CN-122008865-A - Control method and system for preventing intermediate capacitance overvoltage when train passes through dead zone

CN122008865ACN 122008865 ACN122008865 ACN 122008865ACN-122008865-A

Abstract

The invention provides a control method and a system for preventing an intermediate capacitor from overvoltage when a train passes through a dead zone, wherein the method comprises the steps of S1 monitoring the running speed of the train in real time, executing S2 when the speed is lower than a preset threshold value and a traction system diagnoses an undervoltage fault, S2 detecting whether the intermediate capacitor voltage reaches a chopping-on threshold in a network voltage recovery process, executing S3 if the intermediate capacitor voltage reaches the chopping-on threshold, S3 switching on a brake chopper and starting a time control mechanism, wherein the control mechanism comprises single chopping-on time and accumulated chopping time from undervoltage to network voltage recovery, and judging in parallel in the chopping process, and immediately switching off the chopper when the single chopping time exceeds a first allowable time or the accumulated chopping time exceeds a second allowable time. According to the invention, through a double time control mechanism, the overvoltage of the intermediate capacitor is effectively prevented under the condition that the brake resistor is not subjected to forced air cooling, the smooth transition from the non-electric area to the electric area of the system is ensured, and the overvoltage protection problem caused by the disabling of the micro brake function under the low-speed working condition is solved.

Inventors

LU YUANJI
DENG JING
TANG JIACHENG
WU YUNFEI
CHEN KE
WANG LONG
MOU RONG
ZHU DONGPO
WEI ZHOUYAN
HE TAO
GAO ZHENGLIANG

Assignees

株洲中车时代电气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20251027

Claims (9)

1. A control method for preventing overvoltage of intermediate capacitor when train passes through no-electricity zone, comprising the steps of: step S1, monitoring the running speed of a train in real time, and executing step S2 when the running speed of the train is lower than a preset speed threshold value and the undervoltage fault is diagnosed by a traction reverse system; Step S2, detecting whether the voltage of the intermediate capacitor reaches a chopping-on threshold or not in the network voltage recovery process, if so, executing step S3, and if not, executing step S1; And step S3, controlling to turn on a brake chopper and starting a time control mechanism, wherein the time control mechanism comprises a single chopping turn-on time and an accumulated chopping time, the accumulated chopping time is the total chopping time from the undervoltage fault to the full network voltage recovery, in the chopping process, whether the single chopping turn-on time exceeds a first allowable time and whether the accumulated chopping time exceeds a second allowable time are judged in parallel, when the single chopping turn-on time exceeds the first allowable time or the accumulated chopping time exceeds any one of the second allowable time, the brake chopper is turned off, and the first allowable time and the second allowable time are set based on the heat capacity of a brake resistor.
2. The control method for preventing overvoltage of intermediate capacitor in a train passing through a dead zone according to claim 1, wherein when determining the second allowable time, a temperature rise process of a brake resistor is modeled as an adiabatic temperature rise process, and the second allowable time is calculated by an adiabatic temperature rise formula based on a dissipated power, a mass, a specific heat capacity, and an allowable temperature rise of the brake resistor.
3. The control method for preventing overvoltage of intermediate capacitor in a train passing through a dead zone according to claim 2, wherein in step S3, the second allowable time is calculated by the following formula: Wherein, the A second allowable time period is indicated and the second allowable time period, Indicating the mass of the resistive strip, Represents the specific heat capacity of the resistive material, Indicating that the braking resistor is dissipating power, Represents the heat exchange coefficient of the air, The surface area, x, is the temperature of the resistive band, The temperature of the air is set to be the air temperature, Indicating the initial temperature of the resistor band at the start of braking.
4. The method for controlling an intermediate capacitor to prevent an overvoltage in a train passing through a dead zone according to claim 1, wherein in step S3, the first allowable time is calculated based on a current voltage, a target voltage and a capacity value of the intermediate capacitor, energy to be consumed by the brake resistor is calculated, a chopping time range required for completing the energy consumption is determined according to a resistance value and a working voltage of the brake resistor, and the time range is used as a basis for setting the first allowable time.
5. The method of claim 4, wherein the single chopping on time is determined based on the principle of conservation of energy, which satisfies the following relationship: Wherein, the Representing the intermediate capacitance voltage value at the initial time; The value of the intermediate capacitance voltage at time t is indicated, And R is the resistance of the brake resistor, and t is the required single chopping turn-on time.
6. The control method for preventing overvoltage of intermediate capacitor in passing through no-electricity zone of train according to any one of claims 1-5, wherein during the brake chopper is on, brake resistor fan does not work, and said brake resistor is in no forced air cooling state.
7. A control system for preventing overvoltage of intermediate capacitance in a train passing through a dead zone comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to perform a control method for preventing overvoltage of intermediate capacitance in a train passing through a dead zone as claimed in any one of claims 1 to 6.
8. A computer readable storage medium having stored therein a computer program/instruction, the computer program/instruction being programmed or configured to execute a control method of preventing overvoltage of an intermediate capacitance when a train passes through a dead zone as claimed in any one of claims 1 to 6 by a processor.
9. A computer program product comprising computer program/instructions programmed or configured to, with a processor, perform the control method of any one of claims 1 to 6 for preventing overvoltage of intermediate capacitance when a train passes through a dead zone.

Description

Control method and system for preventing intermediate capacitance overvoltage when train passes through dead zone Technical Field The invention relates to the technical field of rail transit, in particular to a control method and a system for preventing overvoltage of an intermediate capacitor when a train passes through a dead zone. Background The power of the urban rail transit vehicle is derived from a traction system, and the system inverts the electric energy of a direct current overhead contact system (usually with the DC of 750V or 1500V) into three-phase variable-voltage variable-frequency (VVF) alternating current through a traction inverter so as to drive a traction motor, thereby realizing traction acceleration or electric braking deceleration of the train. According to the different power receiving modes, the power supply method mainly comprises a pantograph power supply mode and a third rail power supply mode. Wherein, limited by the physical layout of the third rail, in some special sections of the vehicle section/parking lot access line or positive line, there is a rail break zone of the third rail, i.e. a dead zone. When the train moves from the powered area to the unpowered area, the net pressure input to the traction system will disappear instantaneously. If the train is in the traction working condition at this time, the voltage of the middle supporting capacitor in the system can be rapidly reduced due to self-discharging. Once the voltage drops below the undervoltage protection threshold, the traction control system will trigger a protection action of tripping the shorting contactor and reporting an undervoltage fault. The process can simultaneously lead to the shutdown of the whole vehicle auxiliary inverter due to the undervoltage of input, so that all auxiliary loads such as air conditioner, illumination, ventilation and the like are powered off, and the operation quality of a train and the comfort level of passengers are affected. To address the above problems, the prior art often employs a "micro brake" solution. The basic principle is that the system monitors the network pressure in real time, and when detecting that the network pressure falls to reach a preset threshold in a very short time under a certain speed, the system immediately starts the micro-braking function. The function switches the traction motor from a motor state to a generator state, and the power energy converted from kinetic energy generated by the motor is rectified by controlling the on-off of an IGBT device in the inverter and fed back to a vehicle high-voltage loop. On the one hand, the intermediate capacitor can be charged to maintain the voltage level of the intermediate capacitor to prevent the intermediate capacitor from falling into an under-voltage protection zone, and on the other hand, the generated electric energy can be used by an auxiliary system to avoid the shutdown of an auxiliary inverter. However, this approach has significant limitations. Because of the limited length of the dead zone (particularly in the access section lines) and the low speed of operation of the train as it passes. If the micro-braking is started at a low speed, the generated braking moment can lead to the train to be decelerated and even stagnated in a dead zone, so that more serious operation accidents (such as train rescue) are caused. Thus, for safety reasons, the micro-braking function is disabled during low speed conditions. When the train is driven out of the non-electric area and the network voltage is recovered, the system re-closes the short-circuit contactor and the charging contactor in order to recover the power supply of the traction and auxiliary systems. In summary, the existing control strategy cannot realize stable and safe state switching in the whole process of low-speed passing through the no-power zone (especially at the moment of entering the power zone from the no-power zone), and falls into passive circulation of 'under-voltage when passing through the no-power zone and over-voltage when recovering power supply', thereby seriously affecting the running reliability of the vehicle. Disclosure of Invention The technical problem to be solved by the invention is as follows: aiming at the technical problems existing in the prior art, the invention provides a control method and a system for preventing an intermediate capacitor from overvoltage when a train passes through a dead zone, brake chopping is automatically started according to capacitor voltage in the network voltage recovery process by monitoring the working condition of low-speed undervoltage of the train, and a double time control mechanism of single chopping time and accumulated chopping time is adopted, so that the safety of a brake resistor is ensured while the intermediate capacitor is effectively prevented from overvoltage, and the stable transition of the train is realized. In order to solve the technical problems, the technical scheme