CN110703138B - Ground fault detection method and device for traction system of motor train unit - Google Patents
Ground fault detection method and device for traction system of motor train unit Download PDFInfo
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- CN110703138B CN110703138B CN201911005619.0A CN201911005619A CN110703138B CN 110703138 B CN110703138 B CN 110703138B CN 201911005619 A CN201911005619 A CN 201911005619A CN 110703138 B CN110703138 B CN 110703138B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L9/00—Electric propulsion with power supply external to the vehicle
- B60L9/16—Electric propulsion with power supply external to the vehicle using ac induction motors
- B60L9/24—Electric propulsion with power supply external to the vehicle using ac induction motors fed from ac supply lines
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
- B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
- B60L3/0069—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to the isolation, e.g. ground fault or leak current
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L50/00—Electric propulsion with power supplied within the vehicle
- B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
- B60L50/51—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells characterised by AC-motors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2200/00—Type of vehicles
- B60L2200/26—Rail vehicles
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Abstract
The invention relates to a method and a device for detecting ground fault of a traction system of a motor train unit, wherein the method comprises the following steps: s1, acquiring the grounding voltage and the intermediate direct-current bus voltage of the traction system in real time, and calculating the average value of the grounding voltage and the grounding fault zone bit; s2, judging the position of the traction system with the ground fault by judging whether the intermediate DC bus voltage is larger than a preset value, the ground fault flag bit is '1' or '0' and the delay time after blocking the inverter pulse, or judging whether the intermediate DC bus voltage is larger than the preset value and whether the ratio of the average value of the ground voltage to the intermediate DC bus voltage is larger than the high threshold value of the ground fault or smaller than the low threshold value of the ground fault, and blocking different pulses according to different ground faults to disconnect different contactors or circuit breakers to finish the detection. The method can quickly judge the ground fault of the traction system, can accurately detect the occurrence position of the ground fault, and reduces the harmful influence of the ground fault on the traction system equipment.
Description
Technical Field
The invention belongs to the technical field of fault detection, relates to a ground fault detection technology of a rail train traction system, and particularly relates to a ground fault detection method and device of a motor train unit traction system.
Background
At present, the train of the motor train unit becomes the dominant passenger train of the high-speed railway, the express railway and the intercity railway in China, and plays a great role in ensuring the rapid development of national economy, promoting social progress and sustainable development. The traction system is used as the heart of the train of the motor train unit, and the main load converts electric energy on a contact net into kinetic energy of the train to provide traction power for the train. The ground fault may be caused by aging of components, vibration friction of cables, etc. during operation of the traction system. If one point is grounded, the influence on the normal operation of the traction system is small, but if two points are grounded or multiple points are grounded, a large short-circuit current can be generated, and the burning loss of the components of the traction system is caused.
The existing ground fault detection method for the traction system of the motor train unit mainly comprises the steps of comparing a ground voltage value detected by a voltage sensor with a voltage value of the traction system during normal work, judging that the traction system has a ground fault if the difference value of the ground voltage value and the voltage value exceeds a preset value, blocking a traction converter pulse, and disconnecting a train main circuit breaker. The existing ground fault detection method has the following problems:
(1) when the traction system has a ground fault, the position of the ground fault cannot be automatically positioned, and each device of the traction system needs to be manually overhauled, so that the fault treatment difficulty is high, and the period is long.
(2) When the traction system has ground fault, the protection actions with different severity degrees can not be adopted according to the ground fault of different traction system equipment, and the protection means is single.
Chinese patent publication No. 106680660B discloses a method for detecting a ground fault of a traction assistance system of an ac electric locomotive, the method comprising: acquiring voltage detected by a voltage sensor, and judging whether the traction auxiliary system has ground fault according to the voltage detected by the voltage sensor; and if the ground fault occurs, matching the voltage detected by the voltage sensor with a pre-stored ground voltage, and determining a corresponding ground fault point according to the matched ground voltage, wherein the pre-stored ground voltage is the ground voltage corresponding to the ground fault point when the ground fault occurs in the traction auxiliary system. However, in the ground detection method, all ground voltages corresponding to all points where ground faults may occur in the traction auxiliary system need to be stored in advance, and when the ground voltages are matched, the positions where the ground faults occur are determined according to the corresponding relation between the ground voltages and the ground points. Therefore, the method needs to store a large amount of grounding voltage data in a local storage chip in advance, so that the occupied resource is large, and the process of matching grounding voltages of different grounding fault points is relatively complex.
Disclosure of Invention
Aiming at the defects of difficult location of the ground fault, single protection means and the like in the prior art, the invention provides the ground fault method and the device for the traction system of the motor train unit, which can quickly judge the ground fault of the traction system, accurately detect the occurrence position of the ground fault and reduce the harmful influence of the ground fault on the traction system equipment.
In order to achieve the aim, the invention provides a method for detecting the ground fault of a traction system of a motor train unit, which comprises the following steps:
s1, acquiring the grounding voltage and the intermediate direct-current bus voltage of the traction system in real time, and calculating the average value of the grounding voltage and the grounding fault zone bit;
s2, judging the position of the traction system with the ground fault by judging whether the intermediate DC bus voltage is larger than a preset value, the ground fault flag bit is '1' or '0' and the delay time after blocking the inverter pulse, or judging whether the intermediate DC bus voltage is larger than the preset value and whether the ratio of the average value of the ground voltage to the intermediate DC bus voltage is larger than the high threshold value of the ground fault or smaller than the low threshold value of the ground fault, and blocking different pulses according to different ground faults to disconnect different contactors or circuit breakers to finish the detection.
Preferably, in step S1, the FPGA is used to calculate the average value of the ground voltage and the ground fault flag.
Preferably, in step S2, the specific method for determining the position of the traction system where the ground fault occurs, blocking different pulses according to different ground faults, and disconnecting different contactors or circuit breakers includes:
s21, when the voltage of the intermediate direct current bus is larger than the preset value, if the ground fault flag bit is 1 and the T1 time is maintained, the traction system is considered to have ground fault, the traction inverter pulse is blocked, the step S22 is skipped, and otherwise, the judgment is returned to continue; when the voltage of the middle direct current bus is larger than a preset value, the ratio of the average value of the voltage of the ground fault to the voltage of the middle direct current bus is larger than a high threshold value of the ground fault and is maintained for T2 time, the positive pole ground fault of the middle direct current bus in the traction converter is considered, pulses of the traction converter and the auxiliary converter are blocked, and a main contactor and a charging contactor of the traction converter are disconnected to finish detection; when the voltage of the middle direct current bus is larger than a preset value, the ratio of the average value of the voltage of the ground fault to the voltage of the middle direct current bus is smaller than a low threshold value of the ground fault and is maintained for T3 time, the ground fault is regarded as the negative pole ground fault of the middle direct current bus in the traction converter, the pulse of the traction converter and the pulse of the auxiliary converter are blocked, the main contactor and the charging contactor of the traction converter are disconnected, and the detection is finished;
s22, when the traction inverter pulse is blocked for the time of T4, if the ground fault flag bit is 1 and the time is maintained for T1, the auxiliary inverter pulse is blocked, and the step S23 is skipped; if the grounding fault flag bit is 0, the traction motor side is considered to be grounded, and detection is finished;
s23, when the auxiliary inverter blocks the time delay T5, if the grounding fault flag bit is 1 and the time is maintained for T1, the secondary side of the traction transformer is considered to be grounded, the traction converter pulse is blocked, the train main circuit breaker VCB is disconnected, and the detection is completed; and if the grounding fault flag bit is 0, the high-voltage side of the auxiliary inverter is considered to be grounded, the traction inverter pulse is restarted, the auxiliary inverter pulse is kept blocked, and the detection is finished.
In order to achieve the above object, the present invention further provides a ground fault detection device for a traction system of a motor train unit, comprising:
the voltage acquisition unit is used for acquiring the grounding voltage and the intermediate direct-current bus voltage of the traction system;
the calculation module is used for calculating the average value of the grounding voltage and the grounding fault zone bit;
and the judgment control module is used for judging the position of the traction system with the ground fault according to the average value of the ground voltage, the voltage of the intermediate direct-current bus, the ground fault zone bit and the delay time after pulse blocking, and blocking different pulses according to different ground faults to disconnect different contactors or circuit breakers.
Preferably, the voltage acquisition unit includes a ground voltage sensor for detecting a ground voltage and an intermediate dc bus voltage sensor for detecting an intermediate dc bus voltage.
The system further comprises an FPGA, the computing module is arranged in the FPGA, and the grounding voltage sensor and the middle direct-current bus voltage sensor are electrically connected with the FPGA.
The system further comprises a processor, the judgment control module is arranged in the processor, and the FPGA is connected with the processor.
Preferably, after the ground fault position is determined by the determination control module, the following three protection conditions are adopted:
if the traction system has a ground fault, blocking traction inverter pulses, blocking time delay T4 time when the traction inverter pulses block, blocking auxiliary inverter pulses if the ground fault flag bit is 1 and maintains T1 time, and when the auxiliary inverter blocks time delay T5 time and the ground fault flag bit is 1 and maintains T1 time, considering that the secondary side of the traction transformer is grounded, blocking the traction converter pulses and disconnecting a train main circuit breaker VCB; if the grounding fault flag bit is 0, the high-voltage side of the auxiliary inverter is considered to be grounded, the traction inverter pulse is restarted, and the auxiliary inverter pulse is kept blocked;
if the positive bus inside the traction converter has a ground fault, blocking the pulses of the traction converter and the auxiliary converter, and disconnecting the main contactor and the charging contactor of the traction converter;
and if the negative bus in the traction converter has a ground fault, blocking the pulse of the traction converter and the auxiliary converter, and disconnecting the main contactor and the charging contactor of the traction converter.
Compared with the prior art, the invention has the beneficial effects that:
(1) the method comprises the steps of judging whether a traction system has a ground fault according to the intermediate direct current bus voltage, the average value of the ground voltage obtained by calculation and a ground fault flag bit, blocking traction inverter pulses and auxiliary inverter pulses in a time-sharing mode when the ground fault flag bit is 1, gradually judging possible fault positions of the traction inverter and the auxiliary inverter by judging whether the ground fault disappears before and after pulse blocking, and adopting protective measures of different degrees; when the ratio of the average value of the ground fault voltage to the voltage of the middle direct current bus exceeds or is lower than a ground fault threshold value, the ground fault of the positive or negative bus of the traction converter can be directly judged. According to the invention, when the ground fault is detected, the ground fault point can be accurately judged to be generated at the secondary side of the transformer, the direct current bus in the middle of the positive pole and the negative pole of the traction converter, the high voltage side of the auxiliary inverter and the motor side without being matched with the pre-stored ground voltage, so that the identification of all possible ground fault points in the traction converter is realized, different protection actions are taken according to the severity level of the ground fault, the operation safety of the high-speed motor train unit is improved, the overhaul efficiency of motor train section maintainers is improved, and the maintenance cost of the motor train unit train is reduced.
(2) The invention adopts the FPGA to calculate the ground fault flag bit, quickly judges whether the ground voltage exceeds a normal value, has low sensitivity to the resistance value of the divider resistor of the ground fault detection circuit, has relatively low detection complexity, shortens the detection time and has high detection reliability.
Drawings
FIG. 1 is a flow chart of a method for detecting ground faults of a traction system of a motor train unit according to an embodiment of the invention;
fig. 2 is a structural block diagram of a ground fault detection device of a traction system of a motor train unit according to an embodiment of the invention.
FIG. 3 is an electrical schematic diagram of a traction system of a motor train unit according to an embodiment of the invention;
FIG. 4a is a diagram illustrating a ground voltage waveform when no ground fault occurs according to an embodiment of the present invention;
FIG. 4b is a diagram of the ground voltage waveform when the secondary side of the traction transformer, the traction motor side and the high-voltage side of the auxiliary inverter have ground faults according to the embodiment of the invention;
FIG. 4c is a waveform diagram of the ground voltage when the positive electrode of the intermediate DC bus has a ground fault according to the embodiment of the present invention;
FIG. 4d is a waveform diagram of the ground voltage when the negative electrode of the intermediate DC bus has a ground fault according to the embodiment of the present invention.
In the figure, 100, a traction transformer, 200, a traction converter, 201, a four-quadrant rectifier, 202, a traction inverter, 203, an auxiliary inverter, 204, a grounding detection circuit, 205, a switching component circuit, 300, a traction motor, 1, a voltage acquisition unit, 2, a grounding voltage sensor, 3, an intermediate direct current bus voltage sensor, 4, a calculation module, 5, a judgment control module, 6, an FPGA, 7 and a processor are included.
Detailed Description
The invention is described in detail below by way of exemplary embodiments. It should be understood, however, that elements, structures and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
In the process of detecting the ground fault of the traction system of the existing motor train unit train, when the ground fault of the traction system is detected, the position of the ground fault cannot be automatically positioned, and protective actions with different severity degrees cannot be taken according to the ground fault of different traction system equipment, so that the protective means is single.
In order to solve the above problem, an embodiment of the present invention provides a method for detecting a fault of a train traction system of a motor train unit, referring to fig. 1, which includes the following specific steps:
and S1, acquiring the grounding voltage and the intermediate direct-current bus voltage of the traction system, and calculating the average value of the grounding voltage and the grounding fault zone bit.
Specifically, the FPGA is adopted to calculate the average value of the grounding voltage and the grounding fault zone bit. The field programmable gate array FPGA is used for calculating the ground fault zone bit, whether the ground voltage exceeds a normal value or not can be judged quickly, the sensitivity to the resistance value of a divider resistor of a ground fault detection circuit is low, the detection complexity is relatively low, the detection time is effectively shortened, and the detection reliability is high.
S2, judging the position of the traction system with the ground fault by judging whether the intermediate DC bus voltage is larger than a preset value, the ground fault flag bit is '1' or '0' and the delay time after blocking the inverter pulse, or judging whether the intermediate DC bus voltage is larger than the preset value and whether the ratio of the average value of the ground voltage to the intermediate DC bus voltage is larger than the high threshold value of the ground fault or smaller than the low threshold value of the ground fault, and blocking different pulses according to different ground faults to disconnect different contactors or circuit breakers to finish the detection. Specifically, the specific method of judging the position of the traction system with the ground fault, blocking different pulses according to different ground faults and disconnecting different contactors or circuit breakers includes:
s21, when the voltage of the intermediate direct current bus is larger than the preset value, if the ground fault flag bit is 1 and the T1 time is maintained, the traction system is considered to have ground fault, the traction inverter pulse is blocked, the step S22 is skipped, and otherwise, the judgment is returned to continue; when the voltage of the middle direct current bus is larger than a preset value, the ratio of the average value of the voltage of the ground fault to the voltage of the middle direct current bus is larger than a high threshold value of the ground fault and is maintained for T2 time, the ground fault is regarded as the ground fault of the positive pole bus in the traction converter, the pulse of the traction converter and the pulse of the auxiliary converter are blocked, the main contactor and the charging contactor of the traction converter are disconnected, and the detection is finished; when the voltage of the middle direct current bus is larger than the preset value, the ratio of the average value of the ground fault voltage to the voltage of the middle direct current bus is smaller than the low threshold value of the ground fault and is maintained for T3 time, the ground fault is considered to be the ground fault of the negative bus in the traction converter, pulses of the traction converter and the auxiliary converter are blocked, the main contactor and the charging contactor of the traction converter are disconnected, and detection is completed.
S22, when the traction inverter pulse is blocked for the time of T4, if the ground fault flag bit is 1 and the time is maintained for T1, the auxiliary inverter pulse is blocked, and the step S23 is skipped; and if the grounding fault flag bit is 0, the traction motor side is considered to be grounded, and the detection is completed.
S23, when the auxiliary inverter blocks the time delay T5, if the grounding fault flag bit is 1 and the time is maintained for T1, the secondary side of the traction transformer is considered to be grounded, the traction converter pulse is blocked, the train main circuit breaker VCB is disconnected, and the detection is completed; and if the grounding fault flag bit is 0, the high-voltage side of the auxiliary inverter is considered to be grounded, the traction inverter pulse is restarted, the auxiliary inverter pulse is kept blocked, and the detection is finished.
According to the steps, whether the ground fault occurs in the traction system can be judged according to the intermediate direct current bus voltage and the FPGA, the ground fault flag bit and the ratio of the average value of the ground voltage to the intermediate direct current bus voltage are calculated, when the ground fault flag bit is 1, the traction inverter and the auxiliary inverter are blocked in a time-sharing mode, the possible position of a ground fault point is gradually judged according to whether the ground fault disappears before and after pulse blocking, protective measures of different degrees are taken, and when the ratio of the average value of the ground voltage to the intermediate direct current bus voltage exceeds or is lower than a ground fault threshold, the positive pole or the negative pole of the bus of the traction converter can be judged to have the ground fault. The method and the device realize the identification of all possible ground faults in the traction converter, adopt different protection actions according to the severity level of the ground fault, effectively improve the operation safety of the motor train unit train, improve the overhauling efficiency of motor train unit section maintainers, and have low maintenance cost.
Specifically, in the detection method of the present invention, the times T1, T2, T3, T4, and T5 are set times, and can be set according to actual requirements. For example: t1 may be 0.1s, T2, T3 may be 0.5s, T4, T5 may be 0.2 s. The ground fault threshold may also be set just after the actual requirement, for example: the ground fault high threshold may be 0.75 and the ground fault low threshold may be 0.15.
The detection method can quickly judge the ground fault of the traction system, can accurately detect the occurrence position of the ground fault, reduces the harmful influence of the ground fault on the traction equipment, and improves the maintenance efficiency of maintenance personnel.
Referring to fig. 2, another embodiment of the present invention provides a ground fault detection device for a traction system of a motor train unit, including:
the voltage acquisition unit 1 is used for acquiring the grounding voltage and the intermediate direct-current bus voltage of the traction system;
the calculation module 4 is used for calculating the average value of the grounding voltage and the grounding fault zone bit;
and the judgment control module 5 is used for judging the position of the traction system with the ground fault according to the average value of the ground voltage, the voltage of the intermediate direct-current bus, the ground fault zone bit and the delay time after pulse blocking, and blocking different pulses according to different ground faults to disconnect different contactors or circuit breakers.
Specifically, with continued reference to fig. 2, the voltage acquisition unit 1 includes a ground voltage sensor 2 for detecting a ground voltage and an intermediate dc bus voltage sensor 3 for detecting an intermediate dc bus voltage.
Specifically, the detection device further comprises an FPGA 6, the calculation module 4 is arranged in the FPGA 6, and the ground voltage sensor 2 and the intermediate direct-current bus voltage sensor 3 are electrically connected with the FPGA 6. The method adopts the field programmable gate array FPGA to calculate the ground fault zone bit, can quickly judge whether the ground voltage exceeds a normal value, has low sensitivity to the resistance value of a divider resistor of a ground fault detection circuit, has relatively low detection complexity, effectively shortens the detection time and has high detection reliability.
Specifically, the detection device further includes a processor 7, the judgment control module 5 is disposed in the processor 7, and the FPGA 6 is connected to the processor 7. In this embodiment, the processor is a CPU or an MCU.
Specifically, in the process of performing ground fault judgment control by the judgment control module, after the judgment control module judges the ground fault position, the following three protection conditions are adopted:
if the traction system has a ground fault, blocking traction inverter pulses, blocking time delay T4 time when the traction inverter pulses block, blocking auxiliary inverter pulses if the ground fault flag bit is 1 and maintains T1 time, and when the auxiliary inverter blocks time delay T5 time and the ground fault flag bit is 1 and maintains T1 time, considering that the secondary side of the traction transformer is grounded, blocking the traction converter pulses and disconnecting a train main circuit breaker VCB; if the grounding fault flag bit is 0, the high-voltage side of the auxiliary inverter is considered to be grounded, the traction inverter pulse is restarted, and the auxiliary inverter pulse is kept blocked; specifically, the times T1, T4, and T5 are set times, and can be set according to actual needs. For example: t1 may be 0.1s, T4, T5 may be 0.2 s.
If the positive bus inside the traction converter has a ground fault, blocking the pulses of the traction converter and the auxiliary converter, and disconnecting the main contactor and the charging contactor of the traction converter;
and if the negative bus in the traction converter has a ground fault, blocking the pulse of the traction converter and the auxiliary converter, and disconnecting the main contactor and the charging contactor of the traction converter.
The detection device can accurately judge the position of the ground fault point, and takes different protection actions according to the severity level of the ground fault, thereby effectively improving the running safety of the motor train unit train, improving the overhauling efficiency of the maintainers and reducing the maintenance cost.
To further illustrate the advantages of the above-described method and apparatus of the present invention, the present invention is further described below with reference to the accompanying drawings and examples.
Example (b): referring to fig. 3, a traction system of a certain motor train unit comprises a traction transformer 100, a traction converter 200 and a traction motor 300 which are connected in sequence, wherein the traction converter 200 comprises a four-quadrant rectifier 201, a traction inverter 202, an auxiliary inverter 203, a grounding detection circuit 204 and a switching component circuit 205.
The traction transformer 100 converts the 25kV alternating current of the contact network into 950V alternating current to enter the traction converter 200. The switch component 205 pre-charges and uncontrollably rectifies the 950V alternating current into 1343V direct current, and large current impact of an intermediate direct current bus circuit is avoided. The four-quadrant rectifier 201 rectifies the 950V ac to 1850V dc, powering the traction inverter 202 and the auxiliary inverter 203. The traction inverter 202 inverts 1850V DC power to three-phase AC power with controllable voltage and frequency to drive the traction motor 300. The auxiliary inverter 203 inverts 1850V direct current into 550V/50Hz three-phase alternating current, and then the three-phase alternating current is converted into 380V/50Hz alternating current through an auxiliary transformer to supply power for medium-voltage loads of the train.
The ground detection circuit 204 is composed of two resistors with a resistance value of 1:1, a filter capacitor and a voltage sensor U33, and is used for detecting whether a ground fault occurs in the traction system. When the traction system is working normally, the grounding voltage detected by the voltage sensor U33 is half 925V of the intermediate dc bus voltage theoretically, and actually, due to the fast on/off of the power devices of the four-quadrant rectifier 201 and the traction inverter 202, the grounding voltage fluctuates above and below the normal value 925V through the distributed capacitance and the stray inductance in the traction converter 200, as shown in fig. 4 a. When the traction system has a ground fault, the ground voltage detected by the voltage sensor U33 deviates from the normal ground voltage.
According to the occurrence position of a ground fault point in the traction system, the ground faults are divided into a secondary side ground fault of a traction transformer, a positive pole ground fault of an intermediate direct current bus, a negative pole ground fault of the intermediate direct current bus, a high-voltage side ground fault of an auxiliary inverter and a side ground fault of a traction motor. Continuing to refer to fig. 3, the ground faults occurring at points 1, 2, 3 and 4 in the main circuit belong to the secondary side ground fault of the traction transformer, the ground fault occurring at point 5 in the main circuit belongs to the positive pole ground fault of the intermediate direct current bus, the ground fault occurring at point 6 in the main circuit belongs to the negative pole ground fault of the intermediate direct current bus, the ground faults occurring at points 7, 8 and 9 in the main circuit belong to the high-voltage side ground fault of the auxiliary inverter, and the ground faults occurring at points 10, 11, 12, 13, 14 and 15 in the main circuit belong to the traction motor side ground fault.
The above 5 types of ground faults can be classified into the following three types according to the ground voltage waveform when the ground fault occurs:
the first category includes a traction transformer secondary side ground fault, an auxiliary inverter high voltage side ground fault and a traction motor side ground fault, referring to fig. 4b, the ground voltage waveform is a PWM pulse type, the pulse amplitude is an intermediate dc bus voltage 1850V, and the pulse frequency is different according to the ground point where the ground fault occurs. When a secondary side ground fault of the traction transformer occurs, the pulse frequency of the ground voltage is equal to the switching frequency of the four-quadrant rectifier 201; when the auxiliary inverter high-voltage side ground fault occurs, the ground voltage pulse frequency is equal to the switching frequency of the auxiliary inverter 203; when a traction motor side ground fault occurs, the ground voltage pulse frequency is equal to the switching frequency of the traction inverter 202. In this embodiment, the switching frequency of the four-quadrant rectifier 201 is 350Hz, the switching frequency of the auxiliary inverter 203 is 1050Hz, and the switching frequency of the traction inverter 202 varies within a range of 110Hz to 550 Hz.
The second type is the intermediate dc bus positive ground fault, the ground voltage is equal to the intermediate dc bus voltage 1850V, see fig. 4c, the ground voltage is linear, and the voltage is the intermediate dc bus voltage 1850V.
The third type is an intermediate dc bus negative ground fault with ground voltage equal to 0V, see fig. 4 d.
The detection method and the detection device of the invention are used for detecting the ground fault of the traction system of the motor train unit, and the detection method comprises the following specific steps:
and S1, acquiring the grounding voltage detected by a grounding voltage sensor (namely the voltage sensor U33 in the traction system) and the intermediate direct current bus voltage detected by an intermediate direct current bus voltage sensor (namely the voltage sensor U32 in the traction system), and calculating a grounding voltage average value and a grounding fault bit by using a calculation module in the FPGA.
In this embodiment, the ground voltage average value is filtered by a moving average value with a time length of 20ms, and the condition of the ground fault flag position 1 is as follows: the grounding voltage is larger than 1600V, and the condition of the grounding fault mark position 0 is as follows: the ground voltage is less than 1300V.
S2, judging the position of the traction system with the ground fault, blocking different pulses according to different ground faults, and disconnecting different contactors or circuit breakers, wherein the method comprises the following specific steps:
s21, when the intermediate direct-current bus voltage is larger than the preset value, if the ground fault flag bit is 1 and the time T1 is maintained to be 0.1S, the traction system is considered to have a ground fault, the traction inverter 202 pulse is blocked, the step S22 is skipped, and otherwise, the judgment is returned to continue; when the intermediate direct-current bus voltage is greater than the preset value, the ratio of the average value of the ground fault voltage to the intermediate direct-current bus voltage is greater than the ground fault high threshold value of 0.75 and the time T2 is maintained to be 0.5s, the ground fault of the positive bus inside the traction converter 200 is considered, the pulses of the four-quadrant rectifier 201, the traction converter 202 and the auxiliary converter 203 are blocked, the main contactor and the charging contactor of the switch component circuit 205 are disconnected, and the detection is completed; when the intermediate direct-current bus voltage is larger than the preset value, the ratio of the average value of the ground fault voltage to the intermediate direct-current bus voltage is smaller than the low threshold value of the ground fault by 0.15 and the time T3 is maintained to be 0.5s, the ground fault is considered to be the ground fault of the negative bus in the traction converter 200, the pulses of the four-quadrant rectifier 201, the traction converter 202 and the auxiliary converter 203 are blocked, the main contactor and the charging contactor of the switch component circuit 205 are disconnected, and the detection is completed.
S22, when the pulse blocking delay T4 of the traction inverter 202 is 0.2S, and if the ground fault flag is 1 and the time T1 is maintained to be 0.1S, the pulse of the auxiliary inverter 203 is blocked, and the process goes to step S23; if the ground fault flag is 0, the traction motor 300 is considered to be grounded, and the detection is completed.
S23, when the auxiliary inverter 203 blocks the time delay T5 is 0.2S, and if the ground fault flag is 1 and the time T1 is maintained to be 0.1S, it is determined that the secondary side of the traction transformer is grounded, the traction converter pulse is blocked, the main contactor and the charging contactor of the switching component circuit 205 are disconnected, and the train main breaker VCB is disconnected, thereby completing the detection; if the ground fault flag is 0, the high-voltage side of the auxiliary inverter 203 is considered to be grounded, the traction inverter 202 is restarted to pulse, the pulse of the auxiliary inverter 203 is kept blocked, and the detection is finished.
Therefore, the detection method and the detection device provided by the invention realize the rapid judgment of the ground faults occurring in the traction system, can accurately detect the occurrence positions of all the ground faults, and then adopt different protective measures according to different severity levels, so that the harmful influence of the ground faults on the traction system is reduced, the ground faults do not need to be matched with the pre-stored grounding voltage, the detection process is simple, the detection time is short, the overhaul efficiency of maintainers is improved, the occupied resources are few, and the detection cost is low. The detection accuracy and reliability are obviously superior to those of the prior art.
The above-mentioned embodiments are merely provided for the convenience of illustration of the present invention, and do not limit the scope of the present invention, and various simple modifications and modifications made by those skilled in the art within the technical scope of the present invention should be included in the above-mentioned claims.
Claims (6)
1. A method for detecting ground fault of a traction system of a motor train unit is characterized by comprising the following steps:
s1, acquiring the grounding voltage and the intermediate direct-current bus voltage of the traction system, and calculating the average value of the grounding voltage and the grounding fault zone bit;
s2, judging the position of the traction system with the ground fault by judging whether the intermediate DC bus voltage is greater than a preset value, the ground fault flag bit is '1' or '0' and the delay time after blocking the inverter pulse, or judging whether the intermediate DC bus voltage is greater than the preset value and whether the ratio of the average value of the ground voltage to the intermediate DC bus voltage is greater than the high threshold value of the ground fault or less than the low threshold value of the ground fault, and blocking different pulses according to different ground faults, and disconnecting different contactors or circuit breakers to finish the detection;
the specific method for judging the position of the traction system with the ground fault, blocking different pulses according to different ground faults and disconnecting different contactors or circuit breakers comprises the following steps:
s21, when the voltage of the intermediate direct current bus is larger than the preset value, if the ground fault flag bit is 1 and the T1 time is maintained, the traction system is considered to have ground fault, the traction inverter pulse is blocked, the step S22 is skipped, and otherwise, the judgment is returned to continue; when the voltage of the middle direct-current bus is larger than a preset value, the ratio of the average value of the grounding voltage to the voltage of the middle direct-current bus is larger than a grounding fault high threshold value and is maintained for T2 time, the grounding fault of the positive electrode of the middle direct-current bus in the traction converter is considered, pulses of the traction converter and the auxiliary converter are blocked, and a main contactor and a charging contactor of the traction converter are disconnected to finish detection; when the voltage of the middle direct current bus is larger than a preset value, the ratio of the average value of the grounding voltage to the voltage of the middle direct current bus is smaller than the low threshold value of the grounding fault and is maintained for T3 time, the grounding fault is considered to be the grounding fault of the negative electrode of the middle direct current bus in the traction converter, the pulses of the traction converter and the auxiliary converter are blocked, the main contactor and the charging contactor of the traction converter are disconnected, and the detection is finished;
s22, when the traction inverter pulse is blocked for the time of T4, if the ground fault flag bit is 1 and the time is maintained for T1, the auxiliary inverter pulse is blocked, and the step S23 is skipped; if the grounding fault flag bit is 0, the traction motor side is considered to be grounded, and detection is finished;
s23, when the auxiliary inverter blocks the time delay T5, if the grounding fault flag bit is 1 and the time is maintained for T1, the secondary side of the traction transformer is considered to be grounded, the traction converter pulse is blocked, the train main circuit breaker VCB is disconnected, and the detection is completed; and if the grounding fault flag bit is 0, the high-voltage side of the auxiliary inverter is considered to be grounded, the traction inverter pulse is restarted, the auxiliary inverter pulse is kept blocked, and the detection is finished.
2. The method for detecting the ground fault of the traction system of the motor train unit according to claim 1, wherein in step S1, the ground voltage average value and the ground fault flag are calculated by using an FPGA.
3. The utility model provides a EMUs traction system ground fault detection device which characterized in that includes:
the voltage acquisition unit is used for acquiring the grounding voltage and the intermediate direct-current bus voltage of the traction system;
the calculation module is used for calculating the average value of the grounding voltage and the grounding fault zone bit;
the judgment control module is used for judging the position of the traction system with the ground fault according to the average value of the ground voltage, the voltage of the intermediate direct-current bus, the ground fault zone bit and the delay time after pulse blocking, blocking different pulses according to different ground faults and disconnecting different contactors or circuit breakers; the specific method for judging the position of the traction system with the ground fault, blocking different pulses according to different ground faults and disconnecting different contactors or circuit breakers comprises the following steps:
s21, when the voltage of the intermediate direct current bus is larger than the preset value, if the ground fault flag bit is 1 and the T1 time is maintained, the traction system is considered to have ground fault, the traction inverter pulse is blocked, the step S22 is skipped, and otherwise, the judgment is returned to continue; when the voltage of the middle direct-current bus is larger than a preset value, the ratio of the average value of the grounding voltage to the voltage of the middle direct-current bus is larger than a grounding fault high threshold value and is maintained for T2 time, the grounding fault of the positive electrode of the middle direct-current bus in the traction converter is considered, pulses of the traction converter and the auxiliary converter are blocked, and a main contactor and a charging contactor of the traction converter are disconnected to finish detection; when the voltage of the middle direct current bus is larger than a preset value, the ratio of the average value of the grounding voltage to the voltage of the middle direct current bus is smaller than the low threshold value of the grounding fault and is maintained for T3 time, the grounding fault is considered to be the grounding fault of the negative electrode of the middle direct current bus in the traction converter, the pulses of the traction converter and the auxiliary converter are blocked, the main contactor and the charging contactor of the traction converter are disconnected, and the detection is finished;
s22, when the traction inverter pulse is blocked for the time of T4, if the ground fault flag bit is 1 and the time is maintained for T1, the auxiliary inverter pulse is blocked, and the step S23 is skipped; if the grounding fault flag bit is 0, the traction motor side is considered to be grounded, and detection is finished;
s23, when the auxiliary inverter blocks the time delay T5, if the grounding fault flag bit is 1 and the time is maintained for T1, the secondary side of the traction transformer is considered to be grounded, the traction converter pulse is blocked, the train main circuit breaker VCB is disconnected, and the detection is completed; and if the grounding fault flag bit is 0, the high-voltage side of the auxiliary inverter is considered to be grounded, the traction inverter pulse is restarted, the auxiliary inverter pulse is kept blocked, and the detection is finished.
4. The ground fault detection device of the traction system of the motor train unit according to claim 3, wherein the voltage acquisition unit comprises a ground voltage sensor for detecting a ground voltage and an intermediate direct current bus voltage sensor for detecting an intermediate direct current bus voltage.
5. The ground fault detection device of the traction system of the motor train unit according to claim 4, further comprising an FPGA, wherein the calculation module is arranged in the FPGA, and the ground voltage sensor and the intermediate direct-current bus voltage sensor are electrically connected with the FPGA.
6. The ground fault detection device of the traction system of the motor train unit according to claim 5, further comprising a processor, wherein the judgment control module is arranged in the processor, and the FPGA is connected with the processor.
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| CN111766534B (en) * | 2020-06-07 | 2021-07-13 | 中车永济电机有限公司 | Traction converter ground fault detection method and device |
| CN114002615B (en) * | 2020-07-28 | 2023-02-28 | 株洲中车时代电气股份有限公司 | Method and device for diagnosing converter ground fault |
| CN112098890B (en) * | 2020-09-16 | 2023-04-28 | 中车青岛四方车辆研究所有限公司 | Alternating-current grounding fault detection method for parallel auxiliary converters of motor train unit |
| CN112421578A (en) * | 2020-11-03 | 2021-02-26 | 中车青岛四方机车车辆股份有限公司 | Fault processing method, device and system of traction converter and related equipment |
| DE102020216215A1 (en) * | 2020-12-18 | 2022-06-23 | Siemens Mobility GmbH | Vehicle, in particular a rail vehicle, with a DC link |
| CN113002333B (en) * | 2021-03-24 | 2022-07-19 | 清华大学 | High-power converter grounding method of full-through type flexible alternating current traction power supply system |
| CN117233662B (en) * | 2023-11-13 | 2024-01-23 | 江苏新誉阿尔斯通牵引系统有限公司 | Grounding point detection method for subway multi-converter parallel traction transmission system |
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