically configured to: when the load current of any traction station in the flexible DC traction power supply system is greater than or equal to a preset traction station current limit value, select at least one traction station from the other traction stations for support according to a first preset condition to transfer the load current of the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the load current of any traction station in the flexible DC traction power supply system is less than the power lighting load current of the traction station, select at least one traction station from the other traction stations for support according to a second preset condition to absorb the regenerative braking current of the locomotive near the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the rail potential at any traction station in the flexible DC traction power supply system exceeds the preset traction station rail potential limit value, select at least one traction station from the other traction stations for support according to a third preset condition to adjust the rail potential distribution, wherein the sum of the coordinated current reference instructions of the traction stations providing support is zero.

[0116] Optionally, in one embodiment of the present application, the management module 300 is specifically used to generate a traction station voltage reference instruction based on the split flexible DC traction power supply system, according to the branch voltage vector in the collaborative subsystem and the branch current vector in the collaborative subsystem, as well as the common mode voltage and the differential mode voltage.

[0117] It should be noted that the above explanation of the embodiment of the energy management method of the flexible DC traction power supply system based on the superposition circuit is also applicable to the energy management device of the flexible DC traction power supply system based on the superposition circuit in this embodiment, and will not be repeated here.

[0118] According to the flexible DC traction power supply system energy management device based on superposition circuit proposed in the embodiment of the present application, the flexible and controllable characteristics of the flexible DC traction power supply system are fully utilized, and system-level collaborative optimization control is achieved by controlling the voltage of each traction station, thereby significantly improving the energy conservation and emission reduction effects and economic benefits of the DC traction power supply system. The device is suitable for newly built urban or intercity rail transit lines that adopt flexible DC traction power supply systems, as well as for partial or full-line technical transformation of existing DC traction power supply systems with insufficient power supply capacity.

[0119] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0120] A memory 801 , a processor 802 , and a computer program stored in the memory 801 and executable on the processor 802 .

[0121] When the processor 802 executes the program, the energy management method for the flexible DC traction power supply system based on the superposition circuit provided in the above embodiment is implemented.

[0122] Furthermore, the electronic device further includes:

[0123] The communication interface 803 is used for communication between the memory 801 and the processor 802 .

[0124] The memory 801 is used to store computer programs that can be run on the processor 802.

[0125] The memory 801 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0126] If the memory 801, processor 802, and communication interface 803 are implemented independently, the communication interface 803, memory 801, and processor 802 can be connected to each other via a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0127] Optionally, in a specific implementation, if the memory 801, the processor 802 and the communication interface 803 are integrated on a chip, the memory 801, the processor 802 and the communication interface 803 can communicate with each other through an internal interface.

[0128] The processor 802 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0129] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, characterized in that when the program is executed by a processor, the above-mentioned flexible DC traction power supply system energy management method based on superposition circuit is implemented.

[0130] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0131] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0132] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0133] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0134] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

Claims

1. A method for energy management of a flexible DC traction power supply system based on a superposition circuit, characterized in that: The following steps are involved: Obtain the traction station port voltage, traction station rail potential, and traction station current of the flexible DC traction power supply system; The traction station load current is obtained by decomposing the traction station current, the traction station rail potential load component is obtained by decomposing the traction station rail potential, and a traction station coordinated current reference value is calculated based on the traction station load current and the traction station rail potential load component, and a traction station voltage reference value is calculated based on the traction station coordinated current reference value, specifically including: Based on the circuit superposition principle, the flexible DC traction power supply system is split into a load subsystem and a collaborative subsystem, and equivalent transformation is performed on the load and traction station in the flexible DC traction power supply system, and the voltage of the traction station is decomposed into common-mode voltage and differential-mode voltage; After setting the current sources and voltage sources in the load subsystem and the coordination subsystem, circuit calculation is performed to decompose the traction station current into the traction station load current and the traction station coordination current, and decompose the traction station rail potential into the traction station rail potential load component and the traction station rail potential coordination component; and According to the traction station coordinated current reference value and the traction station voltage reference value, a traction station voltage reference instruction and a traction station current reference instruction are generated, and the power supply of the flexible DC traction power supply system is controlled according to the traction station voltage reference instruction and the traction station current reference instruction.

2. The method according to claim 1, characterized in that Generating the traction current reference instruction includes: When the load current of any traction station in the flexible DC traction power supply system is greater than or equal to a preset traction station current limit value, at least one traction station from the other traction stations is selected for support according to a first preset condition to transfer the load current of the traction station, wherein the sum of the coordinated current reference command of the traction station and the coordinated current reference command of the traction station providing support is zero; When the load current of any traction station in the flexible DC traction power supply system is less than the power and lighting load current of the traction station, at least one traction station from the other traction stations is selected for support according to a second preset condition to absorb the regenerative braking current of the locomotive near the traction station, wherein the sum of the coordinated current reference command of the traction station and the coordinated current reference command of the traction station providing support is zero; When the rail potential at any traction station in the flexible DC traction power supply system exceeds a preset traction station rail potential limit value, at least one traction station from the other traction stations is selected for support according to a third preset condition to adjust the rail potential distribution, wherein the sum of the coordinated current reference instructions of the traction stations providing support is zero.

3. The method according to claim 1, characterized in that Generating the traction station voltage reference instruction, including: Based on the split flexible DC traction power supply system, the traction substation voltage reference instruction is generated according to the branch voltage vector and the branch current vector in the cooperative subsystem, as well as the common mode voltage and the differential mode voltage.

4. A flexible DC traction power supply system energy management device based on superposition circuit, characterized in that: include: An acquisition module is used to obtain the traction station port voltage, traction station rail potential, and traction station current of the flexible DC traction power supply system; A calculation module is configured to decompose the traction station current to obtain a traction station load current, decompose the traction station rail potential to obtain a traction station rail potential load component, calculate a traction station coordinated current reference value based on the traction station load current and the traction station rail potential load component, and calculate a traction station voltage reference value based on the traction station coordinated current reference value, and is specifically configured to: Based on the principle of circuit superposition, the flexible DC traction power supply system is split into a load subsystem and a cooperative subsystem, and equivalent transformation is performed on the load and traction station in the flexible DC traction power supply system, and the voltage of the traction station is decomposed into a common-mode voltage and a differential-mode voltage. After setting the current source and voltage source in the load subsystem and the cooperative subsystem, circuit calculation is performed to decompose the traction station current into the traction station load current and the traction station cooperative current, and decompose the traction station rail potential into the traction station rail potential load component and the traction station rail potential cooperative component; as well as A management module is used to generate a traction station voltage reference instruction and a traction station current reference instruction based on the traction station coordinated current reference value and the traction station voltage reference value, and control the power supply of the flexible DC traction power supply system according to the traction station voltage reference instruction and the traction station current reference instruction.

5. The device according to claim 4, characterized in that The management module is specifically configured to: when the load current of any traction station in the flexible DC traction power supply system is greater than or equal to a preset traction station current limit value, select at least one traction station from other traction stations for support according to a first preset condition to transfer the load current of the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the load current of any traction station in the flexible DC traction power supply system is less than the power and lighting load current of the traction station, select at least one traction station from other traction stations for support according to a second preset condition to absorb the regenerative braking current of the locomotive near the traction station, wherein the sum of the coordinated current reference instruction of the traction station and the coordinated current reference instruction of the traction station providing support is zero; when the rail potential at any traction station in the flexible DC traction power supply system exceeds the preset traction station rail potential limit value, select at least one traction station from other traction stations for support according to a third preset condition to adjust the rail potential distribution, wherein the sum of the coordinated current reference instructions of the traction stations providing support is zero.

6. The device according to claim 4, characterized in that The management module is specifically used to generate the traction substation voltage reference instruction based on the split flexible DC traction power supply system, the branch voltage vector in the collaborative subsystem, the branch current vector in the collaborative subsystem, and the common-mode voltage and the differential-mode voltage.

7. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the energy management method for a flexible DC traction power supply system based on a superposition circuit as described in any one of claims 1 to 3.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the energy management method of a flexible DC traction power supply system based on a superposition circuit as described in any one of claims 1 to 3.

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