A setting method of a human body tolerance satisfying rail potential limiting device

Abstract

The application provides a setting method of a rail potential limiting device meeting human body tolerance, comprising the following steps: S1: obtaining a human body tolerance limit voltage and a corresponding time table; S2: adjusting the voltage value of the tolerance limit voltage corresponding to each tolerance time in the table of step S1 to obtain a delay time and voltage setting value corresponding table; S3: adjusting the table obtained in step S2 according to the contactor action time without delay, the step length and the setting value range of the thyristor trigger voltage to obtain a final delay time and voltage setting upper limit value corresponding table of the rail potential limiting device. The application uses the disclosed and recognized human body tolerance limit voltage and the corresponding time provided in the standard, combines the current equipment technical level, comprehensively considers the action logic process, the setting value setting range and the step length, the inherent time of the equipment and other factors, and proposes the setting voltage setting value and the time setting value upper limit meeting the human body tolerance limit, which is used for setting multiple groups of setting values.

Description

Technical Field

[0001] This invention belongs to the field of protection for DC traction power supply systems in urban rail transit, and specifically relates to a setting method for a rail potential limiting device that meets human tolerance. Background Technology

[0002] In urban rail transit traction power supply systems that use steel rails as the negative return path, a rail potential limiting device is installed between the insulated rails and the ground to ensure passenger safety. When the rail potential exceeds a set value, the rail potential limiting device closes, clamping the rail potential to the ground potential. When the current between the rail and ground falls below the set value and the voltage recovers, the rail potential limiting device automatically resets, disconnecting the rail from the ground and cutting off the stray current leakage path. By closing and opening the rail potential limiting device according to the system operating conditions, the stray current protection system is not compromised while ensuring passenger safety.

[0003] In recent years, abnormal rail potential, frequent rail potential activation, or even direct locking have become common issues on operating subway lines. This is particularly pronounced during locomotive startup, with abnormal rail potential activation often occurring within the 120V-150V range. In some cases, this has even led to the prolonged closure of rail potential limiting devices, resulting in persistently grounded rail operation and persistently high stray currents. The high rail potential is caused by a combination of factors, and a definitive and complete solution has yet to be found.

[0004] To ensure personal safety, the setting value of rail potential limiting devices should be closely matched with the human body's tolerance limit voltage, operating within that range. The current human tolerance limit is specified in IEC 62128-2013 "Railway installations—Fixed installations—Electrical safety, grounding and circuitry—Part 1: Protection against electric shock" section 9.3.2.2. The human tolerance limit voltage and corresponding time are shown in Table 1.

[0005] Table 1: Human Body's Tolerance Limit Voltage and Corresponding Time Table

[0006]

[0007]

[0008] In existing urban rail transit power supply systems, rail potential limiting devices mostly employ a thyristor and contactor combination. According to the control logic, after the voltage between the rail and ground reaches the corresponding set voltage value, the contactor and thyristor close after a delay or instantaneously without delay. The voltage setpoint V of the rail potential limiting device consists of two sets of voltage setpoints, V1 and V2, corresponding to different delay times, set by the contactor, and a trigger voltage setpoint V3 for the thyristor. Since the delay times t2 and t3 of the voltage setpoints V2 and V3 in the operating logic correspond to the inherent operating times of the contactor and thyristor, respectively, or in other words, the setpoints for both delay times are 0, the actual time setpoint is only the delay time t1 of the set voltage setpoint V1.

[0009] The current setting curve and corresponding action curve of the rail potential limiting device in the urban rail transit power supply system (the contactor action time without delay is considered to be 0.15s) and the human tolerance curve are as follows: Figure 1 As shown in the diagram. The solid line represents the human tolerance curve, the dashed line represents the rail potential limiting device actuation curve, and the dotted line represents the rail potential limiting device setting curve. The shaded area is located above the rail potential limiting device actuation curve and below the human tolerance curve, corresponding to the rail potential actuation zone that meets human tolerance requirements to ensure personal safety. This zone is relatively large, especially in the long-term withstand voltage range of 120V-150V. When the actuation zone margin of the rail potential limiting device is too large, appropriately increasing the setting value and reducing the actuation zone, while not fundamentally solving the problem of frequent actuation, can obviously improve and alleviate the situation to a great extent. The grid shaded area in the diagram represents the danger zone where the actuation exceeds human tolerance, posing a threat to personal safety. Summary of the Invention

[0010] This invention addresses the technical problems existing in the prior art by proposing a setting method for a rail potential limiting device that meets human tolerance. Utilizing the publicly recognized human tolerance limit voltage and corresponding time provided in the standard, and considering factors such as the current technical level of the equipment, the action logic process, the setting range and step size, and the inherent time of the equipment, this invention proposes a setting voltage setting value and a time setting upper limit that meet the human tolerance limit, which can be used to set multiple sets of values.

[0011] The technical solution adopted in this invention is: a method for setting a rail potential limiting device that meets human tolerance, comprising the following steps:

[0012] S1: Obtain the human body's tolerance limit voltage and the corresponding time schedule;

[0013] S2: Lower the voltage value of the withstand limit voltage corresponding to each withstand time in the table of step S1; obtain the table of correspondence between delay time and voltage setting value;

[0014] S3: Adjust the table obtained in step S2 according to the contactor action time without delay, the step size of the thyristor trigger voltage and the set value range to obtain the final table corresponding to the delay time and the upper limit value of the voltage setting of the rail potential limiting device.

[0015] Furthermore, in step S2, the voltage value is lowered by two bits.

[0016] Furthermore, step S3 includes the following steps:

[0017] S3.1: The time setting value for the delay time being lower than the contactor operating time tj without delay is completed by the fast-acting thyristor; select the maximum delay time tm from the table obtained in step S2 that is lower than the contactor operating time tj without delay, and the voltage setting value Vm+2 corresponding to the delay time tm.

[0018] S3.2: Based on the step size and set value range of the thyristor trigger voltage, determine the maximum thyristor trigger voltage VG below the voltage setting value Vm+2. The thyristor trigger voltage VG and the inherent action time of the thyristor are used as a set of delay times and voltage setting upper limit values ​​for the rail potential limiting device.

[0019] S3.3: Delete the voltage setting values ​​in the table obtained in step S2 that are greater than the thyristor trigger voltage VG and their corresponding delay times; subtract the contactor action time tj without delay from the remaining delay times and use it as the delay time of the rail potential limiting device; use the voltage setting values ​​corresponding to the remaining delay times as the upper limit of the voltage setting of the rail potential limiting device.

[0020] S3.4: Based on the delay time and voltage setting upper limit value of the rail potential limiting device obtained in steps S3.2 and S3.3, the corresponding table of delay time and voltage setting upper limit value of the rail potential limiting device is finally obtained.

[0021] Furthermore, in step S1, referring to the minimum step size of the human body's tolerance limit voltage as 5V, within the tolerance time range of 300s corresponding to the tolerance limit voltage of 150V, five voltage values ​​less than 150V are inserted, namely 145V, 140V, 135V, 130V and 125V. The tolerance time corresponding to the inserted voltage values ​​is 300s, while the tolerance time corresponding to the tolerance limit voltage of 150V is adjusted to 1.1s.

[0022] Furthermore, in step S3.3, the delay time of the rail potential limiting device with a value greater than or equal to 300-tj is adjusted so that its value gradually increases. The adjusted delay time of the rail potential limiting device is between (1.2-tj) and (300-tj).

[0023] Furthermore, in step S3.3, the delay times of the adjusted rail potential limiting device are 1.5s, 120s, 180s and 240s, respectively.

[0024] Compared with the prior art, the beneficial effects of this invention are:

[0025] 1. This invention is strictly tuned according to human tolerance, ensuring personal safety and avoiding the occurrence of dangerous areas.

[0026] 2. The multi-segment setting of this invention more accurately fits the human tolerance curve and effectively reduces unnecessary protective action zones.

[0027] 3. Without increasing investment, this invention largely solves the problem of frequent rail voltage fluctuations by adjusting the setpoint, especially between 120V and 150V during locomotive startup. Attached Figure Description

[0028] Figure 1 This is a graph showing the human tolerance curve and the current rail potential limiting device's action and setting curves in existing technologies.

[0029] Figure 2 This is a flowchart of an embodiment of the present invention;

[0030] Figure 3 The diagram shows the human tolerance curve and the upper limit curve of the rail potential limiting device's operation and setting limit curve, respectively, according to an embodiment of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiments of the present invention provide a method for setting a rail potential limiting device that meets human tolerance, such as... Figure 2 As shown, it includes the following steps:

[0033] S1: Obtain the human body's tolerance limit voltage and the corresponding time schedule, as shown in Table 1.

[0034] Referring to the minimum step size of the human body's tolerance limit voltage as 5V, within the tolerance time range of 300s corresponding to the tolerance limit voltage of 150V, five voltage values ​​less than 150V are inserted, namely 145V, 140V, 135V, 130V and 125V. The tolerance time corresponding to the inserted voltage values ​​is 300s, while the tolerance time corresponding to the tolerance limit voltage of 150V is adjusted to 1.1s, as shown in Table 2.

[0035] Table 2 shows the human body's tolerance limit voltage and corresponding time schedule for tuning.

[0036]

[0037] The voltage value inserted corresponds to the 120V-150V range where frequent operation occurs. Increasing the reference value within this range allows for a better reduction of the voltage value in step S2, enabling targeted improvement of the operating range.

[0038] S2: Lower the withstand limit voltage value corresponding to each withstand time in Table 2; the voltage value is lowered by two positions, that is, the voltage value in Table 2 is shifted two positions to the left. When the voltage value is lowered, withstand voltages V1 and V2 are removed from Table 2, withstand times t18 and t19 are deleted from Table 2 since there are no corresponding withstand voltages, and t17, since it corresponds to 120V, still has a withstand time of >300s. The corresponding table of delay time and voltage setting value is obtained, as shown in Table 3.

[0039] Table 3. Delay time and voltage setting value corresponding to the upper limit of the rail potential limiting device's operation (broken line).

[0040]

[0041] S3: Adjust Table 3 according to the contactor action time without delay, the step size of the thyristor trigger voltage and the set value range to obtain the final table of the correspondence between the delay time and the upper limit value of the voltage setting of the rail potential limiting device.

[0042] The specific steps are as follows:

[0043] When the operating time of the no-delay contactor is tj = 0.15s, and the thyristor trigger voltage range is 400V-600V (in 50V steps):

[0044] S3.1: The time setting value for a delay time lower than the contactor operating time tj without delay is completed by a fast-acting thyristor; select the maximum delay time t3 lower than the contactor operating time tj without delay from Table 3, that is, select the maximum delay time tm = t3 = 0.1s lower than 0.15s from Table 3. The voltage setting value corresponding to the delay time t3 is V5, V5 = 460V.

[0045] S3.2: Based on the step size and setpoint range of the thyristor trigger voltage, determine the maximum thyristor trigger voltage VG = 450V below the voltage setting value V5. The thyristor trigger voltage VG and the thyristor's inherent operating time (0.0001s) are used as the highest setpoints for the delay time and voltage setting upper limit of the rail potential limiting device, i.e., T0 = 0.0001s, U0 = 450V.

[0046] S3.3: Delete the voltage setting values ​​V3-V5 that are greater than the thyristor trigger voltage VG and their corresponding delay times t1-t3 in Table 3.

[0047] The remaining delay times t4-t17 in Table 3 have a delay time of 300s or more from t14 to t17. This is very advantageous for delay time tuning, allowing for selection of multiple possible values ​​within a wide tuning range, rather than being limited to the baseline values ​​in the table. Therefore, the delay time t4-t17 is divided into two parts, t4-t13 and t14-t17, for adjustment.

[0048] The delay time t4-t13 in Table 3, minus the contactor action time tj without delay, is taken as the delay time T1-T10 of the rail potential limiting device; the voltage setting value corresponding to the delay time t4-t13 is taken as the upper limit value U1-U10 of the voltage setting of the rail potential limiting device.

[0049] The values ​​of delay times t14-t17 in Table 3 are reduced, and the adjusted delay times of the rail potential limiting device range from (1.2-tj) to (300-tj), with the corresponding values ​​gradually increasing. The delay times t14-t17 can be adjusted to delay times T11 = 1.5s, T12 = 120s, T13 = 180s, and T14 = 240s, respectively. The voltage setting values ​​corresponding to the delay times t14-t17 are used as the upper limit values ​​U11-U14 of the voltage setting for the rail potential limiting device.

[0050] The final table showing the correspondence between the delay time and the upper limit of the voltage setting of the rail potential limiting device is shown in Table 4.

[0051] Table 4: Delay Time and Upper Limit Value of Voltage Setting for Rail Potential Limiting Device

[0052]

[0053]

[0054] Based on the data in Table 1-4, the following graphs were obtained: human tolerance curve, upper limit of rail potential limiting device operation curve, and upper limit of setting curve. Figure 3 As shown, the human-tolerant action zone (I) is indicated by the diagonal shading, the human-tolerant action zone (II) by the star-shaped shading, and the human-tolerant action zone (III) by the mesh-like shading. The human-tolerant action zone (I) is the upper limit of the setting; the human-tolerant action zone (II) still has room for compression; the human-tolerant action zone (III) is the human-tolerant action zone increased due to the rapid closing of the thyristor.

[0055] 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 designed by those skilled in the art under the inspiration of the technical solutions of the present invention, within the substance and protection scope of the present invention, to achieve the above-mentioned technical effects, or any equivalent changes and improvements made to the scope of the application, should still fall within the patent protection scope of the present invention.

Claims

1. A method for setting a rail potential limiting device that meets human tolerance, characterized in that: Includes the following steps: S1: Obtain the human body's tolerance limit voltage and the corresponding time schedule; S2: Lower the voltage value of the withstand limit voltage corresponding to each withstand time in the table of step S1; obtain the table of correspondence between delay time and voltage setting value; S3: Adjust the table obtained in step S2 according to the contactor action time without delay, the step size of the thyristor trigger voltage and the set value range to obtain the final table corresponding to the delay time and the upper limit value of the voltage setting of the rail potential limiting device. Step S3 includes the following steps: S3.1: The time setting value for the delay time being lower than the contactor action time tj without delay is completed by the fast-acting thyristor; select the maximum delay time tm from the table obtained in step S2 that is lower than the contactor action time tj without delay, and the voltage setting value Vm+2 corresponding to the delay time tm. S3.2: Based on the step size and set value range of the thyristor trigger voltage, determine the maximum thyristor trigger voltage VG below the voltage setting value Vm+2. The thyristor trigger voltage VG and the inherent action time of the thyristor are used as a set of delay times and voltage setting upper limit values ​​for the rail potential limiting device. S3.3: Delete the voltage setting values ​​in the table obtained in step S2 that are greater than the thyristor trigger voltage VG and their corresponding delay times; subtract the contactor action time tj without delay from the remaining delay times and use it as the delay time of the rail potential limiting device; use the voltage setting values ​​corresponding to the remaining delay times as the upper limit of the voltage setting of the rail potential limiting device. S3.4: Based on the delay time and voltage setting upper limit value of the rail potential limiting device obtained in steps S3.2 and S3.3, the corresponding table of delay time and voltage setting upper limit value of the rail potential limiting device is finally obtained.

2. The setting method for the rail potential limiting device that meets human tolerance as described in claim 1, characterized in that: In step S2, the voltage value is lowered by two bits.

3. The setting method for the rail potential limiting device that meets human tolerance as described in claim 1, characterized in that: In step S1, referring to the minimum step size of the human body's tolerance limit voltage as 5V, within the tolerance time of 300s corresponding to the tolerance limit voltage of 150V, five voltage values ​​less than 150V are inserted, namely 145V, 140V, 135V, 130V and 125V. The tolerance time corresponding to the inserted voltage values ​​is 300s, while the tolerance time corresponding to the tolerance limit voltage of 150V is adjusted to 1.1s.

4. The setting method for the rail potential limiting device that meets human tolerance as described in claim 3, characterized in that: In step S3.3, the delay time of the rail potential limiting device with a value greater than or equal to 300-tj is adjusted so that its value gradually increases. The value of the delay time of the rail potential limiting device after adjustment is between (1.2-tj) and (300-tj).

5. The setting method for the rail potential limiting device that meets human tolerance as described in claim 4, characterized in that: In step S3.3, the delay times of the adjusted rail potential limiting device are 1.5s, 120s, 180s and 240s respectively.

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