Verification Method for Bus Differential Protection and Synchronous Sampling Error in Ship Closed-Loop Power Supply Network

Abstract

This invention discloses a method for verifying bus differential protection and synchronous sampling error in a ship's closed-loop power supply network. The steps include: (1) constructing a semi-physical closed-loop verification platform; (2) verifying synchronous sampling error; (3) verifying closed-loop fault injection and protection action; and (4) generating a verification evaluation report. This invention combines bus differential protection logic with the CloudPSS simulation platform to construct an efficient and flexible closed-loop operation verification method. This significantly improves the adaptability and reliability of bus differential protection in complex operating environments, solves the problem of false or non-operation of bus differential protection due to data synchronization errors in existing technologies, and provides a test verification method that can truly reflect the system's operating status.

Description

Technical Field

[0001] This invention belongs to the technical field of power system closed-loop operation and relay protection testing and verification. Specifically, it relates to a method for verifying the differential protection and synchronization sampling error of the busbar in a ship closed-loop power supply network. It is applicable to the performance evaluation and synchronization verification of differential protection devices in power supply systems of large ships, special ships, and new types of ships. Background Technology

[0002] In shipboard power systems, especially in large and special-purpose vessels employing closed-loop power supply structures, the busbar, as the core node of the power system, is crucial to the safety of the entire power supply system. Busbar differential protection is an important means of ensuring the safe operation of the busbar; its core principle is to determine whether a fault has occurred by comparing the vector sum of the currents in each branch of the busbar. However, due to the complex structure, harsh operating environment, and strong electromagnetic interference inherent in shipboard power supply systems, traditional busbar differential protection faces numerous challenges in practical applications.

[0003] Currently, bus differential protection systems generally rely on the synchronous sampling data of multiple current transformers (CTs) to accurately calculate the bus current. However, due to slight differences in sampling time between CTs, or problems such as communication delays and clock asynchrony, the sampled data can easily become inconsistent in time, introducing data synchronization errors. This error directly affects the accuracy of differential protection judgments, causing maloperation or failure to operate, and in severe cases, may lead to system failures or even power outages.

[0004] Furthermore, existing experimental verification methods for bus differential protection are mostly static tests or simulation verifications based on fixed models, which cannot accurately reflect the actual performance of ship power supply systems under complex operating conditions and dynamic changes. Therefore, the lack of an experimental verification method that can simulate the actual operating environment and evaluate the impact of data synchronization errors on protection performance has become a key issue restricting the performance improvement of ship bus differential protection systems.

[0005] Among existing related patent technologies, patent document (CN121325576A) discloses a differential protection closed-loop simulation method based on a high-performance all-electromagnetic transient simulation platform. This method focuses on assessing the impact of CloudPSS modeling granularity in a purely digital environment on differential protection, and achieves primary and secondary data interaction through FFT and signal merging. However, it relies entirely on a fully digital simulation model and lacks semi-physical closed-loop interaction with actual protection hardware (such as integrated protection devices, merging units, and fiber optic communication links). It cannot realistically reproduce CT sampling clock drift, merging unit networking delay, and hardware interface synchronization errors in actual ship engineering, resulting in deviations between the verification results and actual ship operating conditions, making it difficult to directly guide the synchronization verification of ship differential protection systems.

[0006] For example, patent document (CN116467201A) discloses a closed-loop testing system and method for substation secondary equipment and virtual protection. This method uses a real-time database and time stamps to compare signals between a digital simulation platform and real / virtual protection devices. However, its application scenario focuses on onshore substations, and the protection logic test emphasizes the comparison of the output of virtual algorithms and real devices, without topology adaptation for the unique multi-bus and multi-generator parallel structure of ship closed-loop networks. More importantly, this method does not provide a quantitative evaluation mechanism for the synchronization error of multi-path sampling data, lacks synchronization margin judgment logic based on phase difference-time difference conversion, and cannot solve the problem of verifying the synchronization sampling error of ship differential protection under complex communication links.

[0007] In summary, there is an urgent need for a semi-physical verification method that can integrate high-fidelity digital simulation with actual protection hardware, accurately quantify synchronous sampling errors, and perform closed-loop verification of differential protection selectivity and operating time under dynamic fault conditions. Summary of the Invention

[0008] The purpose of this invention is to provide a test verification method for bus differential protection and data synchronization sampling error applicable to ship closed-loop power supply networks. It aims to solve the problem of bus differential protection maloperation or failure to operate caused by data synchronization error in the prior art, and to provide a test verification method that can truly reflect the system operating status.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A method for verifying the differential protection and synchronous sampling error of a ship's closed-loop power supply network bus includes the following steps: S1. Construct a semi-physical closed-loop verification platform: Build a digital simulation model of the ship's closed-loop power supply network based on the CloudPSS real-time simulation platform, and configure centralized control and protection, interval protection and merging units. The current analog input terminal of the centralized control and protection is configured with a dual-path receiving architecture, including a direct input path and an indirect input path transmitted through the optical fiber of the interval protection and merging unit. S2. Synchronous sampling error verification: Inject a synchronous test signal into the dual path, and collect the current waveforms of the direct path and the indirect path respectively by forced waveform recording. Calculate the maximum phase difference Δφ between the two path currents, and calculate the time difference Δt according to the formula Δt=(Δφ / 360)×20 to determine whether the synchronization requirements are met. S3. Closed-loop fault injection and protection action verification: Set up bus zone fault and external fault conditions in the CloudPSS model, record the trip signal output by the centralized control and integrated protection, the corresponding switch status and event log, and verify the selectivity and action time of the differential protection. S4. Generate verification and evaluation report: Combine the synchronization error data from step S2 with the action timing and selectivity results from step S3 to output the adaptive evaluation conclusion of the bus differential protection system.

[0011] Furthermore, the specific configuration of the dual-path receiving architecture described in step S1 is as follows: the test module includes a CloudPSS primary system, a centralized control protection system, three bay protection systems, and a merging unit. The analog current is sent to the centralized control protection system through two paths: one is direct input; the other is that it is first collected by the bay protection system and then transmitted to the centralized control protection system through the merging unit via optical fiber.

[0012] Furthermore, the topology of the digital simulation model of the ship's closed-loop power supply network in step S1 includes: multiple generator sets, bus tie switches B1 and B2, load branches, and circuit breakers CB1~CB12 distributed in each branch. The positive direction of the current transformer CT at each switch is set so that the current flows out of the bus B11.

[0013] Furthermore, the specific judgment logic for the synchronous sampling error verification in step S2 is as follows: taking the 50Hz power system reference period of 20ms as the conversion benchmark, when the calculated time difference Δt < 1ms, it is determined that the dual-path current synchronization meets the differential protection calculation requirements; when Δt ≥ 1ms, it is determined that there is a risk of synchronous sampling error, and the clock synchronization parameters of the merging unit or the communication link configuration need to be adjusted.

[0014] Furthermore, in step S3, during the synchronous sampling error verification, to ensure the accuracy of the bus differential protection calculation, a synchronous test structure consisting of a bay integrated protection unit, a centralized control integrated protection unit, and a merging unit is used. Before the test, the synchronicity of the current transmitted through the two paths needs to be verified.

[0015] Furthermore, the specific operation of the fault verification in the bus area in step S3 is as follows: set a three-phase short-circuit fault F1 in the bus B11 area, monitor the response time of the trip signal issued by the centralized control and protection to the signal received by CloudPSS, and verify the trip action sequence and logic consistency of switches CB1, CB5, CB11 and bus tie B1.

[0016] Furthermore, the specific operation of the external fault verification in step S3 is as follows: set a three-phase short-circuit fault F2 outside the bus B11 area, verify whether the integrated control and protection system issues a trip signal, and confirm that switches CB1, CB5, bus tie B1 and CB11 are all in the closed state and that there is no fault event log recorded in the integrated control system.

[0017] Furthermore, the method is specifically designed for the verification of bus differential protection systems in ship closed-loop power supply networks. It can simulate the operating state of real power systems in a high-fidelity simulation environment, realize real-time interaction and closed-loop verification between protection logic and simulation model, and thus effectively evaluate the action behavior and performance of the protection system under different operating conditions.

[0018] Compared with the prior art, the present invention has the following significant advantages: 1. Pioneering semi-physical dual-path synchronous verification architecture: Breaking through the limitations of pure digital simulation, it uses parallel input via direct connection and fiber optic indirect paths to realistically reproduce the actual sampling link of the ship's integrated support system, accurately locate and quantify synchronous sampling errors.

[0019] 2. Provides an engineering-operable synchronization error determination model: Based on the physical conversion relationship Δt=(Δφ / 360)×20, the abstract phase difference is transformed into a time difference threshold (<1ms) that the protection device can execute, filling the gap in the quantitative evaluation of synchronization margin of ship differential protection.

[0020] 3. Achieve dynamic fault closed-loop performance verification: Inject intra-zone / extra-zone faults into the CloudPSS high-fidelity ship topology, and combine them with the actual integrated protection hardware response to simultaneously verify the protection action time (≤2.5ms), selectivity and switch tripping logic, which greatly improves the real ship mapping of the verification results.

[0021] 4. Enhance the safety and reliability of ship power supply systems: Through dynamic synchronization error injection and multi-dimensional evaluation report generation, protection boundary defects under extreme operating conditions are exposed in advance, providing a scientific basis for optimizing ship differential protection setting parameters, merging unit clock configuration, and communication network transformation.

[0022] 5. Promote the application of domestically produced simulation software in the field of ship protection: Make full use of the high-precision modeling and real-time interaction capabilities of the CloudPSS platform to build an independent and controllable semi-physical verification system for ship relay protection, and reduce dependence on imported testing equipment.

[0023] In summary, this invention proposes a test verification method for bus differential protection and data synchronization sampling error applicable to ship closed-loop power supply networks. By combining the bus differential protection logic with the CloudPSS simulation platform, an efficient and flexible closed-loop operation verification method is constructed, significantly improving the adaptability and reliability of bus differential protection in complex operating environments. This method can simulate the operating state of a real power system in a high-fidelity simulation environment, realizing real-time interaction and closed-loop verification between the protection logic and the simulation model, thereby effectively evaluating the action behavior and performance of the protection device under different operating conditions. Simultaneously, this invention fully utilizes the high-precision modeling and real-time simulation capabilities of the domestically developed CloudPSS platform, promoting the application of domestic simulation software in the field of relay protection verification and enhancing my country's independent controllability in power system simulation and protection technologies. In conclusion, this invention not only improves the verification efficiency and accuracy of directional blocking protection but also provides strong technical support for the safe operation of smart grids and new power systems. Attached Figure Description

[0024] Figure 1 This is a test topology diagram of the bus differential protection of the present invention; Figure 2 This is a schematic diagram of the hardware-in-the-loop simulation module of the present invention; Figure 3 This is a physical layout diagram of the hardware-in-the-loop simulation verification platform of the present invention; Figure 4 This is a structural diagram of the bus differential protection system of the present invention; Figure 5 This is a schematic diagram of the synchronous test structure of the present invention; Figure 6 This is a schematic diagram of the current wiring of the present invention; Figure 7 This is a schematic diagram of the experimental simulation of the present invention (fault in area F1); Figure 8 This is a schematic diagram of the fault recording of the present invention (comparison of channels J1 and J5). Figure 9 This is a schematic diagram of the phase difference between the two-path currents in this invention; Figure 10 This is a simulation diagram of the bus differential protection of the present invention (including CT / PT configuration); Figure 11 This is a timing diagram showing the operation of the three-phase short-circuit protection at point F1 in this invention; Figure 12 This is a diagram showing the operation of the three-phase short-circuit switch at point F1 in this invention; Figures 13(a) and 13(b) are log records of the F1 three-phase short-circuit integrated protection system of the present invention; Figure 14 This is a state diagram of the three-phase short-circuit switch outside the F2 zone of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] The present invention provides a method for verifying the differential protection and synchronous sampling error of a bus in a closed-loop power supply network of a ship, comprising the following steps: (1) constructing a semi-physical closed-loop verification platform, (2) verifying the synchronous sampling error, (3) verifying the closed-loop fault injection and protection action, and (4) generating a verification evaluation report.

[0027] Example 1: For the following topology, B11 is the protected bus, and the positive direction of the CT at each switch is the outflow of current from bus B11.

[0028] Hardware-in-the-loop simulation platform such as Figure 2As shown in Figure 3, the test module includes a CloudPSS primary system, one centralized control integrated protection unit, three bay integrated protection units, and one merging unit. Analog current is fed into the centralized control integrated protection unit via two paths: one is direct input; the other is first acquired by the bay integrated protection unit, then transmitted to the centralized control integrated protection unit via optical fiber through the merging unit. The system structure is as follows: Figure 4 As shown.

[0029] To ensure the accuracy of the bus differential protection calculations, the synchronization of the current transmitted through the two paths mentioned above must be verified before the test. For example... Figure 5 As shown, the following system is constructed using one bay integrated protection unit, a centralized control integrated protection unit, and a merging unit.

[0030] Example 2: For the bus differential protection scheme, the main contents that need to be verified include: 1) Data sampling synchronization test verification 2) Protection selectivity: Verify that the differential protection operates accurately when there is a fault within the bus zone, but does not operate when there is a fault outside the zone.

[0031] 3) Protective action time.

[0032] Input the current output from switch CB1 of CloudPSS into the jumper protection and the central control protection respectively, and connect the terminals as follows: Figure 6 As shown.

[0033] A fault occurred at busbar B11; the simulation diagram is as follows. Figure 7 As shown. During the test, a three-phase short-circuit fault was simulated, and forced waveform recording was used to record the two-path short-circuit current waveforms. The waveform recording is as follows. Figure 8 As shown, Figure 8 Channel J1 is the current waveform directly input to the centralized control and protection system via CloudPSS, while channel J5 is the current waveform input to the centralized control and protection system via the merging unit.

[0034] By analyzing the phase difference between the two path currents, the maximum phase difference between the two path currents after the short circuit is 1.4°. Figure 9 Take phase A as an example.

[0035] Based on the fundamental characteristics of a 50Hz power system, a complete cycle (360°) corresponds to a duration of 20ms. Phase difference With time difference The relationship can be expressed as follows:

[0036] That is when When the angle is 1.4°, the time difference can be obtained as follows:

[0037] The time difference between the two current paths is less than 1ms, which meets the current synchronization requirements.

[0038] Experimental simulation diagram as follows Figure 10 As shown. Figure 10 Current transformers (CTs) are installed at the red switches CB1, CB5, CB11 and bus tie B1, and a voltage transformer (PT) is installed at bus tie B1. The secondary current of the CTs at each switch and the secondary voltage measured by the PT at bus tie B1 are output through the analog output channel.

[0039] A fault is set at F1 in busbar B11 zone, with the fault type being a three-phase short circuit. The protection operation time is as follows: Figure 11 As shown, the time from the occurrence of the fault to CloudPSS receiving the protection action signal issued by the integrated protection system is 2.5ms. The test results meet the main protection action time requirements.

[0040] like Figure 12 As shown, switches CB1, CB5, bus tie B1, and CB11 operated, and the test results met the main protection selectivity requirements.

[0041] The integrated protection event log is shown in Figure 13(a) and Figure 13(b). Figure 13(a) and Figure 13(b) show that the bus differential protection operated during the fault.

[0042] An external three-phase short circuit is set at F2, such as... Figure 14 As shown, at this time, the integrated protection system does not issue a trip signal, the protection does not operate, and switches CB1, CB5, bus tie B1, and CB11 do not trip. The integrated protection system has no event record, thus meeting the selectivity requirements.

[0043] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the concept and scope of the present invention. Therefore, all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for shipboard closed loop power supply network bus differential protection and synchronized sampling error verification, characterized in that, Includes the following steps: S1. Construct a semi-physical closed-loop verification platform: Build a digital simulation model of the ship's closed-loop power supply network based on the CloudPSS real-time simulation platform, and configure centralized control and protection, interval protection and merging units. The current analog input terminal of the centralized control and protection is configured with a dual-path receiving architecture, including a direct input path and an indirect input path transmitted through the optical fiber of the interval protection and merging unit. S2. Synchronous sampling error verification: Inject a synchronous test signal into the dual path, and collect the current waveforms of the direct path and the indirect path respectively by forced waveform recording. Calculate the maximum phase difference Δφ between the two path currents, and calculate the time difference Δt according to the formula Δt=(Δφ / 360)×20 to determine whether the synchronization requirements are met. S3. Closed-loop fault injection and protection action verification: Set up bus zone fault and external fault conditions in the CloudPSS model, record the trip signal output by the centralized control and integrated protection, the corresponding switch status and event log, and verify the selectivity and action time of the differential protection. S4. Generate verification and evaluation report: Combine the synchronization error data from step S2 with the action timing and selectivity results from step S3 to output the adaptive evaluation conclusion of the bus differential protection system.

2. The method of bus differential protection and synchronized sampling error validation for a shipboard closed loop power distribution network of claim 1, wherein, The specific configuration of the dual-path receiving architecture described in step S1 is as follows: The test module includes a CloudPSS primary system, a centralized control protection system, three bay protection systems, and a merging unit. The analog current is sent to the centralized control protection system through two paths: one is direct input; the other is that it is first collected by the bay protection system and then transmitted to the centralized control protection system through the merging unit via optical fiber.

3. The method for verifying the differential protection and synchronous sampling error of the busbar in a ship's closed-loop power supply network according to claim 1, characterized in that, The topology of the digital simulation model of the ship's closed-loop power supply network in step S1 includes: multiple generator sets, bus tie switches B1 and B2, load branches, and circuit breakers CB1~CB12 distributed in each branch. The positive direction of the current transformer CT at each switch is set so that the current flows out of the bus B11.

4. The method for verifying the differential protection and synchronous sampling error of the busbar in a ship's closed-loop power supply network according to claim 1, characterized in that, The specific judgment logic for the synchronous sampling error verification in step S2 is as follows: taking the 50Hz power system reference period of 20ms as the conversion benchmark, when the calculated time difference Δt < 1ms, it is determined that the dual-path current synchronization meets the differential protection calculation requirements; when Δt ≥ 1ms, it is determined that there is a risk of synchronous sampling error, and the clock synchronization parameters of the merging unit or the communication link configuration need to be adjusted.

5. The method for verifying the differential protection and synchronous sampling error of the busbar in a ship's closed-loop power supply network according to claim 1, characterized in that, In step S3, during the synchronous sampling error verification, to ensure the accuracy of the bus differential protection calculation, a synchronous test structure consisting of a bay integrated protection unit, a centralized control integrated protection unit, and a merging unit is used. Before the test, the synchronicity of the current transmitted through the two paths needs to be verified.

6. The method for verifying the differential protection and synchronous sampling error of the busbar in a ship's closed-loop power supply network according to claim 1, characterized in that, The specific operation of the fault verification in the bus area in step S3 is as follows: set a three-phase short circuit fault F1 in the bus B11 area, monitor the response time of the trip signal issued by the centralized control and protection to the signal received by CloudPSS, and verify the trip action sequence and logic consistency of switches CB1, CB5, CB11 and bus tie B1.

7. The method for verifying the differential protection and synchronous sampling error of the busbar in a ship's closed-loop power supply network according to claim 1, characterized in that, The specific operation of the external fault verification in step S3 is as follows: set a three-phase short circuit fault F2 outside the bus B11 area, verify whether the integrated control and protection system issues a trip signal, and confirm that switches CB1, CB5, bus tie B1 and CB11 are all in the closed state and that there is no fault event log recorded in the integrated control system.

8. The method for verifying the differential protection and synchronous sampling error of the busbar in a ship's closed-loop power supply network according to any one of claims 1-7, characterized in that, The method is specifically designed for the verification of bus differential protection systems in ship closed-loop power supply networks. It can simulate the operating state of real power systems in a high-fidelity simulation environment, realize real-time interaction and closed-loop verification between protection logic and simulation model, and thus effectively evaluate the action behavior and performance of protection systems under different operating conditions.

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