| Phasor Measurement Unit (PMU) has become the basic tool of dynamic monitoring in power system. Highly precise, reliable and secure time synchronization is of great importance to PMU measurement as the essential feature of which is synchronized measurement. At present, the time synchronization information source of PMU is changing gradually with the operation of BeiDou II Navigation Satellite and development of smart substations. The changing is from time synchronization between substations based on GPS to BeiDou II combined with network time synchronization in substations. Therefore, study on time synchronization method, synchronization deviation and its impacts on PMU measurement is of great importance. It is of vital significance for the realization of dynamic security monitoring in large power grid effectively and the safe operation of the power system.Characteristics of time synchronization between substations based on the test platform of BeiDou II time synchronization characteristics are analyzed emphatically through three aspects of accuracy, reliability and safety. The reason of time synchronization deviation and jitter is mainly discussed and suggestions for improving products are given, meanwhile the impact of synchronization characteristic on PMU measurement is analyzed.The factors which affect the precision of time synchronization of PTP in substations are discussed based on the principle of PTP (Precision Time Protocol). The simulation test platform of time synchronization in smart substations was built to study on PTP characteristics. It reflects that precision of PTP has differences under different delay mechanisms, different clock modes and switches are put into the network as well as abnormal synchronization under the impact of network storm with GOOSE (Generic Object Oriented Substation Event) messages and SV (Sampled Value) messages. Meanwhile the impact of synchronization characteristic on PMU measurement is analyzed.The impact of time synchronization deviation caused by synchronization method between and in substations on PMU measurement is analyzed. In this thesis, two kinds of PMUs installed in substations and power plants are discussed respectively. The phasor calculation formulas of PMUs in substations with time synchronization deviation in power system dynamic state are derived emphatically. The impact of time synchronization deviation on phasor measurement is analyzed. In addition, the relation between the generator rotor angle measured by PMUs in power plants and the time synchronization deviation is analyzed through the generator rotor angle measurement principle. Finally, the physically experimental platform is built and the validity of the theoretical analysis is verified by conducting the steady state and the dynamic state experiments. |
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