In electrical networks, there are often emergencies that lead to power outages. In order to avoid them, it is necessary to create systems that monitor the state of the electrical network and the processes taking place in it. One such system is a system for synchronous measurement of network parameters at two different points at the same time (PMU system). The points at which the measurement is made are often significantly removed from each other (for tens to hundreds of kilometers). Synchronize measurements using a cable line in this situation is impossible. Because of this, you need to use the GPS time signals to synchronize. To develop PMU-systems, it is necessary to test the operation of such a system. It is necessary to test the work in conditions of a low level of the received GPS-signal, its interference or a high level of interference.
The problem or task
For research purposes, it was necessary to develop a system capable of generating GPS signals. The purpose of the development is to simulate the interference of GPS signals and to study the influence of the quality and level of the satellite signals received by the distributed system on the accuracy of the measurement synchronization
To solve the problem, a GPS signal generator was developed. The generator made it possible to simulate various conditions for receiving a GPS signal by a synchronous measurement system. The GPS signal generator is built on the PXI platform. The generator is controlled by an NI PXIe 8115 controller in an NI PXIe 1062Q chassis. The main element of the system was the NI PXIe-250 vector RF signal generator in the range of 2,7 kHz-5672 GHz. The RF generator consists of an NI PXIe 5442 arbitrary waveform generator and an NI PXI 5610 RF upconverter. The software is written in the NI LabVIEW programming environment. The GPS RF signal conditioning module is developed using the NI GNSS Simulation toolkit. The developed system made it possible to study the influence of the quality of the GPS signal on the accuracy of measurement synchronization. This made it possible to develop a system of synchronous measurements with a desynchronization value not exceeding 1 μs.