A network voltage adaptive control method and device and power supply system

Abstract

The present application belongs to the field of power electronics and rail transit power supply technology, and particularly relates to a network voltage adaptive control method, device and power supply system. The network voltage adaptive control method comprises: adopting scheme one and / or scheme two to realize network voltage adaptive control; scheme one: when U dc2 <U dc1 +ΔU c_set2 , and U c_min ≤U c ≤U c_max , control jumps to a discharging mode to make the super capacitor discharge to the DC overhead line; scheme two: when U dc2 >U dc1 +ΔU c_set1 , and U c_min ≤U c ≤U c_max , control jumps to a charging mode to make the DC overhead line charge the super capacitor. The network voltage adaptive control method combines AC power grid voltage and DC overhead line voltage to realize adaptive control of super capacitor charging and discharging, and avoids the situation of super capacitor misoperation caused by AC power grid fluctuation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power electronics and rail transit power supply, and particularly relates to a network voltage adaptive control method, device and power supply system. BACKGROUND

[0002] At present, the absorption modes of regenerative energy of rail transit include resistance absorption type, inverter feedback type, super capacitor energy storage type and the like. The super capacitor energy storage type stores the excess energy generated during braking of a rail vehicle into a super capacitor in the form of capacitor energy storage, and releases the energy from the super capacitor during traction of the rail vehicle. This type has the advantages of low carbon, energy saving, green environmental protection, stability and reliability, and is one of the development directions of regenerative braking energy absorption of urban rail transit in the future.

[0003] The working mode of the super capacitor energy storage device is usually as follows: the voltage of the DC catenary is detected, and then compared with a charging start threshold or a discharging start threshold. When the voltage of the DC catenary is higher than the charging start threshold, the device charges and absorbs the DC network energy to store in the super capacitor. When the voltage of the DC catenary is lower than the discharging start threshold, the device releases the energy in the super capacitor to the DC catenary.

[0004] However, the above working mode often has the following problems: since the DC catenary voltage is a DC voltage obtained by rectification of a rectifier, when the AC network voltage fluctuates, the DC catenary voltage also fluctuates. Relying only on the DC network voltage for judgment can easily lead to false charging and energy absorption or false discharging and energy release of the super capacitor energy storage device. SUMMARY

[0005] The present application aims to provide a network voltage adaptive control method, device and power supply system to solve the problem of false operation of the super capacitor caused by the prior art only judging according to the DC catenary voltage.

[0006] To achieve the above purpose, the technical solution adopted by the present application includes:

[0007] The network voltage adaptive control method of the present application adopts scheme one and / or scheme two to realize network voltage adaptive control.

[0008] Scheme one: when U dc2 U dc1 + ΔU c_set2 , and U c_min ≤ U c ≤ U c_max , control jumps to the discharging mode to make the super capacitor discharge to the DC catenary.

[0009] Scheme two: when U dc2 > U dc1 + ΔUc_set1 , and U c_min ≤ U c ≤ U c_max When the condition is met, the control jumps to the charging mode, and the DC catenary charges the super capacitor;

[0010] Wherein, U dc1 is the DC terminal voltage of the AC / DC rectifier, U dc2 is the DC catenary voltage, ΔU c_set1 is the super capacitor charging voltage threshold, ΔU c_set2 is the super capacitor discharging voltage threshold, U c is the super capacitor voltage, U c_max is the maximum working voltage of the super capacitor, U c_min is the minimum working voltage of the super capacitor; ΔU c_set1 is greater than 0, and ΔU c_set2 is less than 0; the AC terminal of the AC / DC rectifier is used for connecting the AC power grid, the DC terminal of the AC / DC rectifier is connected with the DC catenary, and the DC catenary is further connected with the super capacitor.

[0011] The beneficial effects are that: the network voltage self-adaptive control method takes the rectifier DC terminal voltage as the reference, combines with the DC catenary voltage, and when the rectifier DC terminal voltage fluctuates due to the fluctuation of the AC power grid, the power supply system will not change the working state due to slight voltage fluctuation because of the existence of the super capacitor charging and discharging threshold, so as to realize the self-adaptive control of the power supply system; when scheme one is adopted, the problem of super capacitor mis-discharging can be solved; when scheme two is adopted, the problem of super capacitor mis-charging can be solved; when scheme one and scheme two are adopted, the problems of super capacitor mis-charging and mis-discharging can be solved.

[0012] Further, in scheme one, when U c <U c_min , or I dc is 0, or U dc2 > U dc1 - ΔU2, the control makes the super capacitor turn to the standby mode; in scheme two, U c > U c_max , or I dc is 0, or U dc2 <U dc1 + ΔU2, the control makes the super capacitor turn to the standby mode; wherein, the DC / DC converter is arranged between the DC catenary and the super capacitor, I dc is the current between the DC catenary and the DC / DC converter, and ΔU2 is the standby voltage threshold of the super capacitor.

[0013] Its beneficial effects are: combining the DC terminal voltage of the rectifier, the DC contact network voltage, and the supercapacitor voltage to determine the standby state of the supercapacitor, avoiding the situation in the prior art where the standby state of the supercapacitor is incorrectly determined by relying solely on the DC contact network voltage, and further improving the reliability of the power supply system.

[0014] Furthermore, in Scheme 1, the discharge current when the supercapacitor discharges to the DC contact network is 0.4I. n -0.6I n The constant current between; I n This refers to the current between the DC / DC converter and the supercapacitor.

[0015] Its beneficial effect is that it controls the discharge current to 0.4I. n -0.6I n A constant current is maintained between them to ensure that the supercapacitor can release the energy of the DC contact network in a timely manner.

[0016] Furthermore, in Scheme 2, when the DC contact network charges the supercapacitor, the charging current is 0.2I. n -0.35I n The constant current between; I n This refers to the current between the DC / DC converter and the supercapacitor.

[0017] Its beneficial effects are: following the principle of "slow charging", it protects the supercapacitor while ensuring that the supercapacitor can absorb the energy of the DC contact network in a timely manner.

[0018] Furthermore, the DC terminal voltage U of the rectifier dc1 It is calculated from the AC terminal voltage of the rectifier.

[0019] The present invention provides a grid voltage adaptive control device, comprising: a processor and a memory; the processor is used to execute program instructions stored in the memory to implement the above-described grid voltage adaptive control method and achieve the same beneficial effects as the above-described method.

[0020] The present invention provides a power supply system comprising: an AC power grid, an AC / DC rectifier, a DC contact network, and a supercapacitor. The AC power grid is connected to the DC contact network via the AC / DC rectifier, and the DC contact network is also connected to the supercapacitor. The system also includes a data acquisition module and a grid voltage adaptive control device. The data acquisition module is used to acquire the DC terminal voltage U of the AC / DC rectifier. dc1 DC contact network voltage U dc2 and supercapacitor voltage U c The adaptive grid voltage control device includes a processor and a memory. The processor executes program instructions stored in the memory to implement the following method: Adaptive grid voltage control is achieved using Scheme 1 and / or Scheme 2.

[0021] Scheme one: when U dc2 <U dc1 + ΔU c_set2 , and U c_min ≤ U c ≤ U c_max , control jumps to the discharging mode, and the super capacitor is discharged to the DC catenary;

[0022] Scheme two: when U dc2 > U dc1 + ΔU c_set1 , and U c_min ≤ U c ≤ U c_max , control jumps to the charging mode, and the DC catenary charges the super capacitor;

[0023] Wherein, U dc1 is the DC end voltage of the AC / DC rectifier, U dc2 is the DC catenary voltage, ΔU c_set1 is the super capacitor charging voltage threshold, ΔU c_set2 is the super capacitor discharging voltage threshold, U c is the super capacitor voltage, U c_max is the maximum working voltage of the super capacitor, U c_min is the minimum working voltage of the super capacitor; ΔU c_set1 is greater than 0, and ΔU c_set2 is less than 0.

[0024] The power supply system has the beneficial effects that: the power supply system provided by the application judges the working state of the power supply system by combining the DC end voltage U dc1 of the AC / DC rectifier and the DC catenary voltage U dc2 and introducing the threshold value, avoids the situation that the power supply system is mischarged or misdischarged due to the fact that only the DC catenary voltage is used for judgment in the prior art, and improves the reliability of the power supply system.

[0025] Further, the DC / DC converter is arranged between the DC catenary and the super capacitor; the acquisition module is further used to acquire the current I dc between the DC catenary and the DC / DC converter; and the processor is further used to realize the following method: in scheme one, when U c <U c_min , or I dc is 0, or U dc2 > U dc1 - ΔU2, the super capacitor is controlled to be switched to the standby mode; in scheme two, U c > U c_max , or I dc is 0, or U dc2dc1 When +ΔU2 is reached, the supercapacitor is switched to standby mode; where ΔU2 is the standby voltage threshold of the supercapacitor.

[0026] Its beneficial effects are: by combining the DC terminal voltage of the rectifier, the DC contact network voltage, and the supercapacitor voltage, the standby state of the supercapacitor can be determined, avoiding the situation in the prior art where the standby state of the power supply system is incorrectly determined by relying solely on the DC contact network voltage, thus further improving the reliability of the power supply system.

[0027] Furthermore, the acquisition module is also used to acquire the current I between the DC / DC converter and the supercapacitor. n In Scheme 1, the discharge current is 0.4I when the supercapacitor discharges to the DC contact network. n -0.6I n A constant current between them.

[0028] Its beneficial effect is that it controls the discharge current to 0.4I. n -0.6I n A constant current is maintained between them to ensure that the supercapacitor can release the energy of the DC contact network in a timely manner.

[0029] Furthermore, the acquisition module is also used to acquire the current I between the DC / DC converter and the supercapacitor. n In Scheme Two, when the DC contact network charges the supercapacitor, the charging current is 0.2I. n -0.35I n A constant current between them.

[0030] Its beneficial effects are: following the principle of "slow charging", it protects the supercapacitor while ensuring that the supercapacitor can absorb the energy of the DC contact network in a timely manner.

[0031] Furthermore, the DC terminal voltage U of the rectifier dc1 It is calculated from the AC terminal voltage of the rectifier. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the power supply system in a system embodiment of the present invention;

[0033] Figure 2 This is a flowchart of the adaptive grid voltage control method according to an embodiment of the present invention;

[0034] Figure 3 This is a structural diagram of the adaptive grid voltage control device according to an embodiment of the present invention. Detailed Implementation

[0035] ​In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application, that is, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0036] System embodiments:

[0037] The structural schematic diagram of the power supply system of the present embodiment is shown in Figure 1 , comprising: a 35kV AC power grid, a rectifier voltage reducer, an AC / DC rectifier, a first switch cabinet, a DC contact network, a second switch cabinet, a DC / DC converter, a super capacitor array, an acquisition module (not shown in the figure) and a network voltage adaptive control device (not shown in the figure); wherein the 35kV AC power grid is connected with the rectifier voltage reducer and the AC / DC rectifier in sequence; the DC contact network is connected with the first switch cabinet and the second switch cabinet at both ends, the other end of the first switch cabinet is connected with the DC end of the AC / DC rectifier, and the other end of the second switch cabinet is connected with the high voltage end of the DC / DC converter; the low voltage end of the DC / DC converter is connected with the super capacitor array. The Boost control mode is adopted between the high voltage end of the DC / DC converter and the DC contact network, the Buck control mode is adopted between the low voltage end of the DC / DC converter and the super capacitor, and the main power device of the DC / DC converter is an insulated gate bipolar transistor (IGBT). The acquisition module is used to acquire the AC / DC rectifier AC end voltage U g , the DC contact network voltage U dc2 , the current I dc between the DC contact network and the DC / DC converter, the current I n between the DC / DC converter and the super capacitor, and the super capacitor array voltage U c . The network voltage adaptive control device comprises a processor and a memory, and the processor is used to execute the program instructions stored in the memory to realize a network voltage adaptive control method of the present application, the flow chart of the method is shown in Figure 2 , and the specific steps are as follows:

[0038] When U dc2 <U dc1 +ΔU c_set2 , and U c_min ≤U c ≤U c_max , jump to the discharge mode, and the super capacitor is discharged at 0.5In A constant current is discharged to the DC contact network;

[0039] When discharged to the voltage U of the supercapacitor c Less than the minimum operating voltage U of the supercapacitor c_min , or I dc =0, or U dc2 >U dc1 -ΔU2, then the supercapacitor switches to standby mode;

[0040] When U dc2 >U dc1 +ΔU c_set1 , and U c_min ≤U c ≤U c_max At this time, it switches to charging mode, and the DC contact network operates at 0.3I. n A constant current charges the supercapacitor;

[0041] When charged to the voltage U of the supercapacitor c Greater than the maximum operating voltage U of the supercapacitor c_max , or I dc =0, or U dc2 dc1 +ΔU2, then the supercapacitor switches to standby mode.

[0042] Among them, U dc1 =U g ×1.414, ΔU2 is the standby voltage threshold of the supercapacitor. ΔU c_set1 Set to any value between 60 and 80V, ΔU c_set2 Set to any value between -260 and -230V, and set ΔU2 to any value between 80 and 120V. In this embodiment, the supercapacitor charging voltage threshold ΔU is preset. c_set1 70V, supercapacitor discharge voltage threshold ΔU c_set2 The voltage is -250V, and the standby voltage threshold ΔU2 of the supercapacitor is 100V. Let ΔU1 = U dc1 -U dc2 In standby mode, ΔU1 is 0. If ΔU1 is not 0, U is corrected by zero drift. dc2 This makes ΔU1 equal to 0.

[0043] Method Implementation Examples:

[0044] This method embodiment is aimed at... Figure 1 ​The power supply system shown is illustrated in detail in the system embodiments, including the various components, their connections, and operating principles. The basic concept of the adaptive grid voltage control method employed in this system is to control the operating state of the supercapacitor by utilizing the difference between the rectifier's DC terminal voltage, the DC contact network voltage, and the supercapacitor's voltage, thereby achieving adaptive control. The specific implementation process of this method has been detailed in the system embodiments and will not be repeated here.

[0045] Device Example:

[0046] An embodiment of the adaptive grid voltage control device of the present invention, such as... Figure 3 As shown, the system includes a memory, a processor, and an internal bus. The processor and memory communicate and exchange data with each other via the internal bus. The memory includes at least one software function module stored in the memory. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory, thereby implementing the adaptive grid voltage control method described in the embodiments of the present invention.

[0047] The processor can be a microprocessor (MCU), a programmable logic device (FPGA), or other processing devices. The memory can be any type of memory that stores information using electrical energy, such as RAM and ROM; it can also be any type of memory that stores information using magnetic energy, such as hard disks, floppy disks, magnetic tapes, magnetic core memory, bubble memory, and USB flash drives; it can also be any type of memory that stores information using optical methods, such as CDs and DVDs; and of course, it can also be other types of memory, such as quantum memory and graphene memory.

[0048] Specific implementation methods have been given above, but the present invention is not limited to the described implementation methods. The basic idea of ​​the present invention lies in the above basic scheme. For those skilled in the art, designing various modified models, formulas, and parameters based on the teachings of the present invention does not require creative effort. Changes, modifications, substitutions, and variations made to the implementation methods without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for web pressure adaptive control, the method comprising: determining a target web pressure; determining a current web pressure; determining a difference between the target web pressure and the current web pressure; determining a target web tension based on the difference; determining a current web tension; determining a difference between the target web tension and the current web tension; determining a target web speed based on the difference; determining a current web speed; determining a difference between the target web speed and the current web speed; and adjusting a web pressure control signal based on the difference. When U dc2 <U dc1 + ΔU c_set2 and U c_min ≤ U c ≤ U c_max , the control jumps to the discharge mode, discharging the supercapacitor to the DC catenary; during discharge, the current is a constant current between 0.4I n - 0.6I n . When U dc2 > U dc1 + ΔU c_set1 and U c_min ≤ U c ≤ U c_max , the control jumps to the charging mode, which charges the supercapacitor from the DC catenary; the current during charging is a constant current between 0.2I n - 0.35I n . Wherein, U dc1 is the DC voltage of the AC / DC rectifier collected, U dc2 is the DC contact network voltage, ΔU c_set1 is the super capacitor charging voltage threshold, ΔU c_set2 is the super capacitor discharging voltage threshold, U c is the super capacitor voltage, U c_max is the maximum working voltage of the super capacitor, U c_min is the minimum working voltage of the super capacitor; ΔU c_set1 is in the range of 60-80 volts, ΔU c_set2 is in the range of -260 to -230 volts; the AC end of the AC / DC rectifier is used to connect the AC power grid, the DC end of the AC / DC rectifier is connected to the DC contact network, and the DC contact network is also connected to the super capacitor; I n is the current between the DC / DC converter and the super capacitor.

2. The web pressure adaptive control method of claim 1, wherein: When U c <U c_min , or I dc is 0, or U dc2 > U dc1 - ΔU2, the control super capacitor is switched to standby mode; U c > U c_max , or I dc is 0, or U dc2 <U dc1 + ΔU2, the control super capacitor is switched to standby mode; wherein a DC / DC converter is arranged between the DC catenary and the super capacitor, I dc is the current between the DC catenary and the DC / DC converter, and ΔU2 is the super capacitor standby voltage threshold.

3. The web pressure adaptive control method of claim 2, wherein: When the super capacitor is in standby mode, if AU1≠0, then through zero drift correction, AU1=0, AU1=U dc1 - U dc2 .

4. The web pressure adaptive control method of claim 1, wherein: The rectifier DC terminal voltage U dc1 Is calculated by the rectifier AC terminal voltage.

5. A web pressure adaptive control apparatus characterized by:

2. The method of claim 1, wherein the target web pressure 6. A power supply system comprising an AC network, an AC / DC rectifier, a DC catenary and a supercapacitor, the AC network being connected to the DC catenary via the AC / DC rectifier, the DC catenary further being connected to the supercapacitor, characterized in that: Also included are a collection module and a network voltage adaptive control device; the collection module is used to collect AC / DC rectifier direct current end voltage U dc1 , direct current catenary voltage U dc2 , and super capacitor voltage U c ; the network voltage adaptive control device includes a processor and a memory, and the processor is used to execute program instructions stored in the memory to realize the following method: When U dc2 <U dc1 + ΔU c_set2 and U c_min ≤ U c ≤ U c_max , the control jumps to the discharge mode, discharging the supercapacitor to the DC catenary; during discharge, the current is a constant current between 0.4I n - 0.6I n . When U dc2 > U dc1 + ΔU c_set1 and U c_min ≤ U c ≤ U c_max , the control jumps to the charging mode, which charges the supercapacitor from the DC catenary; the current during charging is a constant current between 0.2I n - 0.35I n . Wherein, U dc1 is the DC voltage of the collected AC / DC rectifier, U dc2 is the DC catenary voltage, ΔU c_set1 is the super capacitor charging voltage threshold, ΔU c_set2 is the super capacitor discharging voltage threshold, U c is the super capacitor voltage, U c_max is the maximum working voltage of the super capacitor, U c_min is the minimum working voltage of the super capacitor; ΔU c_set1 is the value range of 60-80 volts, ΔU c_set2 is the value range of -260 to -230 volts; I n is the current between the DC / DC converter and the super capacitor.

7. The power supply system of claim 6, wherein: A DC / DC converter is installed between the DC contact network and the supercapacitor; the acquisition module is also used to acquire the current I between the DC contact network and the DC / DC converter. dc The processor is also used to implement the following methods: when U c c_min 、 or I dc 0, or U dc2 >U dc1 When -∆U2 is reached, the supercapacitor is switched to standby mode; U c >U c_max 、 or I dc 0, or U dc2 dc1 When +∆U2 is reached, the supercapacitor is switched to standby mode; where ∆U2 is the standby voltage threshold of the supercapacitor.​​ 8. The power supply system of claim 7, wherein: When the super capacitor is in standby mode, if AU1≠0, then through zero drift correction, AU1=0, AU1=U dc1 - U dc2 .

9. The power supply system of claim 6, wherein: The rectifier DC terminal voltage U dc1 Calculated by the rectifier AC terminal voltage.

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