Design Of Power System Sensor Network Nodes

In recent years, the electric power industry is growing rapidly and the topology is becoming more and more complex. The transmission network is inter-connected and extra-high voltage with AC/DC mixed transmission network bulk power system has been broadly built. More and more non-linear power equipments are installed, introducing large amount of harmonic into the electric power network. On the other hand, the market-oriented electric power system tends to operate on safety margin to pursuit higher profit. These characteristics challenge the security of the modern electric power system. The bus voltage phasor is one of the main parameters that reflect the stability of the electric power system. The voltage phasor that is measured real-time provides important information for safe dispatch and stabile control. Therefore, it is important to build a real-time wide-area synchro phasor measurement network for monitoring and control of the electric power system's stability.This project aims at designing an experiment platform for electric power system dynamic monitoring network. Based on the state-of-art analysis in this field, the author of this thesis proposed a power system monitoring network base on IEEE 1451.2 standard, the power system sensor network (PSSN). The system adopts the synchro phasor measurement technique, measuring the voltage phasor in a real-time manner.Ethernet technology is used in PSSN, in order to satisfy the requirement of real-time and large-scale data transmission in power system dynamic monitoring. Ethernet is the prototype of next generation field bus network, and it represents the development trend of field bus. In order to achieve high-speed and reliable communication, the author of the thesis designed the network capable application processor (NCAP) based on the ARM microprocessor. The NCAP has 100M Fast Ethernet Interface and can provide high-speed data transmission channel.There are two major difficulties in synchro-phasor measurement: the algorithm of synchronous phasor and high-precision time synchronization. Based on the analysis of the common phasor measurement method, an improved DFT algorithm is used to improve the accuracy of phase measurement under frequency fluctuation. To overcome the disadvantage in GPS timing, the author designed a time synchronization scheme base on GPS timing and IEEE 1588 standard. This design not only guarantees to satisfy the requirement of the wide area time synchronization, but also provides high enough clock accuracy even when GPS is unavailable.