Disconnection protection method for electrified highway overhead line system

Abstract

The invention discloses a disconnection protection method for an electrified highway contact network, and belongs to the field of electrified highway direct current power supply system protection. A displacement sensor, a speed sensor and an acceleration sensor are installed on a balance weight of an anchoring compensation device, and an angular acceleration sensor is installed on a ratchet wheel when the anchoring compensation device is in a ratchet wheel type; a broken line judgment device is locally installed near the lower anchor column and used for monitoring real-time data of all the sensors and judging whether the contact network is broken or not according to the received real-time data, and a broken line tripping instruction is sent out if it is judged that a broken line fault occurs; and after a microcomputer protection measurement and control unit of the traction station for supplying power to the power supply subarea where the broken line fault occurs receives a broken line tripping instruction sent by the broken line judgment device, a feeder circuit breaker of the traction station is controlled to trip so as to isolate the power supply subarea where the broken line occurs. According to the technical scheme, operation safety can be remarkably improved, inspection resources are saved, and safety risks are reduced.

Description

Technical Field

[0001] This invention relates to the field of protection for DC power supply systems of electrified highways, and in particular to a method for protecting the contact wire of electrified highways from breakage. Background Technology

[0002] Electrified highways refer to roads equipped with electric traction power supply systems along their routes, enabling motor vehicles to continuously draw power from the traction network during operation. This provides uninterrupted power to vehicles in motion and represents a new mode of rail transit. In traditional urban rail transit and trunk railways where locomotives provide continuous power, a contact network is installed along the line as the positive terminal, and the running rail or dedicated return rail serves as the negative terminal. When a contact network failure occurs, it typically sags and connects to the running rail or a metal grounding electrode, creating a short circuit between the positive and negative terminals. The resulting large short-circuit current triggers current protection, causing the corresponding circuit breaker in the substation to trip. Even if the contact network failure does not connect to the running rail and no abnormal short-circuit current is generated, urban rail transit or trunk railways, being closed and independent right-of-way, will not pose a danger to the public.

[0003] For electrified highways, apart from the overhead contact line as the positive pole, no metal conductors are installed on the ground as the negative pole for return current. Instead, the same overhead contact line is installed as the negative pole for return current. When the overhead contact line breaks, there is no possibility of the positive or negative contact line connecting to the ground metal conductor to form a short circuit current. Conventional current protection fails, so the corresponding circuit breaker in the substation will not trip. At the same time, electrified highways do not have independent right-of-way. A broken overhead contact line while energized can easily cause personal injury and property damage to passing vehicles or people, which contradicts the original intention of safe and efficient transportation.

[0004] Therefore, there is an urgent need for a method to protect the overhead contact line of electrified highways from disconnection, which can solve the difficulties in applying existing technologies, significantly improve operational safety, save inspection resources, and reduce safety risks. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for protecting the contact wires of electrified highways from wire breakage, thereby improving operational safety, saving inspection resources, and reducing safety risks.

[0006] This invention achieves this objective through the following technical solution: A method for protecting the overhead contact line from breakage in electrified highways includes the following: Displacement sensors, velocity sensors, and acceleration sensors are installed on the weights of the anchor compensation device. When the anchor compensation device is ratchet type, an angular acceleration sensor also needs to be installed at the ratchet. A wire breakage detection device is installed on-site near the lower anchor post to monitor the real-time data of each sensor and determine whether the contact network has broken based on the received real-time data. After the logic detects a wire breakage fault, a wire breakage trip command is issued. After receiving the trip command from the line breakage detection device, the microcomputer protection and control unit in the traction substation that supplies power to the power supply zone where the line breakage occurred controls the feeder circuit breaker switch of the traction substation to trip in order to isolate the power supply zone where the line breakage occurred.

[0007] Furthermore, the wire breakage detection device determines whether the overhead contact line is broken based on the following: Condition 1: The real-time acceleration a1 of the weight on the ground is vertically upward and its value is greater than the set value A. js And the duration exceeds the set time T dz ; Condition 2: Calculate the real-time acceleration of the weight relative to the ground by differentiating the real-time velocity V of the weight relative to the ground. The acceleration a2 is vertically upward and its value is greater than the set value A. js And the duration exceeds the set time T dz ; Condition 3: Obtain the real-time acceleration of the weight on the ground by taking the multiple differential of the real-time displacement S of the weight above the ground. When the acceleration a3 is vertically upward and its value is greater than the set value A js And the duration exceeds the set time T dz ; Condition 4: Utilize the real-time angular acceleration a of the ratchet. ω The real-time linear acceleration, i.e., the acceleration of the weight on the ground, is calculated. Where R is the ratchet radius, and when the acceleration a4 is vertically upward and its value is greater than the set value A. js And the duration exceeds the set time T dz ; For ratchet installation, if at least one of conditions 2 and 3 and conditions 1 and 4 are met simultaneously, or for pulley installation, if at least one of conditions 2 and 3 and condition 1 are met simultaneously, the contact wire is determined to be disconnected, and the disconnection judgment device issues a disconnection trip command; otherwise, the disconnection judgment procedure of the disconnection judgment device resets.

[0008] Furthermore, A js The set range is 25≤A js ≤75m / s 2 .

[0009] Furthermore, T dz Set as 10≤T dz ≤27ms.

[0010] Furthermore, when determining whether conditions 1 to 4 are satisfied, the recording duration T is... dz During the process, when the measured or calculated acceleration is less than the set value A js Duration T f If so, the condition determination procedure will revert.

[0011] Furthermore, T f The set range is 0 < T f ≤5ms.

[0012] Furthermore, the disconnection detection device is connected to each sensor via a dual wireless communication network.

[0013] Furthermore, the disconnection detection devices are connected via a GOOSE network.

[0014] Compared with the prior art, the beneficial effects of this invention are as follows: 1) This invention enables power outage of the corresponding power supply section after the contact wire breaks, greatly improving the safety of the system.

[0015] 2) This invention has no impact on overhead contact lines and vehicles, and poses no safety risks.

[0016] 3) This invention enables the location of broken anchor sections in the overhead contact line, thereby improving the speed of fault location. Attached Figure Description

[0017] Figure 1 This is a diagram showing the state of the weight and ratchet before the catenary cable breaks according to the present invention. Figure 2 This is a diagram showing the state of the weight and ratchet after the load-bearing cable breaks according to the present invention. Figure 3 This is a schematic diagram of the fault detection scheme for the overhead contact line of an electrified highway to which this invention is applicable. Figure 4 This is a schematic diagram showing the installation positions of each sensor in this invention; Figure 5 This is a diagram showing the displacement curve during the wire breakage process of the present invention. Figure 6 This is a graph showing the speed curve changes during the wire breakage process of the present invention; Figure 7 This is a graph showing the acceleration curve changes during the wire breakage process of the present invention. Detailed Implementation

[0018] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] See Figures 1 to 7 This invention discloses a method for protecting the overhead contact line of an electrified highway from wire breakage. The method involves installing a displacement sensor, a velocity sensor, and an acceleration sensor on the weight of a lower anchor compensation device. When the lower anchor compensation device is ratchet-type, an angular acceleration sensor is installed on the ratchet. A wire breakage detection device is installed locally near the lower anchor post to monitor the real-time data from each sensor and determine whether a wire breakage has occurred based on the received data. After logically identifying a wire breakage fault, a wire breakage trip command is issued. The microcomputer protection and control unit within the traction substation supplying power to the affected power supply section receives the wire breakage trip command from the detection device and controls the power supply feeder circuit breaker switch of the traction substation to disconnect, thus isolating the affected power supply section.

[0020] The corresponding sensor installation locations are as follows: Figure 4 As shown, the collected displacement, velocity, acceleration, and angular acceleration information are aggregated through a dual wireless communication network to a locally installed wire breakage detection device. The wire breakage detection device processes the data, performs calculations and analyses, and makes logical judgments to determine that a wire breakage fault has occurred.

[0021] Figure 3 The dashed line connection between the interrupted line detection device and the microprocessor-based protection and control unit of the traction substation only indicates the correspondence for issuing trip commands; the actual connection method uses a GOOSE network. After receiving the interrupted line trip command from the interrupted line detection device, the microprocessor-based protection and control unit controls the feeder circuit breaker switch of the traction substation to trip, thereby isolating the power supply zone where the interrupted line occurred.

[0022] In the DC traction power supply system of electrified highways, the contact wire and catenary are connected by droppers spaced 3m to 8m apart, anchored to lower anchor posts spaced 40m to 60m apart within each power supply zone. Tension is applied to the contact wire by the weight of a weight at the lower anchor post. When a contact wire or catenary breaks, the weight will suddenly fall, almost like a free fall, and the ratchet (or pulley) mounted on the upper end of the lower anchor post will suddenly rotate due to the loss of tension. Therefore, this invention concludes that a contact wire (contact wire or catenary) has broken by judging the sudden fall of the weight and the sudden rotation of the ratchet (or pulley), and by observing a significant change in the mechanical physical parameter acceleration α during this abrupt change.

[0023] A detailed analysis of the changes in movement of the weights and ratchet (or pulley) in the overhead contact system when a contact wire or catenary cable breaks: At the instant the line breaks, the initial acceleration 'a' is slightly less than 'g' and is directed downwards.

[0024] At the instant the contact wire or catenary cable breaks, the upward tension of the weight instantly decreases to zero, and the upward force is only the maximum static friction force f. m At this moment, the cooperative force acting on the weight is f m Much smaller than mg, therefore F at this time ∑ The direction is downward, and the position of the weight at this moment is marked as the origin O, with time 0. At this moment, the initial acceleration a0 of the weight at point O is slightly less than g, and the direction is downward.

[0025] The initial velocity V0 = 0.

[0026] At the same time, although the ratchet (or pulley) does not rotate, it also has an initial angular acceleration a. ω0 The direction is from the outside of the lower anchor post towards the lower anchor post.

[0027] In the initial stage of the first descent, the acceleration 'a' is constant and slightly less than 'g', and its direction is downward.

[0028] Due to the downward acceleration *a*, the weight begins to fall with an acceleration *a* slightly less than *g*. During the fall, the upward static friction force *f* on the weight... m The contact wire or catenary cable disappears, replaced by the sliding friction force f between the contact wire or catenary cable and the ratchet (or pulley). h The resistance f between the weight and the air z The forces acting upwards (after being redirected by a ratchet or pulley, they act directly on the weight) are the combined forces acting on the weight during this stage. f h、 f z All are much smaller than mg, therefore F at this time ∑The direction remains downwards. During this stage, the acceleration 'a' of the falling weight remains essentially constant, its magnitude is slightly less than 'g', and its direction is downwards.

[0029] The velocity V increases with uniform acceleration in the downward direction.

[0030] During this stage, the contact wire or catenary is not taut and is in a slack state.

[0031] The angular acceleration a of the ratchet (or pulley) ω The trend of change is the same as the trend of change of the acceleration 'a' of the falling weight.

[0032] During the middle stage of the first descent, the acceleration 'a' gradually decreases and its direction is downward.

[0033] As the weight falls downwards, the contact wire or catenary cable begins to be taut by the suspension wire (marked as position B at this moment, time t1), generating an upward tensile force f. l And gradually increase, the cooperative force acting on the weight during this stage is The direction remains downwards. During this stage, the acceleration 'a' of the falling weight gradually decreases, and its direction remains downwards.

[0034] The velocity V increases by decreasing acceleration a, and the direction is downward.

[0035] The angular acceleration a of the ratchet (or pulley) ω The trend of change is the same as the trend of change of the acceleration 'a' of the falling weight.

[0036] The acceleration inflection point during the first descent is when acceleration a decreases to 0 and velocity V reaches its maximum.

[0037] When the tensile force f l Increase to mg-f h -f z At that time, F ∑ =0, at this moment the acceleration a of the weight is 0. Mark the position of the weight at this moment as C, and the time as t2.

[0038] The velocity V reaches its maximum value and is directed downwards.

[0039] The angular acceleration a of the ratchet (or pulley) ω =0.

[0040] During the final stage of the first descent, the acceleration 'a' gradually increases and changes direction to upward.

[0041] As the weight continues to fall, the contact wire or catenary is subjected to an upward tensile force f from the suspension wire. l Rapidly increased, far greater than mg-f h -f z The cooperative force acting on the weight during this stage is The direction changes to upward. During this stage, the acceleration 'a' of the falling weight increases rapidly, far exceeding 'g', and its direction is upward.

[0042] The velocity V decreases sharply and is directed downwards.

[0043] The angular acceleration a of the ratchet (or pulley) ω The trend of change is the same as the trend of change of the acceleration 'a' of the falling weight.

[0044] At the lowest point of the first descent, the acceleration reaches its maximum, and the direction is upward.

[0045] When the velocity V drops to 0, the weight reaches the lowest point of the first descent. At this point, the upward tensile force f of the contact wire or catenary increases. l The maximum cooperative force acting on the weight. It also reaches its maximum, in the upward direction. Therefore, the acceleration 'a' of the weight reaches its maximum value, in the upward direction. Mark the position of the weight at this moment as A, and the time as t3.

[0046] The angular acceleration a of the ratchet (or pulley) ω Reach the maximum.

[0047] Thus, the process of the weight going from the moment the string broke to its first fall to the lowest point was completed.

[0048] The simulation curves of this process are as follows: Figures 5 to 7 As shown.

[0049] During this process, the velocity V starts from 0, accelerates to its maximum, and then rapidly decreases to 0; the acceleration a starts slightly less than g and moves downwards, passes through a constant region, quickly decreases to 0, then changes direction upwards and accelerates rapidly to its maximum value, which is much greater than g.

[0050] Therefore, by utilizing the abrupt change in the mechanical physical parameter of acceleration during the final stage of this process, the broken line can be determined as follows: Displacement, velocity, and acceleration sensors are installed in the middle of the sidewall of the weight to measure the displacement S of the weight above the ground, the velocity V of the weight relative to the ground, and the acceleration a of the weight relative to the ground, respectively. Displacement S, velocity V, and acceleration a are all positive in the vertically downward direction. When a ratchet is used at the anchor point of the contact wire (pulleys are too small to be installed), an angular acceleration sensor is installed in the gap between the ratchet spokes (the thickness of the device is less than the minimum operating clearance of the ratchet rope, so as not to affect the normal movement of the ratchet) to measure the rotational angular acceleration α of the ratchet. ω .

[0051] The judgment steps are as follows: The acceleration a1 of the weight relative to the ground is measured in real time, with the downward direction of a1 being positive. When the acceleration a1 is in the upward direction and its value is greater than the set value A... js The disconnection detection program starts when a1 is negative. And the duration exceeds T dz Condition 1 is satisfied.

[0052] The velocity V of the falling weight relative to the ground is measured in real time, with the downward vertical direction as positive. Differential calculations are then performed using the collected velocity V. The acceleration a2 of the weight relative to the ground can be calculated. When the acceleration a2 is upward and its value is greater than the set value A... js The disconnection detection program starts when a2 is negative. And the duration exceeds T dz Condition 2 is satisfied.

[0053] The displacement S of the weight above the ground is measured in real time, with the vertically downward direction of S being positive. The collected displacement S is then used to perform multiple differential calculations. The acceleration a3 of the weight relative to the ground can be calculated. When the acceleration a3 is upward and its value is greater than the set value A... js The disconnection detection program starts when a3 is negative. And the duration exceeds T dz Condition 3 is satisfied.

[0054] Real-time measurement of the ratchet's angular acceleration a ω Using the collected angular acceleration a ω Perform calculations This allows calculation of the linear acceleration of the ratchet, specifically the acceleration a4 of the weight relative to the ground, where R is the ratchet radius. When the acceleration a4 is upward and its value is greater than the set value A... js The disconnection detection program starts when a4 is negative. And the duration exceeds T dz Condition 4 is satisfied.

[0055] In any of the above conditions, during the recording duration T dz During the process, when the measured or calculated acceleration is less than the set value A js And exceeding T f When this condition is met, the disconnection detection program resets and waits for restart.

[0056] For ratchet installation, a wire breakage fault is determined to have occurred if conditions 1, 2, and 4 are met simultaneously, or conditions 1, 3, and 4 are met simultaneously, or conditions 1 to 4 are all met. For pulley installation, a wire breakage fault is determined to have occurred if conditions 1 and 2 are met simultaneously, or conditions 1 and 3 are met simultaneously, or conditions 1 to 3 are met simultaneously. If the conditions are not met, the wire breakage determination program resets and waits for restart.

[0057] The tuning ranges of the tuning parameters are shown in the table below:

[0058] When the weight is exposed to strong winds in an outdoor environment, it will cause violent up-and-down reciprocating oscillations. Although the amplitude of the up-and-down oscillations is close to the maximum displacement during a wire breakage fault, and the oscillation speed is also close to the maximum speed during a wire breakage fault, the oscillation acceleration is far different from the maximum acceleration during a wire breakage fault, and is far from reaching the protection level A. js Within the set value range, the line breakage protection will not be activated at all, and there is no possibility of malfunction.

[0059] Let the set value A js Take 50 m / s 2 T dz Take 10ms, T f Taking 2ms as an example, when the contact wire of the third anchor section in a certain power supply zone breaks, the simulation results are shown above, and the corresponding judgments are as follows: When the weight at the break point of the third anchor section falls, the acceleration sensor, velocity sensor, displacement sensor on the weight, and the angular velocity sensor on the ratchet (when a ratchet is used) all measure the corresponding values ​​in real time. The measured acceleration, velocity, and displacement correspond to the simulation curves mentioned above. All values ​​are transmitted via dual wireless channels to the break detection device installed nearby near the anchor column in this anchor section.

[0060] 0.25 seconds after the wire breakage, the acceleration value measured directly or indirectly by the angular velocity sensor on the wire breakage detection device (which uses an accelerometer, velocity sensor, displacement sensor, and angular velocity sensor on the ratchet (when a ratchet is used)) all exceeds 50 m / s². 2 If the direction is vertically upward, the contact wire breakage detection program in the device will be activated.

[0061] After 10ms (0.26s), the duration is exceeded, and conditions 1, 2, 3, and 4 are all satisfied. The disconnection detection device determines, based on logical judgment, that a disconnection fault has occurred in the contact network.

[0062] The microcomputer protection and control unit of the traction substation located at both ends of the power supply zone receives the information and trip command from the line break judgment device that the third anchor section in the power supply zone has experienced a line break fault. It executes the trip command, completes the line break protection, and cuts off the power supply to the power supply zone.

[0063] Based on the present invention, a method for protecting the contact network of electrified highways by means of the present invention can further encode the DC feeder circuit breakers, cross-zone switches and anchor sections in the power supply zone, and share the obtained and also encoded fault information by constructing a redundant GOOSE network. At the same time, combined with the status information of the relevant cross-zone switches, the corresponding DC feeder circuit breaker is tripped, and the faulty power supply zone is cleared.

[0064] The present invention has been described in detail above through embodiments, but the content described is only an exemplary embodiment of the present invention and should not be considered as limiting the scope of the present invention. The scope of protection of the present invention is defined by the claims. Any technical solutions designed by those skilled in the art using the technical solutions described in the present invention, or similar technical solutions designed by those skilled in the art under the inspiration of the technical solutions of the present invention, within the substance and scope of protection of the present invention, to achieve the above-mentioned technical effects, or equivalent changes and improvements made to the scope of the application, should still fall within the patent protection scope of the present invention. It should be noted that, for clarity, descriptions of some components and processes that are not directly and obviously related to the scope of protection of the present invention but are known to those skilled in the art have been omitted in the description of the present invention.

Claims

1. A method for protecting the contact wire of an electrified highway from wire breakage, characterized in that, Includes the following: Displacement sensors, velocity sensors, and acceleration sensors are installed on the weights of the anchor compensation device. When the anchor compensation device is ratchet type, an angular acceleration sensor also needs to be installed at the ratchet. A wire breakage detection device is installed on-site near the lower anchor post to monitor the real-time data of each sensor and determine whether the contact network has broken based on the received real-time data. After the logic detects a wire breakage fault, a wire breakage trip command is issued. After receiving the trip command from the line breakage detection device, the microcomputer protection and control unit in the traction substation that supplies power to the power supply zone where the line breakage occurred controls the feeder circuit breaker switch of the traction substation to trip in order to isolate the power supply zone where the line breakage occurred.

2. The method for protecting the contact wire of an electrified highway from wire breakage according to claim 1, characterized in that, The wire breakage detection device determines whether the overhead contact line is broken based on the following: Condition 1: The real-time acceleration a1 of the weight on the ground is vertically upward and its value is greater than the set value A. js And the duration exceeds the set time T dz ; Condition 2: Calculate the real-time acceleration of the weight relative to the ground by differentiating the real-time velocity V of the weight relative to the ground. The acceleration a2 is vertically upward and its value is greater than the set value A. js And the duration exceeds the set time T dz ; Condition 3: Obtain the real-time acceleration of the weight on the ground by taking the multiple differential of the real-time displacement S of the weight above the ground. When the acceleration a3 is vertically upward and its value is greater than the set value A js And the duration exceeds the set time T dz ; Condition 4: Utilize the real-time angular acceleration a of the ratchet. ω The real-time linear acceleration, i.e., the acceleration of the weight on the ground, is calculated. Where R is the ratchet radius, and when the acceleration a4 is vertically upward and its value is greater than the set value A. js And the duration exceeds the set time T dz ; For ratchet installation, if at least one of conditions 2 and 3 and conditions 1 and 4 are met simultaneously, or for pulley installation, if at least one of conditions 2 and 3 and condition 1 are met simultaneously, the contact wire is determined to be disconnected, and the disconnection judgment device issues a disconnection trip command; otherwise, the disconnection judgment procedure of the disconnection judgment device resets.

3. A method for protecting the contact wire of an electrified highway from wire breakage according to claim 2, characterized in that, A js The set range is 25≤A js ≤75m / s 2 .

4. A method for protecting the contact wire of an electrified highway from wire breakage according to claim 3, characterized in that, T dz Set as 10≤T dz ≤27ms.

5. A method for protecting the contact wire of an electrified highway from wire breakage according to claim 4, characterized in that, When determining whether conditions 1 to 4 are met, the recording duration T is... dz During the process, when the measured or calculated acceleration is less than the set value A js Duration T f If so, the condition determination procedure will revert.

6. A method for protecting the contact wire of an electrified highway from wire breakage according to claim 1, characterized in that, T f The set range is 0 < T f ≤5ms.

7. A method for protecting the contact wire of an electrified highway from wire breakage according to claim 1, characterized in that, The disconnection detection device is connected to each of the sensors via a dual wireless communication network.

8. A method for protecting the contact wire of an electrified highway from wire breakage according to claim 1, characterized in that, The disconnection detection devices are connected via a GOOSE network.

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