Introduction
Theoretical Illustration
1. GPS Timing Principle
(2)
2. Interference Principle of Anti-UAV Equipment and the Satellite Quality of TSD
2.1 SAE
2.2 DAE
3. Interference Principle of Anti-UAV Equipment and the Time Accuracy of TSD
4. EMI Evaluation Method with Multiple Indicators to Investigate the Impact of Anti-UAV Equipment on TSD
Simulation Analysis and Result Discussion
1. Mathematical Model
2. Boundary Condition Settings
3. Simulation and Calculation Results
Experimentation
1. Experimental Equipment Parameters
2. Experimental Environment Settings
3. Detection and Analysis of EMI Signals Power Intensity in Anti-UAV Equipment
4. Influence and Analysis of EMI Signals on Satellite Quality
5. Influence and Analysis of EMI Signals on Time Accuracy
Conclusion
1) Since the TSD is a double modular redundancy of the GPS and BDS, it is only when the GPS and BDS antennas are disturbed simultaneously that the TSD attains a punctual state. After the duration of the punctual state exceeds 1 hour, the time accuracy will exceed the threshold of 1 μs, posing a severe threat to automatic devices in substations.
2) An EMI evaluation method involving multiple indicators is proposed to judge whether the TSD is disturbed. When Rjs reaches 10, NG becomes 0 for SAE or becomes equal to the number of false GPS satellites for DAE, or δtu is lower than 1 μs, it is determined that the received GPS signal has been disturbed. Furthermore, when Rjs reaches 30, NB is less than 4 for DAE, or δtu is higher than 1 μs, it is determined that the received GPS and BDS signals have been disturbed.
3) Based on the results obtained from the EMI evaluation method, the simulation, and the experiment, DAE is found to be more suitable for installation in substations. Specifically, the installation distance between the DAE and the TSD directly determines the degree of disturbance. When the DAE is installed more than 60 m away from the TSD, the influence of the EMI on the device is negligible. However, at a distance of 10–60 m, the received GPS signal is influenced by the DAE. In particular, when the DAE is located within 10 m of the TSD, the received GPS and BDS signals both experience disturbances, which are responsible for the TSD being in a punctual state.