Alternating current catenary uninterrupted power supply anti-icing system and control method thereof
By introducing an anti-icing system using rectifiers and PWM inverters into the AC contact network and utilizing power from adjacent traction substations to generate a controllable anti-icing current, the problem of icing on the AC contact network under extreme weather conditions has been solved, ensuring the safe and efficient operation of the railway.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWEST JIAOTONG UNIV
- Filing Date
- 2026-05-15
- Publication Date
- 2026-07-31
AI Technical Summary
The existing AC overhead contact system is prone to icing in extreme weather, leading to mechanical and electrical failures and affecting railway transportation safety. Furthermore, existing anti-icing technologies suffer from low efficiency, high cost, or poor compatibility.
The anti-icing system, composed of a rectifier and a PWM inverter, draws power from an adjacent traction substation and uses quasi-proportional resonant control to generate a controllable anti-icing current, thus achieving uninterrupted power supply to the AC contact network to prevent icing.
It achieves efficient prevention of contact wire icing without affecting normal train operation, ensuring safe railway operation under extreme weather conditions, and reducing system complexity and cost.
Smart Images
Figure CN122495263A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrified railway traction power supply systems, and in particular to an AC contact network uninterrupted power supply and anti-icing system and its control method. Background Technology
[0002] With the rapid development of electrified railways in my country, railway transportation is moving towards high speed, heavy load, and intelligent operation, placing higher demands on the safety and reliability of traction power supply systems. As the direct power supply equipment for electric locomotives, the overhead contact line's operating status directly affects the stable current collection of trains and the efficiency of railway transportation. However, because the overhead contact line is an overhead, exposed structure, it is highly susceptible to icing under extreme weather conditions such as low temperatures, freezing rain, and snow in winter. Icing not only increases the mechanical load on the contact line but also triggers a series of electrical and mechanical faults, seriously threatening railway transportation safety. In recent years, global climate anomalies have intensified, and extreme snow and ice weather has become more frequent, making the problem of contact line icing increasingly prominent and one of the key factors restricting the stable operation of electrified railways in high-altitude and high-humidity regions.
[0003] The current mainstream solutions for contact network de-icing mainly include three categories: (1) Mechanical de-icing, which uses methods such as manual knocking, mechanical vibration and pantograph scraping. Although the equipment is simple, the efficiency is low and there are operational risks; (2) Chemical de-icing, which achieves preventive protection by coating hydrophobic coatings or spraying agents, but faces problems such as short coating life, high cost and environmental protection; (3) Thermal de-icing, which has the most promising development prospects. Among them, DC de-icing has the advantages of high efficiency and low capacity requirements, but there are limitations on implementation conditions; while AC de-icing technology has good compatibility with AC electrified railways, providing a solution that is both technologically advanced and economically feasible for railway operation in high-altitude and cold regions. Summary of the Invention
[0004] The purpose of this invention is to provide an anti-icing system and its control method that has high control precision, minimal impact on the contact network voltage, and enables uninterrupted power supply to the AC contact network.
[0005] The technical solution for implementing the present invention is as follows:
[0006] An AC contact network uninterrupted de-icing prevention system includes a rectifier and a PWM inverter connected in sequence; the output terminal of the PWM inverter is connected to the primary of a second transformer; one end of the secondary of the second transformer is connected to the upstream contact network for de-icing prevention via a second disconnecting switch and a second circuit breaker, and the other end is connected to the downstream contact network for de-icing prevention via a third disconnecting switch and a third circuit breaker, wherein the upstream and downstream contact networks for de-icing prevention are powered by a first traction substation; the input terminal of the rectifier is connected to the secondary of the first transformer; one end of the primary of the first transformer is connected to the upstream or downstream contact network powered by the second traction substation via a first disconnecting switch and a first circuit breaker, and the other end is grounded.
[0007] Preferably, the second traction substation is adjacent to the first traction substation.
[0008] The control method for the above-mentioned anti-icing system is as follows:
[0009] When the upstream and / or downstream contact networks of the anti-icing system meet the anti-icing or de-icing conditions, the parallel switches of the upstream and downstream contact networks are disconnected, and the first isolating switch, the first circuit breaker, the second isolating switch, the second circuit breaker, the third isolating switch, and the third circuit breaker are closed, so that the anti-icing system enters the anti-icing mode or the de-icing mode; the output current of the PWM inverter is sampled, and the current difference is calculated with the anti-icing current reference value or the de-icing current reference value. A PWM modulation signal is generated through quasi-proportional resonance control to control the PWM inverter.
[0010] Preferably, the anti-icing current reference value or de-icing current reference value is set according to the critical anti-icing current or critical de-icing current, and is less than or equal to the allowable current carrying capacity of the contact network.
[0011] Preferably, the anti-icing current reference value or de-icing current reference value is obtained by the following method:
[0012] S1. The optimal phase angle of the anti-icing current or de-icing current is obtained by enumeration. ,include:
[0013] S1.1 Set the initial value of the anti-icing current or de-icing current amplitude according to the critical anti-icing current or critical de-icing current. , Less than or equal to the allowable current carrying capacity of the overhead contact line; phase angle of the initial anti-icing current or de-icing current. Set the minimum value of the sum of the contact network voltage differences. ;make ;
[0014] S1.2, as If so, continue; otherwise, the current phase angle... The optimal phase angle;
[0015] S1.3 Calculate the anti-icing current or de-icing current:
[0016] ;
[0017] Calculate the output voltage of the anti-icing system connected to the upstream and downstream contact networks. , :
[0018]
[0019] in,
[0020]
[0021] In the formula, , The voltage of the anti-icing system connected to the upstream and downstream contact networks is obtained by sampling at the current time t. The output voltage of the anti-icing system is obtained by sampling at the current time t; The impedance per unit length of the overhead contact line. This refers to the length of the overhead contact line;
[0022] Calculate the sum of the current contact network voltage differences. :
[0023]
[0024] In the formula, The amplitude of the reference voltage. , They are respectively , The amplitude;
[0025] S1.4, as Then let , Proceed to the next step; otherwise, proceed to the next step.
[0026] S1.5, let , Return to S1.2;
[0027] S2, based on the optimal phase angle To obtain the reference value for anti-icing current or de-icing current:
[0028]
[0029] In the formula, To prevent the de-icing system from being connected to the voltage phase of the upstream contact network.
[0030] Furthermore, this also includes: monitoring the voltage of the overhead contact line. ,like or Then, S1 and S2 are executed again, and the initial value of the anti-icing current or de-icing current amplitude set in step S1.1 is reduced. ,until ; These are the minimum and maximum allowable voltage values for the overhead contact line, respectively.
[0031] The beneficial effects of this invention are as follows:
[0032] 1. Obtain power from another traction substation to avoid system power flow complexity caused by taking power from this traction substation.
[0033] 2. Using a single-phase PWM inverter allows for flexible control of the anti-icing current injected into the contact network, and also facilitates the optimization of the phase angle and amplitude of the anti-icing current in the contact network.
[0034] 3. While ensuring uninterrupted power supply and preventing ice melting in the overhead contact system, maintain the voltage of the overhead contact system within the allowable range for normal train operation to ensure normal train operation under extreme weather conditions such as ice, snow, and freezing rain. Attached Figure Description
[0035] Figure 1 Flowchart for preventing the de-icing system from entering working mode.
[0036] Figure 2 This is a topology diagram of the overhead contact line when the de-icing system is not in working mode.
[0037] Figure 3 Topology diagram of the contact network after the de-icing system enters working mode.
[0038] Figure 4 The control block diagram of the PWM inverter in the ice-melting system.
[0039] Figure 5 Equivalent circuit diagram for the operation of the de-icing system.
[0040] Figure 6 The flowchart for solving the optimal phase angle of the anti-icing current in anti-icing mode is shown.
[0041] Figure 7 The decision-making flowchart for outputting anti-icing current in anti-icing mode. Detailed Implementation
[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0043] This invention provides an uninterrupted power supply anti-icing system for AC contact networks and its control method, used for uninterrupted power supply anti-icing of AC contact networks in electrified railways. The AC contact network comprises multiple power supply sections. The power supply section requiring anti-icing draws power from the adjacent traction substation, and outputs anti-icing current after rectification and inversion. The inverter can be a PWM inverter with various topologies (including but not limited to two-level, three-level, cascaded H-bridge, and modular multi-level); the rectifier can be a diode uncontrolled rectifier to reduce system cost, or a PWM rectifier with various topologies (including but not limited to two-level, three-level, cascaded H-bridge, and modular multi-level) to ensure power quality. When the contact network remote video monitoring system detects that the line is already covered with ice, or the environmental parameter detection unit determines that there is a risk of icing based on actual parameters, the system operates in anti-icing or de-icing mode. It relies on the adjacent traction substation to supply power to the anti-icing system, obtains a stable DC voltage after rectification, then uses the inverter to output a controllable AC voltage, and finally provides anti-icing current to the contact network to be protected through a coupling transformer.
[0044] The aforementioned anti-icing system can achieve online anti-icing, meaning that the locomotive can operate normally during the anti-icing process. Therefore, the isolating switch at the location of the electrical phase separation needs to be opened, and at the same time, the up and down parallel switches of the zone need to be closed to form an anti-icing circuit while minimizing grid voltage fluctuations.
[0045] The control method of the above-mentioned anti-icing system determines whether to activate the AC anti-icing function based on the contact network environmental parameter monitoring unit and the contact network remote video monitoring system, specifically as follows:
[0046] 1) The overhead contact line environmental parameter monitoring unit includes a temperature sensor, a humidity sensor, and a wind speed sensor to monitor the temperature, humidity, and wind speed of the overhead contact line operating environment;
[0047] 2) The overhead contact line remote video monitoring system monitors whether there is icing on the overhead contact line. If there is icing and the icing intensity is greater than the allowable value, the anti-icing system enters the icing mode. If there is no icing, the parameters monitored by the environmental parameter detection unit are converted into specified signals and fed back to the data processing and control center. The data processing and control center combines meteorological parameters to determine whether the overhead contact line has reached the conditions for wet icing growth. If the conditions have not been met, the traction power supply system operates normally. If the conditions for wet icing growth are met, the control center issues a corresponding instruction, and the anti-icing system enters the anti-icing mode.
[0048] The specific implementation method is as follows:
[0049] like Figure 1 , Figure 2 and Figure 3 As shown, the process for the anti-icing system to enter working mode includes the following steps:
[0050] Step 1: First, initialize all circuit breakers and disconnect switches. The anti-icing system is temporarily not activated in anti-icing mode, allowing the traction power supply system to operate in normal mode. The specific switching operation process is as follows:
[0051] 1.1 Close the output feeder circuit breakers QF1 and QF2 of traction substation 1 and the feeder circuit breakers QF3 and QF4 of traction substation 2;
[0052] 1.2 Selectively close the upstream and downstream parallel switches QF8 and QF9 of the section to enable the upstream and downstream lines of the same power supply arm to operate in parallel and minimize the voltage fluctuation at the end of the grid.
[0053] Step 2: Start the overhead contact line environmental parameter monitoring unit.
[0054] Step 3: Determine if icing has occurred. The environmental parameter monitoring unit monitors the icing status of the overhead contact line, as well as ambient parameters such as temperature, humidity, and wind speed. If icing is detected on the overhead contact line and the icing intensity exceeds the allowable value, the system enters the de-icing mode. If no icing is detected on the overhead contact line, but the data processing and control system, combined with networked meteorological data, determines that the system has reached the conditions for wet icing growth (wind speed 3~15m / s, temperature -4~0°C, relative humidity >80%), the system enters the anti-icing mode. Otherwise, the traction power supply system continues to operate normally, and the monitoring unit continues to monitor external parameters. The switching operations in anti-icing mode and de-icing mode are the same; the difference is that the current required in de-icing mode is slightly higher than in anti-icing mode.
[0055] Step four, the system switches to AC anti-icing mode. Taking the right power supply arm of traction substation 1 as an example to achieve anti-icing, the specific process of the switching operation is as follows:
[0056] 4.1 The grid-connected circuit breaker QF7 and disconnector QS7 of the closed converter VSC1;
[0057] 4.2 Disconnect the parallel switch QF8 at the end of the contact network of traction substation 1;
[0058] 4.3 The grid-connected circuit breakers QF5 and QF6 and the disconnecting switches QS5 and QS6 of the closed converter VSC2;
[0059] 4.4 The feeder circuit breakers and disconnect switches of traction substations 1 and 2 remain closed, and the up and down contact networks of traction substation 1 and converter VSC2 form a closed anti-icing circuit.
[0060] 4.5 Start the data processing and control system, and adjust the de-icing and anti-icing current output by the system according to the icing status of the line and environmental parameters.
[0061] Figure 2The diagram shown illustrates the traction power supply system operating in normal mode.
[0062] Figure 2 During this period, the anti-icing system is not in use, the up and down parallel switches of the combined substation are closed, and traction substations 1 and 2 are supplying power to the up and down lines normally.
[0063] Figure 3 The diagram shown is a schematic of the anti-icing system operating in AC anti-icing mode.
[0064] Figure 3 In the process, the traction substation adjacent to the circuit to be de-iced provides voltage to the converter. After rectification, the voltage is inverted by the inverter to obtain the required single-phase AC voltage. Finally, the voltage is injected into the end of the contact network to be de-iced through the coupling transformer, which serves as the de-icing power supply to provide de-icing current for the line.
[0065] Figure 4 The diagram shown is a block diagram of a PWM inverter control.
[0066] The PWM inverter employs an AC current loop control strategy based on a quasi-proportional resonant (QPR) controller. It samples the inverter's output current, compares it with a calculated current reference value, and obtains the current difference. This difference is then used by the QPR controller to generate a PWM modulation signal. The initial reference value for the current amplitude is I... m The selection of the de-icing mode and the anti-icing mode differs. For example, given the conditions: ice thickness 8mm, ambient temperature -4℃, wind speed 6m / s, the critical de-icing current calculated using the corresponding formula is 616.47A, and the critical anti-icing current is 581.89A. To ensure the system's effectiveness, the de-icing mode can be set to I... m It is 650A, in anti-ice mode I m It is 600A.
[0067] For information on monitoring overhead contact line environmental parameters and calculating critical anti-icing and de-icing currents, please refer to the following literature:
[0068] [1] Ge Y, Chen J, Li Z, et al. Terminal Series-Connected Catenary Online Anti-Icing and De-Icing System for Double-Track AC Electric Railways[J]. IEEE Transactions on Industrial Electronics, 2025: 1-13.
[0069] [2] Zhou Tongxin. Research on anti-icing and de-icing schemes for overhead contact lines [D]. Southwest Jiaotong University, 2020.
[0070] like Figure 5 As shown, assuming the lengths of both the up and down contact networks are L, the impedance per unit length of the line is R+jX, and the output current of converter VSC2 is... Node 1 is the traction transformer connection node; nodes 2 and 3 are the converter VSC2 connection nodes at the end of the contact network. , Nodes 2 and 3 represent voltage; nodes 4 and 5 represent the locomotive access positions for the up and down lines during operation. Figure 5 In this circuit, both the up and down locomotives and the converter VSC2 are equivalent to controlled current sources. Taking the no-load state (i.e., no locomotives running on the line) as an example, the vector relationships between the voltages and currents in the equivalent circuit are as follows:
[0071]
[0072] The output voltage of the uninterruptible power supply anti-icing system for overhead contact lines is:
[0073]
[0074] Figure 6 The diagram shows the process of finding the optimal phase angle of the output anti-icing current under anti-icing mode. The positive direction is defined as the anti-icing current flowing into the upstream contact network and out of the downstream contact network, and the voltage phase at node 2 is used as the reference point. This is the reference phase.
[0075] For line load conditions (i.e., locomotive operation), an exhaustive loop method is used to find the optimal phase angle value of the output current, specifically:
[0076] 1) Sample the system output voltage at the current time t. and the voltage of nodes 2 and 3 of the contact wire , ;
[0077] 2) Calculate the theoretical value of the contact network end voltage at time t when the anti-icing device is not connected:
[0078]
[0079] 3) Enumerate and solve for the optimal phase angle of the anti-icing current that minimizes the change in grid voltage at nodes 2 and 3. Let the amplitude of the output current be I. m and initialize the output current phase angle. Minimum sum of voltage differences with the contact network Then determine whether to traverse 360 nodes (the phase angle corresponding to each node k). If the change is 1°, the loop ends; otherwise, proceed to the next step.
[0080] The anti-icing current at a certain cycle node was calculated:
[0081]
[0082] At this time, the voltage at nodes 2 and 3 of the contact wire is:
[0083]
[0084] The voltage amplitudes U2(k) and U3(k) at nodes 2 and 3 of the contact wire are obtained from the above formula, and their values are compared with the reference voltage U. S (U) S =27.5kV) The sum of the absolute values of the differences is:
[0085]
[0086] Furthermore, determine the calculated U f Is (k) less than If not, continue the loop; if yes, reassign the value. Continue executing the loop to the next node until all nodes have been traversed, and output the anti-icing current phase angle θ obtained from the loop. m .
[0087] Figure 7 The diagram shows the decision-making process for the output anti-icing current amplitude in anti-icing mode.
[0088] The data processing and analysis system dynamically updates the critical anti-icing current of the overhead contact line under the current environment based on environmental parameters and overhead contact line parameters, and sets an initial reference value I for the anti-icing current amplitude based on this. m Considering the relatively large critical anti-icing current calculated under actual environmental conditions, the initial reference value I of the current amplitude may be affected. m The current exceeds the allowable current carrying capacity of the overhead contact line; therefore, the anti-icing current amplitude needs to be limited to within the allowable current carrying capacity of the overhead contact line. Then, according to... Figure 6 The process shown calculates the optimal phase angle for the corresponding anti-icing current. Combined with the overhead contact line voltage limit conditions (U min =22.5kV, U max =29kV), continue to adjust the anti-icing current amplitude I output by the system. m From this, reference values for the current amplitude and phase angle are obtained, and further, reference values for the system output anti-icing current at each moment are obtained:
[0089]
[0090] Based on this, the anti-icing system adopts Figure 4 The control method shown accurately controls the terminal series converter to output the calculated anti-icing current reference value. .
[0091] Similarly, for the ice-melting mode, through Figure 6 , Figure 7 The process yields the corresponding ice-melting current phase angle and amplitude reference values, and controls the terminal series converter to accurately output the calculated ice-melting current reference value. .
[0092] The present invention relates to an AC contact network uninterrupted power supply and anti-icing system and its control method. The present invention can prevent ice melting by keeping the contact network uninterrupted, while maintaining the contact network voltage within the allowable range for normal train operation, thus ensuring the normal operation of the train under extreme weather conditions such as ice, snow and freezing rain.
Claims
1. An AC catenary continuous power anti-icing system, characterized in that, It includes a rectifier and a PWM inverter connected in sequence; the output terminal of the PWM inverter is connected to the primary of a second transformer; one end of the secondary of the second transformer is connected to the anti-icing upstream contact network through a second disconnecting switch and a second circuit breaker, and the other end is connected to the anti-icing downstream contact network through a third disconnecting switch and a third circuit breaker, wherein the anti-icing upstream and downstream contact networks are powered by a first traction substation; the input terminal of the rectifier is connected to the secondary of the first transformer; One end of the primary winding of the first transformer is connected to the upstream or downstream contact network supplied by the second traction substation via the first disconnecting switch and the first circuit breaker, while the other end is grounded.
2. The anti-icing system of claim 1, wherein, The second traction substation is adjacent to the first traction substation.
3. The control method of the anti-icing system according to claim 1, characterized by, When the upstream and / or downstream contact networks of the anti-icing system meet the anti-icing or de-icing conditions, the parallel switches of the upstream and downstream contact networks are disconnected, and the first isolating switch, the first circuit breaker, the second isolating switch, the second circuit breaker, the third isolating switch, and the third circuit breaker are closed, so that the anti-icing system enters the anti-icing mode or the de-icing mode; the output current of the PWM inverter is sampled, and the current difference is calculated with the anti-icing current reference value or the de-icing current reference value. A PWM modulation signal is generated through quasi-proportional resonance control to control the PWM inverter.
4. The control method for the anti-icing system as described in claim 3, characterized in that, The reference value for anti-icing current or de-icing current is set according to the critical anti-icing current or critical de-icing current, and is less than or equal to the allowable current carrying capacity of the contact network.
5. The control method of the anti-icing system according to claim 3, characterized by, The anti-icing current reference value or de-icing current reference value is obtained by the following method: S1. The optimal phase angle of the anti-icing current or de-icing current is obtained by enumeration. ,include: S1.1 Set the initial value of the anti-icing current or de-icing current amplitude according to the critical anti-icing current or critical de-icing current. , Less than or equal to the allowable current carrying capacity of the overhead contact line; phase angle of the initial anti-icing current or de-icing current. Set the minimum value of the sum of the contact network voltage differences. ;make ; S1.2, if then continue; otherwise, the current phase angle is the optimal phase angle; S1.3 Calculate the anti-icing current or de-icing current: ； calculating the output voltage of the de-icing system connected to the overhead catenary system, the down conductor , : in, In the formula, , The voltage of the anti-icing system connected to the upstream and downstream contact networks is obtained by sampling at the current time t. The output voltage of the anti-icing system is obtained by sampling at the current time t; The impedance per unit length of the overhead contact line. This refers to the length of the overhead contact line; calculating the sum of the current catenary voltage differences : wherein is the amplitude of the reference voltage, , are respectively , the amplitude of the reference voltage. S1.4, if then let , , perform next step; else, perform next step; S1.5, let , , return to S1.2; S2, according to the best phase angle , to obtain the anti-icing current reference value or the de-icing current reference value: In the formula, The voltage phase to which the de-icing system is connected to the overhead contact line.
6. The control method of the anti-icing system according to claim 5, characterized by, Also includes: Monitoring the voltage of a catenary If or then the steps S1, S2 are re-executed and the initial value of the anti-icing or de-icing current amplitude set in said step S1.1 is reduced until ; are respectively the minimum and maximum values of the catenary voltage allowed.