CN112356741B - Feedback control method and system based on PWM energy feedback converter - Google Patents

Abstract

The invention discloses a feedback control method and system based on a PWM energy feedback converter. The method comprises the steps that a direct current side of the PWM energy feedback converter is connected into a direct current contact network, and an alternating current side is connected into an alternating current power grid through a transformer; detecting two direct current contact network voltages in a time sliding window; calculating a voltage change value delta U of the direct-current contact net; comparing the voltage change value delta U of the direct-current contact net with a preset condition of a control system, and judging the working condition of the system; and if the direct current voltage value meets the preset system working condition and reaches the set threshold value, the PWM energy feedback converter carries out real-time adjustment according to the judgment result. The system comprises an energy-feedback converter access device, a voltage detection device, a voltage change calculation device, a working condition judgment device and an adjustment device. The method judges the running state of the train through the change of the voltage of the direct current contact network, solves the problems of stability and reliability in the engineering application of the PWM converter, controls the accurate input of the PWM rectifier, achieves the aim of saving energy of a power supply system, and has simple and accurate criterion.

Description

A feedback control method and system based on PWM energy-feedback converter

technical field

The invention relates to the technical field of urban rail transit power supply, in particular to a feedback control method and system based on a PWM energy-feedback converter.

Background technique

In the existing urban rail transit power supply system, diode rectifiers are generally used as the power supply for trains. Diode rectifiers have the advantages of high efficiency, large capacity, strong overload capacity, etc., but also have disadvantages such as uncontrollable output voltage, large ripple, and unidirectional energy flow that cannot be used for regenerative braking energy absorption and utilization. When the train starts running, the diode rectifier rectifies the work to provide traction energy to the train. When the train brakes, it is in the braking power generation mode, the DC bus voltage rises, the catenary voltage fluctuates within a certain range with the change of the train load on the catenary, and the PWM changes. The current transformer feeds back the power of the train braking to the AC grid by detecting the change of the DC bus voltage and the change slope. However, the PWM converter is prone to misjudgment, and forms a power circulation with the diode rectifier unit, which makes it difficult to accurately judge the running state of the train, which is not conducive to the energy utilization of the rail power supply system.

SUMMARY OF THE INVENTION

In view of this, the purpose of the embodiments of the present invention is to provide a feedback control method and system based on a PWM energy-feedback converter, which can accurately determine the running state of the train through the change of the DC catenary voltage and avoid the PWM converter. The misjudgment and the diode rectifier unit form a power circulation, which solves the problems of stability and reliability in the engineering application of the PWM converter, so as to control the accurate input of the PWM rectifier and achieve the purpose of energy saving in the power supply system. The criterion is simple and accurate.

In a first aspect, an embodiment of the present invention provides a feedback control method based on a PWM energy-feedback converter, including:

The DC side of the PWM energy-feeding converter is connected to the DC catenary, and the AC side is connected to the AC grid through the transformer.

Detection of two DC catenary voltages within a time sliding window.

Calculate the DC catenary voltage change value △U.

Compare the DC catenary voltage change value △U with the preset conditions of the control system to judge the system operating conditions.

If the preset system operating conditions are met, and the DC voltage value reaches the set threshold at the same time, the PWM energy-feeding converter will adjust in real time according to the judgment result.

With reference to the first aspect, the embodiment of the present invention provides the first possible implementation manner of the first aspect, wherein the comparing the DC catenary voltage change value ΔU and the preset conditions of the control system to determine the system operating conditions, including :

If the voltage change value △U≤δ1, it is judged that the voltage fluctuation of the power supply network or the voltage fluctuation caused by the rectification of the diode rectifier causes the voltage fluctuation of the catenary.

If the voltage change value △U<0, and the absolute value of the voltage change value δ1<|△U|≤δ2, it is judged that the catenary voltage fluctuation is caused by the start of the train traction.

If the voltage change value △U>0, and the absolute value of the voltage change value δ2<|△U|≤δ3, it is judged that the train braking causes the voltage fluctuation of the traction network.

In conjunction with the first aspect, the embodiment of the present invention provides the second possible implementation manner of the first aspect, wherein, if the preset system operating conditions are met, and the DC voltage value reaches the set threshold value, the PWM energy feed changes The streamer makes real-time adjustments based on the judgment results, including:

If the voltage change value △U>0, the absolute value of the voltage change value δ2＜|△U| The energy is fed back to the AC grid.

If the voltage change value △U>0, the absolute value of the voltage change value δ2＜|△U| The energy of the DC catenary is fed back to the AC grid.

If the voltage change value is 0<△U≤δ1, the threshold value of the startup voltage is increased in the positive direction, and the PWM energy-feeding converter maintains the standby state.

If the voltage change value △U≤0, the threshold value of the startup voltage is reduced in the reverse direction, and the PWM energy-feeding converter maintains the standby state.

In a second aspect, an embodiment of the present invention also provides a feedback control system based on a PWM energy-feedback converter, including:

The energy-feeding converter is connected to the device, the DC side of the PWM energy-feeding converter is connected to the DC catenary, and the AC side is connected to the AC grid through the transformer.

The voltage detection device detects the voltage of the two DC catenary within the time sliding window.

The voltage change calculation device calculates the voltage change value △U of the DC catenary.

The working condition judgment device compares the DC catenary voltage change value △U with the preset conditions of the control system, and judges the system working condition.

In the adjustment device, if the preset system operating conditions are met, and the DC voltage value reaches the set threshold at the same time, the PWM energy-feeding converter performs real-time adjustment according to the judgment result.

In conjunction with the second aspect, the embodiment of the present invention provides a first possible implementation manner of the second aspect, wherein the working condition judgment device includes:

The system voltage fluctuation judgment module is used to judge that the voltage fluctuation of the power supply network or the voltage fluctuation caused by the rectification of the diode rectifier causes the voltage fluctuation of the catenary if the voltage change value △U≤δ1.

The train traction start judgment module is used to judge that the catenary voltage fluctuation is caused by the train traction start if the voltage change value △U<0, and the absolute value of the voltage change value δ1<|△U|≤δ2.

The train braking judgment module is used to judge that the voltage fluctuation of the traction network is caused by the train braking if the voltage change value △U>0 and the absolute value of the voltage change value δ2<|△U|≤δ3.

In conjunction with the second aspect, the embodiment of the present invention provides a second possible implementation manner of the second aspect, wherein the adjustment device includes:

The no-load voltage comparison module is used to start the PWM energy feeder if the voltage change value △U>0, the absolute value of the voltage change value δ2<|△U|≤δ3, and the DC voltage value is greater than the no-load voltage value of the DC catenary The energy of the DC catenary is fed back to the AC grid.

The converter voltage comparison module is used to start if the voltage change value △U>0, the absolute value of the voltage change value δ2<|△U|≤δ3, and the DC voltage value is greater than the preset voltage threshold of the PWM energy-feeding converter The PWM energy-feeding converter feeds back the energy of the DC catenary to the AC grid.

The voltage change value comparison module is used to increase the threshold of the startup voltage in the forward direction if the voltage change value is 0<△U≤δ1, and the PWM energy-feeding converter maintains the standby state. If the voltage change value △U≤0, the reverse direction decreases. The threshold value of the small start-up voltage, the PWM can feed the converter to maintain the standby state.

The beneficial effects of the embodiments of the present invention are:

The invention accurately judges the running state of the train through the change of the DC catenary voltage, avoids the misjudgment of the PWM converter and the power circulation of the diode rectifier set, and solves the problems of stability and reliability in the engineering application of the PWM converter , so as to control the accurate input of the PWM rectifier to achieve the purpose of energy saving in the power supply system, and the criterion is simple and accurate.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

The feedback control method and system based on a PWM energy-feedback converter of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

1 is a flowchart of a feedback control method based on a PWM energy-feedback converter of the present invention;

FIG. 2 is a schematic diagram of the access structure of the PWM energy-feeding converter of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein can be arranged and designed in a variety of different configurations.

Some embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below and features in the embodiments may be combined with each other without conflict.

Referring to FIGS. 1 to 2 , a first embodiment of the present invention provides a feedback control method based on a PWM energy-fed converter, including:

The DC side of the PWM energy-feeding converter is connected to the DC catenary, and the AC side is connected to the AC grid through the transformer.

Detection of two DC catenary voltages within a time sliding window.

Calculate the DC catenary voltage change value △U.

Compare the DC catenary voltage change value △U with the preset conditions of the control system to judge the system operating conditions.

If the preset system operating conditions are met, and the DC voltage value reaches the set threshold at the same time, the PWM energy-feeding converter will adjust in real time according to the judgment result.

Wherein, the comparison between the DC catenary voltage change value ΔU and the preset conditions of the control system to judge the system operating conditions includes:

If the voltage change value △U≤δ1, it is judged that the voltage fluctuation of the power supply network or the voltage fluctuation caused by the rectification of the diode rectifier causes the voltage fluctuation of the catenary.

If the voltage change value △U<0, and the absolute value of the voltage change value δ1<|△U|≤δ2, it is judged that the catenary voltage fluctuation is caused by the start of the train traction.

If the voltage change value △U>0, and the absolute value of the voltage change value δ2<|△U|≤δ3, it is judged that the train braking causes the voltage fluctuation of the traction network.

Wherein, if the preset system operating conditions are met, and the DC voltage value reaches the set threshold at the same time, the PWM energy-feeding converter performs real-time adjustment according to the judgment result, including:

If the voltage change value △U>0, the absolute value of the voltage change value δ2＜|△U| The energy is fed back to the AC grid.

If the voltage change value △U>0, the absolute value of the voltage change value δ2＜|△U| The energy of the DC catenary is fed back to the AC grid.

If the voltage change value is 0<△U≤δ1, the threshold value of the startup voltage is increased in the positive direction, and the PWM energy-feeding converter maintains the standby state.

If the voltage change value △U≤0, the threshold value of the startup voltage is reduced in the reverse direction, and the PWM energy-feeding converter maintains the standby state.

Referring to FIGS. 1 to 2 , a second embodiment of the present invention provides a feedback control system based on a PWM energy-feedback converter, including:

The energy-feeding converter is connected to the device, the DC side of the PWM energy-feeding converter is connected to the DC catenary, and the AC side is connected to the AC grid through the transformer.

The voltage detection device detects the voltage of the two DC catenary within the time sliding window.

The voltage change calculation device calculates the voltage change value △U of the DC catenary.

The working condition judgment device compares the DC catenary voltage change value △U with the preset conditions of the control system, and judges the system working condition.

In the adjustment device, if the preset system operating conditions are met, and the DC voltage value reaches the set threshold at the same time, the PWM energy-feeding converter performs real-time adjustment according to the judgment result.

Wherein, the working condition judgment device includes:

The system voltage fluctuation judgment module is used to judge that the voltage fluctuation of the power supply network or the voltage fluctuation caused by the rectification of the diode rectifier causes the voltage fluctuation of the catenary if the voltage change value △U≤δ1.

The train traction start judgment module is used to judge that the catenary voltage fluctuation is caused by the train traction start if the voltage change value △U<0, and the absolute value of the voltage change value δ1<|△U|≤δ2.

The train braking judgment module is used to judge that the voltage fluctuation of the traction network is caused by the train braking if the voltage change value △U>0 and the absolute value of the voltage change value δ2<|△U|≤δ3.

Wherein, the adjustment device includes:

The no-load voltage comparison module is used to start the PWM energy feeder if the voltage change value △U>0, the absolute value of the voltage change value δ2<|△U|≤δ3, and the DC voltage value is greater than the no-load voltage value of the DC catenary The energy of the DC catenary is fed back to the AC grid.

The converter voltage comparison module is used to start if the voltage change value △U>0, the absolute value of the voltage change value δ2<|△U|≤δ3, and the DC voltage value is greater than the preset voltage threshold of the PWM energy-feeding converter The PWM energy-feeding converter feeds back the energy of the DC catenary to the AC grid.

The voltage change value comparison module is used to increase the threshold of the startup voltage in the forward direction if the voltage change value is 0<△U≤δ1, and the PWM energy-feeding converter maintains the standby state. If the voltage change value △U≤0, the reverse direction decreases. The threshold value of the small start-up voltage, the PWM can feed the converter to maintain the standby state.

The embodiment of the present invention aims to protect a feedback control method and system based on a PWM energy-feedback converter, and has the following effects:

The invention accurately judges the running state of the train through the change of the DC catenary voltage, avoids the misjudgment of the PWM converter and the power circulation of the diode rectifier set, and solves the problems of stability and reliability in the engineering application of the PWM converter , so as to control the accurate input of the PWM rectifier to achieve the purpose of energy saving in the power supply system, and the criterion is simple and accurate.

The computer program product of the feedback control method and device based on the PWM energy-fed converter provided by the embodiments of the present invention includes a computer-readable storage medium storing program codes, and the instructions included in the program codes can be used to execute the foregoing method embodiments. The specific implementation can refer to the method embodiment, which is not repeated here.

Specifically, the storage medium can be a general storage medium, such as a removable disk, a hard disk, etc., when the computer program on the storage medium is run, the above-mentioned feedback control method based on a PWM energy-feedback converter can be executed, so as to control the PWM The rectifier is put in accurately to achieve the purpose of energy saving in the power supply system.

The functions, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a processor-executable non-volatile computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be embodied in the form of a software product in essence, or the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes.

Finally, it should be noted that the above-mentioned embodiments are only specific implementations of the present invention, and are used to illustrate the technical solutions of the present invention, but not to limit them. The protection scope of the present invention is not limited thereto, although referring to the foregoing The embodiment has been described in detail the present invention, those of ordinary skill in the art should understand: any person skilled in the art who is familiar with the technical field within the technical scope disclosed by the present invention can still modify the technical solutions described in the foregoing embodiments. Or can easily think of changes, or equivalently replace some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be covered in the present invention. within the scope of protection. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (4)

1. A feedback control method based on a PWM energy feedback converter is characterized by comprising the following steps:

the direct current side of the PWM energy feedback converter is connected into a direct current contact network, and the alternating current side is connected into an alternating current power grid through a transformer;

detecting two direct current contact network voltages in a time sliding window;

calculating a voltage change value delta U of the direct-current contact network;

comparing the voltage change value delta U of the direct-current contact net with a preset condition of a control system, and judging the working condition of the system;

if the direct current voltage value meets the preset system working condition and reaches the set threshold value, the PWM energy feedback converter carries out real-time adjustment according to the judgment result;

comparing the voltage change value delta U of the direct-current contact net with the preset condition of the control system, and judging the working condition of the system, wherein the method comprises the following steps:

if the voltage change value delta U is less than or equal to delta 1, judging that the voltage fluctuation of a power supply network or the voltage fluctuation caused by the rectification of a diode rectifier causes the voltage fluctuation of a contact network;

if the voltage change value delta U is less than 0 and the absolute value delta 1 of the voltage change value is less than or equal to delta U and less than or equal to delta 2, judging that the voltage fluctuation of the contact network is caused by the traction start of the train;

if the voltage change value delta U is larger than 0 and the absolute value delta 2 of the voltage change value is smaller than the absolute value delta U and smaller than or equal to delta 3, the voltage fluctuation of the traction network caused by train braking is judged.

2. The feedback control method of claim 1, wherein if the feedback control method meets a preset system condition and the dc voltage value reaches a set threshold, the PWM converter performs real-time adjustment according to the determination result, and the method comprises:

if the voltage change value delta U is more than 0, the absolute value delta U of the voltage change value delta 2 is less than and equal to delta 3, and the direct-current voltage value is greater than the no-load voltage value of the direct-current contact network, starting the PWM energy feedback converter, and feeding the energy of the direct-current contact network back to the alternating-current power grid;

if the voltage change value delta U is more than 0, the absolute value delta U of the voltage change value delta 2 is more than and less than or equal to delta 3, and the direct current voltage value is greater than the preset voltage threshold value of the PWM energy feedback converter, the PWM energy feedback converter is started, and the energy of the direct current contact net is fed back to the alternating current power grid;

if the voltage change value is more than 0 and less than or equal to delta U and less than or equal to delta 1, the threshold value of the starting voltage is increased in the positive direction, and the PWM energy can be fed to the converter to maintain a standby state;

if the voltage change value delta U is less than or equal to 0, the threshold value of the starting voltage is reversely reduced, and the PWM energy-fed converter maintains the standby state.

3. A feedback control system based on a PWM energy feedback converter is characterized by comprising:

the energy feedback converter access device is characterized in that a direct current side of the PWM energy feedback converter is accessed to a direct current contact network, and an alternating current side is accessed to an alternating current power grid through a transformer;

the voltage detection device is used for detecting the voltages of the two direct current contact networks in the time sliding window;

the voltage change calculating device is used for calculating a voltage change value delta U of the direct-current contact network;

the working condition judgment device is used for comparing the voltage change value delta U of the direct-current contact network with a preset condition of the control system and judging the working condition of the system;

if the direct current voltage value meets the preset system working condition and reaches the set threshold value, the PWM energy feedback converter carries out real-time adjustment according to the judgment result;

the working condition judging device comprises:

the system voltage fluctuation judging module is used for judging that the voltage fluctuation of a power supply network or the voltage fluctuation of a contact network is caused by the rectification of a diode rectifier if the voltage change value delta U is less than or equal to delta 1;

the train traction starting judgment module is used for judging that the voltage fluctuation of a contact net is caused by train traction starting if the voltage change value delta U is less than 0 and the absolute value delta 1 of the voltage change value is less than or equal to delta U and less than or equal to delta 2;

and the train braking judgment module is used for judging that the train braking causes the voltage fluctuation of the traction network if the voltage change value delta U is more than 0 and the absolute value delta 2 of the voltage change value is less than or equal to delta U and less than or equal to delta 3.

4. The feedback control system based on the PWM energy fed converter according to claim 3, wherein said adjusting means comprises:

the no-load voltage comparison module is used for starting the PWM energy feedback converter and feeding back the energy of the direct current contact network to the alternating current power grid if the voltage change value delta U is greater than 0, the absolute value delta 2 of the voltage change value is less than delta U and less than or equal to delta 3, and the direct current voltage value is greater than the no-load voltage value of the direct current contact network;

the converter voltage comparison module is used for starting the PWM energy feedback converter and feeding back the energy of a direct current contact net to an alternating current power grid if the voltage change value delta U is greater than 0, the absolute value delta 2 of the voltage change value is less than delta U and less than or equal to delta 3, and the direct current voltage value is greater than the preset voltage threshold value of the PWM energy feedback converter;

and the voltage change value comparison module is used for positively increasing the threshold value of the starting voltage and keeping the PWM energy-fed converter in a standby state if the voltage change value is 0 and less than or equal to delta U and less than or equal to delta 1, and reversely reducing the threshold value of the starting voltage and keeping the PWM energy-fed converter in the standby state if the voltage change value is less than or equal to delta U and less than or equal to 0.

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