An overcurrent protection test method based on simulating the protection characteristics of thermal magnetic release

Abstract

The present invention relates to the technical field of ship power systems, and in particular to a power system overcurrent protection test method based on simulating the protection characteristics of a thermal-magnetic release. The present invention conducts power system overload and short-circuit protection tests by simulating the overcurrent protection characteristics of a thermal-magnetic release with an electronic release, which can verify the selectivity and effectiveness of the power system overcurrent protection design, making up for the deficiency of the prior art thermal-magnetic release that is unable to carry out overcurrent simulation tests, and avoiding arcing, ablation, etc. caused by the circuit breaker being interrupted by large current. The present invention provides an overcurrent protection simulation test method for a power system equipped with a thermal-magnetic release, which can accurately and efficiently verify the correctness of the system protection design.

Description

Technical Field

[0001] The present invention relates to the technical field of ship power systems, and in particular to a power system overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release. Background Art

[0002] Overcurrent faults in power systems are common. Improper system protection design can lead to a complete shipboard blackout or even more serious consequences. Therefore, before a power system is installed on a ship, it is typically tested to verify the selectivity and effectiveness of the system protection design. However, conducting high-current protection tests on power systems requires significant testing costs. Furthermore, circuit breakers can erode when interrupting high test currents. The larger the system's installed capacity, the greater the testing costs and potential hazards. Therefore, a simulation test method that does not require actual current flow is desirable.

[0003] Power systems typically use frame circuit breakers as protective devices for power supply networks, while thermal-magnetic molded case circuit breakers and electronic molded case circuit breakers are used for distribution network protection. Currently, both frame circuit breakers and electronic molded case circuit breakers are equipped with electronic releases, while thermal-magnetic molded case circuit breakers are equipped with thermal-magnetic releases. The main difference between electronic and thermal-magnetic releases in their tripping operation is that the electronic release outputs a trip signal to a magnetic flux converter, which then activates the tripping mechanism, while the thermal-magnetic release directly activates the tripping mechanism. This instantaneous operation can generate arcing, ablation, and other hazards. Given these differences, tripping can be determined simply by observing the magnetic flux converter in the electronic release, without requiring the tripping mechanism to operate. This means that electronic releases can be simulated to determine tripping operation without actually breaking the circuit. However, the tripping process of thermal-magnetic releases lacks intermediate steps, making simulation testing infeasible. At the same time, given that the electronic trip unit can flexibly adjust protection parameters within a certain range, it has the conditions to "imitate" the thermal-magnetic trip unit.

[0004] In view of the above situation, the present invention proposes a power system overcurrent protection test method based on simulating the protection characteristics of a thermal-magnetic release. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a power system overcurrent protection test method based on simulating the protection characteristics of a thermal-magnetic release, which can carry out power system overload protection tests by simulating the long-delay and instantaneous protection characteristics of a thermal-magnetic release through an electronic release, and verify the selectivity and effectiveness of the power system overcurrent protection design.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] An overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release mainly includes the following steps:

[0008] S1, select the electronic release for testing with the corresponding rated current according to the structure of the initial power supply and distribution branch to be tested in the power system;

[0009] S2, setting the protection parameters of the test electronic release based on the protection parameters of the thermal-magnetic release of the lower-level molded case circuit breaker in the initial power supply and distribution branch to be tested;

[0010] S3, replacing the thermal-magnetic release of the lower-level molded case circuit breaker in the initial power supply and distribution branch to be tested with the test electronic release, and then re-connecting it in series to the power supply and distribution branch to be tested to form a replaced power supply and distribution branch to be tested;

[0011] S4, select a suitable current generator or power supply device to generate the test current;

[0012] S5, carrying out an overload test and a short-circuit test on the replaced power supply and distribution branch to be tested.

[0013] Furthermore, the initial power supply and distribution branch to be tested includes a three-stage frame circuit breaker and a two-stage molded case circuit breaker, and the frame circuit breakers all use electronic releases. The upper molded case circuit breaker in the two-stage molded case circuit breaker uses an electronic release, and the lower molded case circuit breaker uses a thermal magnetic release.

[0014] Furthermore, in the replaced power supply and distribution branch to be tested, the lower-level molded case circuit breaker adopts the test electronic release, and the protection parameters of the test electronic release are set to be consistent with those of the thermal-magnetic release.

[0015] Furthermore, the protection parameters include long-delay protection parameters and instantaneous protection parameters.

[0016] Furthermore, whether the electronic release for testing is actuated is determined by collecting information on whether the electronic release for testing outputs a tripping signal.

[0017] Furthermore, when the electronic release for testing is actuated, its magnetic flux converter is actuated, and the output current during the actuation is read by the electronic release for testing, and a corresponding tripping signal is output.

[0018] Furthermore, the overload action time of the overload test is manually recorded using a stopwatch.

[0019] Furthermore, the test current is generated by a current generator, or by a power supply device of a test platform according to test conditions.

[0020] Compared with the prior art, the present invention has the following main advantages:

[0021] 1. The present invention uses an electronic release to simulate the overcurrent protection characteristics of a thermal-magnetic release to conduct power system overload and short-circuit protection tests. This can verify the selectivity and effectiveness of the power system overcurrent protection design, making up for the deficiency of the existing thermal-magnetic release in being unable to conduct overcurrent simulation tests, and avoiding arcing, ablation, etc. caused by the circuit breaker being interrupted by large currents.

[0022] 2. The present invention provides an overcurrent protection simulation test method for a power system equipped with a thermal-magnetic release, which can accurately and efficiently verify the correctness of the system protection design. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of typical power supply and distribution branch circuit breakers connected in series in an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of a power system protection simulation test based on simulating the protection characteristics of a thermal-magnetic release according to an embodiment of the present invention;

[0025] Figure 3 This is a comparison chart of protection curves of the electronic release 100E of the molded case circuit breaker simulating the characteristics of the thermal magnetic release 100P in an embodiment of the present invention;

[0026] Figure 4 This is a comparison chart of protection curves of the electronic release 200E of the molded case circuit breaker simulating the characteristics of the thermal magnetic release 200P in an embodiment of the present invention;

[0027] Figure 5 This is a five-level power supply and distribution branch selective protection curve with a 200A thermal-magnetic molded case circuit breaker at the end in an embodiment of the present invention;

[0028] Figure 6 This is a selective protection curve for a five-level power supply and distribution branch circuit with a 100A thermal-magnetic molded case circuit breaker at the end in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0030] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, or two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0031] Example 1: This embodiment provides an overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release, which mainly includes the following steps:

[0032] S1, select the electronic release for testing with the corresponding rated current according to the structure of the initial power supply and distribution branch to be tested in the power system;

[0033] S2, setting the protection parameters of the test electronic release based on the protection parameters of the thermal-magnetic release of the lower-level molded case circuit breaker in the initial power supply and distribution branch to be tested;

[0034] S3, replacing the thermal-magnetic release of the lower-level molded case circuit breaker in the initial power supply and distribution branch to be tested with the test electronic release, and then re-connecting it in series to the power supply and distribution branch to be tested to form a replaced power supply and distribution branch to be tested;

[0035] S4, select a suitable current generator or power supply device to generate the test current;

[0036] S5, carrying out an overload test and a short-circuit test on the replaced power supply and distribution branch to be tested.

[0037] Furthermore, the initial power supply and distribution branch to be tested includes a three-stage frame circuit breaker and a two-stage molded case circuit breaker, and the frame circuit breakers all use electronic releases. The upper molded case circuit breaker in the two-stage molded case circuit breaker uses an electronic release, and the lower molded case circuit breaker uses a thermal magnetic release.

[0038] Furthermore, in the replaced power supply and distribution branch to be tested, the lower-level molded case circuit breaker adopts the test electronic release, and the protection parameters of the test electronic release are set to be consistent with those of the thermal-magnetic release.

[0039] Furthermore, the protection parameters include long-delay protection parameters and instantaneous protection parameters.

[0040] Furthermore, whether the electronic release for testing is actuated is determined by collecting information on whether the electronic release for testing outputs a tripping signal.

[0041] Furthermore, when the electronic release for testing is actuated, its magnetic flux converter is actuated, and the output current during the actuation is read by the electronic release for testing, and a corresponding tripping signal is output.

[0042] Furthermore, the overload action time of the overload test is manually recorded using a stopwatch.

[0043] Furthermore, the test current is generated by a current generator, or by a power supply device of a test platform according to test conditions.

[0044] Example 2. This embodiment provides an overcurrent protection test method based on simulating the protection characteristics of a thermal-magnetic release. This method simulates the long-delay and instantaneous protection characteristics of a thermal-magnetic release by using an electronic release to carry out an overload protection test on the power system, thereby verifying the selectivity and effectiveness of the overcurrent protection design of the power system.

[0045] Furthermore, for typical power supply and distribution branches containing thermal-magnetic circuit breakers, a simulation method is used to replace the overload protection test method of directly connecting a large current to the circuit breaker. The series branch containing the thermal-magnetic circuit breaker is replaced with a series branch of an electronic release, and this method is used to carry out the power system overcurrent protection test.

[0046] Furthermore, by utilizing the feature that the protection characteristics of the electronic trip unit can be edited within a certain range, the long-delay protection parameters and instantaneous protection parameters of the electronic trip unit are set with reference to those of the thermal-magnetic trip unit.

[0047] Furthermore, whether the electronic trip device is actuated is determined by collecting information on whether the electronic trip device outputs a trip signal.

[0048] Furthermore, the test current may be generated by a current generator, or by a power supply device of the test platform according to the test conditions.

[0049] In this embodiment, the typical power supply and distribution branches of the ship power system often include three to four-level frame circuit breakers and three-level and above molded case circuit breakers. Currently, the selectivity between frame circuit breakers and between frame circuit breakers and molded case circuit breakers can be well achieved. Currently, the selectivity between molded case circuit breakers can be achieved at most two levels. Therefore, the typical branches of the power system protection test usually include three-level frame circuit breakers and two-level molded case circuit breakers, such as Figure 1 As shown, the upper molded case circuit breaker typically uses an electronic release, while the lower molded case circuit breaker uses a thermal-magnetic release. Furthermore, the selectivity between 100A and 200A molded case circuit breakers and the upper circuit breaker is a key and challenging aspect of protection verification testing. Therefore, the terminal circuit breakers of a typical test branch are typically selected from these two specifications.

[0050] The power system overcurrent protection test method based on simulating the protection characteristics of the thermal magnetic release of the present invention includes the following steps:

[0051] Step 1: Use a 100A or 200A electronic release to set the protection parameters with reference to the thermal-magnetic release of the same specifications;

[0052] Step 2: Follow Figure 1 The series connection method shown is to connect the electronic trip units in series, such as Figure 2 As shown;

[0053] Step 3: Select a suitable current generator or power supply to generate the test current;

[0054] Step 4: Reference Figure 2 Complete the installation and wiring of the current generator or test power supply and electronic release, and carry out overload test and short-circuit test respectively. When the protection is activated, the flux converter of the electronic release is activated, and the output current during the action is read by the test electronic release. The overload action time is manually recorded using a stopwatch.

[0055] like Figure 2 As shown, the last level electronic release of the test branch can be 100A or 200A. According to the above method, the electronic release of the molded case circuit breaker 100E / 200E series is used to simulate the action characteristics of the 100P / 200P series. Figure 3 、 Figure 4 In the figure, the curve on the left is the simulation curve of the electronic release, and the curve on the right is the curve of the thermal-magnetic release. The electronic release of the same specification can better simulate the thermal-magnetic release in the long delay range. Due to the structural characteristics of the two types of releases, there is a slight difference in their curves in the instantaneous range.

[0056] Figure 5 and Figure 6 The selective protection curve between 100A or 200A molded case circuit breaker and upper circuit breaker is shown. Figure 5 and Figure 6 The leftmost side shows the protection curves of 200A and 100A thermal magnetic molded case circuit breakers. Figure 3 、 Figure 4 The simulation curve of the electronic release shown is slightly different from that of the thermal-magnetic release. However, as the terminal circuit breaker, it can be seen from the simulation curve that it operates faster, which does not affect the effectiveness of the selective protection verification test.

[0057] Furthermore, all parts of this application that are not described in detail are the same as the existing technology or are implemented using the existing technology.

[0058] In summary:

[0059] 1. The present invention uses an electronic release to simulate the overcurrent protection characteristics of a thermal-magnetic release to conduct power system overload and short-circuit protection tests. This can verify the selectivity and effectiveness of the power system overcurrent protection design, making up for the deficiency of the existing thermal-magnetic release in being unable to conduct overcurrent simulation tests, and avoiding arcing, ablation, etc. caused by the circuit breaker being interrupted by large currents.

[0060] 2. The present invention provides an overcurrent protection simulation test method for a power system equipped with a thermal-magnetic release, which can accurately and efficiently verify the correctness of the system protection design.

[0061] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release, characterized in that: The steps include: S1, select the electronic release for testing with the corresponding rated current according to the structure of the initial power supply and distribution branch to be tested in the power system; S2, setting the protection parameters of the test electronic release based on the protection parameters of the thermal-magnetic release of the lower-level molded case circuit breaker in the initial power supply and distribution branch to be tested; S3, replacing the thermal-magnetic release of the lower-level molded case circuit breaker in the initial power supply and distribution branch to be tested with the test electronic release, and then re-connecting it in series to the power supply and distribution branch to be tested to form a replaced power supply and distribution branch to be tested; S4, select a suitable current generator or power supply device to generate the test current; S5, carrying out an overload test and a short-circuit test on the replaced power supply and distribution branch to be tested.

2. The overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release according to claim 1, characterized in that: The initial power supply and distribution branch to be tested includes a three-stage frame circuit breaker and a two-stage molded case circuit breaker. The frame circuit breakers all use electronic releases. The upper molded case circuit breaker in the two-stage molded case circuit breaker uses an electronic release, and the lower molded case circuit breaker uses a thermal magnetic release.

3. The overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release according to claim 2, characterized in that: In the replaced power supply and distribution branch to be tested, the lower-level molded case circuit breaker adopts the test electronic release, and the protection parameters of the test electronic release are set to be consistent with those of the thermal-magnetic release.

4. The overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release according to claim 3, characterized in that: The protection parameters include long-time delay protection parameters and instantaneous protection parameters.

5. The overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release according to claim 1, characterized in that: Whether the electronic release for testing is actuated is determined by collecting information on whether the electronic release for testing outputs a tripping signal.

6. The overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release according to claim 1, characterized in that: When the electronic release for testing is actuated, its magnetic flux converter is actuated, and the output current during the actuation is read by the electronic release for testing, and a corresponding tripping signal is outputted.

7. The overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release according to claim 1, characterized in that: The overload action time of the overload test is manually recorded using a stopwatch.

8. The overcurrent protection test method based on simulating the protection characteristics of a thermal magnetic release according to claim 1, characterized in that: The test current is generated by a current generator, or by a power supply device of a test platform according to test conditions.

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